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Sample records for c-myc protein expression

  1. Expression of heat shock protein 70 and c-myc in cervical carcinoma.

    PubMed

    Abd el All, H; Rey, A; Duvillard, P

    1998-01-01

    Heat shock protein 70 (hsp70), is a molecular chaperone that binds to c-myc and regulates its accumulation and localisation. In an attempt to confirm this association and to find out its prognostic significance in cervical carcinoma, paraffin embedded sections from 15 chronic cervicitis, 31 squamous cell carcinomas (scc) and 7 adenocarcinomas of the uterine cervix were immunohistochemically (IHC) stained for hsp70 and c-myc. hsp70 was faintly expressed cytoplasmically in non neoplastic squamous and endocervical epithelium, while mainly nuclear staining with variable intensities was seen in all scc and in squamous intraepithelial lesions (SIL) overlying 8 tumors. Both cytoplasmic and nuclear staining was noted in adenocarcinoma. c-myc was moderately expressed in the cytoplasm of all non neoplastic endocervical glands, while very mild cytoplasmic staining was noted in squamous epithelium. In SIL and in scc the staining intensity increased and was mainly nuclear. For adenocarcinoma, nuclear and cytoplasmic staining with different intensities was noted. There were significant positive correlations between the IHC expression of hsp70 and c-myc (p = 0.0001). In conclusion, our results confirm the co-association of c-myc and hsp70. This co-association might be a mechanism of tumor escape by preventing hsp70 binding to one of its normal target, the MHC class I, and preventing its subsequent expression on the surface of the cancerous cells. Lastly, the nuclear expression of hsp70 might be considered as an indicator of malignant transformation. PMID:9673366

  2. hTERT protein expression is independent of clinicopathological parameters and c-Myc protein expression in human breast cancer

    PubMed Central

    Elkak, AE; Meligonis, G; Salhab, M; Mitchell, B; Blake, JRS; Newbold, RF; Mokbel, K

    2005-01-01

    Background Telomerase is a ribonucleoprotein enzyme that synthesises telomeres after cell division and maintains chromosomal length and stability thus leading to cellular immortalisation. The hTERT (human telomerase reverse transcriptase) subunit seems to be the rate-limiting determinant of telomerase and knowledge of factors controlling hTERT transcription may be useful in therapeutic strategies. The hTERT promoter contains binding sites for c-Myc and there is some experimental and in vitro evidence that c-Myc may increase hTERT expression. We previously reported no correlation between c-Myc mRNA expression and hTERT mRNA or telomerase activity in human breast cancer. This study aims to examine the correlation between hTERT expression as determined by immunohistochemistry and c-Myc expression, lymph node status, and tumour size and grade in human breast cancer. Materials and methods The immunohistochemical expression of hTERT and c-Myc was investigated in 38 malignant breast tumours. The expression of hTERT was then correlated with the lymph node status, c-Myc expression and other clinicopathological parameters of the tumours. Results hTERT expression was positive in 27 (71%) of the 38 tumours. 15 (79%) of 19 node positive tumours were hTERT positive compared with 11 (63%) of 19 node negative tumours. The expression was higher in node positive tumours but this failed to reach statistical significance (p = 0.388). There was no significant association with tumour size, tumour grade or c-Myc expression. However, hTERT expression correlated positively with patients' age (correlation coefficient = 0.415, p = 0.0097). Conclusion hTERT protein expression is independent of lymph node status, tumour size and grade and c-Myc protein expression in human breast cancer PMID:16202165

  3. Acidosis decreases c-Myc oncogene expression in human lymphoma cells: a role for the proton-sensing G protein-coupled receptor TDAG8.

    PubMed

    Li, Zhigang; Dong, Lixue; Dean, Eric; Yang, Li V

    2013-01-01

    Acidosis is a biochemical hallmark of the tumor microenvironment. Here, we report that acute acidosis decreases c-Myc oncogene expression in U937 human lymphoma cells. The level of c-Myc transcripts, but not mRNA or protein stability, contributes to c-Myc protein reduction under acidosis. The pH-sensing receptor TDAG8 (GPR65) is involved in acidosis-induced c-Myc downregulation. TDAG8 is expressed in U937 lymphoma cells, and the overexpression or knockdown of TDAG8 further decreases or partially rescues c-Myc expression, respectively. Acidic pH alone is insufficient to reduce c-Myc expression, as it does not decrease c-Myc in H1299 lung cancer cells expressing very low levels of pH-sensing G protein-coupled receptors (GPCRs). Instead, c-Myc is slightly increased by acidosis in H1299 cells, but this increase is completely inhibited by ectopic overexpression of TDAG8. Interestingly, TDAG8 expression is decreased by more than 50% in human lymphoma samples in comparison to non-tumorous lymph nodes and spleens, suggesting a potential tumor suppressor function of TDAG8 in lymphoma. Collectively, our results identify a novel mechanism of c-Myc regulation by acidosis in the tumor microenvironment and indicate that modulation of TDAG8 and related pH-sensing receptor pathways may be exploited as a new approach to inhibit Myc expression. PMID:24152439

  4. Acidosis Decreases c-Myc Oncogene Expression in Human Lymphoma Cells: A Role for the Proton-Sensing G Protein-Coupled Receptor TDAG8

    PubMed Central

    Li, Zhigang; Dong, Lixue; Dean, Eric; Yang, Li V.

    2013-01-01

    Acidosis is a biochemical hallmark of the tumor microenvironment. Here, we report that acute acidosis decreases c-Myc oncogene expression in U937 human lymphoma cells. The level of c-Myc transcripts, but not mRNA or protein stability, contributes to c-Myc protein reduction under acidosis. The pH-sensing receptor TDAG8 (GPR65) is involved in acidosis-induced c-Myc downregulation. TDAG8 is expressed in U937 lymphoma cells, and the overexpression or knockdown of TDAG8 further decreases or partially rescues c-Myc expression, respectively. Acidic pH alone is insufficient to reduce c-Myc expression, as it does not decrease c-Myc in H1299 lung cancer cells expressing very low levels of pH-sensing G protein-coupled receptors (GPCRs). Instead, c-Myc is slightly increased by acidosis in H1299 cells, but this increase is completely inhibited by ectopic overexpression of TDAG8. Interestingly, TDAG8 expression is decreased by more than 50% in human lymphoma samples in comparison to non-tumorous lymph nodes and spleens, suggesting a potential tumor suppressor function of TDAG8 in lymphoma. Collectively, our results identify a novel mechanism of c-Myc regulation by acidosis in the tumor microenvironment and indicate that modulation of TDAG8 and related pH-sensing receptor pathways may be exploited as a new approach to inhibit Myc expression. PMID:24152439

  5. The c-MYC Protooncogene Expression in Cholesteatoma

    PubMed Central

    Palkó, Enikő; Póliska, Szilárd; Csákányi, Zsuzsanna; Katona, Gábor; Karosi, Tamás; Penyige, András; Sziklai, István

    2014-01-01

    Cholesteatoma is an epidermoid cyst, which is most frequently found in the middle ear. The matrix of cholesteatoma is histologically similar to the matrix of the epidermoid cyst of the skin (atheroma); their epithelium is characterized by hyperproliferation. The c-MYC protooncogene located on chromosome 8q24 encodes a transcription factor involved in the regulation of cell proliferation and differentiation. Previous studies have found aneuploidy of chromosome 8, copy number variation of c-MYC gene, and the presence of elevated level c-MYC protein in cholesteatoma. In this study we have compared the expression of c-MYC gene in samples taken from the matrix of 26 acquired cholesteatomas (15 children and 11 adults), 15 epidermoid cysts of the skin (atheromas; head and neck region) and 5 normal skin samples (retroauricular region) using RT-qPCR, providing the first precise measurement of the expression of c-MYC gene in cholesteatoma. We have found significantly elevated c-MYC gene expression in cholesteatoma compared to atheroma and to normal skin samples. There was no significant difference, however, in c-MYC gene expression between cholesteatoma samples of children and adults. The significant difference in c-MYC gene expression level in cholesteatoma compared to that of atheroma implies a more prominent hyperproliferative phenotype which may explain the clinical behavior typical of cholesteatoma. PMID:24683550

  6. Far upstream element-binding protein 1 (FUBP1) is a potential c-Myc regulator in esophageal squamous cell carcinoma (ESCC) and its expression promotes ESCC progression.

    PubMed

    Yang, Lei; Zhu, Jun-Ya; Zhang, Jian-Guo; Bao, Bo-Jun; Guan, Cheng-Qi; Yang, Xiao-Jing; Liu, Yan-Hua; Huang, Yue-Jiao; Ni, Run-Zhou; Ji, Li-Li

    2016-03-01

    The human far upstream element (FUSE) binding protein 1 (FUBP1) belongs to an ancient family which is required for proper regulation of the c-Myc proto-oncogene. Although c-Myc plays an important role in development of various carcinomas, the relevance of FUBP1 and their contribution to esophageal squamous cell carcinoma (ESCC) development remain unclear. In this study, we aimed to investigate the relationship between FUBP1 and c-Myc as well as their contribution to ESCC development. Western blot and immunohistochemical analyses were performed to evaluate FUBP1 expression. Coimmunoprecipitation analysis was performed to explore the correlation between FUBP1 and c-Myc in ESCC. In addition, the role of FUBP1 in ESCC proliferation was studied in ESCC cells through knocking FUBP1 down. The regulation of FUBP1 on proliferation was confirmed by Cell Counting Kit-8 (CCK-8) assay, flow cytometric assays, and clone formation assays. The expressions of FUBP1 and c-Myc were both upregulated in ESCC tissues. In addition to correlation between expression of FUBP1 and tumor grade, we also confirmed the correlation of FUBP1, c-Myc, and Ki-67 expression by twos. Moreover, upregulation of FUBP1 and c-Myc in ESCC was associated with poor survival. FUBP1 was confirmed to activate c-Myc in ESCC tissues and cells. FUBP1 was demonstrated to promote proliferation of ESCC cells. Moreover, downregulation of both FUBP1 and c-Myc was confirmed to inhibit proliferation of ESCC cells. Our results indicated that FUBP1 may potentially stimulate c-Myc expression in ESCC and its expression may promote ESCC progression. PMID:26490982

  7. Ribosomal protein S14 negatively regulates c-Myc activity.

    PubMed

    Zhou, Xiang; Hao, Qian; Liao, Jun-Ming; Liao, Peng; Lu, Hua

    2013-07-26

    The ribosomal gene RPS14 is associated with the cancer-prone 5q-syndrome, which is caused by an interstitial deletion of the long arm of human chromosome 5. Previously, we found that ribosomal protein S14 (RPS14) binds to and inactivates MDM2, consequently leading to p53-dependent cell-cycle arrest and growth inhibition. However, it remains elusive whether RPS14 regulates cell proliferation in a p53-independent manner. Here, we show that RPS14 interacts with the Myc homology box II (MBII) and the C-terminal basic helix-loop-helix leucine zipper (bHLH-LZ) domains of the oncoprotein c-Myc. Further, RPS14 inhibited c-Myc transcriptional activity by preventing the recruitment of c-Myc and its cofactor, TRRAP, to the target gene promoters, as thus suppressing c-Myc-induced cell proliferation. Also, siRNA-mediated RPS14 depletion elevated c-Myc transcriptional activity determined by its target gene, Nucleolin, expression. Interestingly, RPS14 depletion also resulted in the induction of c-Myc mRNA and subsequent protein levels. Consistent with this, RPS14 promoted c-Myc mRNA turnover through an Argonaute 2 (Ago2)- and microRNA-mediated pathway. Taken together, our study demonstrates that RPS14 negates c-Myc functions by directly inhibiting its transcriptional activity and mediating its mRNA degradation via miRNA. PMID:23775087

  8. Dual Targeting of Bromodomain and Extraterminal Domain Proteins, and WNT or MAPK Signaling, Inhibits c-MYC Expression and Proliferation of Colorectal Cancer Cells.

    PubMed

    Tögel, Lars; Nightingale, Rebecca; Chueh, Anderly C; Jayachandran, Aparna; Tran, Hoanh; Phesse, Toby; Wu, Rui; Sieber, Oliver M; Arango, Diego; Dhillon, Amardeep S; Dawson, Mark A; Diez-Dacal, Beatriz; Gahman, Timothy C; Filippakopoulos, Panagis; Shiau, Andrew K; Mariadason, John M

    2016-06-01

    Inhibitors of the bromodomain and extraterminal domain (BET) protein family attenuate the proliferation of several tumor cell lines. These effects are mediated, at least in part, through repression of c-MYC. In colorectal cancer, overexpression of c-MYC due to hyperactive WNT/β-catenin/TCF signaling is a key driver of tumor progression; however, effective strategies to target this oncogene remain elusive. Here, we investigated the effect of BET inhibitors (BETi) on colorectal cancer cell proliferation and c-MYC expression. Treatment of 20 colorectal cancer cell lines with the BETi JQ1 identified a subset of highly sensitive lines. JQ1 sensitivity was higher in cell lines with microsatellite instability but was not associated with the CpG island methylator phenotype, c-MYC expression or amplification status, BET protein expression, or mutation status of TP53, KRAS/BRAF, or PIK3CA/PTEN Conversely, JQ1 sensitivity correlated significantly with the magnitude of c-MYC mRNA and protein repression. JQ1-mediated c-MYC repression was not due to generalized attenuation of β-catenin/TCF-mediated transcription, as JQ1 had minimal effects on other β-catenin/TCF target genes or β-catenin/TCF reporter activity. BETi preferentially target super-enhancer-regulated genes, and a super-enhancer in c-MYC was recently identified in HCT116 cells to which BRD4 and effector transcription factors of the WNT/β-catenin/TCF and MEK/ERK pathways are recruited. Combined targeting of c-MYC with JQ1 and inhibitors of these pathways additively repressed c-MYC and proliferation of HCT116 cells. These findings demonstrate that BETi downregulate c-MYC expression and inhibit colorectal cancer cell proliferation and identify strategies for enhancing the effects of BETi on c-MYC repression by combinatorial targeting the c-MYC super-enhancer. Mol Cancer Ther; 15(6); 1217-26. ©2016 AACR. PMID:26983878

  9. Down-regulation of Thanatos-associated protein 11 by BCR-ABL promotes CML cell proliferation through c-Myc expression.

    PubMed

    Nakamura, Satoki; Yokota, Daisuke; Tan, Lin; Nagata, Yasuyuki; Takemura, Tomonari; Hirano, Isao; Shigeno, Kazuyuki; Shibata, Kiyoshi; Fujisawa, Shinya; Ohnishi, Kazunori

    2012-03-01

    Bcr-Abl activates various signaling pathways in chronic myelogenous leukemia (CML) cells. The proliferation of Bcr-Abl transformed cells is promoted by c-Myc through the activation of Akt, JAK2 and NF-κB. However, the mechanism by which c-Myc regulates CML cell proliferation is unclear. In our study, we investigated the role of Thanatos-associated protein 11 (THAP11), which inhibits c-Myc transcription, in CML cell lines and in hematopoietic progenitor cells derived from CML patients. The induction of THAP11 expression by Abl kinase inhibitors in CML cell lines and in CML-derived hematopoietic progenitor cells resulted in the suppression of c-Myc. In addition, over-expression of THAP11 inhibited CML cell proliferation. In colony forming cells derived from CML-aldehyde dehydrogenase (ALDH)(hi) /CD34(+) cells, treatment with Abl kinase inhibitors and siRNA depletion of Bcr-Abl induced THAP11 expression and reduced c-Myc expression, resulting in inhibited colony formation. Moreover, overexpression of THAP11 significantly decreased the colony numbers, and also inhibited the expression of c-myc target genes such as Cyclin D1, ODC and induced the expression of p21(Cip1) . The depletion of THAP11 inhibited JAK2 or STAT5 inactivation-mediated c-Myc reduction in ALDH(hi) /CD34(+) CML cells. Thus, the induced THAP11 might be one of transcriptional regulators of c-Myc expression in CML cell. Therefore, the induction of THAP11 has a potential possibility as a target for the inhibition of CML cell proliferation. PMID:21400515

  10. Translocation of a store of maternal cytoplasmic c-myc protein into nuclei during early development.

    PubMed Central

    Gusse, M; Ghysdael, J; Evan, G; Soussi, T; Méchali, M

    1989-01-01

    The c-myc proto-oncogene is expressed as a maternal protein during oogenesis in Xenopus laevis, namely, in nondividing cells. A delayed translation of c-myc mRNA accumulated in early oocytes results in the accumulation of the protein during late oogenesis. The oocyte c-myc protein is unusually stable and is located in the cytoplasm, contrasting with its features in somatic cells. A mature oocyte contains a maternal c-myc protein stockpile of 4 x 10(5) to 6 x 10(5) times the level in a somatic growing cell. This level of c-myc protein is preserved only during the cleavage stage of the embryo. Fertilization triggers its rapid migration into the nuclei of the cleaving embryo and a change in the phosphorylation state of the protein. The c-myc protein content per nucleus decreases exponentially during the cleavage stage until a stoichiometric titration by the embryonic nuclei is reached during a 0.5-h period at the midblastula stage. Most of the maternal c-myc store is degraded by the gastrula stage. These observations implicate the participation of c-myc in the events linked to early embryonic development and the midblastula transition. Images PMID:2685563

  11. Acetylation of the c-MYC oncoprotein is required for cooperation with the HTLV-1 p30{sup II} accessory protein and the induction of oncogenic cellular transformation by p30{sup II}/c-MYC

    SciTech Connect

    Romeo, Megan M.; Ko, Bookyung; Kim, Janice; Brady, Rebecca; Heatley, Hayley C.; He, Jeffrey; Harrod, Carolyn K.; Barnett, Braden; Ratner, Lee; Lairmore, Michael D.; Martinez, Ernest; Lüscher, Bernhard; Robson, Craig N.; Henriksson, Marie; Harrod, Robert

    2015-02-15

    The human T-cell leukemia retrovirus type-1 (HTLV-1) p30{sup II} protein is a multifunctional latency-maintenance factor that negatively regulates viral gene expression and deregulates host signaling pathways involved in aberrant T-cell growth and proliferation. We have previously demonstrated that p30{sup II} interacts with the c-MYC oncoprotein and enhances c-MYC-dependent transcriptional and oncogenic functions. However, the molecular and biochemical events that mediate the cooperation between p30{sup II} and c-MYC remain to be completely understood. Herein we demonstrate that p30{sup II} induces lysine-acetylation of the c-MYC oncoprotein. Acetylation-defective c-MYC Lys→Arg substitution mutants are impaired for oncogenic transformation with p30{sup II} in c-myc{sup −/−} HO15.19 fibroblasts. Using dual-chromatin-immunoprecipitations (dual-ChIPs), we further demonstrate that p30{sup II} is present in c-MYC-containing nucleoprotein complexes in HTLV-1-transformed HuT-102 T-lymphocytes. Moreover, p30{sup II} inhibits apoptosis in proliferating cells expressing c-MYC under conditions of genotoxic stress. These findings suggest that c-MYC-acetylation is required for the cooperation between p30{sup II}/c-MYC which could promote proviral replication and contribute to HTLV-1-induced carcinogenesis. - Highlights: • Acetylation of c-MYC is required for oncogenic transformation by HTLV-1 p30{sup II}/c-MYC. • Acetylation-defective c-MYC mutants are impaired for foci-formation by p30{sup II}/c-MYC. • The HTLV-1 p30{sup II} protein induces lysine-acetylation of c-MYC. • p30{sup II} is present in c-MYC nucleoprotein complexes in HTLV-1-transformed T-cells. • HTLV-1 p30{sup II} inhibits apoptosis in c-MYC-expressing proliferating cells.

  12. [PC-1 enhances c-myc gene expression in prostate cancer cells].

    PubMed

    Yu, Lan; Shi, Qing-Guo; Qian, Xiao-Long; Li, Shan-Hu; Wang, Hong-Tao; Wang, Le-Le; Zhou, Jian-Guang

    2010-04-01

    PC-1(Prostate and colon gene 1) gene belongs to TPD52 (Tumor Protein D52) gene family. The expression of PC-1 is found to promote androgen-independent progression. This study was conducted to assess the mechnism of promotion of androgen-independent progression in PC-1 gene. The c-myc gene expression was tested by RT-PCR and Western blotting analyses in the LNCaP-pc-1 and LNCaP-zero cell line. After separation of cytoplasm and nulear proteins of the LNCaP-pc-1 and LNCaP-zero cell line, the beta-catenin protein was detected by Western blotting. C4-2 cell line was used to examine the effects of 10058-F4 on the PC-1 gene expression. The results of RT-PCR and Western blotting indicated that PC-1 enhanced c-myc gene expression in prostate cancer cells, PC-1 was also found to enhance beta-catenin expression in nuclear. Furthermore, a small-molecule c-Myc inhibitor, 10058-F4 represses PC-1 gene expression in C4-2 cell line. Our findings suggest that PC-1 enhances c-myc gene expression in prostate cancer cells through the Wnt/beta-catenin pathway. Meanwhile, c-myc plays a feed-forward role in enhancing PC-1 driven c-myc gene expression, and promotes prostate an-drogen-independent progression. PMID:20423888

  13. Differential effects on ARF stability by normal vs. oncogenic levels of c-Myc expression

    PubMed Central

    Chen, Delin; Kon, Ning; Zhong, Jiayun; Zhang, Pingzhao; Yu, Long; Gu, Wei

    2013-01-01

    SUMMARY ARF suppresses aberrant cell growth upon c-Myc overexpression through activating p53 responses. Nevertheless, the precise mechanism by which ARF specifically, restrains the oncogenic potential of c-Myc without affecting its normal physiological function is not well understood. Here, we show that low levels of c-Myc expression stimulate cell proliferation whereas high levels inhibit through activating the ARF-p53 response. Although the mRNA levels of ARF are induced under both scenarios, the accumulation of ARF protein occurs only when ULF-mediated degradation of ARF is inhibited by c-Myc overexpression. Moreover, the levels of ARF are reduced through ULF-mediated ubiquitination upon DNA damage. Blocking ARF degradation by c-Myc overexpression dramatically stimulates the apoptotic responses. Our study reveals that ARF stability control is crucial for differentiating normal (low) vs. oncogenic (high) levels of c-Myc expression and suggests that differential effects on ULF- mediated ARF ubiquitination by c-Myc levels act as a barrier in oncogene-induced stress responses. PMID:23747016

  14. Synthesis of Fluorescent Binaphthyl Amines That Bind c-MYC G-Quadruplex DNA and Repress c-MYC Expression.

    PubMed

    Chauhan, Ajay; Paul, Rakesh; Debnath, Manish; Bessi, Irene; Mandal, Samir; Schwalbe, Harald; Dash, Jyotirmayee

    2016-08-11

    Two novel binaphthyl amines have been designed and synthesized using Buchwald amination and oxidative homocoupling as key steps. The binaphthyl amine containing two triazole rings shows higher affinity for c-MYC G-quadruplex, exhibits fluorescence "turn-on" response with c-MYC, and stains the nucleus in cells. The triazolyl binaphthyl amine shows cytotoxicity for cancer cells by inducing G2/M phase cell cycle arrest and apoptosis. Moreover, both ligands can downregulate c-MYC expression at transcriptional and translational levels. PMID:27442915

  15. Posttranscriptional regulation of cellular gene expression by the c-myc oncogene

    SciTech Connect

    Prendergast, G.C.; Cole, M.D. . Dept. of Biology)

    1989-01-01

    The c-myc oncogene has been implicated in the development of many different cancers, yet the mechanism by which the c-myc protein alters cellular growth control has proven elusive. The authors used a cDNA hybridization difference assay to isolate two genes, mr1 and mr2, that were constitutively expressed (i.e., deregulated) in rodent fibroblast cell lines immortalized by transfection of a viral promoter-linked c-myc gene. Both cDNAs were serum inducible in quiescent G/sub o/ fibroblasts, suggesting that they are functionally related to cellular proliferative processes. Although there were significant differences in cytoplasmic mRNA levels between myc-immortalized and control cells, the rates of transcription and mRNA turnover of both genes were similar, suggesting that c-myc regulates mr1 and mr2 expression by some nuclear posttranscriptional mechanism. Their results provide evidence that c-myc can rapidly modulate cellular gene expression and suggest that c-myc may function in gene regulation at the level of RNA export, splicing, or nuclear RNA turnover.

  16. Labdane type diterpenes down-regulate the expression of c-Myc protein, but not of Bcl-2, in human leukemia T-cells undergoing apoptosis.

    PubMed

    Dimas, K; Demetzos, C; Vaos, V; Ioannidis, P; Trangas, T

    2001-06-01

    Sclareol (1) and ent-3beta-hydroxy-13-epi-manoyl oxide (2) belong to the labdane type diterpenes. They were isolated from the leaves and from the fruits of Cistus creticus subsp. creticus, and were found to be active against human leukemic cell lines. Compound 2 was converted to its thiomidazolide derivative (3). Compounds 1 and 3 were found to induce apoptotic cell death in human T-cell leukemia lines and to interfere with their cell cycle, arresting cells at G(0/1) phase. Apoptosis can involve the activation and/or suppression of critical genes such as c-myc whose reduction or its inappropriate expression can be associated with induction of cell death and bcl-2 whose activation prevents apoptosis in the latter case. In order to detect any concomitant effect (1 and 3) upon c-myc and bcl-2 oncogene expression, we performed Western blot analysis to determine the levels of expression of these two genes upon treatment with the above compounds. Western blot analysis showed that of c-myc proto-oncogene levels were markedly reduced before massive apoptosis ensued in H33AJ-JA1 and MOLT3 cells, while bcl-2 expression remained unaffected. Thus, induction of apoptosis due to compounds 1 and 3 in these T-cell leukemic cell lines is preceded by c-myc down regulation and furthermore sustained bcl-2 expression does not rescue cells from apoptosis under the conditions used. PMID:11337016

  17. c-myc protooncogene expression in mouse erythroleukemia cells.

    PubMed Central

    Lachman, H M

    1989-01-01

    Murine erythroleukemia (MEL) cells are erythroid progenitors whose programs of erythroid differentiation has been interrupted by transformation with the Friend virus complex. As a result of the ability of certain chemicals such as dimethylsulfoxide (DMSO) to induce terminal erythroid differentiation, the cells have been used as a model for understanding the molecular basis of cellular differentiation. Recent work on MEL cells as well as other differentiating systems indicates that expression of cellular protooncogenes is implicated in chemically mediated differentiation. In MEL cells the expression of the c-myc protooncogene undergoes unusual biphasic changes following inducer treatment. Levels of c-myc mRNA decrease 10- to 20-fold between 1 and 2 hr and are then reexpressed between 12 and 24 hr. These changes occur as a result of complex transcriptional and posttranscriptional regulatory events. Recent DNA transfection experiments, in which MEL cells were transfected with myc expression vectors, indicate that both the early decrease in c-myc expression and its subsequent reexpression are important events in the differentiation pathway. The work on MEL cells, as well as on other models of differentiation, is directed at understanding the molecular basis of leukemogenic transformation and cellular differentiation. The ability of c-myc, as well as other protooncogenes, to influence both of these events indicates that cellular protooncogenes play a central role in their regulation. Images FIGURE 1. FIGURE 2. FIGURE 3. FIGURE 4. FIGURE 5. PMID:2647476

  18. C-myc can induce expression of G/sub 0//G/sub 1/ transition genes

    SciTech Connect

    Schweinfest, C.W.; Fujiwara, S.; Lau, L.F.; Papas, T.S.

