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Sample records for k-ras increases radiosensitivity

  1. Lin28-let7 Modulates Radiosensitivity of Human Cancer Cells With Activation of K-Ras

    SciTech Connect

    Oh, Jee-Sun.; Kim, Jae-Jin; Byun, Ju-Yeon; Kim, In-Ah

    2010-01-15

    Purpose: To evaluate the potential of targeting Lin28-let7 microRNA regulatory network for overcoming the radioresistance of cancer cells having activated K-Ras signaling. Methods and Materials: A549 lung carcinoma cells and ASPC1 pancreatic cancer cells possessing K-RAS mutation were transfected with pre-let7a microRNA or Lin28 siRNA, respectively. Clonogenic assay, quantitative reverse transcription polymerase chain reaction, and Western analysis were performed. The effects of Lin28 on SQ20B cells having wild-type K-RAS, and a normal fibroblast were also assessed. Results: The overexpression of let-7a decreased expression of K-Ras and radiosensitized A549 cells. Inhibition of Lin28, a repressor of let-7, attenuated K-Ras expression and radiosensitized A549 and ASPC1 cells. Neither SQ20B cells expressing wild-type K-RAS nor HDF, the normal human fibroblasts, were radiosensitized by this approach. Conclusions: The Lin28-let7 regulatory network may be a potentially useful therapeutic target for overcoming the radioresistance of human cancers having activated K-Ras signaling.

  2. Comparative analysis of radiosensitizers for K-RAS mutant rectal cancers.

    PubMed

    Kleiman, Laura B; Krebs, Angela M; Kim, Stephen Y; Hong, Theodore S; Haigis, Kevin M

    2013-01-01

    Approximately 40% of rectal cancers harbor activating K-RAS mutations, and these mutations are associated with poor clinical response to chemoradiotherapy. We aimed to identify small molecule inhibitors (SMIs) that synergize with ionizing radiation (IR) ("radiosensitizers") that could be incorporated into current treatment strategies for locally advanced rectal cancers (LARCs) expressing mutant K-RAS. We first optimized a high-throughput assay for measuring individual and combined effects of SMIs and IR that produces similar results to the gold standard colony formation assay. Using this screening platform and K-RAS mutant rectal cancer cell lines, we tested SMIs targeting diverse signaling pathways for radiosensitizing activity and then evaluated our top hits in follow-up experiments. The two most potent radiosensitizers were the Chk1/2 inhibitor AZD7762 and the PI3K/mTOR inhibitor BEZ235. The chemotherapeutic agent 5-fluorouracil (5-FU), which is used to treat LARC, synergized with AZD7762 and enhanced radiosensitization by AZD7762. This study is the first to compare different SMIs in combination with IR for the treatment of K-RAS mutant rectal cancer, and our findings suggest that Chk1/2 inhibitors should be evaluated in new clinical trials for LARC. PMID:24349411

  3. Absence of K-Ras Reduces Proliferation and Migration But Increases Extracellular Matrix Synthesis in Fibroblasts.

    PubMed

    Muñoz-Félix, José M; Fuentes-Calvo, Isabel; Cuesta, Cristina; Eleno, Nélida; Crespo, Piero; López-Novoa, José M; Martínez-Salgado, Carlos

    2016-10-01

    The involvement of Ras-GTPases in the development of renal fibrosis has been addressed in the last decade. We have previously shown that H- and N-Ras isoforms participate in the regulation of fibrosis. Herein, we assessed the role of K-Ras in cellular processes involved in the development of fibrosis: proliferation, migration, and extracellular matrix (ECM) proteins synthesis. K-Ras knockout (KO) mouse embryonic fibroblasts (K-ras(-/-) ) stimulated with transforming growth factor-β1 (TGF-β1) exhibited reduced proliferation and impaired mobility than wild-type fibroblasts. Moreover, an increase on ECM production was observed in K-Ras KO fibroblasts in basal conditions. The absence of K-Ras was accompanied by reduced Ras activation and ERK phosphorylation, and increased AKT phosphorylation, but no differences were observed in TGF-β1-induced Smad signaling. The MEK inhibitor U0126 decreased cell proliferation independently of the presence of K-ras but reduced migration and ECM proteins expression only in wild-type fibroblasts, while the PI3K-AKT inhibitor LY294002 decreased cell proliferation, migration, and ECM synthesis in both types of fibroblasts. Thus, our data unveil that K-Ras and its downstream effector pathways distinctively regulate key biological processes in the development of fibrosis. Moreover, we show that K-Ras may be a crucial mediator in TGF-β1-mediated effects in this cell type. J. Cell. Physiol. 231: 2224-2235, 2016. © 2016 Wiley Periodicals, Inc. PMID:26873620

  4. K-Ras mutant fraction in A/J mouse lung increases as a function of benzo[a]pyrene dose

    EPA Science Inventory

    K-Ras mutant fraction (MF) was measured to examine the default assumption of low dose linearity in the benzo[a]pyrene (B[a]P) mutational response. Groups of ten male A/J mice (7-9 weeks-old) received a single i.p. injection of 0, 0.05, 0.5, 5, or 50 mg/kg B[a]P, and were sacrifi...

  5. The Differential Effects of Wild-Type and Mutated K-Ras on MST2 Signaling Are Determined by K-Ras Activation Kinetics

    PubMed Central

    Romano, David; Maccario, Helene; Doherty, Carolanne; Quinn, Niall P.

    2013-01-01

    K-Ras is frequently mutated in human cancers. Mutant (mt) K-Ras can stimulate both oncogenic transformation and apoptosis through activation of extracellular signal-regulated kinase (ERK) and AKT pathways and the MST2 pathway, respectively. The biological outcome is determined by the balance and cross talk between these pathways. In colorectal cancer (CRC), a K-Ras mutation is negatively correlated with MST2 expression, as mt K-Ras can induce apoptosis by activating the MST2 pathway. However, wild-type (wt) K-Ras can prevent the activation of the MST2 pathway upon growth factor stimulation and enable transformation by mt K-Ras in CRC cells that express MST2. Here we have investigated the mechanism by which wt and mt K-Ras differentially regulate the MST2 pathway and MST2-dependent apoptosis. The ability of K-Ras to activate MST2 and MST2-dependent apoptosis is determined by the differential activation kinetics of mt K-Ras and wt K-Ras. Chronic activation of K-Ras by mutation or overexpression of Ras exchange factors results in the activation of MST2 and LATS1, increased MST2-LATS1 complex formation, and apoptosis. In contrast, transient K-Ras activation upon epidermal growth factor (EGF) stimulation prevents the formation of the MST2-LATS1 complex in an AKT-dependent manner. Our data suggest that the close relationship between Ras prosurvival and proapoptotic signaling is coordinated via the differential regulation of the MST2-LATS1 interaction by transient and chronic stimuli. PMID:23459937

  6. Mutant K-RAS Promotes Invasion and Metastasis in Pancreatic Cancer Through GTPase Signaling Pathways

    PubMed Central

    Padavano, Julianna; Henkhaus, Rebecca S; Chen, Hwudaurw; Skovan, Bethany A; Cui, Haiyan; Ignatenko, Natalia A

    2015-01-01

    Pancreatic ductal adenocarcinoma is one of the most aggressive malignancies, characterized by the local invasion into surrounding tissues and early metastasis to distant organs. Oncogenic mutations of the K-RAS gene occur in more than 90% of human pancreatic cancers. The goal of this study was to investigate the functional significance and downstream effectors of mutant K-RAS oncogene in the pancreatic cancer invasion and metastasis. We applied the homologous recombination technique to stably disrupt K-RAS oncogene in the human pancreatic cell line MiaPaCa-2, which carries the mutant K-RASG12C oncogene in both alleles. Using in vitro assays, we found that clones with disrupted mutant K-RAS gene exhibited low RAS activity, reduced growth rates, increased sensitivity to the apoptosis inducing agents, and suppressed motility and invasiveness. In vivo assays showed that clones with decreased RAS activity had reduced tumor formation ability in mouse xenograft model and increased survival rates in the mouse orthotopic pancreatic cancer model. We further examined molecular pathways downstream of mutant K-RAS and identified RhoA GTP activating protein 5, caveolin-1, and RAS-like small GTPase A (RalA) as key effector molecules, which control mutant K-RAS-dependent migration and invasion in MiaPaCa-2 cells. Our study provides rational for targeting RhoA and RalA GTPase signaling pathways for inhibition of pancreatic cancer metastasis. PMID:26512205

  7. Oncogenic K-ras confers SAHA resistance by up-regulating HDAC6 and c-myc expression

    PubMed Central

    Zhang, Yi; Tan, Zhiping; Su, Bing; Li, Yu

    2016-01-01

    Histone deacetylase inhibitors (HDIs) represent a new class of anticancer drugs. Suberoylanilide hydroxamic acid (SAHA), the first HDI approved for the treatment of cutaneous T cell lymphoma (CTCL), is currently being tested in clinical trials for other cancers. However, SAHA has been ineffective against solid tumors in many clinical trials. A better understanding of molecular mechanisms of SAHA resistance may provide the basis for improved patient selection and the enhancement of clinical efficacy. Here we demonstrate that oncogenic K-ras contributes to SAHA resistance by upregulating HDAC6 and c-myc expression. We find that the high levels of HDAC6 expression are associated with activated K-ras mutant in colon cancer patients. And expressions of HDAC6 and c-myc are increased in fibroblasts transformed with activated K-ras. Surprisingly, we find that activated K-ras transformed cells are more resistant to SAHA inhibition on cell growth and anchorage-independent colony formation. We show that a K-ras inhibitor sensitizes K-ras mutated lung cancer cells to SAHA induced growth inhibition. We also find that mutant K-ras induces HDAC6 expression by a MAP kinase dependent pathway. Our study suggests that combined treatment with SAHA and K-ras inhibitors may represent an effective strategy to overcome SAHA resistance. PMID:26848526

  8. Oncogenic K-ras confers SAHA resistance by up-regulating HDAC6 and c-myc expression.

    PubMed

    Wang, Qun; Tan, Rong; Zhu, Xin; Zhang, Yi; Tan, Zhiping; Su, Bing; Li, Yu

    2016-03-01

    Histone deacetylase inhibitors (HDIs) represent a new class of anticancer drugs. Suberoylanilide hydroxamic acid (SAHA), the first HDI approved for the treatment of cutaneous T cell lymphoma (CTCL), is currently being tested in clinical trials for other cancers. However, SAHA has been ineffective against solid tumors in many clinical trials. A better understanding of molecular mechanisms of SAHA resistance may provide the basis for improved patient selection and the enhancement of clinical efficacy. Here we demonstrate that oncogenic K-ras contributes to SAHA resistance by upregulating HDAC6 and c-myc expression. We find that the high levels of HDAC6 expression are associated with activated K-ras mutant in colon cancer patients. And expressions of HDAC6 and c-myc are increased in fibroblasts transformed with activated K-ras. Surprisingly, we find that activated K-ras transformed cells are more resistant to SAHA inhibition on cell growth and anchorage-independent colony formation. We show that a K-ras inhibitor sensitizes K-ras mutated lung cancer cells to SAHA induced growth inhibition. We also find that mutant K-ras induces HDAC6 expression by a MAP kinase dependent pathway. Our study suggests that combined treatment with SAHA and K-ras inhibitors may represent an effective strategy to overcome SAHA resistance. PMID:26848526

  9. Profiling of transcripts and proteins modulated by K-ras oncogene in the lung tissues of K-ras transgenic mice by omics approaches.

    PubMed

    Lee, Sojung; Kang, Jungwoo; Cho, Minchul; Seo, Eunhee; Choi, Heesook; Kim, Eunjin; Kim, Junghee; Kim, Heejong; Kang, Gum Yong; Kim, Kwang Pyo; Park, Young-Ho; Yu, Dae-Yeul; Yum, Young Na; Park, Sue-Nie; Yoon, Do-Young

    2009-01-01

    The mutated K-ras gene is involved in approximately 30% of human cancers. In order to search for K-ras oncogene-induced modulators in lung tissues of K-ras transgenic mice, we performed microarray and proteomics (LC/ESI-MS/MS) analysis. Genes (RAB27b RAS family, IL-1RA, IL-33, chemokine ligand 6, epiregulin, EGF-like domain and cathepsin) related to cancer development (Wnt signaling pathway) and inflammation (chemokine/cytokine signaling pathway, Toll receptor signaling) were up-regulated while genes (troponin, tropomodulin 2, endothelial lipase, FGFR4, integrin alpha8 and adenylate cyclase 8) related to the tumor suppression such as p53 pathway, TGF-beta signaling pathway and cadherin signaling pathway were down-regulated by K-ras oncogene. Proteomics approach revealed that up-regulated proteins in lung adenomas of K-ras mice were classified as follows: proteins related to the metabolism/catabolism (increased from 7 to 22% by K-ras gene), proteins related to translation/transcription and nucleotide (from 4 to 6%), proteins related to signal transduction (from 3 to 5%), proteins related to phosphorylation (from 1 to 2%). ATP synthase, Ras oncogene family, cytochrome c oxidase, flavoprotein, TEF 1, adipoprotein A-1 BP, glutathione oxidase, fatty acid BP 4, diaphorase 1, MAPK4 and transgelin were up-regulated by K-ras oncogene. However, integrin alpha1, Ras-interacting protein (Rain), endothelin-converting enzyme-1d and splicing factor 3b were down-regulated. These studies suggest that genes related to cancer development and inflammation were up-regulated while genes related to the tumor suppression were down-regulated by K-ras, resulting in the tumor growth. Putative biomarkers such as cell cycle related genes (Cdc37), cancer cell adhesion (Glycam 1, integrin alpha8, integrin alphaX and Clec4n), signal transduction (Tlr2, IL-33, and Ccbp2), migration (Ccr1, Ccl6, and diaphorase 1 (Cyb5r3) and cancer development (epiregulin) can be useful for diagnosis and as

  10. ERK2-dependent reactivation of Akt mediates the limited response of tumor cells with constitutive K-RAS activity to PI3K inhibition

    PubMed Central

    Toulany, Mahmoud; Minjgee, Minjmaa; Saki, Mohammad; Holler, Marina; Meier, Friedegund; Eicheler, Wolfgang; Rodemann, H Peter

    2014-01-01

    K-RAS mutated (K-RASmut) non-small cell lung cancer (NSCLC) cells are resistant to EGFR targeting strategies. We investigated the impact of K-RAS activity irrespective of mutational status in the EGFR-independent increase in clonogenic cell survival. An analysis of the K-RAS activity status revealed a constitutively high K-RAS activity in K-RASmut NSCLC cells and also in head and neck squamous cell carcinoma (HNSCC) cells overexpressing wild-type K-RAS (K-RASwt). Similar to K-RAS-mutated cells, increased K-RAS activity in HNSCC cells overexpressing K-RASwt was associated with the stimulated production of the EGFR ligand amphiregulin and resistance to EGFR tyrosine kinase (EGFR-TK) inhibitors such as erlotinib. Expression of mutated K-RAS stimulated Akt phosphorylation and increased plating efficiency. Conversely, knockdown of K-RAS in K-RASmut NSCLC cells and in HNSCC cells presenting overexpression of K-RASwt resulted in sensitization to the anti-clonogenic activity of erlotinib. K-RAS activity results in EGFR-dependent and EGFR-independent Akt activity. The short-term treatment (2 h) of cells with EGFR-TK or PI3K inhibitors (erlotinib and PI-103) resulted in the repression of Akt activation, whereas long-term treatment (24 h) with inhibitors led to the reactivation of Akt and improved clonogenicity. The Akt re-activation was MAPK-ERK2-dependent and associated with a lack of complete response to anti-clonogenic activity of PI-103. A complete response was observed when PI-103 was combined with MEK inhibitor PD98059. Together, clonogenicity inhibition in tumor cells presenting constitutive K-RAS activity independent of K-RAS mutational status can be achieved by targeting of EGFR downstream pathways, i.e., PI3K alone or the combination of PI3K and MAPK inhibitors. PMID:24351425

  11. Radiosensitization Effect of STI-571 on Pancreatic Cancer Cells In Vitro

    SciTech Connect

    Chung, Hye Won; Wen, Jing; Lim, Jong-Baeck; Bang, Seung Min; Park, Seung Woo; Song, Si Young

    2009-11-01

    Purpose: To examine STI-571-induced radiosensitivity in human pancreatic cancer cells in vitro. Methods and Materials: Three human pancreatic cancer cell lines (Bxpc-3, Capan-1, and MiaPaCa-2) exhibiting different expression levels of c-Kit and platelet-derived growth factor receptor beta (PDGFRbeta) and showing different K-ras mutation types were used. For evaluation of the antitumor activity of STI-571 in combination with radiation, clonogenic survival assays, Western blot analysis, and the annexin V/propidium iodide assay with microscopic evaluation by 4',6-diamidino-2-phenylindole were conducted. Results: Dramatic phosphorylated (p)-c-Kit and p-PDGFRbeta attenuation, a modest dose- and time-dependent growth inhibition, and significant radiosensitization were observed after STI-571 treatment in view of apoptosis, although the levels of growth inhibition and increased radiosensitization were different according to cell lines. The grades of radiosensitivity corresponded to the attenuation levels of p-c-Kit and p-PDGFRbeta by STI-571, particularly to those of p-c-Kit, and the radiosensitivity was partially affected by K-ras mutation in pancreatic cancer cells. Among downstream pathways associated with c-Kit or PDGFRbeta, p-PLCgamma was more closely related to radiosensitivity compared with p-Akt1 or p-extracellular signal-regulated kinase 1. Conclusion: STI-571 enhances radiation response in pancreatic cancer cells. This effect is affected by the attenuation levels of p-c-Kit or p-PDGFRbeta, and K-ras mutation status. Among them, p-c-Kit plays more important roles in the radiosensitivity in pancreatic cancer compared with p-PDGFRbeta or K-ras mutation status.

  12. K-RAS(V12) Induces Autocrine Production of EGFR Ligands and Mediates Radioresistance Through EGFR-Dependent Akt Signaling and Activation of DNA-PKcs

    SciTech Connect

    Minjgee, Minjmaa; Toulany, Mahmoud; Kehlbach, Rainer; Giehl, Klaudia; Rodemann, H. Peter

    2011-12-01

    Purpose: It is known that postirradiation survival of tumor cells presenting mutated K-RAS is mediated through autocrine activation of epidermal growth factor receptor (EGFR). In this study the molecular mechanism of radioresistance of cells overexpressing mutated K-RAS(V12) was investigated. Methods and Materials: Head-and-neck cancer cells (FaDu) presenting wild-type K-RAS were transfected with empty vector or vector expressing mutated K-RAS(V12). The effect of K-RAS(V12) on autocrine production of EGFR ligands, activation of EGFR downstream pathways, DNA damage repair, and postirradiation survival was analyzed. Results: Conditioned medium collected from K-RAS(V12)-transfected cells enhanced activation of the phosphatidylinositol-3-kinase-Akt pathway and increased postirradiation survival of wild-type K-RAS parental cells when compared with controls. These effects were reversed by amphiregulin (AREG)-neutralizing antibody. In addition, secretion of the EGFR ligands AREG and transforming growth factor {alpha} was significantly increased upon overexpression of K-RAS(V12). Expression of mutated K-RAS(V12) resulted in an increase in radiation-induced DNA-dependent protein kinase catalytic subunit (DNA-PKcs) phosphorylation at S2056. This increase was accompanied by increased repair of DNA double-strand breaks. Abrogation of DNA-PKcs phosphorylation by serum depletion or AREG-neutralizing antibody underscored the role of autocrine production of EGFR ligands, namely, AREG, in regulating DNA-PKcs activation in K-RAS mutated cells. Conclusions: These data indicate that radioresistance of K-RAS mutated tumor cells is at least in part due to constitutive production of EGFR ligands, which mediate enhanced repair of DNA double-strand breaks through the EGFR-phosphatidylinositol-3-kinase-Akt cascade.

  13. Alterations in K-ras, APC and p53-multiple genetic pathway in colorectal cancer among Indians.

    PubMed

    Malhotra, Pooja; Anwar, Mumtaz; Nanda, Neha; Kochhar, Rakesh; Wig, Jai Dev; Vaiphei, Kim; Mahmood, Safrun

    2013-06-01

    The incidence of colorectal cancer (CRC) is increasing rapidly in Asian countries during the past few decades, but no comprehensive analysis has been done to find out the exact cause of this disease. In this study, we investigated the frequencies of mutations and expression pattern of K-ras, APC (adenomatosis polyposis coli) and p53 in tumor, adjoining and distant normal mucosa and to correlate these alterations with patients clinicopathological parameters as well as with the survival. Polymerase chain reaction (PCR)-restriction digestion was used to detect mutations in K-ras and PCR-SSCP (Single Strand Conformation Polymorphism) followed by DNA sequencing was used to detect mutations in APC and p53 genes. Immunohistochemistry was used to detect the expression pattern of K-ras, APC and p53 proteins. The frequencies of mutations of K-ras, APC and p53 in 30 tumor tissues samples were 26.7 %, 46.7 % and 20 %, respectively. Only 3.3 % of tumors contained mutations in all the three genes. The most common combination of mutation was APC and p53 whereas mutation in both p53 and K-ras were extremely rare. There was no association between the mutations and expression pattern of K-ras, APC and p53 (p>0.05). In Indians, the frequency of alterations of K-ras and APC is similar as in Westerns, whereas the frequency of p53 mutation is slightly lower. The lack of multiple mutations in tumor specimens suggests that these genetic alterations might have independent influences on CRC development and there could be multiple alternative genetic pathways to CRC in our present study cohort. PMID:23526092

  14. Discordance of Mutation Statuses of Epidermal Growth Factor Receptor and K-ras between Primary Adenocarcinoma of Lung and Brain Metastasis.

    PubMed

    Rau, Kun-Ming; Chen, Han-Ku; Shiu, Li-Yen; Chao, Tsai-Ling; Lo, Yi-Ping; Wang, Chin-Chou; Lin, Meng-Chih; Huang, Chao-Cheng

    2016-01-01

    Mutations on epidermal growth factor receptor (EGFR) of adenocarcinomas of lung have been found to be associated with increased sensitivity to EGFR tyrosine kinase inhibitors and K-ras mutations may correlate with primary resistance. We aimed to explore the discordant mutation statuses of EGFR and K-ras between primary tumors and matched brain metastases in adenocarcinomas of lung. We used a sensitive Scorpion ARMS method to analyze EGFR mutation, and Sanger sequencing followed by allele-specific real-time polymerase chain reaction to analyze K-ras mutation. Forty-nine paired tissues with both primary adenocarcinoma of lung and matched brain metastasis were collected. Thirteen patients (26.5%) were discordant for the status of EGFR between primary and metastatic sites. K-ras gene could be checked in paired specimens from 33 patients, thirteen patients (39.6%) were discordant for the status of K-ras. In primary lung adenocarcinoma, there were 14 patients of mutant EGFR had mutant K-ras synchronously. This study revealed that the status of EGFR mutation in lung adenocarcinomas is relatively consistent between primary and metastatic sites compared to K-ras mutation. However, there are still a few cases of adenocarcinoma of lung showing discordance for the status of EGFR mutation. Repeated analysis of EGFR mutation is highly recommended if tissue from metastatic or recurrent site is available for the evaluation of target therapy. PMID:27070580

  15. Discordance of Mutation Statuses of Epidermal Growth Factor Receptor and K-ras between Primary Adenocarcinoma of Lung and Brain Metastasis

    PubMed Central

    Rau, Kun-Ming; Chen, Han-Ku; Shiu, Li-Yen; Chao, Tsai-Ling; Lo, Yi-Ping; Wang, Chin-Chou; Lin, Meng-Chih; Huang, Chao-Cheng

    2016-01-01

    Mutations on epidermal growth factor receptor (EGFR) of adenocarcinomas of lung have been found to be associated with increased sensitivity to EGFR tyrosine kinase inhibitors and K-ras mutations may correlate with primary resistance. We aimed to explore the discordant mutation statuses of EGFR and K-ras between primary tumors and matched brain metastases in adenocarcinomas of lung. We used a sensitive Scorpion ARMS method to analyze EGFR mutation, and Sanger sequencing followed by allele-specific real-time polymerase chain reaction to analyze K-ras mutation. Forty-nine paired tissues with both primary adenocarcinoma of lung and matched brain metastasis were collected. Thirteen patients (26.5%) were discordant for the status of EGFR between primary and metastatic sites. K-ras gene could be checked in paired specimens from 33 patients, thirteen patients (39.6%) were discordant for the status of K-ras. In primary lung adenocarcinoma, there were 14 patients of mutant EGFR had mutant K-ras synchronously. This study revealed that the status of EGFR mutation in lung adenocarcinomas is relatively consistent between primary and metastatic sites compared to K-ras mutation. However, there are still a few cases of adenocarcinoma of lung showing discordance for the status of EGFR mutation. Repeated analysis of EGFR mutation is highly recommended if tissue from metastatic or recurrent site is available for the evaluation of target therapy. PMID:27070580

  16. Inhibition of Acid Sphingomyelinase Depletes Cellular Phosphatidylserine and Mislocalizes K-Ras from the Plasma Membrane.

    PubMed

    Cho, Kwang-Jin; van der Hoeven, Dharini; Zhou, Yong; Maekawa, Masashi; Ma, Xiaoping; Chen, Wei; Fairn, Gregory D; Hancock, John F

    2015-01-01

    K-Ras must localize to the plasma membrane for biological activity; thus, preventing plasma membrane interaction blocks K-Ras signal output. Here we show that inhibition of acid sphingomyelinase (ASM) mislocalizes both the K-Ras isoforms K-Ras4A and K-Ras4B from the plasma membrane to the endomembrane and inhibits their nanoclustering. We found that fendiline, a potent ASM inhibitor, reduces the phosphatidylserine (PtdSer) and cholesterol content of the inner plasma membrane. These lipid changes are causative because supplementation of fendiline-treated cells with exogenous PtdSer rapidly restores K-Ras4A and K-Ras4B plasma membrane binding, nanoclustering, and signal output. Conversely, supplementation with exogenous cholesterol restores K-Ras4A but not K-Ras4B nanoclustering. These experiments reveal different operational pools of PtdSer on the plasma membrane. Inhibition of ASM elevates cellular sphingomyelin and reduces cellular ceramide levels. Concordantly, delivery of recombinant ASM or exogenous ceramide to fendiline-treated cells rapidly relocalizes K-Ras4B and PtdSer to the plasma membrane. K-Ras4B mislocalization is also recapitulated in ASM-deficient Neimann-Pick type A and B fibroblasts. This study identifies sphingomyelin metabolism as an indirect regulator of K-Ras4A and K-Ras4B signaling through the control of PtdSer plasma membrane content. It also demonstrates the critical and selective importance of PtdSer to K-Ras4A and K-Ras4B plasma membrane binding and nanoscale spatial organization. PMID:26572827

  17. Inhibition of Acid Sphingomyelinase Depletes Cellular Phosphatidylserine and Mislocalizes K-Ras from the Plasma Membrane

    PubMed Central

    Cho, Kwang-jin; van der Hoeven, Dharini; Zhou, Yong; Maekawa, Masashi; Ma, Xiaoping; Chen, Wei

    2015-01-01

    K-Ras must localize to the plasma membrane for biological activity; thus, preventing plasma membrane interaction blocks K-Ras signal output. Here we show that inhibition of acid sphingomyelinase (ASM) mislocalizes both the K-Ras isoforms K-Ras4A and K-Ras4B from the plasma membrane to the endomembrane and inhibits their nanoclustering. We found that fendiline, a potent ASM inhibitor, reduces the phosphatidylserine (PtdSer) and cholesterol content of the inner plasma membrane. These lipid changes are causative because supplementation of fendiline-treated cells with exogenous PtdSer rapidly restores K-Ras4A and K-Ras4B plasma membrane binding, nanoclustering, and signal output. Conversely, supplementation with exogenous cholesterol restores K-Ras4A but not K-Ras4B nanoclustering. These experiments reveal different operational pools of PtdSer on the plasma membrane. Inhibition of ASM elevates cellular sphingomyelin and reduces cellular ceramide levels. Concordantly, delivery of recombinant ASM or exogenous ceramide to fendiline-treated cells rapidly relocalizes K-Ras4B and PtdSer to the plasma membrane. K-Ras4B mislocalization is also recapitulated in ASM-deficient Neimann-Pick type A and B fibroblasts. This study identifies sphingomyelin metabolism as an indirect regulator of K-Ras4A and K-Ras4B signaling through the control of PtdSer plasma membrane content. It also demonstrates the critical and selective importance of PtdSer to K-Ras4A and K-Ras4B plasma membrane binding and nanoscale spatial organization. PMID:26572827

  18. K-Ras4B proteins are expressed in the nucleolus: Interaction with nucleolin.

    PubMed

    Birchenall-Roberts, Maria C; Fu, Tao; Kim, Soo-Gyung; Huang, Ying K; Dambach, Michael; Resau, James H; Ruscetti, Francis W

    2006-09-22

    Kirsten Ras4B (K-Ras4B) is a potent onco-protein that is expressed in the majority of human cell types and is frequently mutated in carcinomas. K-Ras4B, like other members of the Ras family of proteins, is considered to be a cytoplasmic protein that must be localized to the plasma membrane for activation. Here, using confocal microscopy and biochemical analysis, we show that K-Ras4B, but not H-Ras or the closely related K-Ras4A, is also present in the nucleoli of normal and transformed cells. Subcellular fractionation and immunostaining show that K-Ras4B is located not only in the cytoplasm, but also in the nucleolar compartment. Modification of a C-terminal hexa-lysine motif unique to K-Ras4B results in exclusively cytoplasmic forms of the protein. Nucleolin, a pleiotropic regulator of cellular processes, including transcriptional regulation, is also characterized by a nucleolar-like nuclear appearance. We show that K-Ras4B and nucleolin co-localize within the nucleus and that nucleolin physically associates with K-Ras4B. Inhibition of K-Ras4B/nucleolin association blocked nucleolar localization of K-Ras4B. Using siRNA to knockdown the expression of nucleolin eliminated the nucleolar localization of K-Ras4B and significantly repressed the activation of the well-characterized K-Ras4B transcriptional target Ap-1, but stimulated Elk1. These data provide evidence of a nucleolar localization of K-Ras4B and describe a functional association between K-Ras4B and nucleolin. PMID:16889753

  19. K-Ras4B proteins are expressed in the nucleolus: Interaction with nucleolin

    SciTech Connect

    Birchenall-Roberts, Maria C. . E-mail: birchena@mail.ncifcrf.gov; Fu, Tao; Kim, Soo-Gyung; Huang, Ying K.; Dambach, Michael; Resau, James H.; Ruscetti, Francis W.

    2006-09-22

    Kirsten Ras4B (K-Ras4B) is a potent onco-protein that is expressed in the majority of human cell types and is frequently mutated in carcinomas. K-Ras4B, like other members of the Ras family of proteins, is considered to be a cytoplasmic protein that must be localized to the plasma membrane for activation. Here, using confocal microscopy and biochemical analysis, we show that K-Ras4B, but not H-Ras or the closely related K-Ras4A, is also present in the nucleoli of normal and transformed cells. Subcellular fractionation and immunostaining show that K-Ras4B is located not only in the cytoplasm, but also in the nucleolar compartment. Modification of a C-terminal hexa-lysine motif unique to K-Ras4B results in exclusively cytoplasmic forms of the protein. Nucleolin, a pleiotropic regulator of cellular processes, including transcriptional regulation, is also characterized by a nucleolar-like nuclear appearance. We show that K-Ras4B and nucleolin co-localize within the nucleus and that nucleolin physically associates with K-Ras4B. Inhibition of K-Ras4B/nucleolin association blocked nucleolar localization of K-Ras4B. Using siRNA to knockdown the expression of nucleolin eliminated the nucleolar localization of K-Ras4B and significantly repressed the activation of the well-characterized K-Ras4B transcriptional target Ap-1, but stimulated Elk1. These data provide evidence of a nucleolar localization of K-Ras4B and describe a functional association between K-Ras4B and nucleolin.

  20. Deletion of Pim kinases elevates the cellular levels of reactive oxygen species and sensitizes to K-Ras-induced cell killing.

    PubMed

    Song, J H; An, N; Chatterjee, S; Kistner-Griffin, E; Mahajan, S; Mehrotra, S; Kraft, A S

    2015-07-01

    The Pim protein kinases contribute to transformation by enhancing the activity of oncogenic Myc and Ras, which drives significant metabolic changes during tumorigenesis. In this report, we demonstrate that mouse embryo fibroblasts (MEFs) lacking all three isoforms of Pim protein kinases, triple knockout (TKO), cannot tolerate the expression of activated K-Ras (K-Ras(G12V)) and undergo cell death. Transduction of K-Ras(G12V) into these cells markedly increased the level of cellular reactive oxygen species (ROS). The addition of N-acetyl cysteine attenuated ROS production and reversed the cytotoxic effects of K-Ras(G12V) in the TKO MEFs. The altered cellular redox state caused by the loss of Pim occurred as a result of lower levels of metabolic intermediates in the glycolytic and pentose phosphate pathways as well as abnormal mitochondrial oxidative phosphorylation. TKO MEFs exhibit reduced levels of superoxide dismutase (Sod), glutathione peroxidase 4 (Gpx4) and peroxiredoxin 3 (Prdx3) that render them susceptible to killing by K-Ras(G12V)-mediated ROS production. In contrast, the transduction of c-Myc into TKO cells can overcome the lack of Pim protein kinases by regulating cellular metabolism and Sod2. In the absence of the Pim kinases, c-Myc transduction permitted K-Ras(G12V)-induced cell growth by decreasing Ras-induced cellular ROS levels. These results demonstrate that the Pim protein kinases have an important role in regulating cellular redox, metabolism and K-Ras-stimulated cell growth. PMID:25241892

  1. TP53 and Let-7a micro-RNA Regulate K-Ras Activity in HCT116 Colorectal Cancer Cells

    PubMed Central

    Luu, Carrie; Heinrich, Eileen L.; Duldulao, Marjun; Arrington, Amanda K.; Fakih, Marwan; Garcia-Aguilar, Julio; Kim, Joseph

    2013-01-01

    Recent reports have indicated that KRAS and TP53 mutations predict response to therapy in colorectal cancer. However, little is known about the relationship between these two common genetic alterations. Micro-RNAs (miRNAs), a class of noncoding RNA implicated in cellular processes, have been increasingly linked to KRAS and TP53. We hypothesized that lethal-7a (let-7a) miRNA regulates KRAS through TP53. To investigate the relationship between KRAS, TP53, and let-7a, we used HCT116 KRASmut human colorectal cancer cells with four different genotypic modifications in TP53 (TP53−/−, TP53+/−, TP53mut/+, and TP53mut/−). Using these cells we observed that K-Ras activity was higher in cells with mutant or knocked out TP53 alleles, suggesting that wild-type TP53 may suppress K-Ras activity. Let-7a was present in HCT116 KRASmut cells, though there was no correlation between let-7a level and TP53 genotype status. To explore how let-7a may regulate K-Ras in the different TP53 genotype cells we used let-7a inhibitor and demonstrated increased K-Ras activity across all TP53, thus corroborating prior reports that let-7a regulates K-Ras. To assess potential clinical implications of this regulatory network, we examined the influence of TP53 genotype and let-7a inhibition on colon cancer cell survival following chemoradiation therapy (CRT). We observed that cells with complete loss of wild-type TP53 alleles (−/− or −/mut) were resistant to CRT following treatment with 5-fluorouracil and radiation. Further increase in K-Ras activity with let-7a inhibition did not impact survival in these cells. In contrast, cells with single or double wild-type TP53 alleles were moderately responsive to CRT and exhibited resistance when let-7a was inhibited. In summary, our results show a complex regulatory system involving TP53, KRAS, and let-7a. Our results may provide clues to understand and target these interactions in colorectal cancer. PMID:23936455

  2. Regulation of K-Ras4B Membrane Binding by Calmodulin.

    PubMed

    Sperlich, Benjamin; Kapoor, Shobhna; Waldmann, Herbert; Winter, Roland; Weise, Katrin

    2016-07-12

    K-Ras4B is a membrane-bound small GTPase with a prominent role in cancer development. It contains a polybasic farnesylated C-terminus that is required for the correct localization and clustering of K-Ras4B in distinct membrane domains. PDEδ and the Ca(2+)-binding protein calmodulin (CaM) are known to function as potential binding partners for farnesylated Ras proteins. However, they differ in the number of interaction sites with K-Ras4B, leading to different modes of interaction, and thus affect the subcellular distribution of K-Ras4B in different ways. Although it is clear that Ca(2+)-bound CaM can play a role in the dynamic spatial cycle of K-Ras4B in the cell, the exact molecular mechanism is only partially understood. In this biophysical study, we investigated the effect of Ca(2+)/CaM on the interaction of GDP- and GTP-loaded K-Ras4B with heterogeneous model biomembranes by using a combination of different spectroscopic and imaging techniques. The results show that Ca(2+)/CaM is able to extract K-Ras4B from negatively charged membranes in a nucleotide-independent manner. Moreover, the data demonstrate that the complex of Ca(2+)/CaM and K-Ras4B is stable in the presence of anionic membranes and shows no membrane binding. Finally, the influence of Ca(2+)/CaM on the interaction of K-Ras4B with membranes is compared with that of PDEδ, which was investigated in a previous study. Although both CaM and PDEδ exhibit a hydrophobic binding pocket for farnesyl, they have different effects on membrane binding of K-Ras4B and hence should be capable of regulating K-Ras4B plasma membrane localization in the cell. PMID:27410739

  3. A novel combination of K-ras and myc amplification accompanied by point mutational activation of K-ras in a human lung cancer.

    PubMed Central

    Taya, Y; Hosogai, K; Hirohashi, S; Shimosato, Y; Tsuchiya, R; Tsuchida, N; Fushimi, M; Sekiya, T; Nishimura, S

    1984-01-01

    Amplifications of two oncogenes, c-K-ras-2 and c-myc, were found in a human lung giant cell carcinoma (LGCC) Lu-65, which is maintained in nude mice. The extent of c-K-ras-2 and myc amplifications were estimated to be 10- and 8-fold, respectively, by means of the Southern hybridization procedure. In addition, NIH3T3 cells were transformed by transfection of Lu-65 DNA and the transforming gene was identified as c-K-ras-2. c-K-ras-2 genes were cloned from a gene library of Lu-65 and a single point mutation causing a substitution of cysteine for glycine in codon 12 was found by DNA sequencing. It was concluded that the amplification of the c-myc and c-K-ras-2 genes are accompanied by point mutational activation of c-K-ras-2 in the human LGCC Lu-65. This is the first report of multiple gene amplification accompanied by a point mutation of oncogenes in human cancer cells, providing further support for the idea that co-operation of at least two activated cellular oncogenes is required for carcinogenesis. Images Fig. 1. Fig. 2. Fig. 3. Fig. 5. PMID:6098458

  4. CaM interaction and Ser181 phosphorylation as new K-Ras signaling modulators

    PubMed Central

    Alvarez-Moya, Blanca; Barceló, Carles; Tebar, Francesc; Jaumot, Montserrat

    2011-01-01

    The small G-protein Ras was the first oncogene to be identified and has a very important contribution to human cancer development (20–23% prevalence). K-RasB, one of the members of the Ras family, is the one that is most mutated and plays a prominent role in pancreatic, colon and lung cancer development. Ras proteins are membrane bound GTPases that cycle between inactive, GDP-bound and active, GTP-bound, states. Most of the research into K-RasB activity regulation has focused on the analysis of how GTP-exchange factors (GEFs) and GTPase activating proteins (GAPs) are regulated by external and internal signals. In contrast, oncogenic K-RasB has a very low GTPase activity and furthermore is not deactivated by GAPs. Consequently, the consensus was that activity of oncogenic K-RasB was not modulated. In this extra view we recapitulate some recent data showing that calmodulin binding to K-RasB inhibits phosphorylation of K-RasB at Ser181, near to the membrane anchoring domain, modulating signaling of both non-oncogenic and oncogenic K-RasB. This may be relevant to normal cell physiology, but also opens new therapeutic perspectives for the inhibition of oncogenic K-RasB signaling in tumors. PMID:21776410

  5. K-ras gene mutation in gall bladder carcinomas and dysplasia.

    PubMed Central

    Ajiki, T; Fujimori, T; Onoyama, H; Yamamoto, M; Kitazawa, S; Maeda, S; Saitoh, Y

    1996-01-01

    Epithelial dysplasia of gall bladder is an important precancerous lesion of gall bladder carcinogenesis. To investigate the frequency of K-ras gene mutation in gall bladder carcinoma and dysplasia, K-ras codon 12 mutations were investigated by the polymerase chain reaction/restriction enzyme based method following direct sequencing. Mutation was detected in 59% (30 of 51) of gall bladder carcinomas, in 73% (8 of 11) of gall bladder dysplasia in gall stone cases, and in 0% of the normal gall bladder epithelium. There was, however, no correlation between K-ras mutation and clinicopathological factors of gall bladder carcinoma. K-ras gene mutation occurs even in gall bladder dysplasia at an incidence similar to that in carcinomas, suggesting that testing for K-ras gene mutation may prove useful as an adjunct to bile cytological or biopsy analysis. Images Figure 1 Figure 2 Figure 3 PMID:8675098

  6. Analysis of K-Ras Nuclear Expression in Fibroblasts and Mesangial Cells

    PubMed Central

    Fuentes-Calvo, Isabel; Blázquez-Medela, Ana M.; Santos, Eugenio; López-Novoa, José M.; Martínez-Salgado, Carlos

    2010-01-01

    Background Ras GTPases are considered cytoplasmic proteins that must be localized to cell membranes for activation, and there are few evidences of the presence of any Ras isoform in nuclei of eukaryotic cells. Methodology/Principal Findings Using conventional antibodies and inmunocytochemistry, differential centrifugation and western blot, we have observed the putative presence of K-Ras isoform in the nuclei of fibroblasts and mesangial cells. In order to avoid cross-reactions with other Ras isoforms, and using antibodies against K-Ras (R-3400, H3845-M01, sc-30) or pan-Ras (05-516, OP40) in cells that only expressed the K-Ras isoform (fibroblasts obtained from H-ras−/−,N-ras−/− mice) we also detected some nuclear positive expression. To further probe the identity of nuclear K-Ras, we have generated K-Ras knockout (K-ras−/−) embrionary fibroblasts by mating of K-ras+/− heterozygote mice. Using specific antibodies, only H- and N-Ras isoforms were observed in the cytoplasm of K-ras−/− fibroblasts. However, both K-Ras4A and K-Ras4B positive signals were detected by immunocytochemistry and Western blot with two commercial antibodies (sc-522 and sc-521 against each isoforms, respectively) in both cytoplasm and nuclei from K-ras−/− fibroblasts. Conclusions/Significance We show that the presence of K-Ras4B in fibroblast nuclei, already described by other authors, is probably due to a cross-reaction of the antibody with an undetermined nucleolar protein. Although this study also shows the possible nuclear expression of K-Ras isoform in fibroblasts or in mesangial cells, it also reveals the importance of being cautious in these studies about distribution of protein isoforms due to some important limitations imposed by the unspecificity of the antibodies or contaminations in cellular preparations. PMID:20090846

  7. Synergistic effects of sorafenib in combination with gemcitabine or pemetrexed in lung cancer cell lines with K-ras mutations

    PubMed Central

    Wang, Shu; Su, Zeng-feng; Yuan, Yuan

    2016-01-01

    K-ras is currently accepted as the most frequently mutated oncogene in non-small cell lung cancer (NSCLC, including squamous carcinoma, adenocarcinoma, and large cell carcinoma). NSCLC patients with the K-ras mutation appear to be refractory to the majority of systemic therapies. In the present study, the in vitro antitumor effects and correlated molecular mechanisms of sorafenib combined with gemcitabine or pemetrexed were explored in the K-ras mutation-positive NSCLC A549 cell line. Sorafenib was seen to exhibit dose-dependent growth inhibition in the A549 cells, while sorafenib combined with pemetrexed demonstrated a greater synergism compared with sorafenib combined with gemcitabine. Sorafenib arrested the cell cycle at the G1 phase, while gemcitabine and pemetrexed caused arrest at the S phase. The molecular mechanism of this synergism was due to the downstream signalling pathways, which were efficiently suppressed by sorafenib, therefore increasing the incidence of the entry of the chemotherapeutic drugs into the apoptotic pathways. Moreover, sorafenib and pemetrexed demonstrated stronger synergism, demonstrating that inhibiting the Ras/Raf/Mek/Erk and Ras/PI3K/Akt pathways concurrently may achieve improved antitumor effects. PMID:27095937

  8. Bi-transgenic Mice Reveal that K-rasVal12 Augments a p53-independent Apoptosis When Small Intestinal Villus Enterocytes Reenter the Cell Cycle

    PubMed Central

    Coopersmith, Craig M.; Chandrasekaran, Chitra; McNevin, M. Shane; Gordon, Jeffrey I.

    1997-01-01

    Studies in cell culture systems have indicated that oncogenic forms of Ras can affect apoptosis. Activating mutations of Ras occur in ∼30% of all human tumors and 50% of colorectal carcinomas. Since these mutations appear at early or intermediate stages in multistep journeys to neoplasia, an effect on apoptosis may help determine whether initiated cells progress towards a more neoplastic state. We have tested the effects of K-rasVal12 on apoptosis in transgenic mice. A lineage-specific promoter was used to direct expression of human K-rasVal12, with or without wild-type (wt) or mutant SV-40 T antigens (TAg), in postmitotic villus enterocytes, the principal cell type of the small intestinal epithelium. Enterocytes can be induced to reenter the cell cycle by TAgWt. Reentry is dependent upon the ability of TAg to bind pRB and is associated with a p53-independent apoptosis. Analyses of K-rasVal12 × TAgWt bi-transgenic animals indicated that K-rasVal12 can enhance this apoptosis threefold but only in cycling cells; increased apoptosis does not occur when K-rasVal12 is expressed alone or with a TAg containing Glu107,108→ Lys107,108 substitutions that block its ability to bind pRB. Analysis of bi-transgenic K-rasVal12 × TAgWt mice homozygous for wild-type or null p53 alleles established that the enhancement of apoptosis occurs through a p53-independent mechanism, is not attributable to augmented proliferation or to an increase in abortive cell cycle reentry (compared to TAgWt mice), and is not associated with detectable changes in the crypt–villus patterns of expression of apoptotic regulators (Bcl-2, Bcl-xL, Bak, and Bax) or mediators of epithelial cell–matrix interactions and survival (e.g., α5β1 integrin and its ligand, fibronectin). Coexpression of K-rasVal12 and TAgWt produces dysplasia. The K-rasVal12-augmented apoptosis is unrelated to this dysplasia; enhanced apoptosis is also observed in cycling nondysplastic enterocytes that produce K-rasVal12 and a

  9. Nitrative and oxidative DNA damage caused by K-ras mutation in mice

    SciTech Connect

    Ohnishi, Shiho; Saito, Hiromitsu; Suzuki, Noboru; Ma, Ning; Hiraku, Yusuke; Murata, Mariko; Kawanishi, Shosuke

    2011-09-23

    Highlights: {yields} Mutated K-ras in transgenic mice caused nitrative DNA damage, 8-nitroguanine. {yields} The mutagenic 8-nitroguanine seemed to be generated by iNOS via Ras-MAPK signal. {yields} Mutated K-ras produces additional mutagenic lesions, as a new oncogenic role. -- Abstract: Ras mutation is important for carcinogenesis. Carcinogenesis consists of multi-step process with mutations in several genes. We investigated the role of DNA damage in carcinogenesis initiated by K-ras mutation, using conditional transgenic mice. Immunohistochemical analysis revealed that mutagenic 8-nitroguanine and 8-oxo-7,8-dihydro-2'-deoxyguanosine (8-oxodG) were apparently formed in adenocarcinoma caused by mutated K-ras. 8-Nitroguanine was co-localized with iNOS, eNOS, NF-{kappa}B, IKK, MAPK, MEK, and mutated K-ras, suggesting that oncogenic K-ras causes additional DNA damage via signaling pathway involving these molecules. It is noteworthy that K-ras mutation mediates not only cell over-proliferation but also the accumulation of mutagenic DNA lesions, leading to carcinogenesis.

  10. IL6 Blockade Reprograms the Lung Tumor Microenvironment to Limit the Development and Progression of K-ras-Mutant Lung Cancer.

    PubMed

    Caetano, Mauricio S; Zhang, Huiyuan; Cumpian, Amber M; Gong, Lei; Unver, Nese; Ostrin, Edwin J; Daliri, Soudabeh; Chang, Seon Hee; Ochoa, Cesar E; Hanash, Samir; Behrens, Carmen; Wistuba, Ignacio I; Sternberg, Cinthya; Kadara, Humam; Ferreira, Carlos Gil; Watowich, Stephanie S; Moghaddam, Seyed Javad

    2016-06-01

    Activating mutations of K-ras are the most common oncogenic alterations found in lung cancer. Unfortunately, attempts to target K-ras-mutant lung tumors have thus far failed, clearly indicating the need for new approaches in patients with this molecular profile. We have previously shown NF-κB activation, release of IL6, and activation of its responsive transcription factor STAT3 in K-ras-mutant lung tumors, which was further amplified by the tumor-enhancing effect of chronic obstructive pulmonary disease (COPD)-type airway inflammation. These findings suggest an essential role for this inflammatory pathway in K-ras-mutant lung tumorigenesis and its enhancement by COPD. Therefore, here we blocked IL6 using a monoclonal anti-IL6 antibody in a K-ras-mutant mouse model of lung cancer in the absence or presence of COPD-type airway inflammation. IL6 blockade significantly inhibited lung cancer promotion, tumor cell-intrinsic STAT3 activation, tumor cell proliferation, and angiogenesis markers. Moreover, IL6 inhibition reduced expression of protumor type 2 molecules (arginase 1, Fizz 1, Mgl, and IDO), number of M2-type macrophages and granulocytic myeloid-derived suppressor cells, and protumor T-regulatory/Th17 cell responses. This was accompanied by increased expression of antitumor type 1 molecule (Nos2), and antitumor Th1/CD8 T-cell responses. Our study demonstrates that IL6 blockade not only has direct intrinsic inhibitory effect on tumor cells, but also reeducates the lung microenvironment toward an antitumor phenotype by altering the relative proportion between protumor and antitumor immune cells. This information introduces IL6 as a potential druggable target for prevention and treatment of K-ras-mutant lung tumors. Cancer Res; 76(11); 3189-99. ©2016 AACR. PMID:27197187

  11. Lead identification for the K-Ras protein: virtual screening and combinatorial fragment-based approaches

    PubMed Central

    Pathan, Akbar Ali Khan; Panthi, Bhavana; Khan, Zahid; Koppula, Purushotham Reddy; Alanazi, Mohammed Saud; Sachchidanand; Parine, Narasimha Reddy; Chourasia, Mukesh

    2016-01-01

    Objective Kirsten rat sarcoma (K-Ras) protein is a member of Ras family belonging to the small guanosine triphosphatases superfamily. The members of this family share a conserved structure and biochemical properties, acting as binary molecular switches. The guanosine triphosphate-bound active K-Ras interacts with a range of effectors, resulting in the stimulation of downstream signaling pathways regulating cell proliferation, differentiation, and apoptosis. Efforts to target K-Ras have been unsuccessful until now, placing it among high-value molecules against which developing a therapy would have an enormous impact. K-Ras transduces signals when it binds to guanosine triphosphate by directly binding to downstream effector proteins, but in case of guanosine diphosphate-bound conformation, these interactions get disrupted. Methods In the present study, we targeted the nucleotide-binding site in the “on” and “off” state conformations of the K-Ras protein to find out suitable lead compounds. A structure-based virtual screening approach has been used to screen compounds from different databases, followed by a combinatorial fragment-based approach to design the apposite lead for the K-Ras protein. Results Interestingly, the designed compounds exhibit a binding preference for the “off” state over “on” state conformation of K-Ras protein. Moreover, the designed compounds’ interactions are similar to guanosine diphosphate and, thus, could presumably act as a potential lead for K-Ras. The predicted drug-likeness properties of these compounds suggest that these compounds follow the Lipinski’s rule of five and have tolerable absorption, distribution, metabolism, excretion and toxicity values. Conclusion Thus, through the current study, we propose targeting only “off” state conformations as a promising strategy for the design of reversible inhibitors to pharmacologically inhibit distinct conformations of K-Ras protein. PMID:27217775

  12. Combined Inactivation of MYC and K-Ras Oncogenes Reverses Tumorigenesis in Lung Adenocarcinomas and Lymphomas

    PubMed Central

    Koh, Shan; Komatsubara, Kim; Chen, Joy; Horng, George; Bellovin, David I.; Giuriato, Sylvie; Wang, Craig S.; Whitsett, Jeffrey A.; Felsher, Dean W.

    2008-01-01

    Background Conditional transgenic models have established that tumors require sustained oncogene activation for tumor maintenance, exhibiting the phenomenon known as “oncogene-addiction.” However, most cancers are caused by multiple genetic events making it difficult to determine which oncogenes or combination of oncogenes will be the most effective targets for their treatment. Methodology/Principal Findings To examine how the MYC and K-rasG12D oncogenes cooperate for the initiation and maintenance of tumorigenesis, we generated double conditional transgenic tumor models of lung adenocarcinoma and lymphoma. The ability of MYC and K-rasG12D to cooperate for tumorigenesis and the ability of the inactivation of these oncogenes to result in tumor regression depended upon the specific tissue context. MYC-, K-rasG12D- or MYC/K-rasG12D-induced lymphomas exhibited sustained regression upon the inactivation of either or both oncogenes. However, in marked contrast, MYC-induced lung tumors failed to regress completely upon oncogene inactivation; whereas K-rasG12D-induced lung tumors regressed completely. Importantly, the combined inactivation of both MYC and K-rasG12D resulted more frequently in complete lung tumor regression. To account for the different roles of MYC and K-rasG12D in maintenance of lung tumors, we found that the down-stream mediators of K-rasG12D signaling, Stat3 and Stat5, are dephosphorylated following conditional K-rasG12D but not MYC inactivation. In contrast, Stat3 becomes dephosphorylated in lymphoma cells upon inactivation of MYC and/or K-rasG12D. Interestingly, MYC-induced lung tumors that failed to regress upon MYC inactivation were found to have persistent Stat3 and Stat5 phosphorylation. Conclusions/Significance Taken together, our findings point to the importance of the K-Ras and associated down-stream Stat effector pathways in the initiation and maintenance of lymphomas and lung tumors. We suggest that combined targeting of oncogenic

  13. The brain microenvironment negatively regulates miRNA-768-3p to promote K-ras expression and lung cancer metastasis

    PubMed Central

    Subramani, Arasukumar; Alsidawi, Samer; Jagannathan, Sajjeev; Sumita, Kazutaka; Sasaki, Atsuo T.; Aronow, Bruce; Warnick, Ronald E.; Lawler, Sean; Driscoll, James J.

    2013-01-01

    The brain microenvironment promotes metastasis through mechanisms that remain elusive. Co-culture of lung cancer cells with astrocytes - the most abundant cell type within the metastatic brain niche – lead to downregulation of miRNA-768-3p which drives K-ras expression and key signaling pathways, enhances cell viability and promotes chemotherapeutic resistance. Vector-based forced expression of miRNA-768-3p complementary sequence or a chemically-engineered miRNA-768-3p inhibitor recapitulated the astrocyte effect to increase tumor cell viability. The miRNA-768-3p inhibitor targeted the K-ras 3′-UTR as demonstrated by increased luminescence from a luciferase reporter and strikingly increased the K-ras protein and the downstream effectors ERK1/2 and B-Raf. miRNA-768-3p was reduced in patient brain metastases compared to normal brain tissue and was lower in patient tissue from brain metastases compared to same-patient primary tumour tissue. The brain microenvironment negatively regulates miRNA-768-3p to enhance K-ras and promote metastasis. We propose that therapeutic replacement of the metastasis suppressor miRNA-768-3p holds clinical promise. PMID:23928793

  14. K-Ras(V14I) -induced Noonan syndrome predisposes to tumour development in mice.

    PubMed

    Hernández-Porras, Isabel; Schuhmacher, Alberto J; Garcia-Medina, Raquel; Jiménez, Beatriz; Cañamero, Marta; de Martino, Alba; Guerra, Carmen

    2016-06-01

    The Noonan syndrome (NS) is an autosomal dominant genetic disorder characterized by short stature, craniofacial dysmorphism, and congenital heart defects. A significant proportion of NS patients may also develop myeloproliferative disorders (MPDs), including juvenile myelomonocytic leukaemia (JMML). Surprisingly, scarce information is available in relation to other tumour types in these patients. We have previously developed and characterized a knock-in mouse model that carries one of the most frequent KRAS-NS-related mutations, the K-Ras(V14I) substitution, which recapitulates most of the alterations described in NS patients, including MPDs. The K-Ras(V14I) mutation is a mild activating K-Ras protein; thus, we have used this model to study tumour susceptibility in comparison with mice expressing the classical K-Ras(G12V) oncogene. Interestingly, our studies have shown that these mice display a generalized tumour predisposition and not just MPDs. In fact, we have observed that the K-Ras(V14I) mutation is capable of cooperating with the p16Ink4a/p19Arf and Trp53 tumour suppressors, as well as with other risk factors such as pancreatitis, thereby leading to a higher cancer incidence. In conclusion, our results illustrate that the K-Ras(V14I) activating protein is able to induce cancer, although at a much lower level than the classical K-Ras(G12V) oncogene, and that it can be significantly modulated by both genetic and non-genetic events. Copyright © 2016 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd. PMID:27174785

  15. k-RAS mutations in non-small cell lung cancer patients treated with TKIs among smokers and non-smokers: a meta-analysis

    PubMed Central

    Lu, Hui-Yu

    2016-01-01

    Aim of the study Recent studies have suggested that k-RAS mutations are related to the response to epidermal growth factor receptor (EGFR) tyrosine-kinase inhibitions (TKIs) in advanced non-small cell lung cancer (NSCLC) treatment. The aim of this meta-analysis was to assess the relationship between smoking history and k-RAS mutations in NSCLC treated with TKIs. Material and methods We searched MEDLINE and Web of Science up to 15 March 2014. The pooled relative risk (RR) was estimated by using fixed effect model or random effect model, according to heterogeneity between studies. We also carried out power analyses. Results We identified 12 studies with 1193 patients, including 196 patients (16.4%) with k-RAS mutations. The pooled k-RAS mutations incidence was 22.8% (174/764) in patients with smoke expose vs. 5.4% (23/429) in those with no smoke exposure. The pooled RR was 2.991 (95% CI: 1.884–4.746; Z = 4.65, p = 0.000). No publication bias was found (Begg's test: z = 1.09, p = 0.274 and Egger's test: t = 1.38, p = 0.201). In subgroup analyses, the pooled RR was 3.336 (95% CI: 1.925–5.779; Z = 4.30, p = 0.000) in the Caucasian subgroup, while in the Asian subgroup the pooled RR was 2.093 (95% CI: 0.909–4.822; Z = 1.73, p = 0.083), but the sample size was underpowered (0.465). Conclusions The current meta-analysis found that smoking was related to increased incidence of k-RAS mutations in non-small cell lung cancer treated with TKIs. This may be further evidence that smoking will lead to a worse prognosis in NSCLC patients treated with TKIs. PMID:27358590

  16. K-Ras Mutations in Non-Small-Cell Lung Cancer: Prognostic and Predictive Value

    PubMed Central

    D'Arcangelo, Manolo; Cappuzzo, Federico

    2012-01-01

    Non-small-cell lung cancer (NSCLC) is a heterogeneous disease due to the presence of different clinically relevant molecular subtypes. Until today, several biological events have been identified in lung adenocarcinoma, including epidermal growth factor receptor (EGFR) mutations and anaplastic lymphoma kinase (ALK) translocations, offering new hopes to patients with metastatic disease. Unfortunately, in approximately 50% of adenocarcinoma and for those harbouring K-RAS mutations, the most frequent mutation in Caucasian lung adenocarcinoma, so far no specific drug demonstrated efficacy. The rat sarcoma (RAS) genes, including H-RAS, K-RAS, and N-RAS, encode a family of proteins regulating cell growth, differentiation, and apoptosis. K-RAS mutations are present in 20–30% of NSCLC and occur most commonly, but not exclusively, in adenocarcinoma histology and life-long smokers. Although in colorectal cancer patients K-RAS mutations represent a validated negative predictive biomarker for treatment with anti-EGFR monoclonal antibodies, their role in selecting specific treatment for NSCLC patients remains undefined. Aim of the present paper is to critically analyze the prognostic and predictive value of K-RAS mutations in NSCLC.

  17. Characterization of a novel oncogenic K-ras mutation in colon cancer

    SciTech Connect

    Akagi, Kiwamu . E-mail: akagi@cancer-c.pref.saitama.jp; Uchibori, Ryosuke; Yamaguchi, Kensei; Kurosawa, Keiko; Tanaka, Yoichiro; Kozu, Tomoko

    2007-01-19

    Activating mutations of RAS are frequently observed in subsets of human cancers, indicating that RAS activation is involved in tumorigenesis. Here, we identified and characterized a novel G to T transversion mutation of the K-ras gene at the third position of codon 19 (TTG) which substituted phenylalanine for leucine in 3 primary colon carcinomas. Biological and biochemical activity was examined using transformed NIH3T3 cells expressing mutant or wild-type K-ras. Transformants harboring the K-ras mutation at codon 19 showed proliferative capacity under serum-starved conditions, less contact inhibition, anchorage-independent growth, tumorigenicity in nude mice and elevation of active Ras-GTP levels. These results indicated that this novel mutation possesses high oncogenic activity.

  18. K-ras mutations in beryllium-induced mouse lung tumors

    SciTech Connect

    Belinsky, S.A.; Mitchell, C.E.

    1994-11-01

    Previous studies at ITRI have shown that single, nose-only exposure of F344/N rats to beryllium metal (Be) produced a 64% incidence of lung tumors over the lifetime of the rat. Long tumors induced by Be metal were subsequently analyzed for alterations in the K-ras and p53 genes. Mutation of the K-ras gene was both a rare (2 of 24 tumors) and late event in Be-induced carcinogenesis. In addition, no mutations were detected in exons 5 - 8 of the p53 gene. These results indicated that the mechanisms underlying the development of Be-induced lung cancer in rats did not involve gene dysfunction commonly associated with human non-small-cell lung cancer. The purpose of this study was to determine and compare the prevalence and specificity for mutation of the K-ras gene in lung tumors induced in the A/J mouse by Be to mutations in spontaneous tumors.

  19. Prevalence of K-Ras mutations in hepatocellular carcinoma: A Turkish Oncology Group pilot study

    PubMed Central

    TURHAL, NAZIM SERDAR; SAVAŞ, BERNA; ÇOŞKUN, ÖZNUR; BAŞ, EMINE; KARABULUT, BÜLENT; NART, DENIZ; KORKMAZ, TANER; YAVUZER, DILEK; DEMIR, GÖKHAN; DOĞUSOY, GÜLEN; ARTAÇ, MEHMET

    2015-01-01

    Hepatocellular carcinoma (HCC) is the fifth most common male-predominant type of cancer worldwide. There is no effective treatment regimen available for advanced-stage disease and chemotherapy is generally ineffective in these patients. The number of studies on the prevalence of K-Ras mutations in HCC patients is currently limited. A total of 58 patients from 6 comprehensive cancer centers in 4 metropolitan cities of Turkey were enrolled in this study. Each center committed to enroll approximately 10 random patients whose formalin-fixed paraffin-embedded tumor tissues were available for K-Ras, exon 2 genotyping. Two methods were applied based on the availability of adequate amounts of tumor DNA. In the first method, the samples were processed using TheraScreen. The genomic DNA was further used to detect the 7 most frequent somatic mutations (35G>A; 35G>C; 35G>T; 34G>A; 34G>C; 34G>T and 38G>A) in codons 12 and 13 in exon 2 of the K-Ras oncogene by quantitative polymerase chain reaction (PCR). In the second method, the genomic DNA was amplified by PCR using primers specific for K-Ras exon 2 with the GML SeqFinder Sequencing System's KRAS kit. The identified DNA sequence alterations were confirmed by sequencing both DNA strands in two independent experiments with forward and reverse primers. A total of 40 samples had adequate tumor tissue for the mutation analysis. A total of 33 (82.5%) of the investigated samples harbored no mutations in exon 2. All the mutations were identified via a direct sequencing technique, whereas none were identified by TheraScreen. In conclusion, in our patients, HCC exhibited a remarkably low (<20%) K-Ras mutation rate. Patients harboring K-Ras wild-type tumors may be good candidates for treatment with epidermal growth factor inhibitors, such as cetuximab. PMID:26807232

  20. p16 and K-ras gene mutations in the intraductal precursors of human pancreatic adenocarcinoma.

    PubMed

    Moskaluk, C A; Hruban, R H; Kern, S E

    1997-06-01

    Pancreatic adenocarcinoma is thought to arise from a noninvasive neoplastic precursor, the pancreatic intraductal lesion (PIL). Mutations of the K-ras gene are known to occur in PILs, but their high prevalence among PILs within the general population probably limit the use of K-ras as a marker of eventual clinical risk. In search of genetic constellations that might indicate the progression of some PILs toward an invasive phenotype, mutations at both the K-ras and p16 genes were sought within PILs of 10 pancreata resected for adenocarcinoma. K-ras mutations were present in most PILs and in nearly all PILs having nuclear atypia. In half of the patients, two or more unique K-ras mutations were identified among distinct PILs, which is evidence for the separate clonal evolution of multiple pancreatic neoplasms within individual patients. p16 alterations (one homozygous deletion and three point mutations) were found in 4 of the 10 carcinomas; these four pancreata harbored p16 alterations in three of nine PILs, of which one was a "histologically early" lesion. Two patients had p16 alterations in PILs matching those of the associated carcinomas. p16 mutations were not found in PILs of pancreata having wild-type p16 in the carcinoma, nor were they found in ducts having normal histology. It is suggested that alterations of the p16 gene affect a subset of PILs that contain mutations of the K-ras gene and that these mutations might identify high-risk precursors of the invasive malignancy. PMID:9187111

  1. Multiple cells-of-origin of mutant K-Ras-induced mouse lung adenocarcinoma.

    PubMed

    Sutherland, Kate D; Song, Ji-Ying; Kwon, Min Chul; Proost, Natalie; Zevenhoven, John; Berns, Anton

    2014-04-01

    Much controversy surrounds the cell-of-origin of mutant K-Ras (K-RasG12D)-induced lung adenocarcinoma. To shed light on this issue, we have used technology that enables us to conditionally target K-RasG12D expression in Surfactant Protein C (SPC)(+) alveolar type 2 cells and in Clara cell antigen 10 (CC10)(+) Clara cells by use of cell-type-restricted recombinant Adeno-Cre viruses. Experiments were performed both in the presence and absence of the tumor suppressor gene p53, enabling us to assess what effect the cell-of-origin and the introduced genetic lesions have on the phenotypic characteristics of the resulting adenocarcinomas. We conclude that both SPC-expressing alveolar type 2 cells and CC10-expressing Clara cells have the ability to initiate malignant transformation following the introduction of these genetic alterations. The lungs of K-Ras(lox-Stop-lox-G12D/+) and K-Ras(lox-Stop-lox-G12D/+);tumor suppressor gene Trp53(F/F) mice infected with Adeno5-SPC-Cre and Adeno5-CC10-Cre viruses displayed differences in their tumor spectrum, indicating distinct cellular routes of tumor initiation. Moreover, using a multicolor Cre reporter line, we demonstrate that the resulting tumors arise from a clonal expansion of switched cells. Taken together, these results indicate that there are multiple cellular paths to K-RasG12D-induced adenocarcinoma and that the initiating cell influences the histopathological phenotype of the tumors that arise. PMID:24586047

  2. Identification of a ternary protein-complex as a therapeutic target for K-Ras-dependent colon cancer

    PubMed Central

    Hou, Songwang; Li, Gang; Yin, Ning; Dong, Lei; Lepp, Adrienne; Chesnik, Marla A.; Mirza, Shama P.; Szabo, Aniko; Tsai, Susan; Basir, Zainab; Wu, Shixiu; Chen, Guan

    2014-01-01

    A cancer phenotype is driven by several proteins and targeting a cluster of functionally interdependent molecules should be more effective for therapeutic intervention. This is specifically important for Ras-dependent cancer, as mutated (MT) Ras is non-druggable and targeting its interaction with effectors may be essential for therapeutic intervention. Here, we report that a protein-complex activated by the Ras effector p38γ MAPK is a novel therapeutic target for K-Ras-dependent colon cancer. Unbiased proteomic screening and immune-precipitation analyses identified p38γ interaction with heat shock protein 90 (Hsp90) and K-Ras in K-Ras MT, but not wild-type (WT), colon cancer cells, indicating a role of this complex in Ras-dependent growth. Further experiments showed that this complex requires p38γ and Hsp90 activity to maintain MT, but not WT, K-Ras protein expression. Additional studies demonstrated that this complex is activated by p38γ-induced Hsp90 phosphorylation at S595, which is important for MT K-Ras stability and for K-Ras dependent growth. Of most important, pharmacologically inhibition of Hsp90 or p38γ activity disrupts the complex, decreases K-Ras expression, and selectively inhibits the growth of K-Ras MT colon cancer in vitro and in vivo. These results demonstrated that the p38γ-activated ternary complex is a novel therapeutic target for K-Ras-dependent colon cancer. PMID:24962213

  3. Implication of K-ras and p53 in colorectal cancer carcinogenesis in Tunisian population cohort.

    PubMed

    Ines, Chaar; Donia, Ounissi; Rahma, Boughriba; Ben Ammar, Azza; Sameh, Amara; Khalfallah, Taher; Abdelmajid, Ben Hmida; Sabeh, Mzabi; Saadia, Bouraoui

    2014-07-01

    According to the multistep route of genetic alterations in the colorectal adenoma-carcinoma sequence, the complex K-ras/p53 mutation is one of the first alterations to occur and represent an important genetic event in colorectal cancer (CRC). An evaluation of the mutation spectra in K-ras and p53 gene was effected in 167 Tunisian patients with sporadic CRC to determine whether our populations have similar pattern of genetic alteration as in Maghrebin's population. Mutation patterns of codon 12-13 of K-ras and exon 5-8 of p53 were analyzed by immunohistochemistry and PCR-SSCP and confirmed by sequencing. Mutations in the K-ras gene were detected in 31.13 % and affect the women more than the men (p = 0.008). Immunostaining showed that expression of p21 ras was correlated with the advanced age (p = 0.004), whereas loss of signal was associated with mucinous histotype (p = 0.003). Kaplan-Meier survival curve found that patients with the K-ras mutation had a shorter survival compared with patients without mutation (p = 0.005). Alteration in p53 was seen in 17.4 % of patients and affects three hot spot codons such as 175, 245, and 248. Overexpression of p53 was seen in 34.1 % and correlated with tumor node metastasis (TNM) advanced stage (p = 0.037) and mucinous histotype (p = 0.001). A high concordance between p53 expression and alteration (p<0.005) was shown. Concomitant mutations in K-ras and p53 gene were detected in only 4 % of tumors. K-ras and p53 undergo separate pathways in colorectal tumorogenesis. Interestingly, mutations in the K-ras gene might be considered a valuable prognostic factor correlated to poor outcome. p53 gene alterations were rather low in our set, and methylation pattern of p53 is required to elucidate the molecular basis of this protein in CRC. PMID:24763823

  4. The anticancer effects of Saccharina japonica on 267B1/K-ras human prostate cancer cells.

    PubMed

    Jo, Mi Jeong; Kim, Hyung Rak; Kim, Gun Do

    2012-11-01

    Saccharina japonica (S. japonica), a brown macro-alga, has been used as a traditional medicine in Korea for thousands of years. In this study, the potential anticancer effects of S. japonica were evaluated on 267B1/K-ras human prostate cancer cells. The exposure of cells to the extract induced inhibition of cell growth by increasing the number of apoptotic cells with cell shrinkage and inhibition of cell cycle progression. The effects of the extract on the cells were assessed by studying the cleavage of caspases and the target proteins of caspases. The increased expression of various cleaved caspases and changed expression of other proteins related in the apoptosis pathway were observed. 4'-6-Diamidino-2-phenylindole (DAPI) and immunofluorescence staining showed the cells undergoing apoptosis. Apoptosis induced changes in the expression of proteins involved in a variety of signaling pathways such as endocellular reticulum (ER) stress, death receptor and mammalian target of rapamycin (mTOR)-FoxO-mediated pathways. The data suggest that the extract (n-hexane sub-fraction) of S. japonica, induces apoptosis and cell cycle arrest in 267B1/K-ras human prostate cancer cells, and has potential as a complementary agent for cancer prevention. PMID:22941421

  5. Zidovudine, abacavir and lamivudine increase the radiosensitivity of human esophageal squamous cancer cell lines.

    PubMed

    Chen, Xuan; Wang, Cong; Guan, Shanghui; Liu, Yuan; Han, Lihui; Cheng, Yufeng

    2016-07-01

    Telomerase is a type of reverse transcriptase that is overexpressed in almost all human tumor cells, but not in normal tissues, which provides an opportunity for radiosensitization targeting telomerase. Zidovudine, abacavir and lamivudine are reverse transcriptase inhibitors that have been applied in clinical practice for several years. We sought to explore the radiosensitization effect of these three drugs on human esophageal cancer cell lines. Eca109 and Eca9706 cells were treated with zidovudine, abacavir and lamivudine for 48 h before irradiation was administered. Samples were collected 1 h after irradiation. Clonal efficiency assay was used to evaluate the effect of the combination of these drugs with radiation doses of 2, 4, 6 and 8 Gy. DNA damage was measured by comet assay. Telomerase activity (TA) and relative telomere length (TL) were detected and evaluated by real-time PCR. Apoptosis rates were assessed by flow cytometric analysis. The results showed that all the drugs tested sensitized the esophageal squamous cell carcinoma (ESCC) cell lines to radiation through an increase in radiation-induced DNA damage and cell apoptosis, deregulation of TA and decreasing the shortened TL caused by radiation. Each of the drugs investigated (zidovudine, abacavir and lamivudine) could be used for sensitizing human esophageal cancer cell lines to radiation. Consequently, the present study supports the potential of these three drugs as therapeutic agents for the radiosensitization of esophageal squamous cell cancer. PMID:27220342

  6. c-K-ras overexpression is characteristic for metastases derived from a methylcholanthrene-induced fibrosarcoma.

    PubMed

    Algarra, I; Perez, M; Serrano, M J; Garrido, F; Gaforio, J J

    We investigated the relationship between the activation of the c-myc and c-K-ras proto-oncogenes and the acquisition of metastatic potential in a methylcholanthrene-induced BALB/c fibrosarcoma. The murine fibrosarcoma GR9 was originally induced in BALB/c mice following exposure to the carcinogenic chemical 3-methylcholanthrene. To induce spontaneous metastasis, we used two tumor cell clones (B9 and G2) known to differ in their metastatic potential, local tumor growth, H-2 class I expression and sensitivity to natural killer (NK) cells. The metastatic nodes were obtained from the lung, liver and kidney. The results showed: (1) amplification of the c-myc proto-oncogene in original tumor clones as well as in all metastatic nodes; (2) mRNA overexpression without amplification of the K-ras proto-oncogene in the metastatic cells, regardless of their anatomical location; (3) no c-K-ras point mutations at codons 12 and 61, and (4) in general, a statistically significantly reduced in vitro sensitivity of metastatic tumor cells to NK cells as compared with the tumor clones used to induce them (p<0.05). These results therefore suggest that overexpressed c-K-ras mRNA is important during tumor progression, perhaps rendering metastatic tumor cells more resistant to lysis by NK cells. PMID:10729771

  7. VEGF neutralizing aerosol therapy in primary pulmonary adenocarcinoma with K-ras activating-mutations.

    PubMed

    Hervé, Virginie; Rabbe, Nathalie; Guilleminault, Laurent; Paul, Flora; Schlick, Laurène; Azzopardi, Nicolas; Duruisseaux, Michael; Fouquenet, Delphine; Montharu, Jérôme; Redini, Françoise; Paintaud, Gilles; Lemarié, Etienne; Cadranel, Jacques; Wislez, Marie; Heuzé-Vourc'h, Nathalie

    2014-01-01

    K-ras mutations promote angiogenesis in lung cancer and contribute to the drug resistance of cancer cells. It is not clear whether K-ras mutated adenocarcinomas are sensitive to anti-angiogenic therapy with monoclonal antibodies (mAbs) that target vascular endothelial growth factor (VEGF). Anti-angiogenic mAbs are usually delivered systemically, but only a small proportion reaches the lung after intravenous injection. We investigated the relevance of a non-invasive pulmonary route for the delivery of anti-VEGF mAbs in the mouse K-ras(LA1) model. We found that pulmonary delivery of these mAbs significantly reduced the number of tumor lesions and inhibited malignant progression. The antitumor effect involves the VEGFR2-dependent inhibition of blood vessel growth, which impairs tumor proliferation. Pharmacokinetic analysis of aerosolized anti-VEGF showed its low rate of passage into the bloodstream, suggesting that this delivery route is associated with reduced systemic side effects. Our findings highlight the value of the aerosol route for administration of anti-angiogenic mAbs in pulmonary adenocarcinoma with K-ras activating-mutations. PMID:25484066

  8. Alterations in the K-ras and p53 genes in rat lung tumors

    SciTech Connect

    Belinsky, S.A.; Swafford, D.S.; Finch, G.L.; Mitchell, C.E.

    1997-06-01

    Activation of the K-ras protooncogene and inactivation of the p53 tumor suppressor gene are events common to many types of human cancers. Molecular epidemiology studies have associated mutational profiles in these genes with specific exposures. The purpose of this paper is to review investigations that have examined the role of the K-ras and p53 genes in lung tumors induced in the F344 rat by mutagenic and nonmutagenic exposures. Mutation profiles within the K-ras and p53 genes, if present in rat lung tumors, would help to define some of the molecular mechanisms underlying cancer induction by various environmental agents. Pulmonary adenocarcinomas or squamous cell carcinomas were induced by tetranitromethane (TNM), 4-methylnitrosamino-1-(3-pyridyl)-1-butanone (NNK), beryllium metal, plutonium-239, X-ray, diesel exhaust, or carbon black. These agents were chosen because the tumors they produced could arise via different types of DNA damage. Mutation of the K-ras gene was determined by approaches that included DNA transfection, direct sequencing, mismatch hybridization, and restriction fragment length polymorphism analysis. The frequency for mutation of the K-ras gene was exposure dependent. The transition mutations formed could have been derived from deamination of cytosine. Alteration in the p53 gene was assessed by immunohistochemical analysis for p53 protein and single-strand conformation polymorphism (SSCP) analysis of exons 4 to 9. None of the 93 adenocarinomas examined was immunoreactive toward the anti-p53 antibody CM1. In contrast, 14 of 71 squamous cell carcinomas exhibited nuclear p53 immunoreactivity with no correlation to type of exposure. However, SSCP analysis only detected mutations in 2 of 14 squamous cell tumors that were immunoreactive, suggesting that protein stabilization did not stem from mutations within the p53 gene. Thus, the p53 gene does not appear to be involved in the genesis of most rat lung tumors. 2 figs., 2 tabs., 48 refs.

  9. The hypervariable region of K-Ras4B is responsible for its specific interactions with Calmodulin

    PubMed Central

    Abraham, Sherwin J.; Nolet, Ryan P.; Calvert, Richard J.; Anderson, Lucy M.; Gaponenko, Vadim

    2009-01-01

    K-Ras4B belongs to the family of p21 Ras GTPases, which play an important role in cell proliferation, survival and motility. The p21 Ras proteins such as K-Ras4B, K-Ras4A, H-Ras, and N-Ras, share 85% sequence homology and activate very similar signaling pathways. Only the C-terminal hypervariable regions differ significantly. A growing body of literature demonstrates that each Ras isoform possesses unique functions in normal physiological processes as well as in pathogenesis. One of the central questions in the field of Ras biology is how these very similar proteins achieve such remarkable specificity in protein-protein interactions that regulate signal transduction pathways. Here we explore specific binding of K-Ras4B to calmodulin. Using NMR techniques and isothermal titration calorimetry we demonstrate that the hypervariable region of K-Ras contributes in a major way to the interaction with calmodulin while the catalytic domain of K-Ras4B provides a way to control the interaction by nucleotide binding. The hypervariable region of K-Ras4B binds specifically to the C-terminal domain of Ca2+-loaded calmodulin with micromolar affinity, while the GTP-γ-S loaded catalytic domain of K-Ras4B may interact with the N-terminal domain of calmodulin. PMID:19583261

  10. Partial knockdown of TRF2 increase radiosensitivity of human mesenchymal stem cells.

    PubMed

    Orun, O; Tiber, P Mega; Serakinci, N

    2016-09-01

    Telomere repeat binding factor TRF2 is a member of shelterin complex with an important role in protecting and stabilizing chromosomal ends. In the present study, we investigated the effect of partial knockdown of TRF2 on radiosensitivity of telomerase immortalized human mesenchymal stem cells (hMSC-telo1), which have a higher radioresistance compared to non telomerized counterpart. Partial knockdown of the protein achieved 15-20% reduction in TRF2 protein levels. The study compared the effect of 2.5Gy radiation in two-four days after irradiation for hMSC-telo1 cells and the cells transfected with siTRF2 and null control vector. Radio-response of the cells were examined using senescence associated β-Gal assay (β-Gal), colony forming assay (CFU) and γ-H2AX phosphorylation. TRF2 deficiency substantially increased radiosensitivity of cells compared to controls in both proliferation and senescence assay (2.4 fold increase in β-Gal, 1.6 fold decrease in CFU). In addition, it increased the γ-H2AX foci as revealed by both immunfluorescence and Western blot analysis. Our data suggests that partial knockdown of TRF2 in hMSC-telo1 cells cause increased γ-H2AX foci which led to fail TRF2 to protect telomeres from radiation thus TRF2 deficiency led to a 1,5-2 fold increase in the radiosensitivity of hMSC-telo1 cells through telomere destabilization. PMID:26598048

  11. K-Ras promotes the non-small lung cancer cells survival by cooperating with sirtuin 1 and p27 under ROS stimulation.

    PubMed

    Cheng, Dezhi; Zhao, Liang; Xu, Yunsheng; Ou, Rongying; Li, Gang; Yang, Han; Li, Wenfeng

    2015-09-01

    Cigarette smoking might lead to lung cancer. However, the related signaling pathways at molecular level remained unknown until now. In this study, we studied the signaling processes associated between tobacco exposure and lung cancer. First, we detected and validated pathway-specific gene expression at bronchial epithelium. These proteins reflected the activation of signaling pathways relevant to tobacco exposure, including ATM, BCL2, GPX1, K-Ras, IKBKB, and SIRT1. Tobacco smoking was simulated via reactive oxygen species (ROS) pathway. ROS not only arrested cell cycle at G1/S stage but also increased expressions of Sirt1 and p27. Further studies showed that the expression of p27 was dependent on ERK1/2 activation, and p27 itself could halt cell cycle by inhibiting the activation of CDKs. Moreover, activation of K-Ras, the key regulator of Ras/ERK pathway, was tightly regulated by enzyme activity of Sirt1. Deacetylation of K-Ras by Sirt1 increased the transformation of Ras-GTP to Ras-GDP, promoting the activation of downstream of ERK1/2. In reverse, Ras/ERK pathway could also regulate Sirt1 transcription. In conclusion, inhibition of Sirt1 may be an effective strategy for the prevention of tumor progression in high-risk patients or as a therapeutic strategy in established tumors. PMID:25894374

  12. Activated K-Ras, But Not H-Ras or N-Ras, Regulates Brain Neural Stem Cell Proliferation in a Raf/Rb-Dependent Manner

    PubMed Central

    Bender, R. Hugh F.; Haigis, Kevin M.; Gutmann, David H.

    2016-01-01

    Neural stem cells (NSCs) give rise to all the major cell types in the brain, including neurons, oligodendrocytes, and astrocytes. However, the intracellular signaling pathways that govern brain NSC proliferation and differentiation have been incompletely characterized to date. Since some neurodevelopmental brain disorders (Costello syndrome and Noonan syndrome) are caused by germline activating mutations in the RAS genes, Ras small GTPases are likely critical regulators of brain NSC function. In the mammalian brain, Ras exists as three distinct molecules (H-Ras, K-Ras, and N-Ras), each with different subcellular localizations, downstream signaling effectors, and biological effects. Leveraging a novel series of conditional-activated Ras molecule-expressing genetically engineered mouse strains, we demonstrate that activated K-Ras, but not H-Ras or N-Ras, expression increases brain NSC growth in a Raf-dependent, but Mek-independent, manner. Moreover, we show that activated K-Ras regulation of brain NSC proliferation requires Raf binding and suppression of retinoblastoma (Rb) function. Collectively, these observations establish tissue-specific differences in activated Ras molecule regulation of brain cell growth that operate through a noncanonical mechanism. PMID:25788415

  13. Epidermal growth factor receptor and K-Ras in non-small cell lung cancer-molecular pathways involved and targeted therapies

    PubMed Central

    de Mello, Ramon Andrade; Marques, Dânia Sofia; Medeiros, Rui; Araújo, António MF

    2011-01-01

    Lung cancer is currently the leading cause of cancer death in Western nations. Non-small cell lung cancer (NSCLC) represents 80% of all lung cancers, and adenocarcinoma is the predominant histological type. Despite the intensive research carried out on this field and therapeutic advances, the overall prognosis of these patients remains unsatisfactory, with a 5-year overall survival rate of less than 15%. Nowadays, pharmacogenetics and pharmacogenomics represent the key to successful treatment. Recent studies suggest the existence of two distinct molecular pathways in the carcinogenesis of lung adenocarcinoma: one associated with smoking and activation of the K-Ras oncogene and the other not associated with smoking and activation of the epidermal growth factor receptor (EGFR). The K-ras mutation is mainly responsible for primary resistance to new molecules which inhibit tyrosine kinase EGFR (erlotinib and gefitinib) and most of the EGFR mutations are responsible for increased tumor sensitivity to these drugs. This article aims to conduct a systematic review of the literature regarding the molecular pathways involving the EGFR, K-Ras and EGFR targeted therapies in NSCLC tumor behavior. PMID:22087435

  14. Slug inhibition increases radiosensitivity of oral squamous cell carcinoma cells by upregulating PUMA.

    PubMed

    Jiang, Fangfang; Zhou, Lijie; Wei, Changbo; Zhao, Wei; Yu, Dongsheng

    2016-08-01

    As a new strategy, radio-gene therapy was widely used for the treatment of cancer patients in recent few years. Slug was involved in the radioresistance of various cancers and has been found to have an anti-apoptotic effect. This study aims to investigate whether the modulation of Slug expression by siRNA affects oral squamous cell carcinoma sensitivity to X-ray irradiation through upregulating PUMA. Two oral squamous cell carcinoma cell lines (HSC3 and HSC6) were transfected with small interfering RNA (siRNA) targeting Slug and subjected to radiotherapy in vitro. After transfection with Slug siRNA, both HSC3 and HSC6 cells showed relatively lower expression of Slug and higher expression of PUMA. The Slug siRNA transfected cells showed decreased survival and proliferation rates, an increased apoptosis rate and enhanced radiosensitivity to X-ray irradiation. Our results revealed that Slug siRNA transfection in combination with radiation increased the expression of PUMA, which contributed to radiosensitivity of oral squamous cell carcinoma cells. Thus, controlling the expression of Slug might contribute to enhance sensitivity of HSC3 and HSC6 cells toward X-ray irradiation in vitro by upregulating PUMA. PMID:27277529

  15. Specific repression of mutant K-RAS by 10-23 DNAzyme: Sensitizing cancer cell to anti-cancer therapies

    SciTech Connect

    Yu, S.-H.; Wang, T.-H.; Au, L.-C.

    2009-01-09

    Point mutations of the Ras family are frequently found in human cancers at a prevalence rate of 30%. The most common mutation K-Ras(G12V), required for tumor proliferation, survival, and metastasis due to its constitutively active GTPase activity, has provided an ideal target for cancer therapy. 10-23 DNAzyme, an oligodeoxyribonucleotide-based ribonuclease consisting of a 15-nucleotide catalytical domain flanked by two target-specific complementary arms, has been shown to effectively cleave the target mRNA at purine-pyrimidine dinucleotide. Taking advantage of this specific property, 10-23 DNAzyme was designed to cleave mRNA of K-Ras(G12V)(GGU {yields} GUU) at the GU dinucleotide while left the wild-type (WT) K-Ras mRNA intact. The K-Ras(G12V)-specific 10-23 DNAzyme was able to reduce K-Ras(G12V) at both mRNA and protein levels in SW480 cell carrying homozygous K-Ras(G12V). No effect was observed on the WT K-Ras in HEK cells. Although K-Ras(G12V)-specific DNAzymes alone did not inhibit proliferation of SW480 or HEK cells, pre-treatment of this DNAzyme sensitized the K-Ras(G12V) mutant cells to anti-cancer agents such as doxorubicin and radiation. These results offer a potential of using allele-specific 10-23 DNAzyme in combination with other cancer therapies to achieve better effectiveness on cancer treatment.