    1988-08-01

    The human c-myc oncogene was linked to the heat shock-inducible Drosophila hsp70 promoter and used to stably transfect mouse BALB/c 3T3 cells. Heat shock of the transfectants at 42/sup 0/C followed by recovery at 37/sup 0/C resulted in the appearance of the human c-myc protein which was appropriately localized to the nuclear fraction. Two-dimensional analysis of the proteins of density-arrested cells which had been heat shock treated revealed the induction of eight protein species and the repression of five protein species. All of the induced and repressed proteins were nonabundant. cDNA clones corresponding to genes induced during the G/sub 0//G/sub 1/ transition were used as probes to assay for c-myc inducibility of these genes. Two anonymous sequences previously identified as serum inducible (3CH77 and 3CH92) were induced when c-myc was expressed. In response to serum stimulation, 3CH77 and 3CH92 were expressed before c-myc mRNA levels increased. However, in response to specific induction of c-myc by heat shock of serum arrested cells, 3CH77 and 3CH92 mRNA levels increased after the rise in c-myc mRNA. Therefore, the authors hypothesize that abnormal expression of c-myc can induce genes involved in the proliferative response.

  19. Normal Expression of a Rearranged and Mutated c-myc Oncogene after Transfection into Fibroblasts

    NASA Astrophysics Data System (ADS)

    Richman, Adam; Hayday, Adrian

    1989-10-01

    Expression of the c-myc oncogene is deregulated in a variety of malignancies. Rearrangement and mutation of the c-myc locus is a characteristic feature of human Burkitt's lymphoma. Whether deregulation is solely a result of mutation of c-myc or whether it is influenced by the transformed B cell context has not been determined. A translocated and mutated allele of c-myc was stably transfected into fibroblasts. The rearranged allele was expressed indistinguishably from a normal c-myc gene: it had serum-regulated expression, was transcribed with normal promoter preference, and was strongly attenuated. Thus mutations by themselves are insufficient to deregulate c-myc transcription.

  20. Acetylation of the c-MYC oncoprotein is required for cooperation with the HTLV-1 p30II accessory protein and the induction of oncogenic cellular transformation by p30II/c-MYC

    PubMed Central

    Romeo, Megan M.; Ko, Bookyung; Kim, Janice; Brady, Rebecca; Heatley, Hayley C.; He, Jeffrey; Harrod, Carolyn K.; Barnett, Braden; Ratner, Lee; Lairmore, Michael D.; Martinez, Ernest; Lüscher, Bernhard; Robson, Craig N.; Henriksson, Marie; Harrod, Robert

    2014-01-01

    The human T-cell leukemia retrovirus type-1 (HTLV-1) p30II protein is a multifunctional latency-maintenance factor that negatively regulates viral gene expression and deregulates host signaling pathways involved in aberrant T-cell growth and proliferation. We have previously demonstrated that p30II interacts with the c-MYC oncoprotein and enhances c-MYC-dependent transcriptional and oncogenic functions. However, the molecular and biochemical events that mediate the cooperation between p30II and c-MYC remain to be completely understood. Herein we demonstrate that p30II induces lysine-acetylation of the c-MYC oncoprotein. Acetylation-defective c-MYC Lys→Arg substitution mutants are impaired for oncogenic transformation with p30II in c-myc−/− HO15.19 fibroblasts. Using dual-chromatin-immunoprecipitations (dual-ChIPs), we further demonstrate that p30II is present in c-MYC-containing nucleoprotein complexes in HTLV-1-transformed HuT-102 T-lymphocytes. Moreover, p30II inhibits apoptosis in proliferating cells expressing c-MYC under conditions of genotoxic stress. These findings suggest that c-MYC-acetylation is required for the cooperation between p30II/c-MYC which could promote proviral replication and contribute to HTLV-1-induced carcinogenesis. PMID:25569455

  1. Cell growth suppression by thanatos-associated protein 11(THAP11) is mediated by transcriptional downregulation of c-Myc.

    PubMed

    Zhu, C-Y; Li, C-Y; Li, Y; Zhan, Y-Q; Li, Y-H; Xu, C-W; Xu, W-X; Sun, H B; Yang, X-M

    2009-03-01

    Thanatos-associated proteins (THAPs) are zinc-dependent, sequence-specific DNA-binding factors involved in cell proliferation, apoptosis, cell cycle, chromatin modification and transcriptional regulation. THAP11 is the most recently described member of this human protein family. In this study, we show that THAP11 is ubiquitously expressed in normal tissues and frequently downregulated in several human tumor tissues. Overexpression of THAP11 markedly inhibits growth of a number of different cells, including cancer cells and non-transformed cells. Silencing of THAP11 by RNA interference in HepG2 cells results in loss of cell growth repression. These results suggest that human THAP11 may be an endogenous physiologic regulator of cell proliferation. We also provide evidence that the function of THAP11 is mediated by its ability to repress transcription of c-Myc. Promoter reporter assays indicate a DNA binding-dependent c-Myc transcriptional repression. Chromatin immunoprecipitations and EMSA assay suggest that THAP11 directly binds to the c-Myc promoter. The findings that expression of c-Myc rescues significantly cells from THAP11-mediated cell growth suppression and that THAP11 expression only slightly inhibits c-Myc null fibroblasts cells growth reveal that THAP11 inhibits cell growth through downregulation of c-Myc expression. Taken together, these suggest that THAP11 functions as a cell growth suppressor by negatively regulating the expression of c-Myc. PMID:19008924

  2. Aspirin and salicylic acid decrease c-Myc expression in cancer cells: a potential role in chemoprevention.

    PubMed

    Ai, Guoqiang; Dachineni, Rakesh; Muley, Pratik; Tummala, Hemachand; Bhat, G Jayarama

    2016-02-01

    Epidemiological studies have demonstrated a significant correlation between regular aspirin use and reduced colon cancer incidence and mortality; however, the pathways by which it exerts its anti-cancer effects are still not fully explored. We hypothesized that aspirin's anti-cancer effect may occur through downregulation of c-Myc gene expression. Here, we demonstrate that aspirin and its primary metabolite, salicylic acid, decrease the c-Myc protein levels in human HCT-116 colon and in few other cancer cell lines. In total cell lysates, both drugs decreased the levels of c-Myc in a concentration-dependent fashion. Greater inhibition was observed in the nucleus than the cytoplasm, and immunofluorescence studies confirmed these observations. Pretreatment of cells with lactacystin, a proteasome inhibitor, partially prevented the downregulatory effect of both aspirin and salicylic acid, suggesting that 26S proteasomal pathway is involved. Both drugs failed to decrease exogenously expressed DDK-tagged c-Myc protein levels; however, under the same conditions, the endogenous c-Myc protein levels were downregulated. Northern blot analysis showed that both drugs caused a decrease in c-Myc mRNA levels in a concentration-dependent fashion. High-performance liquid chromatography (HPLC) analysis showed that aspirin taken up by cells was rapidly metabolized to salicylic acid, suggesting that aspirin's inhibitory effect on c-Myc may occur through formation of salicylic acid. Our result suggests that salicylic acid regulates c-Myc level at both transcriptional and post-transcription levels. Inhibition of c-Myc may represent an important pathway by which aspirin exerts its anti-cancer effect and decrease the occurrence of cancer in epithelial tissues. PMID:26314861

  3. Expression of c-myc gene in human ovary carcinoma cells treated with vanadate

    SciTech Connect

    Itkes, A.V.; Imamova, L.R.; Alexandrova, N.M.; Favorova, O.O.; Kisselev, L.L. )

    1990-05-01

    The widely accepted hypothesis of vanadate action on cells postulates that this ion inhibits protein phosphatase(s) that dephosphorylates protein phosphotyrosine residues. This inhibition causes tyrosine hyperphosphorylation of cell proteins followed by changes in physiological action of phosphoproteins resulting in stimulation of cell proliferation, expression of protooncogenes, and transient cell transformation. The authors have found that treatment of human ovary carcinoma (CaOv) cells with vanadate causes the increase in total protein phosphorylation from 1.5- to 2.0-fold whereas the ratio between phosphoserine, phosphothreonine, and phosphotyrosine content remains unchanged. At the same time, enhancement of c-myc gene expression (not c-fos) was observed. Hence, the increase in the ratio of phosphotyrosine to phosphoserine and phosphothreonine is not an obligatory intermediate stage before vanadate-dependent activation of c-myc expression.

  4. Linc-RoR promotes c-Myc expression through hnRNP I and AUF1.

    PubMed

    Huang, Jianguo; Zhang, Ali; Ho, Tsui-Ting; Zhang, Ziqiang; Zhou, Nanjiang; Ding, Xianfeng; Zhang, Xu; Xu, Min; Mo, Yin-Yuan

    2016-04-20

    Linc-RoR was originally identified to be a regulator for induced pluripotent stem cells in humans and it has also been implicated in tumorigenesis. However, the underlying mechanism of Linc-RoR-mediated gene expression in cancer is poorly understood. The present study demonstrates that Linc-RoR plays an oncogenic role in part through regulation of c-Myc expression. Linc-RoR knockout (KO) suppresses cell proliferation and tumor growth. In particular, Linc-RoR KO causes a significant decrease in c-Myc whereas re-expression of Linc-RoR in the KO cells restores the level of c-Myc. Mechanistically, Linc-RoR interacts with heterogeneous nuclear ribonucleoprotein (hnRNP) I and AU-rich element RNA-binding protein 1 (AUF1), respectively, with an opposite consequence to their interaction with c-Myc mRNA. While Linc-RoR is required for hnRNP I to bind to c-Myc mRNA, interaction of Linc-RoR with AUF1 inhibits AUF1 to bind to c-Myc mRNA. As a result, Linc-RoR may contribute to the increased stability of c-Myc mRNA. Although hnRNP I and AUF1 can interact with many RNA species and regulate their functions, with involvement of Linc-RoR they would be able to selectively regulate mRNA stability of specific genes such as c-Myc. Together, these results support a role for Linc-RoR in c-Myc expression in part by specifically enhancing its mRNA stability, leading to cell proliferation and tumorigenesis. PMID:26656491

  5. Linc-RoR promotes c-Myc expression through hnRNP I and AUF1

    PubMed Central

    Huang, Jianguo; Zhang, Ali; Ho, Tsui-Ting; Zhang, Ziqiang; Zhou, Nanjiang; Ding, Xianfeng; Zhang, Xu; Xu, Min; Mo, Yin-Yuan

    2016-01-01

    Linc-RoR was originally identified to be a regulator for induced pluripotent stem cells in humans and it has also been implicated in tumorigenesis. However, the underlying mechanism of Linc-RoR-mediated gene expression in cancer is poorly understood. The present study demonstrates that Linc-RoR plays an oncogenic role in part through regulation of c-Myc expression. Linc-RoR knockout (KO) suppresses cell proliferation and tumor growth. In particular, Linc-RoR KO causes a significant decrease in c-Myc whereas re-expression of Linc-RoR in the KO cells restores the level of c-Myc. Mechanistically, Linc-RoR interacts with heterogeneous nuclear ribonucleoprotein (hnRNP) I and AU-rich element RNA-binding protein 1 (AUF1), respectively, with an opposite consequence to their interaction with c-Myc mRNA. While Linc-RoR is required for hnRNP I to bind to c-Myc mRNA, interaction of Linc-RoR with AUF1 inhibits AUF1 to bind to c-Myc mRNA. As a result, Linc-RoR may contribute to the increased stability of c-Myc mRNA. Although hnRNP I and AUF1 can interact with many RNA species and regulate their functions, with involvement of Linc-RoR they would be able to selectively regulate mRNA stability of specific genes such as c-Myc. Together, these results support a role for Linc-RoR in c-Myc expression in part by specifically enhancing its mRNA stability, leading to cell proliferation and tumorigenesis. PMID:26656491

  6. Regulation of c-Myc expression by the histone demethylase JMJD1A is essential for prostate cancer cell growth and survival.

    PubMed

    Fan, L; Peng, G; Sahgal, N; Fazli, L; Gleave, M; Zhang, Y; Hussain, A; Qi, J

    2016-05-12

    The histone demethylase JMJD1A, which controls gene expression by epigenetic regulation of H3K9 methylation marks, functions in diverse activities, including spermatogenesis, metabolism and stem cell self-renewal and differentiation. Here, we found that JMJD1A knockdown in prostate cancer cells antagonizes their proliferation and survival. Profiling array analyses revealed that JMJD1A-dependent genes function in cellular growth, proliferation and survival, and implicated that the c-Myc transcriptional network is deregulated following JMJD1A inhibition. Biochemical analyses confirmed that JMJD1A enhances c-Myc transcriptional activity by upregulating c-Myc expression levels. Mechanistically, JMJD1A activity promoted recruitment of androgen receptor (AR) to the c-Myc gene enhancer and induced H3K9 demethylation, increasing AR-dependent transcription of c-Myc mRNA. In parallel, we found that JMJD1A regulated c-Myc stability, likely by inhibiting HUWE1, an E3 ubiquitin ligase known to target degradation of several substrates including c-Myc. JMJD1A (wild type or mutant lacking histone demethylase activity) bound to HUWE1, attenuated HUWE1-dependent ubiquitination and subsequent degradation of c-Myc, increasing c-Myc protein levels. Furthermore, c-Myc knockdown in prostate cancer cells phenocopied effects of JMJD1A knockdown, and c-Myc re-expression in JMJD1A-knockdown cells partially rescued prostate cancer cell growth in vitro and in vivo. c-Myc protein levels were positively correlated with those of JMJD1A in a subset of human prostate cancer specimens. Collectively, our findings identify a critical role for JMJD1A in regulating proliferation and survival of prostate cancer cells by controlling c-Myc expression at transcriptional and post-translational levels. PMID:26279298

  7. CTCF, a conserved nuclear factor required for optimal transcriptional activity of the chicken c-myc gene, is an 11-Zn-finger protein differentially expressed in multiple forms.

    PubMed Central

    Klenova, E M; Nicolas, R H; Paterson, H F; Carne, A F; Heath, C M; Goodwin, G H; Neiman, P E; Lobanenkov, V V

    1993-01-01

    A novel sequence-specific DNA-binding protein, CTCF, which interacts with the chicken c-myc gene promoter, has been identified and partially characterized (V. V. Lobanenkov, R. H. Nicolas, V. V. Adler, H. Paterson, E. M. Klenova, A. V. Polotskaja, and G. H. Goodwin, Oncogene 5:1743-1753, 1990). In order to test directly whether binding of CTCF to one specific DNA region of the c-myc promoter is important for chicken c-myc transcription, we have determined which nucleotides within this GC-rich region are responsible for recognition of overlapping sites by CTCF and Sp1-like proteins. Using missing-contact analysis of all four nucleotides in both DNA strands and homogeneous CTCF protein purified by sequence-specific chromatography, we have identified three sets of nucleotides which contact either CTCF or two Sp1-like proteins binding within the same DNA region. Specific mutations of 3 of 15 purines required for CTCF binding were designed to eliminate binding of CTCF without altering the binding of other proteins. Electrophoretic mobility shift assay of nuclear extracts showed that the mutant DNA sequence did not bind CTCF but did bind two Sp1-like proteins. When introduced into a 3.3-kbp-long 5'-flanking noncoding c-myc sequence fused to a reporter CAT gene, the same mutation of the CTCF binding site resulted in 10- and 3-fold reductions, respectively, of transcription in two different (erythroid and myeloid) stably transfected chicken cell lines. Isolation and analysis of the CTCF cDNA encoding an 82-kDa form of CTCF protein shows that DNA-binding domain of CTCF is composed of 11 Zn fingers: 10 are of C2H2 class, and 1 is of C2HC class. CTCF was found to be abundant and conserved in cells of vertebrate species. We detected six major nuclear forms of CTCF protein differentially expressed in different chicken cell lines and tissues. We conclude that isoforms of 11-Zn-finger factor CTCF which are present in chicken hematopoietic HD3 and BM2 cells can act as a positive

  8. PIWIL2 induces c-Myc expression by interacting with NME2 and regulates c-Myc-mediated tumor cell proliferation

    PubMed Central

    Zhang, Yu; Lu, Yilu; Chen, Jianhui; Zheng, Xulei; Tao, Dachang; Liu, Yunqiang; Ma, Yongxin

    2014-01-01

    c-Myc serves as a crucial regulator in multiple cellular events. Cumulative evidences demonstrate that anomalous c-Myc overexpression correlates with proliferation, invasion and metastasis in various human tumors. However, the transcriptionally activating mechanisms responsible for c-Myc overexpression are complex and continue to be intangible. Here we showed that Piwi-Like RNA-Mediated Gene Silencing 2 (PIWIL2) can upregulate c-Myc via binding with NME/NM23 nucleoside diphosphate kinase 2 (NME2). PIWIL2 promotes c-Myc transcription by interacting with and facilitating NME2 to bind to G4-motif region within c-Myc promoter. Interestingly, in a c-Myc-mediated manner, PIWIL2 upregulates RhoA, which in turn induces filamentary F-actin. Deficiency of PIWIL2 results in obstacle for c-Myc expression, cell cycle progress and cell proliferation. Taken together, our present work demonstrates that PIWIL2 modulates tumor cell proliferation and F-actin filaments via promoting c-Myc expression. PMID:25193865

  9. Runx transcription factors repress human and murine c-Myc expression in a DNA-binding and C-terminally dependent manner.

    PubMed

    Jacobs, Paejonette T; Cao, Li; Samon, Jeremy B; Kane, Christyne A; Hedblom, Emmett E; Bowcock, Anne; Telfer, Janice C

    2013-01-01

    The transcription factors Runx1 and c-Myc have individually been shown to regulate important gene targets as well as to collaborate in oncogenesis. However, it is unknown whether there is a regulatory relationship between the two genes. In this study, we investigated the transcriptional regulation of endogenous c-Myc by Runx1 in the human T cell line Jurkat and murine primary hematopoietic cells. Endogenous Runx1 binds to multiple sites in the c-Myc locus upstream of the c-Myc transcriptional start site. Cells transduced with a C-terminally truncated Runx1 (Runx1.d190), which lacks important cofactor interaction sites and can block C-terminal-dependent functions of all Runx transcription factors, showed increased transcription of c-Myc. In order to monitor c-Myc expression in response to early and transiently-acting Runx1.d190, we generated a cell membrane-permeable TAT-Runx1.d190 fusion protein. Murine splenocytes treated with TAT-Runx1.d190 showed an increase in the transcription of c-Myc within 2 hours, peaking at 4 hours post-treatment and declining thereafter. This effect is dependent on the ability of Runx1.d190 to bind to DNA. The increase in c-Myc transcripts is correlated with increased c-Myc protein levels. Collectively, these data show that Runx1 directly regulates c-Myc transcription in a C-terminal- and DNA-binding-dependent manner. PMID:23874874

  10. Runx Transcription Factors Repress Human and Murine c-Myc Expression in a DNA-Binding and C-Terminally Dependent Manner

    PubMed Central

    Jacobs, Paejonette T.; Cao, Li; Samon, Jeremy B.; Kane, Christyne A.; Hedblom, Emmett E.; Bowcock, Anne; Telfer, Janice C.

    2013-01-01

    The transcription factors Runx1 and c-Myc have individually been shown to regulate important gene targets as well as to collaborate in oncogenesis. However, it is unknown whether there is a regulatory relationship between the two genes. In this study, we investigated the transcriptional regulation of endogenous c-Myc by Runx1 in the human T cell line Jurkat and murine primary hematopoietic cells. Endogenous Runx1 binds to multiple sites in the c-Myc locus upstream of the c-Myc transcriptional start site. Cells transduced with a C-terminally truncated Runx1 (Runx1.d190), which lacks important cofactor interaction sites and can block C-terminal-dependent functions of all Runx transcription factors, showed increased transcription of c-Myc. In order to monitor c-Myc expression in response to early and transiently-acting Runx1.d190, we generated a cell membrane-permeable TAT-Runx1.d190 fusion protein. Murine splenocytes treated with TAT-Runx1.d190 showed an increase in the transcription of c-Myc within 2 hours, peaking at 4 hours post-treatment and declining thereafter. This effect is dependent on the ability of Runx1.d190 to bind to DNA. The increase in c-Myc transcripts is correlated with increased c-Myc protein levels. Collectively, these data show that Runx1 directly regulates c-Myc transcription in a C-terminal- and DNA-binding-dependent manner. PMID:23874874

  11. Discovery of a Family of Genomic Sequences Which Interact Specifically with the c-MYC Promoter to Regulate c-MYC Expression

    PubMed Central

    Thomas, Shelia D.; Rouchka, Eric C.; Miller, Donald M.

    2016-01-01

    G-quadruplex forming sequences are particularly enriched in the promoter regions of eukaryotic genes, especially of oncogenes. One of the most well studied G-quadruplex forming sequences is located in the nuclease hypersensitive element (NHE) III1 of the c-MYC promoter region. The oncoprotein c-MYC regulates a large array of genes which play important roles in growth regulation and metabolism. It is dysregulated in >70% of human cancers. The silencer NHEIII1 located upstream of the P1 promoter regulates up-to 80% of c-MYC transcription and includes a G-quadruplex structure (Pu27) that is required for promoter inhibition. We have identified, for the first time, a family of seventeen G-quadruplex-forming motifs with >90% identity with Pu27, located on different chromosomes throughout the human genome, some found near or within genes involved in stem cell maintenance or neural cell development. Notably, all members of the Pu27 family interact specifically with NHEIII1 sequence, in vitro. Crosslinking studies demonstrate that Pu27 oligonucleotide binds specifically to the C-rich strand of the NHEIII1 resulting in the G-quadruplex structure stabilization. Pu27 homologous sequences (Pu27-HS) significantly inhibit leukemic cell lines proliferation in culture. Exposure of U937 cells to the Pu27-HS induces cell growth inhibition associated with cell cycle arrest that is most likely due to downregulation of c-MYC expression at the RNA and/or protein levels. Expression of SOX2, another gene containing a Pu27-HS, was affected by Pu27-HS treatment as well. Our data suggest that the oligonucleotides encoding the Pu27 family target complementary DNA sequences in the genome, including those of the c-MYC and SOX2 promoters. This effect is most likely cell type and cell growth condition dependent. The presence of genomic G-quadruplex-forming sequences homologous to Pu27 of c-MYC silencer and the fact that they interact specifically with the parent sequence suggest a common

  12. Discovery of a Family of Genomic Sequences Which Interact Specifically with the c-MYC Promoter to Regulate c-MYC Expression.

    PubMed

    Rezzoug, Francine; Thomas, Shelia D; Rouchka, Eric C; Miller, Donald M

    2016-01-01

    G-quadruplex forming sequences are particularly enriched in the promoter regions of eukaryotic genes, especially of oncogenes. One of the most well studied G-quadruplex forming sequences is located in the nuclease hypersensitive element (NHE) III1 of the c-MYC promoter region. The oncoprotein c-MYC regulates a large array of genes which play important roles in growth regulation and metabolism. It is dysregulated in >70% of human cancers. The silencer NHEIII1 located upstream of the P1 promoter regulates up-to 80% of c-MYC transcription and includes a G-quadruplex structure (Pu27) that is required for promoter inhibition. We have identified, for the first time, a family of seventeen G-quadruplex-forming motifs with >90% identity with Pu27, located on different chromosomes throughout the human genome, some found near or within genes involved in stem cell maintenance or neural cell development. Notably, all members of the Pu27 family interact specifically with NHEIII1 sequence, in vitro. Crosslinking studies demonstrate that Pu27 oligonucleotide binds specifically to the C-rich strand of the NHEIII1 resulting in the G-quadruplex structure stabilization. Pu27 homologous sequences (Pu27-HS) significantly inhibit leukemic cell lines proliferation in culture. Exposure of U937 cells to the Pu27-HS induces cell growth inhibition associated with cell cycle arrest that is most likely due to downregulation of c-MYC expression at the RNA and/or protein levels. Expression of SOX2, another gene containing a Pu27-HS, was affected by Pu27-HS treatment as well. Our data suggest that the oligonucleotides encoding the Pu27 family target complementary DNA sequences in the genome, including those of the c-MYC and SOX2 promoters. This effect is most likely cell type and cell growth condition dependent. The presence of genomic G-quadruplex-forming sequences homologous to Pu27 of c-MYC silencer and the fact that they interact specifically with the parent sequence suggest a common

  13. Amplification and expression of the c-myc oncogene in human lung cancer cell lines.

    PubMed

    Little, C D; Nau, M M; Carney, D N; Gazdar, A F; Minna, J D

    Genetic changes involving the c-myc oncogene have been observed in human tumours. In particular, the c-myc gene is translocated in Burkitt's lymphoma and is amplified in the human promyelocytic leukaemia cell line, HL-60, which contains double minute chromosomes (DMs). More recently, an amplified c-myc gene has been positioned on a chromosomal homogeneous staining region (HSR) in a human colon cancer cell line, COLO 320, with neuroendocrine properties. Furthermore, c-myc is expressed in increased amounts in some human tumour lines, and in some cases, human small cell lung cancers (SCLC) contain DMs and HSRs. These findings prompted us to study the c-myc gene and its RNA expression in a series of human lung cancer cell lines. We now report amplification and expression of the c-myc oncogene in a system other than B-cell lymphomas, namely human lung cancer. Of 18 human lung cancer cell lines tested, 8 showed an amplified 12.5-kilobase (kb) EcoRI c-myc DNA band. Of particular interest are five SCLC lines with a high degree of c-myc DNA amplification (20-76-fold) and greatly increased levels of c-myc RNA. All five lines reside in the variant class of SCLC (SCLC-V) characterized by altered morphology, lack of expression of some SCLC-differentiated functions and more malignant behaviour than pure SCLC. Three of the five lines which have been karyotyped also contain DMs or HSRs. The finding of a greatly amplified c-myc gene in all cell lines of the SCLC-V class examined strongly suggests a role for the c-myc gene in the phenotypic conversion and malignant behaviour of human lung cancer. PMID:6646201

  14. Elevated c-myc protooncogene expression in autosomal recessive polycystic kidney disease

    SciTech Connect

    Cowley, B.D. Jr.; Smardo, F.L. Jr.; Grantham, J.J.; Calvet, J.P.

    1987-12-01

    The polycystic kidney diseases (PKDs) are a group of disorders characterized by the growth of epithelial cysts from the nephrons and collecting ducts of kidney tubules. The diseases can be inherited or can be provoked by environmental factors. To investigate the molecular basis of the abnormal cell growth associated with PKD, c-myc protooncogene expression was studied in a mouse model for autosomal recessive PKD. Homozygous recessive C57BL/6J (cpk/cpk) mice develop massively enlarged cystic kidneys and die from renal failure shortly after 3 weeks of age. Quantitative dot blot and RNA blot hybridization experiments in which whole kidney poly(A)/sup +/ RNA was hybridized with a c-myc RNA probe showed a 2- to 6-fold increase in c-myc mRNA at 2 weeks, and a 25- to 30-fold increase in c-myc mRNA at 3 weeks of age in polycystic mice, as compared to normal littermates. c-myc expression was also examined under two conditions in which kidney cell growth was experimentally induced in normal adult mice: compensatory renal hypertrophy and tubule regeneration following folic acid-induced renal cell injury. While compensatory hypertrophy resulted in only a small increase in c-myc, folic acid treatment gave rise after 24 hr to a 12-fold increase in c-myc RNA. The induction of c-myc by folic acid is consistent with increased cellular proliferation regenerating tubules. In contrast, polycystic kidneys show only a minimal increase in cellular proliferation over that seen in normal kidneys, while c-myc levels were found to be markedly elevated. Thus, the level of c-myc expression in cystic kidneys appears to be out of proportion to the rate of cell division, suggesting that elevated and potentially abnormal c-myc expression may be involved in the pathogenesis of PKD.

  15. SATB1 and SATB2 play opposing roles in c-Myc expression and progression of colorectal cancer.

    PubMed

    Mansour, Mohammed A; Hyodo, Toshinori; Akter, Khondker Ayesha; Kokuryo, Toshio; Uehara, Keisuke; Nagino, Masato; Senga, Takeshi

    2016-01-26

    Special AT-rich sequence-binding protein 1 and 2 (SATB1/2) are nuclear matrix-associated proteins involved in chromatin remodeling and regulation of gene expression. SATB2 acts as a tumor suppressor in laryngeal squamous cell carcinoma and colon cancer, whereas SATB1 promotes the progression of numerous types of cancers. In this study, we examined the effects of SATB1 and SATB2 on the malignant characteristics of colorectal cancer cells. SATB1 and SATB2 expression were negatively correlated in colorectal cancer specimens. SATB1 expression was increased, whereas SATB2 expression was reduced, in colorectal cancer tissues compared to control tissues. Exogenous expression of SATB2 in colorectal cancer cells suppressed cell proliferation, colony formation and tumor proliferation in mice. c-Myc was reduced by SATB2 expression, and exogenous expression of c-Myc in SATB2-expressing cells restored proliferation, colony formation and in vivo tumor growth of colorectal cancer cells. We also showed that c-Myc reduction by SATB2 was mediated by the inactivation of ERK5. In contrast, SATB1 promoted c-Myc expression. The expression of SATB1 in colorectal cancer tissues was positively correlated with c-Myc expression, and SATB1 knockdown reduced c-Myc expression in colorectal cancer cells. Finally, we showed that SATB1 knockdown in colorectal cancer cells suppressed cell proliferation, colony formation and cell invasion. Our results reveal interesting features of how the structural homologs SATB1 and SATB2 exert opposing functions in colorectal tumorigenesis. PMID:26701851

  16. SATB1 and SATB2 play opposing roles in c-Myc expression and progression of colorectal cancer

    PubMed Central

    Mansour, Mohammed A.; Hyodo, Toshinori; Akter, Khondker Ayesha; Kokuryo, Toshio; Uehara, Keisuke; Nagino, Masato; Senga, Takeshi

    2016-01-01

    Special AT-rich sequence-binding protein 1 and 2 (SATB1/2) are nuclear matrix-associated proteins involved in chromatin remodeling and regulation of gene expression. SATB2 acts as a tumor suppressor in laryngeal squamous cell carcinoma and colon cancer, whereas SATB1 promotes the progression of numerous types of cancers. In this study, we examined the effects of SATB1 and SATB2 on the malignant characteristics of colorectal cancer cells. SATB1 and SATB2 expression were negatively correlated in colorectal cancer specimens. SATB1 expression was increased, whereas SATB2 expression was reduced, in colorectal cancer tissues compared to control tissues. Exogenous expression of SATB2 in colorectal cancer cells suppressed cell proliferation, colony formation and tumor proliferation in mice. c-Myc was reduced by SATB2 expression, and exogenous expression of c-Myc in SATB2-expressing cells restored proliferation, colony formation and in vivo tumor growth of colorectal cancer cells. We also showed that c-Myc reduction by SATB2 was mediated by the inactivation of ERK5. In contrast, SATB1 promoted c-Myc expression. The expression of SATB1 in colorectal cancer tissues was positively correlated with c-Myc expression, and SATB1 knockdown reduced c-Myc expression in colorectal cancer cells. Finally, we showed that SATB1 knockdown in colorectal cancer cells suppressed cell proliferation, colony formation and cell invasion. Our results reveal interesting features of how the structural homologs SATB1 and SATB2 exert opposing functions in colorectal tumorigenesis. PMID:26701851

  17. c-myc and c-myb protein degradation: effect of metabolic inhibitors and heat shock.

    PubMed Central

    Lüscher, B; Eisenman, R N

    1988-01-01

    The proteins encoded by both viral and cellular forms of the c-myc oncogene have been previously demonstrated to have exceptionally short in vivo half-lives. In this paper we report a comparative study on the parameters affecting turnover of nuclear oncoproteins c-myc, c-myb, and the rapidly metabolized cytoplasmic enzyme ornithine decarboxylase. The degradation of all three proteins required metabolic energy, did not result in production of cleavage intermediates, and did not involve lysosomes or ubiquitin. A five- to eightfold increase in the half-life of c-myc proteins, and a twofold increase in the half-life of c-myb proteins was detected after heat-shock treatment at 46 degrees C. In contrast, heat shock had no effect on the turnover of ornithine decarboxylase. Heat shock also had the effect of increasing the rate of c-myc protein synthesis twofold, whereas c-myb protein synthesis was decreased nearly fourfold. The increased stability and synthesis of c-myc proteins led to an overall increase in the total level of c-myc proteins in response to heat-shock treatment. Furthermore, treatments which reduced c-myc and c-myb protein turnover, such as heat shock and exposure to inhibitors of metabolic energy production, resulted in reduced detergent solubility of both proteins. The recovery from heat shock, as measured by increased turnover and solubility, was energy dependent and considerably more rapid in thermotolerant cells. Images PMID:3043180

  18. c-Myc inhibits TP53INP1 expression via promoter methylation in esophageal carcinoma

    SciTech Connect

    Weng, Wenhao; Yang, Qinyuan; Huang, Miaolong; Qiao, Yongxia; Xie, Yuan; Yu, Yongchun; Jing, An; Li, Zhi

    2011-02-11

    Research highlights: {yields} TP53INP1 expression is down-regulated in esophageal carcinoma and is associated with CGI-131 methylation. {yields} Inhibition of CGI-131 methylation upregulates TP53INP1 expression in ESCC cell lines. {yields} Ectopic expression of TP53INP1 inhibits growth of ESCC cells by inducing apoptosis and inhibiting cell cycle progression. {yields} c-Myc binds to the promoter of TP53INP1 in vivo and vitro and recruits DNMT3A to TP53INP1 promoter for CGI-131 methylation. -- Abstract: Tumor protein p53-induced nuclear protein 1 (TP53INP1) is a well known stress-induced protein that plays a role in both cell cycle arrest and p53-mediated apoptosis. Loss of TP53INP1 expression has been reported in human melanoma, breast carcinoma, and gastric cancer. However, TP53INP1 expression and its regulatory mechanism in esophageal squamous cell carcinoma (ESCC) remain unclear. Our findings are in agreement with previous reports in that the expression of TP53INP1 was downregulated in 28% (10/36 cases) of ESCC lesions, and this was accompanied by significant promoter methylation. Overexpression of TP53INP1 induced G1 cell cycle arrest and increased apoptosis in ESCC cell lines (EC-1, EC-109, EC-9706). Furthermore, our study showed that the oncoprotein c-Myc bound to the core promoter of TP53INP1 and recruited DNA methyltransferase 3A to methylate the local promoter region, leading to the inhibition of TP53INP1 expression. Our findings revealed that TP53INP1 is a tumor suppressor in ESCC and that c-Myc-mediated DNA methylation-associated silencing of TP53INP1 contributed to the pathogenesis of human ESCC.

  19. Expression of c-myc and PCNA in Epstein-Barr virus-associated gastric carcinoma

    PubMed Central

    ZHU, SHIGUANG; SUN, PING; ZHANG, YINGXIN; YAN, LIPING; LUO, BING

    2013-01-01

    The aim of this study was to detect the expression of proliferatng cell nuclear antigen (PCNA) and c-myc in Epstein-Barr virus (EBV)-associated gastric carcinoma (EBVaGC) and EBV-negative gastric carcinoma (EBVnGC), as well as the expression of EBV-encoded proteins in EBVaGC and their effect on carcinogenesis and the development of gastric cancer. The PCNA and c-myc protein levels were assessed by immunohistochemistry in 13 EBVaGC and 45 EBVnGC specimens. The expression of related genes of EBV, including EB nuclear antigen (NA)-1 and EBNA2 genes, latent membrane protein 1 (LMP1) and early genes BARF1 and BHRF1 were tested by reverse transcription-polymerase chain reaction (RT-PCR) and southern blotting. The PCNA labeling index (LI) of EBVaGCs, EBVnGCs and the corresponding adjacent tissues of EBVaGCs were 49.3768±12.1832, 14.839±7.1847, 35.613±8.3831 and 24.2735±10.1332, respectively. The PCNA LI was significantly different between EBVaGC and EBVnGC of EBVaGC (t=4.686, P<0.01). The difference between EBVaGC and corresponding adjacent tissues of EBVaGC was also significant (t=8.805, P<0.01). The expression of c-myc protein was detected in 33 of 58 (55.39%) gastric carcinomas and in 21 of 58 (36.21%) adjacent tissues. There was a significant difference between the two groups (χ2=4.989, P<0.05). The expression of the c-myc protein was detected in 8 of 13 (61.54%) EBVaGCs and in 25 of 45 (55.56%) EBVnGCs. The difference between the two groups was not significant (χ2=0.147, P>0.05). EBNA1 mRNA was detected in all 13 EBVaGC cases, while EBNA2 and LMP1 mRNA was not detected in these cases. Of the 13 EBV-positive samples, 6 exhibited BARF1 transcripts and 2 exhibited BHRF1 transcripts. c-myc expression did not correlate with the presence of EBV in EBVaGC. EBV infection may induce PCNA expression. The lack of EBNA2 and LMP1 protein expression in EBVaGC suggests that EBNA2 and LMP1 do not correlate with cell apoptosis and c-myc expression. Early genes BARF1 and BHRF1

  20. Regulation of c-Myc protein stability by proteasome activator REGγ.

    PubMed

    Li, S; Jiang, C; Pan, J; Wang, X; Jin, J; Zhao, L; Pan, W; Liao, G; Cai, X; Li, X; Xiao, J; Jiang, J; Wang, P

    2015-06-01

    c-Myc is a key transcriptional factor that has a prominent role in cell growth, differentiation and tumor development. Its protein levels are tightly controlled by ubiquitin-proteasome pathway and frequently deregulated in various cancers. Here, we report that the 11S proteasomal activator REGγ is a novel regulator of c-Myc abundance in cells. We showed that overexpression of wild-type REGγ, but not inactive mutants including N151Y and G250S, significantly promoted the degradation of c-Myc. Depletion of REGγ markedly increased the protein stability of c-Myc. REGγ interacts with the C-terminal region of c-Myc and regulates c-Myc protein turnover. Functionally, REGγ negatively regulates c-Myc-mediated cell proliferation. Interestingly, depletion of the Drosophila Reg homolog (dReg) in developing wings induced the upregulation of Drosophila Myc, which contributes to cell death. Collectively, these results suggest that REGγ proteasome has a conserved role in the regulation of Myc abundance in both mammalian cells and Drosophila. PMID:25412630

  1. Expression of c-myc and mutation of the KRAS gene in patients with ovarian mucinous tumors.

    PubMed

    Li, X S; Sun, J; He, X L

    2015-01-01

    We examined the expression of c-myc and mutations in the KRAS gene in ovarian mucinous tumors to explore the pathogenesis of these tumors and the feasibility of targeted gene therapy. Expression of c-myc protein and mutations in the KRAS gene in 24 cases of ovarian mucinous cystadenoma, 46 cases of ovarian borderline mucinous cystadenoma, and 46 cases of ovarian mucinous cystadenocarcinoma were detected using the immunohistochemistry PV-9000 2-step method and polymerase chain reaction-restriction fragment length polymorphism. The positive expression rates of c-myc in ovarian mucinous cystadenoma, borderline mucinous cystadenoma, and cystadenocarcinoma were 0, 39.1, and 65.2%, respectively (P < 0.01), while the mutation rates in KRAS were 0, 39.1 and 13.0%, respectively. The mutation rate of the borderline group was significantly higher, while rates in the other 2 groups were similar (P > 0.05). c-myc was not correlated with clinical stage, pathological grade, or age of patients with ovarian mucinous cystadenocarcinoma or borderline mucinous cystadenoma (P > 0.05), but was correlated with tumor size (P < 0.05). Mutations in KRAS were not correlated with clinical stage or tumor size in patients with borderline mucinous cystadenoma (P > 0.05), whereas it was correlated with age (P < 0.05). In borderline mucinous cystadenoma, c-myc expression and KRAS mutations were not correlated (P > 0.05). c-myc is involved in the formation of ovarian borderline mucinous cystadenoma and mucinous cystadenocarcinoma, and the KRAS gene may contribute to the formation of borderline mucinous cystadenoma. PMID:26400304

  2. MHC class I expression in HPV 16 positive cervical carcinomas is post-transcriptionally controlled and independent from c-myc overexpression.

    PubMed

    Cromme, F V; Snijders, P J; van den Brule, A J; Kenemans, P; Meijer, C J; Walboomers, J M

    1993-11-01

    Squamous cell carcinomas of the uterine cervix (n = 23) were selected for the presence of human papillomavirus type 16 (HPV 16) using the polymerase chain reaction (PCR). Localization of transcripts coding for the E7 protein was demonstrated in neoplastic cells with RNA in situ hybridization. Consecutive tissue sections were investigated for expression of the major histocompatibility complex class I (MHC-I) and c-myc using immunohistochemical double staining procedures, since a role has been suggested for the c-myc protein in MHC-I down-regulation and c-myc overexpression has been described in cervical carcinomas. Reduced expression of class I heavy chains was observed in neoplastic cells from 18 out of 23 carcinomas (78%). Varying levels of c-myc overexpression were observed in 12 carcinomas (52%), from which four showed positive MHC-I expression in c-myc overexpressing cells. In the remaining eight c-myc overexpressing carcinomas MHC-I down-regulation was observed. Additional RNA in situ hybridization with class I heavy chain locus-specific RNA-probes revealed presence of class I mRNAs in those neoplastic cells that show negative staining for MHC-I protein. These data strongly indicate that MHC-I down-regulation in cervical carcinomas involves post-transcriptional mechanisms, not directly related to E7 transcription and overexpression of c-myc. PMID:8414499

  3. Amino-terminal domains of c-myc and N-myc proteins mediate binding to the retinoblastoma gene product

    NASA Astrophysics Data System (ADS)

    Rustgi, Anil K.; Dyson, Nicholas; Bernards, Rene

    1991-08-01

    THE proteins encoded by the myc gene family are involved in the control of cell proliferation and differentiation, and aberrant expression of myc proteins has been implicated in the genesis of a variety of neoplasms1. In the carboxyl terminus, myc proteins have two domains that encode a basic domain/helix-loop-helix and a leucine zipper motif, respectively. These motifs are involved both in DNA binding and in protein dimerization2-5. In addition, myc protein family members share several regions of highly conserved amino acids in their amino termini that are essential for transformation6,7. We report here that an N-terminal domain present in both the c-myc and N-myc proteins mediates binding to the retinoblastoma gene product, pRb. We show that the human papilloma virus E7 protein competes with c-myc for binding to pRb, indicating that these proteins share overlapping binding sites on pRb. Furthermore, a mutant Rb protein from a human tumour cell line that carried a 35-amino-acid deletion in its C terminus failed to bind to c-myc. Our results suggest that c-myc and pRb cooperate through direct binding to control cell proliferation.

  4. Constitutive expression of ectopic c-Myc delays glucocorticoid-evoked apoptosis of human leukemic CEM-C7 cells

    PubMed Central

    Medh, Rheem D; Wang, Aixia; Zhou, Feng; Thompson, E Brad

    2009-01-01

    Sensitivity to glucocorticoid (GC)-evoked apoptosis in lymphoid cell lines correlates closely with GC-mediated suppression of c-Myc expression. To establish a functional role for c-Myc in GC-mediated apoptosis, we have stably expressed MycER™, the human c-Myc protein fused to the modified ligand-binding domain of the murine estrogen receptor α, in GC-sensitive CEM-C7-14 cells. In CEM-C7-14 cells, MycER™ constitutively imparts c-Myc functions. Cells expressing MycER™ (C7-MycER™) exhibited a marked reduction in cell death after 72 h in 100 nM dexamethasone (Dex), with 10 – 20-fold more viable cells when compared to the parental CEM-C7-14 clone. General GC responsiveness was not compromised, as evidenced by Dex-mediated suppression of endogenous c-Myc and cyclin D3, and induction of c-Jun and the glucocorticoid receptor. MycER™ also blunted Dex-mediated upregulation of p27kip1 and suppression of the Myc target p53. In comparison to parental CEM-C7-14 cells, Dex-evoked DNA strand breaks were negligible and caspase activation was delayed, but the extent of G1 cell cycle arrest was similar in C7-MycER™ cells. Myc-ER™ did not result in permanent, complete resistance to GC however, and the GC-treated cells eventually died, indicative of redundant or interactive mechanisms in the GC-evoked lytic response of lymphoid cells. Our results emphasize the importance of c-Myc suppression in GC-evoked apoptosis of CEM-C7-14 cells. PMID:11498786

  5. Nuclear C-MYC expression level is associated with disease progression and potentially predictive of two year overall survival in prostate cancer

    PubMed Central

    Zeng, Wen; Sun, Hanying; Meng, Fankai; Liu, Zeming; Xiong, Jing; Zhou, Sheng; Li, Fan; Hu, Jia; Hu, Zhiquan; Liu, Zheng

    2015-01-01

    Purpose: Upregulation of nuclear C-MYC protein has been reported to be an early event in prostate cancer (PCa); however, its clinicopathological and prognostic significance remain controversial. We determined the association of nuclear C-MYC protein expression with clinicopathological parameters, prognosis, ETS-related gene (ERG) expression, and TMPRSS2-ERG status in PCa. Methods: Nuclear C-MYC and ERG expression by immunohistochemistry and TMPRSS2-ERG status by triple-color probe fluorescence in situ hybridization assay were determined in 50 hormone-naïve PCa patients and 31 radical prostatectomy specimens. Results: Nuclear C-MYC immunostaining was negative, positive, and strong positive in 27.5%, 32.5%, and 40.0% of cases, respectively. C-MYC immunostaining was significantly associated with clinical T stage (P < 0.001), distant metastasis at the time of diagnosis (P < 0.001) and TMPRSS2-ERG status (P = 0.001) but not with ERG immunostaining (P = 0.818). In the Kaplan-Meier analysis, C-MYC positive cases were found to have worse 2-year OS compared with C-MYC negative cases (P = 0.027). However, in the univariate Cox analysis, only TMPRSS2-ERG status (hazard ratio [HR] 0.189, 95% CI 0.057-0.629; P = 0.007) and distant metastasis (HR 3.545, 95% CI 1.056-11.894; P = 0.040) were significantly associated with 2-year OS. After adjusting for these two factors, TMPRSS2-ERG status still impacted 2-year OS (HR 0.196, 95% CI 0.049-0.778; P = 0.020). Conclusions: Nuclear C-MYC overexpression may be associated with disease progression and potentially predictive of 2-year OS in PCa. This is the first study to demonstrate an association between nuclear C-MYC immunostaining and TMPRSS2-ERG status in PCa. PMID:25973080

  6. β2-adrenergic receptor signaling promotes pancreatic ductal adenocarcinoma (PDAC) progression through facilitating PCBP2-dependent c-myc expression.

    PubMed

    Wan, Chunhua; Gong, Chen; Zhang, Haifeng; Hua, Lu; Li, Xiaohong; Chen, Xudong; Chen, Yinji; Ding, Xiaoling; He, Song; Cao, Wei; Wang, Yingying; Fan, Shaoqing; Xiao, Ying; Zhou, Guoxiong; Shen, Aiguo

    2016-04-01

    The β2-adrenergic receptor (β2-AR) plays a crucial role in pancreatic ductal adenocarcinoma (PDAC) progression. In this report, we identified poly(rC)-binding protein 2 (PCBP2) as a novel binding partner for β2-AR using immunoprecipitation-mass spectrometry (IP-MS) approach. The association between β2-AR and PCBP2 was verified using reciprocal immunoprecipitation. Importantly, we found significant interaction and co-localization of the two proteins in the presence of β2-AR agonist in Panc-1 and Bxpc3 PDAC cells. β2-AR-induced recruitment of PCBP2 led to augmented protein level of c-myc in PDAC cells, likely as a result of enhanced internal ribosome entry segment (IRES)-mediated translation of c-myc. The activation of β2-AR accelerated cell proliferation and colony formation, while knockdown of PCBP2 or c-myc restrained the effect. Furthermore, overexpression of PCBP2 was observed in human PDAC cell lines and tissue specimens compared to the normal pancreatic ductal epithelial cells and the non-cancerous tissues respectively. Overexpression of β2-AR and PCBP2 was associated with advanced tumor stage and significantly worsened prognosis in patients with PDAC. Our results elucidate a new molecular mechanism by which β2-AR signaling facilitates PDAC progression through triggering PCBP2-dependent c-myc expression. PMID:26803058

  7. c-Myc-mediated expression of nucleophosmin/B23 decreases during retinoic acid-induced differentiation of human leukemia HL-60 cells.

    PubMed

    Yung, Benjamin Y M

    2004-12-17

    The retinoic acid-induced differentiation of human leukemia HL-60 cells towards mature granulocytic cells was accompanied by the decline in the protein levels of c-myc, nucleophosmin/B23 and its promoter activity. These RA-induced effects were further enhanced by the concurrent treatment of HL-60 cells with p38 map kinase inhibitor SB203580 (SB). It seems that there is a strong correlation of nucleophosmin/B23 and c-Myc expressions in cells under RA treatment. Furthermore, nucleophosmin/B23 promoter activity decreased upon c-Myc antisense-mediated reduction of intracellular amount of c-Myc. CHIP assays showed that binding of c-Myc to the nucleophosmin/B23 promoter decreased in RA-treated cells. Thus, nucleophosmin/B23 expression is targeted by c-Myc during RA-induced differentiation. These results provide evidence for a novel mechanism of transcriptional downregulation of nucleophosmin/B23 and the functional role of c-Myc in RA-induced differentiation. PMID:15589822

  8. Use of a transfected and amplified Drosophila heat shock promoter construction for inducible production of toxic mouse c-myc proteins in CHO cells

    SciTech Connect

    Wurm, F.M.; Gwinn, K.A.; Papoulas, O.; Pallavicini, M.; Kingston, R.E.

    1987-07-24

    After transfection and selection with methotrexate, CHO cell lines were established which contained up to 2000 copies of an expression vector for c-myc protein. The vector contained the Drosophila heat shock protein 70 (hsp70) promoter fused with the coding region of the mouse c-myc gene. Incubation of cells for up to 3 hours at 43/sup 0/C resulted in at least a 100-fold induction of recombinant c-myc mRNA. When cells were shifted back to 37/sup 0/C, within 1 to 4 hours, this RNA was translated into protein to yield about 250 ..mu..g per 10/sup 9/ cells. Cells died a few hours later, suggesting that high concentrations of intracellular c-myc are cytotoxic. 47 refs., 5 figs.

  9. c-Myc is a universal amplifier of expressed genes in lymphocytes and embryonic stem cells

    PubMed Central

    Nie, Zuqin; Hu, Gangqing; Wei, Gang; Cui, Kairong; Yamane, Arito; Resch, Wolfgang; Wang, Ruoning; Green, Douglas R.; Tessarollo, Lino; Casellas, Rafael; Zhao, Keji; Levens, David

    2012-01-01

    Summary The c-Myc HLH-bZIP protein has been implicated in physiological or pathological growth, proliferation, apoptosis, metabolism and differentiation at the cellular, tissue or organismal levels via regulation of numerous target genes. No principle yet unifies Myc action due partly to an incomplete inventory and functional accounting of Myc’s targets. To observe Myc target expression and function in a system where Myc is temporally and physiologically regulated, the transcriptomes and the genome-wide distributions of Myc, RNA polymerase II and chromatin modifications were compared during lymphocyte activation and in ES cells as well. A remarkably simple rule emerged from this quantitative analysis: Myc is not an on-off specifier of gene activity, but is a non-linear amplifier of expression, acting universally at active genes, except for immediate early genes that are strongly induced before Myc. This rule of Myc action explains the vast majority of Myc biology observed in literature. PMID:23021216

  10. Overexpression of c-myc in diabetic mice restores altered expression of the transcription factor genes that regulate liver metabolism.