  16. Anti-tumor activity of ESX1 on cancer cells harboring oncogenic K-ras mutation

    SciTech Connect

    Nakajima, Junta; Ishikawa, Susumu; Hamada, Jun-Ichi; Yanagihara, Masatomo; Koike, Takao; Hatakeyama, Masanori

    2008-05-23

    Human ESX1 is a 65-kilodalton (kDa) paired-like homeoprotein that is proteolytically processed into N-terminal 45-kDa and C-terminal 20-kDa fragments. The N-terminal ESX1 fragment, which contains the homeodomain, localizes to the nucleus and represses mRNA transcription from the K-ras gene. When we inoculated human colorectal carcinoma HCT116 constitutive expressing N-terminal region of ESX1 (N-ESX1) into nude mice, transfectant cells uniformly showed decreased tumor-forming activity compared with that of the parental cells. Furthermore, pretreatment of HCT116 carcinoma cells with a fusion protein consisting of N-ESX1 and the protein-transduction domain derived from the human immunodeficiency virus type-1 TAT protein gave rise to a dramatic reduction in the tumorigenicity of HCT116 cells in nude mice. Our results provide first in vivo evidence for the molecular targeting therapeutic application of the K-ras repressor ESX1, especially TAT-mediated transduction of N-ESX1, in the treatment of human cancers having oncogenic K-ras mutations.

  17. Geranylgeranyl Diphosphate Synthase Modulates Fetal Lung Branching Morphogenesis Possibly through Controlling K-Ras Prenylation.

    PubMed

    Jia, Wen-Jun; Jiang, Shan; Tang, Qiao-Li; Shen, Di; Xue, Bin; Ning, Wen; Li, Chao-Jun

    2016-06-01

    G proteins play essential roles in regulating fetal lung development, and any defects in their expression or function (eg, activation or posttranslational modification) can lead to lung developmental malformation. Geranylgeranyl diphosphate synthase (GGPPS) can modulate protein prenylation that is required for protein membrane-anchoring and activation. Here, we report that GGPPS regulates fetal lung branching morphogenesis possibly through controlling K-Ras prenylation during fetal lung development. GGPPS was continuously expressed in lung epithelium throughout whole fetal lung development. Specific deletion of geranylgeranyl diphosphate synthase 1 (Ggps1) in lung epithelium during fetal lung development resulted in neonatal respiratory distress syndrome-like disease. The knockout mice died at postnatal day 1 of respiratory failure, and the lungs showed compensatory pneumonectasis, pulmonary atelectasis, and hyaline membranes. Subsequently, we proved that lung malformations in Ggps1-deficient mice resulted from the failure of fetal lung branching morphogenesis. Further investigation revealed Ggps1 deletion blocked K-Ras geranylgeranylation and extracellular signal-related kinase 1 or 2/mitogen-activated protein kinase signaling, which in turn disturbed fibroblast growth factor 10 regulation on fetal lung branching morphogenesis. Collectively, our data suggest that GGPPS is essential for maintaining fetal lung branching morphogenesis, which is possibly through regulating K-Ras prenylation. PMID:27106761

  18. The K-Ras 4A isoform promotes apoptosis but does not affect either lifespan or spontaneous tumor incidence in aging mice

    SciTech Connect

    Plowman, Sarah J.; Arends, Mark J.; Brownstein, David G.; Luo Feijun; Devenney, Paul S.; Rose, Lorraine; Ritchie, Ann-Marie; Berry, Rachel L.; Harrison, David J.; Hooper, Martin L.; Patek, Charles E. . E-mail: Charles.Patek@ed.ac.uk

    2006-01-01

    Ras proteins function as molecular switches in signal transduction pathways, and, here, we examined the effects of the K-ras4A and 4B splice variants on cell function by comparing wild-type embryonic stem (ES) cells with K-ras {sup tm{delta}}{sup 4A/tm{delta}}{sup 4A} (exon 4A knock-out) ES cells which express K-ras4B only and K-ras {sup -/-} (exons 1-3 knock-out) ES cells which express neither splice variant, and intestinal epithelium from wild-type and K-ras {sup tm{delta}}{sup 4A/tm{delta}}{sup 4A} mice. RT-qPCR analysis found that K-ras4B expression was reduced in K-ras {sup tm{delta}}{sup 4A/tm{delta}}{sup 4A} ES cells but unaffected in small intestine. K-Ras deficiency did not affect ES cell growth, and K-Ras4A deficiency did not affect intestinal epithelial proliferation. K-ras {sup tm{delta}}{sup 4A/tm{delta}}{sup 4A} and K-ras {sup -/-} ES cells showed a reduced capacity for differentiation following LIF withdrawal, and K-ras {sup -/-} cells were least differentiated. K-Ras4A deficiency inhibited etoposide-induced apoptosis in ES cells and intestinal epithelial cells. However, K-ras {sup tm{delta}}{sup 4A/tm{delta}}{sup 4A} ES cells were more resistant to etoposide-induced apoptosis than K-ras {sup -/-} cells. The results indicate that (1) K-Ras4A promotes apoptosis while K-Ras4B inhibits it, and (2) K-Ras4B, and possibly K-Ras4A, promotes differentiation. The findings raise the possibility that alteration of the K-Ras4A/4B isoform ratio modulates tumorigenesis by differentially affecting stem cell survival and/or differentiation. However, K-Ras4A deficiency did not affect life expectancy or spontaneous overall tumor incidence in aging mice.

  19. Increased Chromosomal Radiosensitivity in Women Carrying BRCA1/BRCA2 Mutations Assessed With the G2 Assay

    SciTech Connect

    Ernestos, Beroukas; Nikolaos, Pandis; Koulis, Giannoukakos; Eleni, Rizou; Konstantinos, Beroukas; Alexandra, Giatromanolaki; Michael, Koukourakis

    2010-03-15

    Purpose: Several in vitro studies suggest that BRCA1 and BRCA2 mutation carriers present increased sensitivity to ionizing radiation. Different assays for the assessment of deoxyribonucleic acid double-strand break repair capacity have been used, but results are rather inconsistent. Given the concerns about the possible risks of breast screening with mammography in mutation carrier women and the potentially damaging effects of radiotherapy, the purpose of this study was to further investigate the radiosensitivity of this population. Methods and Materials: The G2 chromosomal radiosensitivity assay was used to assess chromosomal breaks in lymphocyte cultures after exposure to 1 Gy. A group of familiar breast cancer patients carrying a mutation in the BRCA1 or BRCA2 gene (n = 15) and a group of healthy mutation carriers (n = 5) were investigated and compared with a reference group of healthy women carrying no mutation (n = 21). Results: BRCA1 and BRCA2 mutation carriers had a significantly higher number of mean chromatid breaks per cell (p = 0.006) and a higher maximum number of breaks (p = 0.0001) as compared with their matched controls. Both healthy carriers and carriers with a cancer history were more radiosensitive than controls (p = 0.002 and p = 0.025, respectively). Age was not associated with increased radiosensitivity (p = 0.868). Conclusions: Our results indicate that BRCA1 and BRCA2 mutation carriers show enhanced radiosensitivity, presumably because of the involvement of the BRCA genes in deoxyribonucleic acid repair and cell cycle control mechanisms.

  20. Mutations in Succinate Dehydrogenase Subunit C Increase Radiosensitivity and Bystander Responses

    NASA Astrophysics Data System (ADS)

    Zhou, Hongning; Hei, Tom K.

    Although radiation-induced bystander effect is well studied in the past decade, the precise mech-anisms are still unclear. It is likely that a combination of pathways involving both primary and secondary signaling processes is involved in producing a bystander effect. There is recent evidence that mitochondria play a critical role in bystander responses. Recently studies found that a mutation in succinate dehydrogenese subunit C (SDHC), an integral membrane protein in complex II of the electron transport chain, resulted in increased superoxide, oxidative stress, apoptosis, tumorigenesis, and genomic instability, indicating that SDHC play a critical role in maintaining mitochondrial function. In the present study, using Chinese hamster fibroblasts (B1 cells) and the mutants (B9 cells) containing a single base substitution that produced a premature stop codon resulting in a 33-amino acid COOH-terminal truncation of the SDHC protein, we found that B9 cells had an increase in intracellular superoxide content, nitric oxide species, and mitochondrial membrane potential when compared with wild type cells. After irradiated with a grade of doses of gamma rays, B9 cells show an increased radiosensitivity, especially at high doses. The HPRT- mutant yield after gamma-ray irradiation in B9 cells was significantly higher than that of B1 cells. A single, 3Gy dose of gamma-rays increased the background mutant level by more than 4 fold. In contrast, the mutant induction was less than 2 fold in B1 cells. In addition, B9 cells produced a higher bystander mutagenesis after alpha particle irradiation than the B1 cells. Furthermore, pretreated with carboxy-2-phenyl-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide (c-PTIO), a nitric oxide scavenger, significantly decreased the bystander effect. Our findings demonstrate that a mutation in SDHC increases radiosensitivity in both directly irradiated cells and in neighboring bystander cells, and mito-chondrial function play an essential role in

  1. K-ras mutation at codon 12 in stage I pancreatic adenocarcinoma: analysis by laser capture microdissection and direct sequencing.

    PubMed

    Chang, M C; Chang, Y T; Wu, M S; Shun, C T; Tien, Y W; Lin, J T

    2001-05-01

    Pancreatic ductal adenocarcinoma has been reported to carry a rate mutation high in codon 12 of the K-ras oncogene. To avoid the pitfalls of conventional methods of tissue dissection that might affect the sensitivity and specificity of detecting K-ras mutation, laser capture microdissection (LCM) technique was used. Pancreatic adenocarcinoma tissues were obtained from 15 patients who underwent Whipple's procedure. Selected tissues procured by LCM were analyzed by direct sequencing after polymerase chain reaction amplification of K-ras sequences at codon 12. K-ras mutation was noted in nine patients. All mutations showed G to A substitution at codon 12. The mutational pattern (GGT to GAT) is similar in both western and eastern reports. LCM is a feasible method to effectively obtain pure tumor cells from a surgical specimen. It remains to be determined whether this low mutation rate is a result of relatively early stage of disease or different carcinogenesis in different geographic regions. PMID:11432318

  2. Increased betulinic acid induced cytotoxicity and radiosensitivity in glioma cells under hypoxic conditions

    PubMed Central

    2011-01-01

    Background Betulinic acid (BA) is a novel antineoplastic agent under evaluation for tumor therapy. Because of the selective cytotoxic effects of BA in tumor cells (including gliomas), the combination of this agent with conservative therapies (such as radiotherapy and chemotherapy) may be useful. Previously, the combination of BA with irradiation under hypoxic conditions had never been studied. Methods In this study, the effects of 3 to 30 μM BA on cytotoxicity, migration, the protein expression of PARP, survivin and HIF-1α, as well as radiosensitivity under normoxic and hypoxic conditions were analyzed in the human malignant glioma cell lines U251MG and U343MG. Cytotoxicity and radiosensitivity were analyzed with clonogenic survival assays, migration was analyzed with Boyden chamber assays (or scratch assays) and protein expression was examined with Western blot analyses. Results Under normoxic conditions, a half maximal inhibitory concentration (IC50) of 23 μM was observed in U251MG cells and 24 μM was observed in U343MG cells. Under hypoxic conditions, 10 μM or 15 μM of BA showed a significantly increased cytotoxicity in U251MG cells (p = 0.004 and p = 0.01, respectively) and U343MG cells (p < 0.05 and p = 0.01, respectively). The combination of BA with radiotherapy resulted in an additive effect in the U343MG cell line under normoxic and hypoxic conditions. Weak radiation enhancement was observed in U251MG cell line after treatment with BA under normoxic conditions. Furthermore, under hypoxic conditions, the incubation with BA resulted in increased radiation enhancement. The enhancement factor, at an irradiation dose of 15 Gy after treatment with 10 or 15 μM BA, was 2.20 (p = 0.02) and 4.50 (p = 0.03), respectively. Incubation with BA led to decreased cell migration, cleavage of PARP and decreased expression levels of survivin in both cell lines. Additionally, BA treatment resulted in a reduction of HIF-1α protein under hypoxic conditions. Conclusion Our

  3. Activating the Expression of Human K-rasG12D Stimulates Oncogenic Transformation in Transgenic Goat Fetal Fibroblast Cells

    PubMed Central

    Gong, Jianhua; Wang, Zhongde; Polejaeva, Irina; Salgia, Ravi; Kao, Chien-Min; Chen, Chin-Tu; Chen, Guangchun; Chen, Liaohai

    2014-01-01

    Humane use of preclinical large animal cancer models plays a critical role in understanding cancer biology and developing therapeutic treatments. Among the large animal candidates, goats have great potentials as sustainable sources for large animal cancer model development. Goats are easier to handle and cheaper to raise. The genome of the goats has been sequenced recently. It has been known that goats develop skin, adrenal cortex, breast and other types of cancers. Technically, goats are subject to somatic cell nuclear transfer more efficiently and exhibit better viability through the cloning process. Towards the development of a goat cancer model, we created a transgenic goat fetal fibroblast (GFF) cell as the donor cell for SCNT. Human mutated K-ras (hK-rasG12D) was chosen as the transgene, as it is present in 20% of cancers. Both hK-rasG12D and a herpes simplex viral thymidine kinase (HSV1-tk) reporter genes, flanked by a pair of LoxP sites, were knocked in the GFF endogenous K-ras locus through homologous recombination. Following Cre-mediated activation (with a 95% activation efficiency), hK-rasG12D and HSV1-tk were expressed in the transgenic GFF cells, evidently through the presence of corresponding mRNAs, and confirmed by HSV1-tk protein function assay. The hK-rasG12D expressing GFF cells exhibited enhanced proliferation rates and an anchorage-independent growth behavior. They were able to initiate tumor growth in athymic nude mice. In conclusion, after activating hK-rasG12D gene expression, hK-rasG12D transgenic GFF cells were transformed into tumorgenesis cells. Transgenic goats via SCNT using the above-motioned cells as the donor cells have been established. PMID:24594684

  4. Inhibition of PARP-1 by olaparib (AZD2281) increases the radiosensitivity of a lung tumor xenograft.

    PubMed

    Senra, Joana M; Telfer, Brian A; Cherry, Kim E; McCrudden, Cian M; Hirst, David G; O'Connor, Mark J; Wedge, Stephen R; Stratford, Ian J

    2011-10-01

    PARP-1 is a critical enzyme in the repair of DNA strand breaks. Inhibition of PARP-1 increases the effectiveness of radiation in killing tumor cells. However, although the mechanism(s) are well understood for these radiosensitizing effects in vitro, the underlying mechanism(s) in vivo are less clear. Nicotinamide, a drug structurally related to the first generation PARP-1 inhibitor, 3-aminobenzamide, reduces tumor hypoxia by preventing transient cessations in tumor blood flow, thus improving tumor oxygenation and sensitivity to radiotherapy. Here, we investigate whether olaparib, a potent PARP-1 inhibitor, enhances radiotherapy, not only by inhibiting DNA repair but also by changing tumor vascular hemodynamics in non-small cell lung carcinoma (NSCLC). In irradiated Calu-6 and A549 cells, olaparib enhanced the cytotoxic effects of radiation (sensitizer enhancement ratio at 10% survival = 1.5 and 1.3) and DNA double-strand breaks persisted for at least 24 hours after treatment. Combination treatment of Calu-6 xenografts with olaparib and fractionated radiotherapy caused significant tumor regression (P = 0.007) relative to radiotherapy alone. To determine whether this radiosensitization was solely due to effects on DNA repair, we used a dorsal window chamber model to establish the drug/radiation effects on vessel dynamics. Olaparib alone, when given as single or multiple daily doses, or in combination with fractionated radiotherapy, increased the perfusion of tumor blood vessels. Furthermore, an ex vivo assay in phenylephrine preconstricted arteries confirmed olaparib to have higher vasodilatory properties than nicotinamide. This study suggests that olaparib warrants consideration for further development in combination with radiotherapy in clinical oncology settings such as NSCLC. PMID:21825006

  5. Early recognition of lung cancer by integrin targeted imaging in K-ras mouse model.

    PubMed

    Ermolayev, Vladimir; Mohajerani, Pouyan; Ale, Angelique; Sarantopoulos, Athanasios; Aichler, Michaela; Kayser, Gian; Walch, Axel; Ntziachristos, Vasilis

    2015-09-01

    Non-small cell lung cancer is characterized by slow progression and high heterogeneity of tumors. Integrins play an important role in lung cancer development and metastasis and were suggested as a tumor marker; however their role in anticancer therapy remains controversial. In this work, we demonstrate the potential of integrin-targeted imaging to recognize early lesions in transgenic mouse model of lung cancer based on spontaneous introduction of mutated human gene bearing K-ras mutation. We conducted ex vivo and fluorescence molecular tomography-X-ray computed tomography (FMT-XCT) in vivo imaging and analysis for specific targeting of early lung lesions and tumors in rodent preclinical model for lung cancer. The lesions and tumors were characterized by histology, immunofluorescence and immunohistochemistry using a panel of cancer markers. Ex vivo, the integrin-targeted fluorescent signal significantly differed between wild type lung tissue and K-ras pulmonary lesions (PL) at all ages studied. The panel of immunofluorescence experiments demonstrated that PL, which only partially show cancer cell features were detected by αvβ3-integrin targeted imaging. Human patient material analysis confirmed the specificity of target localization in different lung cancer types. Most importantly, small tumors in the lungs of 4-week-old animals could be noninvasively detected in vivo on the fluorescence channel of FMT-XCT. Our findings demonstrated αvβ3-integrin targeted fluorescent imaging to specifically detect premalignant pleural lesions in K-ras mice. Integrin targeted imaging may find application areas in preclinical research and clinical practice, such as early lung cancer diagnostics, intraoperative assistance or therapy monitoring. PMID:25450481

  6. Tissue-specific hypomethylation of the human c-K-ras gene.

    PubMed Central

    Metter, J; Cho, C

    1989-01-01

    Methylation of the c-K-ras gene was examined in a wide variety of human tissues using the methylation sensitive restriction endonuclease HpaII. All tissues showed hypomethylation in the region of exon zero. Specific hypomethylation of a particular HpaII site in the second intron was observed in gastrointestinal and tracheobronchial epithelial cell DNAs. Specific hypomethylation was also observed in a cluster of HpaII sites within the first intron in sperm, endometrium and placenta DNAs. These regions were predominantly methylated in a wide variety of other tissues, including fetal gut. The possible implications are discussed. Images PMID:2476726

  7. The role of antiangiogenic agents in the treatment of patients with advanced colorectal cancer according to K-RAS status.

    PubMed

    García-Alfonso, Pilar; Grande, Enrique; Polo, Eduardo; Afonso, Ruth; Reina, Juan José; Jorge, Mónica; Campos, Juan Manuel; Martínez, Virginia; Angeles, Cristina; Montagut, Clara

    2014-10-01

    Colorectal cancer (CRC) is the fourth most commonly diagnosed cancer worldwide. Recently, it has been found that about 40 % of patients with CRC have mutations in the K-RAS gene. Several clinical trials have showed that patients with metastatic colorectal cancer (mCRC) who present tumour-promoting mutations in signalling pathways involving the epidermal growth factor receptor (EGFR), which includes activating K-RAS mutations, do not respond to anti-EGFR drugs such as panitumumab and cetuximab. Hence, K-RAS status is now considered an important negative predictive factor for response to anti-EGFR drugs. Moreover, K-RAS status seems to have also a prognostic role in CRC, but this fact is somewhat controversial. Activity of antiangiogenic agents seems not to be influenced by K-RAS gene status. Tumour angiogenesis has attracted interest in attempts to improve the management of mCRC. The vascular endothelial growth factor (VEGF) pathway is fundamental to the regulation of angiogenesis, and research has focused on developing agents that selectively target it. In this way, the anti-VEGF antibody bevacizumab in combination with chemotherapy has provided important clinical benefits in terms of response rate, progression-free survival and overall survival to patients with mCRC. Efficacy data of bevacizumab in K-RAS wild-type patients seem to be comparable with the efficacy data observed with anti-EGFR therapies in a cross-trial comparison. Although there is a lack of prospective and randomized data in this setting, the combination of chemotherapy plus antiangiogenic agents could be considered as an effective alternative for the treatment of mCRC with independence of K-RAS gene status. Here, we review the available data we have in the literature of the use of antiangiogenic strategies in the treatment of mCRC nowadays. PMID:24793846

  8. Increased radiosensitivity of HPV-positive head and neck cancers: Molecular basis and therapeutic perspectives.

    PubMed

    Mirghani, Haïtham; Amen, Furrat; Tao, Yungan; Deutsch, Eric; Levy, Antonin

    2015-12-01

    Human papillomavirus driven head and neck squamous cell carcinoma (HNSCC), particularly oropharyngeal squamous cell carcinoma (OPSCC), are characterized by a significant survival advantage over their HPV-negative counterparts. Although the reasons behind this are still not fully elucidated, it is widely accepted that these tumors have a higher response to ionizing radiation that might explain their favorable outcomes. Potential underlying intrinsic mechanisms include impaired DNA repair abilities, differences in activated repopulation-signaling pathways and cell cycle control mechanisms. The role of the microenvironment is increasingly highlighted, particularly tumor oxygenation and the immune response. Recent studies have shown a distinct pattern of intratumoral immune cell infiltrates, according to HPV status, and have suggested that an increased cytotoxic T-cell based antitumor immune response is involved in improved prognosis of patients with HPV-positive OPSCC. These significant milestones, in the understanding of HPV-induced HNSCC, pave the way to new therapeutic opportunities. This article reviews the current evidence on the biological basis of increased radiosensitivity in HPV-positive HNSCC and discusses potential therapeutic implications. PMID:26476574

  9. Downregulation of high mobility group box 1 modulates telomere homeostasis and increases the radiosensitivity of human breast cancer cells.

    PubMed

    Ke, Shaobo; Zhou, Fuxiang; Yang, Hui; Wei, Yuehua; Gong, Jun; Mei, Zijie; Wu, Lin; Yu, Haijun; Zhou, Yunfeng

    2015-03-01

    The functions of the high mobility group box 1 (HMGB1) in tumor cells include replenishing telomeric DNA and maintaining cell immortality. There is a negative correlation between human telomerase reverse transcriptase (hTERT) and radiosensitivity in tumor cells. Our aim was to elucidate the relationship among HMGB1, telomere homeostasis and radiosensitivity in MCF-7 cells. In this study, we established stably transfected control (MCF-7-NC) and HMGB1 knockdown (MCF-7-shHMGB1) cell lines. The expression of HMGB1 mRNA and the relative telomere length were examined by real-time PCR. Radiosensitivity was detected by clonogenic assay. The protein expressions were determined by western blot analysis. The telomerase activity was detected by PCR-ELISA. Proliferation ability was examined by CCK-8 assay. Cell cycle and apoptosis were examined by flow cytometry. DNA damage foci were detected by immunofluorescence. ShRNA-mediated downregulation of HMGB1 expression increased the radiosensitivity of MCF-7 cells, and reduced the accumulation of hTERT and cyclin D1. Moreover, knockdown of HMGB1 in MCF-7 cells inhibited telomerase activity and cell proliferation, while increasing the extent of apoptosis. Downregulation of HMGB1 modulated telomere homeostasis by changing the level of telomere-binding proteins, such as TPP1 (PTOP), TRF1 and TRF2. This downregulation also inhibited the ATM and ATR signaling pathways. The current data demonstrate that knockdown of HMGB1 breaks telomere homeostasis, enhances radiosensitivity, and suppresses the repair of DNA damage in human breast cancer cells. These results suggested that HMGB1 might be a potential radiotherapy target in human breast cancer. PMID:25501936

  10. The Structural Basis of Oncogenic Mutations G12, G13 and Q61 in Small GTPase K-Ras4B

    PubMed Central

    Lu, Shaoyong; Jang, Hyunbum; Nussinov, Ruth; Zhang, Jian

    2016-01-01

    Ras mediates cell proliferation, survival and differentiation. Mutations in K-Ras4B are predominant at residues G12, G13 and Q61. Even though all impair GAP-assisted GTP → GDP hydrolysis, the mutation frequencies of K-Ras4B in human cancers vary. Here we aim to figure out their mechanisms and differential oncogenicity. In total, we performed 6.4 μs molecular dynamics simulations on the wild-type K-Ras4B (K-Ras4BWT-GTP/GDP) catalytic domain, the K-Ras4BWT-GTP–GAP complex, and the mutants (K-Ras4BG12C/G12D/G12V-GTP/GDP, K-Ras4BG13D-GTP/GDP, K-Ras4BQ61H-GTP/GDP) and their complexes with GAP. In addition, we simulated ‘exchanged’ nucleotide states. These comprehensive simulations reveal that in solution K-Ras4BWT-GTP exists in two, active and inactive, conformations. Oncogenic mutations differentially elicit an inactive-to-active conformational transition in K-Ras4B-GTP; in K-Ras4BG12C/G12D-GDP they expose the bound nucleotide which facilitates the GDP-to-GTP exchange. These mechanisms may help elucidate the differential mutational statistics in K-Ras4B-driven cancers. Exchanged nucleotide simulations reveal that the conformational transition is more accessible in the GTP-to-GDP than in the GDP-to-GTP exchange. Importantly, GAP not only donates its R789 arginine finger, but stabilizes the catalytically-competent conformation and pre-organizes catalytic residue Q61; mutations disturb the R789/Q61 organization, impairing GAP-mediated GTP hydrolysis. Together, our simulations help provide a mechanistic explanation of key mutational events in one of the most oncogenic proteins in cancer. PMID:26902995

  11. The Bisphenol A analogue Bisphenol S binds to K-Ras4B--implications for 'BPA-free' plastics.

    PubMed

    Schöpel, Miriam; Herrmann, Christian; Scherkenbeck, Jürgen; Stoll, Raphael

    2016-02-01

    K-Ras4B is a small GTPase that belongs to the Ras superfamily of guanine nucleotide-binding proteins. GTPases function as molecular switches in cells and are key players in intracellular signalling. Ras has been identified as an oncogene and is mutated in more than 20% of human cancers. Here, we report that Bisphenol S binds into a binding pocket of K-Ras4B previously identified for various low molecular weight compounds. Our results advocate for more comprehensive safety studies on the toxicity of Bisphenol S, as it is frequently used for Bisphenol A-free food containers. PMID:26867649

  12. Is Increased Low-dose somatic Radiosensitivity Associated with Increased Transgenerational Germline Mutation

    SciTech Connect

    Brenner, David J.

    2008-10-02

    Using single-molecule polymerase chain reaction, the frequency of spontaneous and radiation-induced mutation at an expanded simple tandem repeat (ESTR) locus was studied in DNA samples extracted from sperm and bone marrow of Atm knockout (Atm+/–) heterozygous male mice. The frequency of spontaneous mutation in sperm and bone marrow in Atm+/– males did not significantly differ from that in wild-type BALB/c mice. Acute gamma-ray exposure did not affect ESTR mutation frequency in bone marrow and resulted in similar increases in sperm samples taken from Atm+/– and BALB/c males. Taken together, these results suggest that the Atm haploinsufficiency analyzed in our study does not affect spontaneous and radiation-induced ESTR mutation frequency in mice.

  13. The cell of origin and subtype of K-Ras-induced lung tumors are modified by Notch and Sox2

    PubMed Central

    Xu, Xia; Huang, Lingling; Futtner, Christopher; Schwab, Brian; Rampersad, Rishi R.; Lu, Yun; Sporn, Thomas A.; Hogan, Brigid L.M.

    2014-01-01

    Cell type-specific conditional activation of oncogenic K-Ras is a powerful tool for investigating the cell of origin of adenocarcinomas in the mouse lung. Our previous studies showed that K-Ras activation with a CC10(Scgb1a1)-CreER driver leads to adenocarcinoma in a subset of alveolar type II cells and hyperplasia in the bronchioalveolar duct region. However, no tumors develop in the bronchioles, although recombination occurs throughout this region. To explore underlying mechanisms, we simultaneously modulated either Notch signaling or Sox2 levels in the CC10+ cells along with activation of K-Ras. Inhibition of Notch strongly inhibits adenocarcinoma formation but promotes squamous hyperplasia in the alveoli. In contrast, activation of Notch leads to widespread Sox2+, Sox9+, and CC10+ papillary adenocarcinomas throughout the bronchioles. Chromatin immunoprecipitation demonstrates Sox2 binding to NOTCH1 and NOTCH2 regulatory regions. In transgenic mouse models, overexpression of Sox2 leads to a significant reduction of Notch1 and Notch2 transcripts, while a 50% reduction in Sox2 leads to widespread papillary adenocarcinoma in the bronchioles. Taken together, our data demonstrate that the cell of origin of K-Ras-induced tumors in the lung depends on levels of Sox2 expression affecting Notch signaling. In addition, the subtype of tumors arising from type II cells is determined in part by Notch activation or suppression. PMID:25184679

  14. Immunophenotype and K-RAS mutation in mucinous ovarian adenocarcinoma with mural nodule of high-grade sarcoma: case report.

    PubMed

    Desouki, Mohamed M; Fadare, Oluwole; Kanbour, Anisa; Kanbour-Shakir, Amal

    2014-03-01

    Ovarian mucinous tumors with mural nodules are rare. The mural nodules are microscopically divergent neoplasms of varying sizes that may be benign (eg, sarcoma-like and carcinosarcoma-like), or malignant (eg, anaplastic carcinoma and sarcoma). The K-RAS gene mutation in ovarian mucinous neoplasms with mural nodules has not been previously reported. This is a case report of a 25-year-old female diagnosed with ovarian invasive mucinous adenocarcinoma with mural nodule of high-grade sarcoma. The mucinous tumor component demonstrated a K-RAS codon 12/13 mutation (p.G12V, c.35 G>T), whereas the sarcomatous component demonstrated a K-RAS codon 12/13 mutation (p.G12D, c.35 G>A). Although both tumor components revealed a mutation in codon 12 of K-RAS, they were of different nucleotide substitutions, indicating that these 2 tumor components were of different clonal origins. However, the fact that the 2 mutations identified in the tumor components are the most common mutations reported in mucinous tumors of the ovary, raises the possibility that sarcomatous mural nodules simply represent a form of dedifferentiation in mucinous tumors. PMID:24487474

  15. Translation-dependent mechanisms lead to PML upregulation and mediate oncogenic K-RAS-induced cellular senescence

    PubMed Central

    Scaglioni, Pier Paolo; Rabellino, Andrea; Yung, Thomas M; Bernardi, Rosa; Choi, Sooyeon; Konstantinidou, Georgia; Nardella, Caterina; Cheng, Ke; Pandolfi, Pier Paolo

    2012-01-01

    Expression of oncogenic K-RAS in primary cells elicits oncogene-induced cellular senescence (OIS), a form of growth arrest that potently opposes tumourigenesis. This effect has been largely attributed to transcriptional mechanisms that depend on the p53 tumour suppressor protein. The PML tumour suppressor was initially identified as a component of the PML-RARα oncoprotein of acute promyelocytic leukaemia (APL). PML, a critical OIS mediator, is upregulated by oncogenic K-RAS in vivo and in vitro. We demonstrate here that oncogenic K-RAS induces PML protein upregulation by activating the RAS/MEK1/mTOR/eIF4E pathway even in the absence of p53. Under these circumstances, PML mRNA is selectively associated to polysomes. Importantly, we find that the PML 5′ untranslated mRNA region plays a key role in mediating PML protein upregulation and that its presence is essential for an efficient OIS response. These findings demonstrate that upregulation of PML translation plays a central role in oncogenic K-RAS-induced OIS. Thus, selective translation initiation plays a critical role in tumour suppression with important therapeutic implications for the treatment of solid tumours and APL. PMID:22359342

  16. miR-181a shows tumor suppressive effect against oral squamous cell carcinoma cells by downregulating K-ras

    SciTech Connect

    Shin, Ki-Hyuk; Bae, Susan D.; Hong, Hannah S.; Kim, Reuben H.; Kang, Mo K.; Park, No-Hee

    2011-01-28

    Research highlights: {yields} MicroRNA-181a (miR-181a) was frequently downregulated in oral squamous cell carcinoma (OSCC). {yields} Overexpression of miR-181a suppressed OSCC growth. {yields} K-ras is a novel target of miR-181a. {yields} Decreased miR-181a expression is attributed to its lower promoter activity in OSCC. -- Abstract: MicroRNAs (miRNAs) are epigenetic regulators of gene expression, and their deregulation plays an important role in human cancer, including oral squamous cell carcinoma (OSCC). Recently, we found that miRNA-181a (miR-181a) was upregulated during replicative senescence of normal human oral keratinocytes. Since senescence is considered as a tumor suppressive mechanism, we thus investigated the expression and biological role of miR-181a in OSCC. We found that miR-181a was frequently downregulated in OSCC. Ectopic expression of miR-181a suppressed proliferation and anchorage independent growth ability of OSCC. Moreover, miR-181a dramatically reduces the growth of OSCC on three dimensional organotypic raft culture. We also identified K-ras as a novel target of miR-181a. miR-181a decreased K-ras protein level as well as the luciferase activity of reporter vectors containing the 3'-untranslated region of K-ras gene. Finally, we defined a minimal regulatory region of miR-181a and found a positive correlation between its promoter activity and the level of miR-181a expression. In conclusion, miR-181a may function as an OSCC suppressor by targeting on K-ras oncogene. Thus, miR-181a should be considered for therapeutic application for OSCC.

  17. Detection of K-ras Mutations in Predicting Efficacy of Epidermal Growth Factor Receptor Tyrosine Kinase (EGFR-TK) Inhibitor in Patients with Metastatic Colorectal Cancer

    PubMed Central

    Li, Ze; Liu, Xue-Wei; Chi, Zhao-Cheng; Sun, Bao-Sheng; Cheng, Ying; Cheng, Long-Wei

    2015-01-01

    Epidermal growth factor receptor tyrosine kinase (EGFR-TK) inhibitors are useful in treating different advanced human cancers; however, their clinical efficacy varies. This study detected K-ras mutations to predict the efficacy of EGFR-TK inhibitor cetuximab treatment on Chinese patients with metastatic colorectal cancer (mCRC). A total of 87 patients with metastatic colorectal cancer were treated with cetuximab for 2-16 months, in combination with chemotherapy between August 2008 and July 2012, and tissue samples were used to detect K-ras mutations. The data showed that K-ras mutation occurred in 27/87 (31%). The objective response rates and disease control rate in K-ras wild type and mutant patients were 42% (25/60) versus 11% (3/27) (p<0.05) and 60% (36/60) versus 26% (7/27) (p<0.05), respectively. Patients with the wild-type K-ras had significantly higher median survival times and progression-free survival, than patients with mutated K-ras (21 months versus 17 months, p=0.017; 10 months versus 6 months, p=0.6). These findings suggest that a high frequency of K-ras mutations occurs in Chinese mCRC patients and that K-ras mutation is required to select patients for eligibility for cetuximab therapy. Further prospective studies using a large sample size are needed to confirm these preliminary findings. PMID:25950441

  18. Novel chemical enhancers of heat shock increase thermal radiosensitization through a mitotic catastrophe pathway.

    PubMed

    Sekhar, Konjeti R; Sonar, Vijayakumar N; Muthusamy, Venkatraj; Sasi, Soumya; Laszlo, Andrei; Sawani, Jamil; Horikoshi, Nobuo; Higashikubo, Ryuji; Bristow, Robert G; Borrelli, Michael J; Crooks, Peter A; Lepock, James R; Roti Roti, Joseph L; Freeman, Michael L

    2007-01-15

    Radiation therapy combined with adjuvant hyperthermia has the potential to provide outstanding local-regional control for refractory disease. However, achieving therapeutic thermal dose can be problematic. In the current investigation, we used a chemistry-driven approach with the goal of designing and synthesizing novel small molecules that could function as thermal radiosensitizers. (Z)-(+/-)-2-(1-Benzenesulfonylindol-3-ylmethylene)-1-azabicyclo[2.2.2]octan-3-ol was identified as a compound that could lower the threshold for Hsf1 activation and thermal sensitivity. Enhanced thermal sensitivity was associated with significant thermal radiosensitization. We established the structural requirements for activity: the presence of an N-benzenesulfonylindole or N-benzylindole moiety linked at the indolic 3-position to a 2-(1-azabicyclo[2.2.2]octan-3-ol) or 2-(1-azabicyclo[2.2.2]octan-3-one) moiety. These small molecules functioned by exploiting the underlying biophysical events responsible for thermal sensitization. Thermal radiosensitization was characterized biochemically and found to include loss of mitochondrial membrane potential, followed by mitotic catastrophe. These studies identified a novel series of small molecules that represent a promising tool for the treatment of recurrent tumors by ionizing radiation. PMID:17234780

  19. The combination of tetraiodothyroacetic acid and cetuximab inhibits cell proliferation in colorectal cancers with different K-ras status.

    PubMed

    Lee, Yee-Shin; Chin, Yu-Tang; Yang, Yu-Chen S H; Wei, Po-Li; Wu, Han-Chung; Shih, Ai; Lu, Yueh-Tong; Pedersen, Jens Z; Incerpi, Sandra; Liu, Leroy F; Lin, Hung-Yun; Davis, Paul J

    2016-07-01

    Thyroid hormone induces cancer cell proliferation through its cell surface receptor integrin αvβ3. Acting via integrin αvβ3, the deaminated T4 analog tetraiodothyroacetic acid (tetrac), and its nanoparticle formulation nano-diamino-tetrac (NDAT) could inhibit cell proliferation and xenograft growth. In this study, we investigated the T4 effects on proliferation in colorectal cancer cell lines based on the proliferation marker expressions at both mRNA and protein levels. The effects of tetrac/NDAT, the monoclonal anti-EGFR antibody cetuximab, and their combinations on colorectal cancer cell proliferation were examined according to the relevant gene expression profiles and cell count analysis. The results showed that T4 significantly enhanced PCNA, Cyclin D1 and c-Myc levels in both K-ras wild type HT-29 and mutant HCT 116 cells. In HCT 116 cells, the combination of NDAT and cetuximab significantly suppressed the mRNA expressions of proliferative genes PCNA, Cyclin D1, c-Myc and RRM2 raised by T4 compared to cetuximab alone. In addition, T4-suppressed mRNA expressions of pro-apoptotic genes p53 and RRM2B could be significantly elevated by the combination of NDAT and cetuximab compared to cetuximab alone. In the K-ras mutant HCT 116 cells, but not in the K-ras wild type COLO 205 cells, the combinations of tetrac/NDAT and cetuximab significantly reduced cell proliferation compared to cetuximab alone. In conclusion, T4 promoted colorectal cancer cell proliferation which could be repressed by tetrac and NDAT. The combinations of tetrac/NDAT and cetuximab potentiated cetuximab actions in K-ras mutant colorectal cancer cells. PMID:26980146

  20. Frequency and spectrum of mutations at codons 12 and 13 of the C-K-ras gene in human tumors

    SciTech Connect

    Capella, G.; Cronauer-Mitra, S.; Peinado, M.A.; Perucho, M. )

    1991-06-01

    The frequency of point mutations at codons 12 and 13 of the c-K-ras gene has been determined in a panel of more than 400 human tumors. Mutant c-K-ras genes were detected in about 75% of adenocarcinomas of the pancreas; 40% of adenomas and carcinomas of the colon and rectum; 30% of carcinomas of the bile duct; 25% of carcinomas of the lung, and in lower frequency in other carcinomas, including liver, stomach, and kidney. No mutations were found in carcinomas of the breast, prostate, esophagus, and gall bladder, among others. Comparative analysis of the spectrum of mutations show that while G to A transitions were the most frequent mutations in pancreatic and colo-rectal tumors, G to T transversions were more prevalent in lung carcinomas. The aspartic acid mutation at codon 13 (GGC {r arrow} GAC) was relatively frequent in colo-rectal tumors but rare in pancreatic and lung carcinomas. The differences in the mutation spectrum of the c-K-ras gene in cancers of the gastrointestinal and respiratory tracts are suggestive of differential exposure to genotoxic agents.

  1. K-Ras and cyclooxygenase-2 coactivation augments intraductal papillary mucinous neoplasm and Notch1 mimicking human pancreas lesions

    PubMed Central

    Chiblak, Sara; Steinbauer, Brigitte; Pohl-Arnold, Andrea; Kucher, Dagmar; Abdollahi, Amir; Schwager, Christian; Höft, Birgit; Esposito, Irene; Müller-Decker, Karin

    2016-01-01

    Mutational activation of K-Ras is an initiating event of pancreatic ductal adenocarcinomas (PDAC) that may develop either from pancreatic intraepithelial neoplasia (PanIN) or intraductal papillary mucinous neoplasms (IPMN). Cyclooxygenase-2 (COX-2)-derived prostaglandin E2 (PGE2) is causally related to pancreatic carcinogenesis. Here, we deciphered the impact of COX-2, a key modulator of inflammation, in concert with active mutant K-RasG12D on tumor burden and gene expression signature using compound mutant mouse lines. Concomitant activation of COX-2 and K-RasG12D accelerated the progression of pancreatic intraepithelial lesions predominantly with a cystic papillary phenotype resembling human IPMN. Transcriptomes derived from laser capture microdissected preneoplastic lesions of single and compound mutants revealed a signature that was significantly enriched in Notch1 signaling components. In vitro, Notch1 signaling was COX-2-dependent. In line with these findings, human IPMN stratified into intestinal, gastric and pancreatobillary types displayed Notch1 immunosignals with high prevalence, especially in the gastric lesions. In conclusion, a yet unknown link between activated Ras, protumorigenic COX-2 and Notch1 in IPMN onset was unraveled. PMID:27381829

  2. K-Ras and cyclooxygenase-2 coactivation augments intraductal papillary mucinous neoplasm and Notch1 mimicking human pancreas lesions.

    PubMed

    Chiblak, Sara; Steinbauer, Brigitte; Pohl-Arnold, Andrea; Kucher, Dagmar; Abdollahi, Amir; Schwager, Christian; Höft, Birgit; Esposito, Irene; Müller-Decker, Karin

    2016-01-01

    Mutational activation of K-Ras is an initiating event of pancreatic ductal adenocarcinomas (PDAC) that may develop either from pancreatic intraepithelial neoplasia (PanIN) or intraductal papillary mucinous neoplasms (IPMN). Cyclooxygenase-2 (COX-2)-derived prostaglandin E2 (PGE2) is causally related to pancreatic carcinogenesis. Here, we deciphered the impact of COX-2, a key modulator of inflammation, in concert with active mutant K-Ras(G12D) on tumor burden and gene expression signature using compound mutant mouse lines. Concomitant activation of COX-2 and K-Ras(G12D) accelerated the progression of pancreatic intraepithelial lesions predominantly with a cystic papillary phenotype resembling human IPMN. Transcriptomes derived from laser capture microdissected preneoplastic lesions of single and compound mutants revealed a signature that was significantly enriched in Notch1 signaling components. In vitro, Notch1 signaling was COX-2-dependent. In line with these findings, human IPMN stratified into intestinal, gastric and pancreatobillary types displayed Notch1 immunosignals with high prevalence, especially in the gastric lesions. In conclusion, a yet unknown link between activated Ras, protumorigenic COX-2 and Notch1 in IPMN onset was unraveled. PMID:27381829

  3. The Structural Basis of Oncogenic Mutations G12, G13 and Q61 in Small GTPase K-Ras4B.

    PubMed

    Lu, Shaoyong; Jang, Hyunbum; Nussinov, Ruth; Zhang, Jian

    2016-01-01

    Ras mediates cell proliferation, survival and differentiation. Mutations in K-Ras4B are predominant at residues G12, G13 and Q61. Even though all impair GAP-assisted GTP → GDP hydrolysis, the mutation frequencies of K-Ras4B in human cancers vary. Here we aim to figure out their mechanisms and differential oncogenicity. In total, we performed 6.4 μs molecular dynamics simulations on the wild-type K-Ras4B (K-Ras4B(WT)-GTP/GDP) catalytic domain, the K-Ras4B(WT)-GTP-GAP complex, and the mutants (K-Ras4B(G12C/G12D/G12V)-GTP/GDP, K-Ras4B(G13D)-GTP/GDP, K-Ras4B(Q61H)-GTP/GDP) and their complexes with GAP. In addition, we simulated 'exchanged' nucleotide states. These comprehensive simulations reveal that in solution K-Ras4B(WT)-GTP exists in two, active and inactive, conformations. Oncogenic mutations differentially elicit an inactive-to-active conformational transition in K-Ras4B-GTP; in K-Ras4B(G12C/G12D)-GDP they expose the bound nucleotide which facilitates the GDP-to-GTP exchange. These mechanisms may help elucidate the differential mutational statistics in K-Ras4B-driven cancers. Exchanged nucleotide simulations reveal that the conformational transition is more accessible in the GTP-to-GDP than in the GDP-to-GTP exchange. Importantly, GAP not only donates its R789 arginine finger, but stabilizes the catalytically-competent conformation and pre-organizes catalytic residue Q61; mutations disturb the R789/Q61 organization, impairing GAP-mediated GTP hydrolysis. Together, our simulations help provide a mechanistic explanation of key mutational events in one of the most oncogenic proteins in cancer. PMID:26902995

  4. K-Ras mutation detection in liquid biopsy and tumor tissue as prognostic biomarker in patients with pancreatic cancer: a systematic review with meta-analysis.

    PubMed

    Li, Tao; Zheng, Yuanting; Sun, Hong; Zhuang, Rongyuan; Liu, Jing; Liu, Tianshu; Cai, Weimin

    2016-07-01

    K-Ras gene mutations have been found in most pancreatic cancers; however, conflicting data on the prognostic value of K-Ras mutations in pancreatic cancer have been published. We conducted a meta-analysis to assess its prognostic significance. Literature searches of PubMed, EMBASE, Cochrane Library, Web of Science and Google Scholar were performed through December 2015 to identify publications exploring the association of K-Ras mutation with overall survival. Forty eligible studies involving 3427 patients with pancreatic cancer were included in the present meta-analysis. Our analysis showed a hazard ratio (HR) of negative association with survival of 1.61 [95 % confidence interval (CI) 1.36-1.90; p < 0.01] in K-Ras mutant pancreatic cancer patients. In subgroup analyses, K-Ras mutations detected in tumor tissues and in liquid biopsies had HRs of 1.37 (95 % CI 1.20-1.57; p < 0.01) and 3.16 (95 % CI 2.1-4.71; p < 0.01), respectively. In addition, the HR was higher when K-Ras mutations were detected in fresh frozen samples (HR = 2.01, 95 % CI 1.28-3.16, p = 0.002) than in formalin-fixed, paraffin-embedded (FFPE) samples (HR = 1.29, 95 % CI 1.12-1.49, p < 0.01). Though K-Ras alterations are more frequent among non-East Asian individuals than East Asian individuals, there were no significant differences in HRs of survival between the two ethnic subgroups. In conclusion, this meta-analysis suggests that K-Ras mutations are associated with a worse overall survival in pancreatic cancer patients, especially when mutations are detected in liquid biopsies or fresh frozen tumor tissue samples. PMID:27225938

  5. Increased radiosensitivity of a subpopulation of T-lymphocyte progenitors from patients with Fanconi's anemia

    SciTech Connect

    Knox, S.J.; Wilson, F.D.; Greenberg, B.R.; Shifrine, M.; Rosenblatt, L.S.; Reeves, J.D.; Misra, H.

    1981-06-01

    In vitro radiation survival of peripheral blood T lymphocytes was studied in 15 clinically normal adults and 4 patients with Fanconi's anemia. Tritiated thymidine incorporation in a whole blood lymphocyte stimulation test (LST) and a newly developed whole blood T-lymphocyte colony assay were used to measure lymphocyte blastogenesis and colony formation in response to phytohemagglutinin (PHA) or concanavalin-A (Con-A) stimulation. Lymphocyte colony formation was found to be consistently more sensitive than the LST for detection of low-level radiation effects using both normal cells and lymphocytes from Fanconi's anemia patients. Lymphocytes from patients with Fanconi's anemia were significantly more sensitive to in vitro x irradiation than lymphocytes from clinically normal individuals as measured by their ability to divide when stimulated by PHA in the LST and colony formation assay. No significant difference in the radiosensitivity of the Con-A response was observed between the two groups. The PHA-responsive T-lymphocyte subpopulation in Fanconi's anemia patients appears to be intrinsically defective. The nature of this defect, significance in the disease process, and relevancy of these findings to the establishment of radiation protection standards are discussed.

  6. Increased radiosensitivity of a subpopulation ot T-lymphocyte progenitors from patients with Fanconi's anemia

    SciTech Connect

    Knox, S.J.; Wilson, F.D.; Greenberg, B.R.; Shifrine, M.; Rosenblatt, L.S.; Reeves, J.D.; Misra, H.

    1981-06-01

    In vitro radiation survival of peripheral blood T lymphocytes was studied in 15 clinically normal adults and 4 patients with Fanconi's anemia. Tritiated thymidine incorporation in a whole blood lymphocyte stimulation test (LST) and a newly developed whole blood T-lymphocyte colony assay were used to measure lymphocyte blastogenesis and colony formation in response to phytohemagglutinin (PHA) or concanavalin-A (Con-A) stimulation. Lymphocyte colony formation was found to be consistently more sensitive than the LST for detection of low-level radiation effects using both normal cells and lymphocytes from Fanconi's anemia patients. Lymphocytes from patients with Fanconi's anemia were significantly more sensitive to in vitro x-irradiation than lymphocytes from clinically normal individuals as measured by their ability to divide when stimulated by PHA in the LST (patients, D37 . 198 R; normals, D37 . 309 R, p . 0.057) and colony formation assay (patients, D37 . 53 R; normals, D37 . 109 R, p . 0.016). No significant difference in the radiosensitivity of the Con-A response was observed between the two groups. The PHA-responsive T-lymphocyte subpopulation in Fanconi's anemia patients appears to be intrinsically defective. The nature of this defect, significance in the disease process, and relevancy of these findings to the establishment of radiation protection standards are discussed.

  7. Novel approach to abuse the hyperactive K-Ras pathway for adenoviral gene therapy of colorectal cancer

    SciTech Connect

    Naumov, Inna; Kazanov, Dina; Lisiansky, Victoria; Starr, Alex; Aroch, Ilan; Shapira, Shiran; Kraus, Sarah; Arber, Nadir

    2012-01-15

    Background: Functional activation of oncogenic K-Ras signaling pathway plays an important role in the early events of colorectal carcinogenesis (CRC). K-Ras proto-oncogene is involved in 35-40% of CRC cases. Mutations in the Ras gene trigger the transduction of proliferative and anti-apoptotic signals, even in the absence of extra cellular stimuli. The objective of the current study was to use a gene-targeting approach to kill human CRC cells selectively harboring mutated K-Ras. Results: A recombinant adenovirus that carries a lethal gene, PUMA, under the control of a Ras responsive promoter (Ad-Py4-SV40-PUMA) was used selectively to target CRC cells (HCT116, SW480, DLD1 and RIE-Ras) that possess a hyperactive Ras pathway while using HT29 and RIE cells as a control that harbors wild type Ras and exhibit very low Ras activity. Control vector, without the Ras responsive promoter elements was used to assess the specificity of our 'gene therapy' approach. Both adenoviral vectors were assed in vitro and in xenograft model in vivo. Ad-Py4-SV40-PUMA showed high potency to induce {approx} 50% apoptosis in vitro, to abolish completely tumor formation by infecting cells with the Ad-Py4-SV40-PUMA prior xenografting them in nude mice and high ability to suppress by {approx} 35% tumor progression in vivo in already established tumors. Conclusions: Selective targeting of CRC cells with the activated Ras pathway may be a novel and effective therapy in CRC. The high potency of this adenoviral vector may help to overcome an undetectable micro metastasis that is the major hurdle in challenging with CRC.

  8. Frequent k- ras -2 mutations and p16(INK4A)methylation in hepatocellular carcinomas in workers exposed to vinyl chloride.

    PubMed

    Weihrauch, M; Benicke, M; Lehnert, G; Wittekind, C; Wrbitzky, R; Tannapfel, A

    2001-04-01

    Vinyl chloride (VC) is a know animal and human carcinogen associated with liver angiosarcomas (LAS) and hepatocellular carcinomas (HCC). In VC-associated LAS mutations of the K- ras -2 gene have been reported; however, no data about the prevalence of such mutations in VC associated HCCs are available. Recent data indicate K- ras -2 mutations induce P16 methylation accompanied by inactivation of the p16 gene. The presence of K- ras -2 mutations was analysed in tissue from 18 patients with VC associated HCCs. As a control group, 20 patients with hepatocellular carcinoma due to hepatitis B (n = 7), hepatitis C (n = 5) and alcoholic liver cirrhosis (n = 8) was used. The specific mutations were determined by direct sequencing of codon 12 and 13 of the K- ras -2 gene in carcinomatous and adjacent non-neoplastic liver tissue after microdissection. The status of p16 was evaluated by methylation-specific PCR (MSP), microsatellite analysis, DNA sequencing and immunohistochemical staining. All patients had a documented chronic quantitated exposure to VC (average 8883 ppmy, average duration: 245 months). K- ras -2 mutations were found in 6 of 18 (33%) examined VC-associated HCCs and in 3 cases of adjacent non-neoplastic liver tissue. There were 3 G --> A point mutations in the tumour tissue. All 3 mutations found in non-neoplastic liver from VC-exposed patients were also G --> A point mutations (codon 12- and codon 13-aspartate mutations). Hypermethylation of the 5' CpG island of the p16 gene was found in 13 of 18 examined carcinomas (72%). Of 6 cancers with K- ras -2 mutations, 5 specimens also showed methylated p16. Within the control group, K- ras -2 mutation were found in 3 of 20 (15%) examined HCC. p16 methylation occurred in 11 out of 20 (55%) patients. K- ras -2 mutations and p16 methylation are frequent events in VC associated HCCs. We observed a K- ras -2 mutation pattern characteristic of chloroethylene oxide, a carcinogenic metabolite of VC. Our results strongly

  9. STAT3 supports experimental K-RasG12D–induced murine myeloproliferative neoplasms dependent on serine phosphorylation

    PubMed Central

    Gough, Daniel J.; Marié, Isabelle J.; Lobry, Camille; Aifantis, Iannis

    2014-01-01

    Juvenile myelomonocytic leukemia, acute myeloid leukemia (AML), and other myeloproliferative neoplasms (MPNs) are genetically heterogeneous but frequently display activating mutations in Ras GTPases and activation of signal transducer and activator of transcription 3 (STAT3). Altered STAT3 activity is observed in up to 50% of AML correlating with poor prognosis. Activated STAT proteins, classically associated with tyrosine phosphorylation, support tumor development as transcription factors, but alternative STAT functions independent of tyrosine phosphorylation have been documented, including roles for serine-phosphorylated STAT3 in mitochondria supporting transformation by oncogenic Ras. We examined requirements for STAT3 in experimental murine K-Ras–dependent hematopoietic neoplasia. We show that STAT3 is phosphorylated on S727 but not Y705 in diseased animals. Moreover, a mouse with a point mutation abrogating STAT3 S727 phosphorylation displayed delayed onset and decreased disease severity with significantly extended survival. Activated K-Ras required STAT3 for cytokine-independent growth of myeloid progenitors in vitro, and mitochondrially restricted STAT3 and STAT3-Y705F, both transcriptionally inert mutants, supported factor-independent growth. STAT3 was dispensable for growth of normal or K-Ras–mutant myeloid progenitors in response to cytokines. However, abrogation of STAT3-S727 phosphorylation impaired factor-independent malignant growth. These data document that serine-phosphorylated mitochondrial STAT3 supports neoplastic hematopoietic cell growth induced by K-Ras. PMID:25150294

  10. Prevention of K-Ras- and Pten-mediated intravaginal tumors by treatment with camptothecin-loaded PLGA nanoparticles

    PubMed Central

    Blum, Jeremy S.; Weller, Caroline E.; Booth, Carmen J.; Babar, Imran A.; Liang, Xianping; Slack, Frank J.

    2014-01-01

    Primary squamous cell carcinoma of the vagina is an uncommon disease that often exhibits few symptoms before reaching an advanced stage. Topical intravaginal therapies for resolving precancerous and cancerous vaginal lesions have the potential to be non-invasive and safer alternatives to existing treatment options. Two factors limit the testing of this approach: lack of a preclinical intravaginal tumor model and absence of safe and effective topical delivery systems. In this study, we present both an inducible genetic model of vaginal squamous cell carcinoma in mice and a novel topical delivery system. Tumors were generated via activation of oncogenic K-Ras and inactivation of tumor suppressor Pten in LSL-K-RasG12D/+ PtenloxP/loxP mice. This was accomplished by exposing the vaginal epithelium to a recombinant adenoviral vector expressing Cre recombinase (AdCre). As early as 3 weeks after AdCre exposure exophytic masses protruding from the vagina were observed; these were confirmed to be squamous cell carcinoma by histology. We utilized this model to investigate an anticancer therapy based on poly(lactic-co-glycolic acid) (PLGA) nanoparticles loaded with camptothecin (CPT); our earlier work has shown that PLGA nanoparticles can penetrate the vaginal epithelium and provide sustained CPT release. Particles were lavaged into the vaginal cavity of AdCre-infected mice. None of the mice receiving CPT nanoparticles developed tumors. These results demonstrate a novel topical strategy to resolve precancerous and cancerous lesions in the female reproductive tract. PMID:25419505

  11. Long-term follow-up of patients with resected pancreatic cancer following vaccination against mutant K-ras.

    PubMed

    Wedén, Synne; Klemp, Marianne; Gladhaug, Ivar P; Møller, Mona; Eriksen, Jon Amund; Gaudernack, Gustav; Buanes, Trond

    2011-03-01

    K-ras mutations are frequently found in adenocarcinomas of the pancreas and can elicit mutation-specific immune responses. Targeting the immune system against mutant Ras may thus influence the clinical course of the disease. Twenty-three patients who were vaccinated after surgical resection for pancreatic adenocarcinoma (22 pancreaticoduodenectomies, one distal resection), in two previous Phase I/II clinical trials, were followed for more than 10 years with respect to long-term immunological T-cell reactivity and survival. The vaccine was composed of long synthetic mutant ras peptides designed mainly to elicit T-helper responses. Seventeen of 20 evaluable patients (85%) responded immunologically to the vaccine. Median survival for all patients was 27.5 months and 28 months for immune responders. The 5-year survival was 22% and 29%, respectively. Strikingly, 10-year survival was 20% (four patients out of 20 evaluable) versus zero (0/87) in a cohort of nonvaccinated patient treated in the same period. Three patients mounted a memory response up to 9 years after vaccination. The present observation of long-term immune response together with 10-year survival following surgical resection indicates that K-ras vaccination may consolidate the effect of surgery and represent an adjuvant treatment option for the future. PMID:20473937

  12. MEKs/ERKs inhibitor U0126 increases the radiosensitivity of rhabdomyosarcoma cells in vitro and in vivo by down regulating growth and DNA repair signals

    PubMed Central

    Marampon, Francesco; Gravina, Giovanni Luca; Di Rocco, Agnese; Bonfili, Pierluigi; Di Staso, Mario; Fardella, Caterina; Polidoro, Lorella; Ciccarelli, Carmela; Festuccia, Claudio; Popov, Vladimir M.; Pestell, Richard G.; Tombolini, Vincenzo; Zani, Bianca Maria

    2010-01-01

    Multimodal treatment has improved the outcome of many solid tumors, and in some cases the use of radiosensitizers has significantly contributed to this gain. Activation of the extracellular signaling kinase pathway (MEK/ERK) generally results in stimulation of cell growth and confers a survival advantage playing the major role in human cancer. The potential involvement of this pathway in cellular radiosensitivity remains unclear. We previously reported that the disruption of c-Myc through MEK/ERK inhibition blocks the expression of the transformed phenotype, affects in vitro and in vivo growth, angiogenic signaling, and induces myogenic differentiation in the embryonal rhabdomyosarcoma (ERMS) cell lines (RD). The present study was designed to examine whether the ERK pathway affects intrinsic radiosensitivity of rhabdomyosarcoma cancer cells. Exponentially growing human ERMS, RD, xenograft-derived RD-M1 and TE671 cell lines were used. The specific MEK/ERK inhibitor, U0126, reduced the clonogenic potential of the three cell lines, and was effected by radiation. U0126 inhibited phospho/active ERK1/2 and reduced DNAPKcs suggesting that ERKs and DNA-PKcs cooperate in radioprotection of rhabdomyosarcoma cells. The TE671 cell line-xenotransplanted in mice showed a reduction in tumor mass and increase in the time of tumor progression with U0126 treatment associated with reduced DNAPKcs, an effect enhanced by radiotherapy. Thus, our results show that MEK/ERK inhibition enhances radiosensitivity of rhabdomyosarcoma cells suggesting a rational approach in combination with radiotherapy. PMID:21220498

  13. Inhibition of UBE2D3 Expression Attenuates Radiosensitivity of MCF-7 Human Breast Cancer Cells by Increasing hTERT Expression and Activity

    PubMed Central

    Hu, Liu; Li, Fen; Ren, Li; Yu, Haijun; Liu, Yu; Xia, Ling; Lei, Han; Liao, Zhengkai; Zhou, Fuxiang; Xie, Conghua; Zhou, Yunfeng

    2013-01-01

    The known functions of telomerase in tumor cells include replenishing telomeric DNA and maintaining cell immortality. We have previously shown the existence of a negative correlation between human telomerase reverse transcriptase (hTERT) and radiosensitivity in tumor cells. Here we set out to elucidate the molecular mechanisms underlying regulation by telomerase of radiosensitivity in MCF-7 cells. Toward this aim, yeast two-hybrid (Y2H) screening of a human laryngeal squamous cell carcinoma radioresistant (Hep2R) cDNA library was first performed to search for potential hTERT interacting proteins. We identified ubiquitin-conjugating enzyme E2D3 (UBE2D3) as a principle hTERT-interacting protein and validated this association biochemically. ShRNA-mediated inhibition of UBE2D3 expression attenuated MCF-7 radiosensitivity, and induced the accumulation of hTERT and cyclin D1 in these cells. Moreover, down-regulation of UBE2D3 increased hTERT activity and cell proliferation, accelerating G1 to S phase transition in MCF-7 cells. Collectively these findings suggest that UBE2D3 participates in the process of hTERT-mediated radiosensitivity in human breast cancer MCF-7 cells by regulating hTERT and cyclin D1. PMID:23741361

  14. Knockdown of EphB1 receptor decreases medulloblastoma cell growth and migration and increases cellular radiosensitization

    PubMed Central

    Timofeeva, Olga; Pasquale, Elena B.; Hirsch, Kellen; MacDonald, Tobey J.; Dritschilo, Anatoly; Lee, Yi Chien; Henkemeyer, Mark; Rood, Brian; Jung, Mira; Wang, Xiao-Jing; Kool, Marcel

    2015-01-01

    The expression of members of the Eph family of receptor tyrosine kinases and their ephrin ligands is frequently dysregulated in medulloblastomas. We assessed the expression and functional role of EphB1 in medulloblastoma cell lines and engineered mouse models. mRNA and protein expression profiling showed expression of EphB1 receptor in the human medulloblastoma cell lines DAOY and UW228. EphB1 downregulation reduced cell growth and viability, decreased the expression of important cell cycle regulators, and increased the percentage of cells in G1 phase of the cell cycle. It also modulated the expression of proliferation, and cell survival markers. In addition, EphB1 knockdown in DAOY cells resulted in significant decrease in migration, which correlated with decreased β1-integrin expression and levels of phosphorylated Src. Furthermore, EphB1 knockdown enhanced cellular radiosensitization of medulloblastoma cells in culture and in a genetically engineered mouse medulloblastoma model. Using genetically engineered mouse models, we established that genetic loss of EphB1 resulted in a significant delay in tumor recurrence following irradiation compared to EphB1-expressing control tumors. Taken together, our findings establish that EphB1 plays a key role in medulloblastoma cell growth, viability, migration, and radiation sensitivity, making EphB1 a promising therapeutic target. PMID:25879388

  15. The HER2-Binding Affibody Molecule (ZHER2∶342)2 Increases Radiosensitivity in SKBR-3 Cells

    PubMed Central

    Ekerljung, Lina; Lennartsson, Johan; Gedda, Lars

    2012-01-01

    We have previously shown that the HER2-specific affibody molecule (ZHER2∶342)2 inhibits proliferation of SKBR-3 cells. Here, we continue to investigate its biological effects in vitro by studying receptor dimerization and clonogenic survival following irradiation. We found that (ZHER2∶342)2 sensitizes the HER2-overexpressing cell line SKBR-3 to ionizing radiation. The survival after exposure to (ZHER2∶342)2 and 8 Gy (S8Gy 0.006) was decreased by a factor four compared to the untreated (S8Gy 0.023). The low HER2-expressing cell line MCF-7 was more radiosensitive than SKBR-3 but did not respond to (ZHER2∶342)2. Treatment by (ZHER2∶342)2 strongly increased the levels of dimerized and phosphorylated HER2 even after 5 minutes of stimulation. The monomeric ZHER2∶342 does not seem to be able to induce receptor phosphorylation and dimerization or sensitize cells to irradiation. PMID:23166716

  16. Knockdown of EphB1 receptor decreases medulloblastoma cell growth and migration and increases cellular radiosensitization.

    PubMed

    Bhatia, Shilpa; Baig, Nimrah A; Timofeeva, Olga; Pasquale, Elena B; Hirsch, Kellen; MacDonald, Tobey J; Dritschilo, Anatoly; Lee, Yi Chien; Henkemeyer, Mark; Rood, Brian; Jung, Mira; Wang, Xiao-Jing; Kool, Marcel; Rodriguez, Olga; Albanese, Chris; Karam, Sana D

    2015-04-20

    The expression of members of the Eph family of receptor tyrosine kinases and their ephrin ligands is frequently dysregulated in medulloblastomas. We assessed the expression and functional role of EphB1 in medulloblastoma cell lines and engineered mouse models. mRNA and protein expression profiling showed expression of EphB1 receptor in the human medulloblastoma cell lines DAOY and UW228. EphB1 downregulation reduced cell growth and viability, decreased the expression of important cell cycle regulators, and increased the percentage of cells in G1 phase of the cell cycle. It also modulated the expression of proliferation, and cell survival markers. In addition, EphB1 knockdown in DAOY cells resulted in significant decrease in migration, which correlated with decreased β1-integrin expression and levels of phosphorylated Src. Furthermore, EphB1 knockdown enhanced cellular radiosensitization of medulloblastoma cells in culture and in a genetically engineered mouse medulloblastoma model. Using genetically engineered mouse models, we established that genetic loss of EphB1 resulted in a significant delay in tumor recurrence following irradiation compared to EphB1-expressing control tumors. Taken together, our findings establish that EphB1 plays a key role in medulloblastoma cell growth, viability, migration, and radiation sensitivity, making EphB1 a promising therapeutic target. PMID:25879388

  17. Activated kRas protects colon cancer cells from cucurbitacin-induced apoptosis; the role of p53 and p21

    PubMed Central

    Escandell, José M.; Kaler, Pawan; Recio, M. Carmen; Sasazuki, Takehiko; Shirasawa, Senji; Augenlicht, Leonard; Ríos, José-Luis; Klampfer, Lidija

    2008-01-01

    Cucurbitacins have been shown to inhibit proliferation in a variety of cancer cell lines. The aim of this study was to determine their biological activity in colon cancer cell lines that do not harbor activated STAT3, the key target of cucurbitacin. In order to establish the role of activated kRas in the responsiveness of cells to cucurbitacins, we performed experiments in isogenic colon cancer cell lines, HCT116 and Hke-3, which differ only by the presence of an activated kRas allele. We compared the activity of 23, 24-dihydrocucurbitacin B (DHCB) and cucurbitacin R (CCR), two cucurbitacins that we recently isolated, with cucurbitacin I (CCI), a cucurbitacin with established antitumorigenic activity. We showed that cucurbitacins induced dramatic changes in the cytoskeleton (collapse of actin and bundling of tubulin microfilaments), inhibited proliferation and finally induced apoptosis of both HCT116 and Hke3 cells. However, the presence of oncogenic k-Ras significantly decreased the sensitivity of cells to the three cucurbitacins tested, CCR, DHCB and CCI. We confirmed that mutational activation of kRas protects cells from cucurbitacin-induced apoptosis using nontransfromed intestinal epithelial cells with inducible expression of k-RasV12. Cucurbitacins induced the expression of p53 and p21 predominantly in HCT116 cells that harbor mutant Ras. Using HCT116 cells with targeted deletion of p53 or p21 we confirmed that p53 and p21 protect cells from apoptosis induced by cucurbitacins. These results demonstrated that sensitivity of human colon cancer cell lines to cucurbitacins depends on the kRas and p53/p21 status, and established that cucurbitacins can exert antitumorigenic activity in the absence of activated STAT3. PMID:18561895

  18. Activated kRas protects colon cancer cells from cucurbitacin-induced apoptosis: the role of p53 and p21.

    PubMed

    Escandell, José M; Kaler, Pawan; Recio, M Carmen; Sasazuki, Takehiko; Shirasawa, Senji; Augenlicht, Leonard; Ríos, José-Luis; Klampfer, Lidija

    2008-07-15

    Cucurbitacins have been shown to inhibit proliferation in a variety of cancer cell lines. The aim of this study was to determine their biological activity in colon cancer cell lines that do not harbor activated STAT3, the key target of cucurbitacin. In order to establish the role of activated kRas in the responsiveness of cells to cucurbitacins, we performed experiments in isogenic colon cancer cell lines, HCT116 and Hke-3, which differ only by the presence of an activated kRas allele. We compared the activity of 23, 24-dihydrocucurbitacin B (DHCB) and cucurbitacin R (CCR), two cucurbitacins that we recently isolated, with cucurbitacin I (CCI), a cucurbitacin with established antitumorigenic activity. We showed that cucurbitacins induced dramatic changes in the cytoskeleton (collapse of actin and bundling of tubulin microfilaments), inhibited proliferation and finally induced apoptosis of both HCT116 and Hke-3 cells. However, the presence of oncogenic kRas significantly decreased the sensitivity of cells to the three cucurbitacins tested, CCR, DHCB and CCI. We confirmed that mutational activation of kRas protects cells from cucurbitacin-induced apoptosis using nontransformed intestinal epithelial cells with inducible expression of kRasV12. Cucurbitacins induced the expression of p53 and p21 predominantly in HCT116 cells that harbor mutant Ras. Using HCT116 cells with targeted deletion of p53 or p21 we confirmed that p53 and p21 protect cells from apoptosis induced by cucurbitacins. These results demonstrated that sensitivity of human colon cancer cell lines to cucurbitacins depends on the kRas and p53/p21 status, and established that cucurbitacins can exert antitumorigenic activity in the absence of activated STAT3. PMID:18561895

  19. Modulation of tumor induction and progression of oncogenic K-ras-positive tumors in the presence of TGF- b1 haploinsufficiency.

    PubMed

    Pandey, Jyotsna; Umphress, Sarah M; Kang, Yang; Angdisen, Jerry; Naumova, Alena; Mercer, Kim L; Jacks, Tyler; Jakowlew, Sonia B

    2007-12-01

    Oncogenic K-ras is one of the most common genetic alterations in human lung adenocarcinomas. In addition, inactivation of clusters of tumor suppressor genes is required to bring about classical characteristics of cancer including angiogenesis as a prelude to invasion and metastasis. Transforming growth factor-beta (TGF-beta) 1 is a tumor suppressor gene that is implicated in lung cancer progression. Although in vitro studies have shown that TGF-beta1 and Ras pathways cooperate during tumorigenesis, the biology of interaction of TGF-beta1 and Ras has not been studied in in vivo tumorigenesis. We hypothesized that inactivation of TGF-beta1 in addition to oncogeneic activation of K-ras would lead to early initiation and faster progression to lung adenocarcinoma and invasion and metastasis. Heterozygous (HT) TGF-beta1 mice were mated with latent activatable (LA) mutated K-ras mice to generate TGF-beta1(+/+), K-ras LA (wild-type (WT)/LA) and TGF-beta1(+/-), K-ras LA (HT/LA) mice. Both HT/LA and WT/LA mice developed spontaneous lung tumors, but HT/LA mice progressed to adenocarcinomas significantly earlier compared with WT/LA mice. In addition, WT/LA adenocarcinomas had significantly higher angiogenic activity compared with HT/LA adenocarcinomas. Thus, while oncogenic K-ras mutation and insensitivity to the growth regulatory effects of TGF-beta1 is essential for initiation and progression of mouse lung tumors to adenocarcinoma, a full gene dosage of TGF-beta1 is required for tumor-induced angiogenesis and invasive potential. This study identifies a number of genes not previously associated with lung cancer that are involved in tumor induction and progression. In addition, we provide evidence that progression to invasive angiogenic lesions requires TGF-beta1 responsiveness in addition to Ras mutation. PMID:17690114

  20. The relationship between microvessel count and the expression of vascular endothelial growth factor, p53, and K-ras in non-small cell lung cancer.

    PubMed Central

    Kang, Y. H.; Kim, K. S.; Yu, Y. K.; Lim, S. C.; Kim, Y. C.; Park, K. O.

    2001-01-01

    Using immunohistochemical staining, we studied the relationship between the microvessel count (MC) and the expression of K-ras, mutant p53 protein, and vascular endothelial growth factor (VEGF) in 61 surgically resected non-small cell lung cancers (NSCLC) (42 squamous cell carcinoma, 14 adenocarcinoma, 2 large cell carcinoma, 2 adenosquamous carcinoma, and 1 mucoepidermoid carcinoma). MC of the tumors with lymph node (LN) metastasis was significantly higher than that of tumors without LN metastasis (66.1+/-23.1 vs. 33.8+/-13.1, p<0.05). VEGF was positive in 54 patients (88.5%). MC was 58.1+/-25.2 (mean+/-S.D.) in a x200 field, and it was significantly higher in VEGF(+) tumors than in VEGF(-) tumors (61.4+/-23.7 vs. 32.9+/-23.8, p<0.05). VEGF expression was higher in K-ras-positive or mutant p53-positive tumors than in negative tumors (p<0.05). MC was significantly higher in K-ras(+) tumors than in K-ras(-) tumors, although it did not differ according to the level of mutant p53 protein expression. Survival did not differ with VEGF, mutant p53, or K-ras expression, or the level of MC. In conclusion, there is a flow of molecular alterations from K-ras and p53, to VEGF expression, leading to angiogenesis and ultimately lymph node metastasis. Correlations between variables in close approximation and the lack of prognostic significance of individual molecular alterations suggest that tumorigenesis and metastasis are multifactorial processes. PMID:11511786

  1. Assessment of epidermal growth factor receptor mutation/copy number and K-ras mutation in esophageal cancer

    PubMed Central

    Guo, Kang; Wang, Wu-Ping; Jiang, Tao; Wang, Ju-Zheng; Chen, Zhao; Li, Yong; Zhou, Yong-An; Li, Xiao-Fei

    2016-01-01

    Background The molecular status of epidermal growth factor receptor (EGFR) in esophageal cancer has not been well elucidated. The purpose of the study was to investigate the prevalence of EGFR and K-ras mutation, and EGFR gene copy number status as well as its association with clinicopathologic characteristics, and also to identify the prognostic value of EGFR gene copy number in esophageal cancer. Methods EGFR mutation in exon 19/exon 21 and K-ras mutation in codon 12/codon 13 were detected by real-time PCR method, while EGFR gene copy number status was analyzed by fluorescent in situ hybridization (FISH). EGFR gene amplification and high polysomy were defined as high EGFR gene copy number status (FISH-positive), and all else were defined as low EGFR gene copy number status (FISH-negative). The relationship between EGFR gene copy number status and clinicpathologic characteristics was analyzed. Kaplan-Meier method and Cox proportional hazards regression model were employed to evaluate the effects of EGFR gene copy number status on the patients’ survival. Results A total of 57 esophageal squamous cell carcinoma (ESCC) patients and 9 esophageal adenocarcinoma (EADC) patients were enrolled in the study. EGFR mutation was identified in one patient who was diagnosed as ESCC with stage IIIC disease. K-ras mutation was identified in one patient who was diagnosed as EADC. In all, 34 of 66 (51.5%) samples were detected as FISH-positive, which includes 30 ESCC and 4 EADC tumor samples. The correlation analysis showed that FISH-positive was significantly associated with the tumor stage (P=0.019) and lymph node metastasis (P=0.005) in esophageal cancer patients, and FISH-positive was also significantly associated with the tumor stage (P=0.007) and lymph node metastasis (P=0.008) in ESCC patients. Cox regression analysis showed that high EGFR gene copy number was not a significant predictor of a poor outcome for esophageal cancer patients (P=0.251) or for ESCC patients (P=0

  2. A method for the second-site screening of K-Ras in the presence of a covalently attached first-site ligand.

    PubMed

    Sun, Qi; Phan, Jason; Friberg, Anders R; Camper, DeMarco V; Olejniczak, Edward T; Fesik, Stephen W

    2014-09-01

    K-Ras is a well-validated cancer target but is considered to be "undruggable" due to the lack of suitable binding pockets. We previously discovered small molecules that bind weakly to K-Ras but wanted to improve their binding affinities by identifying ligands that bind near our initial hits that we could link together. Here we describe an approach for identifying second site ligands that uses a cysteine residue to covalently attach a compound for tight binding to the first site pocket followed by a fragment screen for binding to a second site. This approach could be very useful for targeting Ras and other challenging drug targets. PMID:25087006

  3. Cathepsin L suppression increases the radiosensitivity of human glioma U251 cells via G2/M cell cycle arrest and DNA damage

    PubMed Central

    Zhang, Qing-qing; Wang, Wen-juan; Li, Jun; Yang, Neng; Chen, Gang; Wang, Zhong; Liang, Zhong-qin

    2015-01-01

    Aim: Cathepsin L is a lysosomal cysteine protease that plays important roles in cancer tumorigenesis, proliferation and chemotherapy resistance. The aim of this study was to determine how cathepsin L regulated the radiosensitivity of human glioma cells in vitro. Methods: Human glioma U251 cells (harboring the mutant type p53 gene) and U87 cells (harboring the wide type p53 gene) were irradiated with X-rays. The expression of cathepsin L was analyzed using Western blot and immunofluorescence assays. Cell survival and DNA damage were evaluated using clonogenic and comet assays, respectively. Flow cytometry was used to detect the cell cycle distribution. Apoptotic cells were observed using Hoechst 33258 staining and fluorescence microscopy. Results: Irradiation significantly increased the cytoplasmic and nuclear levels of cathepsin L in U251 cells but not in U87 cells. Treatment with the specific cathepsin L inhibitor Z-FY-CHO (10 μmol/L) or transfection with cathepsin L shRNA significantly increased the radiosensitivity of U251 cells. Both suppression and knockdown of cathepsin L in U251 cells increased irradiation-induced DNA damage and G2/M phase cell cycle arrest. Both suppression and knockdown of cathepsin L in U251 cells also increased irradiation-induced apoptosis, as shown by the increased levels of Bax and decreased levels of Bcl-2. Conclusion: Cathepsin L is involved in modulation of radiosensitivity in human glioma U251 cells (harboring the mutant type p53 gene) in vitro. PMID:26095040

  4. Therapeutic inhibition of TRF1 impairs the growth of p53-deficient K-RasG12V-induced lung cancer by induction of telomeric DNA damage

    PubMed Central

    García-Beccaria, María; Martínez, Paula; Méndez-Pertuz, Marinela; Martínez, Sonia; Blanco-Aparicio, Carmen; Cañamero, Marta; Mulero, Francisca; Ambrogio, Chiara; Flores, Juana M; Megias, Diego; Barbacid, Mariano; Pastor, Joaquín; Blasco, Maria A

    2015-01-01

    Telomeres are considered anti-cancer targets, as telomere maintenance above a minimum length is necessary for cancer growth. Telomerase abrogation in cancer-prone mouse models, however, only decreased tumor growth after several mouse generations when telomeres reach a critically short length, and this effect was lost upon p53 mutation. Here, we address whether induction of telomere uncapping by inhibition of the TRF1 shelterin protein can effectively block cancer growth independently of telomere length. We show that genetic Trf1 ablation impairs the growth of p53-null K-RasG12V-induced lung carcinomas and increases mouse survival independently of telomere length. This is accompanied by induction of telomeric DNA damage, apoptosis, decreased proliferation, and G2 arrest. Long-term whole-body Trf1 deletion in adult mice did not impact on mouse survival and viability, although some mice showed a moderately decreased cellularity in bone marrow and blood. Importantly, inhibition of TRF1 binding to telomeres by small molecules blocks the growth of already established lung carcinomas without affecting mouse survival or tissue function. Thus, induction of acute telomere uncapping emerges as a potential new therapeutic target for lung cancer. PMID:25971796

  5. Binding hotspots on K-Ras: consensus ligand binding sites and other reactive regions from probe-based molecular dynamics analysis

    PubMed Central

    Prakash, Priyanka; Hancock, John F.; Gorfe, Alemayehu A.

    2015-01-01

    We have used probe-based molecular dynamics (pMD) simulations to search for interaction hotspots on the surface of the therapeutically highly relevant oncogenic K-Ras G12D. Combining the probe-based query with an ensemble-based pocket identification scheme and an analysis of existing Ras-ligand complexes, we show that (i) pMD is a robust and cost-effective strategy for binding site identification, (ii) all four of the previously reported ligand binding sites are suitable for structure-based ligand design, and (iii) in some cases probe binding and expanded sampling of configurational space enable pocket expansion and increase the likelihood of site identification. Furthermore, by comparing the distribution of hotspots in non-pocket-like regions with known protein- and membrane-interacting interfaces, we propose that pMD has the potential to predict surface patches responsible for protein-biomolecule interactions. These observations have important implications for future drug design efforts and will facilitate the search for potential interfaces responsible for the proposed transient oligomerization or interaction of Ras with other biomolecules in the cellular milieu. PMID:25740554

  6. Aerosol delivery of beclin1 enhanced the anti-tumor effect of radiation in the lungs of K-rasLA1 mice.

    PubMed

    Shin, Ji-Young; Lim, Hwang-Tae; Minai-Tehrani, Arash; Noh, Mi-Suk; Kim, Ji-Eun; Kim, Ji-Hye; Jiang, Hu-Lin; Arote, Rohidas; Kim, Doo-Yeol; Chae, Chanhee; Lee, Kee-Ho; Kim, Mi-Sook; Cho, Myung-Haing

    2012-07-01

    Radiotherapy alone has several limitations for treating lung cancer. Inhalation, a non-invasive approach for direct delivery of therapeutic agents to the lung, may help to enhance the therapeutic efficacy of radiation. Up-regulating beclin1, known as a tumor suppressor gene that plays a major role in autophagy, may sensitize tumors and lead to tumor regression in lungs of K-ras(LA1) lung cancer model mice. To minimize the side-effects of radiotherapy, fractionated exposures (five times, 24-h interval) with low dose (2 Gy) of radiation to the restricted area (thorax, 2 cm) were conducted. After sensitizing the lungs with radiation, beclin1, complexed with a nano-sized biodegradable poly(ester amine), was prepared and delivered into the murine lung via aerosol three times/week for four weeks. In a histopathological analysis, animals treated with beclin1 and radiation showed highly significant tumor regression and low progression to adenocarcinoma. An increase in the number of autophagic vacuoles and secondary lysosomes was detected. Dissociation of beclin1-bcl2 stimulated autophagy activation and showed a synergistic anti-tumor effect by inhibiting the Akt-mTOR pathway, cell proliferation and angiogenesis. The combination of radiation with non-invasive aerosol delivery of beclin1 may provide a prospect for developing novel therapy regimens applicable in clinics. PMID:22843615

  7. Identification and Characterization of a Small Inhibitory Peptide That Can Target DNA-PKcs Autophosphorylation and Increase Tumor Radiosensitivity

    SciTech Connect

    Sun Xiaonan; Yang Chunying; Liu Hai; Wang Qi; Wu Shixiu; Li Xia; Xie Tian; Brinkman, Kathryn L.; Teh, Bin S.; Butler, E. Brian; Xu Bo; Zheng, Shu

    2012-12-01

    Purpose: The DNA protein kinase catalytic subunit (DNA-PKcs) is one of the critical elements involved in the DNA damage repair process. Inhibition of DNA-PKcs results in hypersensitivity to ionizing radiation (IR); therefore, this approach has been explored to develop molecular targeted radiosensitizers. Here, we aimed to develop small inhibitory peptides that could specifically target DNA-PKcs autophosphorylation, a critical step for the enzymatic activation of the kinase in response to IR. Methods and Materials: We generated several small fusion peptides consisting of 2 functional domains, 1 an internalization domain and the other a DNA-PKcs autophosphorylation inhibitory domain. We characterized the internalization, toxicity, and radiosensitization activities of the fusion peptides. Furthermore, we studied the mechanisms of the inhibitory peptides on DNA-PKcs autophosphorylation and DNA repair. Results: We found that among several peptides, the biotin-labeled peptide 3 (BTW3) peptide, which targets DNA-PKcs threonine 2647 autophosphorylation, can abrogate IR-induced DNA-PKcs activation and cause prolonged {gamma}-H2AX focus formation. We demonstrated that BTW3 exposure led to hypersensitivity to IR in DNA-PKcs-proficient cells but not in DNA-PKcs-deficient cells. Conclusions: The small inhibitory peptide BTW3 can specifically target DNA-PKcs autophosphorylation and enhance radiosensitivity; therefore, it can be further developed as a novel class of radiosensitizer.

  8. The anti-malarial atovaquone increases radiosensitivity by alleviating tumour hypoxia

    PubMed Central

    Ashton, Thomas M.; Fokas, Emmanouil; Kunz-Schughart, Leoni A.; Folkes, Lisa K.; Anbalagan, Selvakumar; Huether, Melanie; Kelly, Catherine J.; Pirovano, Giacomo; Buffa, Francesca M.; Hammond, Ester M.; Stratford, Michael; Muschel, Ruth J.; Higgins, Geoff S.; McKenna, William Gillies

    2016-01-01

    Tumour hypoxia renders cancer cells resistant to cancer therapy, resulting in markedly worse clinical outcomes. To find clinical candidate compounds that reduce hypoxia in tumours, we conduct a high-throughput screen for oxygen consumption rate (OCR) reduction and identify a number of drugs with this property. For this study we focus on the anti-malarial, atovaquone. Atovaquone rapidly decreases the OCR by more than 80% in a wide range of cancer cell lines at pharmacological concentrations. In addition, atovaquone eradicates hypoxia in FaDu, HCT116 and H1299 spheroids. Similarly, it reduces hypoxia in FaDu and HCT116 xenografts in nude mice, and causes a significant tumour growth delay when combined with radiation. Atovaquone is a ubiquinone analogue, and decreases the OCR by inhibiting mitochondrial complex III. We are now undertaking clinical studies to assess whether atovaquone reduces tumour hypoxia in patients, thereby increasing the efficacy of radiotherapy. PMID:27453292

  9. The anti-malarial atovaquone increases radiosensitivity by alleviating tumour hypoxia.

    PubMed

    Ashton, Thomas M; Fokas, Emmanouil; Kunz-Schughart, Leoni A; Folkes, Lisa K; Anbalagan, Selvakumar; Huether, Melanie; Kelly, Catherine J; Pirovano, Giacomo; Buffa, Francesca M; Hammond, Ester M; Stratford, Michael; Muschel, Ruth J; Higgins, Geoff S; McKenna, William Gillies

    2016-01-01

    Tumour hypoxia renders cancer cells resistant to cancer therapy, resulting in markedly worse clinical outcomes. To find clinical candidate compounds that reduce hypoxia in tumours, we conduct a high-throughput screen for oxygen consumption rate (OCR) reduction and identify a number of drugs with this property. For this study we focus on the anti-malarial, atovaquone. Atovaquone rapidly decreases the OCR by more than 80% in a wide range of cancer cell lines at pharmacological concentrations. In addition, atovaquone eradicates hypoxia in FaDu, HCT116 and H1299 spheroids. Similarly, it reduces hypoxia in FaDu and HCT116 xenografts in nude mice, and causes a significant tumour growth delay when combined with radiation. Atovaquone is a ubiquinone analogue, and decreases the OCR by inhibiting mitochondrial complex III. We are now undertaking clinical studies to assess whether atovaquone reduces tumour hypoxia in patients, thereby increasing the efficacy of radiotherapy. PMID:27453292

  10. DETECTION OF K-RAS AND P53 MUTATIONS IN SPUTUM SAMPLES OF LUNG CANCER PATIENTS USING LASER CAPTURE MICRODISSECTION MICROSCOPE AND MUTATION ANALYSIS

    EPA Science Inventory

    Detection of K-ras and p53 Mutations in Sputum Samples of Lung Cancer Patients Using Laser Capture Microdissection Microscope and Mutation Analysis

    Phouthone Keohavong a,*, Wei-Min Gao a, Kui-Cheng Zheng a, Hussam Mady b, Qing Lan c, Mona Melhem b, and Judy Mumford d.
    <...

  11. Comparison of a PNA clamp PCR and an ARMS/Scorpion PCR assay for the detection of K-ras mutations.

    PubMed

    Nordgård, Oddmund; Oltedal, Satu; Janssen, Emiel A M; Gilje, Bjørnar; Kørner, Hartwig; Tjensvoll, Kjersti; Smaaland, Rune

    2012-03-01

    Point mutations in the K-ras gene have been shown to confer resistance against epidermal growth factor receptor-directed therapy of metastatic colorectal cancer. Accordingly, K-ras mutation testing has become mandatory in hospitals offering such treatment. We compared the performance and reagent costs of 2 sensitive methods for detection of K-ras mutations: a peptide nucleic acid (PNA) clamp polymerase chain reaction (PCR) assay and a commercially available amplification refractory mutation system/Scorpion (ARMS/S) PCR assay. Both methods were applied in parallel to 101 formalin-fixed, paraffin-embedded tumor and metastasis samples from patients with colon cancer. The PNA clamp PCR assay detected K-ras mutations in 35% (35 of 101) of the samples, whereas the ARMS/S PCR assay detected mutations in 27% (27 of 101) of them. There was 92% (93 of 101) concordance between the 2 methods and the κ coefficient for the comparison was 0.82. The 8 discordant cases were exclusively positive by PNA clamp PCR. Finally, the reagent costs of the PNA clamp PCR assay were estimated to be at least 20 times lower than the ARMS/S assay. We concluded that the high performance and low costs associated with the PNA clamp PCR assay encourage its use in the administration of personalized epidermal growth factor receptor-directed therapy. PMID:22306670

  12. Identification and characterization of a new G-quadruplex forming region within the kRAS promoter as a transcriptional regulator.