    PubMed Central

    Riu, Efren; Ferre, Tura; Mas, Alex; Hidalgo, Antonio; Franckhauser, Sylvie; Bosch, Fatima

    2002-01-01

    Overexpression of the c-Myc transcription factor in liver induces glucose uptake and utilization. Here we examined the effects of c- myc overexpression on the expression of hepatocyte-specific transcription factor genes which regulate the expression of genes controlling hepatic metabolism. At 4 months after streptozotocin (STZ) treatment, most diabetic control mice were highly hyperglycaemic and died, whereas in STZ-treated transgenic mice hyperglycaemia was markedly lower, the serum levels of beta-hydroxybutyrate, triacylglycerols and non-esterified fatty acids were normal, and they had greater viability in the absence of insulin. Furthermore, long-term STZ-treated transgenic mice showed similar glucose utilization and storage to healthy controls. This was consistent with the expression of glycolytic genes becoming normalized. In addition, restoration of gene expression of the transcription factor, sterol receptor element binding protein 1c, was observed in the livers of these transgenic mice. Further, in STZ-treated transgenic mice the expression of genes involved in the control of gluconeogenesis (phosphoenolpyruvate carbokykinase), ketogenesis (3-hydroxy-3-methylglutaryl-CoA synthase) and energy metabolism (uncoupling protein 2) had returned to normal. These findings were correlated with decreased expression of genes encoding the transcription factors hepatocyte nuclear factor 3gamma, peroxisome proliferator-activated receptor alpha and retinoid X receptor. These results indicate that c- myc overexpression may counteract diabetic changes by controlling hepatic glucose metabolism, both directly by altering the expression of metabolic genes and through the expression of key transcription factor genes. PMID:12230428

  11. Targeting a ribonucleoprotein complex containing the caprin-1 protein and the c-Myc mRNA suppresses tumor growth in mice: an identification of a novel oncotarget

    PubMed Central

    Qiu, Ya-Qi; Yang, Cheng-Wei; Lee, Yue-Zhi; Yang, Ruey-Bing; Lee, Chih-Hao; Hsu, Hsing-Yu; Chang, Chien-Chung; Lee, Shiow-Ju

    2015-01-01

    Tylophorine compounds have been the focus of drug development for decades. Tylophorine derivatives exhibit anti-cancer activities but their cellular targets remain unknown. We used a biotinylated tylophorine derivative to probe for the interacting cellular target(s) of tylophorine. Tylophorine directly binds to caprin-1 and consequently enhances the recruitment of G3BP1, c-Myc mRNA, and cyclin D2 mRNA to form a ribonucleoprotein complex. Subsequently, this tylophorine targeted ribonucleoprotein complex is sequestered to the polysomal fractions and the protein expressions of the associated mRNA-transcripts are repressed. Caprin-1 depleted carcinoma cells become more resistant to tylophorine, associated with decreased formation of the ribonucleoprotein complex targeted by tylophorine. Consequently, tylophorine downregulates c-Myc and cyclins D1/D2, causing hypophosphorylation of Rb and suppression of both processing-body formation and the Warburg effect. Gene expression profiling and gain-of-c-Myc-function experiments also revealed that the downregulated c-Myc contributes to the anti-oncogenic effects of tylophorine compounds. Furthermore, the potent tylophorine derivative dibenzoquinoline-33b elicited a similar effect, as c-Myc protein levels were also decreased in xenograft tumors treated with dibenzoquinoline-33b. Thus, tylophorine compounds exert anti-cancer activity predominantly by targeting and sequestering the caprin-1 protein and c-Myc mRNA associated ribonucleoprotein complex. PMID:25669982

  12. Expression of merlin, NDRG2, ERBB2, and c-MYC in meningiomas: relationship with tumor grade and recurrence

    PubMed Central

    Ongaratti, B.R.; Silva, C.B.O.; Trott, G.; Haag, T.; Leães, C.G.S.; Ferreira, N.P.; Oliveira, M.C.; Pereira-Lima, J.F.S.

    2016-01-01

    Meningiomas are common, usually benign tumors of the central nervous system that have a high rate of post-surgical recurrence or regrowth. We determined expression of the proteins merlin, NDRG2, ERBB2, and c-MYC in meningiomas using immunohistochemistry and assessed relationships between protein expression and gender, age, tumor grade, and recurrence or regrowth. The study sample comprised 60 patients, (44 women and 16 men) with a mean age of 53.2±12.7 years. Tumors were classified as grade I (n=48) or grades II and III (n=12). Expression of merlin, NDRG2, ERBB2, and c-MYC was not significantly different statistically with relation to gender, age, or meningioma recurrence or regrowth. Merlin was expressed in 100% of the cases. No statistically significant difference between tumor grade and recurrence or regrowth was identified. Statistically significant differences were identified between the mean age of patients with grade I (54.83±11.60) and grades II and III (46.58±15.08) meningiomas (P=0.043), between strong c-MYC expression and grades II and III (P<0.001), and between partial surgical resection and tumor recurrence or regrowth (P<0.001). These findings reveal the lower mean age among grades II and III meningioma patients than grade I patients, the influence of the protein merlin on tumorigenesis, the association of c-MYC with aggressive meningiomas, and that partial surgical resection is associated with tumor recurrence or regrowth. PMID:27007654

  13. LncRNA-MIF, a c-Myc-activated long non-coding RNA, suppresses glycolysis by promoting Fbxw7-mediated c-Myc degradation.

    PubMed

    Zhang, Pengfei; Cao, Limian; Fan, Pingsheng; Mei, Yide; Wu, Mian

    2016-08-01

    The c-Myc proto-oncogene is activated in more than half of all human cancers. However, the precise regulation of c-Myc protein stability is unknown. Here, we show that the lncRNA-MIF (c-Myc inhibitory factor), a c-Myc-induced long non-coding RNA, is a competing endogenous RNA for miR-586 and attenuates the inhibitory effect of miR-586 on Fbxw7, an E3 ligase for c-Myc, leading to increased Fbxw7 expression and subsequent c-Myc degradation. Our data reveal the existence of a feedback loop between c-Myc and lncRNA-MIF, through which c-Myc protein stability is finely controlled. Additionally, we show that the lncRNA-MIF inhibits aerobic glycolysis and tumorigenesis by suppressing c-Myc and miR-586. PMID:27317567

  14. Primary structure and functional scFv antibody expression of an antibody against the human protooncogen c-myc.

    PubMed

    Fuchs, P; Breitling, F; Little, M; Dübel, S

    1997-06-01

    The immunoglobulin heavy- and light-chain variable region (Vh and Vl) genes were isolated from Myc1-9E10 hybridoma cells, which secreted monoclonal antibody against human oncogen c-myc. The expression vector pOPE52-c-myc was constructed for the recombinant production in E. coli. A 30 kDa single chain fragment (scFv) expression product was found in the periplasmic space by SDS-PAGE and immunoblotting. A significant fraction was processed correctly as demonstrated with an antiserum recognizing the processed aminoterminus only. The specific binding of the scFv fragment to the peptide epitope of the maternal monoclonal antibody was demonstrated and the primary sequence of the variable regions was determined. Sequence comparison with previously published partial Vh and Vl sequences from this hybridoma cell line revealed a genetic heterogeneity for the light chain variable region. The potential use of this scFv as a new tool for detection and purification of tagged proteins, for adding costimulatory signals to the surface of cancer cells as well as for analyzing c-myc function in the living cell by cytoplasmic expression is discussed. PMID:9219032

  15. Regulation of c-Myc Expression by Ahnak Promotes Induced Pluripotent Stem Cell Generation.

    PubMed

    Lim, Hee Jung; Kim, Jusong; Park, Chang-Hwan; Lee, Sang A; Lee, Man Ryul; Kim, Kye-Seong; Kim, Jaesang; Bae, Yun Soo

    2016-01-01

    We have previously reported that Ahnak-mediated TGFβ signaling leads to down-regulation of c-Myc expression. Here, we show that inhibition of Ahnak can promote generation of induced pluripotent stem cells (iPSC) via up-regulation of endogenous c-Myc. Consistent with the c-Myc inhibitory role of Ahnak, mouse embryonic fibroblasts from Ahnak-deficient mouse (Ahnak(-/-) MEF) show an increased level of c-Myc expression compared with wild type MEF. Generation of iPSC with just three of the four Yamanaka factors, Oct4, Sox2, and Klf4 (hereafter 3F), was significantly enhanced in Ahnak(-/-) MEF. Similar results were obtained when Ahnak-specific shRNA was applied to wild type MEF. Of note, expressionof Ahnak was significantly induced during the formation of embryoid bodies from embryonic stem cells, suggesting that Ahnak-mediated c-Myc inhibition is involved in embryoid body formation and the initial differentiation of pluripotent stem cells. The iPSC from 3F-infected Ahnak(-/-) MEF cells (Ahnak(-/-)-iPSC-3F) showed expression of all stem cell markers examined and the capability to form three primary germ layers. Moreover, injection of Ahnak(-/-)-iPSC-3F into athymic nude mice led to development of teratoma containing tissues from all three primary germ layers, indicating that iPSC from Ahnak(-/-) MEF are bona fide pluripotent stem cells. Taken together, these data provide evidence for a new role for Ahnak in cell fate determination during development and suggest that manipulation of Ahnak and the associated signaling pathway may provide a means to regulate iPSC generation. PMID:26598518

  16. Structure-based Inhibitor Design for the Intrinsically Disordered Protein c-Myc

    PubMed Central

    Yu, Chen; Niu, Xiaogang; Jin, Fan; Liu, Zhirong; Jin, Changwen; Lai, Luhua

    2016-01-01

    Intrinsically disordered proteins (IDPs) are associated with various diseases and have been proposed as promising drug targets. However, conventional structure-based approaches cannot be applied directly to IDPs, due to their lack of ordered structures. Here, we describe a novel computational approach to virtually screen for compounds that can simultaneously bind to different IDP conformations. The test system used c-Myc, an oncoprotein containing a disordered basic helix-loop-helix-leucine zipper (bHLH-LZ) domain that adopts a helical conformation upon binding to Myc-associated factor X (Max). For the virtual screen, we used three binding pockets in representative conformations of c-Myc370–409, which is part of the disordered bHLH-LZ domain. Seven compounds were found to directly bind c-Myc370–409 in vitro, and four inhibited the growth of the c-Myc-overexpressing cells by affecting cell cycle progression. Our approach of IDP conformation sampling, binding site identification, and virtual screening for compounds that can bind to multiple conformations provides a useful strategy for structure-based drug discovery targeting IDPs. PMID:26931396

  17. Structure-based Inhibitor Design for the Intrinsically Disordered Protein c-Myc.

    PubMed

    Yu, Chen; Niu, Xiaogang; Jin, Fan; Liu, Zhirong; Jin, Changwen; Lai, Luhua

    2016-01-01

    Intrinsically disordered proteins (IDPs) are associated with various diseases and have been proposed as promising drug targets. However, conventional structure-based approaches cannot be applied directly to IDPs, due to their lack of ordered structures. Here, we describe a novel computational approach to virtually screen for compounds that can simultaneously bind to different IDP conformations. The test system used c-Myc, an oncoprotein containing a disordered basic helix-loop-helix-leucine zipper (bHLH-LZ) domain that adopts a helical conformation upon binding to Myc-associated factor X (Max). For the virtual screen, we used three binding pockets in representative conformations of c-Myc370-409, which is part of the disordered bHLH-LZ domain. Seven compounds were found to directly bind c-Myc370-409 in vitro, and four inhibited the growth of the c-Myc-overexpressing cells by affecting cell cycle progression. Our approach of IDP conformation sampling, binding site identification, and virtual screening for compounds that can bind to multiple conformations provides a useful strategy for structure-based drug discovery targeting IDPs. PMID:26931396

  18. c-Myc over-expression in Ramos Burkitt's lymphoma cell line predisposes to iron homeostasis disruption in vitro

    SciTech Connect

    Habel, Marie-Eve; Jung, Daniel . E-mail: djung@hema-quebec.qc.ca

    2006-03-24

    Burkitt's lymphoma is an aggressive B-cell neoplasm resulting from deregulated c-myc expression. We have previously shown that proliferation of Burkitt's lymphoma cell lines such as Ramos is markedly reduced by iron treatment. It has been shown that iron induces expression of c-myc which, owing to its transcriptional regulatory functions, regulates genes involved in iron metabolism. Transient enhancement of c-myc expression by iron could increase the expression of genes involved in iron incorporation, which could lead to an accumulation of intracellular free iron. Here, we have investigated whether cells with a high basal level of c-Myc were more likely to accumulate free iron. Our results suggest that the basal level of c-Myc in Ramos cells is twofold higher than what is seen in HL-60 cells. Moreover, in Ramos cells, where c-Myc is expressed at a high level, H-ferritin expression is down-regulated, transferrin receptor (CD71) expression is increased, and ferritin translation is inhibited. These modifications in iron metabolism, resulting from the strong basal expression of c-Myc, and amplified by iron addition, could lead to a disruption in homeostasis and consequently to growth arrest.

  19. Analysis of the tumorigenic potential of common marmoset lymphoblastoid cells expressing a constitutively activated c-myc gene.

    PubMed Central

    Hotchin, N. A.; Wedderburn, N.; Roberts, I.; Thomas, J. A.; Bungey, J. A.; Naylor, B.; Crawford, D. H.

    1993-01-01

    The respective roles of Epstein-Barr virus (EBV) and c-myc in the pathogenesis of endemic Burkitt's lymphoma (BL) are unclear. In order to help resolve the question whether constitutive expression of the c-myc gene in an EBV-immortalised B cell is sufficient to induce a tumorigenic phenotype, B cells from a common marmoset (Callithrix jacchus) were immortalised with EBV, transfected with a constitutively activated c-myc gene and inoculated into the host animals. Despite the cell line transfected with c-myc displaying enhanced growth characteristics, in vitro and in vivo experiments demonstrated that this was not sufficient to induce a tumorigenic phenotype. This supports our previous findings with EBV-immortalised human B cells transfected with an activated c-myc gene (Hotchin et al., 1990). Images Figure 1 Figure 2 Figure 4 PMID:8388232

  20. Activated α2-Macroglobulin Regulates Transcriptional Activation of c-MYC Target Genes through Cell Surface GRP78 Protein.

    PubMed

    Gopal, Udhayakumar; Gonzalez-Gronow, Mario; Pizzo, Salvatore Vincent

    2016-05-13

    Activated α2-macroglobulin (α2M*) signals predominantly through cell surface GRP78 (CS-GRP78) to promote proliferation and survival of cancer cells; however, the molecular mechanism remains obscure. c-MYC is an essential transcriptional regulator that controls cell proliferation. We hypothesize that α2M*/CS-GRP78-evoked key signaling events are required for transcriptional activation of c-MYC target genes. Activation of CS-GRP78 by α2M* requires ligation of the GRP78 primary amino acid sequence (Leu(98)-Leu(115)). After stimulation with α2M*, CS-GRP78 signaling activates 3-phosphoinositide-dependent protein kinase-1 (PDK1) to induce phosphorylation of PLK1, which in turn induces c-MYC transcription. We demonstrate that PLK1 binds directly to c-MYC and promotes its transcriptional activity by phosphorylating Ser(62) Moreover, activated c-MYC is recruited to the E-boxes of target genes FOSL1 and ID2 by phosphorylating histone H3 at Ser(10) In addition, targeting the carboxyl-terminal domain of CS-GRP78 with a mAb suppresses transcriptional activation of c-MYC target genes and impairs cell proliferation. This work demonstrates that α2M*/CS-GRP78 acts as an upstream regulator of the PDK1/PLK1 signaling axis to modulate c-MYC transcription and its target genes, suggesting a therapeutic strategy for targeting c-MYC-associated malignant progression. PMID:27002159

  1. Kindlin-3 interacts with the ribosome and regulates c-Myc expression required for proliferation of chronic myeloid leukemia cells

    PubMed Central

    Qu, Jing; Ero, Rya; Feng, Chen; Ong, Li-Teng; Tan, Hui-Foon; Lee, Hui-Shan; Ismail, Muhammad HB; Bu, Wen-Ting; Nama, Srikanth; Sampath, Prabha; Gao, Yong-Gui; Tan, Suet-Mien

    2015-01-01

    Kindlins are FERM-containing cytoplasmic proteins that regulate integrin-mediated cell-cell and cell-extracellular matrix (ECM) attachments. Kindlin-3 is expressed in hematopoietic cells, platelets, and endothelial cells. Studies have shown that kindlin-3 stabilizes cell adhesion mediated by ß1, ß2, and ß3 integrins. Apart from integrin cytoplasmic tails, kindlins are known to interact with other cytoplasmic proteins. Here we demonstrate that kindlin-3 can associate with ribosome via the receptor for activated-C kinase 1 (RACK1) scaffold protein based on immunoprecipitation, ribosome binding, and proximity ligation assays. We show that kindlin-3 regulates c-Myc protein expression in the human chronic myeloid leukemia cell line K562. Cell proliferation was reduced following siRNA reduction of kindlin-3 expression and a significant reduction in tumor mass was observed in xenograft experiments. Mechanistically, kindlin-3 is involved in integrin α5ß1-Akt-mTOR-p70S6K signaling; however, its regulation of c-Myc protein expression could be independent of this signaling axis. PMID:26677948

  2. Genomic targets of the human c-Myc protein

    PubMed Central

    Fernandez, Paula C.; Frank, Scott R.; Wang, Luquan; Schroeder, Marianne; Liu, Suxing; Greene, Jonathan; Cocito, Andrea; Amati, Bruno

    2003-01-01

    The transcription factor Myc is induced by mitogenic signals and regulates downstream cellular responses. If overexpressed, Myc promotes malignant transformation. Myc modulates expression of diverse genes in experimental systems, but few are proven direct targets. Here, we present a large-scale screen for genomic Myc-binding sites in live human cells. We used bioinformatics to select consensus DNA elements (CACGTG or E-boxes) situated in the 5′ regulatory region of genes and measured Myc binding to those sequences in vivo by quantitative chromatin immunoprecipitation. Strikingly, most promoter-associated E-boxes showed selective recovery with Myc, unlike non-E-box promoters or E-boxes in bulk genomic DNA. Promoter E-boxes were distributed in two groups bound by Myc at distinct frequencies. The high-affinity group included an estimated 11% of all cellular loci, was highly conserved among different cells, and was bound independently of Myc expression levels. Overexpressed Myc associated at increased frequency with low-affinity targets and, at extreme levels, also with other sequences, suggesting that some binding was not sequence-specific. The strongest DNA-sequence parameter defining high-affinity targets was the location of E-boxes within CpG islands, correlating with an open, preacetylated state of chromatin. Myc further enhanced histone acetylation, with or without accompanying induction of mRNA expression. Our findings point to a high regulatory and biological diversity among Myc-target genes. PMID:12695333

  3. c-MYC expression sensitizes medulloblastoma cells to radio- and chemotherapy and has no impact on response in medulloblastoma patients

    PubMed Central

    2011-01-01

    Background To study whether and how c-MYC expression determines response to radio- and chemotherapy in childhood medulloblastoma (MB). Methods We used DAOY and UW228 human MB cells engineered to stably express different levels of c-MYC, and tested whether c-MYC expression has an effect on radio- and chemosensitivity using the colorimetric 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium inner salt (MTS) assay, clonogenic survival, apoptosis assays, cell cycle analysis, and western blot assessment. In an effort to validate our results, we analyzed c-MYC mRNA expression in formalin-fixed paraffin-embedded tumor samples from well-documented patients with postoperative residual tumor and compared c-MYC mRNA expression with response to radio- and chemotherapy as examined by neuroradiological imaging. Results In DAOY - and to a lesser extent in UW228 - cells expressing high levels of c-MYC, the cytotoxicity of cisplatin, and etoposide was significantly higher when compared with DAOY/UW228 cells expressing low levels of c-MYC. Irradiation- and chemotherapy-induced apoptotic cell death was enhanced in DAOY cells expressing high levels of c-MYC. The response of 62 of 66 residual tumors was evaluable and response to postoperative radio- (14 responders (CR, PR) vs. 5 non-responders (SD, PD)) or chemotherapy (23 CR/PR vs. 20 SD/PD) was assessed. c-MYC mRNA expression was similar in primary MB samples of responders and non-responders (Mann-Whitney U test, p = 0.50, ratio 0.49, 95% CI 0.008-30.0 and p = 0.67, ratio 1.8, 95% CI 0.14-23.5, respectively). Conclusions c-MYC sensitizes MB cells to some anti-cancer treatments in vitro. As we failed to show evidence for such an effect on postoperative residual tumors when analyzed by imaging, additional investigations in xenografts and larger MB cohorts may help to define the exact function of c-MYC in modulating response to treatment. PMID:21324178

  4. c-myc activation renders proliferation of Epstein-Barr virus (EBV)-transformed cells independent of EBV nuclear antigen 2 and latent membrane protein 1.

    PubMed Central

    Polack, A; Hörtnagel, K; Pajic, A; Christoph, B; Baier, B; Falk, M; Mautner, J; Geltinger, C; Bornkamm, G W; Kempkes, B

    1996-01-01

    Two genetic events contribute to the development of endemic Burkitt lymphoma (BL) infection of B lymphocytes with Epstein-Barr virus (EBV) and the activation of the protooncogene c-myc through chromosomal translocation. The viral genes EBV nuclear antigen 2 (EBNA2) and latent membrane protein 1 (LMP1) are essential for transformation of primary human B cells by EBV in vitro; however, these genes are not expressed in BL cells in vivo. To address the question whether c-myc activation might abrogate the requirement of the EBNA2 and LMP1 function, we have introduced an activated c-myc gene into an EBV-transformed cell line in which EBNA2 was rendered estrogen-dependent through fusion with the hormone binding domain of the estrogen receptor. The c-myc gene was placed under the control of regulatory elements of the immunoglobulin kappa locus composed a matrix attachment region, the intron enhancer, and the 3' enhancer. We show here that transfection of a c-myc expression plasmid followed by selection for high MYC expression is capable of inducing continuous proliferation of these cells in the absence of functional EBNA2 and LMP1. c-myc-induced hormone-independent proliferation was associated with a dramatic change in the growth behavior as well as cell surface marker expression of these cells. The typical lymphoblastoid morphology and phenotype of EBV-transformed cells completely changed into that of BL cells in vivo. We conclude that the phenotype of BL cells reflects the expression pattern of viral and cellular genes rather than its germinal center origin. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 Fig. 6 PMID:8816814

  5. Availability of subfertile transgenic rats expressing the c-myc gene as recipients for spermatogonial transplantation.

    PubMed

    Hirabayashi, Masumi; Yoshizawa, Yusuke; Kato, Megumi; Tsuchiya, Takashi; Nagao, Shizuko; Hochi, Shinichi

    2009-02-01

    The spermatogonial transplantation system was applied to evaluate stem cell kinetics and niche quality and to produce gene-modified animals using the stem cells after homologous recombination-based selection. This study was designed to determine whether the transplanted spermatogonia were able to proliferate and differentiate in male rats expressing the c-myc transgene under control of the human metallothionein IIA promoter (MT-myc Tg rats). Donor testicular cells were prepared from heterozygous chicken beta actin (CAG)/enhanced green fluorescent protein (EGFP)-transgenic rats (EGFP Tg rats) during the second week after birth and injected into the seminiferous tubules of the MT-myc Tg rats (line-A and -B; both subfertile) or rats pretreated with busulfan to remove endogenous spermatogonia. Three to four months after transplantation, cell colonies with EGFP fluorescence were detected in 36% (4/11), 40% (8/20), and 71% (5/7) of the transplanted testes in line-A MT-myc Tg rats, line-B MT-myc Tg rats, and busulfan-treated rats, respectively. No EGFP-positive colonies were detected when wild-type male rats were used as recipients (0/7; testis-basis). The histopathological and immunofluorescent examination of the serial sections from the transplanted testes showed normal spermatogenesis of the donor spermatogonia, but atrophy of the recipient seminiferous tubules. Microinsemination with round spermatids and mature spermatozoa derived from EGFP-positive testes in line-A rats resulted 26% (10/39 transferred) and 23% (11/48 transferred) full-term offspring, respectively. Thus, the MT-myc Tg male rats were suitable as potent recipients for spermatogonial transplantation without any chemical pretreatment to remove the endogenous spermatogonia. PMID:18830680

  6. Bombesin stimulation of c-fos and c-myc gene expression in cultured of Swiss 3T3 cells

    SciTech Connect

    Palumbo, A.P.; Rossino, P.; Comoglio, P.M.

    1986-11-01

    Bombesin has been show to be a potent mitogen for Swiss 3T3 cells. At nanomolar concentrations it stimulates DNA synthesis in quiescent cultures of 3T3 cells and also induces the expression of c-fos and c-myc mRNA. c-fos mRNA transcripts dramatically increase 15 min after the addition of bombesin, are still abundant after 30-60 min and then decrease. c-myc mRNA induction is detectable later, 1 h after bombesin treatment. Conversely, no changes in c-Ki-ras expression are observed after stimulation with bombesin. These results demonstrate that the increased expression of c-fos and c-myc mRNAs appears to be a common response to diverse agents that induce DNA synthesis and cell proliferation.

  7. Immunochemical detection of proteins related to the human c-myc exon 1.

    PubMed Central

    Gazin, C; Rigolet, M; Briand, J P; Van Regenmortel, M H; Galibert, F

    1986-01-01

    Published sequence data of the human c-myc gene indicate the presence of a coding capacity for a polypeptide of 188 residues within the first exon. Using antibodies raised against five synthetic peptides corresponding to different non-over-lapping parts of this polypeptide, two proteins of 32 kd and 58 kd antigenically related to the synthetic peptides have been detected in extracts of human cells. The confidence of this detection has been reinforced by showing that epitopes corresponding to different peptides were indeed located on the same molecule and that the 58 kd protein appears to be a dimeric form of the 32 kd protein. That these proteins originate from the first exon was indicated by: hybrid-arrested translation experiments followed by immunodetection of the translation products; in vitro translation of messenger RNA derived from cloned exon 1 by SP6 polymerase transcription. Images Fig. 1. Fig. 2. Fig. 3. Fig. 4. Fig. 5. Fig. 6. Fig. 7. PMID:2430795

  8. Gene Therapy of c-myc Suppressor FUSE-Binding Protein-Interacting Repressor by Sendai Virus Delivery Prevents Tracheal Stenosis

    PubMed Central

    Mizokami, Daisuke; Araki, Koji; Tanaka, Nobuaki; Suzuki, Hiroshi; Tomifuji, Masayuki; Yamashita, Taku; Ueda, Yasuji; Shimada, Hideaki; Matsushita, Kazuyuki; Shiotani, Akihiro

    2015-01-01

    Acquired tracheal stenosis remains a challenging problem for otolaryngologists. The objective of this study was to determine whether the Sendai virus (SeV)-mediated c-myc suppressor, a far upstream element (FUSE)-binding protein (FBP)-interacting repressor (FIR), modulates wound healing of the airway mucosa, and whether it prevents tracheal stenosis in an animal model of induced mucosal injury. A fusion gene-deleted, non-transmissible SeV vector encoding FIR (FIR-SeV/ΔF) was prepared. Rats with scraped airway mucosae were administered FIR-SeV/ΔF through the tracheostoma. The pathological changes in the airway mucosa and in the tracheal lumen were assessed five days after scraping. Untreated animals showed hyperplasia of the airway epithelium and a thickened submucosal layer with extensive fibrosis, angiogenesis, and collagen deposition causing lumen stenosis. By contrast, the administration of FIR-SeV/ΔF decreased the degree of tracheal stenosis (P < 0.05) and improved the survival rate (P < 0.05). Immunohistochemical staining showed that c-Myc expression was downregulated in the tracheal basal cells of the FIR-SeV/ΔF-treated animals, suggesting that c-myc was suppressed by FIR-SeV/ΔF in the regenerating airway epithelium of the injured tracheal mucosa. The airway-targeted gene therapy of the c-myc suppressor FIR, using a recombinant SeV vector, prevented tracheal stenosis in a rat model of airway mucosal injury. PMID:25569246

  9. Baicalein suppresses the viability of MG-63 osteosarcoma cells through inhibiting c-MYC expression via Wnt signaling pathway.