    PubMed

    Morgan, Rhianna K; Batra, Harshul; Gaerig, Vanessa C; Hockings, Jennifer; Brooks, Tracy A

    2016-02-01

    kRAS is one of the most prevalent oncogenic aberrations. It is either upregulated or mutationally activated in a multitude of cancers, including pancreatic, lung, and colon cancers. While a significant effort has been made to develop drugs that target kRAS, their clinical activity has been disappointing due to a variety of mechanistic hurdles. The presented works describe a novel mechanism and molecular target to downregulate kRAS expression--a previously undescribed G-quadruplex (G4) secondary structure within the proximal promoter acting as a transcriptional silencer. There are three distinct guanine-rich regions within the core kRAS promoter, including a previously examined region (G4near). Of these regions, the most distal region does not form an inducible and stable structure, whereas the two more proximal regions (termed near and mid) do form strong G4s. G4near is predominantly a tri-stacked structure with a discontinuous guanine run incorporated; G4mid consists of seven distinct runs of continuous guanines and forms numerous competing isoforms, including a stable three-tetrad stacked mixed parallel and antiparallel loop structures with longer loops of up to 10 nucleotides. Comprehensive analysis of the regulation of transcription by higher order structures has revealed that the guanine-rich region in the middle of the core promoter, termed G4mid, is a stronger repressor of promoter activity than G4near. Using the extensive guanine-rich region of the kRAS core promoter, and particularly the G4mid structure, as the primary target, future drug discovery programs will have potential to develop a potent, specifically targeted small molecule to be used in the treatment of pancreatic, ovarian, lung, and colon cancers. PMID:26597160

  13. The farnesyltransferase inhibitor, LB42708, inhibits growth and induces apoptosis irreversibly in H-ras and K-ras-transformed rat intestinal epithelial cells

    SciTech Connect

    Kim, Han-Soo; Kim, Ju Won; Gang, Jingu; Wen, Jing; Koh, Sang Seok; Koh, Jong Sung; Chung, Hyun-Ho; Song, Si Young . E-mail: gisong@yumc.yonsei.ac.kr

    2006-09-15

    LB42708 (LB7) and LB42908 (LB9) are pyrrole-based orally active farnesyltransferase inhibitors (FTIs) that have similar structures. The in vitro potencies of these compounds against FTase and GGTase I are remarkably similar, and yet they display different activity in apoptosis induction and morphological reversion of ras-transformed rat intestinal epithelial (RIE) cells. Both FTIs induced cell death despite K-ras prenylation, implying the participation of Ras-independent mechanism(s). Growth inhibition by these two FTIs was accompanied by G1 and G2/M cell cycle arrests in H-ras and K-ras-transformed RIE cells, respectively. We identified three key markers, p21{sup CIP1/WAF1}, RhoB and EGFR, that can explain the differences in the molecular mechanism of action between two FTIs. Only LB7 induced the upregulation of p21{sup CIP1/WAF1} and RhoB above the basal level that led to the cell cycle arrest and to distinct morphological alterations of ras-transformed RIE cells. Both FTIs successfully inhibited the ERK and activated JNK in RIE/K-ras cells. While the addition of conditioned medium from RIE/K-ras reversed the growth inhibition of ras-transformed RIE cells by LB9, it failed to overcome the growth inhibitory effect of LB7 in both H-ras- and K-ras-transformed RIE cells. We found that LB7, but not LB9, decreased the expression of EGFRs that confers the cellular unresponsiveness to EGFR ligands. These results suggest that LB7 causes the induction of p21{sup CIP1/WAF1} and RhoB and downregulation of EGFR that may serve as critical steps in the mechanism by which FTIs trigger irreversible inhibitions on the cell growth and apoptosis in ras-transformed cells.

  14. Transcriptional profiling of immortalized and K-ras-transformed mouse fibroblasts upon PKA stimulation by forskolin in low glucose availability.

    PubMed

    Chiaradonna, Ferdinando; Pirola, Yuri; Ricciardiello, Francesca; Palorini, Roberta

    2016-09-01

    Forskolin (FSK) induces activation of protein kinase A (PKA). This activation protects specifically some cancer cells from death induced by glucose starvation. Cell effects upon FSK treatment prompted us to investigate in detail the physiological role of PKA in the activation of pro-survival mechanisms in glucose starvation. In this regard we performed a microarray analysis of normal NIH3T3 and transformed NIH3T3-K-ras mouse fibroblasts cultured at 1 mM glucose and daily treated or not with 10 μM FSK until 72 h of growth, when the samples were collected. The microarray is deposited into Gene Expression Omnibus under Series GSE68266. The microarray data revealed that the activation of PKA regulates the expression of genes involved in metabolic, stress-response and pro-survival processes, like glutamine metabolism, autophagy and unfolded protein response, preventing cancer cell death in glucose starvation. Altogether these findings suggest that PKA activation, by inducing a complex transcriptional program, leads to cancer survival in nutrient stress, a typical feature of developing tumor. These transcriptional data, identifying this important role of PKA, will be useful to identify novel target in cancer therapy. PMID:27486565

  15. Ultra-sensitive biosensor for K-ras gene detection using enzyme capped gold nanoparticles conjugates for signal amplification.

    PubMed

    Fang, Xian; Bai, Lijuan; Han, Xiaowei; Wang, Jiao; Shi, Anqi; Zhang, Yuzhong

    2014-09-01

    In this study, an ultra-sensitive hairpin DNA-based electrochemical DNA biosensor for K-ras gene detection is described. Gold nanoparticles (Au-NPs) and horseradish peroxidase (HRP)-streptavidin capped Au-NPs (HAS) conjugates are used for signal amplification. Initially, hairpin DNA dually labeled with thiol at its 5' end and with biotin at its 3' end is immobilized on the surface of Au-NPs modified electrode, and the hairpin DNA is in a "closed" state; hence, the HAS conjugates are shielded from being approached by the biotin due to steric hindrance. However, in the presence of target DNA, the target DNA hybridizes with the loop structure of hairpin DNA and causes conformational change, resulting in biotin forced away from the electrode surface, thereby becoming accessible for the HAS conjugates. Thus, the HAS conjugates are linked to the electrode surface via the specific interaction between biotin and streptavidin. Electrochemical detection was performed in phosphate-buffered saline (PBS) containing tetramethylbenzidine (TMB) and H2O2. Under optimal conditions, the peak current differences (ΔI) are linear with the target DNA in the range from 0.1 fM to 1 nM with a detection limit of 0.035 fM. Furthermore, this biosensor also demonstrates its excellent specificity for single-base mismatched DNA. PMID:24939462

  16. Zerumbone increases oxidative stress in a thiol-dependent ROS-independent manner to increase DNA damage and sensitize colorectal cancer cells to radiation.

    PubMed

    Deorukhkar, Amit; Ahuja, Niharika; Mercado, Armando-Lopez; Diagaradjane, Parmeswaran; Raju, Uma; Patel, Nalini; Mohindra, Pranshu; Diep, Nga; Guha, Sushovan; Krishnan, Sunil

    2015-02-01

    Locally advanced rectal cancers are treated with neoadjuvant chemoradiation therapy followed by surgery. In a minority (~20%) of patients, no tumor is present at the time of surgery; these patients with a complete pathologic response (pathCR) to neoadjuvant therapy have better treatment outcomes. Unfortunately, the inherent radioresistance of colorectal cancer (CRC) cells dictates that the majority of patients do not achieve a pathCR. Efforts to improve these odds have fueled the search for novel, relatively less-toxic radiosensitizers with distinct molecular mechanism(s) and broad-spectrum anticancer activities. Here, we use zerumbone, a sesquiterpene from the edible ginger (Zingiber zerumbet Smith), to enhance radiosensitivity of CRC cells. Short exposure to zerumbone (7 h) profoundly sensitized CRC cells, independent of their p53 or k-RAS status. Zerumbone enhanced radiation-induced cell cycle arrest (G2/M), increased radiation-induced apoptosis, but induced little apoptosis by itself. Zerumbone significantly enhanced radiation-induced DNA damage, as evident by delayed resolution of post-irradiation nuclear γH2AX foci, whereas zerumbone treatment alone did not induce γH2AX foci formation. Zerumbone pretreatment inhibited radiation-induced nuclear expression of DNA repair proteins ataxia-telangiectasia mutated (ATM) and DNA-PKcs. Interestingly, zerumbone-mediated radiosensitization did not involve reactive oxygen species (ROS), but was mediated through depletion of cellular glutathione (GSH). Ability of only thiol-based antioxidants to abrogate zerumbone-mediated radiosensitization further corroborated this hypothesis. The α,β-unsaturated carbonyl group in zerumbone was found to be essential for its bioactivity as zerumbone analog α-Humulene that lacks this functional group, could neither radiosensitize CRC cells, nor deplete cellular GSH. Our studies elucidate novel mechanism(s) of zerumbone's ability to enhance CRC radiosensitivity. PMID:25450478

  17. A Crosstalk Between K ras (Kirsten Rat Sarcoma Viral Oncogene Homologue) and Adherence Molecular Complex Leads to Disassociation of Cells-A Possible Contribution Towards Metastasis in Colorectal Cancer.

    PubMed

    Murtaza, Bibi Nazia; Doak, Shareen; Morgan, Claire; Nadeem, Muhammad Shahid; Al-Ghanim, Khalid A; Shakoori, Abdul Rauf

    2016-10-01

    Constitutive activation of mutant K ras (Kirsten rat sarcoma viral oncogene homologue) and disassembly of E-cadherin-catenin complex (E-cadherin, α-catenin, β-catenin, and γ-catenin) play an important role in apoptosis, differentiation, and cell proliferation. In this study, the expression pattern of K ras and E-cadherin-catenin complex has been evaluated in normal and mutant colorectal cancer cell lines with an object to determine its impact on disassociation of cells from one another. We addressed the expression analysis of K ras with reference to its association with adherence molecules in two colorectal cancer cell lines, that is, Caco-2 (wild type K ras served as a control) and DLD1 (heterozygous mutation at codon 13) at message level by qRT-PCR and translational level by western blotting. Compared to the control Caco-2 cell lines, the K ras in DLD1 cell lines showed slightly higher values while α-catenin showed a slight lower (1.3-folds), β-catenin and E-cadherin showed significantly lower expression (4.2-fold decrease). It can be inferred that a possible cross talk exists between K ras and adherent junction mediated signalling. Mutation at codon 13 (G to D) leads to the overexpression of K ras and reduced expression of adherent junction complex resulting in metastasis. J. Cell. Biochem. 117: 2340-2345, 2016. © 2016 Wiley Periodicals, Inc. PMID:26945839

  18. A method for the second-site screening of K-Ras in the presence of a covalently attached first-site ligand

    PubMed Central

    Sun, Qi; Phan, Jason; Friberg, Anders R.; Camper, DeMarco V.; Olejniczak, Edward T.; Fesik, Stephen W.

    2015-01-01

    K-Ras is a well-validated cancer target but is considered to be “undruggable” due to the lack of suitable binding pockets. We previously discovered small molecules that bind weakly to K-Ras but wanted to improve their binding affinities by identifying ligands that bind near our initial hits that we could link together. Here we describe an approach for identifying second site ligands that uses a cysteine residue to covalently attach a compound for tight binding to the first site pocket followed by a fragment screen for binding to a second site. This approach could be very useful for targeting Ras and other challenging drug targets. PMID:25087006

  19. Analysis of p53, K-ras gene mutation & Helicobacter pylori infection in patients with gastric cancer & peptic ulcer disease at a tertiary care hospital in north India

    PubMed Central

    Saxena, Ashish; Shukla, Sanket Kumar; Prasad, Kashi Nath; Ghoshal, Uday Chand

    2012-01-01

    Background & objectives: Mutations in the oncogene and tumour suppressor genes play an important role in carcinogenesis. We investigated the association of p53 and K-ras gene mutation and Helicobacter pylori infection in patients with gastric cancer (GC) and peptic ulcer disease (PUD) attending a tertiary care hospital in north India. Methods: In total, 348 adult patients [62 GC, 45 PUD and 241 non-ulcer dyspepsia (NUD)] who underwent an upper gastrointestinal endoscopy were enrolled. H. pylori infection was diagnosed by rapid urease test, culture, histopathology and PCR. Mutation in the exon 5-8 of p53 gene was analyzed by PCR-single stranded conformational polymorphism (SSCP) and confirmed by sequence analysis. K-ras gene codon 12 mutation was analyzed by PCR-based restriction fragment length polymorphism. Results: Overall p53 gene mutation was found in 4.6 per cent of the study population, and its distribution in GC, PUD and NUD was 21, 4.4 and 0.4 per cent, respectively. p53 gene mutation was significantly higher in patients with GC than PUD (P<0.05) and NUD (P<0.001). No difference in p53 gene mutation was observed between H. pylori infected and non-infected individuals. K-ras gene mutation was absent in all the patients. Interpretation & conclusions: Our results show that p53 gene mutation may be associated with gastric carcinogenesis independent to H. pylori infection and absence of K-ras gene mutation questions its role in the pathogenesis of GC and PUD in Indian patients. PMID:23168708

  20. Targeting the K-Ras/PDEδ protein-protein interaction: the solution for Ras-driven cancers or just another therapeutic mirage?

    PubMed

    Frett, Brendan; Wang, Yuanxiang; Li, Hong-Yu

    2013-10-01

    The holy grail, finally? After years of unsuccessful attempts at drugging the Ras oncogene, a recent paper by Zimmerman et al. has revealed the possibility of inhibiting Ras signaling on a clinically relevant level by blocking the K-Ras/PDEδ protein-protein interaction. The results, reported in Nature, are highlighted herein with future implications and directions to evaluate the full clinical potential of this research. PMID:23939923

  1. K-ras oncogene DNA sequences in pink salmon in streams impacted by the Exxon Valdez oil spill: no evidence of oil-induced heritable mutations.

    PubMed

    Cronin, Matthew A; Wickliffe, Jeffrey K; Dunina, Yelena; Baker, Robert J

    2002-08-01

    It was hypothesized in previous studies that the Exxon Valdez oil spill in Prince William Sound, Alaska, induced heritable mutations and resulted in mortality of pink salmon (Oncorhynchus gorbuscha) embryos. In one of these studies, laboratory exposure of pink salmon embryos to crude oil resulted in apparent mutation-induction in exon 1 and exon 2 of the K-ras oncogene, but no fish from the area impacted by the oil spill were analyzed. We assessed K-ras exon 1 and exon 2 DNA sequences in pink salmon from five streams that were oiled and five streams that were not oiled by the Exxon Valdez oil spill in Prince William Sound, and two streams with natural oil seeps and one stream without seeps on the Alaska Peninsula. Of the 79 fish analyzed for exon 1 and the 89 fish analyzed for exon 2, none had the nucleotide substitutions representing the mutations induced in the laboratory study. Other variable nucleotides occurred in similar proportions in oiled and non-oiled streams and probably represent natural allelic variation. These data do not support the hypothesis that heritable mutations in the K-ras gene were induced by the Exxon Valdez oil spill or oil seeps. PMID:12211696

  2. Aerosol delivery of eukaryotic translation initiation factor 4E-binding protein 1 effectively suppresses lung tumorigenesis in K-rasLA1 mice.

    PubMed

    Chang, S-H; Kim, J-E; Lee, J-H; Minai-Tehrani, A; Han, K; Chae, C; Cho, Y-H; Yun, J-H; Park, K; Kim, Y-S; Cho, M-H

    2013-06-01

    Conventional radiotherapy or chemotherapy for the long-term survival of patients with lung cancer is still difficult for treatment in metastatic and advanced tumors. Therefore, the safe and effective approaches to the treatment of lung cancer are needed. In this study, the effect of delivered eukaryotic translation initiation factor 4E (eIF4E)-binding protein 1 (4E-BP1) on lung cancer progression was evaluated. Recombinant adeno-associated virus (rAAV)-M3/4E-BP1 was delivered into 6-week-old K-rasLA1 lung cancer model mice through a nose-only inhalation system twice a week for 4 weeks. Long-term repeated delivery of 4E-BP1 effectively reduced tumor progression in the lungs of K-rasLA1 mice. Reduction of eIF4E by overexpression of 4E-BP1 resulted in suppression of cap-dependent protein expression of basic fibroblast growth factor (bFGF or FGF-2) and vascular endothelial growth factor (VEGF). In addition, delivered 4E-BP1 inhibited the proliferation of lung cancer cells in K-rasLA1 mice model. Our results suggest that long-term repeated viral delivery of 4E-BP1 may provide a useful tool for designing lung cancer treatment. PMID:23640516

  3. Resveratrol-Induced Apoptosis and Increased Radiosensitivity in CD133-Positive Cells Derived From Atypical Teratoid/Rhabdoid Tumor

    SciTech Connect

    Kao, C.-L.; Huang, P.-I; Tsai, P.-H.; Tsai, M.-L.; Lo, J.-F.; Lee, Y.-Y.; Chen, Y.-J.; Chen, Y.-W.; Chiou, S.-H.

    2009-05-01

    Purpose: CD133 has recently been proposed as a marker for cancer stem-like cells (CSC) in brain tumors. The aim of the present study was to investigate the possible role of resveratrol (RV) in radiosensitivity of CD133-positive/-negative cells derived from atypical teratoid/rhabdoid tumors (AT/RT-CD133{sup +/-}). Materials and Methods: AT/RT-CD133{sup +/-} were isolated and characterized by flow cytometry and quantitative real-time reverse transcription-polymerase chain reaction, and then treated with RV at different doses. Migratory ability, colony formation, apoptotic activity, and xenotransplantation were assessed for RV alone, ionizing radiation (IR) alone, and IR with RV conditions. Results: AT/RT-CD133{sup +} displayed enhanced self-renewal and highly coexpressed 'stem cell' genes and drug-resistant genes, in addition to showing significant resistance to chemotherapeutic agents and radiotherapy as compared with CD133{sup -} cells. After treatment with 200 {mu}M RV, the in vitro proliferation rates and in vivo tumor restoration abilities of ATRT-CD133{sup +} were dramatically inhibited. Importantly, treatment with 150 {mu}M RV can effectively inhibit the expression of drug-resistant genes in AT/RT-CD133{sup +}, and further facilitate to the differentiation of CD133{sup +} into CD133{sup -}. In addition, treatment with 150 {mu}M RV could significantly enhance the radiosensitivity and IR-mediated apoptosis in RV-treated ATRT-CD133{sup +/-}. Kaplan-Meier survival analysis indicated that the mean survival rate of mice with ATRT-CD133{sup +} that were treated with IR could be significantly improved when IR was combined with 150 {mu}M RV treatment. Conclusions: AT/RT-CD133{sup +} exhibit CSC properties and are refractory to IR treatment. Our results suggest that RV treatment plays crucial roles in antiproliferative, proapoptotic, and radiosensitizing effects on treated-CD133{sup +/-}; RV may therefore improve the clinical treatment of AT/RT.

  4. Rothmund-Thomson syndrome: two case reports show heterogeneous cutaneous abnormalities, an association with genetically programmed ageing changes, and increased chromosomal radiosensitivity.

    PubMed Central

    Kerr, B; Ashcroft, G S; Scott, D; Horan, M A; Ferguson, M W; Donnai, D

    1996-01-01

    Rothmund-Thomson syndrome is a rare, autosomal recessive disorder associated with characteristic cutaneous changes, sparse hair, juvenile cataracts, short stature, skeletal defects, dystrophic teeth and nails, and hypogonadism. Mental retardation is unusual. An increased incidence of certain malignancies has been reported. Clonal or mosaic chromosome abnormalities and abnormalities in DNA repair mechanisms have been reported in some cases. We report two cases of Rothmund-Thomson syndrome, both with intellectual handicap, associated in one with a previously undescribed histological appearance of involved skin, suggesting that the spectrum of abnormalities is even more heterogeneous than previously presumed. Both cases exhibited chromosomal radiosensitivity of lymphocytes which may be an indication of a DNA repair defect. This is the first report of an association between Rothmund-Thomson syndrome and unique, intrinsic, age related skin changes. Images PMID:8950673

  5. p53, erbB-2 and K-ras gene alterations are rare in spontaneous and plutonium-239-induced canine lung neoplasia

    SciTech Connect

    Tierney, L.A.; Hahn, F.F.; Lechner, J.F.

    1996-02-01

    Inhalation of high-linear energy transfer radiation in the form of radon progeny is a suspected cause of human lung cancer. To gain insight into the types of genetic derangements caused by this type of radiation, lung tumors from beagle dogs exposed to {sup 239}PuO{sub 2} and those arising in animals with no known carcinogen exposure were examined for evidence of aberrations in genes known to be altered in lung tumors. Altered expression of the p53 tumor suppressor gene and proto-oncogene erbB-2 proteins (p185{sup erbB2}) was evaluated by immunohistochemical analysis of 117 tumors representing different histological types in exposed (n = 80) and unexposed (n = 37) animals. Twenty-eight tumors were analyzed for K-ras proto-oncogene mutations by polymerase chain reaction amplification and direct sequencing. Fourteen percent (16/116) of all lung neoplasms showed elevated nuclear accumulation of p53 protein. Regardless of exposure history, adenosquamous and squamous cell cancers comprised 94% of all tumors with p53 abnormalities. Eighteen percent (21/117) of all tumors had evidence of erbB-2 protein overexpression. K-ras mutations were not detected in codons 12, 13 or 61 of tumors from unexposed (n = 9) or plutonium-exposed dogs (n = 19). These data indicate that p53 and K-ras gene abnormalities as a result of missense mutation are infrequent events in spontaneous and {sup 239}PuO{sub 2}-induced lung neoplasia in this colony of beagle dogs. Alternative mechanisms of gene alteration may be involved in canine pulmonary carcinogenesis. 45 refs., 3 figs., 2 tabs.

  6. Higher Levels of c-Met Expression and Phosphorylation Identify Cell Lines With Increased Sensitivity to AMG-458, a Novel Selective c-Met Inhibitor With Radiosensitizing Effects

    SciTech Connect

    Li Bo; Torossian, Artour; Sun, Yunguang; Du, Ruihong; Dicker, Adam P.; Lu Bo

    2012-11-15

    Purpose: c-Met is overexpressed in some non-small cell lung cancer (NSCLC) cell lines and tissues. Cell lines with higher levels of c-Met expression and phosphorylation depend on this receptor for survival. We studied the effects of AMG-458 on 2 NSCLC cell lines. Methods and Materials: 3-(4,5-Dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl) -2H-tetrazolium assays assessed the sensitivities of the cells to AMG-458. Clonogenic survival assays illustrated the radiosensitizing effects of AMG-458. Western blot for cleaved caspase 3 measured apoptosis. Immunoblotting for c-Met, phospho-Met (p-Met), Akt/p-Akt, and Erk/p-Erk was performed to observe downstream signaling. Results: AMG-458 enhanced radiosensitivity in H441 but not in A549. H441 showed constitutive phosphorylation of c-Met. A549 expressed low levels of c-Met, which were phosphorylated only in the presence of exogenous hepatocyte growth factor. The combination of radiation therapy and AMG-458 treatment was found to synergistically increase apoptosis in the H441 cell line but not in A549. Radiation therapy, AMG-458, and combination treatment were found to reduce p-Akt and p-Erk levels in H441 but not in A549. H441 became less sensitive to AMG-458 after small interfering RNA knockdown of c-Met; there was no change in A549. After overexpression of c-Met, A549 became more sensitive, while H441 became less sensitive to AMG-458. Conclusions: AMG-458 was more effective in cells that expressed higher levels of c-Met/p-Met, suggesting that higher levels of c-Met and p-Met in NSCLC tissue may classify a subset of tumors that are more sensitive to molecular therapies against this receptor.

  7. Radiosensitive severe combined immunodeficiency disease.

    PubMed

    Dvorak, Christopher C; Cowan, Morton J

    2010-02-01

    Inherited defects in components of the nonhomologous end-joining DNA repair mechanism produce a T-B-NK+ severe combined immunodeficiency disease (SCID) characterized by heightened sensitivity to ionizing radiation. Patients with the radiosensitive form of SCID may also have increased short- and long-term sensitivity to the alkylator-based chemotherapy regimens that are traditionally used for conditioning before allogeneic hematopoietic cell transplantation (HCT). Known causes of radiosensitive SCID include deficiencies of Artemis, DNA ligase IV, DNA-dependent protein kinase catalytic subunit, and Cernunnos-XLF, all of which have been treated with HCT. Because of these patients' sensitivity to certain forms of chemotherapy, the approach to donor selection and the type of conditioning regimen used for a patient with radiosensitive SCID requires careful consideration. Significantly more research needs to be done to determine the long-term outcomes of patients with radiosensitive SCID after HCT and to discover novel nontoxic approaches to HCT that might benefit those patients with intrinsic radiosensitivity and chemosensitivity as well as potentially all patients undergoing an HCT. PMID:20113890

  8. Sulforaphane, quercetin and catechins complement each other in elimination of advanced pancreatic cancer by miR-let-7 induction and K-ras inhibition

    PubMed Central

    APPARI, MAHESH; BABU, KAMESH R.; KACZOROWSKI, ADAM; GROSS, WOLFGANG; HERR, INGRID

    2014-01-01

    Pancreatic ductal adenocarcinoma (PDA) has the worst prognosis of all malignancies, and current therapeutic options do not target cancer stem cells (CSCs), which may be the reason for the extreme aggressiveness. The dietary agents sulforaphane and quercetin enriched e.g., in broccoli, and the main and best studied green tea catechin EGCG hold promise as anti-CSC agents in PDA. We examined the efficacy of additional catechins and the combination of these bioactive agents to stem cell features and miRNA signaling. Two established and one primary PDA cell line and non-malignant pancreatic ductal cells were used. Whereas each agent strongly inhibited colony formation, the catechins ECG and CG were more effective than EGCG. A mixture of green tea catechins (GTCs) significantly inhibited viability, migration, expression of MMP-2 and -9, ALDH1 activity, colony and spheroid formation and induced apoptosis, but the combination of GTCs with sulforaphane or quercetin was superior. Following treatment with bioactive agents, the expression of miR-let7-a was specifically induced in cancer cells but not in normal cells and it was associated with K-ras inhibition. These data demonstrate that sulforaphane, quercetin and GTC complement each other in inhibition of PDA progression by induction of miR-let7-a and inhibition of K-ras. PMID:25017900

  9. ¹H, ¹³C and ¹⁵N resonance assignment for the human K-Ras at physiological pH.

    PubMed

    Vo, Uybach; Embrey, Kevin J; Breeze, Alexander L; Golovanov, Alexander P

    2013-10-01

    K-Ras, a member of the Ras family of small GTPases, is involved in cell growth, proliferation, differentiation and apoptosis and is frequently mutated in cancer. The activity of Ras is mediated by the inter-conversion between GTP- and GDP- bound states. This conversion is regulated by binding of effector proteins such as guanine nucleotide exchange factors and GTPase activating proteins. Previously, NMR signals from these effector-binding regions of Ras often remained unassigned and largely unobservable due to conformational exchange and polysterism inherent to this protein. In this paper, we report the complete backbone and C(β), as well as partial H(α), H(β) and C(γ), NMR assignment for human K-Ras (residues 1-166) in the GDP-bound form at a physiological pH of 7.4. These data thereby make possible detailed monitoring of the functional cycle of Ras and its interactions with nucleotides and effector proteins through the observation of fingerprint signals from all the functionally important regions of the protein. PMID:22886485

  10. Neutron radiation can activate K-ras via a point mutation in codon 146 and induces a different spectrum of ras mutations than does gamma radiation.

    PubMed Central

    Sloan, S R; Newcomb, E W; Pellicer, A

    1990-01-01

    Neutron radiation is known to produce tumors in animals and cause cell transformation. We have developed a protocol to efficiently induce thymic lymphomas in RF/J mice by a single acute dose of neutron irradiation. Activated ras genes were detected in 17% (4 of 24) of the tumors analyzed. One of the tumors contained a K-ras gene activated by a point mutation in codon 146. Activating ras mutations at position 146 have not been previously detected in any known human or animal tumors. The spectrum of ras mutations detected in neutron radiation-induced thymic lymphomas was different from that seen in thymic lymphomas induced by gamma radiation in the same strain of mice. These results may have important implications for the mechanisms by which different types of radiation damage DNA. Images PMID:2403644

  11. MGMT promoter hypermethylation and K-RAS, PTEN and TP53 mutations in tamoxifen-exposed and non-exposed endometrial cancer cases

    PubMed Central

    Nagy, E; Gajjar, K B; Patel, I I; Taylor, S; Martin-Hirsch, P L; Stringfellow, H F; Martin, F L; Phillips, D H

    2014-01-01

    Background: Tamoxifen has anti-oestrogenic and anti-tumour activity in the breast, but is oestrogenic and carcinogenic in the endometrium. It can induce experimental tumours by both hormonal and DNA-damaging mechanisms, but its carcinogenic mode of action in human endometrium remains unclear. Methods: We investigated whether an epigenetic mechanism, involving promoter hypermethylation of the gene for the DNA repair enzyme MGMT (O6-methylguanine DNA methyltransferase), was associated with K-RAS, TP53 and PTEN mutations in endometrial tumours from women treated with tamoxifen (TAM, n=30) or unexposed to the drug (EC, n=38). Results: There were significant (P<0.05) differences in tumour grade between the TAM and EC groups, with more favourable morphology in the latter. K-RAS mutations, predominantly G>A, occurred in small numbers in both groups. TP53 mutations were of mainly A>G, C>T and indel modifications in both groups, but more frequent in TAM cases. PTEN mutations dominated in EC tumours and were of the type that has large impact on protein function, such as indel or nonsense mutations. These observations alongside the mutational spectrum in PTEN suggest that the malignancies arise from different backgrounds, hence pointing to an effect of tamoxifen. Both groups displayed MGMT promoter hypermethylation. This coincided with mutations more frequently in the TAM (78%) than in the EC (50%) group, even though there were significantly (P<0.05) fewer mutations and methylations in TAM cases. Conclusions: Although the difference in coincidence did not reach significance with the current sample size, the findings suggest that epigenetic processes may play a role in the way tamoxifen induces endometrial cancer. PMID:24853176

  12. Radiosensitive Severe Combined Immunodeficiency Disease

    PubMed Central

    Dvorak, Christopher C.; Cowan, Morton J.

    2009-01-01

    Synopsis Inherited defects in components of the non-homologous end joining DNA repair mechanism produce a T-B-NK+ severe combined immunodeficiency disease (SCID) characterized by heightened sensitivity to ionizing radiation. Patients with the radiosensitive form of SCID may also have increased short- and long-term sensitivity to the alkylator-based chemotherapy regimens traditionally utilized for conditioning prior to allogeneic hematopoietic cell transplantation (HCT). Known etiologies of radiosensitive SCID include deficiencies of Artemis, DNA Ligase IV, DNA-dependent protein kinase catalytic subunit (DNA-PKcs), and Cernunnos-XLF, all of which have been treated with HCT. Because of their sensitivity to certain forms of chemotherapy, the approach to donor selection and type of conditioning regimen utilized for a radiosensitive SCID patient requires careful consideration. Significantly more research needs to be done in order to determine the long-term outcomes of radiosensitive SCID patients following HCT, as well as to discover novel non-toxic approaches to HCT that might benefit those with intrinsic radio- and chemo-sensitivity, as well as potentially all patients undergoing an HCT. PMID:20113890

  13. Extracting the normal lung dose-response curve from clinical DVH data: a possible role for low dose hyper-radiosensitivity, increased radioresistance

    NASA Astrophysics Data System (ADS)

    Gordon, J. J.; Snyder, K.; Zhong, H.; Barton, K.; Sun, Z.; Chetty, I. J.; Matuszak, M.; Ten Haken, R. K.

    2015-09-01

    In conventionally fractionated radiation therapy for lung cancer, radiation pneumonitis’ (RP) dependence on the normal lung dose-volume histogram (DVH) is not well understood. Complication models alternatively make RP a function of a summary statistic, such as mean lung dose (MLD). This work searches over damage profiles, which quantify sub-volume damage as a function of dose. Profiles that achieve best RP predictive accuracy on a clinical dataset are hypothesized to approximate DVH dependence. Step function damage rate profiles R(D) are generated, having discrete steps at several dose points. A range of profiles is sampled by varying the step heights and dose point locations. Normal lung damage is the integral of R(D) with the cumulative DVH. Each profile is used in conjunction with a damage cutoff to predict grade 2 plus (G2+) RP for DVHs from a University of Michigan clinical trial dataset consisting of 89 CFRT patients, of which 17 were diagnosed with G2+ RP. Optimal profiles achieve a modest increase in predictive accuracy—erroneous RP predictions are reduced from 11 (using MLD) to 8. A novel result is that optimal profiles have a similar distinctive shape: enhanced damage contribution from low doses (<20 Gy), a flat contribution from doses in the range ~20-40 Gy, then a further enhanced contribution from doses above 40 Gy. These features resemble the hyper-radiosensitivity / increased radioresistance (HRS/IRR) observed in some cell survival curves, which can be modeled using Joiner’s induced repair model. A novel search strategy is employed, which has the potential to estimate RP dependence on the normal lung DVH. When applied to a clinical dataset, identified profiles share a characteristic shape, which resembles HRS/IRR. This suggests that normal lung may have enhanced sensitivity to low doses, and that this sensitivity can affect RP risk.

  14. Lack of DNA polymerase theta (POLQ) radiosensitizes bone marrow stromal cells in vitro and increases reticulocyte micronuclei after total-body irradiation.

    PubMed

    Goff, Julie P; Shields, Donna S; Seki, Mineaki; Choi, Serah; Epperly, Michael W; Dixon, Tracy; Wang, Hong; Bakkenist, Christopher J; Dertinger, Stephen D; Torous, Dorothea K; Wittschieben, John; Wood, Richard D; Greenberger, Joel S

    2009-08-01

    Abstract Mammalian POLQ (pol theta) is a specialized DNA polymerase with an unknown function in vivo. Roles have been proposed in chromosome stability, as a backup enzyme in DNA base excision repair, and in somatic hypermutation of immunoglobulin genes. The purified enzyme can bypass AP sites and thymine glycol. Mice defective in POLQ are viable and have been reported to have elevated spontaneous and radiation-induced frequencies of micronuclei in circulating red blood cells. To examine the potential roles of POLQ in hematopoiesis and in responses to oxidative stress responses, including ionizing radiation, bone marrow cultures and marrow stromal cell lines were established from Polq(+/+) and Polq(-/-) mice. Aging of bone marrow cultures was not altered, but Polq(-/-) cells were more sensitive to gamma radiation than were Polq(+/+) cells. The D(0) was 1.38 +/- 0.06 Gy for Polq(+/+) cells compared to 1.27 +/- 0.16 and 0.98 +/- 0.10 Gy (P = 0.032) for two Polq(-/-) clones. Polq(-/-) cells were moderately more sensitive to bleomycin than Polq(+/+) cells and were not hypersensitive to paraquat or hydrogen peroxide. ATM kinase activation appeared to be normal in gamma-irradiated Polq(-/-) cells. Inhibition of ATM kinase activity increased the radiosensitivity of Polq(+/+) cells slightly but did not affect Polq(-/-) cells. Polq(-/-) mice had more spontaneous and radiation-induced micronucleated reticulocytes than Polq+/+ and (+/-) mice. The sensitivity of POLQ-defective bone marrow stromal cells to ionizing radiation and bleomycin and the increase in micronuclei in red blood cells support a role for this DNA polymerase in cellular tolerance of DNA damage that can lead to double-strand DNA breaks. PMID:19630521

  15. Transition in Survival From Low-Dose Hyper-Radiosensitivity to Increased Radioresistance Is Independent of Activation of ATM SER1981 Activity

    SciTech Connect

    Krueger, Sarah A.; Collis, Spencer J.; Joiner, Michael C.; Wilson, George D.; Marples, Brian

    2007-11-15

    Purpose: The molecular basis of low-dose hyper-radiosensitivity (HRS) is only partially understood. The aim of this study was to define the roles of ataxia telangiectasia mutated (ATM) activity and the downstream ATM-dependent G{sub 2}-phase cell cycle checkpoint in overcoming HRS and triggering radiation resistance. Methods and Materials: Survival was measured using a high-resolution clonogenic assay. ATM Ser1981 activation was measured by Western blotting. The role of ATM was determined in survival experiments after molecular (siRNA) and chemical (0.4 mM caffeine) inhibition and chemical (20 {mu}g/mL chloroquine, 15 {mu}M genistein) activation 4-6 h before irradiation. Checkpoint responsiveness was assessed in eight cell lines of differing HRS status using flow cytometry to quantify the progression of irradiated (0-2 Gy) G{sub 2}-phase cells entering mitosis, using histone H3 phosphorylation analysis. Results: The dose-response pattern of ATM activation was concordant with the transition from HRS to radioresistance. However, ATM activation did not play a primary role in initiating increased radioresistance. Rather, a relationship was discovered between the function of the downstream ATM-dependent early G{sub 2}-phase checkpoint and the prevalence and overcoming of HRS. Four cell lines that exhibited HRS failed to show low-dose (<0.3-Gy) checkpoint function. In contrast, four HRS-negative cell lines exhibited immediate cell cycle arrest for the entire 0-2-Gy dose range. Conclusion: Overcoming HRS is reliant on the function of the early G{sub 2}-phase checkpoint. These data suggest that clinical exploitation of HRS could be achieved by combining radiotherapy with chemotherapeutic agents that modulate this cell cycle checkpoint.

  16. [Synthesis and radiosensitizing activity of benzimidazoles].

    PubMed

    Li, M J; Li, S Z; Zhuang, X L; Chen, A; Zhang, H Q; Pang, X C; Hu, B

    1992-01-01

    In search for effective radiosensitizer with low neurotoxicity, benzimidazole compounds were synthesized. Reaction of 2-nitrobenzimidazole with ethyl chloroformate yielded ethyl alpha-(2-nitrobenzimidazolyl-1)-formate(1) or ethyl alpha-(2-hydroxybenzimidazolyl-1)-formate(2), depending upon the solvents used. Reaction of 2-nitrobenzimidazole with 1,2-epoxy-3-chloropropane gave a cyclized compound which was confirmed to be benzimidazo(1,2b)-5'-chloromethyl-oxazolidine(3). In attempt to increase hydrophilicity, 1-substituted 2(3'-pyridyl)-5-nitrobenzimidazoles were prepared by reaction of 2-(3'-pyridyl)-5(6)-nitrobenzimidazole(4) with alkyl epoxides or ethyl chloroacetate. Some of the compounds synthesized were tested for radiosensitizing activity in Ehrlich ascites carcinoma-bearing mice. Preliminary results showed that some compounds have radiosensitizing activity. The radiosensitizing enhancement ratio (SER) of compounds 3, 5 and 6 were found to be 1.50, 1.52 and 1.65 respectively. PMID:1293936

  17. Daily rhythms of radiosensitivity of animals and several determining causes

    NASA Technical Reports Server (NTRS)

    Druzhinin, Y. P.; Malyutina, T. S.; Seraya, V. M.; Rodina, G. P.; Vatsek, A.; Rakova, A.

    1974-01-01

    Daily rhythms of radiosensitivity in rats and mice were determined by survival rates after acute total radiation at the same dosage at different times of the day. Radiosensitivity differed in animals of different species and varieties. Inbred mice exhibited one or two increases in radiosensitivity during the dark, active period of the day. These effects were attributed to periodic changes in the state of stem hematopoietic cells.

  18. Non-covalent interactions of the carcinogen (+)-anti-BPDE with exon 1 of the human K-ras proto-oncogene

    NASA Astrophysics Data System (ADS)

    Rodriguez, Jorge H.; Deligkaris, Christos

    2013-03-01

    Investigating the complementary, but different, effects of physical (non-covalent) and chemical (covalent) mutagen-DNA and carcinogen-DNA interactions is important for understanding possible mechanisms of development and prevention of mutagenesis and carcinogenesis. A highly mutagenic and carcinogenic metabolite of the polycyclic aromatic hydrocarbon benzo[ α]pyrene, namely (+)-anti-BPDE, is known to undergo both physical and chemical complexation with DNA. The major covalent adduct, a promutagenic, is known to be an external (+)-trans-anti-BPDE-N2-dGuanosine configuration whose origins are not fully understood. Thus, it is desirable to study the mechanisms of external non-covalent BPDE-DNA binding and their possible relationships to external covalent trans adduct formation. We present a detailed codon-by-codon computational study of the non-covalent interactions of (+)-anti-BPDE with DNA which explains and correctly predicts preferential (+)-anti-BPDE binding at minor groove guanosines. Due to its relevance to carcinogenesis, the interaction of (+)-anti-BPDE with exon 1 of the human K-ras gene has been studied in detail. Present address: Department of Physics, Drury University

  19. Novel Ras pathway inhibitor induces apoptosis and growth inhibition of K-ras-mutated cancer cells in vitro and in vivo.

    PubMed

    Jasinski, Piotr; Zwolak, Pawel; Terai, Kaoru; Dudek, Arkadiusz Z

    2008-11-01

    MT477 is a novel quinoline with potential activity in Ras-mutated cancers. In this study, MT477 preferentially inhibited the proliferation of K-ras-mutated human pulmonary (A549) and pancreatic (MiaPaCa-2) adenocarcinoma cell lines, compared with a non-Ras-mutated human lung squamous carcinoma cell line (H226) and normal human lung fibroblasts. MT477 treatment induced apoptosis in A549 cells and was associated with caspase-3 activation. MT477 also induced sub-G1 cell-cycle arrest in A549 cells. Although we found that MT477 partially inhibited protein kinase C (PKC), it inhibited Ras directly followed in time by inhibition of 2 Ras downstream molecules, Erk1/2 and Ral. MT477 also caused a reorganization of the actin cytoskeleton and formation of filopodias in A549 cells; this event may lead to decreased migration and invasion of tumor cells. In a xenograft mouse model, A549 tumor growth was inhibited significantly by MT477 at a dose of 1 mg/kg (P < 0.05 vs vehicle control). Taken together, these results support the conclusion that MT477 acts as a direct Ras inhibitor. This quinoline, therefore, could potentially be active in Ras-mutated cancers and could be developed extensively as an anticancer molecule with this in mind. PMID:19010291

  20. A vertically-stacked, polymer, microfluidic point mutation analyzer: Rapid, high accuracy detection of low-abundance K-ras mutations

    PubMed Central

    Han, Kyudong; Lee, Tae Yoon; Nikitopoulos, Dimitris E.; Soper, Steven A.; Murphy, Michael C.

    2011-01-01

    Recognition of point mutations in the K-ras gene can be used for the clinical management of several types of cancers. Unfortunately, several assay and hardware concerns must be addressed to allow users not well-trained in performing molecular analyses the opportunity to undertake these measurements. To provide for a larger user-base for these types of molecular assays, a vertically-stacked microfluidic analyzer with a modular architecture and process automation was developed. The analyzer employed a primary PCR coupled to an allele-specific ligase detection reaction (LDR). Each functional device, including continuous flow thermal reactors for the PCR and LDR, passive micromixers and ExoSAP-IT® purification, was designed and tested. Individual devices were fabricated in polycarbonate using hot embossing and assembled using adhesive bonding for system assembly. The system produced LDR products from a DNA sample in ~1 h, an 80% reduction in time compared to conventional bench-top instrumentation. Purifying the post-PCR products with the ExoSAP-IT® enzyme led to optimized LDR performance minimizing false positive signals and producing reliable results. Mutant alleles in genomic DNA were quantified to the level of 0.25 ng of mutant DNA in 50 ng of wild-type DNA for a 25 μL sample, equivalent to DNA from 42 mutant cells. PMID:21771577

  1. Predictive value of K-ras and PIK3CA in non-small cell lung cancer patients treated with EGFR-TKIs: a systemic review and meta-analysis

    PubMed Central

    Chen, Jie-Ying; Cheng, Ya-Nan; Han, Lei; Wei, Feng; Yu, Wen-Wen; Zhang, Xin-Wei; Cao, Shui; Yu, Jin-Pu

    2015-01-01

    Objective A meta-analysis was performed to augment the insufficient data on the impact of mutative EGFR downstream phosphatidylinositol-3-kinase (PI3K) and mitogen-activated protein kinase (MAPK) pathways on the clinical efficiency of epidermal growth factor receptor tyrosine kinase inhibitor (EGFR-TKI) treatment of non-small cell lung cancer (NSCLC) patients. Methods Network databases were explored in April, 2015. Papers that investigated the clinical outcomes of NSCLC patients treated with EGFR-TKIs according to the status of K-ras and/or PIK3CA gene mutation were included. A quantitative meta-analysis was conducted using standard statistical methods. Odds ratios (ORs) for objective response rate (ORR) and hazard ratios (HRs) for progression-free survival (PFS) and overall survival (OS) were calculated. Results Mutation in K-ras significantly predicted poor ORR [OR =0.22; 95% confidence interval (CI), 0.13-0.35], shorter PFS (HR =1.56; 95% CI, 1.27-1.92), and shorter OS (HR =1.59; 95% CI, 1.33-1.91) in NSCLC patients treated with EGFR-TKIs. Mutant PIK3CA significantly predicted shorter OS (HR =1.83; 95% CI, 1.05-3.20), showed poor ORR (OR =0.70; 95% CI, 0.22-2.18), and shorter PFS (HR =1.79; 95% CI, 0.91-3.53) in NSCLC patients treated with EGFR-TKIs. Conclusion K-ras mutation adversely affected the clinical response and survival of NSCLC patients treated with EGFR-TKIs. PIK3CA mutation showed similar trends. In addition to EGFR, adding K-ras and PIK3CA as routine gene biomarkers in clinical genetic analysis is valuable to optimize the effectiveness of EGFR-TKI regimens and identify optimal patients who will benefit from EGFR-TKI treatment. PMID:26175928

  2. Preventive effects of butyric acid, nicotinamide, calcium glucarate alone or in combination during the 7, 12-dimethylbenz (a) anthracene induced mouse skin tumorigenesis via modulation of K-Ras-PI3K-AKTpathway and associated micro RNAs.

    PubMed

    Tiwari, Prakash; Sahay, Satya; Pandey, Manuraj; Qadri, Syed S Y H; Gupta, Krishna P

    2016-02-01

    Skin cancer is among the most common cancers worldwide and identifiable molecular changes for early and late stage of skin tumorigenesis can suggest the better targets for its control. In this study, we investigated the status of K-Ras-PI3K-AKTpathway followed by NF-κB, cyclin D1, MMP-9 and regulatory micro RNA during 7, 12-dimethylbenz[a]anthracene (DMBA) induced mouse skin tumorigenesis and its prevention by butyric acid (BA), nicotinamide (NA) and calcium glucarate (CAG), individually or in combination with respect to time. DMBA upregulated the K-Ras, PI3K, Akt, NF-κB, cyclin D1 and MMP-9, but downregulated the PTEN in a time dependent manner. DMBA also reduced the levels of micoRNA let-7a but induced the levels of miR-21 and miR-20a as a function of time. BA, NA and CAG were found to prevent DMBA induced changes, but they were most effective when used together in a combination. Reduced let-7a and miR-211 were correlated with the overexpression of K-Ras and MMP-9. Overexpression of miR-21 and miR-20a was correlated with the down regulation of PTEN and overexpression of Cyclin D1. Collectively, the enhanced chemopreventive potential of natural compound in combination via regulation of K-Ras-PI3K-AKTpathway along with regulatory micro RNAs provide a newer and effective mean for cancer management. PMID:26655363

  3. On the radiosensitivity of man in space

    NASA Astrophysics Data System (ADS)

    Esposito, R. D.; Durante, M.; Gialanella, G.; Grossi, G.; Pugliese, M.; Scampoli, P.; Jones, T. D.

    Astronauts' radiation exposure limits are based on experimental and epidemiological data obtained on Earth. It is assumed that radiation sensitivity remains the same in the extraterrestrial space. However, human radiosensitivity is dependent upon the response of the hematopoietic tissue to the radiation insult. It is well known that the immune system is affected by microgravity. We have developed a mathematical model of radiation-induced myelopoiesis which includes the effect of microgravity on bone marrow kinetics. It is assumed that cellular radiosensitivity is not modified by the space environment, but repopulation rates of stem and stromal cells are reduced as a function of time in weightlessness. A realistic model of the space radiation environment, including the HZE component, is used to simulate the radiation damage. A dedicated computer code was written and applied to solar particle events and to the mission to Mars. The results suggest that altered myelopoiesis and lymphopoiesis in microgravity might increase human radiosensitivity in space.

  4. Pharmacological Ascorbate Radiosensitizes Pancreatic Cancer.

    PubMed

    Du, Juan; Cieslak, John A; Welsh, Jessemae L; Sibenaller, Zita A; Allen, Bryan G; Wagner, Brett A; Kalen, Amanda L; Doskey, Claire M; Strother, Robert K; Button, Anna M; Mott, Sarah L; Smith, Brian; Tsai, Susan; Mezhir, James; Goswami, Prabhat C; Spitz, Douglas R; Buettner, Garry R; Cullen, Joseph J

    2015-08-15

    The toxicity of pharmacologic ascorbate is mediated by the generation of H2O2 via the oxidation of ascorbate. Because pancreatic cancer cells are sensitive to H2O2 generated by ascorbate, they would also be expected to become sensitized to agents that increase oxidative damage such as ionizing radiation. The current study demonstrates that pharmacologic ascorbate enhances the cytotoxic effects of ionizing radiation as seen by decreased cell viability and clonogenic survival in all pancreatic cancer cell lines examined, but not in nontumorigenic pancreatic ductal epithelial cells. Ascorbate radiosensitization was associated with an increase in oxidative stress-induced DNA damage, which was reversed by catalase. In mice with established heterotopic and orthotopic pancreatic tumor xenografts, pharmacologic ascorbate combined with ionizing radiation decreased tumor growth and increased survival, without damaging the gastrointestinal tract or increasing systemic changes in parameters indicative of oxidative stress. Our results demonstrate the potential clinical utility of pharmacologic ascorbate as a radiosensitizer in the treatment of pancreatic cancer. PMID:26081808

  5. Pharmacological Ascorbate Radiosensitizes Pancreatic Cancer

    PubMed Central

    Du, Juan; Cieslak, John A.; Welsh, Jessemae L.; Sibenaller, Zita A.; Allen, Bryan G.; Wagner, Brett A.; Kalen, Amanda L.; Doskey, Claire M.; Strother, Robert K.; Button, Anna M.; Mott, Sarah L.; Smith, Brian; Tsai, Susan; Mezhir, James; Goswami, Prabhat C.; Spitz, Douglas R.; Buettner, Garry R.; Cullen, Joseph J.

    2015-01-01

    The toxicity of pharmacological ascorbate is mediated by the generation of H2O2 via the oxidation of ascorbate. Since pancreatic cancer cells are sensitive to H2O2 generated by ascorbate they would also be expected to become sensitized to agents that increase oxidative damage such as ionizing radiation. The current study demonstrates that pharmacological ascorbate enhances the cytotoxic effects of ionizing radiation as seen by decreased cell viability and clonogenic survival in all pancreatic cancer cell lines examined, but not in non-tumorigenic pancreatic ductal epithelial cells. Ascorbate radiosensitization was associated with an increase in oxidative stress-induced DNA damage, which was reversed by catalase. In mice with established heterotopic and orthotopic pancreatic tumor xenografts, pharmacological ascorbate combined with ionizing radiation decreased tumor growth and increased survival, without damaging the gastrointestinal tract or increasing systemic changes in parameters indicative of oxidative stress. Our results demonstrate the potential clinical utility of pharmacological ascorbate as a radiosensitizer in the treatment of pancreatic cancer. PMID:26081808

  6. Azidothymidine Enhances Fluorodeoxyuridine-Mediated Radiosensitization

    SciTech Connect

    Chen, C.-M.; Johnson, Monika; Smith, Brian J.; Dornfeld, Ken

    2010-03-01

    Purpose: To examine the role of DNA repair and altered thymidine analogues in altering the response to radiation during thymidine deprivation. Methods and Materials: Mismatch repair-deficient and -proficient cell lines HEC59 and HC-2.4 were treated with fluorodeoxyuridine (FUdR), azidothymidine (AZT), and irradiation either alone or in combination, and outcomes of clonogenic survival and cell-cycle distributions were determined. Results: Survival outcomes for all treatments were similar for both cell lines, suggesting that hMSH2 does not significantly influence thymidine deprivation toxicity or radiosensitization. The chain-terminating thymidine analogue AZT increased the toxicity of FUdR and increased DNA fragmentation. The combination of FUdR and AZT afforded greater radiosensitization than either drug alone. Drug enhancement ratios, the degree of excess radiation-induced cell death in drug-treated cultures compared with radiation alone for HEC59, were 1.2, 1.4, and 1.8 for AZT, FUdR, and the combination, respectively. Enhancement ratios for HC-2.4 were 1.3, 1.5, and 1.8 for AZT, FUdR, and the combination, respectively. Conclusion: Azidothymidine, a chain-terminating thymidine analogue, can enhance the radiosensitizing affects of thymidine deprivation. Deoxyribonucleic acid strand breaks may play an important role in the mechanism of thymidine deprivation-induced radiosensitization.

  7. Recent developments in radiosensitization.

    PubMed

    Linam, Justin; Yang, Li-Xi

    2015-05-01

    Radiation therapy is essential for local tumor control for many types of cancer histologies. Technological advancements in recent years have allowed for precise irradiation of target tissues while minimizing the dose to non-target tissues. To enhance radiation damage to cancer cells and further limit the radiation effects on normal tissue, researchers have explored compounds that specifically target cancer cells and make them more sensitive to ionizing radiation. Recent radiosensitization research has focused on promising compounds that alter hypoxia, inhibit topoisomerases, interfere with microtubules, and activate caspases, among other mechanisms. Many such compounds have shown impressive results in pre-clinical trials against a variety of cell types, but their safety, efficacy and practicability in clinical trials remains to be demonstrated. This review seeks to provide an overview of recent research in radiosensitization, detailing some of the more successful compounds, and illustrating avenues for future research. PMID:25964520

  8. Cdc42 and k-Ras Control Endothelial Tubulogenesis through Apical Membrane and Cytoskeletal Polarization: Novel Stimulatory Roles for GTPase Effectors, the Small GTPases, Rac2 and Rap1b, and Inhibitory Influence of Arhgap31 and Rasa1.

    PubMed

    Norden, Pieter R; Kim, Dae Joong; Barry, David M; Cleaver, Ondine B; Davis, George E

    2016-01-01

    A critical and understudied property of endothelial cells is their ability to form lumens and tube networks. Although considerable information has been obtained concerning these issues, including the role of Cdc42 and Rac1 and their effectors such as Pak2, Pak4, Par6b, and co-regulators such as integrins, MT1-MMP and Par3; many key questions remain that are necessary to elucidate molecular and signaling requirements for this fundamental process. In this work, we identify new small GTPase regulators of EC tubulogenesis including k-Ras, Rac2 and Rap1b that act in conjunction with Cdc42 as well as the key downstream effectors, IQGAP1, MRCKβ, beta-Pix, GIT1, and Rasip1 (which can assemble into multiprotein complexes with key regulators including α2β1 integrin and MT1-MMP). In addition, we identify the negative regulators, Arhgap31 (by inactivating Cdc42 and Rac) and Rasa1 (by inactivating k-Ras) and the positive regulator, Arhgap29 (by inactivating RhoA) which play a major functional role during the EC tubulogenic process. Human EC siRNA suppression or mouse knockout of Rasip1 leads to identical phenotypes where ECs form extensive cord networks, but cannot generate lumens or tubes. Essential roles for these molecules during EC tubulogenesis include; i) establishment of asymmetric EC cytoskeletal polarization (subapical distribution of acetylated tubulin and basal membrane distribution of F-actin); and ii) directed membrane trafficking of pinocytic vacuoles or other intracellular vesicles along acetylated tubulin tracks to the developing apical membrane surface. Cdc42 co-localizes subapically with acetylated tubulin, while Rac1 and k-Ras strongly label vacuole/ vesicle membranes which accumulate and fuse together in a polarized, perinuclear manner. We observe polarized apical membrane and subapical accumulation of key GTPases and effectors regulating EC lumen formation including Cdc42, Rac1, Rac2, k-Ras, Rap1b, activated c-Raf and Rasip1 to control EC tube network

  9. Cdc42 and k-Ras Control Endothelial Tubulogenesis through Apical Membrane and Cytoskeletal Polarization: Novel Stimulatory Roles for GTPase Effectors, the Small GTPases, Rac2 and Rap1b, and Inhibitory Influence of Arhgap31 and Rasa1

    PubMed Central

    Norden, Pieter R.; Kim, Dae Joong; Barry, David M.; Cleaver, Ondine B.; Davis, George E.

    2016-01-01

    A critical and understudied property of endothelial cells is their ability to form lumens and tube networks. Although considerable information has been obtained concerning these issues, including the role of Cdc42 and Rac1 and their effectors such as Pak2, Pak4, Par6b, and co-regulators such as integrins, MT1-MMP and Par3; many key questions remain that are necessary to elucidate molecular and signaling requirements for this fundamental process. In this work, we identify new small GTPase regulators of EC tubulogenesis including k-Ras, Rac2 and Rap1b that act in conjunction with Cdc42 as well as the key downstream effectors, IQGAP1, MRCKβ, beta-Pix, GIT1, and Rasip1 (which can assemble into multiprotein complexes with key regulators including α2β1 integrin and MT1-MMP). In addition, we identify the negative regulators, Arhgap31 (by inactivating Cdc42 and Rac) and Rasa1 (by inactivating k-Ras) and the positive regulator, Arhgap29 (by inactivating RhoA) which play a major functional role during the EC tubulogenic process. Human EC siRNA suppression or mouse knockout of Rasip1 leads to identical phenotypes where ECs form extensive cord networks, but cannot generate lumens or tubes. Essential roles for these molecules during EC tubulogenesis include; i) establishment of asymmetric EC cytoskeletal polarization (subapical distribution of acetylated tubulin and basal membrane distribution of F-actin); and ii) directed membrane trafficking of pinocytic vacuoles or other intracellular vesicles along acetylated tubulin tracks to the developing apical membrane surface. Cdc42 co-localizes subapically with acetylated tubulin, while Rac1 and k-Ras strongly label vacuole/ vesicle membranes which accumulate and fuse together in a polarized, perinuclear manner. We observe polarized apical membrane and subapical accumulation of key GTPases and effectors regulating EC lumen formation including Cdc42, Rac1, Rac2, k-Ras, Rap1b, activated c-Raf and Rasip1 to control EC tube network

  10. Change in radiosensitivity of rats during hypokinetic stress

    NASA Technical Reports Server (NTRS)

    Chernov, I. P.

    1980-01-01

    The laws governing stress modification of radiation sickness in relation to hypokinetic stress were investigated. It was found that gamma irradiation (800 rad) of rats on the third day of exposure to hypokinesia increased the radiosensitivity of the animals which was determined by the survival rate and the dynamics of body weight and the weight of some internal organs. The same radiation dose was given on the 20th day of hypokinesia and on the third day of recovery from the 20 day hypokinesia decreased the radiosensitivity of rats. It is concluded that the variations in the radiosensitivity observed may be due to a stress effect of hypokinesia.

  11. Radiosensitization of mouse skin by oxygen and depletion of glutathione

    SciTech Connect

    Stevens, G.; Joiner, M.; Joiner, B.

    1995-09-30

    To determine the oxygen enhancement ratio (OER) and shape of the oxygen sensitization curve of mouse foot skin, the extent to which glutathione (GSH) depletion radiosensitized skin, and the dependence of such sensitization on the ambient oxygen tension. Carbogen caused the greatest radiosensitization of skin, with a reproducible enhancement of 2.2 relative to the anoxic response. The OER of 2.2 is lower than other reports for mouse skin. This may indicate that the extremes of oxygenation were not produced, although there was no direct evidence for this. Depletion of GSH caused minimal radiosensitization when skin was irradiated under anoxic or well-oxygenated conditions. Radiosensitization by GSH depletion was maximal at intermediate oxygen tensions of 10-21% O{sub 2} in the ambient gas. Increasing the extent of GSH depletion led to increasing radiosensitization, with sensitization enhancement ratios of 1.2 and 1.1, respectively, for extensive and intermediated levels of GSH depletion. In mice exposed to 100% O{sub 2}, a significant component of skin radiosensitivity was due to diffusion of oxygen directly through the skin. Pentobarbitone anesthesia radiosensitized skin in mice exposed to 100% O{sub 2} by a factor of 1.2, but did not further sensitize skin in mice exposed to carbogen. Glutathione levels and the local oxygen tension at the time of irradiation were important determinants of mouse foot skin radiosensitivity. The extent to which GSH levels altered the radiosensitivity of skin was critically dependent on the local oxygen tension. These results have significant implications for potential clinical applications of GSH depletion. 53 refs., 7 figs., 2 tabs.

  12. Caffeic Acid Phenethyl Ester Increases Radiosensitivity of Estrogen Receptor-Positive and -Negative Breast Cancer Cells by Prolonging Radiation-Induced DNA Damage

    PubMed Central

    Khoram, Nastaran Masoudi; Bigdeli, Bahareh; Nikoofar, Alireza

    2016-01-01

    Purpose Breast cancer is an important cause of death among women. The development of radioresistance in breast cancer leads to recurrence after radiotherapy. Caffeic acid phenethyl ester (CAPE), a polyphenolic compound of honeybee propolis, is known to have anticancer properties. In this study, we examined whether CAPE enhanced the radiation sensitivity of MDA-MB-231 (estrogen receptor-negative) and T47D (estrogen receptor-positive) cell lines. Methods The cytotoxic effect of CAPE on MDA-MB-231 and T47D breast cancer cells was evaluated by performing an 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide (MTT) assay. To assess clonogenic ability, MDA-MB-231 and T47D cells were treated with CAPE (1 µM) for 72 hours before irradiation, and then, a colony assay was performed. A comet assay was used to determine the number of DNA strand breaks at four different times. Results CAPE decreased the viability of both cell lines in a dose- and time-dependent manner. In the clonogenic assay, pretreatment of cells with CAPE before irradiation significantly reduced the surviving fraction of MDA-MB-231 cells at doses of 6 and 8 Gy. A reduction in the surviving fraction of T47D cells was observed relative to MDA-MB-231 at lower doses of radiation. Additionally, CAPE maintained radiation-induced DNA damage in T47D cells for a longer period than in MDA-MB-231 cells. Conclusion Our results indicate that CAPE impairs DNA damage repair immediately after irradiation. The induction of radiosensitivity by CAPE in radioresistant breast cancer cells may be caused by prolonged DNA damage. PMID:27066092

  13. Radiosensitization of E. coli B/r by arylhydrazonopropanedinitriles.

    PubMed

    Crump, P W; Bisby, R H; Cundall, R B; Thomas, E W

    1989-04-01

    Several arylhydrazonopropanedinitriles and an arylhydrazonopropane-diethyl ester (derivatives of well-known uncouplers of oxidative phosphorylation) have been studied with respect to their ability to radiosensitize E. coli B/r under oxic and hypoxic conditions. Of the compounds studied, 2-carboxyphenylhydrazono-propanedinitrile and 2-carboxyphenylhydrazonopropanediethylester were found to be the most efficient radiosensitizers under hypoxia, whilst the former compound was also found to provide radiosensitization under oxic conditions. Increased radiosensitization by 4-carboxyphenylhydrazonopropanedinitrile was observed on decreasing the pH of the irradiation incubation medium. The results are discussed with respect to the physicochemical properties of these compounds and their reactivity with thiols, for which data are presented. PMID:2564869

  14. Benzamide and nicotinamide radiosensitizers

    SciTech Connect

    Lee, W.W.; Brown, J.M.; Grange, E.W.; Martinez, A.P.

    1993-06-01

    A method to destroy hypoxic tumor cells in a warmblooded animal is described, which method comprises: (a) administering to said warmblooded animal a compound of the formula: wherein X is O or S; Z is H, OR, SR or NHR in which R is H, hydrocarbyl (1-6C) including cyclic and unsaturated hydrocarbyl, optionally substituted with 1 or 2 substituents selected from the group consisting of halo, hydroxy, epoxy, alkoxy, alkylthio, amino including morpholino, acyloxy and acylamido and their thio analogs, alkylsulfonyl or alkylphosphonyl, carboxy or alkoxycarbonyl, or carbamyl or alkylcarbamyl, and in which R can optionally be interrupted by a single ether (-O-) linkage; or Z os O(CO)R, NH(CO)R, O(SO)R, or O(POR)R in which R is as above defined, in an amount effective to radiosensitize said hypoxic tumor cells, (b) followed by, after a time period to provide maximum radiosensitization, irradiating said tumor cells with a dose of radiation effective to destroy said cells.

  15. Factors Affecting the Radiosensitivity of Hexaploid Wheat to -Irradiation: Radiosensitivity of Hexaploid Wheat (Triticum aestivum L.).

    PubMed

    Han, Bing; Gu, Jiayu; Zhao, Linshu; Guo, Huijun; Xie, Yongdun; Zhao, Shirong; Song, Xiyun; Han, Longzhi; Liu, Luxiang

    2016-01-01

    Understanding the radiosensitivity of plants, an important factor in crop mutation breeding programs, requires a thorough investigation of the factors that contribute to this trait. In this study, we used the highly radiosensitive wheat (Triticum aestivum L.) variety HY1 and J411, a γ-irradiation-insensitive control, which were screened from a natural population, to examine the factors affecting radiosensitivity, including free radical content and total antioxidant capacity, as well as the expression of TaKu70 and TaKu80 (DNA repair-related genes) as measured by real-time PCR. We also investigated the alternative splicing of this gene in the wild-type wheat ecotype by sequence analysis. Free radical contents and total antioxidant capacity significantly increased upon exposure of HY1 wheat to γ-irradiation in a dose-dependent manner. By contrast, in J411, the free radical contents exhibited a similar trend, but the total antioxidant capacity exhibited a downward trend upon increasing γ-irradiation. Additionally, we detected dose-dependent increases in TaKu70 and TaKu80 expression levels in γ-irradiated HY1, while in J411, TaKu70 expression levels increased, followed by a decline. We also detected alternative splicing of TaKu70 mRNA, namely, intron retention, in HY1 but not in J411. Our findings indicate that γ-irradiation induces oxidative stress and DNA damage in hexaploid wheat, resulting in growth retardation of seedlings, and they suggest that TaKu70 may play a causal role in radiosensitivity in HY1. Further studies are required to exploit these factors to improve radiosensitivity in other wheat varieties. PMID:27551965

  16. Interfaces with Tunable Mechanical and Radiosensitizing Properties.

    PubMed

    Berg, Nora G; Pearce, Brady L; Snyder, Patrick J; Rohrbaugh, Nathaniel; Nolan, Michael W; Adhikari, Prajesh; Khan, Saad A; Ivanisevic, Albena

    2016-08-31

    We report the fabrication of a composite containing nanostructured GaOOH and Matrigel with tunable radiosensitizing and stiffness properties. Composite characterization was done with microscopy and rheology. The utility of the interface was tested in vitro using fibroblasts. Cell viability and reactive oxygen species assays quantified the effects of radiation dosages and GaOOH concentrations. Fibroblasts' viability decreased with increasing concentration of GaOOH and composite stiffness. During ionizing radiation experiments the presence of the scintillating GaOOH triggered a different cellular response. Reactive oxygen species data demonstrated that one can reduce the amount of radiation needed to modulate the behavior of cells on interfaces with different stiffness containing a radiosensitizing material. PMID:26882455

  17. Irinotecan and radiosensitization in rectal cancer.

    PubMed

    Illum, Henrik

    2011-04-01

    Neoadjuvant radiation therapy with concurrent 5-fluorouracil-based chemotherapy is currently considered the standard of care for locally advanced rectal cancer. Pathologically complete response is a desirable outcome and has been associated with increased disease-free survival. There is a need to improve on this approach given that only approximately 10% achieve a pathologically complete response. Irinotecan has an established role in the treatment of metastatic rectal cancer. Both in-vitro and in-vivo data have shown promising radiosensitization properties. This study provides an overview of the published clinical trials evaluating the role of irinotecan as a radiosensitizer in the management of locally advanced rectal cancer. Although early-phase clinical trials initially showed promising results, this did not translate into improved outcome in a larger randomized phase II trial. Increased topoisomerase I expression has recently been identified as a possible predictive marker for improved response to irinotecan-based radiosensitization. This finding could help identify a subset of patients more likely to benefit from the addition of irinotecan in future trials. PMID:21160419

  18. Retraction: "Activated K-Ras and INK4a/Arf Deficiency Promote Aggressiveness of Pancreatic Cancer by Induction of EMT Consistent With Cancer Stem Cell Phenotype" by Wang et al.

    PubMed

    2016-10-01

    The above article, published online on November 23, 2012 in Wiley Online Library (wileyonlinelibrary.com), has been retracted by agreement between the journal Editor in Chief, Gary S. Stein, and Wiley Periodicals, Inc. The retraction has been agreed following an investigation from Wayne State University involving the first author and the corresponding author that found Figure 4B and C to be inappropriately manipulated and re-labeled. Literature Cited Wang Z, Ali S, Banerjee S, Bao B, Li Y, Azmi AS, Korc M, Sarkar FH. 2013. Activated K-Ras and INK4a/Arf deficiency promote aggressiveness of pancreatic cancer by induction of EMT consistent with cancer stem cell phenotype. J Cell Physiol 228:556-562; doi: 10.1002/jcp.24162. PMID:27315162

  19. Retraction: "Inactivation of Ink4a/Arf Leads to Deregulated Expression of miRNAs in K-Ras Transgenic Mouse Model of Pancreatic Cancer" by Ali et al.

    PubMed

    2016-10-01

    The above article, published online on June 21, 2012 in Wiley Online Library (wileyonlinelibrary.com), has been retracted by agreement between the journal Editor in Chief, Gary S. Stein, and Wiley Periodicals, Inc. The retraction has been agreed following an investigation from Wayne State University involving the first author and the corresponding author that found Figure 5A to be inappropriately manipulated. Literature Cited Ali S, Banerjee S, Logna F, Bao B, Philip PA, Korc M, Sarkar FH. 2012. Inactivation of Ink4a/Arf leads to deregulated expression of miRNAs in K-Ras transgenic mouse model of pancreatic cancer. J Cell Physiol 227:3373-3380; doi: 10.1002/jcp.24036. PMID:27315161

  20. Effects of low-level chronic irradiation on radiosensitivity of mammals: modeling and experimental studies

    NASA Astrophysics Data System (ADS)

    Smirnova, O. A.; Yonezawa, M.

    Effects of low dose rate chronic irradiation on radiosensitivity of mammals mice are studied by experimental and modeling methods Own and reference experiments show that priming chronic low-level short-term and long-term exposures to radiation induce respectively elevated radiosensitivity and lowered radiosensitivity radioresistance in mice The manifestation of these radiosensitization and radioprotection effects are respectively increased and decreased mortality of preirradiated specimens after challenge acute irradiation in comparison with those for previously unexposed ones Taking into account that the reason of the animal death in the experiments was the hematopoietic syndrome the biophysical models of the critical body system hematopoiesis are used to simulate the dynamics of the major hematopoietic lines in mice exposed to challenge acute irradiation following the chronic one Juxtaposition of the modeling results obtained and the relevant experimental data shows that the radiosensitization effect of chronic low-level short-term less than 1 month preirradiation on mice is due to increased radiosensitivity of lymphopoietic granulocytopoietic and erythropoietic systems accompanied by increased or close to the normal level radiosensitivity of thrombocytopoietic system which are induced by the above-indicated exposure In turn the radioprotection effect of chronic low-level long-term more than 1 month preirradiation on mice is caused by decreased radiosensitivity radioresistance of the granulocytopoietic system which

  1. A comprehensive analysis of radiosensitization targets; functional inhibition of DNA methyltransferase 3B radiosensitizes by disrupting DNA damage regulation

    PubMed Central

    Fujimori, Hiroaki; Sato, Akira; Kikuhara, Sota; Wang, Junhui; Hirai, Takahisa; Sasaki, Yuka; Murakami, Yasufumi; Okayasu, Ryuichi; Masutani, Mitsuko

    2015-01-01

    A comprehensive genome-wide screen of radiosensitization targets in HeLa cells was performed using a shRNA-library/functional cluster analysis and DNMT3B was identified as a candidate target. DNMT3B RNAi increased the sensitivity of HeLa, A549 and HCT116 cells to both γ-irradiation and carbon-ion beam irradiation. DNMT3B RNAi reduced the activation of DNA damage responses induced by γ-irradiation, including HP1β-, γH2AX- and Rad51-foci formation. DNMT3B RNAi impaired damage-dependent H2AX accumulation and showed a reduced level of γH2AX induction after γ-irradiation. DNMT3B interacted with HP1β in non-irradiated conditions, whereas irradiation abrogated the DNMT3B/HP1β complex but induced interaction between DNMT3B and H2AX. Consistent with radiosensitization, TP63, BAX, PUMA and NOXA expression was induced after γ-irradiation in DNMT3B knockdown cells. Together with the observation that H2AX overexpression canceled radiosensitization by DNMT3B RNAi, these results suggest that DNMT3B RNAi induced radiosensitization through impairment of damage-dependent HP1β foci formation and efficient γH2AX-induction mechanisms including H2AX accumulation. Enhanced radiosensitivity by DNMT3B RNAi was also observed in a tumor xenograft model. Taken together, the current study implies that comprehensive screening accompanied by a cluster analysis enabled the identification of radiosensitization targets. Downregulation of DNMT3B, one of the targets identified using this method, radiosensitizes cancer cells by disturbing multiple DNA damage responses. PMID:26667181

  2. A comprehensive analysis of radiosensitization targets; functional inhibition of DNA methyltransferase 3B radiosensitizes by disrupting DNA damage regulation.

    PubMed

    Fujimori, Hiroaki; Sato, Akira; Kikuhara, Sota; Wang, Junhui; Hirai, Takahisa; Sasaki, Yuka; Murakami, Yasufumi; Okayasu, Ryuichi; Masutani, Mitsuko

    2015-01-01

    A comprehensive genome-wide screen of radiosensitization targets in HeLa cells was performed using a shRNA-library/functional cluster analysis and DNMT3B was identified as a candidate target. DNMT3B RNAi increased the sensitivity of HeLa, A549 and HCT116 cells to both γ-irradiation and carbon-ion beam irradiation. DNMT3B RNAi reduced the activation of DNA damage responses induced by γ-irradiation, including HP1β-, γH2AX- and Rad51-foci formation. DNMT3B RNAi impaired damage-dependent H2AX accumulation and showed a reduced level of γH2AX induction after γ-irradiation. DNMT3B interacted with HP1β in non-irradiated conditions, whereas irradiation abrogated the DNMT3B/HP1β complex but induced interaction between DNMT3B and H2AX. Consistent with radiosensitization, TP63, BAX, PUMA and NOXA expression was induced after γ-irradiation in DNMT3B knockdown cells. Together with the observation that H2AX overexpression canceled radiosensitization by DNMT3B RNAi, these results suggest that DNMT3B RNAi induced radiosensitization through impairment of damage-dependent HP1β foci formation and efficient γH2AX-induction mechanisms including H2AX accumulation. Enhanced radiosensitivity by DNMT3B RNAi was also observed in a tumor xenograft model. Taken together, the current study implies that comprehensive screening accompanied by a cluster analysis enabled the identification of radiosensitization targets. Downregulation of DNMT3B, one of the targets identified using this method, radiosensitizes cancer cells by disturbing multiple DNA damage responses. PMID:26667181

  3. Combined inhibition of Wee1 and PARP1/2 for radiosensitization in pancreatic cancer

    PubMed Central

    Karnak, David; Engelke, Carl G.; Parsels, Leslie A.; Kausar, Tasneem; Wei, Dongping; Robertson, Jordan R.; Marsh, Katherine B.; Davis, Mary A.; Zhao, Lili; Maybaum, Jonathan; Lawrence, Theodore S.; Morgan, Meredith A.

    2014-01-01

    Purpose While the addition of radiation to chemotherapy improves survival in patients with locally advanced pancreatic cancer, more effective therapies are urgently needed. Thus, we investigated the radiosensitizing efficacy of the novel drug combination of Wee1 and PARP1/2 [poly (ADP-ribose) polymerase 1/2] inhibitors (AZD1775 and olaparib, respectively) in pancreatic cancer. Experimental Design Radiosensitization of AsPC-1 or MiaPaCa-2 human pancreatic cancer cells was assessed by clonogenic survival and tumor growth assays. Mechanistically, the effects of AZD1775, olaparib, and radiation on cell cycle, DNA damage (γH2AX) and HRR (homologous recombination repair) were determined. Results Treatment of AsPC-1 and MiaPaCa-2 cells with either AZD1775 or olaparib caused modest radiosensitization while treatment with the combination significantly increased radiosensitization. Radiosensitization by the combination of AZD1775 and olaparib was associated with G2 checkpoint abrogation and persistent DNA damage. In addition, AZD1775 inhibited HRR activity and prevented radiation-induced Rad51 focus formation. Finally, in vivo, in MiaPaCa-2-derived xenografts, olaparib did not radiosensitize, while AZD1775 produced moderate, yet significant, radiosensitization (P<0.05). Importantly, the combination of AZD1775 and olaparib produced highly significant radiosensitization (P<0.0001) evidenced by a 13-day delay in tumor volume doubling (vs radiation alone) and complete eradication of 20% of tumors. Conclusions Taken together, these results demonstrate the efficacy of combined inhibition of Wee1 and PARP inhibitors for radiosensitizing pancreatic cancers and support the model that Wee1 inhibition sensitizes cells to PARP inhibitor-mediated radiosensitization through inhibition of HRR and abrogation of the G2 checkpoint, ultimately resulting in unrepaired, lethal DNA damage and radiosensitization. PMID:25117293

  4. Radiosensitizing Properties of Bortezomib Depend on Therapeutic Schedule

    SciTech Connect

    Labussiere, Marianne; Pinel, Sophie; Vandamme, Marc; Plenat, Francois; Chastagner, Pascal

    2011-03-01

    Purpose: To investigate the influence of the bortezomib (BTZ) on malignant glioma radiosensitivity in two xenograft models. Methods and Materials: For TCG3 and U87 models, we evaluated the antitumor activity of BTZ, radiotherapy, and BTZ plus radiothearapy according to two therapeutic schedules: a 'nonfractionated' schedule corresponding to a single dose of treatment per week, and a 'fractionated' schedule corresponding to the same weekly dose divided into 5 fractions. Treatments influence on proliferation and apoptosis indexes, cell cycle distribution, and nuclear factor-{kappa}B pathway were explored. Results: The radiosensitizing properties of BTZ observed with the nonfractionated schedule were lost with the fractionated schedule. Bortezomib-mediated radiosensitization was associated with an increased apoptosis response and major changes in cell proliferation, but the nuclear factor-{kappa}B pathway was not involved. Most of the cellular effects induced by BTZ when tumors received a single irradiation were cancelled out if radiotherapy was fractionated. Conclusion: The influence of BTZ on glioma radiosensitivity seems to depend on the treatment fractionation schedule, emphasizing the need to clarify the mechanisms underlying BTZ's radiosensitizing effects before further clinical trials are initiated.

  5. The Search for New Hypoxic Cell Radiosensitizers

    PubMed Central

    Mansfield, Carl M.; Kimler, Bruce F.; Cheng, C.C.; Abrahams, Iris L.; Podrebarac, Eugene G.; Wittek, Philip J.; Reddy, Eashwer K.

    1980-01-01

    A number of newly synthesized compounds whose chemical structure suggested possible or remotely possible ability to radiosensitize hypoxic mammalian cells were studied in an in-vitro system. Those compounds that were not excluded because of insolubility or extreme cytotoxicity were tested for radiosensitizing ability. The correlation between chemical structure and radiosensitizing ability will be used for the rational design of additional compounds with a high probability of being effective hypoxic cell radiosensitizers. It is hoped that this will contribute to attempts to improve the cure rate of patients with malignant tumors through the use of radiation therapy and hypoxic cell radiosensitizers. PMID:7401185

  6. Synthesis and radiosensitization properties of hydrogen peroxide and sodium hyaluronate complex

    SciTech Connect

    Rosli, Nur Ratasha Alia Md.; Mohamed, Faizal; Heng, Cheong Kai; Rahman, Irman Abdul; Ahmad, Ainee Fatimah; Mohamad, Hur Munawar Kabir

    2014-09-03

    Cancer cells which are large in size are resistant towards radiation therapy due to the presence of large amount of anti-oxidative enzymes and hypoxic cancer cells. Thus radiosensitizer agents have been developed to enhance the therapeutic effect of radiotherapy by increasing the sensitivity of these cancer cells towards radiation. This study is conducted to investigate the radiosensitization properties of radiosensitizer complex containing hydrogen peroxide and sodium hyaluronate. Combination with sodium hyaluronate may decrease reactivity of hydrogen peroxide but maintain the oxygen concentration needed for radiosensitizing effect. HepG2 cancer cells are cultured as the mean of test subject. Cancer cell samples which are targeted and not targeted with these radiosensitizers are irradiated with 2Gy single fractionated dose. Results obtained shows that the cancer cells which are not targeted with radiosensitizers has a cell viability of 98.80±0.37% after a time interval of 48 hours and has even repopulated over 100% after a 72 hour time interval. This shows that the cancer cells are resistant towards radiation. However, when the cancer cells are targeted with radiosensitizers prior to irradiation, there is a reduction of cell viability by 25.50±10.81% and 10.30±5.10% at time intervals of 48 and 72 hours respectively. This indicates that through the use of these radiosensitizers, cancer cells are more sensitive towards radiation.

  7. G9a/RelB regulates self-renewal and function of colon-cancer-initiating cells by silencing Let-7b and activating the K-RAS/β-catenin pathway.

    PubMed

    Cha, Shih-Ting; Tan, Ching-Ting; Chang, Cheng-Chi; Chu, Chia-Yu; Lee, Wei-Jiunn; Lin, Been-Zen; Lin, Ming-Tsan; Kuo, Min-Liang

    2016-09-01

    Epigenetic reprogramming has been associated with the functional plasticity of cancer-initiating cells (CICs); however, the regulatory pathway has yet to be elucidated. A siRNA screen targeting known epigenetic genes revealed that G9a profoundly impairs the chemo-resistance, self-renewal and metastasis of CICs obtained from patients with colorectal cancer (CRC). Patients with elevated G9a were shown to face a high risk of relapse and poor survival rates. From a mechanistic perspective, G9a binds with and stabilizes RelB, thereby recruiting DNA methyltransferase 3 on the Let-7b promoter and repressing its expression. This leads to the activation of the K-RAS/β-catenin pathway and regulates self-renewal and function of CICs. These findings indicate that the G9a/RelB/Let-7b axis acts as a critical regulator in the maintenance of CIC phenotypes and is strongly associated with negative clinical outcomes. Thus, these findings may have diagnostic as well as therapeutic implications for the treatment of chemotherapy-resistant or metastatic CRC. PMID:27525719

  8. Targeted radiosensitization of cells expressing truncated DNA polymerase {beta}.

    PubMed

    Neijenhuis, Sari; Verwijs-Janssen, Manon; van den Broek, Lenie J; Begg, Adrian C; Vens, Conchita

    2010-11-01

    Ionizing radiation (IR) is an effective anticancer treatment, although failures still occur. To improve radiotherapy, tumor-targeted strategies are needed to increase radiosensitivity of tumor cells, without influencing normal tissue radiosensitivity. Base excision repair (BER) and single-strand break repair (SSBR) contribute to the determination of sensitivity to IR. A crucial protein in BER/SSBR is DNA polymerase β (polβ). Aberrant polβ expression is commonly found in human tumors and leads to inhibition of BER. Here, we show that truncated polβ variant (polβ-Δ)-expressing cells depend on homologous recombination (HR) for survival after IR, indicating that a considerable fraction of polβ-Δ-induced lesions are subject to repair by HR. Increased sensitization was found not to result from involvement in DNA-dependent protein kinase-dependent nonhomologous end joining, the other major double-strand break repair pathway. Caffeine and the ATM inhibitor Ku55933 cause polβ-Δ-dependent radiosensitization. Consistent with the observed HR dependence and the known HR-modulating activity of ATM, polβ-Δ-expressing cells showed increased radiosensitization after BRCA2 knockdown that is absent under ATM-inhibited conditions. Our data suggest that treatment with HR modulators is a promising therapeutic strategy for exploiting defects in the BER/SSBR pathway in human tumors. PMID:20978197

  9. Differentiation and radiosensitivity of hemopoietic stem cells of mice during hypokinesia

    NASA Technical Reports Server (NTRS)

    Shvets, V. N.

    1980-01-01

    The potential for differentiation and radiosensitivity of the stem hemopoietic cells (KOE) under conditions of initial and later hypokinesia is examined. It is established that in the initial period of hypokinesia (3 days) when a stress reaction prevails, changes occur in the erythroid differentiation and radiosensitivity of KOE. This effect is associated with redistribution of T-lymphocytes that increase in number in the bone marrow of mice during hypokinesia. At later periods of hypokinesia (30 days) when changes in the organism are related to hypokinesia proper, differentiation and radiosensitivity of KOE were normalized.

  10. Cyclopentenylcytosine does not enhance cisplatin-induced radiosensitization in human lung tumour cells

    PubMed Central

    RODERMOND, HANS M.; CATE, ROSEMARIE TEN; HAVEMAN, JAAP; VAN KUILENBURG, ANDRÉ; MEDEMA, JAN PAUL; VAN BREE, CHRIS; FRANKEN, NICOLAAS A.P.

    2010-01-01

    The search for agents that enhance the effect of ionizing radiation has been an object of study for decades. In this study, the sensitizing properties of cyclopentenylcytosine (CPEC) on radiation and cisplatin-induced radiosensitization in human squamous lung carcinoma cells were investigated. Human lung tumour SW-1573 cells (SWp, parental; SWg, gemcitabine-resistant) were incubated with CPEC and cisplatin and subsequently irradiated with different doses of γ-rays. Clonogenic survival was determined to measure the effectiveness of the treatments. CPEC (1 or 2 μM) treatment for 4 h decreased the plating efficiency to 75 and 50% in SWp and SWg cells, respectively. In the SWg cells, 0.1 and 1 μM CPEC for 4 h enhanced the cell killing effect of cisplatin. However, an increase was not noted in the SWp cells. Due to the moderate toxicity of 1 μM for 4 h, this CPEC dose was used in the radiosensitization experiments. However, CPEC neither radiosensitized the lung tumour cells nor enhanced the radiosensitizing effect of cisplatin. A 2-h incubation with 4 μM cisplatin also decreased the plating efficiency to 75–80% in the two cell lines. Using this cisplatin dose, radiosensitization was obtained in the two cell lines. Although cisplatin treatment clearly radiosensitized the lung tumour cells, CPEC treatment did not. Cisplatin-induced radiosensitization was also not enhanced by CPEC. PMID:22966339

  11. Disturbance of redox status enhances radiosensitivity of hepatocellular carcinoma

    PubMed Central

    Sun, Chao; Wang, Zhen-hua; Liu, Xiong-xiong; Yang, Li-na; Wang, Yali; Liu, Yang; Mao, Ai-hong; Liu, Yuan-yuan; Zhou, Xin; Di, Cui-xia; Gan, Lu; Zhang, Hong

    2015-01-01

    Aims: High constitutive expression of Nrf2 has been found in many types of cancers, and this high level of Nrf2 also favors resistance to drugs and radiation. Here we investigate how isoliquiritigenin (ISL), a natural antioxidant, inhibits the Nrf2-dependent antioxidant pathway and enhances the radiosensitivity of HepG2 cells and HepG2 xenografts. Results: Treatment of HepG2 cells with ISL for 6 h selectively enhanced transcription and expression of Keap1. Keap1 effectively induced ubiquitination and degradation of Nrf2, and inhibited translocation of Nrf2 to the nucleus. Consequently, expression of Nrf2 downstream genes was reduced, and the Nrf2-dependent antioxidant system was suppressed. Endogenous ROS was higher than before ISL treatment, causing redox imbalance and oxidative stress in HepG2 cells. Moreover, pretreatment with ISL for 6 h followed by X-ray irradiation significantly increased γ-H2AX foci and cell apoptosis, and reduced clonogenic potential compared with cells irradiated with X-rays alone. In addition, HepG2 xenografts, ISL, and X-ray co-treatments induced greater apoptosis and tumor growth inhibition, when compared with X-ray treatments alone. Additionally, HepG2 xenografts, in which Nrf2 was expressed at very low levels due to ectopic expression of Keap1, showed that ISL-mediated radiosensitization was Keap1 dependent. Innovation and Conclusions: ISL inhibited the Nrf2-antioxidant pathway by increasing the levels of Keap1 and ultimately inducing oxidative stress via disturbance of the redox status. The antioxidant ISL possessed pro-oxidative properties, and enhanced the radiosensitivity of liver cancer cells, both in vivo and in vitro. Taken together, these results demonstrated the effectiveness of using ISL to decrease radioresistance, suggesting that ISL could be developed as an adjuvant radiosensitization drug. Disturbance of redox status could be a potential target for radiosensitization. PMID:26101703

  12. Heat inactivation of Ku autoantigen: possible role in hyperthermic radiosensitization.

    PubMed

    Burgman, P; Ouyang, H; Peterson, S; Chen, D J; Li, G C

    1997-07-15

    Heat shock prior, during, or immediately after ionizing radiation synergistically increases cell killing, a phenomenon termed hyperthermic radiosensitization. Recently, we have shown a constitutive DNA-binding factor in rodent cells that is inactivated by heat shock to be identical to Ku autoantigen. Ku, consisting of an Mr 70,000 (Ku70) and an Mr 86,000 (Ku80) subunit, is a heterodimeric nuclear protein and is the DNA-binding regulatory component of the mammalian DNA-dependent protein kinase DNA-PK. Recent genetic and biochemical studies indicate the involvement of Ku and DNA-PK in DNA double-strand break repair and V(D)J recombination. On the basis of these findings, we propose that heat-induced loss of the DNA-binding activity of Ku may lead to hyperthermic radiosensitization. To test this hypothesis, we examined and compared the DNA-binding activity of Ku, the DNA-PK kinase activity, and hyperthermic radiosensitization in rodent cells immediately after heat shock and during post-heat shock recovery at 37 degrees C. Our results show that the heat-induced loss of Ku-DNA binding activity correlates well with an increased radiosensitivity of the heat-shocked cells, and furthermore, the loss of synergistic interaction between heat and radiation parallels the recovery of the DNA-binding activity of Ku. On the other hand, the heat-induced decrease of DNA-PK activity did not correlate with hyperthermic radiosensitization. Our data, for the first time, provide evidence for a role of Ku protein in modulating the cellular response to combined treatments of heat shock and ionizing radiation. PMID:9230187

  13. Base excision repair of both uracil and oxidatively damaged bases contribute to thymidine deprivation-induced radiosensitization

    SciTech Connect

    Allen, Bryan G.; Johnson, Monika; Marsh, Anne E.; Dornfeld, Kenneth J. . E-mail: kenneth-dornfeld@uiowa.edu

    2006-08-01

    Purpose: Increased cellular sensitivity to ionizing radiation due to thymidine depletion is the basis of radiosensitization with fluoropyrimidine and methotrexate. The mechanism responsible for cytotoxicity has not been fully elucidated but appears to involve both the introduction of uracil into, and its removal from, DNA. The role of base excision repair of uracil and oxidatively damaged bases in creating the increased radiosensitization during thymidine depletion is examined. Methods and Materials: Isogenic strains of S. cerevisiae differing only at loci involved in DNA repair functions were exposed to aminopterin and sulfanilamide to induce thymidine deprivation. Cultures were irradiated and survival determined by clonogenic survival assay. Results: Strains lacking uracil base excision repair (BER) activities demonstrated less radiosensitization than the parental strain. Mutant strains continued to show partial radiosensitization with aminopterin treatment. Mutants deficient in BER of both uracil and oxidatively damaged bases did not demonstrate radiosensitization. A recombination deficient rad52 mutant strain was markedly sensitive to radiation; addition of aminopterin increased radiosensitivity only slightly. Radiosensitization observed in rad52 mutants was also abolished by deletion of the APN1, NTG1, and NTG2 genes. Conclusion: These data suggest radiosensitization during thymidine depletion is the result of BER activities directed at both uracil and oxidatively damaged bases.

  14. Radiosensitizing Effect of TRPV1 Channel Inhibitors in Cancer Cells.

    PubMed

    Nishino, Keisuke; Tanamachi, Keisuke; Nakanishi, Yuto; Ide, Shunta; Kojima, Shuji; Tanuma, Sei-Ichi; Tsukimoto, Mitsutoshi

    2016-07-01

    Radiosensitizers are used in cancer therapy to increase the γ-irradiation susceptibility of cancer cells, including radioresistant hypoxic cancer cells within solid tumors, so that radiotherapy can be applied at doses sufficiently low to minimize damage to adjacent normal tissues. Radiation-induced DNA damage is repaired by multiple repair systems, and therefore these systems are potential targets for radiosensitizers. We recently reported that the transient receptor potential vanilloid type 1 (TRPV1) channel is involved in early responses to DNA damage after γ-irradiation of human lung adenocarcinoma A549 cells. Therefore, we hypothesized that TRPV1 channel inhibitors would have a radiosensitizing effect by blocking repair of radiation-induced cell damage. Here, we show that pretreatment of A549 cells with the TRPV1 channel inhibitors capsazepine, AMG9810, SB366791 and BCTC suppressed the γ-ray-induced activation of early DNA damage responses, i.e., activation of the protein kinase ataxia-telangiectasia mutated (ATM) and accumulation of p53-binding protein 1 (53BP1). Further, the decrease of survival fraction at one week after γ-irradiation (2.0 Gy) was enhanced by pretreatment of cells with these inhibitors. On the other hand, inhibitor pretreatment did not affect cell viability, the number of apoptotic or necrotic cells, or DNA synthesis at 24 h after irradiation. These results suggest that inhibition of DNA repair by TRPV1 channel inhibitors in irradiated A549 cells caused gradual loss of proliferative ability, rather than acute facilitation of apoptosis or necrosis. TRPV1 channel inhibitors could be novel candidates for radiosensitizers to improve the efficacy of radiation therapy, either alone or in combination with other types of radiosensitizers. PMID:27150432

  15. Andrographolide radiosensitizes human ovarian cancer SKOV3 xenografts due to an enhanced apoptosis and autophagy.

    PubMed

    Zhang, Chao; Qiu, Xingsheng

    2015-11-01

    Andrographolide (AND), a diterpenoid lactone isolated from Andrographis paniculata, has been shown to have radiosensitivity in several types of cancer. Whether AND can radiosensitize ovarian cancer remains unknown. The present study investigated the radiosensitizing effects of AND in human ovarian SKOV3 xenografts and examined the molecular mechanisms of AND-mediated radiosensitization. Nude mice bearing human ovarian SKOV3 were treated with AND to investigate the effects of drug administration on tumor growth, radiosensitivity, apoptosis, and autophagy. Subsequent Western blot analysis and monodansylcadaverine (MDC) staining (autophagy analysis) were used to determine the role of AND. Finally, the pathway of apoptosis was characterized by caspase-3 activity assay as well as TUNEL analysis. AND potently sensitized SKOV3 xenografts to radiation. Moreover, apoptosis and autophagy in radiation combined with drug-treated xenografts increased significantly compared with the simple drug or single radiation treatment. This result was associated with an increase in the Bax/Bcl-2 protein ratio and p-p53 expression after exposure to combination treatment. Meanwhile, the level of Beclin 1 and Atg5 and the conversion from LC3-I to LC3-II, three important proteins involved in autophagy, were increased. AND acts as a strong radiosensitizer in human ovarian SKOV3 xenografts in vivo by increasing the Bax/Bcl-2 protein ratio and promoting the activation of caspase-3, leading to enhanced apoptosis as well as autophagy. PMID:26014516

  16. Suppression of autophagy augments the radiosensitizing effects of STAT3 inhibition on human glioma cells

    SciTech Connect

    Yuan, Xiaopeng; Du, Jie; Hua, Song; Zhang, Haowen; Gu, Cheng; Wang, Jie; Yang, Lei; Huang, Jianfeng; Yu, Jiahua Liu, Fenju

    2015-01-15

    Radiotherapy is an essential component of the standard therapy for newly diagnosed glioblastoma. To increase the radiosensitivity of glioma cells is a feasible solution to improve the therapeutic effects. It has been suggested that inhibition of signal transducer and activator of transcription 3 (STAT3) can radiosensitize glioma cells, probably via the activation of mitochondrial apoptotic pathway. In this study, human malignant glioma cells, U251 and A172, were treated with an STAT3 inhibitor, WP1066, or a short hairpin RNA plasmid targeting STAT3 to suppress the activation of STAT3 signaling. The radiosensitizing effects of STAT3 inhibition were confirmed in glioma cells. Intriguingly, combination of ionizing radiation exposure and STAT3 inhibition triggered a pronounced increase of autophagy flux. To explore the role of autophagy, glioma cells were treated with 3-methyladenine or siRNA for autophagy-related gene 5, and it was demonstrated that inhibition of autophagy further strengthened the radiosensitizing effects of STAT3 inhibition. Accordingly, more apoptotic cells were induced by the dual inhibition of autophagy and STAT3 signaling. In conclusion, our data revealed a protective role of autophagy in the radiosensitizing effects of STAT3 inhibition, and inhibition of both autophagy and STAT3 might be a potential therapeutic strategy to increase the radiosensitivity of glioma cells. - Highlights: • Inactivation of STAT3 signaling radiosensitizes malignant glioma cells. • STAT3 inhibition triggers a significant increase of autophagy flux induced by ionizing radiation in glioma cells. • Suppression of autophagy further strengthens the radiosensitizing effects of STAT3 inhibition in glioma cells. • Dual inhibition of autophagy and STAT3 induce massive apoptotic cells upon exposure to ionizing radiation.

  17. Enhanced radiosensitization by the cationic liposome-encapsulated thymidine analogue BrdU through the increased intracellular BrdU-uptake on human melanoma as compared to anionic or nonionic liposomal or free BrdU.

    PubMed

    Kato, Shinya; Kimura, Masatsugu; Miwa, Nobuhiko

    2014-11-01

    The synthetic thymidine analogue, 5-bromo-2'-deoxy-uridine (BrdU) was encapsulated in cationic liposome composed of dipalmitoylphosphatidylcholine, cholesterol and stearylamine (molar ratio = 1/1/0.2; diameter = 120 nm), and the radiosensitization of cationic liposomal BrdU was assessed on human melanoma cells HMV-II, with comparing to anionic or nonionic liposomal BrdU and free-BrdU. HMV-II cells were pretreated by cationic liposomal BrdU or free-BrdU and then exposed to X-ray, followed by WST-8 assay to examine cell proliferation. The radiation-induced change of nuclei was defined with Hoechst33342 staining. The rates of thymidine replacement by BrdU and DNA double-strand breaks on HMV-II cells were determined with an anti-BrdU antibody and anti-53BP1 antibody, respectively. On 7th day after X-ray irradiation at 3 Gy, cell proliferation was suppressed more markedly in the administration of cationic liposomal BrdU than free-BrdU at equivalent BrdU doses. Giant polykaryocytes were observed in cationic liposomal BrdU-treated HMV-II cells. Radiosensitization was enhanced dose-dependently along with BrdU doses of 0.1-0.8 μM in the order: cationic liposomal BrdU > anionic liposomal BrdU > nonionic liposomal BrdU (see symbol) free-BrdU. Similarly, the cationic liposomal BrdU augmented the rate of thymidine-moiety replacement by BrdU and DNA double-strand breaks more appreciably than free-BrdU. Therefore, the cationic liposome-encapsulation of BrdU would be one of favorable drug deliveries for facilitating the X-ray therapy against cancer. PMID:26000387

  18. Ganetespib radiosensitization for liver cancer therapy

    PubMed Central

    Chettiar, Sivarajan T.; Malek, Reem; Annadanam, Anvesh; Nugent, Katriana M.; Kato, Yoshinori; Wang, Hailun; Cades, Jessica A.; Taparra, Kekoa; Belcaid, Zineb; Ballew, Matthew; Manmiller, Sarah; Proia, David; Lim, Michael; Anders, Robert A.; Herman, Joseph M.; Tran, Phuoc T.

    2016-01-01

    ABSTRACT Therapies for liver cancer particularly those including radiation are still inadequate. Inhibiting the stress response machinery is an appealing anti-cancer and radiosensitizing therapeutic strategy. Heat-shock-protein-90 (HSP90) is a molecular chaperone that is a prominent effector of the stress response machinery and is overexpressed in liver cancer cells. HSP90 client proteins include critical components of pathways implicated in liver cancer cell survival and radioresistance. The effects of a novel non-geldanamycin HSP90 inhibitor, ganetespib, combined with radiation were examined on 3 liver cancer cell lines, Hep3b, HepG2 and HUH7, using in vitro assays for clonogenic survival, apoptosis, cell cycle distribution, γH2AX foci kinetics and client protein expression in pathways important for liver cancer survival and radioresistance. We then evaluated tumor growth delay and effects of the combined ganetespib-radiation treatment on tumor cell proliferation in a HepG2 hind-flank tumor graft model. Nanomolar levels of ganetespib alone exhibited liver cancer cell anti-cancer activity in vitro as shown by decreased clonogenic survival that was associated with increased apoptotic cell death, prominent G2-M arrest and marked changes in PI3K/AKT/mTOR and RAS/MAPK client protein activity. Ganetespib caused a supra-additive radiosensitization in all liver cancer cell lines at low nanomolar doses with enhancement ratios between 1.33–1.78. These results were confirmed in vivo, where the ganetespib-radiation combination therapy produced supra-additive tumor growth delay compared with either therapy by itself in HepG2 tumor grafts. Our data suggest that combined ganetespib-radiation therapy exhibits promising activity against liver cancer cells, which should be investigated in clinical studies. PMID:26980196

  19. [Cisplatin influence on: the radiosensitivity and recovery of yeast cells].

    PubMed

    Evstratova, E S; Petin, V G

    2013-01-01

    The effect of the simultaneous combined action of ionizing radiation and cisplatin on the radiosensitivity and liquid holding recovery (LHR) of diploid yeast cells was studied. It was shown that regardless of the cisplatin concentration (0; 0.002; 0.01; 0.02 g/ml) the radiosensitivity of cells was increased by 1.3 times. The ability of a cell to the LHR was progressively decreased with the increasing cisplatin concentration up to the complete inhibition. It was shown that the LHR of yeast cells after a combined action of ionizing radiation and chemical agents is mainly inhibited due to formation of a greater proportion of irreversible damage. The constant of recovery, characterizing the probability of recovery per a unit of time, was independent on cisplatine concentration. PMID:25486742

  20. [Cisplatin influence on: the radiosensitivity and recovery of yeast cells].

    PubMed

    2013-01-01

    The effect of the simultaneous combined action of ionizing radiation and cisplatin on the radiosensitivity and liquid holding recovery (LHR) of diploid yeast cells was studied. It was shown that regardless of the cisplatin concentration (0; 0.002; 0.01; 0.02 g/ml) the radiosensitivity of cells was increased by 1.3 times. The ability of a cell to the LHR was progressively decreased with the increasing cisplatin concentration up to the complete inhibition. It was shown that the LHR of yeast cells after a combined action of ionizing radiation and chemical agents is mainly inhibited due to formation of a greater proportion of irreversible damage. The con- stant of recovery, characterizing the probability of recovery per a unit of time, was independent on cisplatine concentration. PMID:25508873

  1. Circadian rhythmometry of mammalian radiosensitivity

    NASA Technical Reports Server (NTRS)

    Haus, E.; Halberg, F.; Loken, M. K.; Kim, Y. S.

    1974-01-01

    In the case of human bone marrow, the largest number of mitoses is seen in the evening in diurnally active men, mitotic activity being at a minimum in the morning. The opposite pattern is observed for nocturnal animals such as rats and mice on a regimen of light during the daytime alternating with darkness during the night hours. The entirety of these rhythms plays an important role in the organism's responses to environmental stimuli, including its resistance to potentially harmful agents. Conditions under which circadian rhythms can be observed and validated by inferential statistical means are discussed while emphasizing how artifacts of the laboratory environment can be shown to obscure circadian periodic variations in radiosensitivity.

  2. Radiosensitization: enhancing the radiation inactivation of foodborne bacteria

    NASA Astrophysics Data System (ADS)

    Borsa, J.; Lacroix, M.; Ouattara, B.; Chiasson, F.

    2004-09-01

    Irradiation of meat products to kill pathogens can be limited by radiation-induced detriment of sensory quality. Since such detriment is directly related to dose, one approach to reduce it is by devising means to lower the dose of radiation required for processing. Increasing the radiation sensitivity of the target microorganisms would lower the dose required for a given level of microbial kill. In this work, the radiation sensitivities of inoculated Escherichia coli and Salmonella typhi in ground beef were examined under a variety of conditions. Results showed that specific manipulations of treatment conditions significantly increased the radiation sensitivity of the test organisms, ranging from a few percent to several-fold reduction in D10. In particular, radiation sensitization could be effected by certain additives, including carvacrol, thymol and trans-cinnamaldehyde, and also by certain compositions of modified atmosphere in the package headspace. A combination of additives and modified atmosphere effected a greater radiosensitization effect than could be achieved by either factor applied alone. Radiosensitization could be demonstrated with irradiation of either fresh or frozen ground meat. The radiosensitization phenomenon may be of practical utility in enhancing the technical effectiveness and feasibility of irradiation of a variety of meat and other food products.

  3. DNA-PKcs-Dependent Modulation of Cellular Radiosensitivity by a Selective Cyclooxygenase-2 Inhibitor

    SciTech Connect

    Kodym, Elisabeth; Kodym, Reinhard; Chen, Benjamin P.; Chen, David J.; Morotomi-Yano, Keiko; Choy, Hak; Saha, Debabrata

    2007-09-01

    Purpose: Inhibition of cyclooxygenase-2 has been shown to increase radiosensitivity. Recently, the suppression of radiation-induced DNA-dependant protein kinase (DNA-PK) activity by the selective cyclooxygenase-2 inhibitor celecoxib was reported. Given the importance of DNA-PK for repair of radiation-induced DNA double-strand breaks by nonhomologous end-joining and the clinical use of the substance, we investigated the relevance of the DNA-PK catalytic subunit (DNA-PKcs) for the modulation of cellular radiosensitivity by celecoxib. Methods and Materials: We used a syngeneic model of Chinese hamster ovarian cell lines: AA8, possessing a wild-type DNK-PKcs; V3, lacking a functional DNA-PKcs; and V3/WT11, V3 stably transfected with the DNA-PKcs. The cells were treated with celecoxib (50 {mu}M) for 24 h before irradiation. The modulation of radiosensitivity was determined using the colony formation assay. Results: Treatment with celecoxib increased the cellular radiosensitivity in the DNA-PKcs-deficient cell line V3 with a dose-enhancement ratio of 1.3 for a surviving fraction of 0.5. In contrast, clonogenic survival was increased in DNA-PKcs wild-type-expressing AA8 cells and in V3 cells transfected with DNA-PKcs (V3/WT11). The decrease in radiosensitivity was comparable to the radiosensitization in V3 cells, with a dose-enhancement ratio of 0.76 (AA8) and 0.80 (V3/WT11) for a survival of 0.5. Conclusions: We have demonstrated a DNA-PKcs-dependent differential modulation of cellular radiosensitivity by celecoxib. These effects might be attributed to alterations in signaling cascades downstream of DNA-PK toward cell survival. These findings offer an explanation for the poor outcomes in some recently published clinical trials.

  4. Individual Radiosensitivity Measured With Lymphocytes May Predict the Risk of Acute Reaction After Radiotherapy

    SciTech Connect

    Borgmann, Kerstin; Hoeller, Ulrike; Nowack, Sven; Bernhard, Michael; Roeper, Barbara; Brackrock, Sophie; Petersen, Cordula; Szymczak, Silke; Ziegler, Andreas; Feyer, Petra; Alberti, Winfried; Dikomey, Ekkehard

    2008-05-01

    Purpose: We tested whether the chromosomal radiosensitivity of in vitro irradiated lymphocytes could be used to predict the risk of acute reactions after radiotherapy. Methods and Materials: Two prospective studies were performed: study A with 51 patients included different tumor sites and study B included 87 breast cancer patients. Acute reaction was assessed using the Radiation Therapy Oncology Group score. In both studies, patients were treated with curative radiotherapy, and the mean tumor dose applied was 55 Gy (40-65) {+-} boost with 11 Gy (6-31) in study A and 50.4 Gy {+-} boost with 10 Gy in study B. Individual radiosensitivity was determined with lymphocytes irradiated in vitro with X-ray doses of either 3 or 6 Gy and scoring the number of chromosomal deletions. Results: Acute reactions displayed a typical spectrum with 57% in study A and 53% in study B showing an acute reaction of Grade 2-3. Individual radiosensitivity in both studies was characterized by a substantial variation and the fraction of patients with Grade 2-3 reaction was found to increase with increasing individual radiosensitivity measured at 6 Gy (study A, p = 0.238; study B, p = 0.023). For study B, this fraction increased with breast volume, and the impact of individual radiosensitivity on acute reaction was especially pronounced (p = 0.00025) for lower breast volume. No such clear association with acute reaction was observed when individual radiosensitivity was assessed at 3 Gy. Conclusion: Individual radiosensitivity determined at 6 Gy seems to be a good predictor for risk of acute effects after curative radiotherapy.

  5. Silibinin Preferentially Radiosensitizes Prostate Cancer by Inhibiting DNA Repair Signaling.

    PubMed

    Nambiar, Dhanya K; Rajamani, Paulraj; Deep, Gagan; Jain, Anil K; Agarwal, Rajesh; Singh, Rana P

    2015-12-01

    Radiotherapy, a frequent mode of cancer treatment, is often restricted by dose-related toxicity and development of therapeutic resistance. To develop a novel and selective radiosensitizer, we studied the radiosensitizing effects and associated mechanisms of silibinin in prostate cancer. The radiosensitizing effect of silibinin with ionizing radiation (IR) was assessed on radioresistant prostate cancer cell lines by clonogenic, cell cycle, cell death, and DNA repair assays. Tumor xenograft growth, immunohistochemical (IHC) analysis of tumor tissues, and toxicity-related parameters were measured in vivo. Silibinin (25 μmol/L) enhanced IR (2.5-10 Gy)-caused inhibition (up to 96%, P < 0.001) of colony formation selectively in prostate cancer cells, and prolonged and enhanced IR-caused G2-M arrest, apoptosis, and ROS production. Mechanistically, silibinin inhibited IR-induced DNA repair (ATM and Chk1/2) and EGFR signaling and attenuated the levels of antiapoptotic proteins. Specifically, silibinin suppressed IR-induced nuclear translocation of EGFR and DNA-PK, an important mediator of DSB repair, leading to an increased number of γ-H2AX (ser139) foci suggesting lesser DNA repair. In vivo, silibinin strongly radiosensitized DU145 tumor xenograft inhibition (84%, P < 0.01) with higher apoptotic response (10-fold, P < 0.01) and reduced repair of DNA damage, and rescued the mice from IR-induced toxicity and hematopoietic injury. Overall, silibinin enhanced the radiotherapeutic response via suppressing IR-induced prosurvival signaling and DSB repair by inhibiting nuclear translocation of EGFR and DNA-PK. Because silibinin is already in phase II clinical trial for prostate cancer patients, the present finding has translational relevance for radioresistant prostate cancer. PMID:26516160

  6. Low-Dose Radiation Cataract and Genetic Determinants of Radiosensitivity

    SciTech Connect

    Kleiman, Norman Jay

    2013-11-30

    The lens of the eye is one of the most radiosensitive tissues in the body. Ocular ionizing radiation exposure results in characteristic, dose related, progressive lens changes leading to cataract formation. While initial, early stages of lens opacification may not cause visual disability, the severity of such changes progressively increases with dose until vision is impaired and cataract extraction surgery may be required. Because of the transparency of the eye, radiation induced lens changes can easily be followed non-invasively over time. Thus, the lens provides a unique model system in which to study the effects of low dose ionizing radiation exposure in a complex, highly organized tissue. Despite this observation, considerable uncertainties remain surrounding the relationship between dose and risk of developing radiation cataract. For example, a growing number of human epidemiological findings suggest significant risk among various groups of occupationally and accidentally exposed individuals and confidence intervals that include zero dose. Nevertheless, questions remain concerning the relationship between lens opacities, visual disability, clinical cataract, threshold dose and/or the role of genetics in determining radiosensitivity. Experimentally, the response of the rodent eye to radiation is quite similar to that in humans and thus animal studies are well suited to examine the relationship between radiation exposure, genetic determinants of radiosensitivity and cataractogenesis. The current work has expanded our knowledge of the low-dose effects of X-irradiation or high-LET heavy ion exposure on timing and progression of radiation cataract and has provided new information on the genetic, molecular, biochemical and cell biological features which contribute to this pathology. Furthermore, findings have indicated that single and/or multiple haploinsufficiency for various genes involved in DNA repair and cell cycle checkpoint control, such as Atm, Brca1 or Rad9

  7. Radiosensitization effect of zidovudine on human malignant glioma cells

    SciTech Connect

    Zhou Fuxiang; Liao Zhengkai; Dai Jing; Xiong Jie; Xie CongHua; Luo Zhiguo; Liu Shiquan; Zhou Yunfeng . E-mail: yfzhouwhu@163.com

    2007-03-09

    Telomeres are shortened with each cell division and play an important role in maintaining chromosomal integrity and function. Telomerase, responsible for telomere synthesis, is activated in 90% of human tumor cells but seldom in normal somatic cells. Zidovudine (AZT) is a reverse transcriptase inhibitor. In this study, we have investigated the effects of {gamma}-radiation in combination with AZT on telomerase activity (TA), telomere length, DNA single-strand breaks (SSBs), DNA double-strand breaks (DSBs), and the changes in radiosensitivity of human malignant glioma cell line U251. The results showed that the TA was suppressed by AZT but enhanced by irradiation, resulting in a deceleration of restored rate of shortened telomere, decreased repair rate of DNA strand breaks, and increased radiosensitivity of U251 cells. Our results suggested that telomerase activity and telomere length may serve as markers for estimating the efficacy of cancer radiotherapy and reverse transcriptase inhibitors, such as AZT, may be used clinically as a new radiosensitizer in cancer radiotherapy.

  8. Cellular and Molecular Mechanisms Underlying Oxygen-Dependent Radiosensitivity

    PubMed Central

    Liu, Chao; Lin, Qun; Yun, Zhong

    2015-01-01

    Molecular oxygen has long been recognized as a powerful radiosensitizer that enhances the cell-killing efficiency of ionizing radiation. Radiosensitization by oxygen occurs at very low concentrations with the half-maximum radiosensitization at approximately 3 mmHg. However, robust hypoxia-induced signal transduction can be induced at <15 mmHg and can elicit a wide range of cellular responses that will affect therapy response as well as malignant progression. Great strides have been made, especially since the 1990s, toward identification and characterization of the oxygen-regulated molecular pathways that affect tumor response to ionizing radiation. In this review, we will discuss the current advances in our understanding of oxygen-dependent molecular modification and cellular signal transduction and their impact on tumor response to therapy. We will specifically address mechanistic distinctions between radiobiological hypoxia (0–3 mmHg) and pathological hypoxia (3–15 mmHg). We also propose a paradigm that hypoxia increases radioresistance by maintaining the cancer stem cell phenotype. PMID:25938770

  9. Dependence of Gold Nanoparticle Radiosensitization on Functionalizing Layer Thickness.

    PubMed

    Spaas, Cedric; Dok, Rüveyda; Deschaume, Olivier; De Roo, Bert; Vervaele, Mattias; Seo, Jin Won; Bartic, Carmen; Hoet, Peter; Van den Heuvel, Frank; Nuyts, Sandra; Locquet, Jean-Pierre

    2016-04-01

    Gold nanoparticles functionalized with polyethylene glycol of different chain lengths are used to determine the influence of the capping layer thickness on the radiosensitizing effect of the particles. The size variations in organic coating, built up with polyethylene glycol polymers of molecular weight 1-20 kDa, allow an evaluation of the decrease in dose enhancement percentages caused by the gold nanoparticles at different radial distances from their surface. With localized eradication of malignant cells as a primary focus, radiosensitization is most effective after internalization in the nucleus. For this reason, we performed controlled radiation experiments, with doses up to 20 Gy and particle diameters in a range of 5-30 nm, and studied the relaxation pattern of supercoiled DNA. Subsequent gel electrophoresis of the suspensions was performed to evaluate the molecular damage and consecutively quantify the gold nanoparticle sensitization. In conclusion, on average up to 58.4% of the radiosensitizing efficiency was lost when the radial dimensions of the functionalizing layer were increased from 4.1 to 15.3 nm. These results serve as an experimental supplement for biophysical simulations and demonstrate the influence of an important parameter in the development of nanomaterials for targeted therapies in cancer radiotherapy. PMID:26950059

  10. Clofarabine Acts as Radiosensitizer In Vitro and In Vivo by Interfering With DNA Damage Response

    SciTech Connect

    Cariveau, Mickael J.; Stackhouse, Murray; Cui Xiaoli; Tiwari, Kamal; Waud, William; Secrist, John A.; Xu Bo

    2008-01-01

    Purpose: Combination treatment with radiotherapy and chemotherapy has emerged as the dominant form of cancer adjuvant regimens in recent years. Clofarabine, a newly approved drug for pediatric leukemia, is a second-generation purine nucleoside analogue that can block DNA synthesis and inhibit DNA repair. Therefore, we hypothesized that clofarabine could work synergistically with radiotherapy to increase the tumor cell response. Methods and Materials: The effects of clofarabine on radiosensitivity have been established in several tumor cell lines in vitro and in vivo using colony-forming assays and tumor xenografts. The effect of clofarabine on the DNA damage response was also studied in vitro by measuring {gamma}-H2AX focus formation. Results: Clonogenic survival was significantly reduced in irradiated cells treated with clofarabine, demonstrating the strong radiosensitizing effect of clofarabine. Furthermore, clofarabine displayed a radiosensitizing effect that was greater than gemcitabine or 5-fluorouracil. We also found that low doses of clofarabine can prolong the presence of radiation-induced {gamma}-H2AX nuclear focus formation, and high doses of clofarabine can induce DNA double-strand breaks, suggesting that clofarabine can interfere with DNA damage response pathways. In addition, clofarabine-induced radiosensitization was also established in vivo using a colorectal cancer model, DLD-1, in athymic nude mice. When combined with fractionated radiotherapy, a moderate dose of clofarabine led to a significant increase in tumor growth inhibition. Conclusion: Clofarabine acts as a powerful radiosensitizer both in vitro and in vivo by interfering with the DNA damage response.

  11. Lanthanum fluoride nanoparticles for radiosensitization of tumors

    NASA Astrophysics Data System (ADS)

    Kudinov, Konstantin; Bekah, Devesh; Cooper, Daniel; Shastry, Sathvik; Hill, Colin; Bradforth, Stephen; Nadeau, Jay

    2016-03-01

    Dense inorganic nanoparticles have recently been identified as promising radiosensitizers. In addition to dose enhancement through increased attenuation of ionizing radiation relative to biological tissue, scintillating nanoparticles can transfer energy to coupled photosensitizers to amplify production of reactive oxygen species, as well as provide UVvisible emission for optical imaging. Lanthanum fluoride is a transparent material that is easily prepared as nanocrystals, and which can provide radioluminescence at a number of wavelengths through simple substitution of lanthanum ions with other luminescent lanthanides. We have prepared lanthanum fluoride nanoparticles doped with cerium, terbium, or both, that have good spectral overlap with chlorine6 or Rose Bengal photosensitizer molecules. We have also developed a strategy for stable conjugation of the photosensitizers to the nanoparticle surface, allowing for high energy transfer efficiencies on a per molecule basis. Additionally, we have succeeded in making our conjugates colloidally stable under physiological conditions. Here we present our latest results, using nanoparticles and nanoparticle-photosensitizer conjugates to demonstrate radiation dose enhancement in B16 melanoma cells. The effects of nanoparticle treatment prior to 250 kVp x-ray irradiation were investigated through clonogenic survival assays and cell cycle analysis. Using a custom apparatus, we have also observed scintillation of the nanoparticles and conjugates under the same conditions that the cell samples are irradiated.

  12. Radiosensitization by PARP inhibition to proton beam irradiation in cancer cells.

    PubMed

    Hirai, Takahisa; Saito, Soichiro; Fujimori, Hiroaki; Matsushita, Keiichiro; Nishio, Teiji; Okayasu, Ryuichi; Masutani, Mitsuko

    2016-09-01

    The poly(ADP-ribose) polymerase (PARP)-1 regulates DNA damage responses and promotes base excision repair. PARP inhibitors have been shown to enhance the cytotoxicity of ionizing radiation in various cancer cells and animal models. We have demonstrated that the PARP inhibitor (PARPi) AZD2281 is also an effective radiosensitizer for carbon-ion radiation; thus, we speculated that the PARPi could be applied to a wide therapeutic range of linear energy transfer (LET) radiation as a radiosensitizer. Institutes for biological experiments using proton beam are limited worldwide. This study was performed as a cooperative research at heavy ion medical accelerator in Chiba (HIMAC) in National Institute of Radiological Sciences. HIMAC can generate various ion beams; this enabled us to compare the radiosensitization effect of the PARPi on cells subjected to proton and carbon-ion beams from the same beam line. After physical optimization of proton beam irradiation, the radiosensitization effect of the PARPi was assessed in the human lung cancer cell line, A549, and the pancreatic cancer cell line, MIA PaCa-2. The effect of the PARPi, AZD2281, on radiosensitization to Bragg peak was more significant than that to entrance region. The PARPi increased the number of phosphorylated H2AX (γ-H2AX) foci and enhanced G2/M arrest after proton beam irradiation. This result supports our hypothesis that a PARPi could be applied to a wide therapeutic range of LET radiation by blocking the DNA repair response. PMID:27425251

  13. On the Path to Seeking Novel Radiosensitizers

    SciTech Connect

    Katz, David; Ito, Emma; Liu Feifei

    2009-03-15

    Radiation therapy is a highly effective cancer treatment modality, and extensive investigations have been undertaken over the years to augment its efficacy in the clinic. This review summarizes the current understanding of the biologic bases underpinning many of the clinically used radiosensitizers. In addition, this review illustrates how the advent of innovative, high-throughput technologies with integration of different disciplines could be harnessed for an expeditious discovery process for novel radiosensitizers, providing an exciting future for such pursuits in radiation biology and oncology.

  14. Radiosensitization of DNA in presence of Pt(II)-based compounds

    NASA Astrophysics Data System (ADS)

    Śmiałek, Małgorzata A.; Ptasińska, Sylwia; Gow, Jason; Pieve, Chiara Da; Mason, Nigel J.

    2014-04-01

    X-ray irradiation of plasmid DNA in presence of platinum (II)-based compounds was carried out in order to assess the radiosensitization capabilities of these drugs. In present investigations pBR322 plasmid DNA was used to monitor the effectiveness of chosen compounds in inducing strand breaks. Samples were incubated in the presence of potential radiosensitisers: platinum (II) bromide and cis-diamminedibromoplatinum (II). The results were examined against a common cancer chemotherapy drug cis-diamminedichloroplatinum (II). It was found that platinum (II) bromide can greatly increase the levels of single- and double-strand break formation observed in the irradiated samples with respect to the samples containing platinum as a radiosensitizer only, possessing very little chemotherapeutic activity. The suggested drugs exhibit much higher level of radiosensitivity than widely used cisplatin and thus may be good candidates for cancer treatment.

  15. Effect of anemia on tumor radiosensitivity under normo and hyperbaric conditions

    SciTech Connect

    Rojas, A.; Stewart, F.A.; Smith, K.A.; Soranson, J.A.; Randhawa, V.S.; Stratford, M.R.; Denekamp, J.

    1987-11-01

    The effect of chronic anemia on tumor radiosensitivity in a murine tumor has been investigated. Anemia was induced by bilateral kidney irradiation given several months before tumor implantation. Anemic, anemic transfused, and normal non-anemic age-matched tumor bearing animals were irradiated with X rays (2 F/24 hr) either in air, air plus misonidazole, or under hyperbaric oxygen. The most resistant response was that of tumors grown in normal mice treated in air. Anemia produced an increase in radiosensitivity which was further enhanced by red blood cell replacement. The most sensitive overall response was seen in the anemic-transfused group treated with HBO.

  16. Tumor radiosensitization by monomethyl auristatin E: mechanism of action and targeted delivery

    PubMed Central

    Crisp, Jessica L.; Jones, Karra A.; Hicks, Angel M.; Scanderbeg, Daniel J.; Nguyen, Quyen T.; Sicklick, Jason K.; Lowy, Andrew M.; Tsien, Roger Y.; Advani, Sunil J.

    2015-01-01

    Intrinsic tumor resistance to radiotherapy limits the efficacy of ionizing radiation (IR). Sensitizing cancer cells specifically to IR would improve tumor control and decrease normal tissue toxicity. The development of tumor targeting technologies allows for developing potent radiosensitizing drugs. We hypothesized that the anti-tubulin agent monomethyl auristatin E (MMAE), a component of a clinically approved antibody-directed conjugate, could function as a potent radiosensitizer and be selectively delivered to tumors using an activatable cell penetrating peptide targeting matrix metalloproteinases and RGD binding integrins (ACPP-cRGD-MMAE). We evaluated the ability of MMAE to radiosensitize both established cancer cells and a low passage cultured human pancreatic tumor cell line using clonogenic and DNA damage assays. MMAE sensitized colorectal and pancreatic cancer cells to IR in a schedule and dose dependent manner correlating with mitotic arrest. Radiosensitization was evidenced by decreased clonogenic survival and increased DNA double strand breaks in irradiated cells treated with MMAE. MMAE in combination with IR resulted in increased DNA damage signaling and activation of CHK1. To test a therapeutic strategy of MMAE and IR, PANC-1 or HCT-116 murine tumor xenografts were treated with non-targeted free MMAE or tumor targeted MMAE (ACPP-cRGD-MMAE). While free MMAE in combination with IR resulted in tumor growth delay, tumor targeted ACPP-cRGD-MMAE with IR produced a more robust and significantly prolonged tumor regression in xenograft models. Our studies identify MMAE as a potent radiosensitizer. Importantly, MMAE radiosensitization can be localized to tumors by targeted activatable cell penetrating peptides. PMID:25681274

  17. Radiosensitized treatment of malignant brain tumors

    NASA Astrophysics Data System (ADS)

    Bloznelyte-Plesniene, Laima

    2003-12-01

    Around 12,000 deaths from glioblastoma occurs within the European Community annually. At present, the best available treatment for malignant brain tumors results in a median survival of patients of 15 months despite surgery, radiotherapy, and chemotherapy. The purpose of this paper is to review our results of radiosensitized treatment of malignant brain tumors.

  18. Homozygous mutation of MTPAP causes cellular radiosensitivity and persistent DNA double-strand breaks

    PubMed Central

    Martin, N T; Nakamura, K; Paila, U; Woo, J; Brown, C; Wright, J A; Teraoka, S N; Haghayegh, S; McCurdy, D; Schneider, M; Hu, H; Quinlan, A R; Gatti, R A; Concannon, P

    2014-01-01

    The study of rare human syndromes characterized by radiosensitivity has been instrumental in identifying novel proteins and pathways involved in DNA damage responses to ionizing radiation. In the present study, a mutation in mitochondrial poly-A-polymerase (MTPAP), not previously recognized for its role in the DNA damage response, was identified by exome sequencing and subsequently associated with cellular radiosensitivity. Cell lines derived from two patients with the homozygous MTPAP missense mutation were radiosensitive, and this radiosensitivity could be abrogated by transfection of wild-type mtPAP cDNA into mtPAP-deficient cell lines. Further analysis of the cellular phenotype revealed delayed DNA repair, increased levels of DNA double-strand breaks, increased reactive oxygen species (ROS), and increased cell death after irradiation (IR). Pre-IR treatment of cells with the potent anti-oxidants, α-lipoic acid and n-acetylcysteine, was sufficient to abrogate the DNA repair and clonogenic survival defects. Our results firmly establish that mutation of the MTPAP gene results in a cellular phenotype of increased DNA damage, reduced repair kinetics, increased cell death by apoptosis, and reduced clonogenic survival after exposure to ionizing radiation, suggesting a pathogenesis that involves the disruption of ROS homeostasis. PMID:24651433

  19. Dependence of 5-fluorouracil-mediated radiosensitization on DNA-directed effects

    SciTech Connect

    Lawrence, T.S.; Davis, M.A.; Maybaum, J. )

    1994-06-15

    Although 5-fluorouracil (FUra) has been demonstrated to be a radiation sensitizer both in the laboratory and the clinic, it is not known whether radiosensitization results primary from FUra's DNA or RNA-directed effects. The authors studied the radiosensitizing effects of FUra [+-] thymidine (dThd) on HT29 human colon cancer cells, which are relatively sensitive to the DNA-directed action of FUra, in comparison to SW620 and HuTu80 human colon cancer cells, which are relatively resistant to FUra's DNA-directed effects. They hypothesized that if FUra were acting chiefly through DNA dependent mechanisms, HT29 cells would (a) show greater radiosensitization than SW620 and HuTu80 cells under the same conditions of exposure; and (b) demonstrate selective reversal of radiation sensitivity (compared to cytotoxicity) in the presence of FUra + dThd, compared to FUra alone. They found that the enhancement ratio produced by a 24 h exposure to 10 [mu]M FUra was significantly greater in HT29 cells compared to SW620 and HuTu80 cells (enhancement ratios of 2.1 [+-] 0.1; 1.1 [+-] 0.1, and 1.3 [+-] 0.1, respectively). Furthermore, in HT29 cells, dThd blocked FUra-mediated radiosensitization to a greater extent than FUra-mediated cytotoxicity. Thus, the hypotheses were confirmed. These findings support the concept that the manipulation of FUra's DNA-dependent actions, for example, through modulators of thymidylate synthase (TS) activity, may increase radiosensitization in clinical trials in the treatment of gastrointestinal cancers. However, since resistance to the DNA-directed effects of fluoropyrimidines can result from mechanisms unrelated to TS inhibition, additional strategies will be required to potentiate fluoropyrimidine-mediated radiosensitization. 15 refs., 2 figs., 1 tab.

  20. ZnFe2O4 nanoparticles for potential application in radiosensitization

    NASA Astrophysics Data System (ADS)

    Hidayatullah, M.; Nurhasanah, I.; Budi, W. S.

    2016-03-01

    Radiosensitizer is a material that can increase the effects of radiation in radiotherapy application. Various materials with high effective atomic number have been developed as a radiosensitizer, such as metal, iron oxide and quantum dot. In this study, ZnFe2O4 nanoparticles are included in iron oxide class were synthesized by precipitation method from the solution of zinc nitrate and ferrite nitrate and followed by calcination at 700° C for 3 hours. The XRD pattern shows that most of the observed peaks can be indexed to the cubic phase of ZnFe2O4 with a lattice parameter of 8.424 Å. SEM image reveals that nanoparticles are the sphere-like shape with size in the range 84-107 nm. The ability of ZnFe2O4 nanoparticles as radiosensitizer was examined by loading those nanoparticles into Escherichia coli cell culture which irradiated with photon energy of 6 MV at a dose of 2 Gy. ZnFe2O4 nanoparticles showed ability to increase the absorbed dose by 0.5 to 1.0 cGy/g. In addition, the presence of 1 g/L ZnFe2O4 nanoparticles resulted in an increase radiation effect by 6.3% higher than if exposed to radiation only. These results indicated that ZnFe2O4 nanoparticles can be used as the radiosensitizer for increasing radiation effect in radiotherapy.

  1. The gangliosides as a possible molecular coupling factor between the proportion of radiosensitive cells in vitro and the metastatic potential in vivo within a human melanoma cell line.

    PubMed Central

    Thomas, C. P.; Buronfosse, A.; Portoukalian, J.; Fertil, B.

    1997-01-01

    With an experimental model of spontaneous lung metastases in immunosuppressed newborn rats, seven clones and variants with different metastatic potential and gangliosides expression were derived from a single parental human melanoma cell line M4Be. The cellular radiosensitivity of M4Be and its seven sublines was estimated using an in vitro colony assay. The total amount of gangliosides in M4Be and its seven sublines was determined by cell extraction and thin-layer chromatography, while the expression of GD3 gangliosides was estimated by flow cytometry with a monoclonal antibody. The radiation-cell survival curves of most clones and variants derived from M4Be showed a zero dose extrapolation clearly lower than 100%, suggesting that two populations of cells of very different radiosensitivity coexist within each of these clones and variants. Although the proportion of radiosensitive cells could be estimated from the shape of the survival curve, its radiosensitivity is too high to be properly evaluated by the colony assay. The eight survival curves differ essentially in the proportion of radiosensitive cells--which varied from 0% to 40% among M4Be and its seven sublines--whereas the cellular radiosensitivity of the radioresistant population was similar among them. The metastatic potential in vivo of M4Be and its seven sublines was not significantly related to the cellular radiosensitivity of their corresponding radioresistant population, but significantly increased with the fraction of radiosensitive cells. This relationship is valid only when the highly metastatic cells are cultured for no more than five passages in vitro as the fraction of radiosensitive cells is rapidly lost during subcultures. The relationship remains valid in vivo as metastatic melanoma-bearing newborn rats whole body irradiated with 20 cGy show no lung metastasis compared with controls. The radiosensitive cell fraction is inversely correlated with both the total ganglioside content (r = 0.84, P

  2. In vitro 3-dimensional tumor model for radiosensitivity of HPV positive OSCC cell lines

    PubMed Central

    Zhang, Mei; Rose, Barbara; Lee, C Soon; Hong, Angela M

    2015-01-01

    The incidence of oropharyngeal squamous cell carcinoma (OSCC) is increasing due to the rising prevalence of human papillomavirus (HPV) positive OSCC. HPV positive OSCC is associated with better outcomes than HPV negative OSCC. Our aim was to explore the possibility that this favorable prognosis is due to the enhanced radiosensitivity of HPV positive OSCC. HPV positive OSCC cell lines were generated from the primary OSCCs of 2 patients, and corresponding HPV positive cell lines generated from nodal metastases following xenografting in nude mice. Monolayer and 3 dimensional (3D) culture techniques were used to compare the radiosensitivity of HPV positive lines with that of 2 HPV negative OSCC lines. Clonogenic and protein assays were used to measure survival post radiation. Radiation induced cell cycle changes were studied using flow cytometry. In both monolayer and 3D culture, HPV positive cells exhibited a heterogeneous appearance whereas HPV negative cells tended to be homogeneous. After irradiation, HPV positive cells had a lower survival in clonogenic assays and lower total protein levels in 3D cultures than HPV negative cells. Irradiated HPV positive cells showed a high proportion of cells in G1/S phase, increased apoptosis, an increased proliferation rate, and an inability to form 3D tumor clumps. In conclusion, HPV positive OSCC cells are more radiosensitive than HPV negative OSCC cells in vitro, supporting a more radiosensitive nature of HPV positive OSCC. PMID:26046692

  3. SU11657 Enhances Radiosensitivity of Human Meningioma Cells

    SciTech Connect

    Milker-Zabel, Stefanie Bois, Angelika Zabel-du; Ranai, Gholamreza; Trinh, Thuy; Unterberg, Andreas; Debus, Juergen; Lipson, Kenneth E.; Abdollahi, Amir; Huber, Peter E.

    2008-03-15

    Purpose: To analyze the effect of the multireceptor tyrosine kinase inhibitor SU11657 (primarily vascular endothelial growth factor, platelet-derived growth factor) in combination with irradiation in freshly isolated primary human meningioma cells. Methods and Materials: Tumor specimens were obtained from meningioma patients undergoing surgery at the Department of Neurosurgery, University of Heidelberg, Germany. For the present study only cells up to passage 6 were used. Benign and atypical meningioma cells and human umbilical vein endothelial cells (HUVEC) were treated with SU11657 alone and in combination with 6-MV photons (0-10 Gy). Clonogenic survival and cell proliferation were determined alone and in coculture assays to determine direct and paracrine effects. Results: Radiation and SU11657 alone reduced cell proliferation in atypical and benign meningioma cells as well as in HUVEC in a dose-dependent manner. SU11657 alone also reduced clonogenic survival of benign and atypical meningioma cells. SU11657 increased radiosensitivity of human meningioma cells in clonogenic survival and cell number/proliferation assays. The anticlonogenic and antiproliferative effects alone and the radiosensitization effects of SU11657 were more pronounced in atypical meningioma cells compared with benign meningioma cells. Conclusion: Small-molecule tyrosine kinase inhibitors like SU11657 are capable of amplifying the growth inhibitory effects of irradiation in meningioma cells. These data provide a rationale for further clinical evaluation of this combination concept, especially in atypical and malignant meningioma patients.

  4. Activating PTEN by COX-2 inhibitors antagonizes radiation-induced AKT activation contributing to radiosensitization

    SciTech Connect

    Meng, Zhen; Gan, Ye-Hua

    2015-05-01

    Radiotherapy is still one of the most effective nonsurgical treatments for many tumors. However, radioresistance remains a major impediment to radiotherapy. Although COX-2 inhibitors can induce radiosensitization, the underlying mechanism is not fully understood. In this study, we showed that COX-2 selective inhibitor celecoxib enhanced the radiation-induced inhibition of cell proliferation and apoptosis in HeLa and SACC-83 cells. Treatment with celecoxib alone dephosphorylated phosphatase and tensin homolog deleted on chromosome ten (PTEN), promoted PTEN membrane translocation or activation, and correspondingly dephosphorylated or inactivated protein kinase B (AKT). By contrast, treatment with radiation alone increased PTEN phosphorylation, inhibited PTEN membrane translocation and correspondingly activated AKT in the two cell lines. However, treatment with celecoxib or another COX-2 selective inhibitor (valdecoxib) completely blocked radiation-induced increase of PTEN phosphorylation, rescued radiation-induced decrease in PTEN membrane translocation, and correspondingly inactivated AKT. Moreover, celecoxib could also upregulate PTEN protein expression by downregulating Sp1 expression, thereby leading to the activation of PTEN transcription. Our results suggested that COX-2 inhibitors could enhance radiosensitization at least partially by activating PTEN to antagonize radiation-induced AKT activation. - Highlights: • COX-2 inhibitor, celecoxib, could enhance radiosensitization. • Radiation induced PTEN inactivation (phosphorylation) and AKT activation. • COX-2 inhibitor induced PTEN expression and activation, and inactivated AKT. • COX-2 inhibitor enhanced radiosensitization through activating PTEN.

  5. RRx-001, A novel dinitroazetidine radiosensitizer.

    PubMed

    Oronsky, Bryan; Scicinski, Jan; Ning, Shoucheng; Peehl, Donna; Oronsky, Arnold; Cabrales, Pedro; Bednarski, Mark; Knox, Susan

    2016-06-01

    The 'holy grail' in radiation oncology is to improve the outcome of radiation therapy (RT) with a radiosensitizer-a systemic chemical/biochemical agent that additively or synergistically sensitizes tumor cells to radiation in the absence of significant toxicity. Similar to the oxygen effect, in which DNA bases modified by reactive oxygen species prevent repair of the cellular radiation damage, these compounds in general magnify free radical formation, leading to the permanent "fixation" of the resultant chemical change in the DNA structure. The purpose of this review is to present the origin story of the radiosensitizer, RRx-001, which emerged from the aerospace industry. The activity of RRx-001 as a chemosensitizer in multiple tumor types and disease states including malaria, hemorrhagic shock and sickle cell anemia, are the subject of future reviews. PMID:26841903

  6. Seeking genetic signature of radiosensitivity - a novel method for data analysis in case of small sample sizes

    PubMed Central

    2014-01-01

    Background The identification of polymorphisms and/or genes responsible for an organism's radiosensitivity increases the knowledge about the cell cycle and the mechanism of the phenomena themselves, possibly providing the researchers with a better understanding of the process of carcinogenesis. Aim The aim of the study was to develop a data analysis strategy capable of discovering the genetic background of radiosensitivity in the case of small sample size studies. Results Among many indirect measures of radiosensitivity known, the level of radiation-induced chromosomal aberrations was used in the study. Mathematical modelling allowed the transformation of the yield-time curve of radiation-induced chromosomal aberrations into the exponential curve with limited number of parameters, while Gaussian mixture models applied to the distributions of these parameters provided the criteria for mouse strain classification. A detailed comparative analysis of genotypes between the obtained subpopulations of mice followed by functional validation provided a set of candidate polymorphisms that might be related to radiosensitivity. Among 1857 candidate relevant SNPs, that cluster in 28 genes, eight SNPs were detected nonsynonymous (nsSNP) on protein function. Two of them, rs48840878 (gene Msh3) and rs5144199 (gene Cc2d2a), were predicted as having increased probability of a deleterious effect. Additionally, rs48840878 is capable of disordering phosphorylation with 14 PKs. In silico analysis of candidate relevant SNP similarity score distribution among 60 CGD mouse strains allowed for the identification of SEA/GnJ and ZALENDE/EiJ mouse strains (95.26% and 86.53% genetic consistency respectively) as the most similar to radiosensitive subpopulation Conclusions A complete step-by-step strategy for seeking the genetic signature of radiosensitivity in the case of small sample size studies conducted on mouse models was proposed. It is shown that the strategy, which is a combination of

  7. Short Hairpin RNA Suppression of Thymidylate Synthase Produces DNA Mismatches and Results in Excellent Radiosensitization

    SciTech Connect

    Flanagan, Sheryl A.; Cooper, Kristin S.; Mannava, Sudha; Nikiforov, Mikhail A.; Shewach, Donna S.

    2012-12-01

    Purpose: To determine the effect of short hairpin ribonucleic acid (shRNA)-mediated suppression of thymidylate synthase (TS) on cytotoxicity and radiosensitization and the mechanism by which these events occur. Methods and Materials: shRNA suppression of TS was compared with 5-fluoro-2 Prime -deoxyuridine (FdUrd) inactivation of TS with or without ionizing radiation in HCT116 and HT29 colon cancer cells. Cytotoxicity and radiosensitization were measured by clonogenic assay. Cell cycle effects were measured by flow cytometry. The effects of FdUrd or shRNA suppression of TS on dNTP deoxynucleotide triphosphate imbalances and consequent nucleotide misincorporations into deoxyribonucleic acid (DNA) were analyzed by high-pressure liquid chromatography and as pSP189 plasmid mutations, respectively. Results: TS shRNA produced profound ({>=}90%) and prolonged ({>=}8 days) suppression of TS in HCT116 and HT29 cells, whereas FdUrd increased TS expression. TS shRNA also produced more specific and prolonged effects on dNTPs deoxynucleotide triphosphates compared with FdUrd. TS shRNA suppression allowed accumulation of cells in S-phase, although its effects were not as long-lasting as those of FdUrd. Both treatments resulted in phosphorylation of Chk1. TS shRNA alone was less cytotoxic than FdUrd but was equally effective as FdUrd in eliciting radiosensitization (radiation enhancement ratio: TS shRNA, 1.5-1.7; FdUrd, 1.4-1.6). TS shRNA and FdUrd produced a similar increase in the number and type of pSP189 mutations. Conclusions: TS shRNA produced less cytotoxicity than FdUrd but was equally effective at radiosensitizing tumor cells. Thus, the inhibitory effect of FdUrd on TS alone is sufficient to elicit radiosensitization with FdUrd, but it only partially explains FdUrd-mediated cytotoxicity and cell cycle inhibition. The increase in DNA mismatches after TS shRNA or FdUrd supports a causal and sufficient role for the depletion of dTTP thymidine triphosphate and consequent DNA

  8. Chromosomal radiosensitivity of human immunodeficiency virus positive/negative cervical cancer patients in South Africa

    PubMed Central

    HERD, OLIVIA; FRANCIES, FLAVIA; KOTZEN, JEFFREY; SMITH, TRUDY; NXUMALO, ZWIDE; MULLER, XANTHENE; SLABBERT, JACOBUS; VRAL, ANNE; BAEYENS, ANS

    2016-01-01

    Cervical cancer is the second most common cancer amongst South African women and is the leading cause of cancer-associated mortality in this region. Several international studies on radiation-induced DNA damage in lymphocytes of cervical cancer patients have remained inconclusive. Despite the high incidence of cervical cancer in South Africa, and the extensive use of radiotherapy to treat it, the chromosomal radiosensitivity of South African cervical cancer patients has not been studied to date. Since a high number of these patients are human immunodeficiency virus (HIV)-positive, the effect of HIV infection on chromosomal radiosensitivity was also investigated. Blood samples from 35 cervical cancer patients (20 HIV-negative and 15 HIV-positive) and 20 healthy controls were exposed to X-rays at doses of 6 MV of 2 and 4 Gy in vitro. Chromosomal radiosensitivity was assessed using the micronucleus (MN) assay. MN scores were obtained using the Metafer 4 platform, an automated microscopic system. Three scoring methods of the MNScore module of Metafer were applied and compared. Cervical cancer patients had higher MN values than healthy controls, with HIV-positive patients having the highest MN values. Differences between groups were significant when using a scoring method that corrects for false positive and false negative MN. The present study suggested increased chromosomal radiosensitivity in HIV-positive South African cervical cancer patients. PMID:26549042

  9. MicroRNA-218 Enhances the Radiosensitivity of Human Cervical Cancer via Promoting Radiation Induced Apoptosis

    PubMed Central

    Yuan, Wang; Xiaoyun, Han; Haifeng, Qiu; Jing, Li; Weixu, Hu; Ruofan, Dong; Jinjin, Yu; Zongji, Shen

    2014-01-01

    We previously reported frequent loss of microRNA-218 (miR-218) in cervical cancer, which was associated with tumor progression and poor prognosis. As microRNAs were found invovled in the regulation of radiosensitivity in various human cancers, we therefore aim to investigate the effects of miR-218 on radiosensitivity of cervical cancer in the present study. The clonogenic survival assay demonstrated that loss of miR-218 could predict radioresistance in the primary cervical cancer cells (R2=0.6516, P<0.001). In vitro, abundant miR-218 increased the radiosensitivity in cervical cancer cells (P<0.001 for HeLa, P=0.009 for SiHa, P=0.016 for C33A and P=0.01 for CaSki). Upregulation of miR-218 significantly enhanced the radiation-induced apoptosis, which was further enhanced by the combination of miR-218 overexpression and radiation In xenograft growth assay, combination of miR-218 overexpression and radiation notably induced cellular apoptosis and suppressed tumor growth. In conclusion, we demonstrated that miR-218 resensitized cervical cancer cells to radiation via promoting cellular apoptosis. Moreover, we proved that miR-218 as a potent predictor of radiosensitivity in cervical cancer, especially for those patients with loss of miR-218. PMID:24843318

  10. Differential Radiosensitizing Effect of Valproic Acid in Differentiation Versus Self-Renewal Promoting Culture Conditions

    SciTech Connect

    Debeb, Bisrat G.; Xu Wei; Mok, Henry; Li Li; Robertson, Fredika; Ueno, Naoto T.; Reuben, Jim; Lucci, Anthony; Cristofanilli, Massimo; Woodward, Wendy A.

    2010-03-01

    Purpose: It has been shown that valproic acid (VA) enhances the proliferation and self-renewal of normal hematopoietic stem cells and that breast cancer stem/progenitor cells can be resistant to radiation. From these data, we hypothesized that VA would fail to radiosensitize breast cancer stem/progenitor cells grown to three-dimensional (3D) mammospheres. Methods and Materials: We used the MCF7 breast cancer cell line grown under stem cell-promoting culture conditions (3D mammosphere) and standard nonstem cell monolayer culture conditions (two-dimensional) to examine the effect of pretreatment with VA on radiation sensitivity in clonogenic survival assays and on the expression of embryonic stem cell transcription factors. Results: 3D-cultured MCF-7 cells expressed higher levels of Oct4, Nanog, and Sox2. The 3D passage enriched self-renewal and increased radioresistance in the 3D mammosphere formation assays. VA radiosensitized adherent cells but radioprotected 3D cells in single-fraction clonogenic assays. Moreover, fractionated radiation sensitized VA-treated adherent MCF7 cells but did not have a significant effect on VA-treated single cells grown to mammospheres. Conclusion: We have concluded that VA might preferentially radiosensitize differentiated cells compared with those expressing stem cell surrogates and that stem cell-promoting culture is a useful tool for in vitro evaluation of novel cancer therapeutic agents and radiosensitizers.

  11. Optimal energy for cell radiosensitivity enhancement by gold nanoparticles using synchrotron-based monoenergetic photon beams

    PubMed Central

    Rahman, Wan Nordiana; Corde, Stéphanie; Yagi, Naoto; Abdul Aziz, Siti Aishah; Annabell, Nathan; Geso, Moshi

    2014-01-01

    Gold nanoparticles have been shown to enhance radiation doses delivered to biological targets due to the high absorption coefficient of gold atoms, stemming from their high atomic number (Z) and physical density. These properties significantly increase the likelihood of photoelectric effects and Compton scattering interactions. Gold nanoparticles are a novel radiosensitizing agent that can potentially be used to increase the effectiveness of current radiation therapy techniques and improve the diagnosis and treatment of cancer. However, the optimum radiosensitization effect of gold nanoparticles is strongly dependent on photon energy, which theoretically is predicted to occur in the kilovoltage range of energy. In this research, synchrotron-generated monoenergetic X-rays in the 30–100 keV range were used to investigate the energy dependence of radiosensitization by gold nanoparticles and also to determine the photon energy that produces optimum effects. This investigation was conducted using cells in culture to measure dose enhancement. Bovine aortic endothelial cells with and without gold nanoparticles were irradiated with X-rays at energies of 30, 40, 50, 60, 70, 81, and 100 keV. Trypan blue exclusion assays were performed after irradiation to determine cell viability. Cell radiosensitivity enhancement was indicated by the dose enhancement factor which was found to be maximum at 40 keV with a value of 3.47. The dose enhancement factor obtained at other energy levels followed the same direction as the theoretical calculations based on the ratio of the mass energy absorption coefficients of gold and water. This experimental evidence shows that the radiosensitization effect of gold nanoparticles varies with photon energy as predicted from theoretical calculations. However, prediction based on theoretical assumptions is sometimes difficult due to the complexity of biological systems, so further study at the cellular level is required to fully characterize the

  12. Celecoxib Enhances the Radiosensitizing Effect of 7-Hydroxystaurosporine (UCN-01) in Human Lung Cancer Cell Lines

    SciTech Connect

    Kim, Young-Mee; Jeong, In-Hye; Pyo, Hongryull

    2012-07-01

    Purpose: 7-Hydroxystaurosporine (UCN-01), a Chk1-specific inhibitor, showed promising in vitro and in vivo chemo- or radiosensitizing activity. However, there have been concerns about its limited therapeutic efficacy and risk of side effects. A method of enhancing the treatment efficacy of UCN-01 while not increasing its side effects on normal tissue may therefore be required to apply this drug in clinical settings. Celecoxib is a cyclooxygenase-2 (COX-2)-specific inhibitor that downregulates ataxia telangiectasia and rad3-related (ATR) protein, an upstream kinase of Chk1. In this study, we investigated whether the addition of celecoxib can potentiate the radiosensitizing effect of UCN-01. Methods and Materials: The cooperative radiosensitizing effects and the underlying molecular mechanisms of UCN-01 plus celecoxib were determined by clonogenic assay, tumor growth delay assay, flow cytometry, and Western blotting. Synergism of the three agents combined (UCN-01 plus celecoxib plus radiation) were evaluated using median drug effect analysis and drug-independent action model analysis. Results: The combination of UCN-01 and celecoxib could induce synergistic cytotoxicity and radiosensitizing effects in in vitro and in vivo systems. The combination of both drugs also cooperatively inhibited IR-induced G{sub 2}/M arrest, and increased the G{sub 2} to mitotic transition. Conclusions: Combined treatment with UCN-01 and celecoxib can exert synergistically enhanced radiosensitizing effects via cooperative inhibition of the ionizing radiation-activated G{sub 2} checkpoint. We propose that this combination strategy may be useful in clinical applications of UCN-01 for radiotherapy of cancer patients.

  13. Optimal energy for cell radiosensitivity enhancement by gold nanoparticles using synchrotron-based monoenergetic photon beams.

    PubMed

    Rahman, Wan Nordiana; Corde, Stéphanie; Yagi, Naoto; Abdul Aziz, Siti Aishah; Annabell, Nathan; Geso, Moshi

    2014-01-01

    Gold nanoparticles have been shown to enhance radiation doses delivered to biological targets due to the high absorption coefficient of gold atoms, stemming from their high atomic number (Z) and physical density. These properties significantly increase the likelihood of photoelectric effects and Compton scattering interactions. Gold nanoparticles are a novel radiosensitizing agent that can potentially be used to increase the effectiveness of current radiation therapy techniques and improve the diagnosis and treatment of cancer. However, the optimum radiosensitization effect of gold nanoparticles is strongly dependent on photon energy, which theoretically is predicted to occur in the kilovoltage range of energy. In this research, synchrotron-generated monoenergetic X-rays in the 30-100 keV range were used to investigate the energy dependence of radiosensitization by gold nanoparticles and also to determine the photon energy that produces optimum effects. This investigation was conducted using cells in culture to measure dose enhancement. Bovine aortic endothelial cells with and without gold nanoparticles were irradiated with X-rays at energies of 30, 40, 50, 60, 70, 81, and 100 keV. Trypan blue exclusion assays were performed after irradiation to determine cell viability. Cell radiosensitivity enhancement was indicated by the dose enhancement factor which was found to be maximum at 40 keV with a value of 3.47. The dose enhancement factor obtained at other energy levels followed the same direction as the theoretical calculations based on the ratio of the mass energy absorption coefficients of gold and water. This experimental evidence shows that the radiosensitization effect of gold nanoparticles varies with photon energy as predicted from theoretical calculations. However, prediction based on theoretical assumptions is sometimes difficult due to the complexity of biological systems, so further study at the cellular level is required to fully characterize the effects

  14. Targeting Mcl-1 for Radiosensitization of Pancreatic Cancers12

    PubMed Central

    Wei, Dongping; Zhang, Qiang; Schreiber, Jason S.; Parsels, Leslie A.; Abulwerdi, Fardokht A.; Kausar, Tasneem; Lawrence, Theodore S.; Sun, Yi; Nikolovska-Coleska, Zaneta; Morgan, Meredith A.

    2015-01-01

    In order to identify targets whose inhibition may enhance the efficacy of chemoradiation in pancreatic cancer, we previously conducted an RNAi library screen of 8,800 genes. We identified Mcl-1 (myeloid cell leukemia-1), an anti-apoptotic member of the Bcl-2 family, as a target for sensitizing pancreatic cancer cells to chemoradiation. In the present study we investigated Mcl-1 inhibition by either genetic or pharmacological approaches as a radiosensitizing strategy in pancreatic cancer cells. Mcl-1 depletion by siRNA produced significant radiosensitization in BxPC-3 and Panc-1 cells in association with Caspase-3 activation and PARP cleavage, but only minimal radiosensitization in MiaPaCa-2 cells. We next tested the ability of the recently identified, selective, small molecule inhibitor of Mcl-1, UMI77, to radiosensitize in pancreatic cancer cells. UMI77 caused dissociation of Mcl-1 from the pro-apoptotic protein Bak and produced significant radiosensitization in BxPC-3 and Panc-1 cells, but minimal radiosensitization in MiaPaCa-2 cells. Radiosensitization by UMI77 was associated with Caspase-3 activation and PARP cleavage. Importantly, UMI77 did not radiosensitize normal small intestinal cells. In contrast, ABT-737, an established inhibitor of Bcl-2, Bcl-XL, and Bcl-w, failed to radiosensitize pancreatic cancer cells suggesting the unique importance of Mcl-1 relative to other Bcl-2 family members to radiation survival in pancreatic cancer cells. Taken together, these results validate Mcl-1 as a target for radiosensitization of pancreatic cancer cells and demonstrate the ability of small molecules which bind the canonical BH3 groove of Mcl-1, causing displacement of Mcl-1 from Bak, to selectively radiosensitize pancreatic cancer cells. PMID:25749177

  15. Targeting BRG1 chromatin remodeler via its bromodomain for enhanced tumor cell radiosensitivity in vitro and in vivo.

    PubMed

    Kwon, Su-Jung; Lee, Seul-Ki; Na, Juri; Lee, Shin-Ai; Lee, Han-Sae; Park, Ji-Hye; Chung, June-Key; Youn, Hyewon; Kwon, Jongbum

    2015-02-01

    Radiotherapy treats cancer by inducing DNA double-strand breaks (DSB) in tumor cells using ionizing radiation. However, DNA repair in tumor cells often leads to radioresistance and unsuccessful outcome. Inhibition of DNA repair by targeting repair proteins can increase radiosensitivity of tumor cells. The BRG1 chromatin remodeling enzyme assists DSB repair by stimulating γ-H2AX formation and BRG1 binding to acetylated histones at DSBs via bromodomain (BRD) is critical for this activity. Here, we show that ectopic expression of BRG1-BRD inhibited γ-H2AX and DSB repair after irradiation and increased the radiosensitivity in various human cancer cells, including HT29 colon cancer. Dimerization of BRG1-BRD, increasing its chromatin binding affinity, aggravated the defects in γ-H2AX and DSB repair and further enhanced the radiosensitivity. While little affecting the upstream ATM activation, BRG1-BRD in irradiated HT29 cells inhibited the recruitment of 53BP1 to damaged chromatin, the downstream event of γ-H2AX, and compromised the G2-M checkpoint and increased apoptosis. Importantly, in a xenograft mouse model, BRG1-BRD increased the radiosensitivity of HT29 tumors, which was further enhanced by dimerization. These data suggest that BRG1-BRD radiosensitizes tumor cells by a dominant negative activity against BRG1, which disrupts γ-H2AX and its downstream 53BP1 pathways, leading to inefficient DNA repair, G2-M checkpoint defect, and increased apoptosis. This work therefore identifies BRG1-BRD as a novel tumor radiosensitizer and its action mechanism, providing the first example of chromatin remodeler as a target for improving cancer radiotherapy. PMID:25504753

  16. Prostate-Specific Natural Health Products (Dietary Supplements) Radiosensitize Normal Prostate Cells

    SciTech Connect

    Hasan, Yasmin; Schoenherr, Diane; Martinez, Alvaro A.; Wilson, George D.; Marples, Brian

    2010-03-01

    Purpose: Prostate-specific health products (dietary supplements) are taken by cancer patients to alleviate the symptoms linked with poor prostate health. However, the effect of these agents on evidence-based radiotherapy practice is poorly understood. The present study aimed to determine whether dietary supplements radiosensitized normal prostate or prostate cancer cell lines. Methods and Materials: Three well-known prostate-specific dietary supplements were purchased from commercial sources available to patients (Trinovin, Provelex, and Prostate Rx). The cells used in the study included normal prostate lines (RWPE-1 and PWR-1E), prostate tumor lines (PC3, DU145, and LNCaP), and a normal nonprostate line (HaCaT). Supplement toxicity was assessed using cell proliferation assays [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide] and cellular radiosensitivity using conventional clonogenic assays (0.5-4Gy). Cell cycle kinetics were assessed using the bromodeoxyuridine/propidium iodide pulse-labeling technique, apoptosis by scoring caspase-3 activation, and DNA repair by assessing gammaH2AX. Results: The cell growth and radiosensitivity of the malignant PC3, DU145, and LNcaP cells were not affected by any of the dietary prostate supplements (Provelex [2mug/mL], Trinovin [10mug/mL], and Prostate Rx [50 mug/mL]). However, both Trinovin (10mug/mL) and Prostate Rx (6mug/mL) inhibited the growth rate of the normal prostate cell lines. Prostate Rx increased cellular radiosensitivity of RWPE-1 cells through the inhibition of DNA repair. Conclusion: The use of prostate-specific dietary supplements should be discouraged during radiotherapy owing to the preferential radiosensitization of normal prostate cells.

  17. DNA-Dependent Protein Kinase As Molecular Target for Radiosensitization of Neuroblastoma Cells

    PubMed Central

    Dolman, M. Emmy M.; van der Ploeg, Ida; Koster, Jan; Bate-Eya, Laurel Tabe; Versteeg, Rogier; Caron, Huib N.; Molenaar, Jan J.

    2015-01-01

    Tumor cells might resist therapy with ionizing radiation (IR) by non-homologous end-joining (NHEJ) of IR-induced double-strand breaks. One of the key players in NHEJ is DNA-dependent protein kinase (DNA-PK). The catalytic subunit of DNA-PK, i.e. DNA-PKcs, can be inhibited with the small-molecule inhibitor NU7026. In the current study, the in vitro potential of NU7026 to radiosensitize neuroblastoma cells was investigated. DNA-PKcs is encoded by the PRKDC (protein kinase, DNA-activated, catalytic polypeptide) gene. We showed that PRKDC levels were enhanced in neuroblastoma patients and correlated with a more advanced tumor stage and poor prognosis, making DNA-PKcs an interesting target for radiosensitization of neuroblastoma tumors. Optimal dose finding for combination treatment with NU7026 and IR was performed using NGP cells. One hour pre-treatment with 10 μM NU7026 synergistically sensitized NGP cells to 0.63 Gy IR. Radiosensitizing effects of NU7026 increased in time, with maximum effects observed from 96 h after IR-exposure on. Combined treatment of NGP cells with 10 μM NU7026 and 0.63 Gy IR resulted in apoptosis, while no apoptotic response was observed for either of the therapies alone. Inhibition of IR-induced DNA-PK activation by NU7026 confirmed the capability of NGP cells to, at least partially, resist IR by NHEJ. NU7026 also synergistically radiosensitized other neuroblastoma cell lines, while no synergistic effect was observed for low DNA-PKcs-expressing non-cancerous fibroblasts. Results obtained for NU7026 were confirmed by PRKDC knockdown in NGP cells. Taken together, the current study shows that DNA-PKcs is a promising target for neuroblastoma radiosensitization. PMID:26716839

  18. DNMT (DNA methyltransferase) inhibitors radiosensitize human cancer cells by suppressing DNA repair activity

    PubMed Central

    2012-01-01

    Background Histone modifications and DNA methylation are two major factors in epigenetic phenomenon. Unlike the histone deacetylase inhibitors, which are known to exert radiosensitizing effects, there have only been a few studies thus far concerning the role of DNA methyltransferase (DNMT) inhibitors as radiosensitizers. The principal objective of this study was to evaluate the effects of DNMT inhibitors on the radiosensitivity of human cancer cell lines, and to elucidate the mechanisms relevant to that process. Methods A549 (lung cancer) and U373MG (glioblastoma) cells were exposed to radiation with or without six DNMT inhibitors (5-azacytidine, 5-aza-2'-deoxycytidine, zebularine, hydralazine, epigallocatechin gallate, and psammaplin A) for 18 hours prior to radiation, after which cell survival was evaluated via clonogenic assays. Cell cycle and apoptosis were analyzed via flow cytometry. Expressions of DNMT1, 3A/3B, and cleaved caspase-3 were detected via Western blotting. Expression of γH2AX, a marker of radiation-induced DNA double-strand break, was examined by immunocytochemistry. Results Pretreatment with psammaplin A, 5-aza-2'-deoxycytidine, and zebularine radiosensitized both A549 and U373MG cells. Pretreatment with psammaplin A increased the sub-G1 fraction of A549 cells, as compared to cells exposed to radiation alone. Prolongation of γH2AX expression was observed in the cells treated with DNMT inhibitors prior to radiation as compared with those treated by radiation alone. Conclusions Psammaplin A, 5-aza-2'-deoxycytidine, and zebularine induce radiosensitivity in both A549 and U373MG cell lines, and suggest that this effect might be associated with the inhibition of DNA repair. PMID:22429326

  19. Taxonomic and developmental aspects of radiosensitivity

    SciTech Connect

    Harrison, F.L.; Anderson, S.L.

    1996-11-01

    Considerable information is available on the effects of radioactivity on adult and early life stages of organisms. The preponderance of data is on mortality after a single irradiation with relatively high doses. Unfortunately, because experiments were carried out under different conditions and for different time periods, the validity of comparing the results from different laxonomic groups is questionable. In general, the conclusions are that there is a relationship (1) between radioresistance to high doses of acute radiation and taxonomy of the organism, primitive forms being more radioresistant than complex vertebrates and (2) between radiosensitivity and developmental stage, early life stages being more sensitive than later stages. The first conclusion may be related to the capability of the organism to repopulate cells and to differentiate and redifferentiate them; the second to the rate of cellular division and to the degree of differentiation. In question, however, is the relevance of the responses from high levels of acute radiation to that of the responses to long-term exposure to low levels of radiation, which are ecologically of more interest. Data from studies of the effects of acute and chronic exposure on development of gametes and zygotes indicate that, for some fishes and invertebrates, responses at the cellular and molecular levels show effect levels comparable to those observed in some mammals. Acute doses between 0,05 and 0.5Cy and dose rates between 0.02 to 0.2mCy/h appear to define critical ranges in which detrimental effects on fertility are first observed in a variety of radiosensitive organisms. To better understand inherent radiosensitivity, we need more information on the ability of cells to repopulate and differentiate and to prevent or repair damage to biological critical molecules, such as DNA, because these factors may alter significantly organisms` responses to radiation.

  20. On the mechanism of salivary gland radiosensitivity

    SciTech Connect

    Konings, Antonius W.T. . E-mail: a.w.t.konings@med.rug.nl; Coppes, Rob P.; Vissink, Arjan

    2005-07-15

    Purpose: To contribute to the understanding of the enigmatic radiosensitivity of the salivary glands by analysis of appropriate literature, especially with respect to mechanisms of action of early radiation damage, and to supply information on the possibilities of amelioration of radiation damage to the salivary glands after radiotherapy of head-and-neck cancer. Methods and Materials: Selected published data on the mechanism of salivary gland radiosensitivity and radioprotection were studied and analyzed. Results: From a classical point of view, the salivary glands should not respond as rapidly to radiation as they appear to do. Next to the suggestion of massive apoptosis, the leakage of granules and subsequent lysis of acinar cells was suggested to be responsible for the acute radiation-induced function loss of the salivary glands. The main problem with these hypotheses is that recently performed assays show no cell loss during the first days after irradiation, while saliva flow is dramatically diminished. The water secretion is selectively hampered during the first days after single-dose irradiation. Literature is discussed that shows that the compromised cells suffer selective radiation damage to the plasma membrane, disturbing signal transduction primarily affecting watery secretion. Although the cellular composition of the submandibular gland and the parotid gland are different, the damage response is very alike. The acute radiation-induced function loss in both salivary glands can be ameliorated by prophylactic treatment with specific receptor agonists. Conclusions: The most probable mechanism of action, explaining the enigmatic high radiosensitivity for early effects, is selective radiation damage to the plasma membrane of the secretory cells, disturbing muscarinic receptor stimulated watery secretion. Later damage is mainly due to classical mitotic cell death of progenitor cells, leading to a hampered replacement capacity of the gland for secretory cells

  1. Inhibition of PARP1-dependent end-joining contributes to Olaparib-mediated radiosensitization in tumor cells.

    PubMed

    Kötter, Annika; Cornils, Kerstin; Borgmann, Kerstin; Dahm-Daphi, Jochen; Petersen, Cordula; Dikomey, Ekkehard; Mansour, Wael Y

    2014-12-01

    Poly-ADP-ribose-polymerase inhibitors (PARPi) are considered to be optimal tools for specifically enhancing radiosensitivity. This effect has been shown to be replication-dependent and more profound in HR-deficient tumors. Here, we present a new mode of PARPi-mediated radiosensitization which was observed in four out of six HR-proficient tumor cell lines (responders) investigated, but not in normal cells. This effect is replication-independent, as the radiosensitization remained unaffected following the inhibition of replication using aphidicolin. We showed that responders are radiosensitized by Olaparib because their DSB-repair is switched to PARP1-dependent end-joining (PARP1-EJ), as evident by (i) the significant increase in the number of residual γH2AX foci following irradiation with 3Gy and treatment with Olaparib, (ii) the enhanced enrichment of PARP1 at the chromatin after 3Gy and (iii) the inhibition of end-joining activity measured by a specific reporter substrate upon Olaparib treatment. This is the first study which directly demonstrates the switch to PARP1-EJ in tumor cells and its contribution to the response to Olaparib as a radiosensitizer, findings which could widen the scope of application of PARPi in tumor therapy. PMID:25028150

  2. Relationship between genetic polymorphisms of DNA ligase 1 and non-small cell lung cancer susceptibility and radiosensitivity.

    PubMed

    Tian, H; He, X; Yin, L; Guo, W J; Xia, Y Y; Jiang, Z X

    2015-01-01

    The aim of this study was to examine the relationship between genetic polymorphisms in DNA ligase 1 (LIG1) and non-small cell lung cancer (NSCLC) susceptibility and radiosensitivity in a Chinese population. This was a case-control study that included 352 NSCLC patients and 448 healthy controls. Polymerase chain reaction-restriction fragment length polymorphism analysis was conducted to detect HaeIII polymorphisms in exon 6 of the LIG1 gene in this popula-tion. This information was used to observe the effects of radiation in pa-tients with different genotypes in order to determine the genotypes as-sociated with radiosensitivity. The CC genotype and C allele frequency were significantly higher in the NSCLC group than in the control group (P = 0.012 and P = 0.023, respectively). The relative risk of experienc-ing NSCLC was 2.55 [95% confidence interval (CI), 1.12-3.98] for CC homozygous patients and 0.87 (95%CI, 0.46-1.88) for AA homozygous patients. Analysis of LIG1 genetic polymorphisms and radiosensitiv-ity of NSCLC patients showed that AA homozygous patients were sig-nificantly more radiosensitive than the control group (AA vs AC, P = 0.014; AA vs CC, P < 0.001; AC vs CC, P = 0.023). Therefore, the LIG1 CC genotype was associated with susceptibility to NSCLC, and the AA genotype demonstrated increased radiosensitivity compared to the AC and CC genotypes. PMID:26125914

  3. Radiosensitization by SAHA in Experimental Colorectal Carcinoma Models-In Vivo Effects and Relevance of Histone Acetylation Status

    SciTech Connect

    Folkvord, Sigurd; Ree, Anne Hansen; Furre, Torbjorn; Halvorsen, Thomas; Flatmark, Kjersti

    2009-06-01

    Purpose: Histone deacetylase inhibitors are being evaluated as antitumor agents in ongoing clinical trials, and promising preclinical results, combined with favorable toxicity profiles, have rendered the drugs as interesting candidates for combination with other treatment modalities, such as radiotherapy. The aim of the present study was to evaluate the radiosensitizing properties of suberoylanilide hydroxamic acid (SAHA) and the possible requirement of histone hyperacetylation at radiation exposure. Methods and materials: Radiosensitization by SAHA was assessed in a colorectal carcinoma cell line and in two colorectal xenograft models by analysis of clonogenic survival and tumor growth delay, respectively. Histone acetylation status at radiation exposure was evaluated by Western blot. Results: In vitro, radiosensitization was demonstrated when cells were preincubated with SAHA, and, in the xenografts, tumor growth was delayed when the mice were treated with fractionated radiation combined with daily SAHA injections compared with radiation alone. Surprisingly, the SAHA-dependent growth delay was still present when radiation was delivered at restored baseline acetylation levels compared with maximal histone hyperacetylation. Conclusion: SAHA was an effective radiosensitizer in experimental colorectal carcinoma models, suggesting that histone deacetylase inhibition might constitute a valuable supplement to current multimodal treatment strategies in rectal cancer. The presence of histone hyperacetylation at radiation was not required to obtain an increased radiation response, questioning the validity of using histone hyperacetylation as a molecular marker for radiosensitivity.

  4. Replication-Dependent Radiosensitization of Human Glioma Cells by Inhibition of Poly(ADP-Ribose) Polymerase: Mechanisms and Therapeutic Potential

    SciTech Connect

    Dungey, Fiona A.; Loeser, Dana A.; Chalmers, Anthony J.

    2008-11-15

    Purpose: Current treatments for glioblastoma multiforme are inadequate and limited by the radiation sensitivity of normal brain. Because glioblastoma multiforme are rapidly proliferating tumors within nondividing normal tissue, the therapeutic ratio might be enhanced by combining radiotherapy with a replication-specific radiosensitizer. KU-0059436 (AZD2281) is a potent and nontoxic inhibitor of poly(ADP-ribose) polymerase-1 (PARP-1) undergoing a Phase II clinical trial as a single agent. Methods and Materials: Based on previous observations that the radiosensitizing effects of PARP inhibition are more pronounced in dividing cells, we investigated the mechanisms underlying radiosensitization of human glioma cells by KU-0059436, evaluating the replication dependence of this effect and its therapeutic potential. Results: KU-0059436 increased the radiosensitivity of four human glioma cell lines (T98G, U373-MG, UVW, and U87-MG). Radiosensitization was enhanced in populations synchronized in S phase and abrogated by concomitant exposure to aphidicolin. Sensitization was further enhanced when the inhibitor was combined with a fractionated radiation schedule. KU-0059436 delayed repair of radiation-induced DNA breaks and was associated with a replication-dependent increase in {gamma}H2AX and Rad51 foci. Conclusion: The results of our study have shown that KU-0059436 increases radiosensitivity in a replication-dependent manner that is enhanced by fractionation. A mechanism is proposed whereby PARP inhibition increases the incidence of collapsed replication forks after ionizing radiation, generating persistent DNA double-strand breaks. These observations indicate that KU-0059436 is likely to enhance the therapeutic ratio achieved by radiotherapy in the treatment of glioblastoma multiforme. A Phase I clinical trial is in development.

  5. Radiosensitivity of chromosomes in two successive mitotic cycles of human lymphocytes

    SciTech Connect

    Luchnik, N.V.; Poryadkova, N.A.

    1988-11-01

    A culture of human lymphocytes was irradiated with /gamma/-quanta in a dose of 0.5 Gy with different ratios of cells in first (M1) and second (M2) mitotic cycle and the frequency of aberrations induced at stage G2 was analyzed. With increase in interval of time between the start of culturing and irradiation, total yield of aberrations increased in a regular way. However, if the M1:M2 ratio is considered, then it turns out that in M2 chromosomes are /approximately/1.5 times more sensitive than in M1: within the limits of each cycle, radiosensitivity is constant and does not depend on its duration. It was established in accordance with data of other authors that 5-bromodeoxyuridine (5-BdU) increases radiosensitivity materially.

  6. Radiosensitization of TPGS-emulsified docetaxel-loaded poly(lactic-co-glycolic acid) nanoparticles in CNE-1 and A549 cells.

    PubMed

    Shi, Wei; Yuan, Yin; Chu, Min; Zhao, Shuang; Song, Qingle; Mu, Xiaoqian; Xu, Shuangbing; Zhang, Zhiping; Yang, Kunyu

    2016-03-01

    Docetaxel is among the most effective radiosensitizers. It is widely used as radiosensitizer in many tumors, including head and neck carcinoma. Nevertheless, poor solubility and severe hypersensitivity limit its clinical use and its therapeutic effect remains to be improved. In this study, docetaxel-loaded polymeric nanoparticles were prepared by nanoprecipitation method to be new radiosensitizer with lower side effects and higher efficacy. The physiochemical characteristics of the nanoparticles were studied. Two human tumor cell lines which are resistant to radiotherapy were used in this research. We have compared the radioenhancement efficacy of docetaxel-loaded nanoparticles with docetaxel in A549 and CNE-1 cells. Compared with docetaxel, radiosensitization of docetaxel-loaded nanoparticles was improved significantly (sensitization enhancement ratio in A549 increased 1.24-fold to 1.68-fold when the radiation was applied 2 h after the drug, p < 0.01, sensitization enhancement ratio in CNE-1 increased 1.32-fold to 1.61-fold, p < 0.05). We explored the mechanisms for the radiosensitization efficiency and the difference between docetaxel and docetaxel-loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles. The improved radiosensitization efficacy was associated with enhanced G2/M arrest, promoted apoptosis and the role of D-alpha-tocopheryl polyethylene glycol 1000 succinate which will enhance the cell uptake and inhibit the multiple drug resistance. Moreover, the radiosensitization efficacy of docetaxel-loaded nanoparticles was more prominent than docetaxel. In conclusion, tocopheryl polyethylene glycol 1000 succinate-emulsified docetaxel-loaded PLGA nanoparticles were more efficacious and fewer adverse effects were observed than with the commercial docetaxel formulation. Thus, PLGA nanoparticles hold promise as a radiosensitizing agent. PMID:26608458

  7. Radiosensitization by Inhibiting STAT1 in Renal Cell Carcinoma

    SciTech Connect

    Hui Zhouguang; Tretiakova, Maria; Zhang Zhongfa; Li Yan; Wang Xiaozhen; Zhu, Julie Xiaohong; Gao Yuanhong; Mai Weiyuan; Furge, Kyle; Qian Chaonan; Amato, Robert; Butler, E. Brian

    2009-01-01

    Purpose: Renal cell carcinoma (RCC) has been historically regarded as a radioresistant malignancy, but the molecular mechanism underlying its radioresistance is not understood. This study investigated the role of signal transducer and activator of transcription 1 (STAT1), a transcription factor downstream of the interferon-signaling pathway, in radioresistant RCC. Methods and Materials: The expressions of STAT1 and STAT3 in 164 human clear cell RCC samples, 47 papillary RCC samples, and 15 normal kidney tissue samples were examined by microarray expression profiling and immunohistochemistry. Western blotting was performed to evaluate the total and phosphorylated STAT1 expression in CRL-1932 (786-O) (human clear cell RCC), SKRC-39 (human papillary RCC), CCL-116 (human fibroblast), and CRL-1441 (G-401) (human Wilms tumor). STAT1 was reduced or inhibited by fludarabine and siRNA, respectively, and the effects on radiation-induced cell death were investigated using clonogenic assays. Results: STAT1 expression, but not STAT3 expression, was significantly greater in human RCC samples (p = 1.5 x 10{sup -8} for clear cell; and p = 3.6 x 10{sup -4} for papillary). Similarly, the expression of STAT1 was relatively greater in the two RCC cell lines. STAT1 expression was reduced by both fludarabine and siRNA, significantly increasing the radiosensitivity in both RCC cell lines. Conclusion: This is the first study reporting the overexpression of STAT1 in human clear cell and papillary RCC tissues. Radiosensitization in RCC cell lines was observed by a reduction or inhibition of STAT1 signaling, using fludarabine or siRNA. Our data suggest that STAT1 may play a key role in RCC radioresistance and manipulation of this pathway may enhance the efficacy of radiotherapy.