    PubMed

    He, Nengbin; Zhang, Zhichang

    2015-07-01

    The major reason responsible for the poor prognosis of osteosarcoma is the malignant proliferation of osteosarcoma cells. The activated Wnt/β-catenin signaling induces c-MYC gene transcription and results in osteocytes' carcinomatous change, which contributes to osteosarcoma development, so c-MYC gene is one of the therapeutic targets. The role of multiple botanical extracts in the expression of β-catenin's target gene c-MYC in osteosarcoma MG-63 cells was tested by cellomics high content screening. Baicalein was identified as the most effective one which can inhibit the proliferation and promote the apoptosis of MG-63 cells in a dose-dependent manner by cell counting kit-8 test and fluorescence-activated cell sorting, respectively. This process was associated with the decreased levels of β-catenin and its target gene c-MYC, identified by q-PCR and Western blotting, respectively. When MG-63 cells were treated with both baicalein and JNK inhibitor SP600125, the apoptosis and expression of c-MYC were not significantly decreased. After the construct pcDNA3.1-BANCR (BRAF-regulated lncRNA 1) was transfected into MG-63 cells, RT-PCR, Western blotting and CCK-8 assay showed that BANCR was positively correlated with baicalein. These results indicated that baicalein inhibited osteosarcoma cell proliferation and promoted apoptosis by targeting c-MYC gene through Wnt signaling, in which JNK and BANCR were also involved as well as β-catenin, suggesting a new potential mechanism for us to better understand the inhibiting effect of baicalein on osteosarcoma. PMID:25893737

  10. Cytotoxicity and altered c-myc gene expression by medical polyacrylamide hydrogel.

    PubMed

    Xi, T F; Fan, C X; Feng, X M; Wan, Z Y; Wang, C R; Chou, L L

    2006-08-01

    Medical Polyacrylamide Hydrogel (PAMG)has been used in plastic and aesthetic surgery for years. However, its safety is still in doubt in many countries. In the current research, first an approach, using high performance liquid chromatography (HPLC), to determine the amount of residual acrylamide monomer (AM) in the PAMG was presented. Then the cytotoxicity of PAMG was investigated using cell counting and methyl thiazolyl tetrazolium (MTT) assay. To explore the mechanism of this toxicity, normal human fibroblasts cultured in medium extracts were analyzed. Membrane changes and other related parameters were investigated using flow cytometry (FCM). Real time fluorescent polymerase chain reaction (real time PCR) was also introduced to determine the biological response of the fibroblasts. During this process, three representative genes (p53, beta-actin, and c-myc, which are tumor suppressor genes, housekeeping genes, and proto-oncogenes respectively) were selected for examination. Results indicated that a method based on HPLC is practical and simple for determining AM in PAMG. The detection limits can reach the desired ppb level, and so it can fully meet the requirements of the studies of PAMG. Polyacylamide Hydrogel inhibits the growth of human fibroblasts and may cause the apoptosis of human fibroblasts. Moreover, it can alter physical parameters such as the size and the granularity of these cells. Furthermore, these three genes have a relatively typical amplification plot and highly related, wide-range standard curves, and so this reaction system is definitely suitable for the semiquantification of these genes. PAMG induces the increase of the message ribonucleic acid (mRNA) expression of c-myc, while the p53 and beta-actin remain even. This change is not related to the concentration of AM in the gel and may be incited by other components in the extract of PMAG. PMID:16637045

  11. Physiological Expression and Accumulation of the Products of Two Upstream Open Reading Frames mrtl and MycHex1 Along With p64 and p67 Myc From the Human c-myc Locus.

    PubMed

    Ji, Mi Hong; Kim, Seung-Ki; Kim, Chae-Yong; Phi, Ji Hoon; Jun, Hyun Jin; Blume, Scott W; Choi, Hyoung Soo

    2016-06-01

    In addition to the canonical c-Myc p64 and p67 proteins, the human c-myc locus encodes two distinct proteins, mrtl (myc-related translation/localization regulatory factor) and MycHex1 (Myc Human Exon 1), from the upstream open reading frames within the 5'-untranslated region of the c-myc P0 mRNA. The aim of this study is to examine simultaneously, for the first time, mrtl, MycHex1, c-Myc p64, and p67 in human tumor cell lines and pediatric brain tumor tissues. Western blot analysis demonstrated endogenous mrtl, MycHex1, c-Myc p64, and p67 simultaneously. The relative abundance of mrtl and MycHex1 were consistent among a variety of human tumor cell lines, and the relative intensities of mrtl and MycHex1 correlated positively. Confocal imaging revealed mrtl predominantly localized to the nuclear envelope, along with prominent reticular pattern in the cytoplasm. MycHex1 was observed as a series of bright foci located within the nucleus, a subset of which colocalized with fibrillarin. mrtl and MycHex1 co-immunoprecipitated with RACK1, c-Myc, fibrillarin, coilin, and with each other. These findings suggest that mrtl and MycHex1 have multiple interaction partners in both the nucleus and cytoplasm. Sequence analyses confirmed a known polymorphism of mrtl at base 1965 (G>T) and new mutations at bases 1900 (C>G) and 1798 (C>G). Evidence is presented for expression and stable accumulation of all four proteins encoded by three distinct non-overlapping open reading frames within the human c-myc locus. Additional work is warranted to further elucidate the functional or regulatory roles of these molecules in regulation of c-Myc and in oncogenesis. J. Cell. Biochem. 117: 1407-1418, 2016. © 2015 Wiley Periodicals, Inc. PMID:26552949

  12. c-Myc regulates proliferation and Fgf10 expression in airway smooth muscle after airway epithelial injury in mouse.

    PubMed

    Volckaert, Thomas; Campbell, Alice; De Langhe, Stijn

    2013-01-01

    During lung development, Fibroblast growth factor 10 (Fgf10), which is expressed in the distal mesenchyme and regulated by Wnt signaling, acts on the distal epithelial progenitors to maintain them and prevent them from differentiating into proximal (airway) epithelial cells. Fgf10-expressing cells in the distal mesenchyme are progenitors for parabronchial smooth muscle cells (PSMCs). After naphthalene, ozone or bleomycin-induced airway epithelial injury, surviving epithelial cells secrete Wnt7b which then activates the PSMC niche to induce Fgf10 expression. This Fgf10 secreted by the niche then acts on a subset of Clara stem cells to break quiescence, induce proliferation and initiate epithelial repair. Here we show that conditional deletion of the Wnt target gene c-Myc from the lung mesenchyme during development does not affect proper epithelial or mesenchymal differentiation. However, in the adult lung we show that after naphthalene-mediated airway epithelial injury c-Myc is important for the activation of the PSMC niche and as such induces proliferation and Fgf10 expression in PSMCs. Our data indicate that conditional deletion of c-Myc from PSMCs inhibits airway epithelial repair, whereas c-Myc ablation from Clara cells has no effect on airway epithelial regeneration. These findings may have important implications for understanding the misregulation of lung repair in asthma and COPD. PMID:23967208

  13. Survivin enhances telomerase activity via up-regulation of specificity protein 1- and c-Myc-mediated human telomerase reverse transcriptase gene transcription

    SciTech Connect

    Endoh, Teruo; Tsuji, Naoki; Asanuma, Koichi; Yagihashi, Atsuhito; Watanabe, Naoki . E-mail: watanabn@sapmed.ac.jp

    2005-05-01

    Suppression of apoptosis is thought to contribute to carcinogenesis. Survivin, a member of the inhibitor-of-apoptosis family, blocks apoptotic signaling activated by various cellular stresses. Since elevated expression of survivin observed in human cancers of varied origin was associated with poor patient survival, survivin has attracted growing attention as a potential target for cancer treatment. Immortalization of cells also is required for carcinogenesis; telomere length maintenance by telomerase is required for cancer cells to proliferate indefinitely. Yet how cancer cells activate telomerase remains unclear. We therefore examined possible interrelationships between survivin expression and telomerase activity. Correlation between survivin and human telomerase reverse transcriptase (hTERT) expression was observed in colon cancer tissues, and overexpression of survivin enhanced telomerase activity by up-regulation of hTERT expression in LS180 human colon cancer cells. DNA-binding activities of specificity protein 1 (Sp1) and c-Myc to the hTERT core promoter were increased in survivin gene transfectant cells. Phosphorylation of Sp1 and c-Myc at serine and threonine residues was enhanced by survivin, while total amounts of these proteins were unchanged. Further, 'knockdown' of survivin by a small inhibitory RNA decreased Sp1 and c-Myc phosphorylation. Thus survivin participates not only in inhibition of apoptosis, but also in prolonging cellular lifespan.

  14. Endoglin inhibits ERK-induced c-Myc and cyclin D1 expression to impede endothelial cell proliferation

    SciTech Connect

    Pan, Christopher C.; Bloodworth, Jeffrey C.; Mythreye, Karthikeyan; Lee, Nam Y.

    2012-08-03

    Highlights: Black-Right-Pointing-Pointer Endoglin inhibits ERK activation in endothelial cells. Black-Right-Pointing-Pointer Endoglin is a regulator of c-Myc and cyclin D1 expression. Black-Right-Pointing-Pointer {beta}-arrestin2 interaction with endoglin is required for ERK/c-Myc repression. Black-Right-Pointing-Pointer Endoglin impedes cellular proliferation by targeting ERK-induced mitogenic signaling. -- Abstract: Endoglin is an endothelial-specific transforming growth factor beta (TGF-{beta}) co-receptor essential for angiogenesis and vascular remodeling. Endoglin regulates a wide range of cellular processes, including cell adhesion, migration, and proliferation, through TGF-{beta} signaling to canonical Smad and Smad-independent pathways. Despite its overall pro-angiogenic role in the vasculature, the underlying mechanism of endoglin action is poorly characterized. We previously identified {beta}-arrestin2 as a binding partner that causes endoglin internalization from the plasma membrane and inhibits ERK signaling towards endothelial migration. In the present study, we examined the mechanistic role of endoglin and {beta}-arrestin2 in endothelial cell proliferation. We show that endoglin impedes cell growth through sustained inhibition of ERK-induced c-Myc and cyclin D1 expression in a TGF-{beta}-independent manner. The down-regulation of c-Myc and cyclin D1, along with growth-inhibition, are reversed when the endoglin/{beta}-arrestin2 interaction is disrupted. Given that TGF-{beta}-induced Smad signaling potently represses c-Myc in most cell types, our findings here show a novel mechanism by which endoglin augments growth-inhibition by targeting ERK and key downstream mitogenic substrates.

  15. NODAL DIFFUSE LARGE B-CELL LYMPHOMAS IN CHILDREN AND ADOLESCENTS: IMMUNOHISTOCHEMICAL EXPRESSION PATTERNS AND C-MYC TRANSLOCATION IN RELATION TO CLINICAL OUTCOME

    PubMed Central

    Gualco, Gabriela; Weiss, Lawrence M.; Harrington, William J.; Bacchi, Carlos E.

    2009-01-01

    Diffuse large B-cell lymphoma (DLBCL) is a very infrequent neoplasm in the pediatric age group; therefore there are very few studies on the immunophenotype or genetics of these cases. We studied a series of 16 patients with nodal DLBCL occurring in patients between 10 and 18 years of age. The cases were classified according to the 2008 World Health Organization classification criteria, with application of immunohistochemistry for the detection of CD10, BCL-6 and MUM1 proteins to divide the lymphomas into germinal center and non-germinal center types. In addition, TCL1, BCL-2 expression, and the Ki-67 proliferation index were evaluated by immunohistochemistry, and c-MYC and BCL-2 translocations were evaluated by FISH. All these parameters were correlated with clinical features and outcome. Our study revealed that centroblastic morphology and the germinal center type of DLBCL are more prevalent in these young patients (63%), with 37% containing a c-MYC translocation. Only one case showed a BCL-2 translocation, reflecting a double-hit case with features intermediate between DLBCL and Burkitt lymphoma. We found a higher frequency of BCL-2 expression than previously reported, with no direct influence on the outcome of the disease in univariate or multivariate analysis. The expression of TCL1 has not been specifically studied in nodal pediatric DLBCL before; we found a 31% incidence of TCL1 expression. MUM1 expression was observed in 44% of the cases and these positive cases showed a significant negative impact on clinical outcome. TCL1 is directly and significantly associated with the presence of c-MYC and a high proliferative index. The germinal center and non-germinal center subtypes showed significant differences for both overall survival and disease-free interval. C-MYC translocation was found in 37% of patients, and had a favorable impact on clinical outcome. We conclude that nodal pediatric and adolescent DLBCL are mainly of the germinal center type, with a

  16. Sodium arsenite alters cell cycle and MTHFR, MT1/2, and c-Myc protein levels in MCF-7 cells

    SciTech Connect

    Ruiz-Ramos, Ruben; Lopez-Carrillo, Lizbeth; Albores, Arnulfo; Hernandez-Ramirez, Raul U.; Cebrian, Mariano E.

    2009-12-15

    There is limited available information on the effects of arsenic on enzymes participating in the folate cycle. Therefore, our aim was to evaluate the effects of sodium arsenite on the protein levels of methylenetetrahydrofolate reductase (MTHFR) and dihydrofolate reductase (DHFR) and its further relationship with the expression MT1/2 and c-myc in MCF-7 cells. Arsenite treatment (0-10 muM) for 4 h decreased MTHFR levels in a concentration-dependent fashion without significant effects on DHFR. The effects on MTHFR were observed at arsenite concentrations not significantly affecting cell viability. We also observed an increase in S-phase recruitment at all concentrations probed. Lower concentrations (< 5 muM) induced cell proliferation, showing a high proportion of BrdU-stained cells, indicating a higher DNA synthesis rate. However, higher concentrations (>= 5 muM) or longer treatment periods induced apoptosis. Arsenite also induced dose-dependent increases in MT1/2 and c-Myc protein levels. The levels of MTHFR were inversely correlated to MT1/2 and c-Myc overexpression and increased S-phase recruitment. Our findings indicate that breast epithelial cells are responsive to arsenite and suggest that exposure may pose a risk for breast cancer. The reductions in MTHFR protein levels contribute to understand the mechanisms underlying the induction of genes influencing growth regulation, such as c-myc and MT1/2. However, further research is needed to ascertain if the effects here reported following short-time and high-dose exposure are relevant for human populations chronically exposed to low arsenic concentrations.

  17. Equol, an isoflavone metabolite, regulates cancer cell viability and protein synthesis initiation via c-Myc and eIF4G.

    PubMed

    de la Parra, Columba; Borrero-Garcia, Luis D; Cruz-Collazo, Ailed; Schneider, Robert J; Dharmawardhane, Suranganie

    2015-03-01

    Epidemiological studies implicate dietary soy isoflavones as breast cancer preventives, especially due to their anti-estrogenic properties. However, soy isoflavones may also have a role in promoting breast cancer, which has yet to be clarified. We previously reported that equol, a metabolite of the soy isoflavone daidzein, may advance breast cancer potential via up-regulation of the eukaryotic initiation factor 4GI (eIF4GI). In estrogen receptor negative (ER-) metastatic breast cancer cells, equol induced elevated levels of eIF4G, which were associated with increased cell viability and the selective translation of mRNAs that use non-canonical means of initiation, including internal ribosome entry site (IRES), ribosome shunting, and eIF4G enhancers. These mRNAs typically code for oncogenic, survival, and cell stress molecules. Among those mRNAs translationally increased by equol was the oncogene and eIF4G enhancer, c-Myc. Here we report that siRNA-mediated knockdown of c-Myc abrogates the increase in cancer cell viability and mammosphere formation by equol, and results in a significant down-regulation of eIF4GI (the major eIF4G isoform), as well as reduces levels of some, but not all, proteins encoded by mRNAs that are translationally stimulated by equol treatment. Knockdown of eIF4GI also markedly reduces an equol-mediated increase in IRES-dependent mRNA translation and the expression of specific oncogenic proteins. However, eIF4GI knockdown did not reciprocally affect c-Myc levels or cell viability. This study therefore implicates c-Myc as a potential regulator of the cancer-promoting effects of equol via up-regulation of eIF4GI and selective initiation of translation on mRNAs that utilize non-canonical initiation, including certain oncogenes. PMID:25593313

  18. Blocking c-myc and stat3 by E. coli expressed and enzyme digested siRNA in mouse melanoma

    SciTech Connect

    Hong Jie; Zhao Yingchun; Huang Weida . E-mail: whuang@fudan.edu.cn

    2006-09-22

    Tumour cells often show alteration in the signal-transduction pathways, leading to proliferation in response to external signals. Oncogene overexpression and constitutive expression is a common phenomenon in the development and progression of many human cancers. Therefore oncogenes provide potential targets for cancer therapy. RNA interference (RNAi), mediated by small interfering RNA (siRNA), silences genes with a high degree of specificity and potentially represents a general approach for molecularly targeted anti-cancer therapy. The data presented in this report evaluated the method of systemically administering combined esiRNAs to multiple targets as compared with the method of using a single kind of esiRNA to a single target. Our experimental data revealed that the mixed treatment of esiC-MYC and esiSTAT3 had a better inhibition effect than the single treatment of esiC-MYC or esiSTAT3 on mouse B16 melanoma.

  19. Targeting c-MYC in Platinum-Resistant Ovarian Cancer.

    PubMed

    Reyes-González, Jeyshka M; Armaiz-Peña, Guillermo N; Mangala, Lingegowda S; Valiyeva, Fatma; Ivan, Cristina; Pradeep, Sunila; Echevarría-Vargas, Ileabett M; Rivera-Reyes, Adrian; Sood, Anil K; Vivas-Mejía, Pablo E

    2015-10-01

    The purpose of this study was to investigate the molecular and therapeutic effects of siRNA-mediated c-MYC silencing in cisplatin-resistant ovarian cancer. Statistical analysis of patient's data extracted from The Cancer Genome Atlas (TCGA) portal showed that the disease-free (DFS) and the overall (OS) survival were decreased in ovarian cancer patients with high c-MYC mRNA levels. Furthermore, analysis of a panel of ovarian cancer cell lines showed that c-MYC protein levels were higher in cisplatin-resistant cells when compared with their cisplatin-sensitive counterparts. In vitro cell viability, growth, cell-cycle progression, and apoptosis, as well as in vivo therapeutic effectiveness in murine xenograft models, were also assessed following siRNA-mediated c-MYC silencing in cisplatin-resistant ovarian cancer cells. Significant inhibition of cell growth and viability, cell-cycle arrest, and activation of apoptosis were observed upon siRNA-mediated c-MYC depletion. In addition, single weekly doses of c-MYC-siRNA incorporated into 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-[methoxy(polyethylene glycol)-2000] (DSPE-PEG-2000)-based nanoliposomes resulted in significant reduction in tumor growth. These findings identify c-MYC as a potential therapeutic target for ovarian cancers expressing high levels of this oncoprotein. PMID:26227489

  20. MYCN/c-MYC-induced microRNAs repress coding gene networks associated with poor outcome in MYCN/c-MYC-activated tumors.

    PubMed

    Mestdagh, P; Fredlund, E; Pattyn, F; Schulte, J H; Muth, D; Vermeulen, J; Kumps, C; Schlierf, S; De Preter, K; Van Roy, N; Noguera, R; Laureys, G; Schramm, A; Eggert, A; Westermann, F; Speleman, F; Vandesompele, J

    2010-03-01

    Increased activity of MYC protein-family members is a common feature in many cancers. Using neuroblastoma as a tumor model, we established a microRNA (miRNA) signature for activated MYCN/c-MYC signaling in two independent primary neuroblastoma tumor cohorts and provide evidence that c-MYC and MYCN have overlapping functions. On the basis of an integrated approach including miRNA and messenger RNA (mRNA) gene expression data we show that miRNA activation contributes to widespread mRNA repression, both in c-MYC- and MYCN-activated tumors. c-MYC/MYCN-induced miRNA activation was shown to be dependent on c-MYC/MYCN promoter binding as evidenced by chromatin immunoprecipitation. Finally, we show that pathways, repressed through c-MYC/MYCN miRNA activation, are highly correlated to tumor aggressiveness and are conserved across different tumor entities suggesting that c-MYC/MYCN activate a core set of miRNAs for cooperative repression of common transcriptional programs related to disease aggressiveness. Our results uncover a widespread correlation between miRNA activation and c-MYC/MYCN-mediated coding gene expression modulation and further substantiate the overlapping functions of c-MYC and MYCN in the process of tumorigenesis. PMID:19946337

  1. Study of C-MYC amplification and expression in Iranian gastric cancer samples using CISH and IHC methods

    PubMed Central

    Khaleghian, Malihea; Jahanzad, Issa; Shakoori, Abbas; Ardalan, Farid Azmoudeh; Azimi, Cyrus

    2015-01-01

    Background: Gastric cancer is the fourth most frequent malignancy and the second cause of cancer-related mortality worldwide. It has been suggested that in gastric carcinogenesis, the C-MYC gene has an important function. The objective of this study is to establish the preference of Chromogenic in situ hybridization (CISH) and Immunohistochemistry (IHC) in the diagnosis and prognosis of gastric cancer. Materials and Methods: Samples comprised of 50 randomly selected patients of whom 40 were male and 10 female. To evaluate the MYC copy number and its protein expression, CISH and IHC analyses were performed for 50 gastric adenocarcinomas, in Iran. Results: The location of the tumor in 64% of the patients was the fundus, and in 72% of patients, the tumors were of a diffuse type; 22 samples showed no amplification, and 28 samples were with amplification. MYC immunoreactivity was observed in 13 samples. Twelve samples showed both MYC amplification and MYC immunoreactivity. In addition, among the 28 CISH+ samples, 12 samples had positive signals for IHC and 16 samples had negative signals for IHC. A majority of the IHC-negative patients had no amplification, but only one patient with IHC positive had no amplification. Conclusion: Our conclusion was that for the management and treatment of gastric cancer, and for special attention of clinicians, for prognosis and tumor progression, the CISH was a better and more feasible test than IHC, in regard to the sensitivity and specificity. PMID:26261818

  2. Measles Virus Infection Inactivates Cellular Protein Phosphatase 5 with Consequent Suppression of Sp1 and c-Myc Activities

    PubMed Central

    Sato, Hiroki; Yoneda, Misako; Honma, Reiko; Ikeda, Fusako; Watanabe, Shinya

    2015-01-01

    ABSTRACT Measles virus (MeV) causes several unique syndromes, including transient immunosuppression. To clarify the cellular responses to MeV infection, we previously analyzed a MeV-infected epithelial cell line and a lymphoid cell line by microarray and showed that the expression of numerous genes was up- or downregulated in the epithelial cells. In particular, there was a characteristic comprehensive downregulation of housekeeping genes during late stage infection. To identify the mechanism underlying this phenomenon, we examined the phosphorylation status of transcription factors and kinase/phosphatase activities in epithelial cells after infection. MeV infection inactivated cellular protein phosphatase 5 (PP5) that consequently inactivated DNA-dependent protein kinase, which reduced Sp1 phosphorylation levels, and c-Myc degradation, both of which downregulated the expression of many housekeeping genes. In addition, intracellular accumulation of viral nucleocapsid inactivated PP5 and subsequent downstream responses. These findings demonstrate a novel strategy of MeV during infection, which causes the collapse of host cellular functions. IMPORTANCE Measles virus (MeV) is one of the most important pathogens in humans. We previously showed that MeV infection induces the comprehensive downregulation of housekeeping genes in epithelial cells. By examining this phenomenon, we clarified the molecular mechanism underlying the constitutive expression of housekeeping genes in cells, which is maintained by cellular protein phosphatase 5 (PP5) and DNA-dependent protein kinase. We also demonstrated that MeV targets PP5 for downregulation in epithelial cells. This is the first report to show how MeV infection triggers a reduction in overall cellular functions of infected host cells. Our findings will help uncover unique pathogenicities caused by MeV. PMID:26157124

  3. Rictor regulates FBXW7-dependent c-Myc and cyclin E degradation in colorectal cancer cells

    SciTech Connect

    Guo, Zheng; Zhou, Yuning; Evers, B. Mark; Wang, Qingding

    2012-02-10

    Highlights: Black-Right-Pointing-Pointer Rictor associates with FBXW7 to form an E3 complex. Black-Right-Pointing-Pointer Knockdown of rictor decreases ubiquitination of c-Myc and cylin E. Black-Right-Pointing-Pointer Knockdown of rictor increases protein levels of c-Myc and cylin E. Black-Right-Pointing-Pointer Overexpression of rictor induces the degradation of c-Myc and cyclin E proteins. Black-Right-Pointing-Pointer Rictor regulation of c-Myc and cyclin E requires FBXW7. -- Abstract: Rictor (Rapamycin-insensitive companion of mTOR) forms a complex with mTOR and phosphorylates and activates Akt. Activation of Akt induces expression of c-Myc and cyclin E, which are overexpressed in colorectal cancer and play an important role in colorectal cancer cell proliferation. Here, we show that rictor associates with FBXW7 to form an E3 complex participating in the regulation of c-Myc and cyclin E degradation. The Rictor-FBXW7 complex is biochemically distinct from the previously reported mTORC2 and can be immunoprecipitated independently of mTORC2. Moreover, knocking down of rictor in serum-deprived colorectal cancer cells results in the decreased ubiquitination and increased protein levels of c-Myc and cyclin E while overexpression of rictor induces the degradation of c-Myc and cyclin E proteins. Genetic knockout of FBXW7 blunts the effects of rictor, suggesting that rictor regulation of c-Myc and cyclin E requires FBXW7. Our findings identify rictor as an important component of FBXW7 E3 ligase complex participating in the regulation of c-Myc and cyclin E protein ubiquitination and degradation. Importantly, our results suggest that elevated growth factor signaling may contribute to decrease rictor/FBXW7-mediated ubiquitination of c-Myc and cyclin E, thus leading to accumulation of cyclin E and c-Myc in colorectal cancer cells.