  8. Andrographolide radiosensitizes human esophageal cancer cell line ECA109 to radiation in vitro.

    PubMed

    Wang, Z-M; Kang, Y-H; Yang, X; Wang, J-F; Zhang, Q; Yang, B-X; Zhao, K-L; Xu, L-P; Yang, L-P; Ma, J-X; Huang, G-H; Cai, J; Sun, X-C

    2016-01-01

    To explore the radiosensitivity of andrographolide on esophageal cancer cell line ECA109. The inhibition effects of andrographolide were measured using 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium (MTT) assay. Clonogenic survival assay was used to evaluate the effects of andrographolide on the radiosensitivity of esophageal cancer cells. Immunofluorescence was employed to examine Bax expression. The changes in cell cycle distribution and apoptosis were assayed using flow cytometry. The expression of NF-κb/Cleaved-Caspase3/Bax/Bcl-2 was measured using Western blot analysis. DNA damage was detected via γ-H2AX foci counting. With a clear dose and time effects, andrographolide was found to inhibit the proliferation of esophageal cell line ECA109. The results of the clonogenic survival assay show that andrographolide could markedly enhance radiosensitivity (P < 0.05) with a sensitizing enhancement ratio of 1.28. Andrographolide caused a dose-dependent increase in Cleaved-Caspase3/Bax protein expression and a decrease in Bcl-2/NF-κb expression. Apoptosis in andrographolide-treated ECA-109 increased significantly compared with the apoptosis in the simple drug and radiation combined with drug groups (P < 0.001; P < 0.05). Moreover, compared with the independent radiation group, the andrographolide combined with radiation group increased the number of DNA double chain breaks. Andrographolide can increase the radiosensitivity of esophageal cell line ECA109. This result may be associated with the decrease in the NF-κb level and the induced apoptosis of esophageal cancer cells. PMID:25059546

  9. HAP1 gene expression is associated with radiosensitivity in breast cancer cells

    SciTech Connect

    Wu, Jing; Zhang, Jun-ying; Yin, Li; Wu, Jian-zhong; Guo, Wen-jie; Wu, Jian-feng; Chen, Meng; Xia, You-you; Tang, Jin-hai; Ma, Yong-chao; He, Xia

    2015-01-02

    Highlights: • Overexpression of HAP1 gene promotes apoptosis in MCF-7 cells after irradiation. • HAP1 reduces tumor volume in nude mice xenograft models after irradiation. • HAP1 increases radiosensitivity of breast cancer cells in vitro and vivo. - Abstract: Objectives: The purpose of this study was to investigate the relationship between huntingtin-associated protein1 (HAP1) gene and radiation therapy of breast cancer cells. Methods: HAP1 gene was transfected into breast cancer MCF-7 cells, which was confirmed by quantitative reverse transcription-polymerase chain reaction analysis (qRT-PCR) and Western blot in vitro. The changes of cell radiosensitivity were assessed by colony formation assay. Apoptosis were examined by flow cytometry. The expressions of two radiation-induced genes were evaluated by Western blot. Tumor growth was investigated in nude mice xenograft models in vivo. Results: Our data showed that HAP1 gene expression was significantly increased in HAP1-transfected MCF-7 cells in comparison with the parental cells or negative control cells. The survival rate in MCF-7/HAP1 cells was significantly decreased after irradiation (0, 2, 4, 6, 8 Gy), compared to cells in MCF-7 and MCF-7/Pb groups in vitro. HAP1 gene increased apoptosis in MCF-7 cells after irradiation. Additionally, the tumor volume and weight in MCF-7/HAP1 + RT group were observably lower than in MCF-7/HAP1 group and MCF-7/Pb + RT group. Conclusion: The present study indicated that HAP1 gene expression was related to the radiosensitivity of breast cancer cells and may play an important role in the regulation of cellular radiosensitivity.

  10. The High Radiosensitizing Efficiency of a Trace of Gadolinium-Based Nanoparticles in Tumors

    NASA Astrophysics Data System (ADS)

    Dufort, Sandrine; Le Duc, Géraldine; Salomé, Murielle; Bentivegna, Valerie; Sancey, Lucie; Bräuer-Krisch, Elke; Requardt, Herwig; Lux, François; Coll, Jean-Luc; Perriat, Pascal; Roux, Stéphane; Tillement, Olivier

    2016-07-01

    We recently developed the synthesis of ultrasmall gadolinium-based nanoparticles (GBN), (hydrodynamic diameter <5 nm) characterized by a safe behavior after intravenous injection (renal clearance, preferential accumulation in tumors). Owing to the presence of gadolinium ions, GBN can be used as contrast agents for magnetic resonance imaging (MRI) and as radiosensitizers. The attempt to determine the most opportune delay between the intravenous injection of GBN and the irradiation showed that a very low content of radiosensitizing nanoparticles in the tumor area is sufficient (0.1 μg/g of particles, i.e. 15 ppb of gadolinium) for an important increase of the therapeutic effect of irradiation. Such a promising and unexpected result is assigned to a suited distribution of GBN within the tumor, as revealed by the X-ray fluorescence (XRF) maps.

  11. The High Radiosensitizing Efficiency of a Trace of Gadolinium-Based Nanoparticles in Tumors

    PubMed Central

    Dufort, Sandrine; Le Duc, Géraldine; Salomé, Murielle; Bentivegna, Valerie; Sancey, Lucie; Bräuer-Krisch, Elke; Requardt, Herwig; Lux, François; Coll, Jean-Luc; Perriat, Pascal; Roux, Stéphane; Tillement, Olivier

    2016-01-01

    We recently developed the synthesis of ultrasmall gadolinium-based nanoparticles (GBN), (hydrodynamic diameter <5 nm) characterized by a safe behavior after intravenous injection (renal clearance, preferential accumulation in tumors). Owing to the presence of gadolinium ions, GBN can be used as contrast agents for magnetic resonance imaging (MRI) and as radiosensitizers. The attempt to determine the most opportune delay between the intravenous injection of GBN and the irradiation showed that a very low content of radiosensitizing nanoparticles in the tumor area is sufficient (0.1 μg/g of particles, i.e. 15 ppb of gadolinium) for an important increase of the therapeutic effect of irradiation. Such a promising and unexpected result is assigned to a suited distribution of GBN within the tumor, as revealed by the X-ray fluorescence (XRF) maps. PMID:27411781

  12. The High Radiosensitizing Efficiency of a Trace of Gadolinium-Based Nanoparticles in Tumors.

    PubMed

    Dufort, Sandrine; Le Duc, Géraldine; Salomé, Murielle; Bentivegna, Valerie; Sancey, Lucie; Bräuer-Krisch, Elke; Requardt, Herwig; Lux, François; Coll, Jean-Luc; Perriat, Pascal; Roux, Stéphane; Tillement, Olivier

    2016-01-01

    We recently developed the synthesis of ultrasmall gadolinium-based nanoparticles (GBN), (hydrodynamic diameter <5 nm) characterized by a safe behavior after intravenous injection (renal clearance, preferential accumulation in tumors). Owing to the presence of gadolinium ions, GBN can be used as contrast agents for magnetic resonance imaging (MRI) and as radiosensitizers. The attempt to determine the most opportune delay between the intravenous injection of GBN and the irradiation showed that a very low content of radiosensitizing nanoparticles in the tumor area is sufficient (0.1 μg/g of particles, i.e. 15 ppb of gadolinium) for an important increase of the therapeutic effect of irradiation. Such a promising and unexpected result is assigned to a suited distribution of GBN within the tumor, as revealed by the X-ray fluorescence (XRF) maps. PMID:27411781

  13. Rational design of cancer-targeted BSA protein nanoparticles as radiosensitizer to overcome cancer radioresistance.

    PubMed

    Huang, Yanyu; Luo, Yi; Zheng, Wenjie; Chen, Tianfeng

    2014-01-01

    Radiotherapy displays curative potential for cervical cancer management, but radioresistance occurs during long-term therapy. To overcome this limitation, tumor-targeted nanotechnology has been proposed to enhance the radiosensitivity of solid tumors. Herein, we used biocompatible bovine serum albumin nanoparticles (BSANPs) as carriers of organic selenocompound (PSeD) with folate (FA) as the targeting ligand to fabricate a cancer-targeted nanosystem. The combination of PSeD and BSANPs endowed the nanosystem with higher light absorption and reactive oxygen species (ROS) generation owing to their properties of surface plasmon resonance (SPR) effect, heavy metal effect, high refractive index and nanoparticulate interfacial effect. The combined treatment drastically increased the ROS overproduction, VEGF/VEGFR2 inactivation and inhibition of XRCC-1-mediated repair of DNA damage, thus triggering G2/M phase arrest and apoptosis. Taken together, our findings demonstrate the utility of FA-BSANPs as a promising radiosensitizer to improve cancer radiotherapy. PMID:25314331

  14. Cellular Pathways in Response to Ionizing Radiation and Their Targetability for Tumor Radiosensitization.

    PubMed

    Maier, Patrick; Hartmann, Linda; Wenz, Frederik; Herskind, Carsten

    2016-01-01

    During the last few decades, improvements in the planning and application of radiotherapy in combination with surgery and chemotherapy resulted in increased survival rates of tumor patients. However, the success of radiotherapy is impaired by two reasons: firstly, the radioresistance of tumor cells and, secondly, the radiation-induced damage of normal tissue cells located in the field of ionizing radiation. These limitations demand the development of drugs for either radiosensitization of tumor cells or radioprotection of normal tissue cells. In order to identify potential targets, a detailed understanding of the cellular pathways involved in radiation response is an absolute requirement. This review describes the most important pathways of radioresponse and several key target proteins for radiosensitization. PMID:26784176

  15. Cellular Pathways in Response to Ionizing Radiation and Their Targetability for Tumor Radiosensitization

    PubMed Central

    Maier, Patrick; Hartmann, Linda; Wenz, Frederik; Herskind, Carsten

    2016-01-01

    During the last few decades, improvements in the planning and application of radiotherapy in combination with surgery and chemotherapy resulted in increased survival rates of tumor patients. However, the success of radiotherapy is impaired by two reasons: firstly, the radioresistance of tumor cells and, secondly, the radiation-induced damage of normal tissue cells located in the field of ionizing radiation. These limitations demand the development of drugs for either radiosensitization of tumor cells or radioprotection of normal tissue cells. In order to identify potential targets, a detailed understanding of the cellular pathways involved in radiation response is an absolute requirement. This review describes the most important pathways of radioresponse and several key target proteins for radiosensitization. PMID:26784176

  16. Molecularly targeted radiosensitization chances towards gene aberration-due organ confined/regionally advanced prostate cancer radioresistance

    PubMed Central

    ALBERTI, C.

    2015-01-01

    Considering that the prostate cancer radioresistance occurs in a significant percentage – as 20–40% of prostate cancer (PCa) patients undergone external beam radiation therapy developing, within ten years, recurrent and more aggressive tumor – the resort to customized radiosensitizer measures, focusly targeting PCa radioresistance-linked individual molecular aberrations, can increase the successful outcomes of PCa radiotherapy. PMID:26188759

  17. Radiosensitivity of cultured insect cells: II. Diptera

    SciTech Connect

    Koval, T.M.

    1983-10-01

    The radiosensitivity of five dipteran cell lines representing three mosquito genera and one fruit fly genus were examined. These lines are: (1) ATC-10, Aedes aegypti; (2) RU-TAE-14, Toxorhynchites amboinensis; (3) RU-ASE-2A, Anopheles stephensi; (4) WR69-DM-1, Drosophila melanogaster; and (5) WR69-DM-2, Drosophila melanogaster. Population doubling times for these lines range from approximately 16 to 48 hr. Diploid chromosome numbers are six for the mosquito cells and eight for the fruit fly cells D/sub 0/ values are 5.1 and 6.5 Gy for the Drosophila cell lines and 3.6, 6.2, and 10.2 Gy for the mosquito cell lines. The results of this study demonstrate that dipteran insect cells are a few times more resistant to radiation than mammalian cells, but not nearly as radioresistant as lepidopteran cells.

  18. Metabolic potentiation of the radiosensitization of hypoxic bacterial cells afforded by nitroaromatic compounds.

    PubMed

    Anderson, R F; Patel, K B

    1983-03-01

    Prolonged preirradiation incubation of nitroaromatic radiosensitizers with Escherichia coli cells has been found to increase the degree of radiosensitization of the cells in anoxia. Studies with E. coli strains which differ in their nitroreductase activity indicate that the increase in sensitization arises from the action of metabolites produced by the nitroreductase system of the cell. The metabolites alone appear to decrease the extrapolation number of irradiated hypoxic cells and when combined with the parent compound give a biphasic survival curve. The combination of misonidazole (1 mmole dm-3) and its metabolites (1 mmole dm-3) gave initial and final enhancement ratios of 2.4 and 1.4, respectively. The final enhancement ratio is that expected for 1 mmole dm-3 misonidazole alone, whereas the initial enhancement ratio indicates that the metabolites potentiate the action of misonidazole. The preirradiation incubation effect is removed by dithiothreitol at concentrations which do not affect the radiosensitization level of the nitroaromatic sensitizer. This result indicates that the active metabolite probably depletes a certain amount of the free-thiol compounds inside the cell which assist in the repair of radiation-induced damage. PMID:6344127

  19. Cell-Specific Radiosensitization by Gold Nanoparticles at Megavoltage Radiation Energies

    SciTech Connect

    Jain, Suneil; Coulter, Jonathan A.; Hounsell, Alan R.; Butterworth, Karl T.; McMahon, Stephen J.; Hyland, Wendy B.; Muir, Mark F.; Dickson, Glenn R.; Prise, Kevin M.; Currell, Fred J.; O'Sullivan, Joe M.; Hirst, David G.

    2011-02-01

    Purpose: Gold nanoparticles (GNPs) have been shown to cause sensitization with kilovoltage (kV) radiation. Differences in the absorption coefficient between gold and soft tissue, as a function of photon energy, predict that maximum enhancement should occur in the kilovoltage (kV) range, with almost no enhancement at megavoltage (MV) energies. Recent studies have shown that GNPs are not biologically inert, causing oxidative stress and even cell death, suggesting a possible biological mechanism for sensitization. The purpose of this study was to assess GNP radiosensitization at clinically relevant MV X-ray energies. Methods and Materials: Cellular uptake, intracellular localization, and cytotoxicity of GNPs were assessed in normal L132, prostate cancer DU145, and breast cancer MDA-MB-231 cells. Radiosensitization was measured by clonogenic survival at kV and MV photon energies and MV electron energies. Intracellular DNA double-strand break (DSB) induction and DNA repair were determined and GNP chemosensitization was assessed using the radiomimetic agent bleomycin. Results: GNP uptake occurred in all cell lines and was greatest in MDA-MB-231 cells with nanoparticles accumulating in cytoplasmic lysosomes. In MDA-MB-231 cells, radiation sensitizer enhancement ratios (SERs) of 1.41, 1.29, and 1.16 were achieved using 160 kVp, 6 MV, and 15 MV X-ray energies, respectively. No significant effect was observed in L132 or DU145 cells at kV or MV energies (SER 0.97-1.08). GNP exposure did not increase radiation-induced DSB formation or inhibit DNA repair; however, GNP chemosensitization was observed in MDA-MB-231 cells treated with bleomycin (SER 1.38). Conclusions: We have demonstrated radiosensitization in MDA-MB-231 cells at MV X-ray energies. The sensitization was cell-specific with comparable effects at kV and MV energies, no increase in DSB formation, and GNP chemopotentiation with bleomycin, suggesting a possible biological mechanism of radiosensitization.

  20. The toxic effects, GSH depletion and radiosensitivity by BSO on retinoblastoma

    SciTech Connect

    Xianjin Yi; Li Ding; Yizun Jin; Chuo Ni; Wenji Wang )

    1994-05-15

    Retinoblastoma is the most common intraocular malignant tumor in children. Previous investigations have reported that buthionine sulfoximine (BSO) can deplete intracellular glutathione (GSH) by specific inhibition and increase cellular radiosensitivity. The toxic effects, GSH depletion and radiosensitivity effects of BSO on retinoblastoma cells are reported in this paper. GSH content of retinoblastoma cell lines Y-79, So-Rb50 and retinoblastoma xenograft is 2.7 [+-] 1.3 X 1.0[sup [minus]12] mmol/cell, 1.4 [+-] 0.2 X 1.0[sup [minus]12] mmol/cell, and 2.8 [+-] 1.2 [mu]mol/g, respectively. The ID[sub 50] of BSO on Y-79 and So-Rb50 in air for 3 h exposure is 2.5 mM and 0.2 mM, respectively. GSH depletion by 0.1 mM BSO for 24 h on Y-79 cells and 0.01 mM BSO for 24 h on So-Rb50 cells is 16.35%, and 4.7% of control. GSH depletion in tumor and other organ tissues in retinoblastoma-bearing nude mice after BSO administration is differential. GSH depletion after BSO exposure in Y-79 cells in vitro decreases the Do value of retinoblastoma cells. The SER of 0.01 mM and 0.05 mM BSO for 24 h under hypoxic conditions is 1.21 and 1.36, respectively. Based on these observations, the authors conclude that BSO toxicity on retinoblastoma cells depends on the characteristics of the cell line and that BSO can increase hypoxic retinoblastoma cells' radiosensitivity in vitro. Further study of BSO radiosensitization on retinoblastoma in vivo using nude mouse xenografts is needed. 25 refs., 3 figs., 3 tabs.

  1. Cellular and molecular mechanisms affecting tumour radiosensitivity : An in vitro study

    NASA Astrophysics Data System (ADS)

    Power, Olive Mary

    less in the radiosensitive cell lines at this dose and was directly related to the increased level of apoptosis observed in these cell lines. It is speculated that the induction of apoptosis occurs after cells have attempted to repair damage before the onset of mitosis, eliminating those cells with irreparable damage. Apoptosis at low doses were not significantly different to constitutive levels, suggesting a limited role of apoptosis in the low dose hypersensitivity response previously observed in some of the cell lines in this study. Radiosensitive cell lines also demonstrated reduced initial DNA damage, measured by CHEF, (1.3-1.7 versus 1.8-2.2 excluding mutant radiosensitive phenotypes) and DSB break repair (20-30% versus 15-20%). While the responses to radiation were expectedly varied it is speculated that radioresistance is associated with increased repair while radiosensitivity is associated with increased apoptosis.

  2. Physical basis and biological mechanisms of gold nanoparticle radiosensitization.

    PubMed

    Butterworth, Karl T; McMahon, Stephen J; Currell, Fred J; Prise, Kevin M

    2012-08-21

    The unique properties of nanomaterials, in particular gold nanoparticles (GNPs) have applications for a wide range of biomedical applications. GNPs have been proposed as novel radiosensitizing agents due to their strong photoelectric absorption coefficient. Experimental evidence supporting the application of GNPs as radiosensitizing agents has been provided from extensive in vitro investigation and a relatively limited number of in vivo studies. Whilst these studies provide experimental evidence for the use of GNPs in combination with ionising radiation, there is an apparent disparity between the observed experimental findings and the level of radiosensitization predicted by mass energy absorption and GNP concentration. This review summarises experimental findings and attempts to highlight potential underlying biological mechanisms of response in GNP radiosensitization. PMID:22767423

  3. Metalloporphyrins and their uses as radiosensitizers for radiation therapy

    DOEpatents

    Miura, Michiko; Slatkin, Daniel N.

    2004-07-06

    The present invention covers radiosensitizers containing as an active ingredient halogenated derivatives of boronated porphyrins containing multiple carborane cages having the structure ##STR1## which selectively accumulate in neoplastic tissue within the irradiation volume and thus can be used in cancer therapies including, but not limited to, boron neutron--capture therapy and photodynamic therapy. The present invention also covers methods for using these radiosensitizers in tumor imaging and cancer treatment.

  4. Fulvestrant radiosensitizes human estrogen receptor-positive breast cancer cells

    SciTech Connect

    Wang, Jing; Yang, Qifeng; Haffty, Bruce G.; Li, Xiaoyan; Moran, Meena S.

    2013-02-08

    Highlights: ► Fulvestrant radiosensitizes MCF-7 cells. ► Fulvestrant increases G1 arrest and decreases S phase in MCF-7 cells. ► Fulvestrant down-regulates DNA-PKcs and RAD51 in MCF-7 cells. -- Abstract: The optimal sequencing for hormonal therapy and radiation are yet to be determined. We utilized fulvestrant, which is showing promise as an alternative to other agents in the clinical setting of hormonal therapy, to assess the cellular effects of concomitant anti-estrogen therapy (fulvestrant) with radiation (F + RT). This study was conducted to assess the effects of fulvestrant alone vs. F + RT on hormone-receptor positive breast cancer to determine if any positive or negative combined effects exist. The effects of F + RT on human breast cancer cells were assessed using MCF-7 clonogenic and tetrazolium salt colorimetric (MTT) assays. The assays were irradiated with a dose of 0, 2, 4, 6 Gy ± fulvestrant. The effects of F + RT vs. single adjuvant treatment alone on cell-cycle distribution were assessed using flow cytometry; relative expression of repair proteins (Ku70, Ku80, DNA-PKcs, Rad51) was assessed using Western Blot analysis. Cell growth for radiation alone vs. F + RT was 0.885 ± 0.013 vs. 0.622 ± 0.029 @2 Gy, 0.599 ± 0.045 vs. 0.475 ± 0.054 @4 Gy, and 0.472 ± 0.021 vs. 0.380 ± 0.018 @6 Gy RT (p = 0.003). While irradiation alone induced G2/M cell cycle arrest, the combination of F + RT induced cell redistribution in the G1 phase and produced a significant decrease in the proportion of cells in G2 phase arrest and in the S phase in breast cancer cells (p < 0.01). Furthermore, levels of repair proteins DNA-PKcs and Rad51 were significantly decreased in the cells treated with F + RT compared with irradiation alone. F + RT leads to a decrease in the surviving fraction, increased cell cycle arrest, down regulating of nonhomologous repair protein DNA-PKcs and homologous recombination repair protein RAD51. Thus, our findings suggest that F + RT

  5. [Radioresistance parameters in head and neck cancers and methods to radiosensitize].

    PubMed

    Biau, J; Chautard, E; Miroir, J; Lapeyre, M

    2015-08-01

    Head and neck cancers have been widely studied concerning their sensitivity to radiation therapy. Several parameters affect tumour response to radiation therapy. Some parameters are linked to the tumour. Large or invasive tumours, localization, such as oral cavity or adenopathy, are factors of radioresistance. Others parameters are linked to the patients themselves. Tobacco intoxication during radiotherapy and a low hemoglobin level contribute to radioresistance. More recently, a positive human papilloma virus (HPV) status has been reported to positively affect radiosensitivity. Finally, other parameters are related to tumour biology. Hypoxia, intrinsic radiosensitivity of tumour cells, tumour differentiation and repopulation (provided by Ki-67 index or EGFR level) are components of radiosensitivity. Currently, concurrent chemoradiotherapy is one of the gold standard treatments to overcome clinical outcome of locally advanced head and neck cancer. This combination increases locoregional control and survival. Taxane-based induction chemotherapy can also be an alternative. Another validated approach is the association of radiotherapy with cetuximab (EGFR targeting) but only one randomized study has been published. Fractionation modifications, especially hyperfractionation, have given positive results on both tumour control and survival. Strategies targeting hypoxia improve locoregional control but have less clinical impact. PMID:26119219

  6. Radiosensitizing effect of zinc oxide and silica nanocomposites on cancer cells.

    PubMed

    Generalov, Roman; Kuan, Woo Boon; Chen, Wei; Kristensen, Solveig; Juzenas, Petras

    2015-05-01

    Nanoparticulates responsive to X-rays offer increased efficacy of radiation therapy. However, successful demonstrations of such nanoparticle use are limited so far due to lack of significant radiosensitizing effects or poor nanoparticle stability in a biological system. Zinc oxide (ZnO) is the most promising biocompatible material for medicinal applications. In this paper, we report preparation and characterization of scintillating ZnO/SiO2 core-shell nanoparticles. The ZnO/SiO2 nanoparticles absorb ultraviolet (UV) radiation (below 360nm) and emit green fluorescence (400-750nm, maximum 550nm). Under X-ray irradiation (200kVp), the nanoparticles scintillate emitting luminescence in the region 350-700nm (maximum 420nm). The synthesized ZnO/SiO2 nanoparticles are stable in a biologically relevant environment (water and cell growth medium). The potential of the ZnO/SiO2 nanoparticles for radiosensitization is demonstrated in human prostate adenocarcinoma cell lines (LNCaP and Du145). The nanoparticles enhance radiation-induced reduction in cell survival about 2-fold for LNCaP and 1.5-fold for Du145 cells. Radiosensitizing effect can be attributed to X-ray-induced radiocatalysis by the nanoparticles. PMID:25829130

  7. Radiosensitizing effect of medroxyprogesterone acetate on endometrial cancer cells in vitro

    SciTech Connect

    Huber, H.; Husslein, P.; Michalica, W.; Wagenbichler, P.

    1984-09-15

    From clinical experience it is known that medroxyprogesterone acetate (MPA) can increase the radiosensitivity of adenocarcinomas of the corpus uteri. This study investigates this phenomenon in vitro. Primary explants of highly differentiated adenocarcinomas were irradiated with or without pretreatment with MPA and compared with an untreated control group and to a group treated with MPA only. Cell culture itself was performed on an agarose medium in order to prevent overgrowth by fibroblasts. Untreated samples formed 43 +/- 5 clones, explants treated with MPA only produced 39 +/- 5 clones, a difference which was not statistically different; samples irradiated without pretreatment produced 16 +/- 8 and samples after combined treatment 9 +/- 3 clones (all values means +/- SD). This numeric reduction of cell growth through preirradiation treatment with MPA was statistically significant. The effect of MPA as a radiosensitizer may be due to its potential to prolong the radiosensitive G2 phase of the cell cycle. This effect of MPA may be useful also in other hormone-dependent tumors.

  8. Dimethoxycurcumin, a metabolically stable analogue of curcumin enhances the radiosensitivity of cancer cells: Possible involvement of ROS and thioredoxin reductase.

    PubMed

    Jayakumar, Sundarraj; Patwardhan, R S; Pal, Debojyoti; Sharma, Deepak; Sandur, Santosh K

    2016-09-01

    Dimethoxycurcumin (DIMC), a structural analogue of curcumin, has been shown to have more stability, bioavailability, and effectiveness than its parent molecule curcumin. In this paper the radiosensitizing effect of DIMC has been investigated in A549 lung cancer cells. As compared to its parent molecule curcumin, DIMC showed a very potent radiosensitizing effect as seen by clonogenic survival assay. DIMC in combination with radiation significantly increased the apoptosis and mitotic death in A549 cells. This combinatorial treatment also lead to effective elimination of cancer stem cells. Further, there was a significant increase in cellular ROS, decrease in GSH to GSSG ratio and also significant slowdown in DNA repair when DIMC was combined with radiation. In silico docking studies and in vitro studies showed inhibition of thioredoxin reductase enzyme by DIMC. Overexpression of thioredoxin lead to the abrogation of radiosensitizing effect of DIMC underscoring the role of thioredoxin reductase in radiosensitization. Our results clearly demonstrate that DIMC can synergistically enhance the cancer cell killing when combined with radiation by targeting thioredoxin system. PMID:27381867

  9. Comment on 'Implications on clinical scenario of gold nanoparticle radiosensitization in regards to photon energy, nanoparticle size, concentration and location'

    NASA Astrophysics Data System (ADS)

    McMahon, Stephen J.; Prise, Kevin M.; Currell, Fred J.

    2012-01-01

    A recent paper by Lechtman et al (2011 Phys. Med. Biol. 56 4631-47) presented Monte Carlo modelling of gold nanoparticle dose modification. In it, they predict that the introduction of gold nanoparticles has the strongest effect with x-rays at kilovoltage energies, and that negligible increases in dose are expected at megavoltage energies. While these results are in agreement with others in the literature (including those produced by our group), the conclusion that '(gold nanoparticle) radiosensitization using a 6 MV photon source is not clinically feasible' appears to conflict with recently published experimental studies which have shown radiosensitization using 6 MV x-ray sources with relatively low gold concentrations. The increasing disparity between theoretical predictions of dose enhancement and experimental results in the field of gold nanoparticle radiosensitization suggests that, while the ability of gold nanoparticles to modify dose within a tumour volume is well understood, the resulting radiosensitization is not simply correlated with this measure. This highlights the need to validate theoretical predictions of this kind against experimental measurements, to ensure that the scenarios and values being modelled are meaningful within a therapeutic context.

  10. Comment on 'implications on clinical scenario of gold nanoparticle radiosensitization in regard to photon energy, nanoparticle size, concentration and location'.

    PubMed

    McMahon, Stephen J; Prise, Kevin M; Currell, Fred J

    2012-01-01

    A recent paper by Lechtman et al (2011 Phys. Med. Biol. 56 4631-47) presented Monte Carlo modelling of gold nanoparticle dose modification. In it, they predict that the introduction of gold nanoparticles has the strongest effect with x-rays at kilovoltage energies, and that negligible increases in dose are expected at megavoltage energies. While these results are in agreement with others in the literature (including those produced by our group), the conclusion that ‘(gold nanoparticle) radiosensitization using a 6 MV photon source is not clinically feasible’ appears to conflict with recently published experimental studies which have shown radiosensitization using 6 MV x-ray sources with relatively low gold concentrations. The increasing disparity between theoretical predictions of dose enhancement and experimental results in the field of gold nanoparticle radiosensitization suggests that, while the ability of gold nanoparticles to modify dose within a tumour volume is well understood, the resulting radiosensitization is not simply correlated with this measure. This highlights the need to validate theoretical predictions of this kind against experimental measurements, to ensure that the scenarios and values being modelled are meaningful within a therapeutic context. PMID:22156112

  11. Dibutyryl cyclic AMP reduces the radiosensitivity of cultured endothelial cells

    SciTech Connect

    Ward, W.; Molteni, A.; Ts'ao, C.; Hinz, J. )

    1991-03-11

    The purpose of this study was to determine whether dibutyryl cyclic AMP modifies the radiosensitivity of confluent monolayers of bovine aortic endothelial cells (BAEC). Three indices of BAEC function were monitored from 4-24 hrs after exposure to 1-10 Gy of {sup 60}Co gamma rays: the release of {sup 51}Cr from prelabeled cells, and release of lactate dehydrogenase (LDH) and plasminogen activator (PLA) into the culture medium. There was a time- and radiation dose-dependent increase in {sup 51}Cr, LDH and PLA release from the BAEC, detectable within 12 hrs after 5 Gy or higher, and by 24 hrs after 1 Gy or higher. This increased release was accompanied by a radiation dose-dependent decrease in {sup 51}Cr and LDH, and an increase in PLA activity in the lysate of cells adherent to the monolayer at 24 hrs. The continuous presence of cAMP from 1 hr before to 24 hrs after irradiation reduced all of these radiation reactions, although mM concentrations of cAMP were required for significant sparing. The presence of cAMP from 1 hr before to 10 min after irradiation had no effect on BAEC sensitivity, whereas cAMP added 10 min after irradiation was fully as effective as continuously administered drug. Thus, cultured BAEC exhibit membrane dysfunction within 24 hrs after clinically relevant radiation doses, and this dysfunction is ameliorated by cAMP present after irradiation.

  12. Radiosensitivity of Human Fibroblasts is Associated With Amino Acid Substitution Variants in Susceptible Genes And Correlates With The Number of Risk Alleles

    SciTech Connect

    Alsbeih, Ghazi . E-mail: galsbeih@kfshrc.edu.sa; El-Sebaie, Medhat; Al-Harbi, Najla; Al-Buhairi, Muneera; Al-Hadyan, Khaled; Al-Rajhi, Nasser

    2007-05-01

    Purpose: Genetic predictive markers of radiosensitivity are being sought for stratifying radiotherapy for cancer patients and risk assessment of radiation exposure. We hypothesized that single nucleotide polymorphisms in susceptible genes are associated with, and the number of risk alleles has incremental effect on, individual radiosensitivity. Methods and Materials: Six amino acid substitution variants (ATM 1853 Asp/Asn G>A, p53 72 Arg/Pro G>C, p21 31 Ser/Arg C>A, XRCC1 399 Arg/Gln G>A, XRCC3 241 Thr/Met C>T, and TGF{beta}1 10 Leu/Pro T>C) were genotyped by direct sequencing in 54 fibroblast strains of different radiosensitivity. Results: The clonogenic survival fraction at 2 Gy range was 0.15-0.50 (mean, 0.34, standard deviation, 0.08). The mean survival fraction at 2 Gy divided the cell strains into radiosensitive (26 cases) and normal (28 controls). A significant association was observed between the survival fraction at 2 Gy and ATM 1853 Asn, XRCC3 241 Met, and TGF{beta}1 10 Leu alleles (p = 0.05, p = 0.02, and p = 0.02, respectively). The p53 72 Arg allele showed a borderline association (p = 0.07). The number of risk alleles increased with increasing radiosensitivity, and the group comparison showed a statistically significant difference between the radiosensitive and control groups (p {<=}0.001). Conclusion: The results of our study have shown that single nucleotide polymorphisms in susceptible genes influence cellular radiation response and that the number of risk alleles has a combined effect on radiosensitivity. Individuals with multiple risk alleles could be more susceptible to radiation effects than those with fewer risk alleles. These results may have implications in predicting normal tissue reactions to radiotherapy and risk assessment of radiation exposure.

  13. Phenotypic Screening Identifies Protein Synthesis Inhibitors as H-Ras-Nanocluster-Increasing Tumor Growth Inducers.

    PubMed

    Najumudeen, Arafath K; Posada, Itziar M D; Lectez, Benoit; Zhou, Yong; Landor, Sebastian K-J; Fallarero, Adyary; Vuorela, Pia; Hancock, John; Abankwa, Daniel

    2015-12-15

    Ras isoforms H-, N-, and K-ras are each mutated in specific cancer types at varying frequencies and have different activities in cell fate control. On the plasma membrane, Ras proteins are laterally segregated into isoform-specific nanoscale signaling hubs, termed nanoclusters. As Ras nanoclusters are required for Ras signaling, chemical modulators of nanoclusters represent ideal candidates for the specific modulation of Ras activity in cancer drug development. We therefore conducted a chemical screen with commercial and in-house natural product libraries using a cell-based H-ras-nanoclustering FRET assay. Next to established Ras inhibitors, such as a statin and farnesyl-transferase inhibitor, we surprisingly identified five protein synthesis inhibitors as positive regulators. Using commonly employed cycloheximide as a representative compound, we show that protein synthesis inhibition increased nanoclustering and effector recruitment specifically of active H-ras but not of K-ras. Consistent with these data, cycloheximide treatment activated both Erk and Akt kinases and specifically promoted H-rasG12V-induced, but not K-rasG12V-induced, PC12 cell differentiation. Intriguingly, cycloheximide increased the number of mammospheres, which are enriched for cancer stem cells. Depletion of H-ras in combination with cycloheximide significantly reduced mammosphere formation, suggesting an exquisite synthetic lethality. The potential of cycloheximide to promote tumor cell growth was also reflected in its ability to increase breast cancer cell tumors grown in ovo. These results illustrate the possibility of identifying Ras-isoform-specific modulators using nanocluster-directed screening. They also suggest an unexpected feedback from protein synthesis inhibition to Ras signaling, which might present a vulnerability in certain tumor cell types. PMID:26568031

  14. Retention of the In Vitro Radiosensitizing Potential of Gemcitabine Under Anoxic Conditions, in p53 Wild-Type and p53-Deficient Non-Small-Cell Lung Carcinoma Cells

    SciTech Connect

    Wouters, An; Pauwels, Bea; Lambrechts, Hilde A.J.; Pattyn, Greet G.O.; Ides, Johan; Baay, Marc; Meijnders, Paul; Peeters, Marc; Vermorken, Jan B.; Lardon, Filip

    2011-06-01

    Purpose: Whereas radiosensitization by gemcitabine is well studied under normal oxygen conditions, little is known about its radiosensitizing potential under reduced oxygen conditions. Therefore, the present study evaluated the impact of anoxia on gemcitabine-mediated radiosensitization. Methods and Materials: The clonogenic assay was performed in three isogenic A549 cell lines differing in p53 status (24 h, 0-15 nM gemcitabine, 0-8 Gy irradiation, normoxia vs. anoxia). Using radiosensitizing conditions, cells were collected for cell cycle analysis and apoptosis detection. Results: Whereas wild-type p53 A549-LXSN cells were more sensitive to radiation than p53-deficient A549-E6 cells, both cell lines showed similar radiosensitization by gemcitabine under normoxia and anoxia. Independent of p53 functionality, gemcitabine was able to overcome anoxia-induced G{sub 0/1} arrest and established an (early) S phase block in normoxic and anoxic cells. The percentage early and late apoptotic/necrotic cells increased with the gemcitabine/radiation combination, with a significant difference between A549-LXSN and A549-E6. Conclusions: This study is the first to show that gemcitabine retains its radiosensitizing potential under low oxygen conditions. Although radiosensitization was observed in both p53 wild-type and p53-deficient cells, p53 status might influence induction of apoptosis after gemcitabine/radiation treatment, whereas no effect on cell cycle progression was noticed.

  15. Chemosensitization and radiosensitization of a lung cancer cell line A549 induced by a composite polymer micelle.

    PubMed

    Xu, Jing; Zhang, Bi-Cheng; Li, Xiang-Long; Xu, Wen-Hong; Zhou, Juan; Shen, Li; Wei, Qi-Chun

    2016-08-01

    Multidrug resistance (MDR) to Doxorubicin (DOX) remains a major obstacle to successful cancer treatment. The present study sought to overcome the MDR of lung cancer cells and achieve radiosensitization by developing a composite DOX-loaded micelle (M-DOX). M-DOX containing PEG-PCL/Pluronic P105 was prepared by the solvent evaporation method. Lung cancer cell line A549 was adopted in this study. In vitro cytotoxicity, cellular uptake behavior, subcellular distribution, and radiosensitivity were evaluated by the treatment with M-DOX, and free DOX was used as a control. A549 cells treated with M-DOX as opposed to free DOX showed greater cellular uptake as well as greater cytotoxicity. Furthermore, M-DOX reached the mitochondria and lysosome effectively after cellular uptake, and fluorescence used to track M-DOX was found to be surrounding the nucleus. Finally, colony-forming assays demonstrated that M-DOX treatment improved radiosensitization when compared to free DOX. Based on the increased cytotoxicity and radiosensitization, M-DOX could be considered as a promising drug delivery system to overcome MDR in lung cancer therapy. PMID:27585226

  16. Dose-rate dependence of heat radiosensitization

    SciTech Connect

    Gerner, E.W.; Oval, J.H.; Manning, M.R.; Sim, D.A.; Bowden, G.T.; Hevezi, J.M.

    1983-09-01

    The dose rate dependence of heat radiosensitization was studied using rat astrocytoma cells in culture and a cliniclly relevant protocol of heat dose and heat radiation sequence. Cells were treated with a minimally toxic heat dose of 43/sup 0/C for 30 minutes, after which they were irradiated with varying doses of radiation at dose rates ranging from 0.567 to 300 cGy/min. This heat dose substantially reduced the extrapolation number (n), but had little effect on D/sub 0/ of the radiation survival curve at dose rates of 50 cGy/min or greater. At dose rates less than 10 cGy/min, 43/sup 0/C for 30 min had little effect on n and only for the lowest dose rate studied (0.567 cGy/min) was there a significant reduction in D/sub 0/ (60%). The thermal enhancement ratio did not vary inversely with radiation dose rate over the dose rate range studied but, instead, was maximal at the two dose rate extremes (0.567 and 300 cGy/min). These data demonstrate that a clinically relevant heat dose enhances very low dose rate, as well as high dose rate, ionizing radiation, but suggest that little benefit is to be gained from using dose rates intermediate between conventional radiotherapeutic high dose rates or dose rates representative of interstitial implants.

  17. Melanoma cells show a heterogeneous range of sensitivity to ionizing radiation and are radiosensitized by inhibition of B-RAF with PLX-4032

    PubMed Central

    Sambade, Maria J.; Peters, Eldon C.; Thomas, Nancy E.; Kaufmann, William K.; Kimple, Randall J.; Shields, Janiel M.

    2011-01-01

    Purpose To assess the relative radiosensitivities of a large collection of melanoma cell lines and to determine whether pharmacologic inhibition of mutant B-RAF with PLX-4032 can radiosensitize B-Raf+ melanoma cells. Methods and Materials A large collection of melanoma cell lines (n=37) were treated with 0 – 8 Gy IR and clonogenic survival assays used to generate survival curves to rank relative radiosensitivities among the cell lines. The ability of a B-RAF inhibitor, PLX-4032, to radiosensitize highly radioresistant, B-Raf+ cells was also assessed by clonogenic cell survival and spheroid invasion assays and the effects of treatment on the cell cycle assessed by FACS. Results Melanoma cell lines displayed a very large, heterogeneous range of SF2 values (1.002 – 0.053) with a mean of 0.51. Cell lines with surviving fractions of 0.29 or less at SF2 and SF4 were observed at a high frequency of 18.9% and 70.2%, respectively. Treatment of B-Raf+ cells with the B-RAF inhibitor PLX-4032 in combination with radiation provided enhanced inhibition of both colony formation and invasion, and radiosensitized cells through an increase in G1 arrest. Conclusions Our data suggest that melanomas are not uniformly radioresistant with a significant subset displaying inherent radiosensitivity. Pharmacologic inhibition of B-RAF with PLX-4032 effectively radiosensitized B-Raf+ melanoma cells suggesting this combination approach could provide improved radiotherapeutic response in B-Raf+ melanoma patients. PMID:21295875

  18. Celecoxib Induced Tumor Cell Radiosensitization by Inhibiting Radiation Induced Nuclear EGFR Transport and DNA-Repair: A COX-2 Independent Mechanism

    SciTech Connect

    Dittmann, Klaus H. Mayer, Claus; Ohneseit, Petra A.; Raju, Uma; Andratschke, Nickolaus H.; Milas, Luka; Rodemann, H. Peter

    2008-01-01

    Purpose: The purpose of the study was to elucidate the molecular mechanisms mediating radiosensitization of human tumor cells by the selective cyclooxygenase (COX)-2 inhibitor celecoxib. Methods and Materials: Experiments were performed using bronchial carcinoma cells A549, transformed fibroblasts HH4dd, the FaDu head-and-neck tumor cells, the colon carcinoma cells HCT116, and normal fibroblasts HSF7. Effects of celecoxib treatment were assessed by clonogenic cell survival, Western analysis, and quantification of residual DNA damage by {gamma}H{sub 2}AX foci assay. Results: Celecoxib treatment resulted in a pronounced radiosensitization of A549, HCT116, and HSF7 cells, whereas FaDu and HH4dd cells were not radiosensitized. The observed radiosensitization could neither be correlated with basal COX-2 expression pattern nor with basal production of prostaglandin E2, but was depended on the ability of celecoxib to inhibit basal and radiation-induced nuclear transport of epidermal growth factor receptor (EGFR). The nuclear EGFR transport was strongly inhibited in A549-, HSF7-, and COX-2-deficient HCT116 cells, which were radiosensitized, but not in FaDu and HH4dd cells, which resisted celecoxib-induced radiosensitization. Celecoxib inhibited radiation-induced DNA-PK activation in A549, HSF7, and HCT116 cells, but not in FaDu and HH4dd cells. Consequentially, celecoxib increased residual {gamma}H2AX foci after irradiation, demonstrating that inhibition of DNA repair has occurred in responsive A549, HCT116, and HSF7 cells only. Conclusions: Celecoxib enhanced radiosensitivity by inhibition of EGFR-mediated mechanisms of radioresistance, a signaling that was independent of COX-2 activity. This novel observation may have therapeutic implications such that COX-2 inhibitors may improve therapeutic efficacy of radiation even in patients whose tumor radioresistance is not dependent on COX-2.

  19. Clonal cell populations unresponsive to radiosensitization induced by telomerase inhibition

    SciTech Connect

    Ju, Yeun-Jin; Shin, Hyun-Jin; Park, Jeong-Eun; Juhn, Kyoung-Mi; Woo, Seon Rang; Kim, Hee-Young; Han, Young-Hoon; Hwang, Sang-Gu; Hong, Sung-Hee; Kang, Chang-Mo; Yoo, Young-Do; Park, Won-Bong; Cho, Myung-Haing; Park, Gil Hong; Lee, Kee-Ho

    2010-11-12

    Research highlights: {yields} In our present manuscript, we have clearly showed an interesting but problematic obstacle of a radiosensitization strategy based on telomerase inhibition by showing that: Clonal population unresponsive to this radiosensitization occasionally arise. {yields} The telomere length of unsensitized clones was reduced, as was that of most sensitized clones. {yields} The unsensitized clones did not show chromosome end fusion which was noted in all sensitized clones. {yields} P53 status is not associated with the occurrence of unsensitized clone. {yields} Telomere end capping in unsensitized clone is operative even under telomerase deficiency. -- Abstract: A combination of a radiotherapeutic regimen with telomerase inhibition is valuable when tumor cells are to be sensitized to radiation. Here, we describe cell clones unresponsive to radiosensitization after telomere shortening. After extensive division of individual transformed clones of mTERC{sup -/-} cells, about 22% of clones were unresponsive to radiosensitization even though telomerase action was inhibited. The telomere lengths of unsensitized mTERC{sup -/-} clones were reduced, as were those of most sensitized clones. However, the unsensitized clones did not exhibit chromosomal end-to-end fusion to the extent noted in all sensitized clones. Thus, a defense mechanism preventing telomere erosion is operative even when telomeres become shorter under conditions of telomerase deficiency, and results in unresponsiveness to the radiosensitization generally mediated by telomere shortening.

  20. Targeted Radiosensitization by the Chk1 Inhibitor SAR-020106

    SciTech Connect

    Borst, Gerben R.; McLaughlin, Martin; Kyula, Joan N.; Neijenhuis, Sari; Khan, Aadil; Good, James; Zaidi, Shane; Powell, Ned G.; Meier, Pascal; Collins, Ian; Garrett, Michelle D.; Verheij, Marcel; Harrington, Kevin J.

    2013-03-15

    Purpose: To explore the activity of a potent Chk1 inhibitor (SAR-020106) in combination with radiation. Methods and Materials: Colony and mechanistic in vitro assays and a xenograft in vivo model. Results: SAR-020106 suppressed-radiation-induced G{sub 2}/M arrest and reduced clonogenic survival only in p53-deficient tumor cells. SAR-020106 promoted mitotic entry following irradiation in all cell lines, but p53-deficient cells were likely to undergo apoptosis or become aneuploid, while p53 wild-type cells underwent a postmitotic G{sub 1} arrest followed by subsequent normal cell cycle re-entry. Following combined treatment with SAR-020106 and radiation, homologous-recombination-mediated DNA damage repair was inhibited in all cell lines. A significant increase in the number of pan-γH2AX-staining apoptotic cells was observed only in p53-deficient cell lines. Efficacy was confirmed in vivo in a clinically relevant human head-and-neck cell carcinoma xenograft model. Conclusion: The Chk1 inhibitor SAR-020106 is a potent radiosensitizer in tumor cell lines defective in p53 signaling.

  1. Correlation between radiosensitivity, percentage hypoxic cells and pO2 measurements in one rodent and two human tumor xenografts.

    PubMed

    Thomas, C D; Chavaudra, N; Martin, L; Guichard, M

    1994-07-01

    Computerized pO2 histography has been used to measure the intratumor pO2 in patients for the past few years, and there is now evidence that these tumors contain hypoxic cells. One of the major questions that remains to be answered is the relevance of such data to radiosensitivity. The present study looks for a correlation between intratumor pO2, the percentage of hypoxic cells in the tumor and the radiosensitization induced by carbogen and/or the oxygen carrier, perflubron emulsion. Two human tumor xenografts (HRT18, Na11+) and one rodent tumor (EMT6) were used. The radiosensitivity (clonogenic assay) and the oxygen tension (computerized pO2 histography) were measured. All experiments were performed under similar conditions. Carbogen increased tumor radiosensitivity; sensitization was greatest when 4 ml/kg perflubron emulsion was used in conjunction with carbogen. The pO2 distribution was shifted to higher pO2 values in the tumors whatever the treatment; the shift was greater for perflubron emulsion plus carbogen. The low pO2 values (< 0.4 kPa) were lost for the HRT18 cells. A correlation (EMT6, HRT18) or a link (Na11+) between the radiosensitization and the oxygen tension measurements was found for values below 1.07 or 1.33 kPa. A trend between the percentage of hypoxic cells and pO2 measurements was found taking into account pO2 measurements comprised between 0.27 and 0.67 kPa. PMID:8016297

  2. Homologous recombination as a potential target for caffeine radiosensitization in mammalian cells: reduced caffeine radiosensitization in XRCC2 and XRCC3 mutants

    NASA Technical Reports Server (NTRS)

    Asaad, N. A.; Zeng, Z. C.; Guan, J.; Thacker, J.; Iliakis, G.

    2000-01-01

    The radiosensitizing effect of caffeine has been associated with the disruption of multiple DNA damage-responsive cell cycle checkpoints, but several lines of evidence also implicate inhibition of DNA repair. The role of DNA repair inhibition in caffeine radiosensitization remains uncharacterized, and it is unknown which repair process, or lesion, is affected. We show that a radiosensitive cell line, mutant for the RAD51 homolog XRCC2 and defective in homologous recombination repair (HRR), displays significantly diminished caffeine radiosensitization that can be restored by expression of XRCC2. Despite the reduced radiosensitization, caffeine effectively abrogates checkpoints in S and G2 phases in XRCC2 mutant cells indicating that checkpoint abrogation is not sufficient for radiosensitization. Another radiosensitive line, mutant for XRCC3 and defective in HRR, similarly shows reduced caffeine radiosensitization. On the other hand, a radiosensitive mutant (irs-20) of DNA-PKcs with a defect in non-homologous end-joining (NHEJ) is radiosensitized by caffeine to an extent comparable to wild-type cells. In addition, rejoining of radiation-induced DNA DSBs, that mainly reflects NHEJ, remains unaffected by caffeine in XRCC2 and XRCC3 mutants, or their wild-type counterparts. These observations suggest that caffeine targets steps in HRR but not in NHEJ and that abrogation of checkpoint response is not sufficient to explain radiosensitization. Indeed, immortalized fibroblasts from AT patients show caffeine radiosensitization despite the checkpoint defects associated with ATM mutation. We propose that caffeine radiosensitization is mediated by inhibition of stages in DNA DSB repair requiring HRR and that checkpoint disruption contributes by allowing these DSBs to transit into irreparable states. Thus, checkpoints may contribute to genomic stability by promoting error-free HRR.

  3. Coculture with astrocytes reduces the radiosensitivity of glioblastoma stem-like cells and identifies additional targets for radiosensitization

    PubMed Central

    Rath, Barbara H; Wahba, Amy; Camphausen, Kevin; Tofilon, Philip J

    2015-01-01

    Toward developing a model system for investigating the role of the microenvironment in the radioresistance of glioblastoma (GBM), human glioblastoma stem-like cells (GSCs) were grown in coculture with human astrocytes. Using a trans-well assay, survival analyses showed that astrocytes significantly decreased the radiosensitivity of GSCs compared to standard culture conditions. In addition, when irradiated in coculture, the initial level of radiation-induced γH2AX foci in GSCs was reduced and foci dispersal was enhanced suggesting that the presence of astrocytes influenced the induction and repair of DNA double-strand breaks. These data indicate that astrocytes can decrease the radiosensitivity of GSCs in vitro via a paracrine-based mechanism and further support a role for the microenvironment as a determinant of GBM radioresponse. Chemokine profiling of coculture media identified a number of bioactive molecules not present under standard culture conditions. The gene expression profiles of GSCs grown in coculture were significantly different as compared to GSCs grown alone. These analyses were consistent with an astrocyte-mediated modification in GSC phenotype and, moreover, suggested a number of potential targets for GSC radiosensitization that were unique to coculture conditions. Along these lines, STAT3 was activated in GSCs grown with astrocytes; the JAK/STAT3 inhibitor WP1066 enhanced the radiosensitivity of GSCs under coculture conditions and when grown as orthotopic xenografts. Further, this coculture system may also provide an approach for identifying additional targets for GBM radiosensitization. PMID:26518290

  4. Development of a Novel Enzyme-Targeting Radiosensitizer (New KORTUC) Using a Gelatin-Based Hydrogel Instead of a Sodium Hyaluronate

    PubMed Central

    Morita-Tokuhiro, Shiho; Ogawa, Yasuhiro; Yokota, Norikazu; Tsuzuki, Akira; Oda, Hideki; Ishida, Naoya; Aoyama, Nobutaka; Nishioka, Akihito

    2016-01-01

    We recently developed Kochi Oxydol-Radiation Therapy for Unresectable Carcinomas (KORTUC) as a strategy to increase intratumoral oxygen concentrations and degrade antioxidant enzymes such as peroxidase and catalase. We then developed KORTUC II, which uses sodium hyaluronate containing hydrogen peroxide as a radiosensitizer. KORTUC II requires twice-weekly administration to sustain its effects, but decreasing the frequency of radiosensitizer injections to once-weekly would reduce the burden on the patients and the physicians. The goal of this study was thus to develop a new formulation of KORTUC (New KORTUC) that only requires once-weekly administration. We performed experimental studies using a mouse tumor model and biodegradable hydrogel. C3H/He mice were allocated to control, KORTUC, or hydrogel groups. At 72 h after injection, each tumor was irradiated with a 6 MeV electron beam to a total dose of 30 Gy. During a 62-day observation period, changes in tumor volume and survival rates were assessed in each group. Tumor growth rate was slowest in the hydrogel groups. These data suggest that hydrogel could represent a useful adjunct as a long-acting radiosensitizer in place of sodium hyaluronate. New KORTUC, which contains hydrogen peroxide and hydrogel, exerted a radiosensitizing effect that persisted beyond 72 h following injection of the agent. Use of this new formulation allows radiosensitizer injections to be performed once-weekly with good effect. PMID:26751477

  5. Knocking Down Nucleolin Expression Enhances the Radiosensitivity of Non-Small Cell Lung Cancer by Influencing DNA-PKcs Activity.

    PubMed

    Xu, Jian-Yu; Lu, Shan; Xu, Xiang-Ying; Hu, Song-Liu; Li, Bin; Qi, Rui-Xue; Chen, Lin; Chang, Joe Y

    2015-01-01

    Nucleolin (C23) is an important anti-apoptotic protein that is ubiquitously expressed in exponentially growing eukaryotic cells. In order to understand the impact of C23 in radiation therapy, we attempted to investigate the relationship of C23 expression with the radiosensitivity of human non-small cell lung cancer (NSCLC) cells. We investigated the role of C23 in activating the catalytic subunit of DNA-dependent protein kinase (DNA- PKcs), which is a critical protein for DNA double-strand breaks (DSBs) repair. As a result, we found that the expression of C23 was negatively correlated with the radiosensitivity of NSCLC cell lines. In vitro clonogenic survival assays revealed that C23 knockdown increased the radiosensitivity of a human lung adenocarcinoma cell line, potentially through the promotion of radiation-induced apoptosis and adjusting the cell cycle to a more radiosensitive stage. Immunofluorescence data revealed an increasing quantity of γ-H2AX foci and decreasing radiation-induced DNA damage repair following knockdown of C23. To further clarify the mechanism of C23 in DNA DSBs repair, we detected the expression of DNA-PKcs and C23 proteins in NSCLC cell lines. C23 might participate in DNA DSBs repair for the reason that the expression of DNA-PKcs decreased at 30, 60, 120 and 360 minutes after irradiation in C23 knockdown cells. Especially, the activity of DNA-PKcs phosphorylation sites at the S2056 and T2609 was significantly suppressed. Therefore we concluded that C23 knockdown can inhibit DNA-PKcs phosphorylation activity at the S2056 and T2609 sites, thus reducing the radiation damage repair and increasing the radiosensitivity of NSCLC cells. Taken together, the inhibition of C23 expression was shown to increase the radiosensitivity of NSCLC cells, as implied by the relevance to the notably decreased DNA-PKcs phosphorylation activity at the S2056 and T2609 clusters. Further research on targeted C23 treatment may promote effectiveness of radiotherapy

  6. The long non-coding RNA HOTAIR affects the radiosensitivity of pancreatic ductal adenocarcinoma by regulating the expression of Wnt inhibitory factor 1.

    PubMed

    Jiang, Yanhui; Li, Zhihua; Zheng, Shangyou; Chen, Huimou; Zhao, Xiaohui; Gao, Wenchao; Bi, Zhuofei; You, Kaiyun; Wang, Yingxue; Li, Wenzhu; Li, Liting; Liu, Yimin; Chen, Rufu

    2016-03-01

    Pancreatic ductal adenocarcinoma (PDAC) is seriously resistant to radiotherapy and the mechanism is largely unknown. HOX transcript antisense intergenic RNA (HOTAIR) is overexpressed in PDAC. However, the function of HOTAIR has never been related to the radiosensitivity of PDAC. In this present study, the expression of HOTAIR in the PDAC cell lines and tissues was measured by quantitative real-time PCR (qRT-PCR), and the association between HOTAIR expression levels and X-ray treatment in PDAC cell lines was investigated. Additionally, the influence of HOTAIR knockdown on radiosensitivity, proliferation, and apoptosis of PDAC cells after radiation was evaluated by colony formation assays, Cell Counting Kit-8 (CCK-8) assays, and flow cytometry, respectively. Furthermore, the correlation between HOTAIR and Wnt inhibitory factor 1 (WIF-1) expression in PDAC cell lines and tissues was studied to assess the role of HOTAIR and WIF-1 in the radiosensitivity of PDAC. The results confirmed that HOTAIR expression was significantly increased in the PDAC cell lines and tissues (n = 90) compared with human normal pancreatic ductal epithelial cell line (HPDE) and matched adjacent normal tissues (n = 90). Functionally, HOTAIR knockdown enhanced the radiosensitivity of PDAC cells, reduced the proliferation, and increased the apoptosis of cells after radiation. And HOTAIR silencing increased the expression of WIF-1. Furthermore, the overexpression of WIF-1 revealed that HOTAIR modulated the radiosensitivity of PDAC cells by regulating the expression of WIF-1. These data reveals that HOTAIR can affect the radiosensitivity of PDAC cells partly via regulating the expression of WIF-1, and HOTAIR-WIF-1 axis is a potential target for PDAC radiotherapy. PMID:26482614

  7. Can Drugs Enhance Hypofractionated Radiotherapy? A Novel Method of Modeling Radiosensitization Using In Vitro Data

    SciTech Connect

    Ohri, Nitin; Dicker, Adam P.; Lawrence, Yaacov Richard

    2012-05-01

    Purpose: Hypofractionated radiotherapy (hRT) is being explored for a number of malignancies. The potential benefit of giving concurrent chemotherapy with hRT is not known. We sought to predict the effects of combined modality treatments by using mathematical models derived from laboratory data. Methods and Materials: Data from 26 published clonogenic survival assays for cancer cell lines with and without the use of radiosensitizing chemotherapy were collected. The first three data points of the RT arm of each assay were used to derive parameters for the linear quadratic (LQ) model, the multitarget (MT) model, and the generalized linear quadratic (gLQ) model. For each assay and model, the difference between the predicted and observed surviving fractions at the highest tested RT dose was calculated. The gLQ model was fitted to all the data from each RT cell survival assay, and the biologically equivalent doses in 2-Gy fractions (EQD2s) of clinically relevant hRT regimens were calculated. The increase in cell kill conferred by the addition of chemotherapy was used to estimate the EQD2 of hRT along with a radiosensitizing agent. For comparison, this was repeated using conventionally fractionated RT regimens. Results: At a mean RT dose of 8.0 Gy, the average errors for the LQ, MT, and gLQ models were 1.63, 0.83, and 0.56 log units, respectively, favoring the gLQ model (p < 0.05). Radiosensitizing chemotherapy increased the EQD2 of hRT schedules by an average of 28% to 82%, depending on disease site. This increase was similar to the gains predicted for the addition of chemotherapy to conventionally fractionated RT. Conclusions: Based on published in vitro assays, the gLQ equation is superior to the LQ and MT models in predicting cell kill at high doses of RT. Modeling exercises demonstrate that significant increases in biologically equivalent dose may be achieved with the addition of radiosensitizing agents to hRT. Clinical study of this approach is warranted.

  8. [Optimization and Prognosis of Cell Radiosensitivity Enhancement in vitro and in vivo after Sequential Thermoradiactive Action].

    PubMed

    Belkina, S V; Petin, V G

    2016-01-01

    Previously developed mathematical model of simultaneous action of two inactivating agents has been adapted and tested to describe the results of sequential action. The possibility of applying the mathematical model to the interpretation and prognosis of the increase in radio-sensitivity of tumor cells as well as mammalian cells after sequential action of two high temperatures or hyperthermia and ionizing radiation is analyzed. The model predicts the value of the thermal enhancement ratio depending on the duration of thermal exposure, its greatest value, and the condition under which it is achieved. PMID:27534067

  9. Radiosensitivity in HeLa cervical cancer cells overexpressing glutathione S-transferase π 1

    PubMed Central

    YANG, LIANG; LIU, REN; MA, HONG-BIN; YING, MING-ZHEN; WANG, YA-JIE

    2015-01-01

    The aims of the present study were to investigate the effect of overexpressed exogenous glutathione S-transferase π 1 (GSTP1) gene on the radiosensitivity of the HeLa human cervical cancer cell line and conduct a preliminarily investigation into the underlying mechanisms of the effect. The full-length sequence of human GSTP1 was obtained by performing a polymerase chain reaction (PCR) using primers based on the GenBank sequence of GSTP1. Subsequently, the gene was cloned into a recombinant eukaryotic expression plasmid, and the resulting construct was confirmed by restriction analysis and DNA sequencing. A HeLa cell line that was stably expressing high levels of GSTP1 was obtained through stable transfection of the constructed plasmids using lipofectamine and screening for G418 resistance, as demonstrated by reverse transcription-PCR. Using the transfected HeLa cells, a colony formation assay was conducted to detect the influence of GSTP1 overexpression on the cell radiosensitivity. Furthermore, flow cytometry was used to investigate the effect of GSTP1 overexpression on cell cycle progression, with the protein expression levels of the cell cycle regulating factor cyclin B1 detected using western blot analysis. Colony formation and G2/M phase arrest in the GSTP1-expressing cells were significantly increased compared with the control group (P<0.01). In addition, the expression of cyclin B1 was significantly reduced in the GSTP1-expressing cells. These results demonstrated that increased expression of GSTP1 inhibits radiosensitivity in HeLa cells. The mechanism underlying this effect may be associated with the ability of the GSTP1 protein to reduce cyclin B1 expression, resulting in significant G2/M phase arrest. PMID:26622693

  10. Radiosensitizing activity and pharmacokinetics of multiple dose administered KU-2285 in peripheral nerve tissue in mice

    SciTech Connect

    Iwai, Hiroyuki; Matsuno, Etsuko ); Sasai, Keisuke; Abe, Mitsuyuki; Shibamoto, Yuta )

    1994-06-15

    In a clinical trial in which a 2-nitroimidazole radiosensitizer was administered repeatedly, the dose-limiting toxicity was found to be peripheral neuropathy. In the present study, the in vivo radiosensitizing activity of KU-2285 in combination with radiation dose fractionation, and the pharmacokinetics of cumulative dosing of KU-2285 in the peripheral nerves were examined. The ability of three nitroimidazoles, misonidazole (MISO), etanidazole (SR-2508) and KU-2285, to sensitize SCCVII tumors to radiation treatment has been compared for drug doses in the range 0-200 mg/kg. Single radiation doses or two different fractionation schedules (6 Gy/fractions [times] three fractions/48 h or 5 Gy/fractions [times] five fractions/48 h) were used; the tumor cell survival was determined using an in vivo/in vitro colony assay. The pharmacokinetics in the sciatic nerves were undertaken, when KU-2285 or etanidazole were injected at a dose of 200 mg/kg intravenously one, two, three, or four times at 2-h intervals. At less than 100 mg/kg, KU-2285 sensitized SCCVII tumors more than MISO and SR-2508 by fractionated irradiation. Evaluation of pharmacokinetics in the peripheral nerves showed that the apparent biological half-life of SR-2508 increased with the increases in the number of administrations, whereas that of KU-2285 became shorter. Since most clinical radiotherapy is given in small multiple fractions, KU-2285 appears to be a hypoxic cell radiosensitizer that could be useful in such regimens, and that poses no risk of chronic peripheral neurotoxicity. 12 refs., 5 figs., 1 tab.

  11. Hedgehog Pathway Inhibition Radiosensitizes Non-Small Cell Lung Cancers

    PubMed Central

    Zeng, Jing; Aziz, Khaled; Chettiar, Sivarajan T.; Aftab, Blake T.; Armour, Michael; Gajula, Rajendra; Gandhi, Nishant; Salih, Tarek; Herman, Joseph M.; Wong, John; Rudin, Charles M.; Tran, Phuoc T.; Hales, Russell K.

    2012-01-01

    Purpose Despite improvements in chemoradiation, local control remains a major clinical problem in locally advanced non-small cell lung cancer. The Hedgehog pathway has been implicated in tumor recurrence by promoting survival of tumorigenic precursors and through effects on tumor-associated stroma. Whether Hedgehog inhibition can affect radiation efficacy in vivo has not been reported. Methods and Materials We evaluated the effects of a targeted Hedgehog inhibitor (HhAntag) and radiation on clonogenic survival of human non-small cell lung cancer lines in vitro. Using an A549 cell line xenograft model, we examined tumor growth, proliferation, apoptosis, and gene expression changes after concomitant HhAntag and radiation. In a transgenic mouse model of KrasG12D-induced and Twist1-induced lung adenocarcinoma, we assessed tumor response to radiation and HhAntag by serial micro-computed tomography (CT) scanning. Results In 4 human lung cancer lines in vitro, HhAntag showed little or no effect on radio-sensitivity. By contrast, in both the human tumor xenograft and murine inducible transgenic models, HhAntag enhanced radiation efficacy and delayed tumor growth. By use of the human xenograft model to differentiate tumor and stromal effects, mouse stromal cells, but not human tumor cells, showed significant and consistent downregulation of Hedgehog pathway gene expression. This was associated with increased tumor cell apoptosis. Conclusions Targeted Hedgehog pathway inhibition can increase in vivo radiation efficacy in lung cancer preclinical models. This effect is associated with pathway suppression in tumor-associated stroma. These data support clinical testing of Hedgehog inhibitors as a component of multimodality therapy for locally advanced non-small cell lung cancer. PMID:23182391

  12. Hedgehog Pathway Inhibition Radiosensitizes Non-Small Cell Lung Cancers

    SciTech Connect

    Zeng, Jing; Aziz, Khaled; Chettiar, Sivarajan T.; Aftab, Blake T.; Armour, Michael; Gajula, Rajendra; Gandhi, Nishant; Salih, Tarek; Herman, Joseph M.; Wong, John; Rudin, Charles M.; Tran, Phuoc T.; Hales, Russell K.

    2013-05-01

    Purpose: Despite improvements in chemoradiation, local control remains a major clinical problem in locally advanced non-small cell lung cancer. The Hedgehog pathway has been implicated in tumor recurrence by promoting survival of tumorigenic precursors and through effects on tumor-associated stroma. Whether Hedgehog inhibition can affect radiation efficacy in vivo has not been reported. Methods and Materials: We evaluated the effects of a targeted Hedgehog inhibitor (HhAntag) and radiation on clonogenic survival of human non-small cell lung cancer lines in vitro. Using an A549 cell line xenograft model, we examined tumor growth, proliferation, apoptosis, and gene expression changes after concomitant HhAntag and radiation. In a transgenic mouse model of Kras{sup G12D}-induced and Twist1-induced lung adenocarcinoma, we assessed tumor response to radiation and HhAntag by serial micro-computed tomography (CT) scanning. Results: In 4 human lung cancer lines in vitro, HhAntag showed little or no effect on radiosensitivity. By contrast, in both the human tumor xenograft and murine inducible transgenic models, HhAntag enhanced radiation efficacy and delayed tumor growth. By use of the human xenograft model to differentiate tumor and stromal effects, mouse stromal cells, but not human tumor cells, showed significant and consistent downregulation of Hedgehog pathway gene expression. This was associated with increased tumor cell apoptosis. Conclusions: Targeted Hedgehog pathway inhibition can increase in vivo radiation efficacy in lung cancer preclinical models. This effect is associated with pathway suppression in tumor-associated stroma. These data support clinical testing of Hedgehog inhibitors as a component of multimodality therapy for locally advanced non-small cell lung cancer.

  13. Radiosensitivity of testicular cells in the fetal mouse

    SciTech Connect

    Vergouwen, R.P.F.A.; Roepers-Gajadien, H.L.; Rooij, D.G. de; Huiskamp, R.; Bas, R.J.; Davids, J.A.G.

    1995-01-01

    The effects of prenatal X irradiation on postnatal development of the CBA/P mouse testis was studied. At days 14, 15 and 18 post coitus pregnant female mice were exposed to single doses of X rays ranging from 0.25-1.5 Gy. Higher doses resulted in extensive loss of fetal mice. In the male offspring, at days 3 and 31 post partum, the numbers of gonocytes, type A spermatogonia and Sertoli cells per testis were determined using the disector method. Furthermore, after irradiation at day 15 post coitus, the numbers of Leydig cells, mesenchymal cells, macrophages, myoid cells, lymphatic endothelial cells, endothelial cells and perivascular cells per testis were also determined at days 3 and 31 post partum. At day 3 post partum, the number of germ cells was decreased after irradiation at days 14 and 15 post coitus. A D{sub o} value of 0.7 Gy was determined for the radiosensitivity of the gonocytes at day 14 post coitus. A D{sub o} value of 0.8 Gy was determined for the gonocytes at day 15 post coitus which, however, seems to be less accurate. No accurate D{sub o} value could be determined for the gonocytes at day 18 post coitus. At day 31 post partum, the repopulation of the seminiferous epithelium as well as testis weights and tubular diameters were more affected by irradiation with increasing age of the mice at the time of irradiation. The percentage of tubular cross sections showing spermatids decreased with increasing dose after irradiation at days 15 and 18 post coitus, but not after irradiation at day 14 post coitus. Furthermore, in tubular cross sections showing spermatids, exposure of testes to 1.25 and 1.5 Gy at day 18 post coitus resulted in significantly lower numbers of spermatids per cross section when compared to those testes exposed to the same doses at day 15 post coitus. 30 refs., 7 figs., 1 tab.

  14. Chitooligosaccharides promote radiosensitivity in colon cancer line SW480

    PubMed Central

    Han, Fu-Shi; Yang, Shi-Jie; Lin, Mou-Bin; Chen, Ying-Qun; Yang, Ping; Xu, Jin-Ming

    2016-01-01

    AIM: To investigate the anti-proliferation and radiosensitization effect of chitooligosaccharides (COS) on human colon cancer cell line SW480. METHODS: SW480 cells were treated with 0, 1.0, 2.0, 3.0, 4.0 and 5.0 mg/mL of COS for 48 h. CCK-8 assay was employed to obtain the cell survival ratio of SW480 cells, and the anti-proliferation curve was observed with the inhibition ratio of COS on SW480 cells. The RAY + COS group was treated with 1.0 mg/mL of COS for 48 h, while both the RAY and RAY+COS groups were exposed to X-ray at 0, 1, 2, 4, 6 and 8 Gy, respectively. Clonogenic assay was used to analyze cell viability in the two groups at 10 d after treatment, and a cell survival curve was used to analyze the sensitization ratio of COS. The RAY group was exposed to X-ray at 6 Gy, while the RAY+COS group was treated with 1.0 mg/mL of COS for 48 h in advance and exposed to X-ray at 6 Gy. Flow cytometry was employed to detect cell cycle and apoptosis rate in the non-treatment group, as well as in the RAY and RAY + COS groups after 24 h of treatment. RESULTS: COS inhibited the proliferation of SW480 cells, and the inhibition rate positively correlated with the concentration of COS (P < 0.01). Cell viability decreased as radiation dose increased in the RAY and RAY+COS groups (P < 0.01). Cell viabilities in the RAY+COS group were lower than in the RAY group at all doses of X-ray exposure (P < 0.01), and the sensitization ratio of COS on SW480 cells was 1.39. Compared with the non-treatment group, there was a significant increase in apoptosis rate in both the RAY and RAY + COS groups; while the apoptosis rate in the RAY+COS group was significantly higher than in the RAY group (P < 0.01). In comparing these three groups, the percentage of G2/M phase in both the RAY and RAY + COS groups significantly increased, and the percentage of the S phase and G0/G1 phase was downregulated. Furthermore, the percentage in the G2/M phase was higher, and the percentage in the S phase and G0/G

  15. Biomarkers of Radiosensitivity in A-Bomb Survivors Pregnant at the Time of Bombings in Hiroshima and Nagasaki

    DOE PAGESBeta

    Miles, Edward F.; Tatsukawa, Yoshimi; Funamoto, Sachiyo; Kamada, Naoko; Nakashima, Eiji; Kodama, Yoshiaki; Seed, Thomas; Kusonoki, Yoichiro; Nakachi, Kei; Fujiwara, Saeko; et al

    2011-01-01

    Purpose . There is evidence in the literature of increased maternal radiosensitivity during pregnancy. Materials and Methods . We tested this hypothesis using information from the atomic-bomb survivor cohort, that is, the Adult Health Study database at the Radiation Effects Research Foundation, which contains data from a cohort of women who were pregnant at the time of the bombings of Hiroshima and Nagasaki. Previous evaluation has demonstrated long-term radiation dose-response effects. Results/Conclusions . Data on approximately 250 women were available to assess dose-response rates for serum cholesterol, white blood cell count, erythrocyte sedimentation rate, and serum hemoglobin, and onmore » approximately 85 women for stable chromosome aberrations, glycophorin A locus mutations, and naïve CD4 T-cell counts. Although there is no statistically significant evidence of increased radiosensitivity in pregnant women, the increased slope of the linear trend line in the third trimester with respect to stable chromosome aberrations is suggestive of an increased radiosensitivity.« less

  16. Analysis of individual differences in radiosensitivity using genome editing.

    PubMed

    Matsuura, S; Royba, E; Akutsu, S N; Yanagihara, H; Ochiai, H; Kudo, Y; Tashiro, S; Miyamoto, T

    2016-06-01

    Current standards for radiological protection of the public have been uniformly established. However, individual differences in radiosensitivity are suggested to exist in human populations, which could be caused by nucleotide variants of DNA repair genes. In order to verify if such genetic variants are responsible for individual differences in radiosensitivity, they could be introduced into cultured human cells for evaluation. This strategy would make it possible to analyse the effect of candidate nucleotide variants on individual radiosensitivity, independent of the diverse genetic background. However, efficient gene targeting in cultured human cells is difficult due to the low frequency of homologous recombination (HR) repair. The development of artificial nucleases has enabled efficient HR-mediated genome editing to be performed in cultured human cells. A novel genome editing strategy, 'transcription activator-like effector nuclease (TALEN)-mediated two-step single base pair editing', has been developed, and this was used to introduce a nucleotide variant associated with a chromosomal instability syndrome bi-allelically into cultured human cells to demonstrate that it is the causative mutation. It is proposed that this editing technique will be useful to investigate individual radiosensitivity. PMID:27012844

  17. Neoadjuvant immunotherapy enhances radiosensitivity through natural killer cell activation.

    PubMed

    Chi, Chau-Hwa; Wang, Yu-Shan; Yang, Chieh-Han; Chi, Kwan-Hwa

    2010-02-01

    We investigated whether natural killer (NK) cells in the tumor microenvironment have a radiosensitization effect. The radiosensitization effect of combined CpG and Herceptin((R)) (Genentech, Inc., South San Francisco, CA) (CpG/Herceptin), given before or after radiation, was evaluated by using a murine colon cancer cell line overexpressing human HER2/neu, CT26HER2/neu. In vitro radiosensitization effects were investigated by coculture of CT26HER2/neu with splenocytes, CpG, and Herceptin before applying radiation. Tumor cells, cocultured with CpG-pretreated splenocytes and Herceptin, were more vulnerable to radiation damage. In BALB/c mice injected with CT26HER2/neu, CpG/Herceptin administered before radiotherapy was associated with a better retardation of tumor growth than when administered after radiotherapy. The radiosensitization effect was significantly abrogated by NK-cell depletion, indicating that NK cells play an essential role in it. Further, surviving mice treated with CpG or CpG/Herceptin and reverse transcriptase were resistant to renewed tumor challenge, suggesting the presence of an induced immune response to the tumor. Neoadjuvant immunotherapy with CpG/Herceptin may improve response to radiotherapy of HER2/neu-expressing tumors. PMID:20187795

  18. Histone Deacetylation Critically Determines T-cell Subset Radiosensitivity1

    PubMed Central

    Pugh, Jason L.; Sukhina, Alona S.; Seed, Thomas M.; Manley, Nancy R.; Sempowski, Gregory A.; van den Brink, Marcel R.M.; Smithey, Megan J.; Nikolich-Zugich, Janko

    2014-01-01

    Lymphocytes are sensitive to ionizing radiation and naïve lymphocytes are more radiosensitive than their memory counterparts. Less is known about radiosensitivity of memory cell subsets. We examined the radiosensitivity of naïve (TN), effector memory (TEM), and central memory (TCM) T cell subsets in C57BL/6 mice, and found TEM to be more resistant to radiation-induced apoptosis than either TN or TCM. Surprisingly, we found no correlation between the extent of radiation-induced apoptosis in T cell subsets and : (i) levels of pro- and anti-apoptotic Bcl-2 family members; or (ii) the H2-AX content and maximal γH2-AX fold change. Rather, TEM cell survival correlated with higher levels of immediate γH2-AX marking, immediate break binding and genome-wide open chromatin structure. T cells were able to mark DNA damage seemingly instantly (30 s), even if kept on ice. Relaxing chromatin with the histone deacetylase inhibitor valproic acid following radiation or etoposide treatment, improved the survival of TCM and TN cells up to levels seen in the resistant TEM cells, but did not improve survival from caspase-mediated apoptosis. We conclude that an open genome-wide chromatin state is the key determinant of efficient immediate repair of DNA damage in T cells, explaining the observed T cell subset radiosensitivity differences. PMID:24990082

  19. The Effects of G2-Phase Enrichment and Checkpoint Abrogation on Low-Dose Hyper-Radiosensitivity

    SciTech Connect

    Krueger, Sarah A.; Wilson, George D.; Piasentin, Evano; Joiner, Michael C.; Marples, Brian

    2010-08-01

    Purpose: An association between low-dose hyper-radiosensitivity (HRS) and the 'early' G2/M checkpoint has been established. An improved molecular understanding of the temporal dynamics of this relationship is needed before clinical translation can be considered. This study was conducted to characterize the dose response of the early G2/M checkpoint and then determine whether low-dose radiation sensitivity could be increased by synchronization or chemical inhibition of the cell cycle. Methods and Materials: Two related cell lines with disparate HRS status were used (MR4 and 3.7 cells). A double-thymidine block technique was developed to enrich the G2-phase population. Clonogenic cell survival, radiation-induced G2-phase cell cycle arrest, and deoxyribonucleic acid double-strand break repair were measured in the presence and absence of inhibitors to G2-phase checkpoint proteins. Results: For MR4 cells, the dose required to overcome the HRS response (approximately 0.2 Gy) corresponded with that needed for the activation of the early G2/M checkpoint. As hypothesized, enriching the number of G2-phase cells in the population resulted in an enhanced HRS response, because a greater proportion of radiation-damaged cells evaded the early G2/M checkpoint and entered mitosis with unrepaired deoxyribonucleic acid double-strand breaks. Likewise, abrogation of the checkpoint by inhibition of Chk1 and Chk2 also increased low-dose radiosensitivity. These effects were not evident in 3.7 cells. Conclusions: The data confirm that HRS is linked to the early G2/M checkpoint through the damage response of G2-phase cells. Low-dose radiosensitivity could be increased by manipulating the transition of radiation-damaged G2-phase cells into mitosis. This provides a rationale for combining low-dose radiation therapy with chemical synchronization techniques to improve increased radiosensitivity.

  20. WE-G-BRE-08: Radiosensitization by Olaparib Eluting Nanospheres

    SciTech Connect

    Tangutoori, S; Kumar, R; Sridhar, S; Korideck, H; Makrigiorgos, G; Cormack, R

    2014-06-15

    Purpose: Permanent prostate brachytherapy often uses inert bio-absorbable spacers to achieve the desired geometric distribution of sources within the prostate. Transforming these spacers into implantable nanoplatforms for chemo-radiation therapy (INCeRT) provides a means of providing sustained in-situ release of radiosensitizers in the prostate to enhance the therapeutic ratio of the procedure. Olaparib, a PARP inhibitor, suppresses DNA repair processes present during low dose rate continuous irradiation. This work investigates the radiosensitizing/DNA damage repair inhibition by NanoOlaparib eluting nanospheres. Methods: Human cell line PC3 (from ATCC), was maintained in F12-k medium supplemented with fetal bovine serum. Clonogenic assay kit (from Fischer Scientific) was used to fix and stain the cells to determine the long term effects of irradiation. Nanoparticle size and zeta potential of nanospheres were determined using a Zeta particle size analyzer. The incorporation of Olaparib in nanospheres was evaluated by HPLC. Irradiation was performed in a small animal irradiator operating at 220 KeV.The long term effects of radio-sensitization with olaparib and nanoolaparib was determined using the clonogenic assay at 2 Gy and 4 Gy doses. The cells were allowed to grow for around 10 doubling cycles, The colonies were fixed and stained using clonogenic assay kit. The excess stain was washed off using DI water and the images were taken using a digital camera. Results: Radiosensitization studies were carried out in prostate cancer cell line, PC3 radiation at 0, 2 and 4Gy doses. Strongest dose response was observed with nanoolaparib treated cells compared to untreated cells. Conclusion: A two stage drug release of drug eluting nanospheres from a biodegradable spacer has been suggested for sustained in-situ release of Olaparib to suppress DNA repair processes during prostate brachytherapy. The Olaparib eluting nanospheres had the same in-vitro radiosensitizing effect as

  1. Radiosensitization of EMT6 cells by four platinum complexes.

    PubMed

    Teicher, B A; Rockwell, S; Lee, J B

    1985-05-01

    The greatest research effort in producing radiation sensitizers has been directed toward organic compounds. However, platinum complexes also have radiosensitizing capabilities, perhaps because they bind to DNA. The compound described here are dichloro complexes of bivalent platinum with one or two potentially radiosensitizing ligands. The radiosensitization of oxygenated and hypoxic exponentially growing EMT6 cells in vitro was measured. The dose modifying factors obtained with 200 microM and 400 microM trans-bis(2-nitroimidazole)dichloroplatinum II (NIPt) in hypoxic cells were 1.5 and 2.1, respectively. For trans-bis(2-amino-5-nitrothiazole)dichloroplatinum II (Plant) under the same conditions, the dose modifying factor was 1.5 at 200 microM and 1.8 at 400 microM. Neither compound sensitized oxygenated cells when tested similar protocols. Unlike the trans complexes, (1,2-diamino-4-nitrobenzene)dichloroplatinum II (Plato) was cytotoxic toward the hypoxic cells in the absence of X rays. The time course of cytotoxicity for 100 microM Plato in exponentially growing cells showed rapid killing of hypoxic cells, and much less toxicity toward oxygenated cells. In radiosensitization studies, dose modifying factors of 1.6 and 2.0 were found with 200 microM and 400 microM Plato in hypoxic cells. The compound did not sensitize aerobic cells. The well-known platinum complex cis-dipyridinedichloroplatinum II (PyPt) represents a cis-platinum heterocyclic aromatic complex that does not have a nitro-functionality. The dose modifying factor obtained with 400 microM PyPt in hypoxic cells was 1.7. On a molar basis, the nitro-functional platinum complexes appear to be more effective as hypoxic cell radiosensitizers than the corresponding free ligands. PMID:4039304

  2. Investigation of Radiosensitivity Gene Signatures in Cancer Cell Lines

    PubMed Central

    Hall, John S.; Iype, Rohan; Senra, Joana; Taylor, Janet; Armenoult, Lucile; Oguejiofor, Kenneth; Li, Yaoyong; Stratford, Ian; Stern, Peter L.; O’Connor, Mark J.; Miller, Crispin J.; West, Catharine M. L.

    2014-01-01

    Intrinsic radiosensitivity is an important factor underlying radiotherapy response, but there is no method for its routine assessment in human tumours. Gene signatures are currently being derived and some were previously generated by expression profiling the NCI-60 cell line panel. It was hypothesised that focusing on more homogeneous tumour types would be a better approach. Two cell line cohorts were used derived from cervix [n = 16] and head and neck [n = 11] cancers. Radiosensitivity was measured as surviving fraction following irradiation with 2 Gy (SF2) by clonogenic assay. Differential gene expression between radiosensitive and radioresistant cell lines (SF2 median) was investigated using Affymetrix GeneChip Exon 1.0ST (cervix) or U133A Plus2 (head and neck) arrays. There were differences within cell line cohorts relating to tissue of origin reflected by expression of the stratified epithelial marker p63. Of 138 genes identified as being associated with SF2, only 2 (1.4%) were congruent between the cervix and head and neck carcinoma cell lines (MGST1 and TFPI), and these did not partition the published NCI-60 cell lines based on SF2. There was variable success in applying three published radiosensitivity signatures to our cohorts. One gene signature, originally trained on the NCI-60 cell lines, did partially separate sensitive and resistant cell lines in all three cell line datasets. The findings do not confirm our hypothesis but suggest that a common transcriptional signature can reflect the radiosensitivity of tumours of heterogeneous origins. PMID:24466029

  3. TGF{beta}1 polymorphisms and late clinical radiosensitivity in patients treated for gynecologic tumors

    SciTech Connect

    Ruyck, Kim de . E-mail: kim.deruyck@UGent.be; Van Eijkeren, Marc; Claes, Kathleen; Bacher, Klaus; Vral, Anne; Neve, Wilfried de; Thierens, Hubert

    2006-07-15

    Purpose: To investigate the association between six transforming growth factor {beta}1 gene (TGF{beta}1) polymorphisms (-1.552delAGG, -800G>A, -509C>T, Leu10Pro, Arg25Pro, Thr263Ile) and the occurrence of late normal tissue reactions after gynecologic radiotherapy (RT). Methods and Materials: Seventy-eight women with cervical or endometrial cancer and 140 control individuals were included in the study. According to the Common Terminology Criteria for Adverse Events version 3.0 (CTCAEv3.0) scale, 25 patients showed late adverse RT reactions (CTC2+), of whom 11 had severe complications (CTC3+). Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), single base extension and genotyping assays were performed to examine the polymorphic sites in TGF{beta}1. Results: Homozygous variant -1.552delAGG, -509TT, and 10Pro genotypes were associated with the risk of developing late severe RT reactions. Triple (variant) homozygous patients had a 3.6 times increased risk to develop severe RT reactions (p = 0.26). Neither the -800A allele, nor the 25Pro allele or the 263Ile allele were associated with clinical radiosensitivity. There was perfect linkage disequilibrium (LD) between the -1.552delAGG and the -509C>T polymorphisms, and tight LD between the -1.552/-509 and the Leu10Pro polymorphisms. Haplotype analysis revealed two major haplotypes but could not distinguish radiosensitive from nonradiosensitive patients. Conclusions: The present study shows that homozygous variant TGF{beta}1 -1.552delAGG, -509TT, and 10Pro genotypes may be associated with severe clinical radiosensitivity after gynecologic RT.

  4. [Evodiamine enhances the radiosensitivity of esophageal squamous cell cancer Eca-109 cells].

    PubMed

    Feng, Hui; Guo, Baorui; Kong, Xiangmei; Wu, Biao

    2016-07-01

    Objective To investigate the effect of evodiamine on the radiosensitivity of esophageal squamous cell cancer Eca-109 cells. Methods Eca-109 cells were treated with various concentrations of evodiamine [(10, 20, 40, 60, 80, 100, 120) μg/mL], and then cell proliferation was examined by MTT assay. After the optimal evodiamine concentration was determined, the cells were divided into radiation group (0, 2, 4, 6, 8 Gy X-ray radiation) and radiation combined with evodiamine group (80 μg/mL evodiamine and 0, 2, 4, 6, 8 Gy X-ray radiation) .The radiosensitivity of Eca-109 cells was detected using colony formation assay. Flow cytometry was used to determine cell cycle of Eca-109 cells. The protein expressions of Ku70, Ku80, DNA-PKcs and Rad51 were examined by Western blotting. Results MTT assay showed that evodiamine decreased the proliferation of Eca-109 cells in a concentration-dependent manner. The inhibition reached the maximal level at 80 μg/mL. Compared with radiotherapy alone, the combination of 80 μg/mL evodiamine and radiotherapy improved survival curve and decreased the values of D0 and Dq. Sensitizer enhancement ratio was 1.86±0.06. Furthermore, cell cycle analysis revealed that evodiamine suppressed radiotherapy-induced the G2/M arrest. Additionally, evodiamine treatment also significantly inhibited radiotherapy-induced increase in Ku70, Ku80, DNA-PKcs and Rad51 expressions. Conclusion Evodiamine enhances radiosensitivity of Eca-109 cells during radiotherapy. The effect may be associated with the inhibition of G2/M arrest and the attenuation of Ku70, Ku80, DNA-PKcs and Rad51 expressions. PMID:27363277

  5. Investigation of gold nanoparticle radiosensitization mechanisms using a free radical scavenger and protons of different energies.

    PubMed

    Jeynes, J C G; Merchant, M J; Spindler, A; Wera, A-C; Kirkby, K J

    2014-11-01

    Gold nanoparticles (GNPs) have been shown to sensitize cancer cells to x-ray radiation, particularly at kV energies where photoelectric interactions dominate and the high atomic number of gold makes a large difference to x-ray absorption. Protons have a high cross-section for gold at a large range of relevant clinical energies, and so potentially could be used with GNPs for increased therapeutic effect.Here, we investigate the contribution of secondary electron emission to cancer cell radiosensitization and investigate how this parameter is affected by proton energy and a free radical scavenger. We simulate the emission from a realistic cell phantom containing GNPs after traversal by protons and x-rays with different energies. We find that with a range of proton energies (1-250 MeV) there is a small increase in secondaries compared to a much larger increase with x-rays. Secondary electrons are known to produce toxic free radicals. Using a cancer cell line in vitro we find that a free radical scavenger has no protective effect on cells containing GNPs irradiated with 3 MeV protons, while it does protect against cells irradiated with x-rays. We conclude that GNP generated free radicals are a major cause of radiosensitization and that there is likely to be much less dose enhancement effect with clinical proton beams compared to x-rays. PMID:25296027

  6. Investigation of gold nanoparticle radiosensitization mechanisms using a free radical scavenger and protons of different energies

    NASA Astrophysics Data System (ADS)

    Jeynes, J. C. G.; Merchant, M. J.; Spindler, A.; Wera, A.-C.; Kirkby, K. J.

    2014-10-01

    Gold nanoparticles (GNPs) have been shown to sensitize cancer cells to x-ray radiation, particularly at kV energies where photoelectric interactions dominate and the high atomic number of gold makes a large difference to x-ray absorption. Protons have a high cross-section for gold at a large range of relevant clinical energies, and so potentially could be used with GNPs for increased therapeutic effect. Here, we investigate the contribution of secondary electron emission to cancer cell radiosensitization and investigate how this parameter is affected by proton energy and a free radical scavenger. We simulate the emission from a realistic cell phantom containing GNPs after traversal by protons and x-rays with different energies. We find that with a range of proton energies (1-250 MeV) there is a small increase in secondaries compared to a much larger increase with x-rays. Secondary electrons are known to produce toxic free radicals. Using a cancer cell line in vitro we find that a free radical scavenger has no protective effect on cells containing GNPs irradiated with 3 MeV protons, while it does protect against cells irradiated with x-rays. We conclude that GNP generated free radicals are a major cause of radiosensitization and that there is likely to be much less dose enhancement effect with clinical proton beams compared to x-rays.

  7. Radiosensitization of human glioma cells by tamoxifen is associated with the inhibition of PKC-ι activity in vitro

    PubMed Central

    YANG, LEI; YUAN, XIAOPENG; WANG, JIE; GU, CHENG; ZHANG, HAOWEN; YU, JIAHUA; LIU, FENJU

    2015-01-01

    The present study aimed to investigate the radiosensitizing effects of tamoxifen (TAM), a non-steroidal anti-estrogen drug, in human glioma A172 and U251 cells in vitro. A colony-forming assay revealed that TAM enhances radiosensitivity in A172 and U251 cells. Treatment with TAM also increased the percentage of apoptotic cells subsequent to ionizing radiation, and increased the expression of apoptotic markers, including cleaved caspase-3 and poly(ADP-ribose) polymerase. Ionizing radiation induced G2/M phase arrest, which was alleviated within 24 h when the radiation-induced DNA damage was repaired. However, flow cytometry analysis revealed that TAM treatment delayed the recovery of cell cycle progression. Additional examination demonstrated that TAM-mediated protein kinase C-ι (PKC-ι) inhibition may lead to the activation of pro-apoptotic B-cell lymphoma 2-associated death promoter, and the dephosphorylation of cyclin-dependent kinase 7, resulting in increased cell apoptosis and sustained G2/M phase arrest following exposure to radiation. The present data indicate that the radiosensitizing effects of TAM on glioma cells are partly due to the inhibition of PKC-ι activity in vitro. PMID:26171054

  8. REG Iα activates c-Jun through MAPK pathways to enhance the radiosensitivity of squamous esophageal cancer cells.

    PubMed

    Wakita, Akiyuki; Motoyama, Satoru; Sato, Yusuke; Koyota, Souichi; Usami, Shuetsu; Yoshino, Kei; Sasaki, Tomohiko; Imai, Kazuhiro; Saito, Hajime; Minamiya, Yoshihiro

    2015-07-01

    Identification of the key molecules that mediate susceptibility to anticancer treatments would be highly desirable. Based on clinical and cell biological studies, we recently proposed that regenerating gene (REG) Iα may be such a molecule. In the present study, we hypothesized that REG Iα increases radiosensitivity through activation of mitogen-activated protein kinase (MAPK) pathways. To test that idea, we transfected TE-5 and TE-9 squamous esophageal cancer cells with REG Iα and examined its involvement in MAPK signaling and its effect on susceptibility to radiotherapy. We found that REG Iα-expressing cells showed increased expression of c-Jun messenger RNA (mRNA) and phospho-c-Jun protein mediated via the c-Jun N-terminal kinase (JNK) pathway and extracellular signal-regulated kinase (ERK) pathway, as well as increased radiosensitivity. Immunohistochemical analysis confirmed the activation of c-Jun in tumors expressing REG Iα. Collectively, these findings suggest that REG Iα activates c-Jun via the JNK and ERK pathway, thereby enhancing radiosensitivity. PMID:25656613

  9. Isoalantolactone Enhances the Radiosensitivity of UMSCC-10A Cells via Specific Inhibition of Erk1/2 Phosphorylation

    PubMed Central

    Hu, Jiehua; Wang, Hongyan; Li, Lihua; Liu, Hua

    2015-01-01

    Background Although radiotherapy is one of the mainstream approaches for the treatment of head and neck squamous cell carcinoma (HNSCC), this cancer is always associated with resistance to radiation. In this study, the mechanism of action of isoalantolactone as well as its radiosensitizing effect was investigated in UMSCC-10A cells. Methods The radiosensitization of UMSCC-10A cells treated with isoalantolactone was analyzed by colony formation assay. The radiosensitization effects of isoalantolactone on cell proliferation, cell cycle and apoptosis regulation were examined by BrdU incorporation assay, DNA content assay and flow cytometry, respectively. Western blotting was performed to determine the effects of isoalantolactone combined with radiation on the protein expression of Mek, extracellular signal-regulated kinase (Erk1/2) as well as phosphorylated Mek and Erk1/2. Erk1/2 knockdown by siRNA was used to confirm that isoalantolactone specifically inhibited the activation of Erk1/2 signaling pathway in UMSCC-10A cells. Results Isoalantolactone enhanced the radiosensitivity of UMSCC-10A cells; the sensitivity enhanced ratios (SERs) were 1.44 and 1.63, respectively, for 2.5 and 5 μM. Moreover, isoalantolactone enhanced radiation-induced cell proliferation and apoptosis and cell cycle arrested at G2/M phase. Furthermore, no marked changes were observed in the expression of total Erk1/2 and Mek protein after radiation treatment. However, isoalantolactone was significantly reduced radiation-induced the phosphorylation of Erk1/2, whereas it altered the phosphorylation of Mek to a lesser extent. In addition, the radiosensitivity of UMSCC-10A cells with Erk1/2 knockdown was increased. Isoalantolactone cannot further prevent the proliferation of UMSCC-10A cells with Erk1/2 knockdown which other mechanism regulated cell proliferation. Conclusion Our results suggested that isoalantolactone enhanced radiation-induced apoptosis, cell cycle arrested and reduced the cell

  10. Mitochondrial stress controls the radiosensitivity of the oxygen effect: Implications for radiotherapy

    PubMed Central

    Richardson, Richard B.; Harper, Mary-Ellen

    2016-01-01

    It has been more than 60 years since the discovery of the oxygen effect that empirically demonstrates the direct association between cell radiosensitivity and oxygen tension, important parameters in radiotherapy. Yet the mechanisms underlying this principal tenet of radiobiology are poorly understood. Better understanding of the oxygen effect may explain difficulty in eliminating hypoxic tumor cells, a major cause of regrowth after therapy. Our analysis utilizes the Howard-Flanders and Alper formula, which describes the relationship of radiosensitivity with oxygen tension. Here, we assign and qualitatively assess the relative contributions of two important mechanisms. The first mechanism involves the emission of reactive oxygen species from the mitochondrial electron transport chain, which increases with oxygen tension. The second mechanism is related to an energy and repair deficit, which increases with hypoxia. Following a radiation exposure, the uncoupling of the oxidative phosphorylation system (proton leak) in mitochondria lowers the emission of reactive oxygen species which has implications for fractionated radiotherapy, particularly of hypoxic tumors. Our analysis shows that, in oxygenated tumor and normal cells, mitochondria, rather than the nucleus, are the primary loci of radiotherapy effects, especially for low linear energy transfer radiation. Therefore, the oxygen effect can be explained by radiation-induced effects in mitochondria that generate reactive oxygen species, which in turn indirectly target nuclear DNA. PMID:26894978

  11. MG132 enhances the radiosensitivity of lung cancer cells in vitro and in vivo.

    PubMed

    Zhu, Wei; Liu, Jing; Nie, Jihua; Sheng, Wenjiong; Cao, Han; Shen, Wenhao; Dong, Aijing; Zhou, Jundong; Jiao, Yang; Zhang, Shuyu; Cao, Jianping

    2015-10-01

    Radiotherapy is a common treatment modality for lung cancer, however, radioresistance remains a fundamental barrier to attaining the maximal efficacy. Cancer cells take advantage of the ubiquitin-proteasome system (UPS) for increased proliferation and decreased apoptotic cell death. MG132 (carbobenzoxyl-leucinyl-leucinyl-leucinal‑H), a specific and selective reversible inhibitor of the 26S proteasome, has shown anticancer effect in multiple types of cancers. Previously, we have reported that MG132 enhances the anti‑growth and anti-metastatic effects of irradiation in lung cancer cells. However, whether MG132 can enhance the radiosensitivity in lung cancer cells in vitro and in vivo is still unknown. In this study, we found that MG132 increased apoptosis and dicentric chromosome ratio of A549 and H1299 cells treated by irradiation. Radiation-induced NF-κB expression and IκBα phosphorylation was attenuated in MG132 plus irradiation-treated cells. The in vivo model of H1299 xenografts of nude mice showed that the tumor size of MG132 plus irradiation treated xenografts was smaller than that of irradiation, MG132 or the control group. Moreover, MG132 plus irradiation group showed significant reduced Ki67 expression. Taken together, these results demonstrate that MG132 enhances the radiosensitivity through multiple mechanisms in vitro and in vivo. PMID:26238156

  12. Activating PTEN by COX-2 inhibitors antagonizes radiation-induced AKT activation contributing to radiosensitization.

    PubMed

    Meng, Zhen; Gan, Ye-Hua

    2015-05-01

    Radiotherapy is still one of the most effective nonsurgical treatments for many tumors. However, radioresistance remains a major impediment to radiotherapy. Although COX-2 inhibitors can induce radiosensitization, the underlying mechanism is not fully understood. In this study, we showed that COX-2 selective inhibitor celecoxib enhanced the radiation-induced inhibition of cell proliferation and apoptosis in HeLa and SACC-83 cells. Treatment with celecoxib alone dephosphorylated phosphatase and tensin homolog deleted on chromosome ten (PTEN), promoted PTEN membrane translocation or activation, and correspondingly dephosphorylated or inactivated protein kinase B (AKT). By contrast, treatment with radiation alone increased PTEN phosphorylation, inhibited PTEN membrane translocation and correspondingly activated AKT in the two cell lines. However, treatment with celecoxib or another COX-2 selective inhibitor (valdecoxib) completely blocked radiation-induced increase of PTEN phosphorylation, rescued radiation-induced decrease in PTEN membrane translocation, and correspondingly inactivated AKT. Moreover, celecoxib could also upregulate PTEN protein expression by downregulating Sp1 expression, thereby leading to the activation of PTEN transcription. Our results suggested that COX-2 inhibitors could enhance radiosensitization at least partially by activating PTEN to antagonize radiation-induced AKT activation. PMID:25770423

  13. miR-494-3p Induces Cellular Senescence and Enhances Radiosensitivity in Human Oral Squamous Carcinoma Cells.

    PubMed

    Weng, Jui-Hung; Yu, Cheng-Chia; Lee, Yueh-Chun; Lin, Cheng-Wei; Chang, Wen-Wei; Kuo, Yu-Liang

    2016-01-01

    Oral squamous cell carcinoma (OSCC) is the most common malignancy of head and neck. Although radiotherapy is used for OSCC treatment, the occurrence of radioresistant cancer cells limits its efficiency. MicroRNAs (miRNAs) are non-coding RNAs with lengths of 18-25 base pairs and known to be involved in carcinogenesis. We previously demonstrated that by targeting B lymphoma Mo-MLV insertion region 1 homolog (Bmi1), miR-494-3p functions as a putative tumor suppressor miRNA in OSCC. In this study, we further discovered that miR-494-3p could enhance the radiosensitivity of SAS OSCC cells and induce cellular senescence. The overexpression of miR-494-3p in SAS cells increased the population of senescence-associated β-galactosidase positive cells, the expression of p16(INK4a) and retinoblastoma 1 (RB1), as well as downregulated Bmi1. The knockdown of Bmi1 by lentiviral-mediated delivery of specific short hairpin RNAs (shRNAs) also enhanced the radiosensitivity of SAS cells and the activation of the senescence pathway. Furthermore, the inverse correlation between Bmi1 and miR-494-3p expression was observed among OSCC tissues. Results suggest that miR-494-3p could increase the radiosensitivity of OSCC cells through the induction of cellular senescence caused by the downregulation of Bmi1. PMID:27399693

  14. miR-494-3p Induces Cellular Senescence and Enhances Radiosensitivity in Human Oral Squamous Carcinoma Cells

    PubMed Central

    Weng, Jui-Hung; Yu, Cheng-Chia; Lee, Yueh-Chun; Lin, Cheng-Wei; Chang, Wen-Wei; Kuo, Yu-Liang

    2016-01-01

    Oral squamous cell carcinoma (OSCC) is the most common malignancy of head and neck. Although radiotherapy is used for OSCC treatment, the occurrence of radioresistant cancer cells limits its efficiency. MicroRNAs (miRNAs) are non-coding RNAs with lengths of 18–25 base pairs and known to be involved in carcinogenesis. We previously demonstrated that by targeting B lymphoma Mo-MLV insertion region 1 homolog (Bmi1), miR-494-3p functions as a putative tumor suppressor miRNA in OSCC. In this study, we further discovered that miR-494-3p could enhance the radiosensitivity of SAS OSCC cells and induce cellular senescence. The overexpression of miR-494-3p in SAS cells increased the population of senescence-associated β-galactosidase positive cells, the expression of p16INK4a and retinoblastoma 1 (RB1), as well as downregulated Bmi1. The knockdown of Bmi1 by lentiviral-mediated delivery of specific short hairpin RNAs (shRNAs) also enhanced the radiosensitivity of SAS cells and the activation of the senescence pathway. Furthermore, the inverse correlation between Bmi1 and miR-494-3p expression was observed among OSCC tissues. Results suggest that miR-494-3p could increase the radiosensitivity of OSCC cells through the induction of cellular senescence caused by the downregulation of Bmi1. PMID:27399693

  15. Enhancing radiosensitivity of TE1, TE8, and TE 11 esophageal squamous carcinoma cell lines by Hdm2-siRNA targeted gene therapy in vitro

    PubMed Central

    Pirayesh Islamian, Jalil; Mohammadi, Mohsen; Baradaran, Behzad; Farajollahi, Alireza; Aghamiri, Seyed Mahmoud Reza; Asghari Jafarabadi, Mohammad; Karami, Hadi; Monfaredan, Amir; Shanehbandi, Dariush

    2016-01-01

    Introduction: Human double minute2 (hdm2) level increases in most human malignancies. Therefore, inhibition of tumor growth and also induction of radiosensitivity may be provided by hdm2 inhibitors. The effects of hdm2-siRNA on hdm2 protein expression, cell apoptosis rate, and radiosensitivity of human esophageal squamous cell carcinoma (ESCC) were studied. Methods: The hdm2 gene was silenced in TE1, TE8, and TE11 ESCC cell lines using 200nM siRNA by liposomal transfection method followed by irradiation with 0.5, 1, 2, 4, and 6 Gy γ-rays in vitro. The gene expression levels were evaluated by real time PCR and Western Blotting methods. MTT, TUNEL, and also colony forming assays were used to compare the radiosensitivity of the cell lines before and after the treatments. Results: Hdm2-siRNA reduced the hdm2 protein as compared to the vehicle control and scrambled groups, and also increased the radiation-induced apoptosis especially in TE11 cells. The related dose reduction factors (DRFs) for the silenced TE1, TE8, and TE11 cells calculated to be 1.20, 1.30, and 2.75, respectively. Conclusion: Increasing radiosensitivity of tumor cells may be provided by silencing the oncogenes. PMID:27525226

  16. Targeting FAK Radiosensitizes 3-Dimensional Grown Human HNSCC Cells Through Reduced Akt1 and MEK1/2 Signaling

    SciTech Connect

    Hehlgans, Stephanie; Department of Radiotherapy and Oncology, University of Frankfurt, Frankfurt am Main; Institute of Radiopharmacy, Helmholtz Center Dresden-Rossendorf, Dresden ; Eke, Iris; Cordes, Nils; Institute of Radiopharmacy, Helmholtz Center Dresden-Rossendorf, Dresden; Department of Radiation Oncology, University Hospital and Medical Faculty Carl Gustav Carus, Dresden University of Technology, Dresden

    2012-08-01

    Purpose: Focal adhesion kinase (FAK), a main regulator of integrin signaling and cell migration, is frequently overexpressed and hyperphosphorylated in human head-and-neck squamous cell carcinoma (HNSCC). We have previously shown that pharmacologic FAK inhibition leads to radiosensitization of 3-dimensionally grown HNSCC cell lines. To further evaluate the role of FAK in radioresistance and as a potential cancer target, we examined FAK and FAK downstream signaling in HNSCC cell lines grown in more physiologic extracellular matrix-based 3-dimensional cell cultures. Methods and Materials: Seven HNSCC cell lines were grown in 3-dimensional extracellular matrix and the clonogenic radiation survival, expression, and phosphorylation of FAK, paxillin, Akt1, extracellular signal-regulated kinase (ERK)1/2, and MEK1/2 were analyzed after siRNA-mediated knockdown of FAK, Akt1, MEK1, FAK+Akt1, or FAK+MEK1 compared with controls or stable overexpression of FAK. The role of MEK1/2 for clonogenic survival and signaling was investigated using the MEK inhibitor U0126 with or without irradiation. Results: FAK knockdown moderately or significantly enhanced the cellular radiosensitivity of 3-dimensionally grown HNSCC cells. The FAK downstream targets paxillin, Akt1, and ERK1/2 were substantially dephosphorylated under FAK depletion. FAK overexpression, in contrast, increased radiation survival and paxillin, Akt1, and ERK1/2 phosphorylation. The degree of radiosensitization upon Akt1, ERK1/2, or MEK1 depletion or U0126 was superimposable to FAK knockdown. Combination knockdown conditions (ie, Akt1/FAK, MEK1/FAK, or U0126/FAK) failed to provide additional radiosensitization. Conclusions: Our data provide further evidence for FAK as important determinant of radiation survival, which acts in the same signaling axis as Akt1 and ERK1/2. These data strongly support our hypothesis that FAK is a relevant molecular target for HNSCC radiotherapy.

  17. On the Role of low-energy electrons in the radiosensitization of DNA by gold nanoparticles

    PubMed Central

    Xiao, Fangxing; Zheng, Yi; Cloutier, Pierre; He, Yunhui; Hunting, Darel; Sanche, Léon

    2013-01-01

    Four different gold nanoparticle (GNP) preparations, including nude GNP and GNP coated either with thiolated undecane (S-C11H23), or with dithiolated diethylenetriaminepentaacetic (DTDTPA) or gadolinium (Gd) DTDTPA chelating agents were synthesized. The average diameters, for each type of nanoparticle are 5 nm, 10 and 13 nm, respectively. Dry films of plasmid DNA pGEM-3Zf(-), DNA with bound GNP and DNA with coated GNP were bombarded with 60 keV electrons. The yields of single and double strand breaks were measured as a function of exposure by electrophoresis. The binding of only one GNP without coating to DNA containing 3197 base pairs increases single and double strand breaks by a factor of 2.3 while for GNP coated with S-C11H23 this factor is reduced to 1.6. GNP coated with the DTDTPA and DTDTPA:Gd in same ratio with DNA, produce essentially no increment in damage. These results could be explained by the attenuation by the coatings of the intensity of low energy photoelectrons emitted from GNP. Thus, coatings of GNP may considerably attenuate short-range low energy electrons emitted from gold, leading to a considerable decrease of radiosensitization. According to our results, the highest radiosensitization should be obtained with GNP having the shortest possible ligand, directed to the DNA of cancer cells. PMID:22024607

  18. Molecularly Targeted Agents as Radiosensitizers in Cancer Therapy—Focus on Prostate Cancer

    PubMed Central

    Alcorn, Sara; Walker, Amanda J.; Gandhi, Nishant; Narang, Amol; Wild, Aaron T.; Hales, Russell K.; Herman, Joseph M.; Song, Danny Y.; DeWeese, Theodore L.; Antonarakis, Emmanuel S.; Tran, Phuoc T.

    2013-01-01

    As our understanding of the molecular pathways driving tumorigenesis improves and more druggable targets are identified, we have witnessed a concomitant increase in the development and production of novel molecularly targeted agents. Radiotherapy is commonly used in the treatment of various malignancies with a prominent role in the care of prostate cancer patients, and efforts to improve the therapeutic ratio of radiation by technologic and pharmacologic means have led to important advances in cancer care. One promising approach is to combine molecularly targeted systemic agents with radiotherapy to improve tumor response rates and likelihood of durable control. This review first explores the limitations of preclinical studies as well as barriers to successful implementation of clinical trials with radiosensitizers. Special considerations related to and recommendations for the design of preclinical studies and clinical trials involving molecularly targeted agents combined with radiotherapy are provided. We then apply these concepts by reviewing a representative set of targeted therapies that show promise as radiosensitizers in the treatment of prostate cancer. PMID:23863691

  19. Inhibition of HAS2 induction enhances the radiosensitivity of cancer cells via persistent DNA damage

    SciTech Connect

    Shen, Yan Nan; Shin, Hyun-Jin; Joo, Hyun-Yoo; Park, Eun-Ran; Kim, Su-Hyeon; Hwang, Sang-Gu; Park, Sang Jun; Kim, Chun-Ho; Lee, Kee-Ho

    2014-01-17

    Highlights: •HAS2 may be a promising target for the radiosensitization of human cancer. •HAS2 is elevated (up to ∼10-fold) in irradiated radioresistant and -sensitive cancer cells. •HAS2 knockdown sensitizes cancer cells to radiation. •HAS2 knockdown potentiates irradiation-induced DNA damage and apoptotic death. •Thus, the irradiation-induced up-regulation of HAS2 contributes to the radioresistance of cancer cells. -- Abstract: Hyaluronan synthase 2 (HAS2), a synthetic enzyme for hyaluronan, regulates various aspects of cancer progression, including migration, invasion and angiogenesis. However, the possible association of HAS2 with the response of cancer cells to anticancer radiotherapy, has not yet been elucidated. Here, we show that HAS2 knockdown potentiates irradiation-induced DNA damage and apoptosis in cancer cells. Upon exposure to radiation, all of the tested human cancer cell lines exhibited marked (up to 10-fold) up-regulation of HAS2 within 24 h. Inhibition of HAS2 induction significantly reduced the survival of irradiated radioresistant and -sensitive cells. Interestingly, HAS2 depletion rendered the cells to sustain irradiation-induced DNA damage, thereby leading to an increase of apoptotic death. These findings indicate that HAS2 knockdown sensitizes cancer cells to radiation via persistent DNA damage, further suggesting that the irradiation-induced up-regulation of HAS2 contributes to the radioresistance of cancer cells. Thus, HAS2 could potentially be targeted for therapeutic interventions aimed at radiosensitizing cancer cells.

  20. Transcription Factor HBP1 Enhances Radiosensitivity by Inducing Apoptosis in Prostate Cancer Cell Lines

    PubMed Central

    Chen, Yicheng; Wang, Yueping; Yu, Yanlan; Xu, Liwei; Zhang, Youyun; Yu, Shicheng; Li, Gonghui; Zhang, Zhigeng

    2016-01-01

    Radiotherapy for prostate cancer has been gradually carried out in recent years; however, acquired radioresistance often occurred in some patients after radiotherapy. HBP1 (HMG-box transcription factor 1) is a transcriptional inhibitor which could inhibit the expression of dozens of oncogenes. In our previous study, we showed that the expression level of HBP1 was closely related to prostate cancer metastasis and prognosis, but the relationship between HBP1 and radioresistance for prostate cancer is largely unknown. In this study, the clinical data of patients with prostate cancer was compared, and the positive correlation was revealed between prostate cancer brachytherapy efficacy and the expression level of HBP1 gene. Through research on prostate cancer cells in vitro, we found that HBP1 expression levels were negatively correlated with oncogene expression levels. Furthermore, HBP1 overexpression could sensitize prostate cancer cells to radiation and increase apoptosis in prostate cancer cells. In addition, animal model was employed to analyze the relationship between HBP1 gene and prostate cancer radiosensitivity in vivo; the result showed that knockdown of HBP1 gene could decrease the sensitivity to radiation of xenograft. These studies identified a specific molecular mechanism underlying prostate cancer radiosensitivity, which suggested HBP1 as a novel target in prostate cancer radiotherapy. PMID:26942107

  1. MiR-124 Radiosensitizes Human Colorectal Cancer Cells by Targeting PRRX1

    PubMed Central

    Huang, Jing; Gao, Fei; Lin, Xiaoshan; He, Lian; Li, Dan; Li, Zhijun; Ding, Yi; Chen, Longhua

    2014-01-01

    One of the challenges in the treatment of colorectal cancer patients is that these tumors show resistance to radiation. MicroRNAs (miRNAs) are involved in essential biological activities, including chemoresistance and radioresistance. Several research studies have indicated that miRNA played an important role in sensitizing cellular response to ionizing radiation (IR). In this study, we found that miR-124 was significantly down-regulated both in CRC-derived cell lines and clinical CRC samples compared with adjacent non-tumor colorectal tissues, MiR-124 could sensitize human colorectal cancer cells to IR in vitro and in vivo. We identified PRRX1, a new EMT inducer and stemness regulator as a novel direct target of miR-124 by using target prediction algorithms and luciferase assay. PRRX1 knockdown could sensitize CRC cells to IR similar to the effects caused by miR-124. Overexpression of PRRX1 in stably overexpressed-miR-124 cell lines could rescue the effects of radiosensitivity enhancement brought by miR-124. Taking these observations into consideration, we illustrated that miR-124 could increase the radiosensitivity of CRC cells by blocking the expression of PRRX1, which indicated miR-124 could act as a great therapeutic target for CRC patients. PMID:24705396

  2. Radiosensitivity study and radiation effects on morphology characterization of grey oyster mushroom Pleurotus sajor-caju

    NASA Astrophysics Data System (ADS)

    Rashid, Rosnani Abdul; Daud, Fauzi; Senafi, Sahidan; Awang, Mat Rasol; Mohamad, Azhar; Mutaat, Hassan Hamdani; Maskom, Mohd Meswan

    2014-09-01

    Radiosensitive dosage and morphology characterization of irradiated grey oyster mushroom Pleurotus sajor-caju by gamma rays was investigated due to effects of irradiation. In order to establish the effect, mycelium of P. sajor-caju was irradiated by gamma rays at dose 0.1 to 8.0 kGy with dose rate 0.227 Gy sec-1. The irradiation of mycelia was carried out at the radiation facility in Malaysian Nuclear Agency. The radiosensitivity study was performed by evaluating the percentage of survival irradiated mycelia. The lethal dose of the mycelium P. sajor-caju was determined at 4.0 kGy and LD50 to be equal at 2.2 kGy. The radiation effects on morphology were evaluated based on growth rate of irradiated mycelia, mycelia types, colonization period on substrate, morphology of fruit bodies and yields. The results shown growth rate of irradiated mycelium was slightly lower than the control and decreased as the dose increased. Irradiation was found can induced the primordia formation on PDA and the BE of irradiated seed is higher than to control. The irradiation is proven to be useful for generating new varieties of mushroom with commercial value to the industry.

  3. Radiosensitivity study and radiation effects on morphology characterization of grey oyster mushroom Pleurotus sajor-caju

    SciTech Connect

    Rashid, Rosnani Abdul; Awang, Mat Rasol; Mohamad, Azhar; Mutaat, Hassan Hamdani; Maskom, Mohd Meswan; Daud, Fauzi; Senafi, Sahidan

    2014-09-03

    Radiosensitive dosage and morphology characterization of irradiated grey oyster mushroom Pleurotus sajor-caju by gamma rays was investigated due to effects of irradiation. In order to establish the effect, mycelium of P. sajor-caju was irradiated by gamma rays at dose 0.1 to 8.0 kGy with dose rate 0.227 Gy sec{sup −1}. The irradiation of mycelia was carried out at the radiation facility in Malaysian Nuclear Agency. The radiosensitivity study was performed by evaluating the percentage of survival irradiated mycelia. The lethal dose of the mycelium P. sajor-caju was determined at 4.0 kGy and LD{sub 50} to be equal at 2.2 kGy. The radiation effects on morphology were evaluated based on growth rate of irradiated mycelia, mycelia types, colonization period on substrate, morphology of fruit bodies and yields. The results shown growth rate of irradiated mycelium was slightly lower than the control and decreased as the dose increased. Irradiation was found can induced the primordia formation on PDA and the BE of irradiated seed is higher than to control. The irradiation is proven to be useful for generating new varieties of mushroom with commercial value to the industry.

  4. Lack of a correlation between micronucleus formation and radiosensitivity in established and primary cultures of human tumours.

    PubMed Central

    Villa, R.; Zaffaroni, N.; Gornati, D.; Costa, A.; Silvestrini, R.

    1994-01-01

    The radiation-induced genotoxic damage in three established cell lines and 15 primary cultures of human malignant melanoma and ovarian carcinoma showing different radiosensitivity was tested by the cytokinesis-block micronucleus assay. A dose-related increase in micronucleus frequency was observed in all the cell systems. The mean number of micronuclei per Gy of ionising radiation per binucleated cell was respectively 0.44 +/- 0.0075 and 0.43 +/- 0.04 for M14 and JR8 malignant melanoma cell lines and 0.19 +/- 0.013 for the A2780 ovarian cancer cell line. The number of micronuclei did not rank the cell lines in the same order of radiosensitivity as clonogenic cell survival, which showed a surviving fraction at 2 Gy of 0.38 +/- 0.02 for JR8, 0.34 +/- 0.05 for M14 and 0.22 +/- 0.007 for A2780. As regards primary tumour cultures, no correlation was observed between micronucleus induction and surviving fraction at 2 Gy. In conclusion, the discrepancy we observed between micronucleus formation and cell death raises doubts about the potential of the micronucleus assay as a preclinical means to predict radiosensitivity. Images Figure 1 PMID:7981062

  5. Effect of restoration of retinoblastoma gene function on the radiosensitivity of cells of human tumor cell lines

    SciTech Connect

    Tsang, N.M.; Little, J.B.

    1994-11-01

    To assess the role of expression of the retinoblastoma (RB) gene on the sensitivity of cells to the cytotoxic effects of ionizing radiation, we transfected a normal RB gene into cells of RB{sup +} and RB{sup {minus}} osteosarcoma cell lines and an RB{sup {minus}} prostate carcinoma line and studied the radiosensitivity of the cells before and after transfection. Four transfected clones were isolated from the two RB{sup {minus}} tumor cell lines that expressed the product of the transfected normal RB gene and contained no mutations in the pocket and C-terminal regions by sequencing. A small increase in radiosensitivity was observed in cell lines transfected with the pDOL plasmid vector alone, containing the neo gene and a long terminal repeat (LTR) promoter. However, no significant change in radiosensitivity occurred in transfected cells expressing the normal RB gene compared to controls transfected with an RB{sup {minus}} plasmid. Based on this and other information, we conclude that RB gene function is not involved in the response of these human tumor cells to the cytotoxic effects of radiation. 38 refs., 5 figs., 4 tabs.

  6. TAT-ODD-p53 enhances the radiosensitivity of hypoxic breast cancer cells by inhibiting Parkin-mediated mitophagy

    PubMed Central

    Du, Shasha; Ren, Chen; Wang, Yuxia; Yuan, Yawei

    2015-01-01

    Radiation therapy has an important role in the treatment of breast cancer. Dysfunction p53 and hypoxia are typical biological characteristics of breast cancer that constitute barriers to the efficacy of radiotherapy. Mitophagy plays a protective role in cellular homeostasis under hypoxic conditions, while mitophagy is inhibited by p53 in normal cells. We explored the effects of a p53 fusion protein, TAT-ODD-p53, on the radiosensitivity of hypoxic breast cancer cells both in vitro and in vivo, as well as investigating the related molecular mechanisms. We found that selective accumulation of TAT-ODD-p53 occurred under hypoxic conditions and significantly increased tumor cell radiosensitivity both in vitro and in vivo. Mitophagy had an important role in maintaining hypoxia-induced radioresistance. Mitophagy was inhibited by TAT-ODD-p53 and this inhibition was suppressed by over-expression of Parkin in hypoxic irradiated breast cancer cells. In addition, mitophagy was induced by deletion of p53, with this effect being weakened by Parkin knockdown at a low oxygen tension. By interacting with Parkin, p53 inhibited the translocation of Parkin to the mitochondria, disrupting the protective mitophagy process. These results suggest that TAT-ODD-p53 has a significant and preferential radiosensitizing effect on hypoxic breast cancer cells by inhibition of Parkin-mediated mitophagy. PMID:26025927

  7. Highly efficient radiosensitization of human glioblastoma and lung cancer cells by a G-quadruplex DNA binding compound.

    PubMed

    Merle, Patrick; Gueugneau, Marine; Teulade-Fichou, Marie-Paule; Müller-Barthélémy, Mélanie; Amiard, Simon; Chautard, Emmanuel; Guetta, Corinne; Dedieu, Véronique; Communal, Yves; Mergny, Jean-Louis; Gallego, Maria; White, Charles; Verrelle, Pierre; Tchirkov, Andreï

    2015-01-01

    Telomeres are nucleoprotein structures at the end of chromosomes which stabilize and protect them from nucleotidic degradation and end-to-end fusions. The G-rich telomeric single-stranded DNA overhang can adopt a four-stranded G-quadruplex DNA structure (G4). Stabilization of the G4 structure by binding of small molecule ligands enhances radiosensitivity of tumor cells, and this combined treatment represents a novel anticancer approach. We studied the effect of the platinum-derived G4-ligand, Pt-ctpy, in association with radiation on human glioblastoma (SF763 and SF767) and non-small cell lung cancer (A549 and H1299) cells in vitro and in vivo. Treatments with submicromolar concentrations of Pt-ctpy inhibited tumor proliferation in vitro with cell cycle alterations and induction of apoptosis. Non-toxic concentrations of the ligand were then combined with ionizing radiation. Pt-ctpy radiosensitized all cell lines with dose-enhancement factors between 1.32 and 1.77. The combined treatment led to increased DNA breaks. Furthermore, a significant radiosensitizing effect of Pt-ctpy in mice xenografted with glioblastoma SF763 cells was shown by delayed tumor growth and improved survival. Pt-ctpy can act in synergy with radiation for efficient killing of cancer cells at concentrations at which it has no obvious toxicity per se, opening perspectives for future therapeutic applications. PMID:26542881

  8. Highly efficient radiosensitization of human glioblastoma and lung cancer cells by a G-quadruplex DNA binding compound

    PubMed Central

    Merle, Patrick; Gueugneau, Marine; Teulade-Fichou, Marie-Paule; Müller-Barthélémy, Mélanie; Amiard, Simon; Chautard, Emmanuel; Guetta, Corinne; Dedieu, Véronique; Communal, Yves; Mergny, Jean-Louis; Gallego, Maria; White, Charles; Verrelle, Pierre; Tchirkov, Andreï

    2015-01-01

    Telomeres are nucleoprotein structures at the end of chromosomes which stabilize and protect them from nucleotidic degradation and end-to-end fusions. The G-rich telomeric single-stranded DNA overhang can adopt a four-stranded G-quadruplex DNA structure (G4). Stabilization of the G4 structure by binding of small molecule ligands enhances radiosensitivity of tumor cells, and this combined treatment represents a novel anticancer approach. We studied the effect of the platinum-derived G4-ligand, Pt-ctpy, in association with radiation on human glioblastoma (SF763 and SF767) and non-small cell lung cancer (A549 and H1299) cells in vitro and in vivo. Treatments with submicromolar concentrations of Pt-ctpy inhibited tumor proliferation in vitro with cell cycle alterations and induction of apoptosis. Non-toxic concentrations of the ligand were then combined with ionizing radiation. Pt-ctpy radiosensitized all cell lines with dose-enhancement factors between 1.32 and 1.77. The combined treatment led to increased DNA breaks. Furthermore, a significant radiosensitizing effect of Pt-ctpy in mice xenografted with glioblastoma SF763 cells was shown by delayed tumor growth and improved survival. Pt-ctpy can act in synergy with radiation for efficient killing of cancer cells at concentrations at which it has no obvious toxicity per se, opening perspectives for future therapeutic applications. PMID:26542881

  9. Radiosensitization of metformin in pancreatic cancer cells via abrogating the G2 checkpoint and inhibiting DNA damage repair.

    PubMed

    Wang, Zheng; Lai, Song-Tao; Ma, Ning-Yi; Deng, Yun; Liu, Yong; Wei, Dong-Ping; Zhao, Jian-Dong; Jiang, Guo-Liang

    2015-12-01

    Recent evidences have demonstrated the potential of metformin as a novel agent for cancer prevention and treatment. Here, we investigated its ability of radiosensitization and the underlying mechanisms in human pancreatic cancer cells. In this study, we found that metformin at 5 mM concentration enhanced the radiosensitivity of MIA PaCa-2 and PANC-1 cells, with sensitization enhancement ratios of 1.39 and 1.27, respectively. Mechanistically, metformin caused abrogation of the G2 checkpoint and increase of mitotic catastrophe, associated with suppression of Wee1 kinase and in turn CDK1 Tyr15 phosphorylation. Furthermore, metformin inhibited both expression and irradiation-induced foci formation of Rad51, a key player in homologous recombination repair, ultimately leading to persistent DNA damage, as reflected by γ-H2AX and 53BP1 signaling. Finally, metformin-mediated AMPK/mTOR/p70S6K was identified as a possible upstream pathway controlling translational regulation of Wee1 and Rad51. Our data suggest that metformin radiosensitizes pancreatic cancer cells in vitro via abrogation of the G2 checkpoint and inhibition of DNA damage repair. However, the in vivo study is needed to further confirm the findings from the in vitro study. PMID:26304716

  10. Rockets, radiosensitizers, and RRx-001: an origin story part I.

    PubMed

    Oronsky, Bryan; Scicinski, Jan; Ning, Shoucheng; Peehl, Donna; Oronsky, Arnold; Cabrales, Pedro; Bednarski, Mark; Knox, Susan

    2016-03-01

    From Adam and Eve, to Darwinism, origin stories attempt to fill in the blanks, connect the dots, and define the turning points that are fundamental to subsequent developments. The purpose of this review is to present the origin story of a one-of-a-kind anticancer agent, RRx-001, which emerged from the aerospace industry as a putative radiosensitizer; not since the dynamite-to-dilator transformation of nitroglycerin in 1878 or the post-World War II explosive-to-elixir conversion of hydralazine, an ingredient in rocket fuel, to an antihypertensive, an antidepressant and an antituberculant, has energetic chemistry been harnessed for therapeutic purposes. This is Part 1 of the radiosensitization story; Parts 2 and 3, which detail the crossover activity of RRx-001 as a chemosensitizer in multiple tumor types and disease states including malaria, hemorrhagic shock and sickle cell anemia, are the subject of future reviews. PMID:27115167

  11. Inhibition of Autophagy as a Strategy to Augment Radiosensitization by the Dual Phosphatidylinositol 3-Kinase/Mammalian Target of Rapamycin Inhibitor NVP-BEZ235S⃞

    PubMed Central

    Cerniglia, George J.; Karar, Jayashree; Tyagi, Sonia; Christofidou-Solomidou, Melpo; Rengan, Ramesh; Koumenis, Constantinos

    2012-01-01

    We investigated the effect of 2-methyl-2-{4-[3-methyl-2-oxo-8-(quinolin-3-yl)-2,3-dihydro-1H-imidazo[4,5-c]quinolin-1-yl]phenyl} propanenitrile (NVP-BEZ235) (Novartis, Basel Switzerland), a dual phosphatidylinositol 3-kinase (PI3K)/mammalian target of rapamycin (mTOR) inhibitor currently being tested in phase I clinical trials, in radiosensitization. NVP-BEZ235 radiosensitized a variety of cancer cell lines, including SQ20B head and neck carcinoma cells and U251 glioblastoma cells. NVP-BEZ235 also increased in vivo radiation response in SQ20B xenografts. Knockdown of Akt1, p110α, or mTOR resulted in radiosensitization, but not to the same degree as with NVP-BEZ235. NVP-BEZ235 interfered with DNA damage repair after radiation as measured by the CometAssay and resolution of phosphorylated H2A histone family member X foci. NVP-BEZ235 abrogated the radiation-induced phosphorylation of both DNA-dependent protein kinase catalytic subunit (DNA-PKcs) and ataxia telangiectasia mutated. Knockdown of either p110α or mTOR failed to decrease the phosphorylation of DNA-PKcs, suggesting that the effect of the drug was direct rather than mediated via p110α or mTOR. The treatment of cells with NVP-BEZ235 also promoted autophagy. To assess the importance of this process in radiosensitization, we used the autophagy inhibitors 3-methyladenine and chloroquine and found that either drug increased cell killing after NVP-BEZ235 treatment and radiation. Knocking down the essential autophagy proteins autophagy related 5 (ATG5) and beclin1 increased NVP-BEZ235-mediated radiosensitization. Furthermore, NVP-BEZ235 radiosensitized autophagy-deficient ATG5(−/−) fibroblasts to a greater extent than ATG5(+/+) cells. We conclude that NVP-BEZ235 radiosensitizes cells and induces autophagy by apparently distinct mechanisms. Inhibiting autophagy via pharmacologic or genetic means increases radiation killing after NVP-BEZ235 treatment; hence, autophagy seems to be cytoprotective in this

  12. Intrinsic Radiosensitivity and Cellular Characterization of 27 Canine Cancer Cell Lines

    PubMed Central

    Maeda, Junko; Froning, Coral E.; Brents, Colleen A.; Rose, Barbara J.; Thamm, Douglas H.; Kato, Takamitsu A.

    2016-01-01

    Canine cancer cell lines have progressively been developed, but are still underused resources for radiation biology research. Measurement of the cellular intrinsic radiosensitivity is important because understanding the difference may provide a framework for further elucidating profiles for prediction of radiation therapy response. Our studies have focused on characterizing diverse canine cancer cell lines in vitro and understanding parameters that might contribute to intrinsic radiosensitivity. First, intrinsic radiosensitivity of 27 canine cancer cell lines derived from ten tumor types was determined using a clonogenic assay. The 27 cell lines had varying radiosensitivities regardless tumor type (survival fraction at 2 Gy, SF2 = 0.19–0.93). In order to understand parameters that might contribute to intrinsic radiosensitivity, we evaluated the relationships of cellular radiosensitivity with basic cellular characteristics of the cell lines. There was no significant correlation of SF2 with S-phase fraction, doubling time, chromosome number, ploidy, or number of metacentric chromosomes, while there was a statistically significant correlation between SF2 and plating efficiency. Next, we selected the five most radiosensitive cell lines as the radiosensitive group and the five most radioresistant cell lines as the radioresistant group. Then, we evaluated known parameters for cell killing by ionizing radiation, including radiation-induced DNA double strand break (DSB) repair and apoptosis, in the radiosensitive group as compared to the radioresistant group. High levels of residual γ-H2AX foci at the sites of DSBs were present in the four out of the five radiosensitive canine cancer cell lines. Our studies suggested that substantial differences in intrinsic radiosensitivity exist in canine cancer cell lines, and radiation-induced DSB repair was related to radiosensitivity, which is consistent with previous human studies. These data may assist further investigations

  13. Intrinsic Radiosensitivity and Cellular Characterization of 27 Canine Cancer Cell Lines.

    PubMed

    Maeda, Junko; Froning, Coral E; Brents, Colleen A; Rose, Barbara J; Thamm, Douglas H; Kato, Takamitsu A

    2016-01-01

    Canine cancer cell lines have progressively been developed, but are still underused resources for radiation biology research. Measurement of the cellular intrinsic radiosensitivity is important because understanding the difference may provide a framework for further elucidating profiles for prediction of radiation therapy response. Our studies have focused on characterizing diverse canine cancer cell lines in vitro and understanding parameters that might contribute to intrinsic radiosensitivity. First, intrinsic radiosensitivity of 27 canine cancer cell lines derived from ten tumor types was determined using a clonogenic assay. The 27 cell lines had varying radiosensitivities regardless tumor type (survival fraction at 2 Gy, SF2 = 0.19-0.93). In order to understand parameters that might contribute to intrinsic radiosensitivity, we evaluated the relationships of cellular radiosensitivity with basic cellular characteristics of the cell lines. There was no significant correlation of SF2 with S-phase fraction, doubling time, chromosome number, ploidy, or number of metacentric chromosomes, while there was a statistically significant correlation between SF2 and plating efficiency. Next, we selected the five most radiosensitive cell lines as the radiosensitive group and the five most radioresistant cell lines as the radioresistant group. Then, we evaluated known parameters for cell killing by ionizing radiation, including radiation-induced DNA double strand break (DSB) repair and apoptosis, in the radiosensitive group as compared to the radioresistant group. High levels of residual γ-H2AX foci at the sites of DSBs were present in the four out of the five radiosensitive canine cancer cell lines. Our studies suggested that substantial differences in intrinsic radiosensitivity exist in canine cancer cell lines, and radiation-induced DSB repair was related to radiosensitivity, which is consistent with previous human studies. These data may assist further investigations

  14. Radiosensitization of EMT6 cells by four platinum complexes

    SciTech Connect

    Teicher, B.A.; Rockwell, S.; Lee, J.B.

    1985-05-01

    The compounds described here are dichloro complexes of bivalent platinum with one or two potentially radiosensitizing ligands. The radiosensitization of oxygenated and hypoxic exponentially growing EMT6 cells in vitro was measured. The dose modifying factors obtained with 200 ..mu..M and 400 ..mu..M trans-bis(2-nitroimidazole)dichloroplatinum II (NIPt) in hypoxic cells were 1.5 and 2.1, respectively. For trans-bis(2-amino-5-nitrothiazole)dichloroplatinum II (Plant) under the same conditions, the dose modifying factor was 1.5 at 200 ..mu..M and 1.8 at 400 ..mu..M. Neither compound sensitized oxygenated cells when tested similar protocols. Unlike the trans complexes (1,2-diamino-4-nitrobenzene)dichloroplatinum II (Plato) was cytotoxic toward the hypoxic cells in the absence of X rays. The time course of cytotoxicity for 100 ..mu..M Plato in exponentially growing cells showed rapid killing of hypoxic cells, and much less toxicity toward oxygenated cells. In radiosensitization studies, dose modifying factors of 1.6 and 2.0 were found with 200 ..mu..M and 400 ..mu..M Plato in hypoxic cells. The compound did not sensitize aerobic cells. The well-known platinum complex cis-dipyridinedichloroplatinum II (PyPt) represents a cis-platinum heterocyclic aromatic complex that does not have a nitro-functionality. The dose modifying factor obtained with 400 ..mu..M PyPt in hypoxic cells was 1.7. On a molar basis, the nitro-functional platinum complexes appear to be more effective as hypoxic cell radiosensitizers than the corresponding free ligands.

  15. Examination of Gossypol-Pluronic Micelles as Potential Radiosensitizers.

    PubMed

    Tomoda, Keishiro; Chiang, Carol; Kozak, Kevin R; Kwon, Glen S

    2015-11-01

    Chemoradiotherapy, the combination of chemotherapy and radiotherapy to treat cancer, has the potential to enhance local therapeutic effects and simultaneously treat systemic disease. However, chemoradiotherapy may also enhance normal tissue effects leading to both acute and late toxicities. Furthermore, subtherapeutic chemoradiotherapy may result in aggressive tumor repopulation. Tumor-specific radiosensitizing chemotherapy may yield a synergistic therapeutic effect and avoid augmentation of normal tissue toxicity. In this study, the radiosensitizing effects of gossypol were investigated. Also, Pluronics were studied for gossypol solubilization and co-radiosensitization effects. Gossypol inhibits Bcl-2 and Bcl-XL, antiapoptotic proteins that are overexpressed in various cancer cells. Pluronic micelles (P85, F88, L35, and P123) effectively encapsulated gossypol, raising its water solubility by more than 1000-fold. Cytotoxic, anticlonogenic, and radiosensitizing effects were evaluated to characterize gossypol and Pluronic combinations. Gossypol and P85 had the strongest antiproliferative effect on A549 human lung adenocarcinoma cells in a cell viability assay. The IC50 value was seven times lower than gossypol only treatment (330 ± 70 nM vs 2400 ± 400 nM, (mean ± SE)). Gossypol and P85 showed significant inhibition of clonogenic survival, approximately 30% inhibition, compared to treatment with gossypol alone. An experimental sequencing study demonstrated greater inhibition of clonogenic survival when drug treatment followed radiation compared to a sequence of drug treatment followed by radiation. These results suggest that Pluronic micelles readily solubilize gossypol and that the combination of gossypol and P85 may augment the therapeutic effects of ionizing radiation. PMID:26246329

  16. The HSP90 Inhibitor Ganetespib Radiosensitizes Human Lung Adenocarcinoma Cells

    PubMed Central

    Gomez-Casal, Roberto; Bhattacharya, Chitralekha; Epperly, Michael W.; Basse, Per H.; Wang, Hong; Wang, Xinhui; Proia, David A.; Greenberger, Joel S.; Socinski, Mark A.; Levina, Vera

    2015-01-01

    The molecular chaperone HSP90 is involved in stabilization and function of multiple client proteins, many of which represent important oncogenic drivers in NSCLC. Utilization of HSP90 inhibitors as radiosensitizing agents is a promising approach. The antitumor activity of ganetespib, HSP90 inhibitor, was evaluated in human lung adenocarcinoma (AC) cells for its ability to potentiate the effects of IR treatment in both in vitro and in vivo. The cytotoxic effects of ganetespib included; G2/M cell cycle arrest, inhibition of DNA repair, apoptosis induction, and promotion of senescence. All of these antitumor effects were both concentration- and time-dependent. Both pretreatment and post-radiation treatment with ganetespib at low nanomolar concentrations induced radiosensitization in lung AC cells in vitro. Ganetespib may impart radiosensitization through multiple mechanisms: such as down regulation of the PI3K/Akt pathway; diminished DNA repair capacity and promotion of cellular senescence. In vivo, ganetespib reduced growth of T2821 tumor xenografts in mice and sensitized tumors to IR. Tumor irradiation led to dramatic upregulation of β-catenin expression in tumor tissues, an effect that was mitigated in T2821 xenografts when ganetespib was combined with IR treatments. These data highlight the promise of combining ganetespib with IR therapies in the treatment of AC lung tumors. PMID:26010604

  17. The HSP90 Inhibitor Ganetespib Radiosensitizes Human Lung Adenocarcinoma Cells.

    PubMed

    Gomez-Casal, Roberto; Bhattacharya, Chitralekha; Epperly, Michael W; Basse, Per H; Wang, Hong; Wang, Xinhui; Proia, David A; Greenberger, Joel S; Socinski, Mark A; Levina, Vera

    2015-01-01

    The molecular chaperone HSP90 is involved in stabilization and function of multiple client proteins, many of which represent important oncogenic drivers in NSCLC. Utilization of HSP90 inhibitors as radiosensitizing agents is a promising approach. The antitumor activity of ganetespib, HSP90 inhibitor, was evaluated in human lung adenocarcinoma (AC) cells for its ability to potentiate the effects of IR treatment in both in vitro and in vivo. The cytotoxic effects of ganetespib included; G2/M cell cycle arrest, inhibition of DNA repair, apoptosis induction, and promotion of senescence. All of these antitumor effects were both concentration- and time-dependent. Both pretreatment and post-radiation treatment with ganetespib at low nanomolar concentrations induced radiosensitization in lung AC cells in vitro. Ganetespib may impart radiosensitization through multiple mechanisms: such as down regulation of the PI3K/Akt pathway; diminished DNA repair capacity and promotion of cellular senescence. In vivo, ganetespib reduced growth of T2821 tumor xenografts in mice and sensitized tumors to IR. Tumor irradiation led to dramatic upregulation of β-catenin expression in tumor tissues, an effect that was mitigated in T2821 xenografts when ganetespib was combined with IR treatments. These data highlight the promise of combining ganetespib with IR therapies in the treatment of AC lung tumors. PMID:26010604

  18. Is Radiosensitivity Associated to Different Types of Blood Groups? (A cytogenetic study)

    PubMed Central

    Elahimanesh, Farideh; Shabestani Monfared, Ali; Khosravifarsani, Meysam; Akhavan Niaki, Haleh; Abedian, Zeinab; Hajian-Tilaki, Karimollah; Borzouisileh, Sajad; Seyfizadeh, Nayer; Amiri, Mehrangiz

    2013-01-01

    Many biological factors affect radiosensitivity. In this study, radiosensitivity among the different blood groups was investigated. Peripheral blood sample of 95 healthy people were divided into two parts. One part was irradiated with 2 Gy Co-60 gamma rays and the second one was considered as control. Then all the samples were studied by cytokinesis-blocked micronucleus assay (CBMN assay). Our study showed that the radiosensitivity index of A+ and O+ groups was significantly higher and lower than other blood groups, respectively. It seems that blood type can be used as a radiosensitivity index for determining the given dose to radiotherapy, although extensive studies are necessary. PMID:24551803

  19. Regional differences in radiosensitivity across the rat cervical spinal cord

    SciTech Connect

    Bijl, Hendrik P. . E-mail: h.p.bijl@rt.azg.nl; Luijk, Peter van; Coppes, Rob P.; Schippers, Jacobus M.; Konings, Antonius W.T.; Kogel, Albert J. van der

    2005-02-01

    Purpose: To study regional differences in radiosensitivity within the rat cervical spinal cord. Methods and materials: Three types of inhomogeneous dose distributions were applied to compare the radiosensitivity of the lateral and central parts of the rat cervical spinal cord. The left lateral half of the spinal cord was irradiated with two grazing proton beams, each with a different penumbra (20-80% isodoses): lateral wide (penumbra = 1.1 mm) and lateral tight (penumbra = 0.8 mm). In the third experiment, the midline of the cord was irradiated with a narrow proton beam with a penumbra of 0.8 mm. The irradiated spinal cord length (CT-2) was 20 mm in all experiments. The animals were irradiated with variable single doses of unmodulated protons (150 MeV) with the shoot-through method, whereby the plateau of the depth-dose profile is used rather than the Bragg peak. The endpoint for estimating isoeffective dose (ED{sub 50}) values was paralysis of fore and/or hind limbs within 210 days after irradiation. Histology of the spinal cords was performed to assess the radiation-induced tissue damage. Results: High-precision proton irradiation of the lateral or the central part of the spinal cord resulted in a shift of dose-response curves to higher dose values compared with the homogeneously irradiated cervical cord to the same 20-mm length. The ED{sub 50} values were 28.9 Gy and 33.4 Gy for the lateral wide and lateral tight irradiations, respectively, and as high as 71.9 Gy for the central beam experiment, compared with 20.4 Gy for the homogeneously irradiated 20-mm length of cervical cord. Histologic analysis of the spinal cords showed that the paralysis was due to white matter necrosis. The radiosensitivity was inhomogeneously distributed across the spinal cord, with a much more radioresistant central white matter (ED{sub 50} = 71.9 Gy) compared with lateral white matter (ED{sub 50} values = 28.9 Gy and 33.4 Gy). The gray matter did not show any noticeable lesions, such

  20. The preclinical study of predicting radiosensitivity in human nasopharyngeal carcinoma xenografts by 18F-ML-10 animal- PET/CT imaging

    PubMed Central

    Wang, Siyang; Zheng, Yujia; Wang, Mingwei; Gu, Bingxin; Zhang, Jianping; Zhang, Yongping; Zhang, Yingjian

    2016-01-01

    Previous studies have reported that the radiosensitivity is associated with apoptosis. Hereby, we aimed to investigate the value of 18F-ML-10 PET/CT, which selectively targeted cells undergoing apoptosis, in predicting radiosensitivity of human nasopharyngeal carcinoma (NPC) xenografts. We used CNE1 (highly differentiated) and CNE2 (poorly differentiated) NPC cell lines to construct tumor models, which had very different radiosensitivities. After irradiation, the volumes of CNE2 tumors decreased significantly while those of CNE1 tumors increased. In 18F-ML-10 imaging, the values of tumor/muscle (T/M) between CNE1 and CNE2 mice were statistically different at both 24 h and 48 h after irradiation. Besides, ΔT/M1-0 and ΔT/M2-0 of CNE2 mice were higher than those of CNE1 mice, demonstrating obvious discrepancy. Furthermore, we observed obvious changes of radioactive distribution in CNE2 group. On the contrary, T/M of 18F-FDG in irradiation group revealed no obvious change in both CNE1 and CNE2 groups. In conclusion, 18F-ML-10 animal PET/CT showed its potential to predict radiosensitivity in NPC. PMID:26942701

  1. Down-Regulation of EBV-LMP1 Radio-Sensitizes Nasal Pharyngeal Carcinoma Cells via NF-κB Regulated ATM Expression

    PubMed Central

    Xiao, Lanbo; Tang, Min; Liu, Liyu; Li, Zijian; Deng, Mengyao; Sun, Lunquan; Cao, Ya

    2011-01-01

    Background The latent membrane protein 1 (LMP1) encoded by EBV is expressed in the majority of EBV-associated human malignancies and has been suggested to be one of the major oncogenic factors in EBV-mediated carcinogenesis. In previous studies we experimentally demonstrated that down-regulation of LMP1 expression by DNAzymes could increase radiosensitivity both in cells and in a xenograft NPC model in mice. Results In this study we explored the molecular mechanisms underlying the radiosensitization caused by the down-regulation of LMP1 in nasopharyngeal carcinoma. It was confirmed that LMP1 could up-regulate ATM expression in NPCs. Bioinformatic analysis of the ATM ptomoter region revealed three tentative binding sites for NF-κB. By using a specific inhibitor of NF-κB signaling and the dominant negative mutant of IkappaB, it was shown that the ATM expression in CNE1-LMP1 cells could be efficiently suppressed. Inhibition of LMP1 expression by the DNAzyme led to attenuation of the NF-κB DNA binding activity. We further showed that the silence of ATM expression by ATM-targeted siRNA could enhance the radiosensitivity in LMP1 positive NPC cells. Conclusions Together, our results indicate that ATM expression can be regulated by LMP1 via the NF-κB pathways through direct promoter binding, which resulted in the change of radiosensitivity in NPCs. PMID:22096476

  2. Targeted radiosensitization of ETS fusion-positive prostate cancer through PARP1 inhibition.

    PubMed

    Han, Sumin; Brenner, J Chad; Sabolch, Aaron; Jackson, Will; Speers, Corey; Wilder-Romans, Kari; Knudsen, Karen E; Lawrence, Theodore S; Chinnaiyan, Arul M; Feng, Felix Y

    2013-10-01

    ETS gene fusions, which result in overexpression of an ETS transcription factor, are considered driving mutations in approximately half of all prostate cancers. Dysregulation of ETS transcription factors is also known to exist in Ewing's sarcoma, breast cancer, and acute lymphoblastic leukemia. We previously discovered that ERG, the predominant ETS family member in prostate cancer, interacts with the DNA damage response protein poly (ADP-ribose) polymerase 1 (PARP1) in human prostate cancer specimens. Therefore, we hypothesized that the ERG-PARP1 interaction may confer radiation resistance by increasing DNA repair efficiency and that this radio-resistance could be reversed through PARP1 inhibition. Using lentiviral approaches, we established isogenic models of ERG overexpression in PC3 and DU145 prostate cancer cell lines. In both cell lines, ERG overexpression increased clonogenic survival following radiation by 1.25 (±0.07) fold (mean ± SEM) and also resulted in increased PARP1 activity. PARP1 inhibition with olaparib preferentially radiosensitized ERG-positive cells by a factor of 1.52 (±0.03) relative to ERG-negative cells (P < .05). Neutral and alkaline COMET assays and immunofluorescence microscopy assessing γ-H2AX foci showed increased short- and long-term efficiencies of DNA repair, respectively, following radiation that was preferentially reversed by PARP1 inhibition. These findings were verified in an in vivo xenograft model. Our findings demonstrate that ERG overexpression confers radiation resistance through increased efficiency of DNA repair following radiation that can be reversed through inhibition of PARP1. These results motivate the use of PARP1 inhibitors as radiosensitizers in patients with localized ETS fusion-positive cancers. PMID:24204199

  3. Enhancement of radiosensitivity in human glioblastoma cells by the DNA N-mustard alkylating agent BO-1051 through augmented and sustained DNA damage response

    PubMed Central

    2011-01-01

    Background 1-{4-[Bis(2-chloroethyl)amino]phenyl}-3-[2-methyl-5-(4-methylacridin-9-ylamino)phenyl]urea (BO-1051) is an N-mustard DNA alkylating agent reported to exhibit antitumor activity. Here we further investigate the effects of this compound on radiation responses of human gliomas, which are notorious for the high resistance to radiotherapy. Methods The clonogenic assay was used to determine the IC50 and radiosensitivity of human glioma cell lines (U87MG, U251MG and GBM-3) following BO-1051. DNA histogram and propidium iodide-Annexin V staining were used to determine the cell cycle distribution and the apoptosis, respectively. DNA damage and repair state were determined by γ-H2AX foci, and mitotic catastrophe was measure using nuclear fragmentation. Xenograft tumors were measured with a caliper, and the survival rate was determined using Kaplan-Meier method. Results BO-1051 inhibited growth of human gliomas in a dose- and time-dependent manner. Using the dosage at IC50, BO-1051 significantly enhanced radiosensitivity to different extents [The sensitizer enhancement ratio was between 1.24 and 1.50 at 10% of survival fraction]. The radiosensitive G2/M population was raised by BO-1051, whereas apoptosis and mitotic catastrophe were not affected. γ-H2AX foci was greatly increased and sustained by combined BO-1051 and γ-rays, suggested that DNA damage or repair capacity was impaired during treatment. In vivo studies further demonstrated that BO-1051 enhanced the radiotherapeutic effects on GBM-3-beared xenograft tumors, by which the sensitizer enhancement ratio was 1.97. The survival rate of treated mice was also increased accordingly. Conclusions These results indicate that BO-1051 can effectively enhance glioma cell radiosensitivity in vitro and in vivo. It suggests that BO-1051 is a potent radiosensitizer for treating human glioma cells. PMID:21244709

  4. Radiosensitizing effect of carboplatin and paclitaxel to carbon-ion beam irradiation in the non-small-cell lung cancer cell line H460.

    PubMed

    Kubo, Nobuteru; Noda, Shin-ei; Takahashi, Akihisa; Yoshida, Yukari; Oike, Takahiro; Murata, Kazutoshi; Musha, Atsushi; Suzuki, Yoshiyuki; Ohno, Tatsuya; Takahashi, Takeo; Nakano, Takashi

    2015-03-01

    The present study investigated the ability of carboplatin and paclitaxel to sensitize human non-small-cell lung cancer (NSCLC) cells to carbon-ion beam irradiation. NSCLC H460 cells treated with carboplatin or paclitaxel were irradiated with X-rays or carbon-ion beams, and radiosensitivity was evaluated by clonogenic survival assay. Cell proliferation was determined by counting the number of viable cells using Trypan blue. Apoptosis and senescence were evaluated by terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) staining and senescence-associated β-galactosidase (SA-β-gal) staining, respectively. The expression of cleaved caspase-3, Bax, p53 and p21 was analyzed by western blotting. Clonogenic survival assays demonstrated a synergistic radiosensitizing effect of carboplatin and paclitaxel with carbon-ion beams; the sensitizer enhancement ratios (SERs) at the dose giving a 10% survival fraction (D10) were 1.21 and 1.22, respectively. Similarly, carboplatin and paclitaxel showed a radiosensitizing effect with X-rays; the SERs were 1.41 and 1.29, respectively. Cell proliferation assays validated the radiosensitizing effect of carboplatin and paclitaxel with both carbon-ion beam and X-ray irradiation. Carboplatin and paclitaxel treatment combined with carbon-ion beams increased TUNEL-positive cells and the expression of cleaved caspase-3 and Bax, indicating the enhancement of apoptosis. The combined treatment also increased SA-β-gal-positive cells and the expression of p53 and p21, indicating the enhancement of senescence. In summary, carboplatin and paclitaxel radiosensitized H460 cells to carbon-ion beam irradiation by enhancing irradiation-induced apoptosis and senescence. PMID:25599995

  5. HDAC inhibition radiosensitizes human normal tissue cells and reduces DNA Double-Strand Break repair capacity.

    PubMed

    Purrucker, Jan C; Fricke, Andreas; Ong, Mei Fang; Rübe, Christian; Rübe, Claudia E; Mahlknecht, Ulrich

    2010-01-01

    HDAC inhibitors (HDACi) are gaining increasing attention in the treatment of cancer, particularly in view of their therapeutic effectiveness and assumed mild toxicity profile. While numerous studies have investigated the role of HDACi in tumor cells, little is known about their effects on normal tissue cells. We studied the effect of suberoylanilide hydroxamic acid (SAHA), MS275, sodium-butyrate and valproic acid in healthy human fibroblasts and found HDACi-treatment to go along with increased radiosensitivity and reduced DSB repair capacity. In view of the potential genotoxic effects of HDACi-treatment, particularly when being administered long-term for chronic disease or when given to children, to women of childbearing age or their partners or in combination with radiotherapy, an extensive education of patients and prescribing physicians as well as a stringent definition of clinical indications is urgently required. PMID:19956891

  6. Bromodeoxyuridine-mediated radiosensitization in hum glioma: The effect of concentration, duration, and fluoropyrimidine modulation

    SciTech Connect

    McLaughlin, P.W.; Lawrence, T.S.; Seabury, H.

    1994-10-15

    To define the relative influence of duration of exposure, concentration, and modulation by fluorodeoxyuridines (FdUrd) on the incorporation of 5-bromo-2-deoxyuridine (BrdUrd) into DNA of human malignant glioma line (D-54) in vitro and in vivo. In vitro studies: an established human malignant glioma line (D-54)was exposed to a clinically achievable concentration of BrdUrd to model intravenous (1 {mu}M BrdUrd) and intraarterial (4 {mu}MBrdUrd) conditions. The influence of modulation was assessed using 1 nM FdUrd. Incorporation of BrdUrd, radiosensitization, and cytotoxicity were determined after 24, 72, and 120 h drug exposures. In Vivo studies: nude mice bearing D-54 xenografts were infused with BrdUrd at 100 mg/kg/day for 7 and 14 days or BrdUrd at 400 mg/kg/day for 5 days. The influence of modulation was assessed by combining 100 mg/kg/day of BrdUrd with 0.1, 0.3 and 1 mg/kg/day FdUrd for 7 days. Incorporation of BrddUrd into the DNA of tumor, gut, and marrow were determined. In Vitro: thymidine replacement and radiosensitization were a function of concentration, and incorporation began to plateau after 2 to 3 population doublings. Modulation with 1 nM FdUrd significantly increased incorporation. Radiosensitization was a linear function of thymidine replacement under all conditions tested. In Vivo: infusion with 400 mg/kg/day for 5 days resulted in greater tumor incorporation (10.3 {plus_minus} 0.4% thymidine replaced) than treatment with 100 mg/kg/day for 14 days (6.0 {plus_minus} 0.6% of thymidine replaced) than treatment with 100 mg/kg/day for 14 days for 14 days (6.0 {plus_minus} 0.6% of thymidine replaced). Infusion of FdUrd with BrdUrd increased normal tissue incorporation of BrdUrd, but failed to increase BrdUrd incorporation in tumor cells. These results suggest that relatively short, high dose rate infusions may be preferable to long, low dose rate infusions. 33 refs., 5 figs., 2 tabs.

  7. Superiority of Low Energy 160 KV X-Rays Compared to High Energy 6 MV X-Rays in Heavy Element Radiosensitization for Cancer Treatment

    NASA Astrophysics Data System (ADS)

    Lim, Sara N.; Pradhan, Anil K.; Nahar, Sultana N.; Barth, Rolf F.; Yang, Weilian; Nakkula, Robin J.; Palmer, Alycia; Turro, Claudia

    2013-06-01

    High energy X-rays in the MeV range are generally employed in conventional radiation therapy from linear accelerators (LINAC) to ensure sufficient penetration depths. However, lower energy X-rays in the keV range may be more effective when coupled with heavy element (high-Z or HZ) radiosensitizers. Numerical simulations of X-ray energy deposition for tumor phantoms sensitized with HZ radiosensitizers were performed using the Monte Carlo code Geant4. The results showed enhancement in energy deposition to radiosensitized phantoms relative to unsensitized phantoms for low energy X-rays in the keV range. In contrast, minimal enhancement was seen using high energy X-rays in the MeV range. Dose enhancement factors (DEFs) were computed and showed radiosensitization only in the low energy range < 200 keV, far lower than the energy of the majority of photons in the LINAC energy range. In vitro studies were carried to demonstrate the tumoricidal effects of HZ sensitized F98 rat glioma cells following irradiation with both low energy 160 kV and high energy 6 MV X-ray sources. The platinum compound, pyridine terpyridine Pt(II) nitrate, was initially used because it was 7x less toxic that an equivalent amount of carboplatin in vitro studies. This would allow us to separate the radiotoxic and the chemotoxic effects of HZ sensitizers. Results from this study showed a 10-fold dose dependent reduction in surviving fractions (SF) of radiosensitized cells treated with low energy 160 kV X-rays compared to those treated with 6 MV X-rays. This is in agreement with our simulations that show an increase in dose deposition in radiosensitized tumors for low energy X-rays. Due to unforeen in vivo toxicity, however, another in vitro study was performed using the commonly used, Pt-based chemotherapeutic drug carboplatin which confirmed earlier results. This lays the ground work for a planned in vivo study using F98 glioma bearing rats. This study demonstrates that while high energy X-rays are

  8. AZD5438, an Inhibitor of Cdk1, 2, and 9, Enhances the Radiosensitivity of Non-Small Cell Lung Carcinoma Cells

    SciTech Connect

    Raghavan, Pavithra; Tumati, Vasu; Yu Lan; Chan, Norman; Tomimatsu, Nozomi; Burma, Sandeep; Bristow, Robert G.; Saha, Debabrata

    2012-11-15

    Purpose: Radiation therapy (RT) is one of the primary modalities for treatment of non-small cell lung cancer (NSCLC). However, due to the intrinsic radiation resistance of these tumors, many patients experience RT failure, which leads to considerable tumor progression including regional lymph node and distant metastasis. This preclinical study evaluated the efficacy of a new-generation cyclin-dependent kinase (Cdk) inhibitor, AZD5438, as a radiosensitizer in several NSCLC models that are specifically resistant to conventional fractionated RT. Methods and Materials: The combined effect of ionizing radiation and AZD5438, a highly specific inhibitor of Cdk1, 2, and 9, was determined in vitro by surviving fraction, cell cycle distribution, apoptosis, DNA double-strand break (DSB) repair, and homologous recombination (HR) assays in 3 NSCLC cell lines (A549, H1299, and H460). For in vivo studies, human xenograft animal models in athymic nude mice were used. Results: Treatment of NSCLC cells with AZD5438 significantly augmented cellular radiosensitivity (dose enhancement ratio rangeing from 1.4 to 1.75). The degree of radiosensitization by AZD5438 was greater in radioresistant cell lines (A549 and H1299). Radiosensitivity was enhanced specifically through inhibition of Cdk1, prolonged G{sub 2}-M arrest, inhibition of HR, delayed DNA DSB repair, and increased apoptosis. Combined treatment with AZD5438 and irradiation also enhanced tumor growth delay, with an enhancement factor ranging from 1.2-1.7. Conclusions: This study supports the evaluation of newer generation Cdk inhibitors, such as AZD5438, as potent radiosensitizers in NSCLC models, especially in tumors that demonstrate variable intrinsic radiation responses.

  9. Bacterial radiosensitization by using radiation processing in combination with essential oil: Mechanism of action

    NASA Astrophysics Data System (ADS)

    Lacroix, Monique; Caillet, Stéphane; Shareck, Francois

    2009-07-01

    Spice extracts under the form of essential oils were tested for their efficiency to increase the relative radiosensitivity of Listeria monocytogenes and Escherichia coli O157H7 in culture media. The two pathogens were treated by gamma-irradiation alone or in combination with oregano essential oil to evaluate their mechanism of action. The membrane murein composition, and the intracellular and extracellular concentration of ATP was determined. The bacterial strains were treated with two irradiation doses: 1.2 kGy to induce cell damage and 3.5 kGy to cause cell death for L. monocytogenes. A dose of 0.4 kGy to induce cell damages, 1.1 kGy to obtain viable but nonculturable (VBNC) state and 1.3 kGy to obtain a lethal dose was also applied on E. coli O157H7. Oregano essential oil was used at 0.020% and 0.025% (w/v), which is the minimum inhibitory concentration (MIC) for L. monocytogenes. For E. coli O157H7, a concentration of 0.006% and 0.025% (w/v) which is the minimum inhibitory concentration was applied. The use of essential oils in combination with irradiation has permitted an increase of the bacterial radiosensitization by more than 3.1 times. All treatments had also a significant effect ( p⩽0.05) on the murein composition, although some muropeptides did not seem to be affected by the treatment. Each treatment influenced differently the relative percentage and number of muropeptides. There was a significant ( p⩽0.05) correlation between the reduction of intracellular ATP and increase in extracellular ATP following treatment of the cells with oregano oil. The reduction of intracellular ATP was even more important when essential oil was combined with irradiation, but irradiation of L. monocytogenes alone induced a significant decrease ( p⩽0.05) of the internal ATP without affecting the external ATP.

  10. Possible role of chromatin alteration in the radiosensitivity of ataxia-telangiectasia.

    PubMed

    Hittelman, W N; Pandita, T K

    1994-12-01

    Cells derived from individuals with ataxia-telangiectasia (A-T) are known to exhibit increased sensitivity to ionizing radiation and certain radiomimetic chemical agents. Here we summarize our findings regarding the role of chromosome damage and repair in this radiosensitivity. Lymphoblastoid cells derived from A-T homozygotes were characterized for initial chromosome (premature chromosome condensation) and DNA (neutral filter elution) damage and repair kinetics in cells from G1 and G2 cell cycle phases. Despite initial levels of DNA damage being similar to normal controls, A-T cells exhibited nearly a two-fold higher initial amount of chromosome damage. Different A-T cell lines exhibited differing chromosome repair capacities compared with control lymphoblastoid cell lines. These results suggest that A-T cells have an altered chromatin structure whereby DNA double-strand breaks are apparently more efficiently converted into chromosome breaks. Four A-T heterozygote cell lines were examined for chromosome damage and repair in the same fashion and all exhibited increased levels of chromosome damage, although the degree of sensitivity was more prominent in G2 phase cells (two-fold higher) than in G1 phase cells (1.5-fold higher than normal controls). These results suggest that A-T heterozygotes also exhibit an altered chromatin structure which impacts on chromosome damage expression. Of interest, A-T cells also exhibited increased chromosome stickiness after irradiation, and telomere regions appeared to be frequently involved. While the molecular basis for preferential telomere involvement is not understood, these results again suggest that structural alterations in the chromatin of A-T cells may play an important role in A-T radiosensitivity. PMID:7836837

  11. Electrophilic 5-Substituted Uracils as Potential Radiosensitizers: A Density Functional Theory Study.

    PubMed

    Makurat, Samanta; Chomicz-Mańka, Lidia; Rak, Janusz

    2016-08-18

    Although 5-bromo-2'-deoxyuridine (5BrdU) possesses significant radiosensitizing power in vitro, clinical studies do not confirm any advantages of radiotherapy employing 5BrdU. This situation calls for a continuous search for efficient radiosensitizers. Using the proposed mechanism of radiosensitization by 5BrdU, we propose a series of 5-substituted uracils, XYU, that should undergo efficient dissociative electron attachment. The DFT-calculated thermodynamic and kinetic data concerning the XYU degradations induced by electron addition suggests that some of the scrutinized derivatives have much better characteristics than 5BrdU itself. Synthesis of these promising candidates for radiosensitizers, followed by studies of their radiosensitizing properties in DNA context, and ultimately in cancer cells, are further steps to confirm their potential applicability in anticancer treatment. PMID:27156191

  12. Enhancement of photosensitization efficiency by various combinations with radiosensitization in an experimental Ehrlich ascites tumor

    NASA Astrophysics Data System (ADS)

    Luksiene, Zivile; Kaspariunaite, G.; Aleknavicius, E.; Valuckas, Konstantinas P.

    1996-12-01

    According to our previous results porphyrin can interact not only with visible light but with ionizing radiation also. This phenomenon gives us new possibility to combine photosensitization with radiosensitization. Data obtained on BALB/c mice with 7-day Ehrlich ascites tumors pretreated with 30 mg/kg HP dimethylether (not toxic and not mutagenic concentration) and irradiated with 60Co source (2 Gy) and visible light source (5 J/cm2) showed remarkable inhibition of tumor growth. Two Gy alone inhibited Ehrlich ascites tumor growth by 17%, whereas combination of 30 mg/kg HPde and 2 Gy (radiosensitization) -- by 38%. Photosensitization (30 mg/kg HPde plus 5 J/cm2) showed 37% tumor growth inhibition. Combination of photosensitization with radiosensitization inhibited tumor growth by 87%. It is important to note, that sequence of treatments (radiosensitization - 1 h - photosensitization or photosensitization - 1 h - radiosensitization) had no influence on tumor growth inhibition.

  13. Gold nanoparticles functionalization notably decreases radiosensitization through hydroxyl radical production under ionizing radiation.

    PubMed

    Gilles, Manon; Brun, Emilie; Sicard-Roselli, Cécile

    2014-11-01

    The purpose of this work was to study the influence of gold nanoparticles (GNP) coating on hydroxyl radical (HO) production under ionizing radiation. Though radiosensitizing mechanisms are still unknown, radical oxygen species are likely to be involved, especially HO. We synthesized six different types of GNP, choosing relevant ligands such as polyethylene glycol or human serum albumin. A great attention was paid to characterize these GNP in terms of size, charge and number of atoms in the coating. Our results show that functionalization dramatically decreases HO production, which is correlated to reduced plasmidic DNA damages. These findings are of high importance as GNP translation from fundamental research to applied medicine requires their functionalization to increase blood circulation time and specific cancerous cells addressing. We suggest that to keep GNP efficient for radiotherapy, a wispy coating is required. PMID:25454667

  14. Gadolinium-based nanoparticles for theranostic MRI-radiosensitization.

    PubMed

    Lux, François; Sancey, Lucie; Bianchi, Andrea; Crémillieux, Yannick; Roux, Stéphane; Tillement, Olivier

    2015-01-01

    A rapid development of gadolinium-based nanoparticles is observed due to their attractive properties as MRI-positive contrast agents. Indeed, they display high relaxivity, adapted biodistribution and passive uptake in the tumor thanks to enhanced permeability and retention effect. In addition to these imaging properties, it has been recently shown that they can act as effective radiosensitizers under different types of irradiation (radiotherapy, neutron therapy or hadron therapy). These new therapeutic modalities pave the way to therapy guided by imaging and to personalized medicine. PMID:25715316

  15. Neuropathy of nitroimidazole radiosensitizers: clinical and pathological description

    SciTech Connect

    Wasserman, T.H.; Nelson, J.S.; VonGerichten, D.

    1984-09-01

    The dose limiting toxicity of the nitroimidazole radiosensitizers is peripherial neuropathy. Improved pharmacology of newer drugs has eliminated the encephalopathy. Peripheral neuropathies are predominently mild to moderate paresthesias of both hands and feet. Subjective changes occur with or without minimal objective changes on neurologic exam. All of the neuropathies occurred within 30 days of the last drug dose and are of varible duration. Sural nerve biopsies from patients indicate progressive axonal degeneration affecting both large and small caliber myelinated fibers. Axonal damage appears to be more severe in the distal portion of the nerves. More data are needed for correlation of clinical and pathological changes.

  16. Radioprotection and Cell Cycle Arrest of Intestinal Epithelial Cells by Darinaparsin, a Tumor Radiosensitizer

    SciTech Connect

    Tian, Junqiang; Doi, Hiroshi; Saar, Matthias; Santos, Jennifer; Li, Xuejun; Peehl, Donna M.; Knox, Susan J.

    2013-12-01

    Purpose: It was recently reported that the organic arsenic compound darinaparsin (DPS) is a cytotoxin and radiosensitizer of tumor cells in vitro and in subcutaneous xenograft tumors. Surprisingly, it was also found that DPS protects normal intestinal crypt epithelial cells (CECs) from clonogenic death after ionizing radiation (IR). Here we tested the DPS radiosensitizing effect in a clinically relevant model of prostate cancer and explored the radioprotective effect and mechanism of DPS on CECs. Methods and Materials: The radiation modification effect of DPS was tested in a mouse model of orthotopic xenograft prostate cancer and of IR-induced acute gastrointestinal syndrome. The effect of DPS on CEC DNA damage and DNA damage responses was determined by immunohistochemistry. Results: In the mouse model of IR-induced gastrointestinal syndrome, DPS treatment before IR accelerated recovery from body weight loss and increased animal survival. DPS decreased post-IR DNA damage and cell death, suggesting that the radioprotective effect was mediated by enhanced DNA damage repair. Shortly after DPS injection, significant cell cycle arrest was observed in CECs at both G1/S and G2/M checkpoints, which was accompanied by the activation of cell cycle inhibitors p21 and growth arrest and DNA-damage-inducible protein 45 alpha (GADD45A). Further investigation revealed that DPS activated ataxia telangiectasia mutated (ATM), an important inducer of DNA damage repair and cell cycle arrest. Conclusions: DPS selectively radioprotected normal intestinal CECs and sensitized prostate cancer cells in a clinically relevant model. This effect may be, at least in part, mediated by DNA damage response activation and has the potential to significantly increase the therapeutic index of radiation therapy.

  17. ZnFe2O4 nanoparticles as radiosensitizers in radiotherapy of human prostate cancer cells.

    PubMed

    Meidanchi, Alireza; Akhavan, Omid; Khoei, Samideh; Shokri, Ali A; Hajikarimi, Zahra; Khansari, Nakisa

    2015-01-01

    Nanoparticles of high-Z elements exhibit stronger photoelectric effects than soft tissues under gamma irradiation. Hence, they can be used as effective radiosensitizers for increasing the efficiency of current radiotherapy. In this work, superparamagnetic zinc ferrite spinel (ZnFe2O4) nanoparticles were synthesized by a hydrothermal reaction method and used as radiosensitizers in cancer therapy. The magnetic nanoparticles showed fast separation from solutions (e.g., ~1 min for 2 mg mL(-1) of the nanoparticles in ethanol) by applying an external magnetic field (~1T). The ZnFe2O4 nanoparticles were applied in an in vitro radiotherapy of lymph node carcinoma of prostate cells (as high radioresistant cells) under gamma irradiation of (60)Co source. The nanoparticles exhibited no significant effects on the cancer cells up to the high concentration of 100 μg mL(-1), in the absence of gamma irradiation. The gamma irradiation alone (2Gy dose) also showed no significant effects on the cells. However, gamma irradiation in the presence of 100 μg mL(-1) ZnFe2O4 nanoparticles resulted in ~53% inactivation of the cells (~17 times higher than the inactivation that occurred under gamma irradiation alone) after 24h. The higher cell inactivation was assigned to interaction of gamma radiation with nanoparticles (photoelectric effect), resulting in a high level electron release in the media of the radioresistant cells. Our results indicated that ZnFe2O4 nanoparticles not only can be applied in increasing the efficiency of radiotherapy, but also can be easily separated from the cell environment by using an external magnetic field after the radiotherapy. PMID:25492003

  18. Radiosensitization by 6-aminonicotinamide and 2-deoxy-D-glucose in human cancer cells.

    PubMed

    Varshney, R; Dwarakanath, Bs; Jain, V

    2005-05-01

    The aim was to exploit simultaneous inhibition of glycolytic and pentose phosphate pathways of energy production for radiosensitization using 2-deoxy-D-glucose (2-DG) and 6-aminonicotinamide (6-AN) in transformed mammalian cells. Two human tumour cell lines (cerebral glioma, BMG-1 and squamous carcinoma cells 4197) were investigated. 2-DG and/or 6-AN added at the time of irradiation were present for 4 h after radiation. Radiation-induced cell death (macrocolony assay), cytogenetic damage (micronuclei formation), cell cycle delay (bromodeoxyuridne (BrdU) pulse chase), apoptosis (externalization of phosphotidylserine (PS) by annexin V), chromatin-bound proliferation cell nuclear antigen (PCNA) and cellular glutathione (GSH) levels were investigated as parameters of radiation response. The presence of 2-DG (5 mM) during and for 4 h after irradiation increased the radiation-induced micronuclei formation and cell death, and caused a time-dependent decrease in GSH levels in BMG-1 cells while no significant effects could be observed in 4197 cells. 6-AN (5 microM) enhanced the radiosensitivity of both cell lines and reduced the GSH content by nearly 50% in gamma-irradiated 4197 cells. Combining 2-DG and 6-AN caused a profound decrease in the GSH content and enhanced the radiation damage in both the cell lines by increasing mitotic and apoptotic cell death. Further, the combination (2-DG + 6-AN) enhanced the radiation-induced G2 block, besides arresting cells in S phase and inhibited the recruitment of PCNA. The combination of 2-DG and 6-AN enhances radiation damage by modifying damage response pathways and has the potential for improving radiotherapy of cancer. PMID:16076755

  19. Prolonged survival in pancreatic cancer patients with increased regucalcin gene expression: Overexpression of regucalcin suppresses the proliferation in human pancreatic cancer MIA PaCa-2 cells in vitro.

    PubMed

    Yamaguchi, Masayoshi; Osuka, Satoru; Weitzmann, M Neale; El-Rayes, Bassel F; Shoji, Mamoru; Murata, Tomiyasu

    2016-05-01

    Approximately 90% of all pancreatic cancers are pancreatic ductal adenocarcinomas (PDAC). PDAC is a highly aggressive malignancy and is one of the deadliest. This poor clinical outcome is due to the prominent resistance of pancreatic cancer to drug and radiation therapies. Regucalcin plays a pivotal role as a suppressor protein in signal transduction in various types of cells including tumor tissues. We demonstrated that the prolonged survival is induced in PDAC patients with increased regucalcin gene expression using a dataset of PDAC obtained from GEO database (GSE17891) together with the clinical annotation data file. Moreover, overexpression of regucalcin with full length was demonstrated to suppress the proliferation, cell death and migration in human pancreatic cancer MIA PaCa-2 (K-ras mutated) cells that possess resistance to drug and radiation therapies. Suppressive effects of regucalcin on cell proliferation and death were not seen in the cells overexpressed with regucalcin cDNA alternatively spliced variants (deleted exon 4 or deleted exon 4 and 5). Regucalcin was suggested to induce G1 and G2/M phase cell cycle arrest in MIA PaCa-2 cells. Suppressive effects of regucalcin on cell proliferation were independent of cell death. Overexpression of regucalcin was found to suppress signaling pathways including Akt, MAP kinase and SAPK/JNK, to increase the protein levels of p53, a tumor suppresser, and to decrease K-ras, c-fos and c-jun, a oncogene, by suppressing signaling pathways that are related to signaling of K-ras. Regucalcin may play a potential role as a suppressor protein in human pancreatic cancer. PMID:26935290

  20. NLP-1: a DNA intercalating hypoxic cell radiosensitizer and cytotoxin

    SciTech Connect

    Panicucci, R.; Heal, R.; Laderoute, K.; Cowan, D.; McClelland, R.A.; Rauth, A.M.

    1989-04-01

    The 2-nitroimidazole linked phenanthridine, NLP-1 (5-(3-(2-nitro-1-imidazoyl)-propyl)-phenanthridinium bromide), was synthesized with the rationale of targeting the nitroimidazole to DNA via the phenanthridine ring. The drug is soluble in aqueous solution (greater than 25 mM) and stable at room temperature. It binds to DNA with a binding constant 1/30 that of ethidium bromide. At a concentration of 0.5 mM, NLP-1 is 8 times more toxic to hypoxic than aerobic cells at 37 degrees C. This concentration is 40 times less than the concentration of misonidazole, a non-intercalating 2-nitroimidazole, required for the same degree of hypoxic cell toxicity. The toxicity of NLP-1 is reduced at least 10-fold at 0 degrees C. Its ability to radiosensitize hypoxic cells is similar to misonidazole at 0 degrees C. Thus the putative targeting of the 2-nitroimidazole, NLP-1, to DNA, via its phenanthridine group, enhances its hypoxic toxicity, but not its radiosensitizing ability under the present test conditions. NLP-1 represents a lead compound for intercalating 2-nitroimidazoles with selective toxicity for hypoxic cells.