  4. Targeting of the MYCN Protein with Small Molecule c-MYC Inhibitors

    PubMed Central

    Müller, Inga; Larsson, Karin; Frenzel, Anna; Oliynyk, Ganna; Zirath, Hanna; Prochownik, Edward V.; Westwood, Nicholas J.; Henriksson, Marie Arsenian

    2014-01-01

    Members of the MYC family are the most frequently deregulated oncogenes in human cancer and are often correlated with aggressive disease and/or poorly differentiated tumors. Since patients with MYCN-amplified neuroblastoma have a poor prognosis, targeting MYCN using small molecule inhibitors could represent a promising therapeutic approach. We have previously demonstrated that the small molecule 10058-F4, known to bind to the c-MYC bHLHZip dimerization domain and inhibiting the c-MYC/MAX interaction, also interferes with the MYCN/MAX dimerization in vitro and imparts anti-tumorigenic effects in neuroblastoma tumor models with MYCN overexpression. Our previous work also revealed that MYCN-inhibition leads to mitochondrial dysfunction resulting in accumulation of lipid droplets in neuroblastoma cells. To expand our understanding of how small molecules interfere with MYCN, we have now analyzed the direct binding of 10058-F4, as well as three of its analogs; #474, #764 and 10058-F4(7RH), one metabolite C-m/z 232, and a structurally unrelated c-MYC inhibitor 10074-G5, to the bHLHZip domain of MYCN. We also assessed their ability to induce apoptosis, neurite outgrowth and lipid accumulation in neuroblastoma cells. Interestingly, all c-MYC binding molecules tested also bind MYCN as assayed by surface plasmon resonance. Using a proximity ligation assay, we found reduced interaction between MYCN and MAX after treatment with all molecules except for the 10058-F4 metabolite C-m/z 232 and the non-binder 10058-F4(7RH). Importantly, 10074-G5 and 10058-F4 were the most efficient in inducing neuronal differentiation and lipid accumulation in MYCN-amplified neuroblastoma cells. Together our data demonstrate MYCN-binding properties for a selection of small molecules, and provide functional information that could be of importance for future development of targeted therapies against MYCN-amplified neuroblastoma. PMID:24859015

  5. Mutations in NEK8 link multiple organ dysplasia with altered Hippo signalling and increased c-MYC expression.

    PubMed

    Frank, Valeska; Habbig, Sandra; Bartram, Malte P; Eisenberger, Tobias; Veenstra-Knol, Hermine E; Decker, Christian; Boorsma, Reinder A C; Göbel, Heike; Nürnberg, Gudrun; Griessmann, Anabel; Franke, Mareike; Borgal, Lori; Kohli, Priyanka; Völker, Linus A; Dötsch, Jörg; Nürnberg, Peter; Benzing, Thomas; Bolz, Hanno J; Johnson, Colin; Gerkes, Erica H; Schermer, Bernhard; Bergmann, Carsten

    2013-06-01

    Mutations affecting the integrity and function of cilia have been identified in various genes over the last decade accounting for a group of diseases called ciliopathies. Ciliopathies display a broad spectrum of phenotypes ranging from mild manifestations to lethal combinations of multiple severe symptoms and most of them share cystic kidneys as a common feature. Our starting point was a consanguineous pedigree with three affected fetuses showing an early embryonic phenotype with enlarged cystic kidneys, liver and pancreas and developmental heart disease. By genome-wide linkage analysis, we mapped the disease locus to chromosome 17q11 and identified a homozygous nonsense mutation in NEK8/NPHP9 that encodes a kinase involved in ciliary dynamics and cell cycle progression. Missense mutations in NEK8/NPHP9 have been identified in juvenile cystic kidney jck mice and in patients suffering from nephronophthisis (NPH), an autosomal-recessive cystic kidney disease. This work confirmed a complete loss of NEK8 expression in the affected fetuses due to nonsense-mediated decay. In cultured fibroblasts derived from these fetuses, the expression of prominent polycystic kidney disease genes (PKD1 and PKD2) was decreased, whereas the oncogene c-MYC was upregulated, providing potential explanations for the observed renal phenotype. We furthermore linked NEK8 with NPHP3, another NPH protein known to cause a very similar phenotype in case of null mutations. Both proteins interact and activate the Hippo effector TAZ. Taken together, our study demonstrates that NEK8 is essential for organ development and that the complete loss of NEK8 perturbs multiple signalling pathways resulting in a severe early embryonic phenotype. PMID:23418306

  6. c-myc copy number gains in bladder cancer detected by fluorescence in situ hybridization.

    PubMed Central

    Sauter, G.; Carroll, P.; Moch, H.; Kallioniemi, A.; Kerschmann, R.; Narayan, P.; Mihatsch, M. J.; Waldman, F. M.

    1995-01-01

    Amplification and overexpression of c-myc have been suggested as prognostic markers in human cancer. To assess the role of c-myc gene copy number alterations in bladder cancer, 87 bladder tumors were examined for c-myc aberrations by fluorescence in situ hybridization. Dual labeling hybridization with a repetitive pericentromeric probe specific for chromosome 8 and a probe for the c-myc locus (at 8q24) was performed to analyze c-myc copy number in relation to chromosome 8 copy number on a cell by cell basis. A clear-cut c-myc amplification (up to 40 to 150 copies per cell) was found in 3 tumors. There was a low level c-myc copy number increase in 32 of the remaining 84 tumors. There was no association of low level c-myc copy number increase with c-myc protein overexpression. This suggests that a c-myc gene copy number gain as detected by fluorescence in situ hybridization does not necessarily reflect a disturbed c-myc gene function but may indicate a structural chromosome 8 abnormality including gain of distal 8q. The strong association of low level c-myc (8q) gains with tumor grade (P < 0.0001), stage (P < 0.0001), chromosome polysomy (P < 0.0001), p53 protein expression (P = 0.0019), p53 deletion (P = 0.0403), and tumor cell proliferation (Ki67 labeling index; P = 0.0021) is consistent with a role of chromosome 8 alterations in bladder cancer progression. Images Figure 1 PMID:7747807

  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. Kaempferol inhibits VEGF expression and in vitro angiogenesis through a novel ERK-NFκB-cMyc-p21 pathway

    PubMed Central

    Luo, Haitao; Rankin, Gary O.; Juliano, Noelle; Jiang, Bing-Hua; Chen, Yi Charlie

    2011-01-01

    Kaempferol has been reported to reduce the risk of ovarian cancer, but the mechanism is not completely understood. In this study, we tend to expand our understanding on how kaempferol regulates VEGF expression and angiogenesis in ovarian cancer cells. We timed VEGF secretion, and studied in-vitro angiogenesis by kaempferol treatment. Gene expression was examined by qRT-PCR, ELISA, Western Blotting, or luciferase assay, and pathways were examined by manipulating genetic components with plasmid or siRNA transfection. It was found that kaempferol time-dependently inhibited VEGF secretion, and suppressed in-vitro angiogenesis. Kaempferol down-regulated ERK phosphorelation as well as NFκB and cMyc expression, but promoted p21 expression. Examination of relationship between these genes suggested a novel ERK-NFκB-cMyc-p21-VEGF pathway, which accounts for kaempferol’s angioprevention effects in ovarian cancer cells. This data supplements our comprehension of the mechanisms behind kaempferol’s biological influence in ovarian cancer cells, and better characterized kaempferol toward chemoprevention. PMID:21927533

  9. 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

  10. Expression of the c-myc oncogene under control of an immunoglobulin enhancer in E mu-myc transgenic mice.

    PubMed

    Alexander, W S; Schrader, J W; Adams, J M

    1987-04-01

    Transgenic mice bearing a cellular myc oncogene coupled to the immunoglobulin heavy-chain enhancer (E mu) exhibit perturbed B-lymphocyte development and succumb to B lymphoid tumors. To investigate how the enhancer has affected myc expression, we analyzed the structure and abundance of myc transcripts in tissues of prelymphomatous mice and in the lymphomas. Expression of the E mu-myc transgene appeared to be confined largely to B lymphoid cells, being dominant in bone marrow, spleen, and lymph nodes, with no detectable expression in T cells or other hematopoietic lineages examined. The myc transcripts initiated very predominantly at the normal myc promoters, although use of the more upstream myc promoter was accentuated and an enhancer-associated promoter may be used infrequently. The level of E mu-myc transcripts in the preneoplastic lymphoid tissues and in the E mu-myc tumors was not markedly higher than myc RNA levels in proliferating normal lymphocytes. Thus, enforced expression of structurally normal myc transcripts at only a modestly elevated level has profound biological consequences. The absence of detectable endogenous c-myc RNA in any tumor, or in preneoplastic bone marrow, supports a negative feedback model for normal c-myc regulation. PMID:3037318

  11. Reversal by RARα agonist Am580 of c-Myc-induced imbalance in RARα/RARγ expression during MMTV-Myc tumorigenesis

    PubMed Central

    2012-01-01

    Introduction Retinoic acid signaling plays key roles in embryonic development and in maintaining the differentiated status of adult tissues. Recently, the nuclear retinoic acid receptor (RAR) isotypes α, β and γ were found to play specific functions in the expansion and differentiation of the stem compartments of various tissues. For instance, RARγ appears to be involved in stem cell compartment expansion, while RARα and RARβ are implicated in the subsequent cell differentiation. We found that over-expressing c-Myc in normal mouse mammary epithelium and in a c-Myc-driven transgenic model of mammary cancer, disrupts the balance between RARγ and RARα/β in favor of RARγ. Methods The effects of c-Myc on RAR isotype expression were evaluated in normal mouse mammary epithelium, mammary tumor cells obtained from the MMTV-Myc transgenic mouse model as well as human normal immortalized breast epithelial and breast cancer cell lines. The in vivo effect of the RARα-selective agonist 4-[(5,6,7,8-tetrahydro-5,5,8,8-tetramethyl-2-naphthyl)carboxamido]benzoic acid (Am580) was examined in the MMTV-Myc mouse model of mammary tumorigenesis. Results Modulation of the RARα/β to RARγ expression in mammary glands of normal mice, oncomice, and human mammary cell lines through the alteration of RAR-target gene expression affected cell proliferation, survival and tumor growth. Treatment of MMTV-Myc mice with the RARα-selective agonist Am580 led to significant inhibition of mammary tumor growth (~90%, P<0.001), lung metastasis (P<0.01) and extended tumor latency in 63% of mice. Immunocytochemical analysis showed that in these mice, RARα responsive genes such as Cyp26A1, E-cadherin, cellular retinol-binding protein 1 (CRBP1) and p27, were up-regulated. In contrast, the mammary gland tumors of mice that responded poorly to Am580 treatment (37%) expressed significantly higher levels of RARγ. In vitro experiments indicated that the rise in RARγ was functionally linked to

  12. Differential expression of c-myc gene and c-fos gene in premalignant and malignant tissues from patients with familial polyposis coli.

    PubMed

    Sugio, K; Kurata, S; Sasaki, M; Soejima, J; Sasazuki, T

    1988-09-01

    The expression of 8 oncogenes and the structures of 19 oncogenes were analyzed in 15 adenocarcinomas (12 primary and 3 metastatic), 18 adenomatous polyps, and 18 normal colonic mucosae derived from 19 patients with familial polyposis coli. The expression of c-myc gene was most elevated in carcinoma, and moderately elevated in adenoma, compared with corresponding normal colonic mucosa. In contrast, the expression of c-fos gene was markedly decreased in all samples of adenoma and carcinoma, compared with that of normal colonic mucosa. These characteristic expression patterns of c-myc and c-fos genes were revealed not only in familial polyposis coli but also in cases of nonhereditary colon carcinoma. Structures of the 19 oncogenes were not modified in either adenoma or carcinoma, except for amplification of the c-myc gene detected in one carcinoma, but not in adenoma, from the same patient. Analyses of the amplified c-myc gene suggest that gene duplication may relate to the mechanism of gene amplification. Thus, the enhanced expression of c-myc gene in adenoma and carcinoma may reflect the proliferative activity, while the c-fos gene may be a prerequisite to stabilize the state of terminal differentiation of colonic epithelial cells. PMID:2842040

  13. Disturbance of Bcl-2, Bax, Caspase-3, Ki-67 and C-myc expression in acute and subchronic exposure to benzo(a)pyrene in cervix.

    PubMed

    Gao, Meili; Li, Yongfei; Ji, Xiaoying; Xue, Xiaochang; Chen, Lan; Feng, Guodong; Zhang, Huqin; Wang, Huichun; Shah, Walayat; Hou, Zhanwu; Kong, Yu

    2016-03-01

    Epidemiological studies have demonstrated that cigarette smoking is an important cofactor or an independent risk factor for the development of cervical cancer. Benzo(a)pyrene (BaP) is one of the most potent tobacco smoke carcinogens in tobacco smoke. BaP induced DNA damage and over expression in p53 cervical tissue of mice as demonstrated in our previous study. Here we present the findings of exposure to BaP on the expression of Bcl-2, C-myc, Ki-67, Caspase-3 and Bax genes in mouse cervix. Acute intraperitoneal administration of BaP (12.5, 25, 50, 100mg/kg body weight) to ICR female mice induced a significant increase in Bcl-2, C-myc, Ki-67 mRNA and protein level till 72h except in Bcl-2 at 24h with 12.5, 25, 50mg/kg as well as at 48h with 12.5mg/kg body weight post treatment. A significant increase was also seen in Caspase-3 and Bax mRNA and protein level with peak level at 24h and gradual decrease till 72h, however, the expression of caspase-3 increased while that of Bax decreased with increasing dose of Bap after 24h. In sub chronic intraperitoneal and oral gavage administration of BaP (2.5, 5, 10mg/kg body weight), similar significant increase was observed for all the examined genes as compared to the control and vehicle groups, however the expression of Bax decreased in a dose dependent manner. The findings of this study will help in further understanding the molecular mechanism of BaP induced carcinogenesis of cervical cancer. PMID:26709117

  14. Decline in c-myc mRNA expression but not the induction of c-fos mRNA expression is associated with differentiation of SH-SY5Y human neuroblastoma cells

    SciTech Connect

    Jalava, A.M.; Heikkilae, J.E.; Akerman, K.E.O. )

    1988-11-01

    The induction of differentiation in SH-SY5Y human neuroblastoma cells with 12-O-tetradecanoylphorbol-13-acetate (TPA) is accompanied by a rapid and a transient expression of c-fos mRNA and a down-regulation of c-myc RNA. The TPA-induced expression of c-fos mRNA was inhibited by H-7, a specific inhibitor of protein kinase C (PK-C). Dioctanoylglycerol (DiC{sub 8}) failed to induce differentiation of SH-SY5Y cells or to down-regulate c-myc mRNA but it did induce the expression of c-fos mRNA. Treatment of IMR-32 human neuroblastoma cells with TPA did not cause differentiation although c-fos mRNA was induced. Since PK-C in SH-SY5Y cells was activated by both TPA and DiC{sub 8} it is suggested that the activation of PK-C alone is not sufficient to induce differentiation in SH-SY5Y cells. The down-regulation of c-myc mRNA rather than the induction of c-fos mRNA seems to be associated with differentiation process in SH-SY5Y cells.

  15. Nickel compounds induce apoptosis in human bronchial epithelial Beas-2B cells by activation of c-Myc through ERK pathway

    SciTech Connect

    Li Qin; Suen, T.-C.; Sun Hong; Arita, Adriana; Costa, Max

    2009-03-01

    Nickel compounds are carcinogenic to humans and have been shown to alter epigenetic homeostasis. The c-Myc protein controls 15% of human genes and it has been shown that fluctuations of c-Myc protein alter global epigenetic marks. Therefore, the regulation of c-Myc by nickel ions in immortalized but not tumorigenic human bronchial epithelial Beas-2B cells was examined in this study. It was found that c-Myc protein expression was increased by nickel ions in non-tumorigenic Beas-2B and human keratinocyte HaCaT cells. The results also indicated that nickel ions induced apoptosis in Beas-2B cells. Knockout of c-Myc and its restoration in a rat cell system confirmed the essential role of c-Myc in nickel ion-induced apoptosis. Further studies in Beas-2B cells showed that nickel ion increased the c-Myc mRNA level and c-Myc promoter activity, but did not increase c-Myc mRNA and protein stability. Moreover, nickel ion upregulated c-Myc in Beas-2B cells through the MEK/ERK pathway. Collectively, the results demonstrate that c-Myc induction by nickel ions occurs via an ERK-dependent pathway and plays a crucial role in nickel-induced apoptosis in Beas-2B cells.

  16. Integrin α1β1 expression is controlled by c-MYC in colorectal cancer cells.

    PubMed

    Boudjadi, S; Carrier, J C; Groulx, J-F; Beaulieu, J-F

    2016-03-31

    The α1β1 collagen receptor is only present in a few epithelial cell types. In the intestine, it is specifically expressed in proliferating crypt cells. This integrin has been reported to be involved in various cancers where it mediates the downstream activation of the Ras/ERK proliferative pathway. We have recently shown that integrin α1β1 is present in two-thirds of colon adenocarcinomas, but the mechanism by which ITGA1 expression is regulated is not known. DNA methylation, involved in ITGA1 repression during megakaryocyte differentiation, is not the mechanism of ITGA1 regulation in colorectal cancer cells. Our in silico analysis of the ITGA1 promoter revealed two response elements for MYC, an oncogenic factor known to regulate cancer cell proliferation, invasion and migration. In situ, the expressions of both MYC and ITGA1 are localized in the lower crypt of the normal colon and correlate in 72% of the 65 analyzed colorectal cancers. MYC pharmacological inhibition or downregulation of expression with short hairpin RNA in HT29, T84 and SW480 cells resulted in reduced ITGA1 expression at both the transcript and protein levels. Chromatin immunoprecipitation assays revealed that MYC was bound to the chromatin region of the ITGA1 proximal promoter, whereas MYC overexpression enhanced ITGA1 promoter activity that was reduced with MAD co-transfection or by the disruption of the response elements. We concluded that MYC is a key regulating factor for the control of ITGA1 expression. PMID:26096932

  17. Integrin α1β1 expression is controlled by c-MYC in colorectal cancer cells

    PubMed Central

    Boudjadi, S; Carrier, J C; Groulx, J-F; Beaulieu, J-F

    2016-01-01

    The α1β1 collagen receptor is only present in a few epithelial cell types. In the intestine, it is specifically expressed in proliferating crypt cells. This integrin has been reported to be involved in various cancers where it mediates the downstream activation of the Ras/ERK proliferative pathway. We have recently shown that integrin α1β1 is present in two-thirds of colon adenocarcinomas, but the mechanism by which ITGA1 expression is regulated is not known. DNA methylation, involved in ITGA1 repression during megakaryocyte differentiation, is not the mechanism of ITGA1 regulation in colorectal cancer cells. Our in silico analysis of the ITGA1 promoter revealed two response elements for MYC, an oncogenic factor known to regulate cancer cell proliferation, invasion and migration. In situ, the expressions of both MYC and ITGA1 are localized in the lower crypt of the normal colon and correlate in 72% of the 65 analyzed colorectal cancers. MYC pharmacological inhibition or downregulation of expression with short hairpin RNA in HT29, T84 and SW480 cells resulted in reduced ITGA1 expression at both the transcript and protein levels. Chromatin immunoprecipitation assays revealed that MYC was bound to the chromatin region of the ITGA1 proximal promoter, whereas MYC overexpression enhanced ITGA1 promoter activity that was reduced with MAD co-transfection or by the disruption of the response elements. We concluded that MYC is a key regulating factor for the control of ITGA1 expression. PMID:26096932

  18. Bcl-2 and c-myc expression, cell cycle kinetics and apoptosis during the progression of chronic myelogenous leukemia from diagnosis to blastic phase.

    PubMed

    Handa, H; Hegde, U P; Kotelnikov, V M; Mundle, S D; Dong, L M; Burke, P; Rose, S; Gaskin, F; Raza, A; Preisler, H D

    1997-06-01

    Chronic myelogenous leukemia (CML) has a progressive course but little is known about the biologic characteristics of disease progression. This study was designed to assess the changes in cell proliferative characteristics, apoptosis, the expression of the bcl-2 and c-myc genes between the time of initial diagnosis and entrance into the blastic phase of the disease. We observed that the rate of cell proliferation decreased and the cell death rate did not significantly change as the disease accelerated. The level of bcl-2 expression was significantly higher in accelerated/blastic phase cells than in the chronic phase cells in the population as a whole, however, the bcl-2 expression level did not change in blast cell subpopulation. c-myc Expression was significantly higher in the blast cell subpopulation of accelerated/blastic phase than in that of earlier phases of the disease. In conclusion, the characteristics of CML cells, namely proliferation rate, c-myc and bcl-2 change during the course of the disease. It is possible that the change in c-myc expression plays a causative role in evolution of the blastic phase from the chronic phase. PMID:9279359

  19. HBXIP and LSD1 Scaffolded by lncRNA Hotair Mediate Transcriptional Activation by c-Myc.

    PubMed

    Li, Yinghui; Wang, Zhen; Shi, Hui; Li, Hang; Li, Leilei; Fang, Runping; Cai, Xiaoli; Liu, Bowen; Zhang, Xiaodong; Ye, Lihong

    2016-01-15

    c-Myc is regarded as a transcription factor, but the basis for its function remains unclear. Here, we define a long noncoding RNA (lncRNA)/protein complex that mediates the transcriptional activation by c-Myc in breast cancer cells. Among 388 c-Myc target genes in human MCF-7 breast cancer cells, we found that their promoters could be occupied by the oncoprotein HBXIP. We confirmed that the HBXIP expression correlated with expression of the c-Myc target genes cyclin A, eIF4E, and LDHA. RNAi-mediated silencing of HBXIP abolished c-Myc-mediated upregulation of these target genes. Mechanistically, HBXIP interacted directly with c-Myc through the leucine zippers and recruited the lncRNA Hotair along with the histone demethylase LSD1, for which Hotair serves as a scaffold. Silencing of HBXIP, Hotair, or LSD1 was sufficient to block c-Myc-enhanced cancer cell growth in vitro and in vivo. Taken together, our results support a model in which the HBXIP/Hotair/LSD1 complex serves as a critical effector of c-Myc in activating transcription of its target genes, illuminating long-standing questions on how c-Myc drives carcinogenesis. PMID:26719542

  20. Demonstration by real-time polymerase chain reaction that cellular DNA alkylation by novel aminoindoline compounds affects expression of the protooncogene c-myc.

    PubMed

    Nelson, Stephanie M; Ferguson, Lynnette R; Denny, William A

    2005-02-01

    Aminoindolines, analogues of the potent DNA alkylating agent seco-CBI-TMI, bind to and alkylate in the minor groove of AT-rich DNA in vitro. Here we extend the in vitro mechanism of action studies by treating cells in culture and examining the DNA binding patterns within AT-rich regions of the protooncogene locus c-myc, using a real-time polymerase chain reaction (PCR) stop assay. In addition, real-time reverse transcriptase (RT) PCR is used to examine the immediate effects of drug treatment on c-myc expression. These analyses demonstrate a concentration and time dependence for DNA alkylation at the chosen sites within the c-myc locus, as well as a prompt and significant downregulation of c-myc expression. While downregulation of this important growth regulator is likely not the only consequence of aminoindoline treatment, these studies begin to address the cellular pathways that are involved in the potent cytotoxic effects observed and provide insights for the future development of anticancer drugs of this class. PMID:15720128

  1. An avian retrovirus expressing chicken pp59c-myc possesses weak transforming activity distinct from v-myc that may be modulated by adjacent normal cell neighbors.

    PubMed Central

    Filardo, E J; Humphries, E H

    1991-01-01

    We demonstrate that EF168, an avian retrovirus that expresses the chicken pp59c-myc proto-oncogene, transforms quail embryo fibroblasts in vitro. An EF168-transformed quail clone, EF168-28, containing a single provirus, synthesizes several hundred copies of c-myc RNA and expresses elevated levels of the pp59c-myc gene product. The EF168 provirus in EF168-28 was isolated as a molecular clone, and the nucleotide sequence of its c-myc allele was confirmed as identical to that of exons 2 and 3 of the chicken c-myc proto-oncogene. Extended infection of quail embryo fibroblast cultures with EF168 induced a number of in vitro transformation-associated parameters similar to those elicited by the oncogenic v-myc-encoding retrovirus MC29, including alteration of cellular morphology, anchorage-independent growth, and induction of immortalized cell lines. Despite the fact that EF168 and MC29 shared these biological activities, further analysis revealed that EF168 initiated transformation in quail embryo fibroblasts, bone marrow, or adherent peripheral blood cultures 100- to 1,000-fold less efficiently than did MC29. Further, in contrast to MC29-induced foci, EF168 foci were smaller, morphologically diffuse, and less prominent. Analysis of newly infected cells demonstrated efficient expression of EF168 viral RNA in the absence of transformation. These differences suggest that while the pp59v-myc gene product can exert dominant transforming activity on quail embryo fibroblasts, its ability to initiate transformation is distinct from that of the pp110gag-v-myc gene product encoded by MC29 and may be suppressed by adjacent nontransformed cell neighbors. Images PMID:1942247

  2. Transcriptional Regulation of CRD-BP by c-myc

    PubMed Central

    Noubissi, Felicite K.; Nikiforov, Mikhail A.; Colburn, Nancy; Spiegelman, Vladimir S.

    2010-01-01

    The coding region determinant binding protein, CRD-BP, is a multifunctional RNA binding protein involved in different processes such as mRNA turnover, translation control, and localization. It is mostly expressed in fetal and neonatal tissues, where it regulates many transcripts essential for normal embryonic development. CRD-BP is scarce or absent in normal adult tissues but reactivated and/or overexpressed in various neoplastic and preneoplastic tumors and in most cell lines. Its expression has been associated with the most aggressive form of some cancers. CRD-BP is an important regulator of different genes including a variety of oncogenes or proto-oncogenes (c-myc, β-TrCP1, GLI1, etc.). Regulation of CRD-BP expression is critical for proper control of its targets as its overexpression may play an important role in abnormal cell proliferation, suppression of apoptosis, invasion, and metastasis. Molecular bases of the regulatory mechanisms governing CRD-BP expression are still not completely elucidated. In this article, we have identified c-myc as a novel transcriptional regulator of CRD-BP. We show that c-myc binds to CRD-BP promoter and induces its transcription. This induction of CRD-BP expression contributes to the role of c-myc in the regulation of translation, increase in cell size, and acceleration of cell cycle progression via a mechanism involving upregulation of β-TrCP1 levels and activities and accelerated degradation of PDCD4. PMID:21779431

  3. Suppression of c-myc oncogene expression by a polyamine-complexed triplex forming oligonucleotide in MCF-7 breast cancer cells.

    PubMed Central

    Thomas, T J; Faaland, C A; Gallo, M A; Thomas, T

    1995-01-01

    Polyamines are excellent stabilizers of triplex DNA. Recent studies in our laboratory revealed a remarkable structural specificity of polyamines in the induction and stabilization of triplex DNA. 1,3-Diaminopropane (DAP) showed optimum efficacy amongst a series of synthetic diamines in stabilizing triplex DNA. To utilize the potential of this finding in developing an anti-gene strategy for breast cancer, we treated MCF-7 cells with a 37mer oligonucleotide to form triplex DNA in the up-stream regulatory region of the c-myc oncogene in the presence of DAP. As individual agents, the oligonucleotide and DAP did not downregulate c-myc mRNA in the presence of estradiol. Complexation of the oligonucleotide with 2 mM DAP reduced c-myc mRNA signal by 65% at 10 microM oligonucleotide concentration. In contrast, a control oligonucleotide had no significant effect on c-myc mRNA. The expression of c-fos oncogene was not significantly altered by the triplex forming oligonucleotide (TFO). DAP was internalized within 1 h of treatment; however, it had no significant effect on the level of natural polyamines. These data indicate that selective utilization of synthetic polyamines and TFOs might be an important strategy to develop anti-gene-based therapeutic modalities for breast cancer. Images PMID:7567474

  4. SIRT1 Limits Adipocyte Hyperplasia through c-Myc Inhibition.

    PubMed

    Abdesselem, Houari; Madani, Aisha; Hani, Ahmad; Al-Noubi, Muna; Goswami, Neha; Ben Hamidane, Hisham; Billing, Anja M; Pasquier, Jennifer; Bonkowski, Michael S; Halabi, Najeeb; Dalloul, Rajaa; Sheriff, Mohamed Z; Mesaeli, Nasrin; ElRayess, Mohamed; Sinclair, David A; Graumann, Johannes; Mazloum, Nayef A

    2016-01-29

    The expansion of fat mass in the obese state is due to increased adipocyte hypertrophy and hyperplasia. The molecular mechanism that drives adipocyte hyperplasia remains unknown. The NAD(+)-dependent protein deacetylase sirtuin 1 (SIRT1), a key regulator of mammalian metabolism, maintains proper metabolic functions in many tissues, counteracting obesity. Here we report that differentiated adipocytes are hyperplastic when SIRT1 is knocked down stably in mouse 3T3-L1 preadipocytes. This phenotype is associated with dysregulated adipocyte metabolism and enhanced inflammation. We also demonstrate that SIRT1 is a key regulator of proliferation in preadipocytes. Quantitative proteomics reveal that the c-Myc pathway is altered to drive enhanced proliferation in SIRT1-silenced 3T3-L1 cells. Moreover, c-Myc is hyperacetylated, levels of p27 are reduced, and cyclin-dependent kinase 2 (CDK2) is activated upon SIRT1 reduction. Remarkably, differentiating SIRT1-silenced preadipocytes exhibit enhanced mitotic clonal expansion accompanied by reduced levels of p27 as well as elevated levels of CCAAT/enhancer-binding protein β (C/EBPβ) and c-Myc, which is also hyperacetylated. c-Myc activation and enhanced proliferation phenotype are also found to be SIRT1-dependent in proliferating mouse embryonic fibroblasts and differentiating human SW872 preadipocytes. Reducing both SIRT1 and c-Myc expression in 3T3-L1 cells simultaneously does not induce the adipocyte hyperplasia phenotype, confirming that SIRT1 controls adipocyte hyperplasia through c-Myc regulation. A better understanding of the molecular mechanisms of adipocyte hyperplasia will open new avenues toward understanding obesity. PMID:26655722

  5. SIRT1 Limits Adipocyte Hyperplasia through c-Myc Inhibition*

    PubMed Central

    Abdesselem, Houari; Madani, Aisha; Hani, Ahmad; Al-Noubi, Muna; Goswami, Neha; Ben Hamidane, Hisham; Billing, Anja M.; Pasquier, Jennifer; Bonkowski, Michael S.; Halabi, Najeeb; Dalloul, Rajaa; Sheriff, Mohamed Z.; Mesaeli, Nasrin; ElRayess, Mohamed; Sinclair, David A.; Graumann, Johannes; Mazloum, Nayef A.

    2016-01-01

    The expansion of fat mass in the obese state is due to increased adipocyte hypertrophy and hyperplasia. The molecular mechanism that drives adipocyte hyperplasia remains unknown. The NAD+-dependent protein deacetylase sirtuin 1 (SIRT1), a key regulator of mammalian metabolism, maintains proper metabolic functions in many tissues, counteracting obesity. Here we report that differentiated adipocytes are hyperplastic when SIRT1 is knocked down stably in mouse 3T3-L1 preadipocytes. This phenotype is associated with dysregulated adipocyte metabolism and enhanced inflammation. We also demonstrate that SIRT1 is a key regulator of proliferation in preadipocytes. Quantitative proteomics reveal that the c-Myc pathway is altered to drive enhanced proliferation in SIRT1-silenced 3T3-L1 cells. Moreover, c-Myc is hyperacetylated, levels of p27 are reduced, and cyclin-dependent kinase 2 (CDK2) is activated upon SIRT1 reduction. Remarkably, differentiating SIRT1-silenced preadipocytes exhibit enhanced mitotic clonal expansion accompanied by reduced levels of p27 as well as elevated levels of CCAAT/enhancer-binding protein β (C/EBPβ) and c-Myc, which is also hyperacetylated. c-Myc activation and enhanced proliferation phenotype are also found to be SIRT1-dependent in proliferating mouse embryonic fibroblasts and differentiating human SW872 preadipocytes. Reducing both SIRT1 and c-Myc expression in 3T3-L1 cells simultaneously does not induce the adipocyte hyperplasia phenotype, confirming that SIRT1 controls adipocyte hyperplasia through c-Myc regulation. A better understanding of the molecular mechanisms of adipocyte hyperplasia will open new avenues toward understanding obesity. PMID:26655722

  6. Domain-specific c-Myc ubiquitylation controls c-Myc transcriptional and apoptotic activity

    PubMed Central

    Zhang, Qin; Spears, Erick; Boone, David N.; Li, Zhaoliang; Gregory, Mark A.; Hann, Stephen R.

    2013-01-01

    The oncogenic transcription factor c-Myc causes transformation and tumorigenesis, but it can also induce apoptotic cell death. Although tumor suppressors are necessary for c-Myc to induce apoptosis, the pathways and mechanisms are unclear. To further understand how c-Myc switches from an oncogenic protein to an apoptotic protein, we examined the mechanism of p53-independent c-Myc–induced apoptosis. We show that the tumor suppressor protein ARF mediates this switch by inhibiting ubiquitylation of the c-Myc transcriptional domain (TD). Whereas TD ubiquitylation is critical for c-Myc canonical transcriptional activity and transformation, inhibition of ubiquitylation leads to the induction of the noncanonical c-Myc target gene, Egr1, which is essential for efficient c-Myc–induced p53-independent apoptosis. ARF inhibits the interaction of c-Myc with the E3 ubiquitin ligase Skp2. Overexpression of Skp2, which occurs in many human tumors, inhibits the recruitment of ARF to the Egr1 promoter, leading to inhibition of c-Myc–induced apoptosis. Therapeutic strategies could be developed to activate this intrinsic apoptotic activity of c-Myc to inhibit tumorigenesis. PMID:23277542

  7. Induction of plasmacytomas secreting antigen-specific monoclonal antibodies with a retrovirus expressing v-abl and c-myc.

    PubMed Central

    Weissinger, E M; Mischak, H; Largaespada, D A; Kaehler, D A; Mitchell, T; Smith-Gill, S J; Risser, R; Mushinski, J F

    1991-01-01

    ABL-MYC, a recombinant murine retrovirus that expresses v-abl and c-myc, rapidly induces transplantable mono- or oligoclonal plasmacytomas in BALB/c mice. To determine if the targets for transformation of this retrovirus are antigen-committed B lymphocytes and to explore this system as an alternative technique for producing antigen-specific monoclonal antibodies, plasmacytomas were induced in mice that had been immunized with two different types of immunogens, hen egg white lysozyme and sheep red blood cells. The majority of these plasmacytomas secreted immunogen-specific antibodies. Plasmacytomas induced in unimmunized mice did not react with hen egg white lysozyme or sheep red blood cells. The specific antibodies were comparable in concentration, specificity, and affinity to monoclonal antibodies obtained with conventional hybridoma technology, but, in addition to IgGs and IgMs, they included specific IgA antibodies, which are rare among splenic-derived hybridomas. Our results demonstrate that a principal target for ABL-MYC is an antigen-committed B lymphocyte. In addition this procedure provides an alternative method for the production of monoclonal antibodies, without a requirement for hetero-caryon formation by cell fusion techniques. Images PMID:1924333

  8. Expression of β-catenin and c-myc during human common bile duct development: a possible role in the morphogenesis of the common bile duct

    PubMed Central

    Guo, W.L.; Zhang, Q.; Wang, J.

    2014-01-01

    β-catenin and c-myc play important roles in the development of tissues and organs. However, little is known about their expression patterns during the development of the human common bile duct. Immunohistochemistry was used to detect β-catenin and c-myc expression in common bile duct samples from postmortem tissues of 14 premature infants and 6 spontaneously aborted fetuses. The expression of β-catenin and c-myc was also analyzed by Western blot. The samples were divided into four groups based on the stage of human fetal development: 12, 13-27, 28-37, and >37 weeks. The Image-Pro Plus v. 6.0 image analysis software was used to calculate the mean qualifying score (MQS). At fetal stages 12, 13-27, 28-37, and >37 weeks, MQS of β-catenin were 612.52±262.13, 818.38±311.73, 706.33±157.19, and 350.69±110.19, respectively. There was a significant difference in MQS among the four groups (ANOVA, P=0.0155) and between the scores at >37 and 13-27 weeks (Student-Newman-Keuls, P<0.05). At fetal stages 12, 13-27, 28-37, and >37 weeks, the MQS of c-myc were 1376.64±330.04, 1224.18±171.66, 1270.24±320.75, and 741.04±219.19, respectively. There was a significant difference in MQS among the four groups (ANOVA, P=0.0087) and between the scores at >37 and 12 weeks, >37 and 13-27 weeks, and >37 and 28-37 weeks (all P<0.05, Student-Newman-Keuls). Western blots showed that β-catenin and c-myc expression were significantly higher in fetal than in postnatal control duct tissue (P<0.05). c-myc and β-catenin are involved in the normal development of the human common bile duct. PMID:25003633

  9. YY1 and c-Myc associate in vivo in a manner that depends on c-Myc levels.

    PubMed Central

    Shrivastava, A; Yu, J; Artandi, S; Calame, K

    1996-01-01

    The c-Myc oncoprotein has previously been shown to associate with transcription regulator YY1 and to inhibit its activity. We show herein that endogenous c-Myc and YY1 associate in vivo and that changes in c-Myc levels, which accompany mitogenic stimulation or differentiation of cultured cells, affect the ratio of free to c-Myc-associated YY1. We have also investigated the mechanism by which association with c-Myc inhibits YY1's ability to regulate transcription. c-Myc does not block binding of YY1 to DNA. However, protein association studies suggest that c-Myc interferes with the ability of YY1 to contact basal transcription proteins TATA-binding protein and TFIIB. Images Fig. 1 Fig. 2 Fig. 3 Fig. 4 Fig. 5 PMID:8855231

  10. Evolution of neoplastic development in the liver of transgenic mice co-expressing c-myc and transforming growth factor-alpha.

    PubMed Central

    Santoni-Rugiu, E.; Nagy, P.; Jensen, M. R.; Factor, V. M.; Thorgeirsson, S. S.

    1996-01-01

    We have previously shown that co-expression of c-myc and transforming growth factor (TGF)-alpha as transgenes in mouse liver results in major enhancement of neoplastic development in this organ as compared with expression of either of these transgenes alone. In this report we describe in detail the progression from liver cell dysplasia to hepatocellular carcinomas (HCCs) occurring in the liver of c-myc/TGF-alpha and c-myc transgenic mice. Despite morphological similarities in the sequence of events between the two transgenic lines, the dramatic acceleration, extent, and severity of hepatic lesions in c-myc/TGF-alpha mice clearly demonstrated the synergistic effects of this transgenic combination. Although c-myc/TGF-alpha and c-myc females displayed longer latency and lower tumor incidence, the pathological changes were the same as those seen in the male mice, including the formation of HCCs, which are absent in TGF-alpha single-transgenic females. Tumors in single- and double-transgenic mice showed induction of the endogenous c-myc and TGF-alpha and, most frequently, unchanged or decreased epidermal growth factor receptor, further indicating the collaborative role of c-myc and TGF-alpha in providing a selective growth advantage to tumor cells independently of the epidermal growth factor receptor levels. To identify possible tumor precursors, we focused particularly on the dysplastic changes preceding and accompanying the appearance of preneoplastic and neoplastic lesions in the double-transgenic mice. Early on, these changes were characterized by the appearance of large dysplastic hepatocytes, mostly pericentrally, expressing high levels of TGF-alpha and uPA, as well as TGF-beta 1, particularly in apoptotic cells. After a short period of replication and expansion into the liver parenchyma, as well as penetration into the central veins, these cells underwent apoptotic cell death while preneoplastic and neoplastic lesions were forming. The peritumorous tissues also

  11. Human telomerase reverse transcriptase (hTERT) promotes gastric cancer invasion through cooperating with c-Myc to upregulate heparanase expression.

    PubMed

    Tang, Bo; Xie, Rui; Qin, Yong; Xiao, Yu-Feng; Yong, Xin; Zheng, Lei; Dong, Hui; Yang, Shi-Ming

    2016-03-01

    Human telomerase reverse transcriptase (hTERT) is a central regulator of multiple hallmarks of tumors. However, the potential roles of hTERT in tumor invasion and metastasis and the underlying molecular mechanisms remain poorly understood. Here, we found that the expression of hTERT in gastric cancer (GC) was significantly associated with an advanced TNM stage, lymphatic metastasis. Survival analysis identified hTERT as an independent prognostic factor for survival of GC patients. hTERT promoted the invasion and metastasis of GC cells by binding to c-Myc and recruiting the complex to heparanase promoter to upregulate heparanase expression. In addition, our data demonstrated that hTERT activated Wnt/β-catenin signaling to promote c-Myc expression which could in turn activate hTERT transcription and expression, suggesting a positive feedback regulation in GC progression. Consistently, c-Myc and heparanase expression was positively correlated with hTERT levels, and was also an independent predictor of metastasis and survival. Collectively, our data provide a novel molecular mechanism for hTERT in promotion of GC invasion and metastasis, and highlight the molecular etiology and clinical significance of hTERT in GC progression. Targeting hTERT may represent a new therapeutic strategy to improve therapy and survival of GC patients. PMID:26689987

  12. Human telomerase reverse transcriptase (hTERT) promotes gastric cancer invasion through cooperating with c-Myc to upregulate heparanase expression

    PubMed Central

    Tang, Bo; Xie, Rui; Qin, Yong; Xiao, Yu-Feng; Yong, Xin; Zheng, Lei; Dong, Hui; Yang, Shi-Ming

    2016-01-01

    Human telomerase reverse transcriptase (hTERT) is a central regulator of multiple hallmarks of tumors. However, the potential roles of hTERT in tumor invasion and metastasis and the underlying molecular mechanisms remain poorly understood. Here, we found that the expression of hTERT in gastric cancer (GC) was significantly associated with an advanced TNM stage, lymphatic metastasis. Survival analysis identified hTERT as an independent prognostic factor for survival of GC patients. hTERT promoted the invasion and metastasis of GC cells by binding to c-Myc and recruiting the complex to heparanase promoter to upregulate heparanase expression. In addition, our data demonstrated that hTERT activated Wnt/β-catenin signaling to promote c-Myc expression which could in turn activate hTERT transcription and expression, suggesting a positive feedback regulation in GC progression. Consistently, c-Myc and heparanase expression was positively correlated with hTERT levels, and was also an independent predictor of metastasis and survival. Collectively, our data provide a novel molecular mechanism for hTERT in promotion of GC invasion and metastasis, and highlight the molecular etiology and clinical significance of hTERT in GC progression. Targeting hTERT may represent a new therapeutic strategy to improve therapy and survival of GC patients. PMID:26689987

  13. Induction of differentiation in HL60 cells by the reduction of extrachromosomally amplified c-myc.

    PubMed Central

    Eckhardt, S G; Dai, A; Davidson, K K; Forseth, B J; Wahl, G M; Von Hoff, D D

    1994-01-01

    Oncogene amplification in tumor cells results in the overexpression of proteins that confer a growth advantage in vitro and in vivo. Amplified oncogenes can reside intrachromosomally, within homogeneously staining regions (HSRs), or extrachromosomally, within double minute chromosomes (DMs). Since previous studies have shown that low concentrations of hydroxyurea (HU) can eliminate DMs, we studied the use of HU as a gene-targeting agent in tumor cells containing extrachromosomally amplified oncogenes. In a neuroendocrine cell line (COLO 320), we have shown that HU can eliminate amplified copies of c-myc located on DMs, leading to a reduction in tumorigenicity in vitro and in vivo. To determine whether the observed reduction in tumorigenicity was due to differentiation, we next investigated whether HU could induce differentiation in HL60 cells containing extrachromosomally amplified c-myc. We compared the effects of HU, as well as two other known differentiating agents (dimethyl sulfoxide and retinoic acid), on c-myc gene copy number, c-myc expression, and differentiation in HL60 cells containing amplified c-myc genes either on DMs or HSRs. We discovered that HU and dimethyl sulfoxide reduced both c-myc gene copy number and expression and induced differentiation in cells containing c-myc amplified on DMs. These agents failed to have similar effects on HL60 cells with amplified c-myc in HSRs. By contrast, retinoic acid induced differentiation independent of the localization of amplified c-myc. These data illustrate the utility of targeting extrachromosomal DNA to modulate tumor phenotype and reveal that both HU and dimethyl sulfoxide induce differentiation in HL60 cells through DM elimination. Images PMID:8022834

  14. Association Between Amplification and Expression of C-MYC Gene and Clinicopathological Characteristics of Stomach Cancer

    PubMed Central

    Khaleghian, Malihea; Jahanzad, Issa; Shakoori, Abbas; Emami Razavi, Amirnader; Azimi, Cyrus

    2016-01-01

    Background: The incidence rate of gastric cancer in western countries has shown a remarkable decline in the recent years while it is still the most common cancer among males in Iran. The proto-oncogene MYC, located at 8q24.1, regulates almost 15% of human genes and is activated in 20% of all tumors. The amplification of MYC and overexpression of its protein product are observed in 15 - 30% of gastric neoplasias. Objectives: The objective of this study was to find the preferences of Chromogenic In Situ Hybridization (CISH) and Immunohistochemistry (IHC) in diagnosis and prognosis of gastric cancer. Patients and Methods: We studied 102 samples of gastric cancer in Iran and all the patients had undergone primary surgical resection at the Cancer Institute Hospital, Tehran University of Medical Sciences. The CISH and IHC techniques were applied for all our samples. All of the samples had adenocarcinoma gastric cancer and were selected randomly. Also, the type of study was cross sectional. The sample size was 100 patients. Results: Our data revealed that both diffuse and intestinal types of gastric cancer occurred significantly more in males than females. Our results showed that there was an indication of some correlation between grades and CISH, although the difference was not significant. Our data also showed that CISH positive patients (43%) were more frequent compared to IHC positive patients (14.7%). There was a correlation between CISH and IHC. These results revealed that there was a significant difference between grades and IHC. There was also no statistical difference between CISH amplification in diffuse and intestinal types. Conclusions: From the results, it could be concluded that for administration of the treatment of stomach cancer, and progress and prognosis of tumor, which is important for patients and clinicians, the CISH is a better and more feasible test than IHC, in regards to sensitivity and specificity. PMID:27175302

  15. Modulation of Cellular Migration and Survival by c-Myc through the Downregulation of Urokinase (uPA) and uPA Receptor▿ †

    PubMed Central

    Alfano, Daniela; Votta, Giuseppina; Schulze, Almut; Downward, Julian; Caputi, Mario; Stoppelli, Maria Patrizia; Iaccarino, Ingram

    2010-01-01

    It has been proposed that c-Myc proapoptotic activity accounts for most of its restraint of tumor formation. We established a telomerase-immortalized human epithelial cell line expressing an activatable c-Myc protein. We found that c-Myc activation induces, in addition to increased sensitivity to apoptosis, reductions in cell motility and invasiveness. Transcriptome analysis revealed that urokinase (uPA) and uPA receptor (uPAR) were strongly downregulated by c-Myc. Evidence is provided that the repression of uPA and uPAR may account for most of the antimigratory and proapoptotic activities of c-Myc. c-Myc is known to cooperate with Ras in cellular transformation. We therefore investigated if this cooperation could converge in the control of uPA/uPAR expression. We found that Ras is able to block the effects of c-Myc activation on apoptosis and cellular motility but not on cell invasiveness. Accordingly, the activation of c-Myc in the context of Ras expression had only minor influence on uPAR expression but still had a profound repressive effect on uPA expression. Thus, the differential regulation of uPA and uPAR by c-Myc and Ras correlates with the effects of these two oncoproteins on cell motility, invasiveness, and survival. In conclusion, we have discovered a novel link between c-Myc and uPA/uPAR. We propose that reductions of cell motility and invasiveness could contribute to the inhibition of tumorigenesis by c-Myc and that the regulation of uPA and uPAR expression may be a component of the ability of c-Myc to reduce motility and invasiveness. PMID:20123981

  16. Ecdysteroid promotes cell cycle progression in the Bombyx wing disc through activation of c-Myc.

    PubMed

    Moriyama, Minoru; Osanai, Kohji; Ohyoshi, Tomokazu; Wang, Hua-Bing; Iwanaga, Masashi; Kawasaki, Hideki

    2016-03-01

    Developmental switching from growth to metamorphosis in imaginal primordia is an essential process of adult body planning in holometabolous insects. Although it is disciplined by a sequential action of the ecdysteroid, molecular mechanisms linking to cell proliferation are poorly understood. In the present study, we investigated the expression control of cell cycle-related genes by the ecdysteroid using the wing disc of the final-instar larvae of the silkworm, Bombyx mori. We found that the expression level of c-myc was remarkably elevated in the post-feeding cell proliferation phase, which coincided with a small increase in ecdysteroid titer. An in vitro wing disc culture showed that supplementation of the moderate level of the ecdysteroid upregulated c-myc expression within an hour and subsequently increased the expression of cell cycle core regulators, including A-, B-, D-, and E-type cyclin genes, Cdc25 and E2F1. We demonstrated that c-myc upregulation by the ecdysteroid was not inhibited in the presence of a protein synthesis inhibitor, suggesting a possibility that the ecdysteroid directly stimulates c-myc expression. Finally, results from the administration of a c-Myc inhibitor demonstrated that c-Myc plays an essential role in 20E-inducible cell proliferation. These findings suggested a novel pathway for ecdysteroid-inducible cell proliferation in insects, and it is likely to be conserved between insects and mammals in terms of steroid hormone regulation. PMID:26696544

  17. Regulation of c-Myc ubiquitination controls chronic myelogenous leukemia initiation and progression

    PubMed Central

    Reavie, Linsey; Buckley, Shannon M.; Loizou, Evangelia; Takeishi, Shoichiro; Aranda-Orgilles, Beatriz; Ndiaye-Lobry, Delphine; Abdel-Wahab, Omar; Ibrahim, Sherif; Nakayama, Keiichi I.; Aifantis, Iannis

    2013-01-01

    The molecular mechanisms regulating leukemia-initiating cell (LIC) function are of important clinical significance. We use chronic myelogenous leukemia (CML), as a model of LIC-dependent malignancy and identify the interaction between the ubiquitin ligase Fbw7 and its substrate c-Myc as a regulator of LIC homeostasis. Deletion of Fbw7 leads to c-Myc overexpression, p53-dependent LIC-specific apoptosis and the eventual inhibition of tumor progression. Decrease of either c-Myc protein levels or attenuation of the p53 response rescues LIC activity and disease progression. Further experiments showed that Fbw7 expression is required for survival and maintenance of human CML LIC. These studies identify a ubiquitin ligase:substrate pair regulating LIC activity, suggesting that targeting of the Fbw7:c-Myc axis is an attractive therapy target in refractory CML. PMID:23518350

  18. Alterations in c-Myc phenotypes resulting from dynamin-related protein 1 (Drp1)-mediated mitochondrial fission

    PubMed Central

    Sarin, M; Wang, Y; Zhang, F; Rothermund, K; Zhang, Y; Lu, J; Sims-Lucas, S; Beer-Stolz, D; Van Houten, B E; Vockley, J; Goetzman, E S; Anthony Graves, J; Prochownik, E V

    2013-01-01

    The c-Myc (Myc) oncoprotein regulates numerous phenotypes pertaining to cell mass, survival and metabolism. Glycolysis, oxidative phosphorylation (OXPHOS) and mitochondrial biogenesis are positively controlled by Myc, with myc−/− rat fibroblasts displaying atrophic mitochondria, structural and functional defects in electron transport chain (ETC) components, compromised OXPHOS and ATP depletion. However, while Myc influences mitochondrial structure and function, it is not clear to what extent the reverse is true. To test this, we induced a state of mitochondrial hyper-fission in rat fibroblasts by de-regulating Drp1, a dynamin-like GTPase that participates in the terminal fission process. The mitochondria from these cells showed reduced mass and interconnectivity, a paucity of cristae, a marked reduction in OXPHOS and structural and functional defects in ETC Complexes I and V. High rates of abortive mitochondrial fusion were observed, likely reflecting ongoing, but ultimately futile, attempts to normalize mitochondrial mass. Cellular consequences included reduction of cell volume, ATP depletion and activation of AMP-dependent protein kinase. In response to Myc deregulation, apoptosis was significantly impaired both in the absence and presence of serum, although this could be reversed by increasing ATP levels by pharmacologic means. The current work demonstrates that enforced mitochondrial fission closely recapitulates a state of Myc deficiency and that mitochondrial integrity and function can affect Myc-regulated cellular behaviors. The low intracellular ATP levels that are frequently seen in some tumors as a result of inadequate vascular perfusion could favor tumor survival by countering the pro-apoptotic tendencies of Myc overexpression. PMID:23764851

  19. 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

  20. 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

  1. SMARCAL1 Negatively Regulates C-Myc Transcription By Altering The Conformation Of The Promoter Region

    PubMed Central

    Sharma, Tapan; Bansal, Ritu; Haokip, Dominic Thangminlen; Goel, Isha; Muthuswami, Rohini

    2015-01-01

    SMARCAL1, a member of the SWI2/SNF2 protein family, stabilizes replication forks during DNA damage. In this manuscript, we provide the first evidence that SMARCAL1 is also a transcriptional co-regulator modulating the expression of c-Myc, a transcription factor that regulates 10–15% genes in the human genome. BRG1, SMARCAL1 and RNAPII were found localized onto the c-myc promoter. When HeLa cells were serum starved, the occupancy of SMARCAL1 on the c-myc promoter increased while that of BRG1 and RNAPII decreased correlating with repression of c-myc transcription. Using Active DNA-dependent ATPase A Domain (ADAAD), the bovine homolog of SMARCAL1, we show that the protein can hydrolyze ATP using a specific region upstream of the CT element of the c-myc promoter as a DNA effector. The energy, thereby, released is harnessed to alter the conformation of the promoter DNA. We propose that SMARCAL1 negatively regulates c-myc transcription by altering the conformation of its promoter region during differentiation. PMID:26648259

  2. Increases in iPS Transcription Factor (Oct4, Sox2, c-Myc, and Klf4) Gene Expression after Modified Electroconvulsive Therapy

    PubMed Central

    Nishiguchi, Masaki; Kanazawa, Tetsufumi; Tsutsumi, Atsushi; Kaneko, Takao; Uenishi, Hiroyuki; Kawabata, Yasuo; Kawashige, Seiya; Koh, Jun; Yoneda, Hiroshi