  1. Radiosensitivity of testicular cells in the prepubertal mouse

    SciTech Connect

    Vergouwen, R.P.F.A.; Roepers-Gajadien, H.L.; Rooij, D.G. de; Eerdenburg, F.J.C.M. van; Huiskamp, R.; Bas, R.J.; Jong, F.H. de; Davids, J.A.G.

    1994-09-01

    The effects of total-body X-irradiation on the prepubertal testis of the CBA/P mouse have been studied. At either day 14 or day 29 post partum male mice were exposed to single doses of X-rays ranging from 15-6.0 Gy. At 1 week after irradiation the repopulation index method was used to study the radiosensitivity of the spermatogonial stem cells. A D{sub 0} value of 1.8 Gy was determined for the stem cells at day 14 post partum as well as for the stem cells at day 29 post partum, indicating that the radiosensitivity of the spermatogonial stem cells in the prepubertal mouse testis is already comparable to that observed in the adult mouse. One, 2 or 3 weeks after irradiation total cell number per testis of Sertoli cells, Leydig cells, mesenchymal cells, macrophages, myoid cells, lymphatic endothelial cells, endothelium and perivascular cells were determined using the disector method. The Sertoli cells and interstitial cell types appeared to be relatively radioresistant during the prepubertal period. No significant changes in plasma testosterone levels were found, indicating that there is no Leydig cell dysfunction after exposure to doses up to 6 Gy during the prepubertal period. Taken together, the radioresponse of the prepubertal mouse testis is comparable to that of the adult mouse testis. 38 refs., 6 figs., 1 tab.

  2. Advances in radiation biology: Radiosensitization in DNA and living cells

    NASA Astrophysics Data System (ADS)

    Lacombe, S.; Sech, C. Le

    2009-06-01

    One fundamental goal of radiation biology is the evolution of concepts and methods for the elaboration of new approaches and protocols for the treatment of cancers. In this context, the use of fast ions as ionizing particles offers the advantage of optimizing cell killing inside the tumor whilst preserving the surrounding healthy tissues. One extremely promising strategy investigated recently is the addition of radiosensitizers in the targeted tissue. The optimization of radiotherapy with fast ions implies a multidisciplinary approach to ionizing radiation effects on complex living systems, ranging from studies on single molecules to investigations of entire organisms. In this article we review recent studies on ion induced damages in simple and complex biological systems, from DNA to living cells. The specific aspect of radiosensitization induced by metallic atoms is described. As a fundamental result, the addition of sensitizing compounds with ion irradiation may improve therapeutic index in cancer therapy. In conclusion, new perspectives are proposed based on the experience and contribution of different communities including Surface Sciences, to improve the development of radiation biology.

  3. 5-Fluorouracil modulation of radiosensitivity in cultured human carcinoma cells.

    PubMed

    Smalley, S R; Kimler, B F; Evans, R G

    1991-02-01

    We evaluated conventional pulse exposure versus continuous exposure models of 5-fluorouracil (5-FU) radiosensitization in HT-29 (human colon adenocarcinoma) and DU-145 (human prostate cancer adenocarcinoma) cell lines. Cell survival following treatment with drug and/or radiation was determined by colony formation assays. Radiation was delivered either by itself, approximately midway through a 1-hr exposure to 5-FU (10 micrograms/ml), or at various times following initiation of exposure to 5-FU (0.5 microgram/ml) present throughout the entire period of incubation. Drug concentrations were selected to approximate those achieved in vivo in humans. HT-29 cells showed a plating efficiency of 87% and similar cytotoxicity (survival reduced to 0.57-0.71) for all 5-FU conditions. The Do's of the radiation survival curves were not different for 1 hr of 5-FU exposure versus radiation alone. However, continuous exposure conditions demonstrated statistically significantly different Do's from radiation alone and pulse 5-FU exposure. DU-145 cells displayed a plating efficiency of 17% and cytotoxicities of 0.10-0.91 for the 5-FU conditions. DU-145 cells showed different radiation 5-FU interactions: 5-FU produced statistically significant changes in Do well as the differences between cell lines insofar as their radiosensitization by 5-FU underscore the caution required in extrapolating these radiobiologic models to the clinical setting. PMID:1991680

  4. Radiosensitization in vitro and in vivo by 3-nitrotriazoles

    SciTech Connect

    Shibamoto, Y.; Sakano, K.; Kimura, R.; Nishidai, T.; Nishimoto, S.; Ono, K.; Kagiya, T.; Abe, M.

    1986-07-01

    A series of 3-nitro-1,2,4-triazole derivatives bearing various types of side chain (R) at the N1-position (AK-2000 series) were synthesized and their radiosensitizing effect and toxicity in vitro and in vivo were investigated, in comparison with those of Misonidazole (MISO), SR-2508, and RSU-1069. Of the fifteen 3-nitrotriazoles tested, all had sensitizing effects in vitro on hypoxic V79 cells. Also, all but one had definite effects on solid EMT6/KU and SCCVII tumors in vivo. For many of the triazole compounds, the degree of radiosensitization in vitro and in vivo appeared identical. However, they were generally less efficient, both in vitro and in vivo, than the corresponding 2-nitroimidazoles, whereas their aerobic cytotoxicity and toxicity to mice (LD50/7) were comparable to those of the 2-nitroimidazoles. Considering the sensitizing effect and toxicity, AK-2123 (R = CH/sub 2/CONHC/sub 2/H/sub 4/OCH/sub 3/) may be as useful as MISO, but none of the triazoles have been proved to be superior to SR-2508.

  5. The radiosensitivity index predicts for overall survival in glioblastoma

    PubMed Central

    Ahmed, Kamran A.; Chinnaiyan, Prakash; Fulp, William J.; Eschrich, Steven; Torres-Roca, Javier F.; Caudell, Jimmy J.

    2015-01-01

    We have previously developed a multigene expression model of tumor radiosensitivity (RSI) with clinical validation in multiple cohorts and disease sites. We hypothesized RSI would identify glioblastoma patients who would respond to radiation and predict treatment outcomes. Clinical and array based gene expression (Affymetrix HT Human Genome U133 Array Plate Set) level 2 data was downloaded from the cancer genome atlas (TCGA). A total of 270 patients were identified for the analysis: 214 who underwent radiotherapy and temozolomide and 56 who did not undergo radiotherapy. Median follow-up for the entire cohort was 9.1 months (range: 0.04–92.2 months). Patients who did not receive radiotherapy were more likely to be older (p < 0.001) and of poorer performance status (p < 0.001). On multivariate analysis, RSI is an independent predictor of OS (HR = 1.64, 95% CI 1.08–2.5; p = 0.02). Furthermore, on subset analysis, radiosensitive patients had significantly improved OS in the patients with high MGMT expression (unmethylated MGMT), 1 year OS 84.1% vs. 53.7% (p = 0.005). This observation held on MVA (HR = 1.94, 95% CI 1.19–3.31; p = 0.008), suggesting that RT has a larger therapeutic impact in these patients. In conclusion, RSI predicts for OS in glioblastoma. These data further confirm the value of RSI as a disease-site independent biomarker. PMID:26451615

  6. Role of Natural Radiosensitizers and Cancer Cell Radioresistance: An Update

    PubMed Central

    Sultana, Misbah; Qazi, Aamer; Qazi, Mahmood Husain; Parveen, Gulshan; Waquar, Sulayman; Ashraf, Abdul Basit; Rasool, Mahmood

    2016-01-01

    Cancer originates from genetic mutations accumulation. Cancer stem cells have been depicted as tumorigenic cells that can differentiate and self-renew. Cancer stem cells are thought to be resistant to conventional therapy like chemotherapy and radiation therapy. Radiation therapy and chemotherapy damage carcinomic DNA cells. Because of the ability of cancer stem cells to self-renew and reproduce malignant tumors, they are the subject of intensive research. In this review, CSCs radioresistant mechanisms which include DNA damage response and natural radiosensitizers have been summed up. Reactive oxygen species play an important role in different physiological processes. ROS scavenging is responsible for regulation of reactive oxygen species generation. A researcher has proved that microRNAs regulate tumor radiation resistance. Ionizing radiation does not kill the cancer cells; rather, IR just slows down the signs and symptoms. Ionizing radiation damages DNA directly/indirectly. IR is given mostly in combination with other chemo/radiotherapies. We briefly described here the behavior of cancer stem cells and radioresistance therapies in cancer treatment. To overcome radioresistance in treatment of cancer, strategies like fractionation modification, treatment in combination, inflammation modification, and overcoming hypoxic tumor have been practiced. Natural radiosensitizers, for example, curcumin, genistein, and quercetin, are more beneficial than synthetic compounds. PMID:26998418

  7. Sodium Selenite Radiosensitizes Hormone-Refractory Prostate Cancer Xenograft Tumors but Not Intestinal Crypt Cells In Vivo

    SciTech Connect

    Tian Junqiang; Ning Shouchen; Knox, Susan J.

    2010-09-01

    Purpose: We have previously shown that sodium selenite (SSE) increases radiation-induced cell killing of human prostate carcinoma cells in vitro. In this study we further evaluated the in vivo radiosensitizing effect of SSE in prostate cancer xenograft tumors and normal radiosensitive intestinal crypt cells. Methods and Materials: Immunodeficient (SCID) mice with hormone-independent LAPC-4 (HI-LAPC-4) and PC-3 xenograft tumors (approximately 200 mm{sup 3}) were divided into four groups: control (untreated), radiation therapy (XRT, local irradiation), SSE (2 mg/kg, intraperitoneally, 3 times/week), and XRT plus SSE. The XRT was given at the beginning of the regimen as a single dose of 5 Gy for HI-LAPC-4 tumors and a single dose of 7 Gy followed by a fractional dose of 3 Gy/d for 5 days for PC-3 tumors. The tumor volume was measured 3 times per week. The radiosensitizing effect of SSE on normal intestinal epithelial cells was assessed by use of a crypt cell microcolony assay. Results: In the efficacy study, SSE alone significantly inhibited the tumor growth in HI-LAPC-4 tumors but not PC-3 tumors. Sodium selenite significantly enhanced the XRT-induced tumor growth inhibition in both HI-LAPC-4 and PC-3 tumors. In the toxicity study, SSE did not affect the intestinal crypt cell survival either alone or in combination with XRT. Conclusions: Sodium selenite significantly enhances the effect of radiation on well-established hormone-independent prostate tumors and does not sensitize the intestinal epithelial cells to radiation. These results suggest that SSE may increase the therapeutic index of XRT for the treatment of prostate cancer.

  8. Cytosolic phospholipaseA2 inhibition with PLA-695 radiosensitizes tumors in lung cancer animal models.

    PubMed

    Thotala, Dinesh; Craft, Jeffrey M; Ferraro, Daniel J; Kotipatruni, Rama P; Bhave, Sandeep R; Jaboin, Jerry J; Hallahan, Dennis E

    2013-01-01

    Lung cancer remains the leading cause of cancer deaths in the United States and the rest of the world. The advent of molecularly directed therapies holds promise for improvement in therapeutic efficacy. Cytosolic phospholipase A2 (cPLA2) is associated with tumor progression and radioresistance in mouse tumor models. Utilizing the cPLA2 specific inhibitor PLA-695, we determined if cPLA2 inhibition radiosensitizes non small cell lung cancer (NSCLC) cells and tumors. Treatment with PLA-695 attenuated radiation induced increases of phospho-ERK and phospho-Akt in endothelial cells. NSCLC cells (LLC and A549) co-cultured with endothelial cells (bEND3 and HUVEC) and pre-treated with PLA-695 showed radiosensitization. PLA-695 in combination with irradiation (IR) significantly reduced migration and proliferation in endothelial cells (HUVEC & bEND3) and induced cell death and attenuated invasion by tumor cells (LLC &A549). In a heterotopic tumor model, the combination of PLA-695 and radiation delayed growth in both LLC and A549 tumors. LLC and A549 tumors treated with a combination of PLA-695 and radiation displayed reduced tumor vasculature. In a dorsal skin fold model of LLC tumors, inhibition of cPLA2 in combination with radiation led to enhanced destruction of tumor blood vessels. The anti-angiogenic effects of PLA-695 and its enhancement of the efficacy of radiotherapy in mouse models of NSCLC suggest that clinical trials for its capacity to improve radiotherapy outcomes are warranted. PMID:23894523

  9. Cytosolic PhospholipaseA2 Inhibition with PLA-695 Radiosensitizes Tumors in Lung Cancer Animal Models

    PubMed Central

    Ferraro, Daniel J.; Kotipatruni, Rama P.; Bhave, Sandeep R.; Jaboin, Jerry J.; Hallahan, Dennis E.

    2013-01-01

    Lung cancer remains the leading cause of cancer deaths in the United States and the rest of the world. The advent of molecularly directed therapies holds promise for improvement in therapeutic efficacy. Cytosolic phospholipase A2 (cPLA2) is associated with tumor progression and radioresistance in mouse tumor models. Utilizing the cPLA2 specific inhibitor PLA-695, we determined if cPLA2 inhibition radiosensitizes non small cell lung cancer (NSCLC) cells and tumors. Treatment with PLA-695 attenuated radiation induced increases of phospho-ERK and phospho-Akt in endothelial cells. NSCLC cells (LLC and A549) co-cultured with endothelial cells (bEND3 and HUVEC) and pre-treated with PLA-695 showed radiosensitization. PLA-695 in combination with irradiation (IR) significantly reduced migration and proliferation in endothelial cells (HUVEC & bEND3) and induced cell death and attenuated invasion by tumor cells (LLC &A549). In a heterotopic tumor model, the combination of PLA-695 and radiation delayed growth in both LLC and A549 tumors. LLC and A549 tumors treated with a combination of PLA-695 and radiation displayed reduced tumor vasculature. In a dorsal skin fold model of LLC tumors, inhibition of cPLA2 in combination with radiation led to enhanced destruction of tumor blood vessels. The anti-angiogenic effects of PLA-695 and its enhancement of the efficacy of radiotherapy in mouse models of NSCLC suggest that clinical trials for its capacity to improve radiotherapy outcomes are warranted. PMID:23894523

  10. The Myb-p300-CREB axis modulates intestine homeostasis, radiosensitivity and tumorigenesis

    PubMed Central

    Sampurno, S; Bijenhof, A; Cheasley, D; Xu, H; Robine, S; Hilton, D; Alexander, W S; Pereira, L; Mantamadiotis, T; Malaterre, J; Ramsay, R G

    2013-01-01

    The gastrointestinal (GI) epithelium is constantly renewing, depending upon the intestinal stem cells (ISC) regulated by a spectrum of transcription factors (TFs), including Myb. We noted previously in mice with a p300 mutation (plt6) within the Myb-interaction-domain phenocopied Myb hypomorphic mutant mice with regard to thrombopoiesis, and here, changes in GI homeostasis. p300 is a transcriptional coactivator for many TFs, most prominently cyclic-AMP response element-binding protein (CREB), and also Myb. Studies have highlighted the importance of CREB in proliferation and radiosensitivity, but not in the GI. This prompted us to directly investigate the p300–Myb–CREB axis in the GI. Here, the role of CREB has been defined by generating GI-specific inducible creb knockout (KO) mice. KO mice show efficient and specific deletion of CREB, with no evident compensation by CREM and ATF1. Despite complete KO, only modest effects on proliferation, radiosensitivity and differentiation in the GI under homeostatic or stress conditions were evident, even though CREB target gene pcna (proliferating cell nuclear antigen) was downregulated. creb and p300 mutant lines show increased goblet cells, whereas a reduction in enteroendocrine cells was apparent only in the p300 line, further resembling the Myb hypomorphs. When propagated in vitro, crebKO ISC were defective in organoid formation, suggesting that the GI stroma compensates for CREB loss in vivo, unlike in MybKO studies. Thus, it appears that p300 regulates GI differentiation primarily through Myb, rather than CREB. Finally, active pCREB is elevated in colorectal cancer (CRC) cells and adenomas, and is required for the expression of drug transporter, MRP2, associated with resistance to Oxaliplatin as well as several chromatin cohesion protein that are relevant to CRC therapy. These data raise the prospect that CREB may have a role in GI malignancy as it does in other cancer types, but unlike Myb, is not critical for GI

  11. Diffusion-weighted magnetic resonance imaging in predicting the radiosensitivity of cervical cancer

    PubMed Central

    Ni, Xiaolei; Tong, Yuanhe; Xiao, Youping; Liao, Jiang; Chen, Yunbing; Wang, Min

    2015-01-01

    This study investigates the application value of diffusion-weighted magnetic resonance imaging in predicting cervical cancer radiosensitivity. Twenty-five patients who were newly diagnosed as cervical cancer and accepted simple radiotherapy were included in this study. Before external irradiation, 20 GY and at the end of irradiation, routine 1.5 T MRI and diffusion-weighted magnetic resonance imaging scanning were carried. Apparent diffusion coefficient (ADC) value of primary tumor was measured. Its correlation with tumor regression rate was analyzed. ADC values of before irradiation, 20 GY and at the end of irradiation was (0.93 ± 0.14) × 10-3 mm2/s, (1.25 ± 0.17) × 10-3 mm2/s and (1.55 ± 0.13) × 10-3 mm2/s, respectively. There were statistical significant differences (P< 0.01). D-value of ADC values between before and 20 GY external irradiation was (0.33 ± 0.16) mm2/s. The tumor volume before and at the end of external irradiation were (37.48 ± 26.83) cm3 and (4.41 ± 3.72) cm3 respectively, with tumor regression rate of before and after external irradiation of (0.86 ± 0.11). ADC values of before irradiation, 20 GY and at the end of irradiation did not correlate with tumor regression rate. D-value of ADC values between before and 20 GY external irradiation positively correlated with tumor regression rate (r = 0.423, P = 0.035). ADC value of cervical cancer increased after radiotherapy and early changes of ADC value was positively correlated with tumor regression rate, thus, ADC value could be used as a potential prediction factor for cervical cancer radiosensitivity. PMID:26550334

  12. Stereotactic Ablative Radiotherapy Should Be Combined With a Hypoxic Cell Radiosensitizer

    SciTech Connect

    Brown, J. Martin; Diehn, Maximilian; Loo, Billy W.

    2010-10-01

    Purpose: To evaluate the effect of tumor hypoxia on the expected level of cell killing by regimens of stereotactic ablative radiotherapy (SABR) and to determine the extent to which the negative effect of hypoxia could be prevented using a clinically available hypoxic cell radiosensitizer. Results and Discussion: We have calculated the expected level of tumor cell killing from regimens of SABR, both with and without the assumption that 20% of the tumor cells are hypoxic, using the standard linear quadratic model and the universal survival curve modification. We compare the results obtained with our own clinical data for lung tumors of different sizes and with published data from other studies. We also have calculated the expected effect on cell survival of adding the hypoxic cell sensitizer etanidazole at clinically achievable drug concentrations. Modeling tumor cell killing with any of the currently used regimens of SABR produces results that are inconsistent with the majority of clinical findings if tumor hypoxia is not considered. However, with the assumption of tumor hypoxia, the expected level of cell killing is consistent with clinical data. For only some of the smallest tumors are the clinical data consistent with no tumor hypoxia, but there could be other reasons for the sensitivity of these tumors. The addition of etanidazole at clinically achievable tumor concentrations produces a large increase in the expected level of tumor cell killing from the large radiation doses used in SABR. Conclusions: The presence of tumor hypoxia is a major negative factor in limiting the curability of tumors by SABR at radiation doses that are tolerable to surrounding normal tissues. However, this negative effect of hypoxia could be overcome by the addition of clinically tolerable doses of the hypoxic cell radiosensitizer etanidazole.

  13. Antisense inhibition of cyclin D1 expression is equivalent to flavopiridol for radiosensitization of zebrafish embryos

    SciTech Connect

    McAleer, Mary Frances; Duffy, Kevin T.; Davidson, William R.; Kari, Gabor; Dicker, Adam P.; Rodeck, Ulrich; Wickstrom, Eric . E-mail: eric@tesla.jci.tju.edu

    2006-10-01

    Purpose: Flavopiridol, a small molecule pan-cyclin inhibitor, has been shown to enhance Radiation response of tumor cells both in vitro and in vivo. The clinical utility of flavopiridol, however, is limited by toxicity, previously attributed to pleiotropic inhibitory effects on several targets affecting multiple signal transduction pathways. Here we used zebrafish embryos to investigate radiosensitizing effects of flavopiridol in normal tissues. Methods and Materials: Zebrafish embryos at the 1- to 4-cell stage were treated with 500 nM flavopiridol or injected with 0.5 pmol antisense hydroxylprolyl-phosphono nucleic acid oligomers to reduce cyclin D1 expression, then subjected to ionizing radiation (IR) or no radiation. Results: Flavopiridol-treated embryos demonstrated a twofold increase in mortality after exposure to 40 Gy by 96 hpf and developed distinct radiation-induced defects in midline development (designated as the 'curly up' phenotype) at higher rates when compared with embryos receiving IR only. Cyclin D1-deficient embryos had virtually identical IR sensitivity profiles when compared with embryos treated with flavopiridol. This was particularly evident for the IR-induced curly up phenotype, which was greatly exacerbated by both flavopriridol and cyclin D1 downregulation. Conclusions: Treatment of zebrafish embryos with flavopiridol enhanced radiation sensitivity of zebrafish embryos to a degree that was very similar to that associated with downregulation of cyclin D1 expression. These results are consistent with the hypothesis that inhibition of cyclin D1 is sufficient to account for the radiosensitizing action of flavopiridol in the zebrafish embryo vertebrate model.

  14. Hyperthermic killing and hyperthermic radiosensitization in Chinese hamster ovary cells: effects of pH and thermal tolerance

    SciTech Connect

    Holahan, E.V.; Highfield, D.P.; Holahan, P.K.; Dewey, W.C.

    1984-01-01

    To quantitatively relate heat killing and heat radiosensitization, asynchronous or G/sub 1/ Chinese hamster ovary (CHO) at pH 7.1 or 6.75 were heated and/or X-irradiated 10 min. later. Since no progression of G/sub 1/cells into S phase occurred during the heat and radiation treatments, cell cycle artifacts were minimized. Hyperthermic radiosensitizaiton was expressed as the thermal enhancement factor (TEF), defined as the ratio of the D/sub 0/ of the radiation survival curve to that of the D/sub 0/ radiation survival curve for heat plus radiation. The TEF increased continuously with increased of the heat killing at 45.5/sup 0/ C, and for a given amount of heat killing, the amount of heat radiosensitization was the same for both pH's. When cells were heated chronically at 42.4/sup 0/ C at pH 7.4, the TEF increased initially to 2.0-2.5 and then returned to near 1.0 during continued heating as thermal tolerance developed for both heat killing and heat radiosensitization. However, the shoulder (D/sub q/) of the radiation survival curve for heat plus radiation did not manifest thermal tolerance. These results suggest that heat killing and heat radiosensitization have a target(s) in common (TEF results), along with either a different target(s) or a difference in the manifestation of heat damage (D/sub q/ results). Since low pH reduced the rate of development of thermal tolerance during heating at low temperatures, low pH enhanced heat killing more at 42-42.5/sup 0/ C than at 45.5 C where thermal tolerance did not develop. These findings agree with animal experiments suggesting that in the clinic, a therapeutic gain for tumor cells at low pH may be greater for temperatures of 42-42.5/sup 0/ C than of 45.5/sup 0/ C.

  15. MiR-593 mediates curcumin-induced radiosensitization of nasopharyngeal carcinoma cells via MDR1

    PubMed Central

    FAN, HAONING; SHAO, MENG; HUANG, SHAOHUI; LIU, YING; LIU, JIE; WANG, ZHIYUAN; DIAO, JIANXIN; LIU, YUANLIANG; TONG, LI; FAN, QIN

    2016-01-01

    Curcumin (Cur) exhibits radiosensitization effects to a variety of malignant tumors. The present study investigates the radiosensitizing effect of Cur on nasopharyngeal carcinoma (NPC) cells and whether its mechanism is associated with microRNA-593 (miR-593) and multidrug resistance gene 1 (MDR1). A clonogenic assay was performed to measure the radiosensitizing effect. The expression of miR-593 and MDR1 was analyzed by quantitative polymerase chain reaction (qPCR) or western blot assay. A transplanted tumor model was established to identify the radiosensitizing effect in vivo. A luciferase-based reporter was constructed to evaluate the effect of direct binding of miR-593 to the putative target site on the 3′ UTR of MDR1. The clonogenic assay showed that Cur enhanced the radiosensitivity of cells. Cur (100 mg/kg) combined with 4 Gy irradiation inhibited the growth of a transplanted tumor model in vivo, resulting in the higher inhibition ratio compared with the radiotherapy-alone group. These results demonstrated that Cur had a radiosensitizing effect on NPC cells in vivo and in vitro; Cur-mediated upregulation of miR-593 resulted in reduced MDR1 expression, which may promote radiosensitivity of NPC cells. PMID:27313684

  16. Isotype-Specific Inhibition of Histone Deacetylases: Identification of Optimal Targets for Radiosensitization

    PubMed Central

    Kim, Jin Ho; Moon, Sung Ho; No, Mina; Kim, Jae Jin; Choi, Eun Jung; Cho, Bong Jun; Kim, Jae Sung; Kim, Il Han; Kim, In Ah

    2016-01-01

    Purpose Histone deacetylase (HDAC) inhibitors radiosensitize tumor cells. To elucidate mechanisms underlying radiosensitization by HDAC inhibition, understanding of differential contributions of HDAC isotypes is needed. The aim of this study was to investigate involvement of known HDAC isotypes in modulation of cellular radiosensitivity. Materials and Methods Because pharmacologic HDAC inhibitors lack isotype-specificity, RNA interference against 11 HDAC isotypes was used to inhibit HDAC in an isotype-specific manner. Radiation cell survival was evaluated using a clonogenic assay in SQ20B cells transfected with small interfering RNA specifically targeting HDAC isotypes. Immunocytochemistry was performed for detection of γH2AX foci. Protein expression was measured using Western blotting. Results Among 11 HDAC isotypes tested, specific inhibition of 7 isotypes (HDAC1, HDAC3, HDAC4, HDAC6, HDAC7, HDAC10, and HDAC11) enhanced radiation lethality in SQ20B cells. Radiosensitization by inhibition of these HDAC isotypes was accompanied by delay of DNA double strand break repair. Radiosensitivity of SQ20B cells was not altered by selective inhibition of the remaining four isotypes (HDAC2, HDAC5, HDAC8, and HDAC9). Inhibition of HDAC isotypes resulted in downregulation of various proteins involved in pro-survival and DNA damage repair pathways. Conclusion Isotype-specificity exists in HDAC inhibition-induced radiosensitization. Different HDAC isotypes are differentially involved in modulation of cellular radiosensitivity. PMID:26582395

  17. On differences in radiosensitivity estimation: TCP experiments versus survival curves. A theoretical study

    NASA Astrophysics Data System (ADS)

    Stavrev, Pavel; Stavreva, Nadejda; Ruggieri, Ruggero; Nahum, Alan

    2015-08-01

    We have compared two methods of estimating the cellular radiosensitivity of a heterogeneous tumour, namely, via cell-survival and via tumour control probability (TCP) pseudo-experiments. It is assumed that there exists intra-tumour variability in radiosensitivity and that the tumour consists predominantly of radiosensitive cells and a small number of radio-resistant cells. Using a multi-component, linear-quadratic (LQ) model of cell kill, a pseudo-experimental cell-survival versus dose curve is derived. This curve is then fitted with a mono-component LQ model describing the response of a homogeneous cell population. For the assumed variation in radiosensitivity it is shown that the composite pseudo-experimental survival curve is well approximated by the survival curve of cells with uniform radiosensitivity. For the same initial cell radiosensitivity distribution several pseudo-experimental TCP curves are simulated corresponding to different fractionation regimes. The TCP model used accounts for clonogen proliferation during a fractionated treatment. The set of simulated TCP curves is then fitted with a mono-component TCP model. As in the cell survival experiment the fit with a mono-component model assuming uniform radiosensitivity is shown to be highly acceptable. However, the best-fit values of cellular radiosensitivity produced via the two methods are very different. The cell-survival pseudo-experiment yields a high radiosensitivity value, while the TCP pseudo-experiment shows that the dose-response is dominated by the most resistant sub-population in the tumour, even when this is just a small fraction of the total.

  18. Enhancement of radiosensitization by metal-based nanoparticles in cancer radiation therapy

    PubMed Central

    Su, Xiang-Yu; Liu, Pei-Dang; Wu, Hao; Gu, Ning

    2014-01-01

    Radiation therapy performs an important function in cancer treatment. However, resistance of tumor cells to radiation therapy still remains a serious concern, so the study of radiosensitizers has emerged as a persistent hotspot in radiation oncology. Along with the rapid advancement of nanotechnology in recent years, the potential value of nanoparticles as novel radiosensitizers has been discovered. This review summarizes the latest experimental findings both in vitro and in vivo and attempts to highlight the underlying mechanisms of response in nanoparticle radiosensitization. PMID:25009750

  19. Cooperative effect of BI-69A11 and celecoxib enhances radiosensitization by modulating DNA damage repair in colon carcinoma.

    PubMed

    Pal, Ipsita; Dey, Kaushik Kumar; Chaurasia, Madhuri; Parida, Sheetal; Das, Subhayan; Rajesh, Y; Sharma, Kulbhushan; Chowdhury, Tamohan; Mandal, Mahitosh

    2016-05-01

    Amplification of PI3K-Akt pathway promotes radioresistance in various cancers including colorectal carcinoma. Local recurrence in colon cancer causes poor prognosis affecting overall survival of cancer-affected patient population. To avoid local recurrence, pre-operative or post-operative additional radiotherapy is given. However, main concern regarding radiotherapy is to increase the radiosensitivity of malignant cell without hampering the activities of normal cells. In this context, addition of two or more than two chemotherapeutic drugs as a radiosensitizer is a common practice in radiation biology. BI-69A11 earlier showed potential apoptosis-inducing effect in melanoma and colon carcinoma. Celecoxib showed anti-cancer effects in both COX-2 dependent and independent pathways and used to act as a radiosensitizing enhancer. Here, we suggest that the combination of BI-69A11 and celecoxib inhibits the phosphorylation of ataxia telangiectasia mutated (ATM) kinase and DNA-PK responsible for ionizing radiation (IR)-induced double-strand break (DSB) repair. Moreover, the combinatorial effect of BI-69A11 and celecoxib attenuates the IR-induced G2/M cell cycle arrest. Furthermore, this combination also impairs IR-induced activation of Akt and downstream targets of ATM. This might lead to induced activation of apoptotic pathway after triple therapy treatment modulating pro-apoptotic and anti-apoptotic proteins. This activation of apoptotic pathway also showed the interdependence of PUMA and BAD in triple combination-treated colon cancer cells in a p53 independent manner. This study reveals the therapeutic potential of the triple combination therapy in prevention of radioresistance. Besides, it also demonstrates the cytotoxic effects of triple combination therapy in colon cancer. This study shows utility and potential implication on safety of the patients undergoing radiation therapy. PMID:26631035

  20. Targeted radiosensitization with PARP1 inhibition: optimization of therapy and identification of biomarkers of response in breast cancer.

    PubMed

    Feng, Felix Y; Speers, Corey; Liu, Meilan; Jackson, William C; Moon, Dominic; Rinkinen, Jacob; Wilder-Romans, Kari; Jagsi, Reshma; Pierce, Lori J

    2014-08-01

    Sustained locoregional control of breast cancer is a significant issue for certain patients. Inhibition of PARP1 is a promising strategy for radiosensitization (RS). We sought to optimize therapy with PARP1 inhibition and radiation (RT) by establishing the most effective treatment schedule, degree of PARP1-mediated RS, and identify early biomarkers predictive of efficacy in breast cancer models. Using clonogenic survival assays, we assessed intrinsic radiosensitivity and RS induced by PARP1 inhibition in breast cancer cell lines. Potential biomarkers of response were evaluated using western blotting, flow cytometry, and immunofluorescence with validation in vivo using tumor xenograft experiments. Across a panel of BC and normal breast epithelial cell lines, the PARP1 inhibitor ABT-888 preferentially radiosensitizes breast cancer (vs. normal) cells with enhancement ratios (EnhR) up to 2.3 independent of intrinsic BC subtype or BRCA mutational status. Concurrent and adjuvant therapy resulted in the highest EnhR of all schedules tested. The degree of RS did not correlate with pretreatment markers of PARP1 activity, DNA damage/repair, or cell cycle distribution. Increases in PARP1 activity 24 h after RT were associated with sensitivity after combination treatment. Findings were confirmed in breast cancer xenograft models. Our study demonstrates that PARP1 inhibition improves the therapeutic index of RT independent of BC subtype or BRCA1 mutational status and that PARP1 activity may serve as a clinically relevant biomarker of response. These studies have led to a clinical trial (TBCRC024) incorporating intratreatment biomarker analyses of PARP1 inhibitors and RT in breast cancer patients. PMID:25104443

  1. Autotaxin and LPA Receptors Represent Potential Molecular Targets for the Radiosensitization of Murine Glioma through Effects on Tumor Vasculature

    PubMed Central

    Linkous, Amanda G.; Hu, Rong; Leahy, Kathleen M.; Yazlovitskaya, Eugenia M.; Hallahan, Dennis E.

    2011-01-01

    Despite wide margins and high dose irradiation, unresectable malignant glioma (MG) is less responsive to radiation and is uniformly fatal. We previously found that cytosolic phospholipase A2 (cPLA2) is a molecular target for radiosensitizing cancer through the vascular endothelium. Autotaxin (ATX) and lysophosphatidic acid (LPA) receptors are downstream from cPLA2 and highly expressed in MG. Using the ATX and LPA receptor inhibitor, α-bromomethylene phosphonate LPA (BrP-LPA), we studied ATX and LPA receptors as potential molecular targets for the radiosensitization of tumor vasculature in MG. Treatment of Human Umbilical Endothelial cells (HUVEC) and mouse brain microvascular cells bEND.3 with 5 µmol/L BrP-LPA and 3 Gy irradiation showed decreased clonogenic survival, tubule formation, and migration. Exogenous addition of LPA showed radioprotection that was abrogated in the presence of BrP-LPA. In co-culture experiments using bEND.3 and mouse GL-261 glioma cells, treatment with BrP-LPA reduced Akt phosphorylation in both irradiated cell lines and decreased survival and migration of irradiated GL-261 cells. Using siRNA to knock down LPA receptors LPA1, LPA2 or LPA3 in HUVEC, we demonstrated that knockdown of LPA2 but neither LPA1 nor LPA3 led to increased viability and proliferation. However, knockdown of LPA1 and LPA3 but not LPA2 resulted in complete abrogation of tubule formation implying that LPA1 and LPA3 on endothelial cells are likely targets of BrP-LPA radiosensitizing effect. Using heterotopic tumor models of GL-261, mice treated with BrP-LPA and irradiation showed a tumor growth delay of 6.8 days compared to mice treated with irradiation alone indicating that inhibition of ATX and LPA receptors may significantly improve malignant glioma response to radiation therapy. These findings identify ATX and LPA receptors as molecular targets for the development of radiosensitizers for MG. PMID:21799791

  2. Dissociative electron attachment to the radiosensitizing chemotherapeutic agent hydroxyurea.

    PubMed

    Huber, S E; Śmiałek, M A; Tanzer, K; Denifl, S

    2016-06-14

    Dissociative electron attachment to hydroxyurea was studied in the gas phase for electron energies ranging from zero to 9 eV in order to probe its radiosensitizing capabilities. The experiments were carried out using a hemispherical electron monochromator coupled with a quadrupole mass spectrometer. Diversified fragmentation of hydroxyurea was observed upon low energy electron attachment and here we highlight the major dissociation channels. Moreover, thermodynamic thresholds for various fragmentation reactions are reported to support the discussion of the experimental findings. The dominant dissociation channel, which was observed over a broad range of energies, is associated with formation of NCO(-), water, and the amidogen (NH2) radical. The second and third most dominant dissociation channels are associated with formation of NCNH(-) and NHCONH2 (-), respectively, which are both directly related to formation of the highly reactive hydroxyl radical. Other ions observed with significant abundance in the mass spectra were NH2 (-)/O(-), OH(-), CN(-), HNOH(-), NCONH2 (-), and ONHCONH2 (-). PMID:27306009

  3. Dissociative electron attachment to the radiosensitizing chemotherapeutic agent hydroxyurea

    NASA Astrophysics Data System (ADS)

    Huber, S. E.; Śmiałek, M. A.; Tanzer, K.; Denifl, S.

    2016-06-01

    Dissociative electron attachment to hydroxyurea was studied in the gas phase for electron energies ranging from zero to 9 eV in order to probe its radiosensitizing capabilities. The experiments were carried out using a hemispherical electron monochromator coupled with a quadrupole mass spectrometer. Diversified fragmentation of hydroxyurea was observed upon low energy electron attachment and here we highlight the major dissociation channels. Moreover, thermodynamic thresholds for various fragmentation reactions are reported to support the discussion of the experimental findings. The dominant dissociation channel, which was observed over a broad range of energies, is associated with formation of NCO-, water, and the amidogen (NH2) radical. The second and third most dominant dissociation channels are associated with formation of NCNH- and NHCONH2-, respectively, which are both directly related to formation of the highly reactive hydroxyl radical. Other ions observed with significant abundance in the mass spectra were NH2-/O-, OH-, CN-, HNOH-, NCONH2-, and ONHCONH2-.

  4. Radiosensitivity Parameters For Lethal Mutagenesis In Caenorhabditis Elegans

    SciTech Connect

    Cucinotta, F.A.; Wilson, J.W.; Katz, R.

    1994-01-01

    For the first time track structure theory has been applied to radiobiological effects in a living organism. Data for lethal mutagenesis in Caenorhabditis elegans, obtained after irradiation with nine different types of ions of atomic number 1-57 and gamma rays have yielded radiosensitivity parameters (E{sub 0}, sigma{sub 0}, Kappa, m = 68 Gy, 2.5 x 10(exp {minus}9) cm (exp 2), 750, 2) comparable with those found for the transformation of C3HT10 1/2 cells (180 Gy, 1.15 x 10(exp {minus}10) cm(exp 2), 750, 2) but remote from those (E{sub 0} and sigma{sub 0} = approx. 2 Gy, approx. 5 x 10(exp {minus}7) cm(exp 2)) for mammalian cell survival.

  5. Enhanced radiation therapy with multilayer microdisks containing radiosensitizing gold nanoparticles.

    PubMed

    Zhang, Peipei; Qiao, Yong; Xia, Junfei; Guan, Jingjiao; Ma, Liyuan; Su, Ming

    2015-03-01

    A challenge of X-ray radiation therapy is that high dose X-rays at therapeutic conditions damage normal cells. This paper describes the use of gold nanoparticle-loaded multilayer microdisks to enhance X-ray radiation therapy, where each microdisk contains over 10(5) radiosensitizing nanoparticles. The microdisks are attached on cell membranes through electrostatic interaction. Upon X-ray irradiation, more photoelectrons and Auger electrons are generated in the vicinity of the nanoparticles, which cause water ionization and lead to the formation of free radicals that damage the DNA of adjacent cancer cells. By attaching a large amount of gold nanoparticles on cancer cells, the total X-ray dose required for DNA damage and cell killing can be reduced. Due to their controllable structure and composition, multilayer microdisks can be a viable choice for enhanced radiation therapy with nanoparticles. PMID:25679345

  6. Validation of a Radiosensitivity Molecular Signature in Breast Cancer

    PubMed Central

    Eschrich, Steven A.; Fulp, William J.; Pawitan, Yudi; Foekens, John A.; Smid, Marcel; Martens, John W. M.; Echevarria, Michelle; Kamath, Vidya; Lee, Ji-Hyun; Harris, Eleanor E.; Bergh, Jonas; Torres-Roca, Javier F.

    2014-01-01

    Purpose Previously, we developed a radiosensitivity molecular signature (RSI) that was clinically-validated in three independent datasets (rectal, esophageal, head and neck) in 118 patients. Here, we test RSI in radiotherapy (RT) treated breast cancer patients. Experimental Design RSI was tested in two previously published breast cancer datasets. Patients were treated at the Karolinska University Hospital (n=159) and Erasmus Medical Center (n=344). RSI was applied as previously described. Results We tested RSI in RT-treated patients (Karolinska). Patients predicted to be radiosensitive (RS) had an improved 5 yr relapse-free survival when compared with radioresistant (RR) patients (95% vs. 75%, p=0.0212) but there was no difference between RS/RR patients treated without RT (71% vs. 77%, p=0.6744), consistent with RSI being RT-specific (interaction term RSIxRT, p=0.05). Similarly, in the Erasmus dataset RT-treated RS patients had an improved 5-year distant-metastasis-free survival over RR patients (77% vs. 64%, p=0.0409) but no difference was observed in patients treated without RT (RS vs. RR, 80% vs. 81%, p=0.9425). Multivariable analysis showed RSI is the strongest variable in RT-treated patients (Karolinska, HR=5.53, p=0.0987, Erasmus, HR=1.64, p=0.0758) and in backward selection (removal alpha of 0.10) RSI was the only variable remaining in the final model. Finally, RSI is an independent predictor of outcome in RT-treated ER+ patients (Erasmus, multivariable analysis, HR=2.64, p=0.0085). Conclusions RSI is validated in two independent breast cancer datasets totaling 503 patients. Including prior data, RSI is validated in five independent cohorts (621 patients) and represents, to our knowledge, the most extensively validated molecular signature in radiation oncology. PMID:22832933

  7. Expression of hPNAS-4 Radiosensitizes Lewis Lung Cancer

    SciTech Connect

    Zeng Hui; Yuan Zhu; Zhu Hong; Li Lei; Shi Huashan; Wang Zi; Fan Yu; Deng Qian; Zeng Jianshuang; He Yinbo; Xiao Jianghong; Li Zhiping

    2012-11-15

    Purpose: This study aimed to transfer the hPNAS-4 gene, a novel apoptosis-related human gene, into Lewis lung cancer (LL2) and observe its radiosensitive effect on radiation therapy in vitro and in vivo. Methods and Materials: The hPNAS-4 gene was transfected into LL2 cells, and its expression was detected via western blot. Colony formation assay and flow cytometry were used to detect the growth and apoptosis of cells treated with irradiation/PNAS-4 in vitro. The hPNAS-4 gene was transferred into LL2-bearing mice through tail vein injection of the liposome/gene complex. The tumor volumes were recorded after radiation therapy. Proliferating cell nuclear antigen (PCNA) immunohistochemistry staining and terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) assay were performed to detect the tumor cell growth and apoptosis in vivo. Results: The hPNAS-4 gene was successfully transferred into LL2 cells and tumor tissue, and its overexpressions were confirmed via western blot analysis. Compared with the control, empty plasmid, hPNAS-4, radiation, and empty plasmid plus radiation groups, the hPNAS-4 plus radiation group more significantly inhibited growth and enhanced apoptosis of LL2 cells in vitro and in vivo (P<.05). Conclusions: The hPNAS-4 gene was successfully transferred into LL2 cells and tumor tissue and was expressed in both LL2 cell and tumor tissue. The hPNAS-4 gene therapy significantly enhanced growth inhibition and apoptosis of LL2 tumor cells by radiation therapy in vitro and in vivo. Therefore, it may be a potential radiosensitive treatment of radiation therapy for lung cancer.

  8. Terameprocol (tetra-O-methyl nordihydroguaiaretic acid), an inhibitor of Sp1-mediated survivin transcription, induces radiosensitization in non-small cell lung carcinoma

    PubMed Central

    Sun, Yunguang; Giacalone, Nicholas J.; Lu, Bo

    2010-01-01

    Introduction Survivin, an inhibitor of apoptosis protein (IAP) and key regulator of mitosis, is up-regulated in a variety of cancers and is often associated with a worse prognosis. Terameprocol down-regulates the Sp1-mediated transcription of survivin and Cdk1, which is important for cell cycle progression, as well as many other proteins. Survivin inhibition has previously been shown to result in the induction of apoptosis and radiosensitization. Methods This study examined the effects of terameprocol administration on survivin transcription and expression in HCC2429 and H460 lung cancer cells. We also examined the combined effects of radiation and terameprocol on apoptosis and radiosensitivity. Results Using immunoblot analysis and luciferase assays, we confirmed that terameprocol decreases survivin transcription and protein expression. Ultimately, however, decreases in survivin expression failed to correlate with an increase in apoptosis. Nonetheless, clonogenic assay revealed that terameprocol induces increased radiosensitization in HCC2429 (DER = 1.26, p = 0.019) and H460 (DER = 1.18, p = 0.001) cells. Additionally, the data show no effect of terameprocol on cell cycle in either HCC2429 or H460 cells. Conclusions Terameprocol significantly enhances the sensitivity of non-small cell lung carcinoma cell lines to radiation therapy, although the mechanism of action remains unclear. Further study is warranted to assess the potential of terameprocol as an agent that may enhance the therapeutic ratio of radiotherapy in lung cancer. PMID:21107289

  9. TGF-B3 Dependent Modification of Radiosensitivity in Reporter Cells Exposed to Serum From Whole-Body Low Dose-Rate Irradiated Mice.

    PubMed

    Edin, Nina Jeppesen; Altaner, Čestmír; Altanerova, Veronica; Ebbesen, Peter

    2015-01-01

    Prior findings in vitro of a TGF-β3 dependent mechanism induced by low dose-rate irradiation and resulting in increased radioresistance and removal of low dose hyper-radiosensitivity (HRS) was tested in an in vivo model. DBA/2 mice were given whole-body irradiation for 1 h at low dose-rates (LDR) of 0.3 or 0.03 Gy/h. Serum was harvested and added to RPMI (4% mouse serum and 6% bovine serum).This medium was transferred to reporter cells (T-47D breast cancer cells or T98G glioblastoma cells). The response to subsequent challenge irradiation of the reporter cells was measured by the colony assay. While serum from unirradiated control mice had no effect on the radiosensitivity in the reporter cells, serum from mice given 0.3 Gy/h or 0.03 Gy/h for 1 h removed HRS and also increased survival in response to doses up to 5 Gy. The effect lasted for at least 15 months after irradiation. TGF-β3 neutralizer added to the medium containing mouse serum inhibited the effect. Serum from mice given irradiation of 0.3 Gy/h for 1 h and subsequently treated with iNOS inhibitor 1400W did not affect radiosensitivity in reporter cells; neither did serum from the unirradiated progeny of mice given 1h LDR whole-body irradiation. PMID:26673923

  10. Six Degrees of Separation: The Oxygen Effect in the Development of Radiosensitizers

    PubMed Central

    Oronsky, Bryan T; Knox, Susan J; Scicinski, Jan

    2011-01-01

    The popular theory six degrees of separation is used in this review as an analogy to relate all radiosensitization to oxygen. As the prime mover of all radiosensitizers, the pervasive influence of oxygen has consciously or unconsciously influenced the direction of research and development and provided the benchmark against which all other compounds and approaches are measured. It is the aim of this review to develop the six degrees of separation from oxygen analogy as a unifying framework for conceptually organizing the field and for giving context to its varied subspecializations and theories. Under such a framework, it would become possible for one area to consider questions and problems found in other areas of radiosensitization, using a common analogy, that would allow for further development and unification of this multifaceted discipline. In this review, approaches to the development of radiosensitizers and the current state of research in this field are discussed, including promising new agents in various stages of clinical development. PMID:21804913

  11. Is Nitric Oxide (NO) the Last Word in Radiosensitization? A Review

    PubMed Central

    Oronsky, Bryan T; Knox, Susan J; Scicinski, Jan J

    2012-01-01

    As a short-lived radical that diffuses across membranes, rather than interacting with membrane-bound receptors, nitric oxide (NO) represents a significant departure from synthetically derived radiosensitizers. An endogenous compound, NO may equal or surpass its molecular cousin, oxygen, as a hypoxic radiosensitizer, through pleiotropic phenotypic effects on tumor perfusion, cell signaling, mitochondrial respiration, the fixation of radiation-induced damage, and the radioprotection of normal tissue. However, unlike oxygen, in the context of radiosensitization, the clinical role and utility of NO are poorly understood, with often contradictory and controversial reported effects: whether NO functions as a radiosensitizer may ultimately be contextual to the tumor microenvironment. This may make NO manipulation an ideal candidate for a personalized radiosensitization approach tailored to specific patient and tumor types/microenvironmental characteristics. Effective delivery of NO both systemically and directly to the tumor may be critical to the success of this approach. Compounds that release NO or NO precursors have the potential to drive innovation and result in a new fertile branch of the radiosensitizer tree. PMID:22496921

  12. Re-evaluating gadolinium(III) texaphyrin as a radiosensitizing agent.

    PubMed

    Bernhard, E J; Mitchell, J B; Deen, D; Cardell, M; Rosenthal, D I; Brown, J M

    2000-01-01

    Gadolinium(III) texaphyrin (Gd-tex) was recently proposed as a radiosensitizing agent that combines preferential tumor uptake with detection of drug localization by magnetic resonance imaging (S. W. Young et al., Proc. Natl. Acad. Sci. USA, 93: 6610-6615, 1996). In view of the initial report on this compound, four radiobiology laboratories undertook independent efforts to further study radiosensitization by Gd-tex. In addition to repeating the previously reported studies on Gd-tex in HT-29 cells, we tested five other human tumor cell lines (U-87 MG, U251-NCI, SW480, A549, and MCF-7). These studies included a Gd-tex treatment period of 24 h before irradiation (as in the original publication), with concentrations of Gd-tex ranging from 20-500 microM. In neither the HT-29 cells nor any of the other five human cell lines did we see radiation sensitization by Gd-tex. Two cell lines (MCF-7 and U-87 MG) were further tested for radiosensitization by Gd-tex under hypoxic conditions. No radiosensitization was observed in either case. Finally, the radiation response of two tumor lines were assessed in vivo. Neither HT-29 xenografts in severe combined immunodeficient (SCID) mice nor RIF-1 tumors growing in C3H mice demonstrated radiosensitization after Gd-tex treatment before single or fractionated doses of radiation. Our results raise questions about the efficacy of Gd-tex as a radiosensitizing agent. PMID:10646858

  13. Paris Saponins enhance radiosensitivity in a gefitinib‑resistant lung adenocarcinoma cell line by inducing apoptosis and G2/M cell cycle phase arrest.

    PubMed

    Zhao, Peng-Jun; Song, Shui-Chuan; Du, Lei-Wen; Zhou, Guo-Hua; Ma, Sheng-Lin; Li, Jin-Hui; Feng, Jian-Guo; Zhu, Xin-Hai; Jiang, Hao

    2016-03-01

    Acquired resistance to epidermal growth factor inhibitors has been reported to be associated with cross‑resistance to radiation. Paris Saponins (PSs) exert a wide range of pharmacological activities, including cell apoptosis induction, multidrug resistance inhibition, angiogenesis inhibition and tumor cell migration by modulating various signaling pathways. The present study aimed to investigate the radiosensitization effects of PSII, PSVI and PSVII in a gefitinib‑resistant PC‑9‑ZD lung adenocarcinoma cell line, and the possible mechanism underlying their function. A clonogenic assay was performed to determine the effects of PS radiosensitization on the PC‑9‑ZD cell line. The cell cycle was analyzed by flow cytometry, and cell apoptosis was analyzed with Annexin V/propidium iodide and Hoechst staining. Protein expression levels were detected by western blotting. The results of the present study revealed a significant increase in PC‑9‑ZD cell line radiosensitivity following treatment with PSs. PSs induced G2/M cell cycle phase arrest and apoptosis of the irradiated PC‑9‑ZD cells. Notably, the expression levels of B cell lymphoma 2 (Bcl‑2) were downregulated, and those of caspase‑3, Bcl‑2‑associated X protein (Bax) and p21/Waf1/Cip1 were upregulated following treatment with PSs. The present results demonstrated that PSs induced radiosensitivity in gefitinib‑resistant cells by inducing G2/M phase arrest and by enhancing the apoptotic response via the modulation of caspase‑3, Bax, Bcl‑2 and p21/Waf1/Cip1 expression. PMID:26846193

  14. High-mobility group boxes mediate cell proliferation and radiosensitivity via retinoblastoma-interaction-dependent and -independent mechanisms.

    PubMed

    Wang, Li-Li; Meng, Qing-Hui; Jiao, Yang; Xu, Jia-Ying; Ge, Chun-Min; Zhou, Ju-Ying; Rosen, Eliot M; Wang, Hai-Chao; Fan, Sai-Jun

    2012-06-01

    Our previous studies have shown that high-mobility group box 1 (HMGB1) could physically associate with the retinoblastoma (RB) protein via an LXCXE (leucine-X-cysteine-X-glutamic; X=any amino acid) motif. An identical LXCXE motif is present in the HMGB1-3 protein sequences, whereas a near-consensus LXCXD (leucine-X-cysteine-X-asparagine; X=any amino acid) motif is found in the HMGB4 protein. In this study, we have demonstrated that like HMGB1, HMGB2-3 also associated with the RB in vitro and in vivo, as evidenced by glutathione-s-transferase capture and immunoprecipitation-Western blot assays. A point mutation of the LXCXE or LXCXD motif led to disruption of RB:HMGB1-4 interactions. Enforced expression of HMGB1-3 or HMGB4 by adenoviral-vector-mediated gene transfer resulted in significant inhibition of breast cancer cell proliferation through an LXCXE- or LXCXD-dependent mechanism and an increased radiosensitivity through an LXCXE- or LXCXD-independent mechanism. These results suggest an important role of the LXCXE/D motif in RB:HMGB1-4 association and modulation of cancer cell growth, but not radiosensitivity. PMID:22655796

  15. β-elemene enhances both radiosensitivity and chemosensitivity of glioblastoma cells through the inhibition of the ATM signaling pathway.

    PubMed

    Liu, Siwei; Zhou, Lei; Zhao, Yongshun; Yuan, Yuhui

    2015-08-01

    Glioblastoma multiforme (GBM), a tumor associated with poor prognosis, is known to be resistant to radiotherapy and alkylating agents such as temozolomide (TMZ). β-elemene, a monomer found in Chinese traditional herbs extracted from Curcuma wenyujin, is currently being used as an antitumor drug for different types of tumors including GBM. In the present study, we investigated the roles of β-elemene in the radiosensitivity and chemosensitivity of GBM cells. Human GBM cell lines U87-MG, T98G, U251, LN229 and rat C6 cells were treated with β-elemene combined with radiation or TMZ. We used MTT and colony forming assays to evaluate the proliferation and survival of the cells, and the comet assay to observe DNA damage. Expression of proteins was analyzed by immunoblotting. In the present study, we found that β-elemene inhibited the proliferation and survival of different GBM cell lines when combined with radiotherapy or TMZ via inhibition of DNA damage repair. Treatment of GBM cells with β-elemene decreased the phosphorylation of ataxia telangiectasia mutated (ATM), AKT and ERK following radiotherapy or chemotherapy. These results revealed that β-elemene could significantly increase the radiosensitivity and chemosensitivity of GBM. β-elemene may be used as a potential drug in combination with the radiotherapy and chemotherapy of GBM. PMID:26062577

  16. Ectopically hTERT expressing adult human mesenchymal stem cells are less radiosensitive than their telomerase negative counterpart

    SciTech Connect

    Serakinci, Nedime . E-mail: nserakinci@health.sdu.dk; Christensen, Rikke; Graakjaer, Jesper; Cairney, Claire J.; Keith, W. Nicol; Alsner, Jan; Saretzki, Gabriele; Kolvraa, Steen

    2007-03-10

    During the past several years increasing evidence indicating that the proliferation capacity of mammalian cells is highly radiosensitive, regardless of the species and the tissue of origin of the cells, has accumulated. It has also been shown that normal bone marrow cells of mice have a similar radiosensitivity to other mammalian cells so far tested. In this study, we investigated the genetic effects of ionizing radiation (2.5-15 Gy) on normal human mesenchymal stem cells and their telomerised counterpart hMSC-telo1. We evaluated overall genomic integrity, DNA damage/repair by applying a fluorescence-detected alkaline DNA unwinding assay together with Western blot analyses for phosphorylated H2AX and Q-FISH was applied for investigation of telomeric damage. Our results indicate that hMSC and TERT-immortalized hMSCs can cope with relatively high doses of {gamma}-rays and that overall DNA repair is similar in the two cell lines. The telomeres were extensively destroyed after irradiation in both cell types suggesting that telomere caps are especially sensitive to radiation. The TERT-immortalized hMSCs showed higher stability at telomeric regions than primary hMSCs indicating that cells with long telomeres and high telomerase activity have the advantage of re-establishing the telomeric caps.

  17. 5-Iodo-2-deoxyuridine administered into the lateral cerebral ventricle as a radiosensitizer in the treatment of disseminated glioma

    SciTech Connect

    Deutsch, M.; Rewers, A.B.; Redgate, E.S.; Fisher, E.R.; Boggs, S.S. )

    1989-09-06

    A rat brain tumor model (Fischer 344 rats) with the clinical and pathological features of dissemination via the cerebrospinal fluid (CSF) pathways was used to demonstrate the efficacy of 5-iodo-2-deoxyuridine (IUDR) as a radiosensitizer when it is administered directly into the CSF. Stereotaxic implantation of 9L gliosarcoma cells (5 X 10(5)) into the CSF of the lateral cerebral ventricle resulted in widespread dissemination and median survival of 18.5 and 20 days (range, 10-22) in two experiments. A continuous 7-day infusion of IUDR into the CSF starting on the day of tumor implantation did not provide any beneficial effect. Irradiation of the cranial spinal axis with 800 rad on days 4, 6, and 7 after implantation achieved an increase in survival time that was modest but statistically significant. However, the combination of IUDR infusion and radiotherapy resulted in marked improvement in survival time and a 10% cure rate (two of 20 rats). This is the first demonstration in vivo that IUDR administered into the CSF can be a potent radiosensitizer.

  18. Inhibition of human positive cofactor 4 radiosensitizes human esophageal squmaous cell carcinoma cells by suppressing XLF-mediated nonhomologous end joining

    PubMed Central

    Qian, D; Zhang, B; Zeng, X-L; Le Blanc, J M; Guo, Y-H; Xue, C; Jiang, C; Wang, H-H; Zhao, T-S; Meng, M-B; Zhao, L-J; Hao, J-H; Wang, P; Xie, D; Lu, B; Yuan, Z-Y

    2014-01-01

    Radiotherapy has the widest application to esophageal squamous cell carcinoma (ESCC) patients. Factors associated with DNA damage repair have been shown to function in cell radiosensitivity. Human positive cofactor 4 (PC4) has a role in nonhomologous end joining (NHEJ) and is involved in DNA damage repair. However, the clinical significance and biological role of PC4 in cancer progression and cancer cellular responses to chemoradiotherapy (CRT) remain largely unknown. The aim of the present study was to investigate the potential roles of PC4 in the radiosensitivity of ESCC. In this study, we showed that knockdown of PC4 substantially increased ESCC cell sensitivity to ionizing radiation (IR) both in vitro and in vivo and enhanced radiation-induced apoptosis and mitotic catastrophe (MC). Importantly, we demonstrated that silencing of PC4 suppressed NHEJ by downregulating the expression of XLF in ESCC cells, whereas reconstituting the expression of XLF protein in the PC4-knockdown ESCC cells restored NHEJ activity and radioresistance. Moreover, high expression of PC4 positively correlated with ESCC resistance to CRT and was an independent predictor for short disease-specific survival of ESCC patients in both of our cohorts. These findings suggest that PC4 protects ESCC cells from IR-induced death by enhancing the NHEJ-promoting activity of XLF and could be used as a novel radiosensitivity predictor and a promising therapeutic target for ESCCs. PMID:25321468

  19. Expression of human protection of telomere 1 correlates with telomere length and radiosensitivity in the human laryngeal cancer Hep-2 cell line

    PubMed Central

    LEI, HAN; FENG, DALI; ZHOU, FUXIANG; XU, HUI; TANG, TIAN; YU, HAIJUN; XIE, CONGHUA; ZHOU, YUNFENG

    2015-01-01

    The close association between telomere length and radiosensitivity has been established by several studies. There is also a hypothesis that telomere length may be regulated by human protection of telomere 1 (hPOT1) in human carcinoma cells. In the present study, the hPOT1 level between the radioresistant Hep-2R cells and the wild-type were compared, and the results showed that the hPOT1 gene was upregulated in the radioresistant Hep-2R cell lines compared with the wild-type. This suggested that the expression level of hPOT1 correlates with radiosensitivity. Additionally, an hPOT1-directed short hairpin (sh)RNA plasmid was constructed and transferred into the Hep-2R cells, which lead to telomere shortening, an increase in apoptosis and markedly decreased growth of the RNAi-Hep-2R cell line. These results demonstrate that hPOT1-directed shRNAs are associated with telomere length and radiosensitivity, and maybe a potent sensitizer for laryngeal cancer radiotherapy. PMID:26622642

  20. Repair of Radiation-Induced Damage in Escherichia coli II. Effect of rec and uvr Mutations on Radiosensitivity, and Repair of X-Ray-Induced Single-Strand Breaks in Deoxyribonucleic Acid1

    PubMed Central

    Kapp, Daniel S.; Smith, Kendric C.

    1970-01-01

    Strains of Escherichia coli K-12 mutant in the genes controlling excision repair (uvr) and genetic recombination (rec) have been studied with reference to their radiosensitivity and their ability to repair X-ray-induced single-strand breaks in deoxyribonucleic acid (DNA). Mutations in the rec genes appreciably increase the radiosensitivity of E. coli K-12, whereas uvr mutations produce little if any increase in radiosensitivity. For a given dose of X-rays, the yield of single-strand breaks has been shown by alkaline sucrose gradient studies to be largely independent of the presence of rec or uvr mutations. The rec+ cells (including those carrying the uvrB5 mutation) could efficiently rejoin X-ray-induced single-strand breaks in DNA, whereas recA56 mutants could not repair these breaks to any great extent. The recB21 and recC22 mutants showed some indication of repair capacity. From these studies, it is concluded that a correlation exists between the inability to repair single-strand breaks and the radiosensitivity of the rec mutants of E. coli K-12. This suggests that unrepaired single-strand breaks may be lethal lesions in E. coli. PMID:4912530

  1. Effects of some hypoxic cell radiosensitizers on the decay of potentially lethal oxygen-dependent damage in fully hydrated spores.

    PubMed Central

    Tallentire, A.; Stratford, I. J.; Maughan, R. L.; Michael, B. D.

    1978-01-01

    Using a stopped-flow mixing and pulsed irradiation apparatus, a study has been made of the decay, to a harmless form, of radiation-induced species that would otherwise be lethal to spores on contact with oxygen. Aqueous suspensions of Bacillus megaterium spores were irradiated with electrons for approximately 1 s; at various times after irradiation oxygen in solution was added. As the interval between anoxic irradiation and introduction of oxygen increased, the fraction of spores surviving increased. This change in survival reflects the decay of potentially lethal species. The presence of electron-affinic radiosensitizers during irradiation enhanced the decay rate of this damage, the greatest enhancement being seen with sensitizers of the highest electron affinity. In contrast, the nitroxyl-free radical sensitizer TAN fixed the radiation-induced damage so that no increase in survival, and hence no decay, was seen. PMID:98174

  2. Synthesis of PEGylated Ferrocene Nanoconjugates as the Radiosensitizer of Cancer Cells.

    PubMed

    Tian, Jian; Chen, Jie; Ge, Cuicui; Liu, Xu; He, Jinlin; Ni, Peihong; Pan, Yue

    2016-06-15

    Radiation is one of the most widely used methods for cancer diagnosis and therapy. Herein, we report a new type of radiation sensitizer (Fc-PEG) by a facile one-step reaction of conjugating the hydrophilic PEG chain with hydrophobic ferrocene molecule. The chemical composition and structure of Fc-PEG have been thoroughly characterized by FT-IR, NMR, GPC, and MALDI-TOF mass spectrometry. This Fc-PEG conjugate could self-assemble in aqueous solution into spherical aggregates, and it was found that the exposure to 4 Gy of X-ray radiation have little influence on the shape and size of these aggregates. After the chemical bonding with PEG chains, the uptake level of Fe element could be enhanced via the formation of aggregates. The live/dead, CCK-8, as well as apoptosis assays, indicated that the death of cancer cells can be obviously increased by X-ray radiation after the incubation of these Fc-based nanoconjugates, which might be served as the radiation sensitizer toward cancer cells. We suggest that this radiosensitizing effect comes from the enhancement of reactive oxygen specimen (ROS) level as denoted by both flow cytometric and fluorescence microscopic analysis. The enhanced radiation sensitivity of cancer cells is contributed by the synergic effect of Fe-induced radiation-sensitizing and the increased uptake of nanoconjugates after polymeric grafting. PMID:27120689

  3. Proteasome Inhibitors Block DNA Repair and Radiosensitize Non-Small Cell Lung Cancer

    PubMed Central

    Kushwaha, Deepa S.; Hsieh, Grace; Merzon, Dmitry; Rameseder, Jonathan; Chen, Clark C.; D’Andrea, Alan D.; Kozono, David

    2013-01-01

    Despite optimal radiation therapy (RT), chemotherapy and/or surgery, a majority of patients with locally advanced non-small cell lung cancer (NSCLC) fail treatment. To identify novel gene targets for improved tumor control, we performed whole genome RNAi screens to identify knockdowns that most reproducibly increase NSCLC cytotoxicity. These screens identified several proteasome subunits among top hits, including the topmost hit PSMA1, a component of the core 20 S proteasome. Radiation and proteasome inhibition showed synergistic effects. Proteasome inhibition resulted in an 80–90% decrease in homologous recombination (HR), a 50% decrease in expression of NF-κB-inducible HR genes BRCA1 and FANCD2, and a reduction of BRCA1, FANCD2 and RAD51 ionizing radiation-induced foci. IκBα RNAi knockdown rescued NSCLC radioresistance. Irradiation of mice with NCI-H460 xenografts after inducible PSMA1 shRNA knockdown markedly increased murine survival compared to either treatment alone. Proteasome inhibition is a promising strategy for NSCLC radiosensitization via inhibition of NF-κB-mediated expression of Fanconi Anemia/HR DNA repair genes. PMID:24040035

  4. c-MYC is a radiosensitive locus in human breast cells.

    PubMed

    Wade, M A; Sunter, N J; Fordham, S E; Long, A; Masic, D; Russell, L J; Harrison, C J; Rand, V; Elstob, C; Bown, N; Rowe, D; Lowe, C; Cuthbert, G; Bennett, S; Crosier, S; Bacon, C M; Onel, K; Scott, K; Scott, D; Travis, L B; May, F E B; Allan, J M

    2015-09-17

    Ionising radiation is a potent human carcinogen. Epidemiological studies have shown that adolescent and young women are at increased risk of developing breast cancer following exposure to ionising radiation compared with older women, and that risk is dose-dependent. Although it is well understood which individuals are at risk of radiation-induced breast carcinogenesis, the molecular genetic mechanisms that underlie cell transformation are less clear. To identify genetic alterations potentially responsible for driving radiogenic breast transformation, we exposed the human breast epithelial cell line MCF-10A to fractionated doses of X-rays and examined the copy number and cytogenetic alterations. We identified numerous alterations of c-MYC that included high-level focal amplification associated with increased protein expression. c-MYC amplification was also observed in primary human mammary epithelial cells following exposure to radiation. We also demonstrate that the frequency and magnitude of c-MYC amplification and c-MYC protein expression is significantly higher in breast cancer with antecedent radiation exposure compared with breast cancer without a radiation aetiology. Our data also demonstrate extensive intratumor heterogeneity with respect to c-MYC copy number in radiogenic breast cancer, suggesting continuous evolution at this locus during disease development and progression. Taken together, these data identify c-MYC as a radiosensitive locus, implicating this oncogenic transcription factor in the aetiology of radiogenic breast cancer. PMID:25531321

  5. Ataxia-ocular motor apraxia syndrome: an investigation of cellular radiosensitivity of patients and their families.

    PubMed Central

    Hannan, M A; Sigut, D; Waghray, M; Gascon, G G

    1994-01-01

    Although ataxia-ocular motor apraxia (AOA) has been described as a disease entity mimicking ataxia telangiectasia (AT), no radiobiological studies have been carried out on cells from patients with AOA to find their possible relationship to AT. In the present study, cultured fibroblasts from three patients with AOA and their asymptomatic relatives (parents and sibs) were, therefore, compared with those from a classical AT homozygote, an AT heterozygote, and four healthy subjects for cell survival after acute and chronic irradiation. While a moderately increased cellular sensitivity (compared to normal) was observed in two AOA patients and most of their relatives, the degree of their radiosensitivity was quite different from that of the AT homozygote after both acute and chronic irradiation. One AOA patient exhibited increased cellular sensitivity similar to that of a classical AT homozygote up to 4% survival level after chronic irradiation but not after acute irradiation. A comparison of peripheral blood lymphocytes from two AOA patients, an AT homozygote, and two normal controls for spontaneous and (acute) radiation induced chromosomal breaks also failed to show any similarity between AOA and AT. These data support the notion that AOA is different from classical AT, and may represent a distinct disease entity controlled by specific gene(s), or compound heterozygotes involving different AT genes promoting the manifestation of AOA characteristics. PMID:7891378

  6. Autophagy inhibition radiosensitizes in vitro, yet reduces radioresponses in vivo due to deficient immunogenic signalling.

    PubMed

    Ko, A; Kanehisa, A; Martins, I; Senovilla, L; Chargari, C; Dugue, D; Mariño, G; Kepp, O; Michaud, M; Perfettini, J-L; Kroemer, G; Deutsch, E

    2014-01-01

    Clinical oncology heavily relies on the use of radiotherapy, which often leads to merely transient responses that are followed by local or distant relapse. The molecular mechanisms explaining radioresistance are largely elusive. Here, we identified a dual role of autophagy in the response of cancer cells to ionizing radiation. On one hand, we observed that the depletion of essential autophagy-relevant gene products, such as ATG5 and Beclin 1, increased the sensitivity of human or mouse cancer cell lines to irradiation, both in vitro (where autophagy inhibition increased radiation-induced cell death and decreased clonogenic survival) and in vivo, after transplantation of the cell lines into immunodeficient mice (where autophagy inhibition potentiated the tumour growth-inhibitory effect of radiotherapy). On the other hand, when tumour proficient or deficient for autophagy were implanted in immunocompetent mice, it turned out that defective autophagy reduced the efficacy of radiotherapy. Indeed, radiotherapy elicited an anti-cancer immune response that was dependent on autophagy-induced ATP release from stressed or dying tumour cells and was characterized by dense lymphocyte infiltration of the tumour bed. Intratumoural injection of an ecto-ATPase inhibitor restored the immune infiltration of autophagy-deficient tumours post radiotherapy and improved the growth-inhibitory effect of ionizing irradiation. Altogether, our results reveal that beyond its cytoprotective function, autophagy confers immunogenic properties to tumours, hence amplifying the efficacy of radiotherapy in an immunocompetent context. This has far-reaching implications for the development of pharmacological radiosensitizers. PMID:24037090

  7. c-MYC is a radiosensitive locus in human breast cells

    PubMed Central

    Wade, M A; Sunter, N J; Fordham, S E; Long, A; Masic, D; Russell, L J; Harrison, C J; Rand, V; Elstob, C; Bown, N; Rowe, D; Lowe, C; Cuthbert, G; Bennett, S; Crosier, S; Bacon, C M; Onel, K; Scott, K; Scott, D; Travis, L B; May, F E B; Allan, J M

    2015-01-01

    Ionising radiation is a potent human carcinogen. Epidemiological studies have shown that adolescent and young women are at increased risk of developing breast cancer following exposure to ionising radiation compared with older women, and that risk is dose-dependent. Although it is well understood which individuals are at risk of radiation-induced breast carcinogenesis, the molecular genetic mechanisms that underlie cell transformation are less clear. To identify genetic alterations potentially responsible for driving radiogenic breast transformation, we exposed the human breast epithelial cell line MCF-10A to fractionated doses of X-rays and examined the copy number and cytogenetic alterations. We identified numerous alterations of c-MYC that included high-level focal amplification associated with increased protein expression. c-MYC amplification was also observed in primary human mammary epithelial cells following exposure to radiation. We also demonstrate that the frequency and magnitude of c-MYC amplification and c-MYC protein expression is significantly higher in breast cancer with antecedent radiation exposure compared with breast cancer without a radiation aetiology. Our data also demonstrate extensive intratumor heterogeneity with respect to c-MYC copy number in radiogenic breast cancer, suggesting continuous evolution at this locus during disease development and progression. Taken together, these data identify c-MYC as a radiosensitive locus, implicating this oncogenic transcription factor in the aetiology of radiogenic breast cancer. PMID:25531321

  8. Targeting the AKT pathway: Repositioning HIV protease inhibitors as radiosensitizers

    PubMed Central

    Goda, Jayant S.; Pachpor, Tejaswini; Basu, Trinanjan; Chopra, Supriya; Gota, Vikram

    2016-01-01

    Cellular resistance in tumour cells to different therapeutic approaches has been a limiting factor in the curative treatment of cancer. Resistance to therapeutic radiation is a common phenomenon which significantly reduces treatment options and impacts survival. One of the mechanisms of acquiring resistance to ionizing radiation is the overexpression or activation of various oncogenes like the EGFR (epidermal growth factor receptor), RAS (rat sarcoma) oncogene or loss of PTEN (phosphatase and tensin homologue) which in turn activates the phosphatidyl inositol 3-kinase/protein kinase B (PI3-K)/AKT pathway responsible for radiation resistance in various tumours. Blocking the pathway enhances the radiation response both in vitro and in vivo. Due to the differential activation of this pathway (constitutively activated in tumour cells and not in the normal host cells), it is an excellent candidate target for molecular targeted therapy to enhance radiation sensitivity. In this regard, HIV protease inhibitors (HPIs) known to interfere with PI3-K/AKT signaling in tumour cells, have been shown to sensitize various tumour cells to radiation both in vitro and in vivo. As a result, HPIs are now being investigated as possible radiosensitizers along with various chemotherapeutic drugs. This review describes the mechanisms by which PI3-K/AKT pathway causes radioresistance and the role of HIV protease inhibitors especially nelfinavir as a potential candidate drug to target the AKT pathway for overcoming radioresistance and its use in various clinical trials for different malignancies. PMID:27121513

  9. Deubiquitylating enzyme USP9x regulates radiosensitivity in glioblastoma cells by Mcl-1-dependent and -independent mechanisms

    PubMed Central

    Wolfsperger, F; Hogh-Binder, S A; Schittenhelm, J; Psaras, T; Ritter, V; Bornes, L; Huber, S M; Jendrossek, V; Rudner, J

    2016-01-01

    Glioblastoma is a very aggressive form of brain tumor with limited therapeutic options. Usually, glioblastoma is treated with ionizing radiation (IR) and chemotherapy after surgical removal. However, radiotherapy is frequently unsuccessful, among others owing to resistance mechanisms the tumor cells have developed. Antiapoptotic B-cell leukemia (Bcl)-2 family members can contribute to radioresistance by interfering with apoptosis induction in response to IR. Bcl-2 and the closely related Bcl-xL and Mcl-1 are often overexpressed in glioblastoma cells. In contrast to Bcl-2 and Bcl-xL, Mcl-1 is a short-lived protein whose stability is closely regulated by ubiquitylation-dependent proteasomal degradation. Although ubiquitin ligases facilitate degradation, the deubiquitylating enzyme ubiquitin-specific protease 9x (USP9x) interferes with degradation by removing polyubiquitin chains from Mcl-1, thereby stabilizing this protein. Thus, an inability to downregulate Mcl-1 by enhanced USP9x activity might contribute to radioresistance. Here we analyzed the impact of USP9x on Mcl-1 levels and radiosensitivity in glioblastoma cells. Correlating Mcl-1 and USP9x expressions were significantly higher in human glioblastoma than in astrocytoma. Downregulation of Mcl-1 correlated with apoptosis induction in established glioblastoma cell lines. Although Mcl-1 knockdown by siRNA increased apoptosis induction after irradiation in all glioblastoma cell lines, USP9x knockdown significantly improved radiation-induced apoptosis in one of four cell lines and slightly increased apoptosis in another cell line. In the latter two cell lines, USP9x knockdown also increased radiation-induced clonogenic death. The massive downregulation of Mcl-1 and apoptosis induction in A172 cells transfected with USP9x siRNA shows that the deubiquitinase regulates cell survival by regulating Mcl-1 levels. In contrast, USP9x regulated radiosensitivity in Ln229 cells without affecting Mcl-1 levels. We conclude

  10. Silencing of R-Spondin1 increases radiosensitivity of glioma cells

    PubMed Central

    Ma, Guoda; Cui, Lili; Li, You; Zhou, Haihong; Liang, Wandong; Zhao, Bin; Li, Keshen

    2015-01-01

    Although radiation therapy is the most effective postoperative adjuvant treatment, it does not substantially improve the long-term outcomes of glioma patients because of the characteristic radioresistance of glioma. We found that R-Spondin1 (Rspo1) expression was elevated in high-grade gliomas and was associated with worse overall survival and disease-free survival. Rspo1 expression was also associated with reduced survival rates in glioma patients after treatment with radiotherapy and temozolomide (RT-TMZ). Importantly, Rspo1 was dramatically upregulated after radiation treatment in patients with glioma. Rspo1 silencing by shRNA potentiated glioma cell death upon radiation treatment. In a xenograft nude mouse model, combining radiation and silencing of Rspo1 potentiated tumor growth inhibition. Thus, combining radiotherapy with silencing of Rspo1 is a potential therapeutic approach. PMID:25865226

  11. 53BP1 foci as a marker of tumor cell radiosensitivity.

    PubMed

    Markova, E; Vasilyev, S; Belyaev, I

    2015-01-01

    Predicting tumor radiosensitivity has yet to be routinely integrated into radiotherapy. We analyzed the possibility to assess radiosensitivity of tumor cells based on endogenous and radiation-induced 53BP1 foci which are molecular markers of DNA double strand breaks (DSB). In eleven tumor cell lines of different origin, radiosensitivity was assessed by surviving cell fraction following irradiation with 2 Gy (SF2). 53BP1 foci were measured at 4 and 12 h post-irradiation by confocal laser microscopy and dedicated software. The correlation of 53BP1 foci and their post-irradiation kinetics with SF2 was assessed using Spearman rank test. The SF2 correlated with both excess of radiation-induced 53BP1 foci per cell at 4 h after irradiation and decay in number of 53BP1 foci from 4 to 12 h post-irradiation. The fraction of cells with multiple endogenous 53BP1 foci also correlated with SF2 of tumor cells. We conclude that the radiosensitivity of tumor cells can be predicted by kinetics of formation and decay of 53BP1 foci after irradiation. For the first time we report that the fraction of cells with multiple endogenous 53BP1 foci can be used as a marker of tumor cell radiosensitivity. PMID:26278144

  12. Mitochondria-Targeted Analogues of Metformin Exhibit Enhanced Antiproliferative and Radiosensitizing Effects in Pancreatic Cancer Cells.

    PubMed

    Cheng, Gang; Zielonka, Jacek; Ouari, Olivier; Lopez, Marcos; McAllister, Donna; Boyle, Kathleen; Barrios, Christy S; Weber, James J; Johnson, Bryon D; Hardy, Micael; Dwinell, Michael B; Kalyanaraman, Balaraman

    2016-07-01

    Metformin (Met) is an approved antidiabetic drug currently being explored for repurposing in cancer treatment based on recent evidence of its apparent chemopreventive properties. Met is weakly cationic and targets the mitochondria to induce cytotoxic effects in tumor cells, albeit not very effectively. We hypothesized that increasing its mitochondria-targeting potential by attaching a positively charged lipophilic substituent would enhance the antitumor activity of Met. In pursuit of this question, we synthesized a set of mitochondria-targeted Met analogues (Mito-Mets) with varying alkyl chain lengths containing a triphenylphosphonium cation (TPP(+)). In particular, the analogue Mito-Met10, synthesized by attaching TPP(+) to Met via a 10-carbon aliphatic side chain, was nearly 1,000 times more efficacious than Met at inhibiting cell proliferation in pancreatic ductal adenocarcinoma (PDAC). Notably, in PDAC cells, Mito-Met10 potently inhibited mitochondrial complex I, stimulating superoxide and AMPK activation, but had no effect in nontransformed control cells. Moreover, Mito-Met10 potently triggered G1 cell-cycle phase arrest in PDAC cells, enhanced their radiosensitivity, and more potently abrogated PDAC growth in preclinical mouse models, compared with Met. Collectively, our findings show how improving the mitochondrial targeting of Met enhances its anticancer activities, including aggressive cancers like PDAC in great need of more effective therapeutic options. Cancer Res; 76(13); 3904-15. ©2016 AACR. PMID:27216187

  13. Evaluation of Severe Combined Immunodeficiency and Combined Immunodeficiency Pediatric Patients on the Basis of Cellular Radiosensitivity

    PubMed Central

    Lobachevsky, Pavel; Woodbine, Lisa; Hsiao, Kuang-Chih; Choo, Sharon; Fraser, Chris; Gray, Paul; Smith, Jai; Best, Nickala; Munforte, Laura; Korneeva, Elena; Martin, Roger F.; Jeggo, Penny A.; Martin, Olga A.

    2016-01-01

    Pediatric patients with severe or nonsevere combined immunodeficiency have increased susceptibility to severe, life-threatening infections and, without hematopoietic stem cell transplantation, may fail to thrive. A subset of these patients have the radiosensitive (RS) phenotype, which may necessitate conditioning before hematopoietic stem cell transplantation, and this conditioning includes radiomimetic drugs, which may significantly affect treatment response. To provide statistical criteria for classifying cellular response to ionizing radiation as the measure of functional RS screening, we analyzed the repair capacity and survival of ex vivo irradiated primary skin fibroblasts from five dysmorphic and/or developmentally delayed pediatric patients with severe combined immunodeficiency and combined immunodeficiency. We developed a mathematical framework for the analysis of γ histone 2A isoform X foci kinetics to quantitate DNA-repair capacity, thus establishing crucial criteria for identifying RS. The results, presented in a diagram showing each patient as a point in a 2D RS map, were in agreement with findings from the assessment of cellular RS by clonogenic survival and from the genetic analysis of factors involved in the nonhomologous end-joining repair pathway. We provide recommendations for incorporating into clinical practice the functional assays and genetic analysis used for establishing RS status before conditioning. This knowledge would enable the selection of the most appropriate treatment regimen, reducing the risk for severe therapy-related adverse effects. PMID:26151233

  14. S-phase–specific radiosensitization by gemcitabine for therapeutic carbon ion exposure in vitro

    PubMed Central

    Harrabi, Semi B.; Adeberg, Sebastian; Winter, Marcus; Haberer, Thomas; Debus, Jürgen; Weber, Klaus-Josef

    2016-01-01

    Densely ionizing charged particle irradiation offers physical as well as biological advantages compared with photon irradiation. Radiobiological data for the combination of such particle irradiation (i.e. therapeutic carbon ions) with commonly used chemotherapeutics are still limited. Recent in vitro results indicate a general prevalence of additive cytotoxic effects in combined treatments, but an extension of established multimodal treatment regimens with photons to the inclusion of particle therapy needs to evaluate possible peculiarities of using high linear energy transfer (LET) radiation. The present study investigates the effect of combined radiochemotherapy using gemcitabine and high-LET irradiation with therapeutic carbon ions. In particular, the earlier observation of S-phase specific radiosensitization with photon irradiation should be evaluated with carbon ions. In the absence of the drug gemcitabine, carbon ion irradiation produced the typical survival behavior seen with X-rays—increased relative biological efficiency, and depletion of the survival curve's shoulder. By means of serum deprivation and subsequent replenishment, ∼70% S-phase content of the cell population was achieved, and such preparations showed radioresistance in both treatment arms—,photon and carbon ion irradiation. Combined modality treatment with gemcitabine caused significant reduction of clonogenic survival especially for the S-phase cells. WIDR cells exhibited S-phase–specific radioresistance with high-LET irradiation, although this was less pronounced than for X-ray exposure. The combined treatment with therapeutic carbon ions and gemcitabine caused the resistance phenomenon to disappear phenotypically. PMID:26747201

  15. Betulinyl Sulfamates as Anticancer Agents and Radiosensitizers in Human Breast Cancer Cells

    PubMed Central

    Bache, Matthias; Münch, Christin; Güttler, Antje; Wichmann, Henri; Theuerkorn, Katharina; Emmerich, Daniel; Paschke, Reinhard; Vordermark, Dirk

    2015-01-01

    Betulinic acid (BA), a natural compound of birch bark, is cytotoxic for many tumors. Recently, a betulinyl sulfamate was described that inhibits carbonic anhydrases (CA), such as CAIX, an attractive target for tumor-selective therapy strategies in hypoxic cancer cells. Data on combined CAIX inhibition with radiotherapy are rare. In the human breast cancer cell lines MDA-MB231 and MCF7, the effects of BA and betulinyl sulfamates on cellular and radiobiological behavior under normoxia and hypoxia were evaluated. The two most effective betulinyl sulfamates CAI 1 and CAI 3 demonstrated a 1.8–2.8-fold higher cytotoxicity than BA under normoxia in breast cancer cells, with IC50 values between 11.1 and 18.1 µM. BA exhibits its strongest cytotoxicity with IC50 values of 8.2 and 16.4 µM under hypoxia. All three substances show a dose-dependent increase in apoptosis, inhibition of migration, and inhibition of hypoxia-induced gene expression. In combination with irradiation, betulinyl sulfamates act as radiosensitizers, with DMF10 values of 1.47 (CAI 1) and 1.75 (CAI 3) under hypoxia in MDA-MB231 cells. BA showed additive effects in combination with irradiation. Taken together; our results suggest that BA and betulinyl sulfamates seem to be attractive substances to combine with radiotherapy; particularly for hypoxic breast cancer. PMID:26540049

  16. Betulinyl Sulfamates as Anticancer Agents and Radiosensitizers in Human Breast Cancer Cells.

    PubMed

    Bache, Matthias; Münch, Christin; Güttler, Antje; Wichmann, Henri; Theuerkorn, Katharina; Emmerich, Daniel; Paschke, Reinhard; Vordermark, Dirk

    2015-01-01

    Betulinic acid (BA), a natural compound of birch bark, is cytotoxic for many tumors. Recently, a betulinyl sulfamate was described that inhibits carbonic anhydrases (CA), such as CAIX, an attractive target for tumor-selective therapy strategies in hypoxic cancer cells. Data on combined CAIX inhibition with radiotherapy are rare. In the human breast cancer cell lines MDA-MB231 and MCF7, the effects of BA and betulinyl sulfamates on cellular and radiobiological behavior under normoxia and hypoxia were evaluated. The two most effective betulinyl sulfamates CAI 1 and CAI 3 demonstrated a 1.8-2.8-fold higher cytotoxicity than BA under normoxia in breast cancer cells, with IC50 values between 11.1 and 18.1 µM. BA exhibits its strongest cytotoxicity with IC50 values of 8.2 and 16.4 µM under hypoxia. All three substances show a dose-dependent increase in apoptosis, inhibition of migration, and inhibition of hypoxia-induced gene expression. In combination with irradiation, betulinyl sulfamates act as radiosensitizers, with DMF10 values of 1.47 (CAI 1) and 1.75 (CAI 3) under hypoxia in MDA-MB231 cells. BA showed additive effects in combination with irradiation. Taken together; our results suggest that BA and betulinyl sulfamates seem to be attractive substances to combine with radiotherapy; particularly for hypoxic breast cancer. PMID:26540049

  17. Dysregulated in vitro hematopoiesis, radiosensitivity, proliferation, and osteoblastogenesis with marrow from SAMP6 mice.

    PubMed

    O'Sullivan, Regina P; Greenberger, Joel S; Goff, Julie; Cao, Shaonan; Kingston, Kiera A; Zhou, Shuanhu; Dixon, Tracy; Houghton, Frank D; Epperly, Michael W; Wang, Hong; Glowacki, Julie

    2012-06-01

    The senescence accelerated-prone mouse variant 6 (SAMP6) shows normal growth followed by rapid aging, development of osteopenia, and shortened lifespan, compared with control R1 mice. Because oxidative stress is a fundamental mechanism of tissue aging, we tested whether cellular parameters that are associated with oxidative stress are impaired with marrow from SAMP6 mice. We compared in vitro hematopoiesis, irradiation sensitivity, proliferative potential, and osteoblastogenesis with marrow cells from SAMP6 and R1 mice. Marrow cells from SAMP6 mice showed shortened in vitro hematopoiesis; their stromal cells showed greater radiation sensitivity and decreased proliferation. Consistent with those properties, there was constitutive upregulation of transforming growth factor-β(1), an inhibitor of hematopoiesis, and of cell cycle inhibitory genes, p16(INK4A) and p19(ARF). Paradoxically, there was constitutive expression of osteoblast genes in stromal cells from SAMP6 mice, but in vitro matrix mineralization was impaired. These studies and data included in other reports indicate that impaired proliferation of osteoblast progenitors in SAMP6 marrow may be a major factor contributing to accelerated loss of bone mass. In sum, marrow from SAMP6 mice had diminished capacity for long-term hematopoiesis, increased radiosensitivity, and reduced proliferative capacity. PMID:22326715

  18. Dysregulated in vitro Hematopoiesis, Radiosensitivity, Proliferation, and Osteoblastogenesis with Marrow from SAMP6 Mice

    PubMed Central

    O’Sullivan, Regina P.; Greenberger, Joel S.; Goff, Julie; Cao, Shaonan; Kingston, Kiera A.; Zhou, Shuanhu; Dixon, Tracy; Houghton, Frank D.; Epperly, Michael W.; Wang, Hong; Glowacki, Julie

    2012-01-01

    The Senescence Accelerated-Prone mouse variant 6 (SAMP6) shows normal growth followed by rapid aging, development of osteopenia, and shortened lifespan, compared with control R1 mice. Because oxidative stress is a fundamental mechanism of tissue aging, we tested whether cellular parameters that are associated with oxidative stress are impaired with marrow from SAMP6 mice. We compared in vitro hematopoiesis, irradiation sensitivity, proliferative potential, and osteoblastogenesis with marrow cells from SAMP6 and R1 mice. Marrow cells from SAMP6 mice showed shortened in vitro hematopoiesis; their stromal cells showed greater radiation sensitivity and decreased proliferation. Consistent with those properties, there was constitutive upregulation of TGF-β1, an inhibitor of hematopoiesis, and of cell cycle inhibitory genes, p16INK4A and p19ARF. Paradoxically, there was constitutive expression of osteoblast genes in stromal cells from SAMP6 mice, but in vitro matrix mineralization was impaired. These studies and data included in other reports indicate that impaired proliferation of osteoblast progenitors in SAMP6 marrow may be a major factor contributing to accelerated loss of bone mass. In sum, marrow from SAMP6 mice had diminished capacity for long-term hematopoiesis, increased radiosensitivity, and reduced proliferative capacity. PMID:22326715

  19. Acid ceramidase upregulation in prostate cancer cells confers resistance to radiation: AC inhibition, a potential radiosensitizer.

    PubMed

    Mahdy, Ayman E M; Cheng, Joseph C; Li, Jun; Elojeimy, Saeed; Meacham, William D; Turner, Lorianne S; Bai, Aiping; Gault, Christopher R; McPherson, Alex S; Garcia, Nicole; Beckham, Thomas H; Saad, Antonio; Bielawska, Alicja; Bielawski, Jacek; Hannun, Yusuf A; Keane, Thomas E; Taha, Mohhammed I; Hammouda, Hisham M; Norris, James S; Liu, Xiang

    2009-03-01

    Radiation resistance in a subset of prostate tumors remains a challenge to prostate cancer radiotherapy. The current study on the effects of radiation on prostate cancer cells reveals that radiation programs an unpredicted resistance mechanism by upregulating acid ceramidase (AC). Irradiated cells demonstrated limited changes of ceramide levels while elevating levels of sphingosine and sphingosine-1-phosphate. By genetically downregulating AC with small interfering RNA (siRNA), we observed radiosensitization of cells using clonogenic and cytotoxicity assays. Conversely, AC overexpression further decreased sensitivity to radiation. We also observed that radiation-induced AC upregulation was sufficient to create cross-resistance to chemotherapy as demonstrated by decreased sensitivity to Taxol and C(6) ceramide compared to controls. Lower levels of caspase 3/7 activity were detected in cells pretreated with radiation, also indicating increased resistance. Finally, utilization of the small molecule AC inhibitor, LCL385, sensitized PPC-1 cells to radiation and significantly decreased tumor xenograft growth. These data suggest a new mechanism of cancer cell resistance to radiation, through upregulation of AC that is, in part, mediated by application of the therapy itself. An improved understanding of radiotherapy and the application of combination therapy achieved in this study offer new opportunities for the modulation of radiation effects in the treatment of cancer. PMID:19107118

  20. Evaluation of Severe Combined Immunodeficiency and Combined Immunodeficiency Pediatric Patients on the Basis of Cellular Radiosensitivity.

    PubMed

    Lobachevsky, Pavel; Woodbine, Lisa; Hsiao, Kuang-Chih; Choo, Sharon; Fraser, Chris; Gray, Paul; Smith, Jai; Best, Nickala; Munforte, Laura; Korneeva, Elena; Martin, Roger F; Jeggo, Penny A; Martin, Olga A

    2015-09-01

    Pediatric patients with severe or nonsevere combined immunodeficiency have increased susceptibility to severe, life-threatening infections and, without hematopoietic stem cell transplantation, may fail to thrive. A subset of these patients have the radiosensitive (RS) phenotype, which may necessitate conditioning before hematopoietic stem cell transplantation, and this conditioning includes radiomimetic drugs, which may significantly affect treatment response. To provide statistical criteria for classifying cellular response to ionizing radiation as the measure of functional RS screening, we analyzed the repair capacity and survival of ex vivo irradiated primary skin fibroblasts from five dysmorphic and/or developmentally delayed pediatric patients with severe combined immunodeficiency and combined immunodeficiency. We developed a mathematical framework for the analysis of γ histone 2A isoform X foci kinetics to quantitate DNA-repair capacity, thus establishing crucial criteria for identifying RS. The results, presented in a diagram showing each patient as a point in a 2D RS map, were in agreement with findings from the assessment of cellular RS by clonogenic survival and from the genetic analysis of factors involved in the nonhomologous end-joining repair pathway. We provide recommendations for incorporating into clinical practice the functional assays and genetic analysis used for establishing RS status before conditioning. This knowledge would enable the selection of the most appropriate treatment regimen, reducing the risk for severe therapy-related adverse effects. PMID:26151233

  1. Radiation-induced damage to normal tissues after radiotherapy in patients treated for gynecologic tumors: Association with single nucleotide polymorphisms in XRCC1, XRCC3, and OGG1 genes and in vitro chromosomal radiosensitivity in lymphocytes

    SciTech Connect

    Ruyck, Kim de . E-mail: kim.deruyck@UGent.be; Eijkeren, Marc van; Claes, Kathleen; Morthier, Rudy; Paepe, Anne de; Vral, Anne; Ridder, Leo de; Thierens, Hubert

    2005-07-15

    Purpose: To examine the association of polymorphisms in XRCC1 (194Arg/Trp, 280Arg/His, 399Arg/Gln, 632Gln/Gln), XRCC3 (5' UTR 4.541A>G, IVS5-14 17.893A>G, 241Thr/Met), and OGG1 (326Ser/Cys) with the development of late radiotherapy (RT) reactions and to assess the correlation between in vitro chromosomal radiosensitivity and clinical radiosensitivity. Methods and Materials: Sixty-two women with cervical or endometrial cancer treated with RT were included in the study. According to the Common Terminology Criteria for Adverse Events, version 3.0, scale, 22 patients showed late adverse RT reactions. Polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) assays were performed to examine polymorphic sites, the G2 assay was used to measure chromosomal radiosensitivity, and patient groups were compared using actuarial methods. Results: The XRCC3 IVS5-14 polymorphic allele was significantly associated with the risk of developing late RT reactions (odds ratio 3.98, p = 0.025), and the XRCC1 codon 194 variant showed a significant protective effect (p = 0.028). Patients with three or more risk alleles in XRCC1 and XRCC3 had a significantly increased risk of developing normal tissue reactions (odds ratio 10.10, p = 0.001). The mean number of chromatid breaks per cell was significantly greater in patients with normal tissue reactions than in patients with no reactions (1.16 and 1.34, respectively; p = 0.002). Patients with high chromosomal radiosensitivity showed a 9.2-fold greater annual risk of complications than patients with intermediate chromosomal radiosensitivity. Combining the G2 analysis with the risk allele model allowed us to identify 23% of the patients with late normal tissue reactions, without false-positive results. Conclusion: The results of the present study showed that clinical radiosensitivity is associated with an enhanced G2 chromosomal radiosensitivity and is significantly associated with a combination of different polymorphisms in

  2. Radio-sensitization of human leukaemic MOLT-4 cells by DNA-dependent protein kinase inhibitor, NU7441.

    PubMed

    Tichy, Ales; Durisova, Kamila; Salovska, Barbora; Pejchal, Jaroslav; Zarybnicka, Lenka; Vavrova, Jirina; Dye, Natalie A; Sinkorova, Zuzana

    2014-03-01

    We studied the effect of pre-incubation with NU7441, a specific inhibitor of DNA-dependent protein kinase (DNA-PK), on molecular mechanisms triggered by ionizing radiation (IR). The experimental design involved four groups of human T-lymphocyte leukaemic MOLT-4 cells: control, NU7441-treated (1 μM), IR-treated (1 Gy), and combination of NU7441 and IR. We used flow cytometry for apoptosis assessment, Western blotting and ELISA for detection of proteins involved in DNA repair signalling and epifluorescence microscopy for detection of IR-induced phosphorylation of histone H2A.X. We did not observe any major changes in the amount of DNA-PK subunits Ku70/80 caused by the combination of NU7441 and radiation. Their combination led to an increased phosphorylation of H2A.X, a hallmark of DNA damage. However, it did not prevent up-regulation of neither p53 (and its phosphorylation at Ser 15 and 392) nor p21. We observed a decrease in the levels of anti-apoptotic Mcl-1, cdc25A phosphatase, cleavage of PARP and a significant increase in apoptosis in the group treated with combination. In conclusion, the combination of NU7441 with IR caused increased phosphorylation of H2A.X early after irradiation and subsequent induction of apoptosis. It was efficient in MOLT-4 cells in 10× lower concentration than the inhibitor NU7026. NU7441 proved as a potent radio-sensitizing agent, and it might provide a platform for development of new radio-sensitizers in radiotherapy. PMID:24100951

  3. Radiosensitivity of different tissues from carrot root at different phases of growth in culture

    SciTech Connect

    Degani, N.; Pickholtz, D.

    1980-09-01

    The present work compares the effect of ..gamma..-radiation dose and time in culture on the growth of cambium and phloem carrot (Daucus carota) root explants. It was found that the phloem is more radiosensitive than the cambium and that both tissues were more radiosensitive when irradiated on excision at the G/sub 1/ phase rather than at the end of the lag phase on the ninth day of growth in culture when cells were predominantly at the G/sub 2/ phase. The nuclear volumes of cells from both tissues were similar but were larger at the end of the more radioresistant lag phase than those of the G/sub 1/ phase on excision. However, nuclear volume could not account for the differences in radiosensitivity between either the tissues or irradiation times in culture.

  4. MiR-122 Induces Radiosensitization in Non-Small Cell Lung Cancer Cell Line

    PubMed Central

    Ma, Debin; Jia, Hui; Qin, Mengmeng; Dai, Wenjie; Wang, Tao; Liang, Erguang; Dong, Guofu; Wang, Zuojun; Zhang, Zhiyuan; Feng, Fan

    2015-01-01

    MiR-122 is a novel tumor suppresser and its expression induces cell cycle arrest, or apoptosis, and inhibits cell proliferation in multiple cancer cells, including non-small cell lung cancer (NSCLC) cells. Radioresistance of cancer cell leads to the major drawback of radiotherapy for NSCLC and the induction of radiosensitization could be a useful strategy to fix this problem. The present work investigates the function of miR-122 in inducing radiosensitization in A549 cell, a type of NSCLC cells. MiR-122 induces the radiosensitization of A549 cells. MiR-122 also boosts the inhibitory activity of ionizing radiation (IR) on cancer cell anchor-independent growth and invasion. Moreover, miR-122 reduced the expression of its targeted genes related to tumor-survival or cellular stress response. These results indicate that miR-122 would be a novel strategy for NSCLC radiation-therapy. PMID:26389880

  5. MiR-122 Induces Radiosensitization in Non-Small Cell Lung Cancer Cell Line.

    PubMed

    Ma, Debin; Jia, Hui; Qin, Mengmeng; Dai, Wenjie; Wang, Tao; Liang, Erguang; Dong, Guofu; Wang, Zuojun; Zhang, Zhiyuan; Feng, Fan

    2015-01-01

    MiR-122 is a novel tumor suppresser and its expression induces cell cycle arrest, or apoptosis, and inhibits cell proliferation in multiple cancer cells, including non-small cell lung cancer (NSCLC) cells. Radioresistance of cancer cell leads to the major drawback of radiotherapy for NSCLC and the induction of radiosensitization could be a useful strategy to fix this problem. The present work investigates the function of miR-122 in inducing radiosensitization in A549 cell, a type of NSCLC cells. MiR-122 induces the radiosensitization of A549 cells. MiR-122 also boosts the inhibitory activity of ionizing radiation (IR) on cancer cell anchor-independent growth and invasion. Moreover, miR-122 reduced the expression of its targeted genes related to tumor-survival or cellular stress response. These results indicate that miR-122 would be a novel strategy for NSCLC radiation-therapy. PMID:26389880

  6. Hypoxic radiosensitizers: prospects for effective compounds with fewer toxic side-effects.

    PubMed Central

    Rupp, W. D.; Mroczkowski, Z.; Agrawal, K. C.

    1978-01-01

    Several radiosensitizing chemicals, including a family of simple nitroimidazoles, were examined in E. coli and compared with misonidazole for toxic side-effects on endpoints such as mutagenesis, cell killing and inhibition of the synthesis of the inducible enzyme beta-galactosidase. While all the compounds were similar to misonidazole or better in radiosensitization, marked differences in the various side effects were found. There results show that for E. coli it is possible to find compounds that sensitize as well as misonidazole but which have decreased mutagenicity and fewer other side-effects. Of the compounds examined, KA121 (2,5-dinitroimidazole) is the most promising for future study because it combines good radiosensitization with low mutagenicity and toxicity. PMID:98175

  7. Association between cellular radiosensitivity and G1/G2 checkpoint proficiencies in human cholangiocarcinoma cell lines.

    PubMed

    Hematulin, Arunee; Sagan, Daniel; Sawanyawisuth, Kanlayanee; Seubwai, Wunchana; Wongkham, Sopit

    2014-09-01

    Cholangiocarcinoma is a destructive malignancy with a poor prognosis and lack of effective medical treatment. Radiotherapy is an alternative treatment for patients with unresectable cholangiocarcinoma. However, there are limited data on the radiation responsiveness of individual cholangiocarcinoma cells, which is a key factor that influences radiation treatment outcome. In this study, we found that cholangiocarcinoma cell lines differ remarkably in their radiosensitivity. The variation of radiosensitivity of cholangiocarcinoma cells correlates with their p53 status and existing G1 and/or G2 checkpoint defects. We also demonstrated the potential of checkpoint kinase Chk1/2 inhibition on the enhancement of the radiosensitivity of cholangiocarcinoma cells. Thus, this study provides useful information for predicting radiation response and provides evidence for the enchantment of radiotherapeutic efficiency by targeting checkpoint kinase Chk1/2 in some subpopulations of cholangiocarcinoma patients. PMID:24969815

  8. Nanoscale Dynamics of Radiosensitivity: Role of Low Energy Electrons

    NASA Astrophysics Data System (ADS)

    Sanche, Léon

    This chapter addresses the nanoscale dynamics involved in the sensitization of biological cells to ionizing radiation. More specifically, it describes the role of low energy electrons (LEE) in radiosensitization by gold nanoparticles and chemotherapeutic agents, as well as potential applications to radiotherapy. The basic mechanisms of action of the LEE generated within nanoscopic volumes by ionizing radiation are described in solid water ice and various forms of DNA. These latter include the subunits (i.e., a base, a sugar or the phosphate group), short single strands (i.e., oligonucleotides) and plasmid and linear DNA. By comparing the results from experiments with the different forms of the DNA molecule and theory, it is possible to determine fundamental mechanisms that are involved in the dissociation of the subunits, base release and the production of single, double-strand breaks and cross-links. Below 15 eV, LEE localize on DNA subunits to form transient negative ions. Such states can damage DNA by dissociating into a stable anion and radical fragment(s), via dissociative electron attachment, or by decaying into dissociative electronically excited states. LEE can also transfer from one DNA subunit to another, particularly from a base to the phosphate group, where they can induce cleavage of the C-O bond (i.e., break a strand). DNA damage and the corresponding nanoscale dynamics are found to be modified in the presence of other cellular constituents. For example, condensing on DNA the most abundant cellular molecule, H2O, induces the formation of a new type of transient anion whose parent is a H2O-DNA complex.

  9. Intra-arterial bromodeoxyuridine radiosensitization of malignant gliomas

    SciTech Connect

    Hegarty, T.J.; Thornton, A.F.; Diaz, R.F.; Chandler, W.F.; Ensminger, W.D.; Junck, L.; Page, M.A.; Gebarski, S.S.; Hood, T.W.; Stetson, P.L. )

    1990-08-01

    In the 1950's it was first observed that mammalian cells exposed to the halogenated deoxyuridines were more sensitive to ultraviolet light and radiation than untreated cells. This prompted early clinical trials with bromodeoxyuridine (BUdR) which showed mixed results. More recently, several Phase I studies, while establishing the feasibility of continuous intravenous (IV) infusion of BUdR, have reported significant dose limiting skin and bone marrow toxicities and have questioned the optimal method of BUdR delivery. To exploit the high mitotic activity of malignant gliomas relative to surrounding normal brain tissue, we have developed a permanently implantable infusion pump system for safe, continuous intraarterial (IA) internal carotid BUdR delivery. Since July 1985, 23 patients with malignant brain tumors (18 grade 4, 5 grade 3) have been treated in a Phase I clinical trial using IA BUdR (400-600 mg/m2/day X 8 1/2 weeks) and focal external beam radiotherapy (59.4 Gy at 1.8 Gy/day in 6 1/2 weeks). Following initial biopsy/surgery the infusion pump system was implanted; BUdR infusion began 2 weeks prior to and continued throughout the 6 1/2 week course of radiotherapy. There have been no vascular complications. Side-effects in all patients have included varying degrees of anorexia, fatigue, ipsilateral forehead dermatitis, blepharitis, and conjunctivitis. Myelosuppression requiring dose reduction occurred in one patient. An overall Kaplan-Meier estimated median survival of 20 months has been achieved. As in larger controlled series, histologic grade and age are prognostically significant. We have shown in a Phase I study that IA BUdR radiosensitization is safe, tolerable, may lead to improved survival, and appears to be an efficacious primary treatment of malignant gliomas.

  10. Protein-directed modulation of high-LET hyperthermic radiosensitization

    SciTech Connect

    Chang, P.Y.

    1991-01-01

    A pair of Chinese Hamster Ovary cell lines, the wild-type CHO-SC1, and its temperature-sensitive mutant (CHO-tsH1) was used to examine the importance of protein synthesis in the development of thermotolerance. The classical biphasic thermotolerant survival response to hyperthermia was observed in the SC1 cells after continuous heating at 41.5C to 42.5C, while tsH1 showed no thermotolerance. In separate experiments, each cell line was triggered and challenged at 45C. The heat doses were separated with graded incubaton periods at 35C or 40C for thermotolerance development. SC1 cells expressed thermoresistance, with the synthesis of heat shock proteins, under both incubation conditions. tsH1 cells expressed thermotolerance similar to that seen in the SC1 cells when incubated at 35C, but the survival response with the non-permissive 40C incubation was much reduced in the absence of protein synthesis. The combined effects of heavy-ion radiation and hyperthermia were examined using the same cell system. A mild heat dose of 41.5C was used in conjunction with Neon particle radiation of various high LET values. The cell killing effects were highly dependent on the sequence of application of heat and Neon radiation. Heat applied immediately after Neon irradiation was more cytotoxic to SC1 cells than when heat was applied prior to the irradiation. The ability of cells to synthesize new proteins plays a key role in this sequence-dependent thermal radiosensitization. In the absence of protein synthesis in the tsH1 cells, the high-LET thermal enhancement for cell-killing was unchanged regardless of the sequence. In the presence of protein synthetic activity in the SC1 cells, the thermal enhancement of radiation-induced cell killing was LET-dependent.

  11. Enhanced radiosensitization of p53 mutant cells by oleamide

    SciTech Connect

    Lee, Yoon-Jin; Chung, Da Yeon; Lee, Su-Jae; Ja Jhon, Gil; Lee, Yun-Sil . E-mail: yslee@kcch.re.kr

    2006-04-01

    Purpose: Effect of oleamide, an endogenous fatty-acid primary amide, on tumor cells exposed to ionizing radiation (IR) has never before been explored. Methods and Materials: NCI H460, human lung cancer cells, and human astrocytoma cell lines, U87 and U251, were used. The cytotoxicity of oleamide alone or in combination with IR was determined by clonogenic survival assay, and induction of apoptosis was estimated by FACS analysis. Protein expressions were confirmed by Western blotting, and immunofluorescence analysis of Bax by use of confocal microscopy was also performed. The combined effect of IR and oleamide to suppress tumor growth was studied by use of xenografts in the thighs of nude mice. Results: Oleamide in combination with IR had a synergistic effect that decreased clonogenic survival of lung-carcinoma cell lines and also sensitized xenografts in nude mice. Enhanced induction of apoptosis of the cells by the combined treatment was mediated by loss of mitochondrial membrane potential, which resulted in the activation of caspase-8, caspase-9, and caspase-3 accompanied by cytochrome c release and Bid cleavage. The synergistic effects of the combined treatment were more enhanced in p53 mutant cells than in p53 wild-type cells. In p53 wild-type cells, both oleamide and radiation induced Bax translocation to mitochondria. On the other hand, in p53 mutant cells, radiation alone slightly induced Bax translocation to mitochondria, whereas oleamide induced a larger translocation. Conclusions: Oleamide may exhibit synergistic radiosensitization in p53 mutant cells through p53-independent Bax translocation to mitochondria.

  12. 5-Iodo-2-Pyrimidinone-2'-Deoxyribose-Mediated Cytotoxicity and Radiosensitization in U87 Human Glioblastoma Xenografts

    SciTech Connect

    Kinsella, Timothy J. Kinsella, Michael T.; Seo, Yuji; Berk, Gregory

    2007-11-15

    Purpose: 5-Iodo-2-pyrimidinone-2'-deoxyribose (IPdR) is a novel orally administered (p.o.) prodrug of 5-iododeoxyuridine. Because p.o. IPdR is being considered for clinical testing as a radiosensitizer in patients with high-grade gliomas, we performed this in vivo study of IPdR-mediated cytotoxicity and radiosensitization in a human glioblastoma xenograft model, U87. Methods and Materials: Groups of 8 or 9 athymic male nude mice (6-8 weeks old) were implanted with s.c. U87 xenograft tumors (4 x 10{sup 6} cells) and then randomized to 10 treatment groups receiving increasing doses of p.o. IPdR (0, 100, 250, 500, and 1000 mg/kg/d) administered once daily (q.d.) x 14 days with or without radiotherapy (RT) (0 or 2 Gy/d x 4 days) on days 11-14 of IPdR treatment. Systemic toxicity was determined by body weight measurements during and after IPdR treatment. Tumor response was assessed by changes in tumor volumes. Results: IPdR alone at doses of {>=}500 mg/kg/d resulted in moderate inhibition of tumor growth. The combination of IPdR plus RT resulted in a significant IPdR dose-dependent tumor growth delay, with the maximum radiosensitization using {>=}500 mg/kg/d. IPdR doses of 500 and 1000 mg/kg/d resulted in transient 5-15% body weight loss during treatment. Conclusions: In U87 human glioblastoma s.c. xenografts, p.o. IPdR given q.d. x 14 days and RT given 2 Gy/d x 4 days (days 11-14 of IPdR treatment) results in a significant tumor growth delay in an IPdR dose-dependent pattern. The use of p.o. IPdR plus RT holds promise for Phase I/II testing in patients with high-grade gliomas.

  13. The PCC assay can be used to predict radiosensitivity in biopsy cultures irradiated with different types of radiation.

    PubMed

    Suzuki, Masao; Tsuruoka, Chizuru; Nakano, Takashi; Ohno, Tatsuya; Furusawa, Yoshiya; Okayasu, Ryuichi

    2006-12-01

    The aim of this study was to identify potential biomarkers for radiosensitivity using the relationship between cell killing and the yield of excess chromatin fragments detected with the premature chromosome condensation (PCC) technique. This method was applied to primary cultured cells obtained from biopsies from patients. Six primary culture biopsies were obtained from 6 patients with carcinoma of the cervix before starting radiotherapy. The cultures were irradiated with two different LET carbon-ion beams (LET = 13 keV/microm, 77.1+/-2.8 keV/microm) and 200 kV X-rays. The carbon-ion beams were produced by Heavy Ion Medical Accelerator in Chiba (HIMAC). PCC was performed using the polyethylene glycol-mediated cell fusion technique. The yield of excess chromatin fragments were measured by counting the number of unrejoined chromatin fragments detected with the PCC technique after a 24-h post-irradiation incubation period. Obtained results indicated that cultures which were more sensitive to killing were also more susceptible to the induction of excess chromatin fragments. Furthermore there was a good correlation between cell killing and excess chromatin fragments among the 6 cell cultures examined. There is also evidence that the induction of excess chromatin fragments increased with increasing LET as well as cell-killing effect in the same cell culture. The data reported here support the idea that the yield of excess chromatin fragments detected with the PCC technique might be useful for predicting the radiosensitivity of cells contained in tumor tissue, and to predict responses to different radiation types. PMID:17089052

  14. The pharmacokinetics in mice and dogs of nitroimidazole radiosensitizers and chemosensitizers more lipophilic than misonidazole

    SciTech Connect

    White, R.; Workman, P.; Owen, L.

    1982-03-01

    The pharmacokinetic properties of nitroimidazole radiosensitizers and chemosensitizers more lipophilic than misonidazole (MISO) were examined. In dogs, 2 analogues showed comparable peak plasma concentrations with considerable shorter half-lives (t1/2) and reduced areas under curves (AUC). Benznidazole (R0 07-1051) had a much longer t1/2, a higher AUC, and somewhat higher peak concentrations. In mice tumor/plasma, brain/plasma, and tumor/brain ratios were generally similar to MISO, as was penetration of brain and peripheral nerve by benznidazole in dogs. Selection of lipophilic analogues with appropriate pharmacokinetic properties may facilitate accommodation of the potentially different requirements for improved radiosensitization or chemosensitization.

  15. Differential radiosensitivity in cultured B-16 melanoma cells following interrupted melanogenesis induced by glucosamine

    SciTech Connect

    Mileo, A.M.; Mattei, E.; Fanuele, M.; Delpino, A.; Ferrini, U. )

    1989-05-01

    The relationship between cell pigmentation and radiosensitivity was investigated in a cell model in which melanogenesis was suppressed by a glycosylation inhibitor. It was found that X-irradiation of melanotic B-16 melanoma cells and their amelanotic counterparts, obtained by glucosamine treatment, showed an inverse correlation between radiosensitivity and melanin contents. Since melanogenesis interruption by glucosamine does not affect the DNA repair capacity of nonpigmented cells, it is likely that intracellular melanins play a role in the relative resistance of pigmented cells to X-irradiation.

  16. Sustained Radiosensitization of Hypoxic Glioma Cells after Oxygen Pretreatment in an Animal Model of Glioblastoma and In Vitro Models of Tumor Hypoxia

    PubMed Central

    Clarke, Ryon H.; Moosa, Shayan; Anzivino, Matthew; Wang, Yi; Floyd, Desiree Hunt; Purow, Benjamin W.; Lee, Kevin S.

    2014-01-01

    Glioblastoma multiforme (GBM) is the most common and lethal form of brain cancer and these tumors are highly resistant to chemo- and radiotherapy. Radioresistance is thought to result from a paucity of molecular oxygen in hypoxic tumor regions, resulting in reduced DNA damage and enhanced cellular defense mechanisms. Efforts to counteract tumor hypoxia during radiotherapy are limited by an attendant increase in the sensitivity of healthy brain tissue to radiation. However, the presence of heightened levels of molecular oxygen during radiotherapy, while conventionally deemed critical for adjuvant oxygen therapy to sensitize hypoxic tumor tissue, might not actually be necessary. We evaluated the concept that pre-treating tumor tissue by transiently elevating tissue oxygenation prior to radiation exposure could increase the efficacy of radiotherapy, even when radiotherapy is administered after the return of tumor tissue oxygen to hypoxic baseline levels. Using nude mice bearing intracranial U87-luciferase xenografts, and in vitro models of tumor hypoxia, the efficacy of oxygen pretreatment for producing radiosensitization was tested. Oxygen-induced radiosensitization of tumor tissue was observed in GBM xenografts, as seen by suppression of tumor growth and increased survival. Additionally, rodent and human glioma cells, and human glioma stem cells, exhibited prolonged enhanced vulnerability to radiation after oxygen pretreatment in vitro, even when radiation was delivered under hypoxic conditions. Over-expression of HIF-1α reduced this radiosensitization, indicating that this effect is mediated, in part, via a change in HIF-1-dependent mechanisms. Importantly, an identical duration of transient hyperoxic exposure does not sensitize normal human astrocytes to radiation in vitro. Taken together, these results indicate that briefly pre-treating tumors with elevated levels of oxygen prior to radiotherapy may represent a means for selectively targeting radiation

  17. Radiosensitization effect of folate-conjugated gold nanoparticles on HeLa cancer cells under orthovoltage superficial radiotherapy techniques

    NASA Astrophysics Data System (ADS)

    Khoshgard, Karim; Hashemi, Bijan; Arbabi, Azim; Javad Rasaee, Mohammad; Soleimani, Masoud

    2014-05-01

    Due to the high atomic number of gold nanoparticles (GNPs), they are known as new radiosensitizer agents for enhancing the efficiency of superficial radiotherapy techniques by increasing the dose absorbed in tumor cells wherein they can be accumulated selectively. The aim of this study was to compare the effect of various common low energy levels of orthovoltage x-rays and megavoltage γ-rays (Co-60) on enhancing the therapeutic efficiency of HeLa cancer cells in the presence of conjugated folate and non-conjugated (pegylated) GNPs. To achieve this, GNPs with an average diameter of 52 nm were synthesized and conjugated to folic acid molecules. Pegylated GNPs with an average diameter of 47 nm were also synthesized and used as non-conjugated folate GNPs. Cytotoxicity assay of the synthesized folate-conjugated and pegylated GNPs was performed using different levels of nanoparticle concentration incubated with HeLa cells for 24 h. The radiosensitizing effect of both the conjugated and pegylated GNPs on the cells at a concentration of 50 µM was compared using MTT as well as clonogenic assays after exposing them to 2 Gy ionizing radiation produced by an orthovoltage x-ray machine at four different kVps and γ-rays of a Co-60 unit. Significant differences were noted among various irradiated groups with and without the folate conjugation, with an average dose enhancement factor (DEF) of 1.64 ± 0.05 and 1.35 ± 0.05 for the folate-conjugated and pegylated GNPs, respectively. The maximum DEF was obtained with the 180 kVp x-ray beam for both of the GNPs. Folate-conjugated GNPs can significantly enhance the cell killing potential of orthovoltage x-ray energies (especially at 180 kVp) in folate receptor-expressing cancer cells, such as HeLa, in superficial radiotherapy techniques.

  18. Radiosensitization effect of folate-conjugated gold nanoparticles on HeLa cancer cells under orthovoltage superficial radiotherapy techniques.

    PubMed

    Khoshgard, Karim; Hashemi, Bijan; Arbabi, Azim; Rasaee, Mohammad Javad; Soleimani, Masoud

    2014-05-01

    Due to the high atomic number of gold nanoparticles (GNPs), they are known as new radiosensitizer agents for enhancing the efficiency of superficial radiotherapy techniques by increasing the dose absorbed in tumor cells wherein they can be accumulated selectively. The aim of this study was to compare the effect of various common low energy levels of orthovoltage x-rays and megavoltage γ-rays (Co-60) on enhancing the therapeutic efficiency of HeLa cancer cells in the presence of conjugated folate and non-conjugated (pegylated) GNPs. To achieve this, GNPs with an average diameter of 52 nm were synthesized and conjugated to folic acid molecules. Pegylated GNPs with an average diameter of 47 nm were also synthesized and used as non-conjugated folate GNPs. Cytotoxicity assay of the synthesized folate-conjugated and pegylated GNPs was performed using different levels of nanoparticle concentration incubated with HeLa cells for 24 h. The radiosensitizing effect of both the conjugated and pegylated GNPs on the cells at a concentration of 50 µM was compared using MTT as well as clonogenic assays after exposing them to 2 Gy ionizing radiation produced by an orthovoltage x-ray machine at four different kVps and γ-rays of a Co-60 unit. Significant differences were noted among various irradiated groups with and without the folate conjugation, with an average dose enhancement factor (DEF) of 1.64 ± 0.05 and 1.35 ± 0.05 for the folate-conjugated and pegylated GNPs, respectively. The maximum DEF was obtained with the 180 kVp x-ray beam for both of the GNPs. Folate-conjugated GNPs can significantly enhance the cell killing potential of orthovoltage x-ray energies (especially at 180 kVp) in folate receptor-expressing cancer cells, such as HeLa, in superficial radiotherapy techniques. PMID:24733041

  19. [Blood DNA Radiosensitivity May Be Predictive Marker for Efficacy of Radiation Therapy in Glioma Tumorbearing Individuals].

    PubMed

    Ivanov, S D; Korytova, L I; Yamshanov, V A; Zhabina, R M; Semenov, A L; Krasnikova, V G

    2015-01-01

    Animal and clinical studies were conducted to evaluate the association between the blood DNA radiosensitivity, assessed by determining the original S-index ex vivo, and the response of gliomas to irradiation in vivo. Possible modifications of the latter after administration of iron-containing water (ICW) in rats were also explored. The study was performed on the rats with subcutaneously implanted experimental glioma-35. The tumors were locally X-irradiated with a single 15 Gy dose as a radiation therapy (RT). ICW (60-63 mg · Fe 2+/l) was administered as a drinking water for 3 days before treatment. The animals underwent blood sampling for analysis of the DNA concentration and leukocyte count. The DNA index was estimated 24 h after RT. The S-index was evaluated within 4 h before RT. The mean initial S-index in the blood samples of glioma-bearing rats was 0.73 ± 0.05. Addition of ICW ex vivo resulted in a significantly increased S-index in a half of the samples. In general, the irradiated rats, which had been given pretreatment with ICW and demonstrated an ex vivo increase of the S-index to > 1.0, showed the most marked inhibition of tumor progression and the smallest tumor volume 25 days after irradiation. They also exhibited the lowest rate of growth and the longest survival. Determination of the biochemical S-index and evaluation of its changes ex vivo caused by ICW may be predictive of the response of experimental glioma to irradiation with radiomodification. The S-index may serve as a predictive indicator in clinic of the efficient evaluation of RT in patients with glioma. PMID:26863781

  20. Study Illuminates K-Ras4B Activation, Which May Help Predict Drug Resistance | Poster

    Cancer.gov

    Until recently, researchers studying RAS, a family of proteins involved in transmitting signals within cells, believed that the exchange of guanosine 5’-diphosphate (GDP) by guanosine triphosphate (GTP) was sufficient to activate the protein. Once activated, RAS can cause unintended and overactive signaling in cells, which can lead to cell division and, ultimately, cancer.

  1. Radiosensitization of head and neck squamous cell carcinoma by a SMAC-mimetic compound, SM-164, requires activation of caspases

    PubMed Central

    Yang, Jie; McEachern, Donna; Li, Wenyan; Davis, Mary A.; Li, Hua; Morgan, Meredith A.; Bai, Longchuan; Sebolt, Jonathan T.; Sun, Haiying; Lawrence, Theodore S.; Wang, Shaomeng; Sun, Yi

    2011-01-01

    Chemoradiation is the treatment of choice for locally advanced head and neck squamous cell carcinoma (HNSCC). However, radioresistance, which contributes to local recurrence, remains a significant therapeutic problem. In this study, we characterized SM-164, a small SMAC mimetic compound that promotes degradation of cIAP-1 (also known as BIRC2) and releases active caspases from XIAP inhibitory binding, as a radiosensitizing agent in HNSCC cells. We found that SM-164 at nanomolar concentrations induced radiosensitization in some HNSCC cell lines in a manner dependent on intrinsic sensitivity to caspase activation and apoptosis induction. Blockage of caspase activation via siRNA knockdown or a pan-caspase inhibitor, z-VAD-fmk largely abrogated SM-164 radiosensitization. On the other hand, the resistant lines with a high level of BCL-2 that blocks caspase activation and apoptosis induction became sensitive to radiation upon BCL-2 knockdown. Mechanistic studies revealed that SM-164 radiosensitization in sensitive cells was associated with NFκB activation and TNFα secretion, followed by activation of caspases-8 and -9, leading to enhanced apoptosis. Finally, SM-164 also radiosensitized human tumor xenograft, while causing minimal toxicity. Thus, SM-164 is a potent radiosensitizer via a mechanism involving caspase activation and holds promise for future clinical development as a novel class of radiosensitizer for the treatment of a subset of head and neck cancer patients. PMID:21282353

  2. Mitochondrial DNA and Functional Investigations into the Radiosensitivity of Four Mouse Strains

    PubMed Central

    Zhang, Steven B.; Maguire, David; Zhang, Mei; Tian, Yeping; Yang, Shanmin; Zhang, Amy; Casey-Sawicki, Katherine; Han, Deping; Ma, Jun; Yin, Liangjie; Guo, Yongson; Wang, Xiaohui; Chen, Chun; Litvinchuk, Alexandra; Zhang, Zhenhuan; Swarts, Steven; Vidyasagar, Sadasivan; Zhang, Lurong; Okunieff, Paul

    2014-01-01

    We investigated whether genetic radiosensitivity-related changes in mtDNA/nDNA ratios are significant to mitochondrial function and if a material effect on mtDNA content and function exists. BALB/c (radiosensitive), C57BL/6 (radioresistant), and F1 hybrid mouse strains were exposed to total body irradiation. Hepatic genomic DNA was extracted, and mitochondria were isolated. Mitochondrial oxygen consumption, ROS, and calcium-induced mitochondrial swelling were measured. Radiation influenced strain-specific survival in vivo. F1 hybrid survival was influenced by maternal input. Changes in mitochondrial content corresponded to survival in vivo among the 4 strains. Calcium-induced mitochondrial swelling was strain dependent. Isolated mitochondria from BALB/c mice were significantly more sensitive to calcium overload than mitochondria from C57BL/6 mice. Maternal input partially influenced the recovery effect of radiation on calcium-induced mitochondrial swelling in F1 hybrids; the hybrid with a radiosensitive maternal lineage exhibited a lower rate of recovery. Hybrids had a survival rate that was biased toward maternal input. mtDNA content and mitochondrial permeability transition pores (MPTP) measured in these strains before irradiation reflected a dominant input from the parent. After irradiation, the MPTP opened sooner in radiosensitive and hybrid strains, likely triggering intrinsic apoptotic pathways. These findings have important implications for translation into predictors of radiation sensitivity/resistance. PMID:24688546

  3. Influence of some methodological factors on the radiosensitivity of the mouse zygote

    SciTech Connect

    Jacquet, P.; Grinfeld, S. )

    1990-10-01

    The experiments reported here were undertaken to investigate the influence of some methodological factors on the radiosensitivity of the mouse zygote. The following factors were studied: (1) the use of natural or hormone-stimulated ovulation; (2) the procedure followed for fertilization:mating overnight, or only during a short period in the morning after all oocytes have been ovulated, in vitro fertilization; (3) the type of irradiation, i.e., in vivo or in vitro irradiation. The radiosensitivity of the zygotes was estimated under the different experimental conditions by measuring the ability of the irradiated embryos to cleave and to develop further to the blastocyst stage. Our results suggest that the protocols used for mating and fertilization probably have a greater influence on embryonic survival following irradiation than the use of gonadotropins to stimulate ovulation. The highest degree of synchrony in the development of the embryos is achieved by restricting mating to a short period or by using in vitro fertilization. The very low LD50s obtained under such synchronous conditions confirm the high radiosensitivity of the mouse zygote at the early pronuclear stage. Comparison between the effects of in vivo and in vitro irradiation does not indicate a greater radiosensitivity of the embryo irradiated in vitro in comparison to the embryo irradiated in vivo.

  4. In Vitro-Pooled shRNA Screening to Identify Determinants of Radiosensitivity.

    PubMed

    Ceroni, Alessandro; Higgins, Geoff S; Ebner, Daniel V

    2016-01-01

    Short hairpin RNA (shRNA)-pooled screening is a valuable and cost-effective tool for assaying the contribution of individual genes to cell viability and proliferation on a genomic scale. Here we describe the key considerations for the design and execution of a pooled shRNA screen to identify determinants of radiosensitivity. PMID:27581288

  5. Different radiosensitivities of mast-cell precursors in the bone marrow and skin of mice

    SciTech Connect

    Kitamura, Y.; Yokoyama, M.; Sonoda, T.; Mori, K.J.

    1983-01-01

    Although tissue mast cells are derived from the bone marrow, some descendants of bone marrow-derived precursors retain the ability to proliferate and differentiate into mast cells even after localization in the skin. The purpose of the present study was to determine the D0 values for mast-cell precursors in the bone marrow and those localized in the skin. Bone marrow cells were removed from (WB X C57BL/6)F1-+/+ mice after various doses of irradiation and injected into the skin of the congenic W/Wv mice which were genetically without mast cells. Radiosensitivity of mast-cell precursors in the bone marrow was evaluated by determining the proportion of the injection sites at which mast cells did not appear. For the assay of the radiosensitivity of mast-cell precursors localized in the skin, pieces of skin were removed from beige C57BL/6 (bgJ/bgJ. Chediak-Higashi syndrome) mice after various doses of irradiation and grafted onto the back of the normal C57BL/6 mice. Radiosensitivity of mast-cell precursors in the skin was evaluated by determining the decrease of beige-type mast cells which possessed giant granules. Mast-cell precursors in the bone marrow were much more radiosensitive than those localized in the skin. D0 value was about 100 rad for the former and about 800 rad for the latter.

  6. Coupling of the radiosensitivity of melanocyte stem cells to their dormancy during the hair cycle.

    PubMed

    Ueno, Makiko; Aoto, Takahiro; Mohri, Yasuaki; Yokozeki, Hiroo; Nishimura, Emi K

    2014-07-01

    Current studies have revealed that stem cells are more radiosensitive than mature cells. As somatic stem cells are mostly kept in a quiescent state, this conflicts with Bergonié and Tribondeau's law that actively mitotic cells are the most radiosensitive. In this study, we focused on hair graying to understand the stress-resistance of melanocyte stem cells (McSCs). We used Dct-H2B-GFP transgenic mice which enables the stable visualization of McSCs and an anti-Kit monoclonal antibody which selectively eradicates amplifying McSCs. The results demonstrate that quiescent McSCs are rather radiosensitive, but the coexistence of non-quiescent McSCs provides the stem cell pool with radioresistance. The irradiated quiescent McSCs prematurely differentiate in the niche upon their activation without sufficiently renewing themselves for cyclic hair pigmentation. These data indicate that tissue radiosensitivity is largely dependent on the state of somatic stem cells under their local microenvironment. PMID:24730534

  7. Radiosensitization by nicotinamide in tumors and normal tissues: the importance of tissue oxygenation status

    SciTech Connect

    Horsman, M.R.; Hansen, P.V.; Overgaard, J.

    1989-05-01

    Nicotinamide induced radiosensitization of tumors has been suggested to be a consequence of a reduction in tumor hypoxia. We have investigated the possibility that nicotinamide may produce significant radiosensitization in a normal tissue in which the radiation response is also influenced by hypoxia. The normal tissue studied was testis and radiation damage was assessed by measuring survival of spermatogonial stem cells. The radiosensitizing action of nicotinamide in testis was compared to that observed in a C3H mammary carcinoma when assayed by both regrowth delay and local tumor control. Our results show that nicotinamide (1000 mg/kg; i.p.) enhanced radiation damage in both tissue types when the radiation was given up to at least 3 hr after drug injection. Enhancement ratios obtained when the drug and radiation were separated by a 1 hr time interval were between 1.1 to 1.2 for the testis and 1.0 to 1.5 for the tumor. The results suggest that nicotinamide will produce radiosensitization in testis, but the effect is small and less than that observed in tumors.

  8. Simultaneous Inhibition of EGFR and PI3K Enhances Radiosensitivity in Human Breast Cancer

    SciTech Connect

    Li Ping; Zhang Qing; Torossian, Artour; Li Zhaobin; Xu Wencai; Lu Bo; Fu Shen

    2012-07-01

    Purpose: Mutations in the epidermal growth factor receptor (EGFR)/phosphoinositide 3-kinase (PI3K)/Akt signaling transduction pathway are common in cancer. This pathway is imperative to the radiosensitivity of cancer cells. We aimed to investigate the radiosensitizing effects of the simultaneous inhibition of EGFR and PI3K in breast cancer cells. Methods and Materials: MCF-7 cell lines with low expression of EGFR and wild-type PTEN and MDA-MB-468 cell lines with high expression of EGFR and mutant PTEN were used. The radiosensitizing effects by the inhibition of EGFR with AG1478 and/or PI3K with Ly294002 were determined by colony formation assay, Western blot was used to investigate the effects on downstream signaling. Flow cytometry was used for apoptosis and cell cycle analysis. Mice-bearing xenografts of MDA-MB-468 breast cancer cells were also used to observe the radiosensitizing effect. Results: Simultaneous inhibition of EGFR and PI3K greatly enhanced radiosensitizing effect in MDA-MB-468 in terms of apoptosis and mitotic death, either inhibition of EGFR or PI3K alone could enhance radiosensitivity with a dose-modifying factor (DMF{sub SF2}) of 1.311 and 1.437, radiosensitizing effect was further enhanced by simultaneous inhibition of EGFR and PI3K with a DMF{sub SF2} at 2.698. DNA flow cytometric analysis indicated that dual inhibition combined with irradiation significantly induced G0/G1 phase arrest in MDA-MB-468 cells. The expression of phosphor-Akt and phosphor-Erk1/2 (induced by irradiation and PI3K inhibitor) were fully attenuated by simultaneous treatment with both inhibitors in combination with irradiation. In addition, dual inhibition combined with irradiation induced dramatic tumor growth delay in MDA-MB-468 xenografts. Conclusions: Our study indicated that simultaneous inhibition of EGFR and PI3K could further sensitize the cancer cells to irradiation compared to the single inhibitor with irradiation in vitro and in vivo. The approach may have

  9. Gefitinib Radiosensitizes Stem-Like Glioma Cells: Inhibition of Epidermal Growth Factor Receptor-Akt-DNA-PK Signaling, Accompanied by Inhibition of DNA Double-Strand Break Repair

    SciTech Connect

    Kang, Khong Bee; Zhu Congju; Wong Yinling; Gao Qiuhan; Ty, Albert; Wong, Meng Cheong

    2012-05-01

    Purpose: We compared radiosensitivity of brain tumor stem cells (BTSCs) with matched nonstem glioma cells, and determined whether gefitinib enhanced BTSC radiosensitivity by inhibiting epidermal growth factor receptor (EGFR)-Akt-DNA-dependent protein kinase (DNA-PK) signaling, followed by enhanced DNA double-stand breaks (DSBs) and inhibition of DSB repair. Methods and Materials: Radiosensitivity of stem-like gliomaspheres and nonstem glioma cells (obtained at patient neurosurgical resection) were evaluated by clonogenic assays, {gamma}-H{sub 2}AX immunostaining and cell cycle distribution. Survival of irradiated and nonirradiated NOD-SCID mice intracranially implanted with stem-like gliomaspheres were monitored. Glioma cells treated with gefitinib, irradiation, or both were assayed for clonogenic survival, {gamma}-H{sub 2}AX immunostaining, DNA-PKcs expression, and phosphorylation of EGFR and Akt. Results: Stem-like gliomaspheres displayed BTSC characteristics of self-renewal; differentiation into lineages of neurons, oligodendrocytes, and astrocytes; and initiation of glioma growth in NOD-SCID mice. Irradiation dose-dependently reduced clonogenic survival, induced G{sub 2}/M arrest and increased {gamma}-H{sub 2}AX immunostaining of nonstem glioma cells, but not stem-like gliomaspheres. There was no difference in survival of irradiated and nonirradiated mice implanted with stem-like gliomaspheres. The addition of gefitinib significantly inhibited clonogenic survival, increased {gamma}-H{sub 2}AX immunostaining, and reduced DNA-PKcs expression of irradiated stem-like gliomaspheres, without affecting irradiated-nonstem glioma cells. Gefitinib alone, and when combined with irradiation, inhibited phosphorylation of EGFR (Y1068 and Y1045) and Akt (S473) in stem-like gliomaspheres. In nonstem glioma cells, gefitinib alone inhibited EGFR Y1068 phosphorylation, with further inhibition by combined gefitinib and irradiation. Conclusions: Stem-like gliomaspheres are

  10. Enhancement of P53-Mutant Human Colorectal Cancer Cells Radiosensitivity by Flavonoid Fisetin

    SciTech Connect

    Chen Wenshu; Lee Yijang; Yu Yichu; Hsaio Chinghui

    2010-08-01

    Purpose: The aim of this study was to investigate whether fisetin is a potential radiosensitizer for human colorectal cancer cells, which are relatively resistant to radiotherapy. Methods and Materials: Cell survival was examined by clonogenic survival assay, and DNA fragmentation was assessed by terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling assay. The effects of treatments on cell cycle distribution and apoptosis were examined by flow cytometry. Western blot analysis was performed to ascertain the protein levels of {gamma}-H2AX, phospho-Chk2, active caspase-3, PARP cleavage, phospho-p38, phospho-AKT, and phospho-ERK1/2. Results: Fisetin pretreatment enhanced the radiosensitivity of p53-mutant HT-29 human colorectal cancer cells but not human keratocyte HaCaT cells; it also prolonged radiation-induced G{sub 2}/M arrest, enhanced radiation-induced cell growth arrest in HT-29 cells, and suppressed radiation-induced phospho-H2AX (Ser-139) and phospho-Chk2 (Thr-68) in p53-mutant HT-29 cells. Pretreatment with fisetin enhanced radiation-induced caspase-dependent apoptosis in HT-29 cells. Fisetin pretreatment augmented radiation-induced phosphorylation of p38 mitogen-activated protein kinase, which is involved in caspase-mediated apoptosis, and SB202190 significantly reduced apoptosis and radiosensitivity in fisetin-pretreated HT-29 cells. By contrast, both phospho-AKT and phospho-ERK1/2, which are involved in cell proliferation and antiapoptotic pathways, were suppressed after irradiation combined with fisetin pretreatment. Conclusions: To our knowledge, this study is the first to provide evidence that fisetin exerts a radiosensitizing effect in p53-mutant HT-29 cells. Fisetin could potentially be developed as a novel radiosensitizer against radioresistant human cancer cells.

  11. Iodine-125-labeled cRGD-gold nanoparticles as tumor-targeted radiosensitizer and imaging agent

    NASA Astrophysics Data System (ADS)

    Su, Ning; Dang, Yajie; Liang, Guangli; Liu, Guizhi

    2015-04-01

    Research interests on radiosensitive property of gold nanoparticles (GNPs) are rapidly raised because of the extensively proved in vitro effectiveness and clinical necessity. However, the issue of targeted accumulation of GNPs in tumor tissues hindered the transference to in vivo applications. In this study, hybrid nano-sized cyclic Arg-Gly-Asp-conjugated GNPs (cRGD-GNPs) integrated with radioactive iodine-125 was fabricated as tumor-targeted radiosensitizer. Therapeutic effects, including acute apoptosis (2 days post treatment) and long-term influence (up to 21 days), were investigated on NCI-H446 tumor-bearing mice via Tc-99 m-Annexin V SPECT and volume measurements, respectively. Apoptosis and volume loss were consistent in showing that tumor growth was effectively suppressed via the treatment of 125I-cRGD-GNP sensitized radiotherapy (RT), a more significantly radiosensitive effect than the treatment of non-targeted GNPs with RT, RT treatment alone, and no treatment. SPECT/CT images showed that the uptake of cRGD-GNPs by tumor tissues reached the peak target/non-target value of 4.76 at around 2 h post injection, and dynamic radioactivity monitoring showed that 125I-cRGD-GNPs maintained about 2.5% of injected dosage at 55 h post injection. For long-term influence, a significant radiosensitized RT-induced volume loss was observed. Hence, cyclic RGD conjugation makes the GNP-based radiosensitizer tumor targeting, offering a new modality for enhancing radiotherapeutic efficacy. Additionally, the introduction of I-125 serves as both a therapeutic factor and a radiotracer for in vivo tracking of GNPs.

  12. Simulation on the molecular radiosensitization effect of gold nanoparticles in cells irradiated by x-rays

    NASA Astrophysics Data System (ADS)

    Xie, W. Z.; Friedland, W.; Li, W. B.; Li, C. Y.; Oeh, U.; Qiu, R.; Li, J. L.; Hoeschen, C.

    2015-08-01

    Abundant studies have focused on the radiosensitization effect of gold nanoparticles (GNPs) in the cellular environment with x-ray irradiation. To better understand the physical foundation and to initially study the molecular radiosensitization effect within the nucleus, a simple cell model with detailed DNA structure in the central nucleus was set up and complemented with different distributions of single and multiple GNPs in this work. With the biophysical Monte Carlo simulation code PARTRAC, the radiosensitization effects on both physical quantities and primary biological responses (DNA strand breaks) were simulated. The ratios of results under situations with GNPs compared to those without GNPs were defined as the enhancement factors (EFs). The simulation results show that the presence of GNP can cause a notable enhancement effect on the energy deposition within a few micrometers from the border of GNP. The greatest upshot appears around the border and is mostly dominated by Auger electrons. The enhancement effect on the DNA strand breakage becomes smaller because of the DNA distribution inside the nucleus, and the corresponding EFs are between 1 and 1.5. In the present simulation, multiple GNPs on the nucleus surface, the 60 kVp x-ray spectrum and the diameter of 100 nm are relatively more effective conditions for both physical and biological radiosensitization effects. These results preliminarily indicate that GNP can be a good radiosensitizer in x-ray radiotherapy. Nevertheless, further biological responses (repair process, cell survival, etc) need to be studied to give more accurate evaluation and practical proposal on GNP’s application in clinical treatment.

  13. Garcinol, a Histone Acetyltransferase Inhibitor, Radiosensitizes Cancer Cells by Inhibiting Non-Homologous End Joining

    SciTech Connect

    Oike, Takahiro; Ogiwara, Hideaki; Torikai, Kohta; Nakano, Takashi; Yokota, Jun; Kohno, Takashi

    2012-11-01

    Purpose: Non-homologous end joining (NHEJ), a major pathway used to repair DNA double-strand breaks (DSBs) generated by ionizing radiation (IR), requires chromatin remodeling at DSB sites through the acetylation of histones by histone acetyltransferases (HATs). However, the effect of compounds with HAT inhibitory activities on the DNA damage response (DDR), including the NHEJ and cell cycle checkpoint, as well as on the radiosensitivity of cancer cells, remains largely unclear. Here, we investigated whether garcinol, a HAT inhibitor found in the rinds of Garcinia indica fruit (called mangosteens), has effects on DDR, and whether it can be used for radiosensitization. Methods and Materials: The following assays were used to examine the effect of garcinol on the inhibition of DSB repair, including the following: a conventional neutral comet assay; a cell-based assay recently developed by us, in which NHEJ repair of DSBs on chromosomal DNA was evaluated; the micrococcal nuclease sensitivity assay; and immunoblotting for autophosphorylation of DNA-dependent protein kinase catalytic subunit (DNA-PKcs). We assessed the effect of garcinol on the cell cycle checkpoint after IR treatment by analyzing the phosphorylation levels of checkpoint kinases CHK1 and CHK2 and histone H3, and by cell cycle profile analysis using flow cytometry. The radiosensitizing effect of garcinol was assessed by a clonogenic survival assay, whereas its effects on apoptosis and senescence were examined by annexin V and senescence-associated {beta}-galactosidase (SA-{beta}-Gal) staining, respectively. Results: We found that garcinol inhibits DSB repair, including NHEJ, without affecting cell cycle checkpoint. Garcinol radiosensitized A549 lung and HeLa cervical carcinoma cells with dose enhancement ratios (at 10% surviving fraction) of 1.6 and 1.5, respectively. Cellular senescence induced by IR was enhanced by garcinol. Conclusion: These results suggest that garcinol is a radiosensitizer that

  14. AZD2014 Radiosensitizes Oral Squamous Cell Carcinoma by Inhibiting AKT/mTOR Axis and Inducing G1/G2/M Cell Cycle Arrest

    PubMed Central

    Yu, Chih-Chia; Huang, Hsien-bin; Hung, Shih-Kai; Liao, Hui-Fen; Lee, Ching-Chih; Lin, Hon-Yi; Li, Szu-Chin; Ho, Hsu-Chueh; Hung, Chung-Lin; Su, Yu-Chieh

    2016-01-01

    Background Oral squamous cell carcinoma (OSCC) is one of the most common malignant neoplasms in Taiwan. Activation of the mTOR signaling pathway has been linked to decreased radiation responsiveness in human oral cancer, thus it limits efficacy of radiotherapy. To address this question, we investigated the effect of AZD2014, a novel small molecular ATP-competitive inhibitor of mTORC1 and mTORC2 kinase, as a radiosensitizer in primary OSCC and OSCC-derived cell line models. Methods We isolated primary tumor cells from OSCC tissues and cell lines. AZD2014 was administered with and without ionizing radiation. The radiosensitizing effect of AZD2014 were then assessed using cell viability assays, clonogenic survival assays, and cell cycle analyses. Western blotting was used to detect protein expression. Results Combination treatment with AZD2014 and irradiation resulted in significant reduction in OSCC cell line and primary OSCC cell colony formation due to the enhanced inhibition of AKT and both mTORC1 and mTORC2 activity. Pre-treatment with AZD2014 in irradiated oral cancer cells induced tumor cell cycle arrest at the G1 and G2/M phases, which led to disruption of cyclin D1-CDK4 and cyclin B1-CDC2 complexes. Moreover, AZD2014 synergized with radiation to promote both apoptosis and autophagy by increasing caspase-3 and LC3 in primary OSCC cells. Conclusions These findings suggest that in irradiated OSCC cells, co-treatment with AZD2014, which targets mTORC1 and mTORC2 blockade, is an effective radiosensitizing strategy for oral squamous cell carcinoma. PMID:27031247

  15. Microsatellite polymorphisms in DNA repair genes XRCC1, XRCC3 and XRCC5 in patients with gynecological tumors: association with late clinical radiosensitivity and cancer incidence.

    PubMed

    De Ruyck, K; Wilding, C S; Van Eijkeren, M; Morthier, R; Tawn, E J; Thierens, H

    2005-09-01

    This study investigates the association of microsatellite polymorphisms in XRCC1, XRCC3 and XRCC5 with the development of late radiation-induced radiotherapy reactions and examines the correlation between these microsatellites and cancer incidence. Sixty-two women with cervical or endometrial cancer treated with radiotherapy were included in the study. According to the CTCAEv3.0 scale, 22 patients showed late adverse radiotherapy reactions (grade 2 or more). PCR on lymphocyte DNA followed by automated fragment analysis was performed to examine the number of tandem repeat units at each locus. No significant association was found between the repeat length at any of the microsatellites in XRCC1, XRCC3 or XRCC5 and the incidence of late radiotherapy complications. Since higher odds ratios (ORs) were found for the rare XRCC1 [AC]11 and [AC]21 repeats (OR = 2.65, P = 0.325 and OR = 8.67, P = 0.093, respectively), the possible involvement of these small and large repeats in clinical radiosensitivity cannot be completely ruled out. When specific numbers of repeats were examined, no significant correlation was found between the microsatellite repeat length in XRCC1 and XRCC5 and cancer incidence. A weak correlation between XRCC3 [AC]16 homozygotes and cancer incidence was found (OR = 2.56, P = 0.055). A large-scale multicenter study of cancer patients with a high number of radiosensitive individuals is needed to clarify the value of rare polymorphic microsatellite repeats in XRCC1 and XRCC3 as a biomarker of clinical radiosensitivity or increased cancer risk. PMID:16137195

  16. Nonhomologous end-joining repair plays a more important role than homologous recombination repair in defining radiosensitivity after exposure to high-LET radiation.

    PubMed

    Takahashi, Akihisa; Kubo, Makoto; Ma, Hongyu; Nakagawa, Akiko; Yoshida, Yukari; Isono, Mayu; Kanai, Tatsuaki; Ohno, Tatsuya; Furusawa, Yoshiya; Funayama, Tomoo; Kobayashi, Yasuhiko; Nakano, Takashi

    2014-09-01

    DNA double-strand breaks (DSBs) induced by ionizing radiation pose a major threat to cell survival. The cell can respond to the presence of DSBs through two major repair pathways: homologous recombination (HR) and nonhomologous end joining (NHEJ). Higher levels of cell death are induced by high-linear energy transfer (LET) radiation when compared to low-LET radiation, even at the same physical doses, due to less effective and efficient DNA repair. To clarify whether high-LET radiation inhibits all repair pathways or specifically one repair pathway, studies were designed to examine the effects of radiation with different LET values on DNA DSB repair and radiosensitivity. Embryonic fibroblasts bearing repair gene (NHEJ-related Lig4 and/or HR-related Rad54) knockouts (KO) were used and their responses were compared to wild-type cells. The cells were exposed to X rays, spread-out Bragg peak (SOBP) carbon ion beams as well as with carbon, iron, neon and argon ions. Cell survival was measured with colony-forming assays. The sensitization enhancement ratio (SER) values were calculated using the 10% survival dose of wild-type cells and repair-deficient cells. Cellular radiosensitivity was listed in descending order: double-KO cells > Lig4-KO cells > Rad54-KO cells > wild-type cells. Although Rad54-KO cells had an almost constant SER value, Lig4-KO cells showed a high-SER value when compared to Rad54-KO cells, even with increasing LET values. These results suggest that with carbon-ion therapy, targeting NHEJ repair yields higher radiosensitivity than targeting homologous recombination repair. PMID:25117625

  17. Radiosensitization by fullerene-C60 dissolved in squalene on human malignant melanoma through lipid peroxidation and enhanced mitochondrial membrane potential

    NASA Astrophysics Data System (ADS)

    Kato, Shinya; Kimura, Masatsugu; Miwa, Nobuhiko

    2014-04-01

    We examined fullerene-C60 dissolved in squalene (C60/Sqe) for the ability to potentiate the radiosensitization under X-ray irradiation on human malignant melanoma HMV-II cells, which were treated with C60/Sqe and thereafter irradiated with X-ray. The cell proliferation for C60/Sqe was inhibited more markedly than for Sqe alone. Meanwhile, cell proliferation was almost unaltered for C60/squalane (Sqa) or Sqa, a hydrogenated form of Sqe, as compared to no-additive control. Thus radiosensitization of C60/Sqe is attributed to peroxidation of unsaturated bonds of squalene by X-ray-excited C60 in contrast to squalane. The fluorescence images of HMV-II cells stained with Rhodamine123, an indicator for mitochondrial membrane potential, were monitored for 6 h after X-ray irradiation. C60/Sqe obviously exhibited more augmented fluorescence intensity on perinuclear region of HMV-II cells than Sqe alone. TBARS assay showed that the lipid peroxidation level as malondialdehyde-equivalent increased by combination of C60/Sqe and X-ray dose-dependently on X-ray doses. C60/Sqe exhibited lipid peroxidation more markedly by 1.2-fold than Sqe alone. Thus the level of lipid peroxidation of squalene was sufficiently higher in C60/Sqe than in Sqe in the absence of C60 under X-ray irradiation, suggesting the combination of C60/Sqe and X-ray irradiation induced radiosensitization on HMV-II cells by peroxidation of absorbed Sqe in mitochondrial membrane via oxidative stress mediated by fullerene-C60.

  18. Comparison of Radiosensitizing Effects of the mTOR Inhibitor CCI-779 to Cisplatin in Experimental Models of Head and Neck Squamous Cell Carcinoma

    PubMed Central

    Ekshyyan, Oleksandr; Rong, Youhua; Rong, Xiaohua; Pattani, Kavita M.; Abreo, Fleurette; Caldito, Gloria; Chang, John Kai Siung; Ampil, Federico; Glass, Jonathan; Nathan, Cherie-Ann O.

    2009-01-01

    Purpose To determine if the mTOR inhibitor CCI-779 can sensitize head and neck squamous cell carcinoma (HNSCC) to radiotherapy (XRT) and compare the radiosensitizing effects to cisplatin with its known considerable toxicity. Experimental Design Radiosensitizing effects of CCI-779 were assayed on HNSCC cell lines in vitro. CCI-779 (5mg/kg), cisplatin (1 mg/kg) and XRT (2 Gy) alone and in combination were evaluated for antitumor activity in mice bearing FaDu and SCC40 xenografts. Effects of CCI-779 on radiation-induced activation of the Akt/mTOR pathway were analyzed. Results Although CCI-779 did not sensitize HNSCC cells to ionizing radiation in vitro, combination of CCI-779 and XRT significantly augmented the in vivo tumor growth inhibitory effects of XRT and CCI-779 (P<0.05). In addition CCI-779+XRT suppressed tumor growth more effectively than cisplatin+XRT (P<0.05). CCI-779+XRT significantly improved survival compared to XRT alone in both cisplatin-sensitive FaDu (P<0.01) and cisplatin-resistant SCC40 xenograft mice (P<0.05). There were no additional benefits of adding cisplatin to CCI-779+XRT. CCI-779 significantly attenuated irradiation-induced upregulation of the mTOR pathway, increased apoptosis and displayed potent antiangiogenic activity in FaDu xenografts that was further enhanced by its combination with radiotherapy (P<0.05) which may explain the mechanism of its selective radiosensitizing effects in vivo and not in vitro. Conclusions Antitumor activity of radiotherapy was enhanced when combined with CCI-779 in HNSCC xenograft model. CCI-779+XRT showed antitumor activity superior to conventional chemoradiotherapy with cisplatin. These results pave the way for clinical trials utilizing molecular targeted therapy with CCI-779 in combination with radiotherapy for HNSCC treatment. PMID:19625495

  19. Pharmacological Inhibition of the Protein Kinase MRK/ZAK Radiosensitizes Medulloblastoma.

    PubMed

    Markowitz, Daniel; Powell, Caitlin; Tran, Nhan L; Berens, Michael E; Ryken, Timothy C; Vanan, Magimairajan; Rosen, Lisa; He, Mingzu; Sun, Shan; Symons, Marc; Al-Abed, Yousef; Ruggieri, Rosamaria

    2016-08-01

    Medulloblastoma is a cerebellar tumor and the most common pediatric brain malignancy. Radiotherapy is part of the standard care for this tumor, but its effectiveness is accompanied by significant neurocognitive sequelae due to the deleterious effects of radiation on the developing brain. We have previously shown that the protein kinase MRK/ZAK protects tumor cells from radiation-induced cell death by regulating cell-cycle arrest after ionizing radiation. Here, we show that siRNA-mediated MRK depletion sensitizes medulloblastoma primary cells to radiation. We have, therefore, designed and tested a specific small molecule inhibitor of MRK, M443, which binds to MRK in an irreversible fashion and inhibits its activity. We found that M443 strongly radiosensitizes UW228 medulloblastoma cells as well as UI226 patient-derived primary cells, whereas it does not affect the response to radiation of normal brain cells. M443 also inhibits radiation-induced activation of both p38 and Chk2, two proteins that act downstream of MRK and are involved in DNA damage-induced cell-cycle arrest. Importantly, in an animal model of medulloblastoma that employs orthotopic implantation of primary patient-derived UI226 cells in nude mice, M443 in combination with radiation achieved a synergistic increase in survival. We hypothesize that combining radiotherapy with M443 will allow us to lower the radiation dose while maintaining therapeutic efficacy, thereby minimizing radiation-induced side effects. Mol Cancer Ther; 15(8); 1799-808. ©2016 AACR. PMID:27207779

  20. Hypoxia-induced p53 modulates both apoptosis and radiosensitivity via AKT

    PubMed Central

    Leszczynska, Katarzyna B.; Foskolou, Iosifina P.; Abraham, Aswin G.; Anbalagan, Selvakumar; Tellier, Céline; Haider, Syed; Span, Paul N.; O’Neill, Eric E.; Buffa, Francesca M.; Hammond, Ester M.

    2015-01-01

    Restoration of hypoxia-induced apoptosis in tumors harboring p53 mutations has been proposed as a potential therapeutic strategy; however, the transcriptional targets that mediate hypoxia-induced p53-dependent apoptosis remain elusive. Here, we demonstrated that hypoxia-induced p53-dependent apoptosis is reliant on the DNA-binding and transactivation domains of p53 but not on the acetylation sites K120 and K164, which, in contrast, are essential for DNA damage–induced, p53-dependent apoptosis. Evaluation of hypoxia-induced transcripts in multiple cell lines identified a group of genes that are hypoxia-inducible proapoptotic targets of p53, including inositol polyphosphate-5-phosphatase (INPP5D), pleckstrin domain–containing A3 (PHLDA3), sulfatase 2 (SULF2), B cell translocation gene 2 (BTG2), cytoplasmic FMR1-interacting protein 2 (CYFIP2), and KN motif and ankyrin repeat domains 3 (KANK3). These targets were also regulated by p53 in human cancers, including breast, brain, colorectal, kidney, bladder, and melanoma cancers. Downregulation of these hypoxia-inducible targets associated with poor prognosis, suggesting that hypoxia-induced apoptosis contributes to p53-mediated tumor suppression and treatment response. Induction of p53 targets, PHLDA3, and a specific INPP5D transcript mediated apoptosis in response to hypoxia through AKT inhibition. Moreover, pharmacological inhibition of AKT led to apoptosis in the hypoxic regions of p53-deficient tumors and consequently increased radiosensitivity. Together, these results identify mediators of hypoxia-induced p53-dependent apoptosis and suggest AKT inhibition may improve radiotherapy response in p53-deficient tumors. PMID:25961455

  1. Standard sub-thermoneutral caging temperature influences radiosensitivity of hematopoietic stem and progenitor cells.

    PubMed

    Povinelli, Benjamin J; Kokolus, Kathleen M; Eng, Jason W-L; Dougher, Christopher W; Curtin, Leslie; Capitano, Maegan L; Sailsbury-Ruf, Christi T; Repasky, Elizabeth A; Nemeth, Michael J

    2015-01-01

    The production of new blood cells relies on a hierarchical network of hematopoietic stem and progenitor cells (HSPCs). To maintain lifelong hematopoiesis, HSPCs must be protected from ionizing radiation or other cytotoxic agents. For many years, murine models have been a valuable source of information regarding factors that either enhance or reduce the survival of HSPCs after exposure of marrow to ionizing radiation. In a recent series of studies, however, it has become clear that housing-related factors such as the cool room temperature required for laboratory mice can exert a surprising influence on the outcome of experiments. Here we report that the mild, but chronic cold-stress endured by mice housed under these conditions exerts a protective effect on HSPCs after both non-lethal and lethal doses of total body irradiation (TBI). Alleviation of this cold-stress by housing mice at a thermoneutral temperature (30°C) resulted in significantly greater baseline radiosensitivity to a lethal dose of TBI with more HSPCs from mice housed at thermoneutral temperature undergoing apoptosis following non-lethal TBI. Cold-stressed mice have elevated levels of norepinephrine, a key molecule of the sympathetic nervous system that binds to β-adrenergic receptors. We show that blocking this signaling pathway in vivo through use of the β-blocker propanolol completely mitigates the protective effect of cold-stress on HSPC apoptosis. Collectively this study demonstrates that chronic stress endured by the standard housing conditions of laboratory mice increases the resistance of HSPCs to TBI-induced apoptosis through a mechanism that depends upon β-adrenergic signaling. Since β-blockers are commonly prescribed to a wide variety of patients, this information could be important when predicting the clinical impact of HSPC sensitivity to TBI. PMID:25793392

  2. Multiple dose study of the combined radiosensitizers Ro 03-8799 (pimonidazole) and SR 2508 (etanidazole)

    SciTech Connect

    Bleehen, N.M.; Newman, H.F.; Maughan, T.S.; Workman, P.

    1989-04-01

    The hypoxic cell radiosensitizers Ro 03-8799 and SR 2508 have different clinical toxicities. The former produces an acute but transient central nervous system syndrome, whereas the latter produces cumulative peripheral neuropathy. Following single dose studies, an escalating multiple dose schedule using both drugs in combination showed no unexpected adverse reactions at lower doses. This study identifies the clinical tolerance and pharmacokinetics when doses in the region of the maximal tolerated dose are given to 26 patients receiving infusions of 0.75 g/m2 Ro 03-8799 and 2 g/m2 SR 2508 three times per week. At 15 doses, 3/4 patients experienced WHO grade 2 peripheral neuropathy, whereas at 12 doses 1/9 developed grade 2 and 6/9 developed grade 1 neuropathies. This represents a lower dose of SR 2508 than can be given alone suggesting that some interaction between the two drugs does exist in terms of chronic peripheral neurotoxicity. Pharmacokinetic studies show no adverse interactions between the two drugs and minimal inter-patient variation. From bivariate analysis, cumulative AUC for Ro 03-8799 has the most significant correlation with the development of peripheral neuropathy. Tumor drug concentrations normalized to the administered dose show mean values of 34 micrograms/g Ro 03-8799 and 76 micrograms/g SR 2508 30 minutes after infusion. These could be expected to produce a single dose sensitizer enhancement ratio of 1.5. The combination of the two sensitizers at the maximum tolerable dose may be expected to give an increased therapeutic efficacy over either drug alone.

  3. Radiosensitizing Effect of a Phenylbutyrate-Derived Histone Deacetylase Inhibitor in Hepatocellular Carcinoma

    SciTech Connect

    Lu, Yen-Shen; Chou, Chia-Hung; Tzen, Kai-Yuan; Gao, Ming; Cheng, Ann-Lii; Kulp, Samuel K.; Cheng, Jason Chia-Hsien

    2012-06-01

    Purpose: Radiotherapy is integrated into the multimodal treatment of localized hepatocellular carcinoma (HCC) refractory to conventional treatment. Tumor control remains unsatisfactory and the sublethal effect associates with secondary spread. The use of an effective molecularly targeted agent in combination with radiotherapy is a potential therapeutic approach. Our aim was to assess the effect of combining a phenylbutyrate-derived histone deacetylase (HDAC) inhibitor, AR-42, with radiotherapy in in vitro and in vivo models of human HCC. Methods and Materials: Human HCC cell lines (Huh-7 and PLC-5) were used to evaluate the in vitro synergism of combining AR-42 with irradiation. Flow cytometry analyzed the cell cycle changes, whereas Western blot investigated the protein expressions after the combined treatment. Severe combined immunodeficient (SCID) mice bearing ectopic and orthotopic HCC xenografts were treated with AR-42 and/or radiotherapy for the in vivo response. Results: AR-42 significantly enhanced radiation-induced cell death by the inhibition of the DNA end-binding activity of Ku70, a highly versatile regulatory protein for DNA repair, telomere maintenance, and apoptosis. In ectopic xenografts of Huh-7 and PLC-5, pretreatment with AR-42 significantly enhanced the tumor-suppressive effect of radiotherapy by 48% and 66%, respectively. A similar combinatorial effect of AR-42 (10 and 25 mg/kg) and radiotherapy was observed in Huh-7 orthotopic model of tumor growth by 52% and 82%, respectively. This tumor suppression was associated with inhibition of intratumoral Ku70 activity as well as reductions in markers of HDAC activity and proliferation, and increased apoptosis. Conclusion: AR-42 is a potent, orally bioavailable inhibitor of HDAC with therapeutic value as a radiosensitizer of HCC.

  4. Standard Sub-Thermoneutral Caging Temperature Influences Radiosensitivity of Hematopoietic Stem and Progenitor Cells

    PubMed Central

    Eng, Jason W.-L.; Dougher, Christopher W.; Curtin, Leslie; Capitano, Maegan L.; Sailsbury-Ruf, Christi T.; Repasky, Elizabeth A.; Nemeth, Michael J.

    2015-01-01

    The production of new blood cells relies on a hierarchical network of hematopoietic stem and progenitor cells (HSPCs). To maintain lifelong hematopoiesis, HSPCs must be protected from ionizing radiation or other cytotoxic agents. For many years, murine models have been a valuable source of information regarding factors that either enhance or reduce the survival of HSPCs after exposure of marrow to ionizing radiation. In a recent series of studies, however, it has become clear that housing-related factors such as the cool room temperature required for laboratory mice can exert a surprising influence on the outcome of experiments. Here we report that the mild, but chronic cold-stress endured by mice housed under these conditions exerts a protective effect on HSPCs after both non-lethal and lethal doses of total body irradiation (TBI). Alleviation of this cold-stress by housing mice at a thermoneutral temperature (30°C) resulted in significantly greater baseline radiosensitivity to a lethal dose of TBI with more HSPCs from mice housed at thermoneutral temperature undergoing apoptosis following non-lethal TBI. Cold-stressed mice have elevated levels of norepinephrine, a key molecule of the sympathetic nervous system that binds to β-adrenergic receptors. We show that blocking this signaling pathway in vivo through use of the β-blocker propanolol completely mitigates the protective effect of cold-stress on HSPC apoptosis. Collectively this study demonstrates that chronic stress endured by the standard housing conditions of laboratory mice increases the resistance of HSPCs to TBI-induced apoptosis through a mechanism that depends upon β-adrenergic signaling. Since β-blockers are commonly prescribed to a wide variety of patients, this information could be important when predicting the clinical impact of HSPC sensitivity to TBI. PMID:25793392

  5. Ionizing Radiation Activates AMP-Activated Kinase (AMPK): A Target for Radiosensitization of Human Cancer Cells

    SciTech Connect

    Sanli, Toran; Rashid, Ayesha; Liu Caiqiong

    2010-09-01

    Purpose: Adenosine monophosphate (AMP)-activated kinase (AMPK) is a molecular energy sensor regulated by the tumor suppressor LKB1. Starvation and growth factors activate AMPK through the DNA damage sensor ataxia-telangiectasia mutated (ATM). We explored the regulation of AMPK by ionizing radiation (IR) and its role as a target for radiosensitization of human cancer cells. Methods and Materials: Lung, prostate, and breast cancer cells were treated with IR (2-8 Gy) after incubation with either ATM or AMPK inhibitors or the AMPK activator metformin. Then, cells were subjected to either lysis and immunoblotting, immunofluorescence microscopy, clonogenic survival assays, or cell cycle analysis. Results: IR induced a robust phosphorylation and activation of AMPK in all tumor cells, independent of LKB1. IR activated AMPK first in the nucleus, and this extended later into cytoplasm. The ATM inhibitor KU-55933 blocked IR activation of AMPK. AMPK inhibition with Compound C or anti-AMPK {alpha} subunit small interfering RNA (siRNA) blocked IR induction of the cell cycle regulators p53 and p21{sup waf/cip} as well as the IR-induced G2/M arrest. Compound C caused resistance to IR, increasing the surviving fraction after 2 Gy, but the anti-diabetic drug metformin enhanced IR activation of AMPK and lowered the surviving fraction after 2 Gy further. Conclusions: We provide evidence that IR activates AMPK in human cancer cells in an LKB1-independent manner, leading to induction of p21{sup waf/cip} and regulation of the cell cycle and survival. AMPK appears to (1) participate in an ATM-AMPK-p21{sup waf/cip} pathway, (2) be involved in regulation of the IR-induced G2/M checkpoint, and (3) may be targeted by metformin to enhance IR responses.

  6. Novel Hsp90 inhibitor NVP-AUY922 radiosensitizes prostate cancer cells

    PubMed Central

    Gandhi, Nishant; Wild, Aaron T.; Chettiar, Sivarajan T.; Aziz, Khaled; Kato, Yoshinori; Gajula, Rajendra P.; Williams, Russell D.; Cades, Jessica A.; Annadanam, Anvesh; Song, Danny; Zhang, Yonggang; Hales, Russell K.; Herman, Joseph M.; Armour, Elwood; DeWeese, Theodore L.; Schaeffer, Edward M.; Tran, Phuoc T.

    2013-01-01

    Outcomes for poor-risk localized prostate cancers treated with radiation are still insufficient. Targeting the “non-oncogene” addiction or stress response machinery is an appealing strategy for cancer therapeutics. Heat-shock-protein-90 (Hsp90), an integral member of this machinery, is a molecular chaperone required for energy-driven stabilization and selective degradation of misfolded “client” proteins, that is commonly overexpressed in tumor cells. Hsp90 client proteins include critical components of pathways implicated in prostate cancer cell survival and radioresistance, such as androgen receptor signaling and the PI3K-Akt-mTOR pathway. We examined the effects of a novel non-geldanamycin Hsp90 inhibitor, AUY922, combined with radiation (RT) on two prostate cancer cell lines, Myc-CaP and PC3, using in vitro assays for clonogenic survival, apoptosis, cell cycle distribution, γ-H2AX foci kinetics and client protein expression in pathways important for prostate cancer survival and radioresistance. We then evaluated tumor growth delay and effects of the combined treatment (RT-AUY922) on the PI3K-Akt-mTOR and AR pathways in a hind-flank tumor graft model. We observed that AUY922 caused supra-additive radiosensitization in both cell lines at low nanomolar doses with enhancement ratios between 1.4–1.7 (p < 0.01). RT-AUY922 increased apoptotic cell death compared with either therapy alone, induced G2-M arrest and produced marked changes in client protein expression. These results were confirmed in vivo, where RT-AUY922 combination therapy produced supra-additive tumor growth delay compared with either therapy by itself in Myc-CaP and PC3 tumor grafts (both p < 0.0001). Our data suggest that combined RT-AUY922 therapy exhibits promising activity against prostate cancer cells, which should be investigated in clinical studies. PMID:23358469

  7. Radiosensitizing Effects of Ectopic miR-101 on Non-Small-Cell Lung Cancer Cells Depend on the Endogenous miR-101 Level

    SciTech Connect

    Chen, Susie; Wang Hongyan; Ng, Wooi Loon; Curran, Walter J.; Wang Ya

    2011-12-01

    Purpose: Previously, we showed that ectopic miR-101 could sensitize human tumor cells to radiation by targeting ATM and DNA-PK catalytic subunit (DNA-PKcs) to inhibit DNA repair, as the endogenous miR-101 levels are low in tumors in general. However, the heterogeneity of human cancers may result in an exception. The purpose of this study was to test the hypothesis that a few tumor cell lines with a high level of endogenous miR-101 would prove less response to ectopic miR-101. Methods and Materials: Fourteeen non-small-cell lung cancer (NSCLC) cell lines and one immortalized non-malignant lung epithelial cell line (NL20) were used for comparing endogenous miR-101 levels by real-time reverse transcription-polymerase chain reaction. Based on the different miR-101 levels, four cell lines with different miR-101 levels were chosen for transfection with a green fluorescent protein-lentiviral plasmid encoding miR-101. The target protein levels were measured by using Western blotting. The radiosensitizing effects of ectopic miR-101 on these NSCLC cell lines were determined by a clonogenic assay and xenograft mouse model. Results: The endogenous miR-101 level was similar or lower in 13 NSCLC cell lines but was 11-fold higher in one cell line (H157) than in NL20 cells. Although ectopic miR-101 efficiently decreased the ATM and DNA-PKcs levels and increased the radiosensitization level in H1299, H1975, and A549 cells, it did not change the levels of the miR-101 targets or radiosensitivity in H157 cells. Similar results were observed in xenograft mice. Conclusions: A small number of NSCLC cell lines could have a high level of endogenous miR-101. The ectopic miR-101 was able to radiosensitize most NSCLC cells, except for the NSCLC cell lines that had a much higher endogenous miR-101 level. These results suggest that when we choose one miRNA as a therapeutic tool, the endogenous level of the miRNA in each tumor should be considered.

  8. Rigosertib Is a More Effective Radiosensitizer Than Cisplatin in Concurrent Chemoradiation Treatment of Cervical Carcinoma, In Vitro and In Vivo

    SciTech Connect

    Agoni, Lorenzo; Basu, Indranil; Gupta, Seema; Alfieri, Alan; Gambino, Angela; Goldberg, Gary L.; Reddy, E. Premkumar; Guha, Chandan

    2014-04-01

    Purpose: To compare rigosertib versus cisplatin as an effective radiosensitizing agent for cervical malignancies. Methods and Materials: Rigosertib and cisplatin were tested in cervical cancer cell lines, HeLa and C33A. A 24-hour incubation with rigosertib and cisplatin, before irradiation (2-8 Gy), was used for clonogenic survival assays. Cell cycle analysis (propidium iodide staining) and DNA damage (γ-H2AX expression) were evaluated by fluorescence-activated cell sorter cytometry. Rigosertib was also tested in vivo in tumor growth experiments on cervical cancer xenografts. Results: Rigosertib was demonstrated to induce a G{sub 2}/M block in cancer cells. Survival curve comparison revealed a dose modification factor, as index of radiosensitization effect, of 1.1-1.3 for cisplatin and 1.4-2.2 for rigosertib. With 6-Gy irradiation, an increase in DNA damage of 15%-25% was achieved in both HeLa and C33A cells with cisplatin pretreatment, and a 71-108% increase with rigosertib pretreatment. In vivo tumor growth studies demonstrated higher performance of rigosertib when compared with cisplatin, with 53% longer tumor growth delay. Conclusions: Rigosertib was more effective than cisplatin when combined with radiation and caused minimal toxicity. These data support the need for clinical trials with rigosertib in combination therapy for patients with cervical carcinoma.

  9. DNA polymerase activity in heat killing and hyperthermic radiosensitization of mammalian cells as observed after fractionated heat treatments.

    PubMed

    Jorritsma, J B; Burgman, P; Kampinga, H H; Konings, A W

    1986-03-01

    Possible relations between hyperthermic inactivation of alpha and beta DNA polymerase activity and hyperthermic cell killing or hyperthermic radiosensitization were investigated. Ehrlich Ascites Tumor (EAT) cells and HeLa S3 cells were treated with fractionated doses of hyperthermia. The heating schedules were chosen such that the initial heat treatment resulted in either thermotolerance or thermosensitization (step-down heating) for the second heat treatment. The results show that for DNA polymerase activity and heat radiosensitization (cell survival) no thermotolerance or thermosensitization is observed. Thus hyperthermic cell killing and DNA polymerase activity are not correlated. The correlation of hyperthermic radiosensitization and DNA polymerase activity was substantially less than observed in previous experiments with normotolerant and thermotolerant HeLa S3 cells. We conclude that alpha and beta DNA polymerase inactivation is not always the critical cellular process responsible for hyperthermic cell killing or hyperthermic radiosensitization. Other possible cellular systems that might determine these processes are discussed. PMID:3754338

  10. Investigating micronucleus assay applicability for prediction of normal tissue intrinsic radiosensitivity in gynecological cancer patients

    PubMed Central

    Encheva, Elitsa; Deleva, Sofia; Hristova, Rositsa; Hadjidekova, Valeria; Hadjieva, Tatiana

    2011-01-01

    Background Pelvic organs morbidity after irradiation of cancer patients remains a major problem although new technologies have been developed and implemented. A relatively simple and suitable method for routine clinical practice is needed for preliminary assessment of normal tissue intrinsic radiosensitivity. The micronucleus test (MNT) determines the frequency of the radiation induced micronuclei (MN) in peripheral blood lymphocytes, which could serve as an indicator of intrinsic cell radiosensitivity. Aim To investigate a possible use of the micronucleus test (MNT) for acute radiation morbidity prediction in gynecological cancer patients. Materials and methods Forty gynecological cancer patients received 50 Gy conventional external pelvic irradiation after radical surgery. A four-field “box” technique was applied with 2D planning. The control group included 10 healthy females. Acute normal tissue reactions were graded according to NCI CTCAE v.3.0. From all reaction scores, the highest score named “summarized clinical radiosensitivity” was selected for a statistical analysis. MNT was performed before and after in vitro irradiation with 1.5 Gy. The mean radiation induced frequency of micronuclei per 1000 binucleated cells (MN/1000) and lymphocytes containing micronuclei per 1000 binucleated cells (cells with MN/1000) were evaluated for both patients and controls. An arbitrary cut off value was created to pick up a radiosensitive individual: the mean value of spontaneous frequency of cells with MN/1000 ± 2SD, found in the control group. Results Both mean spontaneous frequency of cells with MN/1000 and MN/1000 were registered to be significantly higher in cancer patients compared to the control group (t = 2.46, p = 0.02 and t = 2.51, p = 0.02). No statistical difference was registered when comparing radiation induced MN frequencies between those groups. Eighty percent (32) of patients developed grade 2 summarized clinical radiosensitivity, with

  11. Radiosensitivity of CD45RO{sup +} memory and CD45RO{sup {minus}} naive T cells in culture

    SciTech Connect

    Uzawa, Akiko; Suzuki, Gen; Nakata, Yukiko; Akashi, Makoto; Ohyama, Harumi; Akanuma, Atsuo

    1994-01-01

    Radiosensitivities of various human T-cell subsets were investigated by a proliferation assay and by a single-cell gel electrophoresis assay. Each T-cell subset was purified using a cell sorter and was induced to proliferate by ionomycin and interleukin 2. Unsorted T cells showed biphasic dose-survival curves, indicating the heterogeneity of T cells in terms of radiosensitivity. Purified CD4{sup +} helper and CD8{sup +} killer T cells showed similar biphasic dose-survival curves. Hence both T-cell subsets were composed of cells of different radiosensitivity. The T-cell subsets belonging to different activation stages such as CD45RO{sup +} memory and CD45RO{sup {minus}} naive T cells had different dose-survival curves. The former was more radiosensitive than the latter. The high radiosensitivity of CD45RO{sup +} cells was also demonstrated by single-cell gel electrophoresis after irradiation. This is the first demonstration that a particular cell surface marker on T cells is correlated with greater radiosensitivity. 27 refs., 7 figs., 1 tab.