    2015-01-01

    Objective Electroconvulsive therapy (ECT) is a reasonable option for intractable depression or schizophrenia, but a mechanism of action has not been established. One credible hypothesis is related to neural plasticity. Three genes (Oct4, Sox2, c-Myc) involved in the induction of induced pluripotent stem (iPS) cells are Wnt-target genes, which constitute a key gene group involved in neural plasticity through the TCF family. Klf4 is the other gene among Yamanaka's four transcription factors, and increases in its expression are induced by stimulation of the canonical Wnt pathway. Methods We compared the peripheral blood gene expression of the four iPS genes (Oct4, Sox2, c-Myc, and Klf4) before and after modified ECT (specifically ECT with general anesthesia) of patients with intractable depression (n=6) or schizophrenia (n=6). Using Thymatron ten times the total bilateral electrical stimulation was evoked. Results Both assessments of the symptoms demonstrated significant improvement after mECT stimulation. Expression of all four genes was confirmed to increase after initial stimulation. The gene expression levels after treatment were significantly different from the initial gene expression in all twelve cases at the following treatment stages: at the 3rd mECT for Oct4; at the 6th and 10th mECT for Sox2; and at the 3rd, 6th and 10th mECT for c-Myc. Conclusion These significant differences were not present after correction for multiple testing; however, our data have the potential to explain the molecular mechanisms of mECT from a unique perspective. Further studie should be conducted to clarify the pathophysiological involvement of iPS-inducing genes in ECT. PMID:26508965

  3. Definition of regions in human c-myc that are involved in transformation and nuclear localization.

    PubMed Central

    Stone, J; de Lange, T; Ramsay, G; Jakobovits, E; Bishop, J M; Varmus, H; Lee, W

    1987-01-01

    To study the relationship between the primary structure of the c-myc protein and some of its functional properties, we made in-frame insertion and deletion mutants of the normal human c-myc coding domain that was expressed from a retroviral promoter-enhancer. We assessed the effects of these mutations on the ability of c-myc protein to cotransform normal rat embryo cells with a mutant ras gene, induce foci in a Rat-1-derived cell line (Rat-1a), and localize in nuclei. Using the cotransformation assay, we found two regions of the protein (amino acids 105 to 143 and 321 to 439) where integrity was critical: one region (amino acids 1 to 104) that tolerated insertion and small deletion mutations, but not large deletions, and another region (amino acids 144) to 320) that was largely dispensable. Comparison with regions that were important for transformation of Rat-1a cells revealed that some are essential for both activities, but others are important for only one or the other, suggesting that the two assays require different properties of the c-myc protein. Deletion of each of three regions of the c-myc protein (amino acids 106 to 143, 320 to 368, and 370 to 412) resulted in partial cytoplasmic localization, as determined by immunofluorescence or immunoprecipitation following subcellular fractionation. Some abnormally located proteins retained transforming activity; most proteins lacking transforming activity appeared to be normally located. Images PMID:3299053

  4. RNA interference screening identifies a novel role for PCTK1/CDK16 in medulloblastoma with c-Myc amplification

    PubMed Central

    Ćwiek, Paulina; Leni, Zaira; Salm, Fabiana; Dimitrova, Valeriya; Styp-Rekowska, Beata; Chiriano, Gianpaolo; Carroll, Michael; Höland, Katrin; Djonov, Valentin; Scapozza, Leonardo; Guiry, Patrick; Arcaro, Alexandre

    2015-01-01

    Medulloblastoma (MB) is the most common malignant brain tumor in children and is associated with a poor outcome. cMYC amplification characterizes a subgroup of MB with very poor prognosis. However, there exist so far no targeted therapies for the subgroup of MB with cMYC amplification. Here we used kinome-wide RNA interference screening to identify novel kinases that may be targeted to inhibit the proliferation of c-Myc-overexpressing MB. The RNAi screen identified a set of 5 genes that could be targeted to selectively impair the proliferation of c-Myc-overexpressing MB cell lines: AKAP12 (A-kinase anchor protein), CSNK1α1 (casein kinase 1, alpha 1), EPHA7 (EPH receptor A7) and PCTK1 (PCTAIRE protein kinase 1). When using RNAi and a pharmacological inhibitor selective for PCTK1, we could show that this kinase plays a crucial role in the proliferation of MB cell lines and the activation of the mammalian target of rapamycin (mTOR) pathway. In addition, pharmacological PCTK1 inhibition reduced the expression levels of c-Myc. Finally, targeting PCTK1 selectively impaired the tumor growth of c-Myc-overexpressing MB cells in vivo. Together our data uncover a novel and crucial role for PCTK1 in the proliferation and survival of MB characterized by cMYC amplification. PMID:25402633

  5. The long intergenic non-coding RNA CCR492 functions as a let-7 competitive endogenous RNA to regulate c-Myc expression.

    PubMed

    Maldotti, Mara; Incarnato, Danny; Neri, Francesco; Krepelova, Anna; Rapelli, Stefania; Anselmi, Francesca; Parlato, Caterina; Basile, Giulia; Dettori, Daniela; Calogero, Raffaele; Oliviero, Salvatore

    2016-10-01

    In mammals the cell-cycle progression through the G1 phase is a tightly regulated process mediated by the transcriptional activation of early genes in response to mitogenic stimuli, whose dysregulation often leads to tumorigenesis. We here report the discovery by RNA-seq of cell-cycle regulated (CCR) long intergenic non-coding RNAs (lincRNAs), potentially involved in the control of the cell-cycle progression. We identified 10 novel lincRNAs expressed in response to serum treatment in mouse embryonic fibroblasts (MEFs) and in BALB/c fibroblasts, comparably to early genes. By loss-of-function experiments we found that lincRNA CCR492 is required for G1/S progression, localizes in the cell cytoplasm and contains 4 let-7 microRNA recognition elements (MREs). Mechanistically, CCR492 functions as a competing endogenous RNA (ceRNA) to antagonize the function of let-7 microRNAs, leading to the de-repression of c-Myc. Moreover, we show that ectopic expression of CCR492 along with a constitutively active H-Ras promotes cell transformation. Thus, we identified a new lincRNA expressed as an early gene in mammalian cells to regulate the cell-cycle progression by upregulating c-Myc expression. PMID:27344374

  6. Liver tumor formation by a mutant retinoblastoma protein in the transgenic mice is caused by an upregulation of c-Myc target genes

    SciTech Connect

    Wang, Bo; Hikosaka, Keisuke; Sultana, Nishat; Sharkar, Mohammad Tofael Kabir; Noritake, Hidenao; Kimura, Wataru; Wu, Yi-Xin; Kobayashi, Yoshimasa; Uezato, Tadayoshi; Miura, Naoyuki

    2012-01-06

    Highlights: Black-Right-Pointing-Pointer Fifty percent of the mutant Rb transgenic mice produced liver tumors. Black-Right-Pointing-Pointer In the tumor, Foxm1, Skp2, Bmi1 and AP-1 mRNAs were up-regulated. Black-Right-Pointing-Pointer No increase in expression of the Myc-target genes was observed in the non-tumorous liver. Black-Right-Pointing-Pointer Tumor formation depends on up-regulation of the Myc-target genes. -- Abstract: The retinoblastoma (Rb) tumor suppressor encodes a nuclear phosphoprotein that regulates cellular proliferation, apoptosis and differentiation. In order to adapt itself to these biological functions, Rb is subjected to modification cycle, phosphorylation and dephosphorylation. To directly determine the effect of phosphorylation-resistant Rb on liver development and function, we generated transgenic mice expressing phosphorylation-resistant human mutant Rb (mt-Rb) under the control of the rat hepatocyte nuclear factor-1 gene promoter/enhancer. Expression of mt-Rb in the liver resulted in macroscopic neoplastic nodules (adenomas) with {approx}50% incidence within 15 months old. Interestingly, quantitative reverse transcriptase-PCR analysis showed that c-Myc was up-regulated in the liver of mt-Rb transgenic mice irrespective of having tumor tissues or no tumor. In tumor tissues, several c-Myc target genes, Foxm1, c-Jun, c-Fos, Bmi1 and Skp2, were also up-regulated dramatically. We determined whether mt-Rb activated the Myc promoter in the HTP9 cells and demonstrated that mt-Rb acted as an inhibitor of wild-type Rb-induced repression on the Myc promoter. Our results suggest that continued upregulation of c-Myc target genes promotes the liver tumor formation after about 1 year of age.

  7. c-Myc alters substrate utilization and O-GlcNAc protein posttranslational modifications without altering cardiac function during early aortic constriction

    DOE PAGESBeta

    Ledee, Dolena; Smith, Lincoln; Bruce, Margaret; Kajimoto, Masaki; Isern, Nancy; Portman, Michael A.; Olson, Aaron K.; Bertrand, Luc

    2015-08-12

    Pressure overload cardiac hypertrophy alters substrate metabolism. Prior work showed that myocardial inactivation of c-Myc (Myc) attenuated hypertrophy and decreased expression of metabolic genes after aortic constriction. Accordingly, we hypothesize that Myc regulates substrate preferences for the citric acid cycle during pressure overload hypertrophy from transverse aortic constriction (TAC) and that these metabolic changes impact cardiac function and growth. To test this hypothesis, we subjected mice with cardiac specific, inducible Myc inactivation (MycKO-TAC) and non-transgenic littermates (Cont-TAC) to transverse aortic constriction (TAC; n=7/group). A separate group underwent sham surgery (Sham, n=5). After two weeks, function was measured in isolated workingmore » hearts along with substrate fractional contributions to the citric acid cycle by using perfusate with 13C labeled mixed fatty acids, lactate, ketone bodies and unlabeled glucose and insulin. Cardiac function was similar between groups after TAC although +dP/dT and -dP/dT trended towards improvement in MycKO-TAC versus Cont-TAC. Compared to Sham, Cont-TAC had increased free fatty acid fractional contribution with a concurrent decrease in unlabeled (predominately glucose) contribution. The changes in free fatty acid and unlabeled fractional contributions were abrogated by Myc inactivation during TAC (MycKO-TAC). Additionally, protein posttranslational modification by O-GlcNAc was significantly greater in Cont-TAC versus both Sham and MycKO-TAC. Lastly, Myc alters substrate preferences for the citric acid cycle during early pressure overload hypertrophy without negatively affecting cardiac function. Myc also affects protein posttranslational modifications by O-GlcNAc during hypertrophy.« less

  8. c-Myc alters substrate utilization and O-GlcNAc protein posttranslational modifications without altering cardiac function during early aortic constriction

    SciTech Connect

    Ledee, Dolena; Smith, Lincoln; Bruce, Margaret; Kajimoto, Masaki; Isern, Nancy; Portman, Michael A.; Olson, Aaron K.; Bertrand, Luc

    2015-08-12

    Pressure overload cardiac hypertrophy alters substrate metabolism. Prior work showed that myocardial inactivation of c-Myc (Myc) attenuated hypertrophy and decreased expression of metabolic genes after aortic constriction. Accordingly, we hypothesize that Myc regulates substrate preferences for the citric acid cycle during pressure overload hypertrophy from transverse aortic constriction (TAC) and that these metabolic changes impact cardiac function and growth. To test this hypothesis, we subjected mice with cardiac specific, inducible Myc inactivation (MycKO-TAC) and non-transgenic littermates (Cont-TAC) to transverse aortic constriction (TAC; n=7/group). A separate group underwent sham surgery (Sham, n=5). After two weeks, function was measured in isolated working hearts along with substrate fractional contributions to the citric acid cycle by using perfusate with 13C labeled mixed fatty acids, lactate, ketone bodies and unlabeled glucose and insulin. Cardiac function was similar between groups after TAC although +dP/dT and -dP/dT trended towards improvement in MycKO-TAC versus Cont-TAC. Compared to Sham, Cont-TAC had increased free fatty acid fractional contribution with a concurrent decrease in unlabeled (predominately glucose) contribution. The changes in free fatty acid and unlabeled fractional contributions were abrogated by Myc inactivation during TAC (MycKO-TAC). Additionally, protein posttranslational modification by O-GlcNAc was significantly greater in Cont-TAC versus both Sham and MycKO-TAC. Lastly, Myc alters substrate preferences for the citric acid cycle during early pressure overload hypertrophy without negatively affecting cardiac function. Myc also affects protein posttranslational modifications by O-GlcNAc during hypertrophy.

  9. Inhibitory effect of cytotoxic stilbenes related to resveratrol on the expression of the VEGF, hTERT and c-Myc genes.

    PubMed

    Martí-Centelles, Rosa; Falomir, Eva; Murga, Juan; Carda, Miguel; Marco, J Alberto

    2015-10-20

    A group of thirty-nine stilbene derivatives, prepared by means of Heck coupling reactions, has been investigated for their cytotoxicity, as well as for their ability to inhibit the production of the vascular endothelial growth factor (VEGF) and the activation of telomerase. The ability of these compounds to inhibit proliferation of two tumoral cell lines (HT-29 and MCF-7) and one non tumoral cell line (HEK-293) was first determined. Subsequently, we determined the capacity of the compounds to inhibit the secretion of VEGF in the aforementioned cell lines and to downregulate the expression of the VEGF, hTERT and c-Myc genes, the two latter involved in the control of the activation of telomerase. One of the synthetic stilbenes, (E)-4-(4-methoxystyryl)aniline, showed strong cytotoxicity and proved able to cause a marked decrease both in the secretion of VEGF and in the expression of the hTERT and c-Myc genes, in all cases at concentrations in the low nanomolar range. PMID:26402726

  10. c-Myc inhibits Ras-mediated differentiation of pheochromocytoma cells by blocking c-Jun up-regulation.

    PubMed

    Vaqué, José P; Fernández-García, Belén; García-Sanz, Pablo; Ferrandiz, Nuria; Bretones, Gabriel; Calvo, Fernando; Crespo, Piero; Marín, María C; León, Javier

    2008-02-01

    Although mutant Ras proteins were originally described as transforming oncoproteins, they induce growth arrest, senescence, and/or differentiation in many cell types. c-Myc is an oncogenic transcription factor that cooperates with Ras in cellular transformation and oncogenesis. However, the Myc-Ras relationship in cellular differentiation is largely unknown. Here, we have analyzed the effects of c-Myc on PC12-derived cells (UR61 cell line), harboring an inducible N-Ras oncogene. In these cells, Ras activation induces neuronal-like differentiation by a process involving c-Jun activation. We found that c-Myc inhibited Ras-mediated differentiation by a mechanism that involves the blockade of c-Jun induction in response to Ras signal. Accordingly, ectopically expressed c-Jun could bypass c-Myc impediment of Ras-induced differentiation and activator protein 1 activation. Interestingly, it did not rescue the proliferative arrest elicited by Ras and did not enhance the differentiation-associated apoptosis. The blockade of Ras-mediated induction of c-Jun takes place at the level of c-Jun proximal promoter. Mutational analysis revealed that c-Myc regions involved in DNA binding and transactivation are required to block differentiation and c-Jun induction. c-Myc does not seem to require Miz-1 to inhibit differentiation and block c-Jun induction. Furthermore, Max is not required for c-Myc activity, as UR61 cells lack a functional Max gene. c-Myc-inhibitory effect on the Ras/c-Jun connection is not restricted to UR61 cells as it can occur in other cell types as K562 or HEK293. In conclusion, we describe a novel interplay between c-Myc and c-Jun that controls the ability of Ras to trigger the differentiation program of pheochromocytoma cells. PMID:18314492

  11. Disruption of the CREBBP gene and decreased expression of CREB, NFκB p65, c-JUN, c-FOS, BCL2 and c-MYC suggest immune dysregulation.

    PubMed

    Torres, Leuridan Cavalcante; Kulikowski, Leslie Domenici; Ramos, Patrícia Locosque; Sugayama, Sofia Mizuko Miura; Moreira-Filho, Carlos Alberto; Carneiro-Sampaio, Magda

    2013-08-01

    Genomic aberrations in the CREBBP (CREB-binding protein - CREBBP or CBP) gene such as point mutations, small insertions or exonic copy number changes are usually associated with Rubinstein-Taybi syndrome (RTs). In this study, the disruption of the CREBBP gene on chromosome 16p13.3, as revealed by CGH-array and FISH, suggests immune dysregulation in a patient with the Rubinstein Taybi syndrome (RTs) phenotype. Further investigation with Western blot techniques demonstrated decreased expression of CREB, NFκB, c-Jun, c-Fos, BCL2 and cMyc in peripheral blood mononuclear cells, thus indicating that the CREBBP gene is essential for the normal expression of these proteins and the regulation of immune responses. PMID:23643710

  12. Repression of miR-17-5p with elevated expression of E2F-1 and c-MYC in non-metastatic hepatocellular carcinoma and enhancement of cell growth upon reversing this expression pattern

    SciTech Connect

    El Tayebi, H.M.; Omar, K.; Hegy, S.; El Maghrabi, M.; El Brolosy, M.; Hosny, K.A.; Esmat, G.; Abdelaziz, A.I.

    2013-05-10

    Highlights: •The oncogenic miR-17-5p is downregulated in non-metastatic hepatocellular carcinoma patients. •E2F-1 and c-MYC transcripts are upregulated in non-metastatic HCC patients. •miR-17-5p forced overexpression inhibited E2F-1 and c-MYC expression in HuH-7 cells. •miR-17-5p mimicking increased HuH-7 cell growth, proliferation, migration and colony formation. •miR-17-5p is responsible for HCC progression among the c-MYC/E2F-1/miR-17-5p triad members. -- Abstract: E2F-1, c-MYC, and miR-17-5p is a triad of two regulatory loops: a negative and a positive loop, where c-MYC induces the expression of E2F-1 that induces the expression of miR-17-5p which in turn reverses the expression of E2F-1 to close the loop. In this study, we investigated this triad for the first time in hepatocellular carcinoma (HCC), where miR-17-5p showed a significant down-regulation in 23 non-metastatic HCC biopsies compared to 10 healthy tissues; however, E2F-1 and c-MYC transcripts were markedly elevated. Forced over-expression of miR-17-5p in HuH-7 cells resulted in enhanced cell proliferation, growth, migration and clonogenicity with concomitant inhibition of E2F-1 and c-MYC transcripts expressions, while antagomirs of miR-17-5p reversed these events. In conclusion, this study revealed a unique pattern of expression for miR-17-5p in non-metastatic HCC patients in contrast to metastatic HCC patients. In addition we show that miR-17-5p is the key player among the triad that tumor growth and spread.

  13. c-Myc is a critical target for c/EBPalpha in granulopoiesis.

    PubMed

    Johansen, L M; Iwama, A; Lodie, T A; Sasaki, K; Felsher, D W; Golub, T R; Tenen, D G

    2001-06-01

    CCAAT/enhancer binding protein alpha (C/EBPalpha) is an integral factor in the granulocytic developmental pathway, as myeloblasts from C/EBPalpha-null mice exhibit an early block in differentiation. Since mice deficient for known C/EBPalpha target genes do not exhibit the same block in granulocyte maturation, we sought to identify additional C/EBPalpha target genes essential for myeloid cell development. To identify such genes, we used both representational difference analysis and oligonucleotide array analysis with RNA derived from a C/EBPalpha-inducible myeloid cell line. From each of these independent screens, we identified c-Myc as a C/EBPalpha negatively regulated gene. We mapped an E2F binding site in the c-Myc promoter as the cis-acting element critical for C/EBPalpha negative regulation. The identification of c-Myc as a C/EBPalpha target gene is intriguing, as it has been previously shown that down-regulation of c-Myc can induce myeloid differentiation. Here we show that stable expression of c-Myc from an exogenous promoter not responsive to C/EBPalpha-mediated down-regulation forces myeloblasts to remain in an undifferentiated state. Therefore, C/EBPalpha negative regulation of c-Myc is critical for allowing early myeloid precursors to enter a differentiation pathway. This is the first report to demonstrate that C/EBPalpha directly affects the level of c-Myc expression and, thus, the decision of myeloid blasts to enter into the granulocytic differentiation pathway. PMID:11340171

  14. c-Myc Is a Critical Target for C/EBPα in Granulopoiesis

    PubMed Central

    Johansen, Lisa M.; Iwama, Atsushi; Lodie, Tracey A.; Sasaki, Koichi; Felsher, Dean W.; Golub, Todd R.; Tenen, Daniel G.

    2001-01-01

    CCAAT/enhancer binding protein α (C/EBPα) is an integral factor in the granulocytic developmental pathway, as myeloblasts from C/EBPα-null mice exhibit an early block in differentiation. Since mice deficient for known C/EBPα target genes do not exhibit the same block in granulocyte maturation, we sought to identify additional C/EBPα target genes essential for myeloid cell development. To identify such genes, we used both representational difference analysis and oligonucleotide array analysis with RNA derived from a C/EBPα-inducible myeloid cell line. From each of these independent screens, we identified c-Myc as a C/EBPα negatively regulated gene. We mapped an E2F binding site in the c-Myc promoter as the cis-acting element critical for C/EBPα negative regulation. The identification of c-Myc as a C/EBPα target gene is intriguing, as it has been previously shown that down-regulation of c-Myc can induce myeloid differentiation. Here we show that stable expression of c-Myc from an exogenous promoter not responsive to C/EBPα-mediated down-regulation forces myeloblasts to remain in an undifferentiated state. Therefore, C/EBPα negative regulation of c-Myc is critical for allowing early myeloid precursors to enter a differentiation pathway. This is the first report to demonstrate that C/EBPα directly affects the level of c-Myc expression and, thus, the decision of myeloid blasts to enter into the granulocytic differentiation pathway. PMID:11340171

  15. NM23-H2 may play an indirect role in transcriptional activation of c-myc gene expression but does not cleave the nuclease hypersensitive element III[subscript 1

    SciTech Connect

    Dexheimer, Thomas S.; Carey, Steven S.; Zuohe, Song; Gokhale, Vijay M.; Hu, Xiaohui; Murata, Lauren B.; Maes, Estelle M.; Weichsel, Andrzej; Sun, Daekyu; Meuillet, Emmanuelle J.; Montfort, William R.; Hurley, Laurence H.

    2009-05-13

    The formation of G-quadruplex structures within the nuclease hypersensitive element (NHE) III{sub 1} region of the c-myc promoter and the ability of these structures to repress c-myc transcription have been well established. However, just how these extremely stable DNA secondary structures are transformed to activate c-myc transcription is still unknown. NM23-H2/nucleoside diphosphate kinase B has been recognized as an activator of c-myc transcription via interactions with the NHE III{sub 1} region of the c-myc gene promoter. Through the use of RNA interference, we confirmed the transcriptional regulatory role of NM23-H2. In addition, we find that further purification of NM23-H2 results in loss of the previously identified DNA strand cleavage activity, but retention of its DNA binding activity. NM23-H2 binds to both single-stranded guanine- and cytosine-rich strands of the c-myc NHE III{sub 1} and, to a lesser extent, to a random single-stranded DNA template. However, it does not bind to or cleave the NHE III{sub 1} in duplex form. Significantly, potassium ions and compounds that stabilize the G-quadruplex and i-motif structures have an inhibitory effect on NM23-H2 DNA-binding activity. Mutation of Arg{sup 88} to Ala{sup 88} (R88A) reduced both DNA and nucleotide binding but had minimal effect on the NM23-H2 crystal structure. On the basis of these data and molecular modeling studies, we have proposed a stepwise trapping-out of the NHE III{sub 1} region in a single-stranded form, thus allowing single-stranded transcription factors to bind and activate c-myc transcription. Furthermore, this model provides a rationale for how the stabilization of the G-quadruplex or i-motif structures formed within the c-myc gene promoter region can inhibit NM23-H2 from activating c-myc gene expression.

  16. Disruption of Myc-Tubulin Interaction by Hyperphosphorylation of c-Myc during Mitosis or by Constitutive Hyperphosphorylation of Mutant c-Myc in Burkitt's Lymphoma

    PubMed Central

    Niklinski, Jacek; Claassen, Gisela; Meyers, Cheryl; Gregory, Mark A.; Allegra, Carmen J.; Kaye, Frederic J.; Hann, Stephen R.; Zajac-Kaye, Maria

    2000-01-01

    Somatic mutations at Thr-58 of c-Myc have been detected in Burkitt's lymphoma (BL) tumors and have been shown to affect the transforming potential of the Myc oncoprotein. In addition, the N-terminal domain of c-Myc has been shown to interact with microtubules in vivo, and the binding of c-Myc to α-tubulin was localized to amino acids 48 to 135 within the c-Myc protein. We demonstrate that c-Myc proteins harboring a naturally occurring mutation at Thr-58 from BL cell lines have increased stability and are constitutively hyperphosphorylated, which disrupts the in vivo interaction of c-Myc with α-tubulin. In addition, we show that wild-type c-Myc–α-tubulin interactions are also disrupted during a transient mitosis-specific hyperphosphorylation of c-Myc, which resembles the constitutive hyperphosphorylation pattern of Thr-58 in BL cells. PMID:10866684

  17. The long non-coding RNA PCAT-1 promotes prostate cancer cell proliferation through cMyc.

    PubMed

    Prensner, John R; Chen, Wei; Han, Sumin; Iyer, Matthew K; Cao, Qi; Kothari, Vishal; Evans, Joseph R; Knudsen, Karen E; Paulsen, Michelle T; Ljungman, Mats; Lawrence, Theodore S; Chinnaiyan, Arul M; Feng, Felix Y

    2014-11-01

    Long non-coding RNAs (lncRNAs) represent an emerging layer of cancer biology, contributing to tumor proliferation, invasion, and metastasis. Here, we describe a role for the oncogenic lncRNA PCAT-1 in prostate cancer proliferation through cMyc. We find that PCAT-1-mediated proliferation is dependent on cMyc protein stabilization, and using expression profiling, we observed that cMyc is required for a subset of PCAT-1-induced expression changes. The PCAT-1-cMyc relationship is mediated through the post-transcriptional activity of the MYC 3' untranslated region, and we characterize a role for PCAT-1 in the disruption of MYC-targeting microRNAs. To further elucidate a role for post-transcriptional regulation, we demonstrate that targeting PCAT-1 with miR-3667-3p, which does not target MYC, is able to reverse the stabilization of cMyc by PCAT-1. This work establishes a basis for the oncogenic role of PCAT-1 in cancer cell proliferation and is the first study to implicate lncRNAs in the regulation of cMyc in prostate cancer. PMID:25425964

  18. Genetic dissimilarity between primary colorectal carcinomas and their lymph node metastases: ploidy, p53, bcl-2, and c-myc expression--a pilot study.

    PubMed

    Zalata, Khaled Refaat; Elshal, Mohamed Farouk; Foda, Abd AlRahman Mohammad; Shoma, Ashraf

    2015-08-01

    The current paradigm of metastasis proposes that rare cells within primary tumors acquire metastatic capability via sequential mutations, suggesting that metastases are genetically dissimilar from their primary tumors. This study investigated the changes in the level of expression of a well-defined panel of cell proliferation, differentiation, and apoptosis markers between the primary colorectal cancer (CRC) and the corresponding synchronous lymph node (LN) metastasis from the same patients. DNA flow cytometry and immunostaining of p53, bcl-2, and c-myc were carried out on 36 cases of CRC radical resection specimens with their corresponding LN metastases. There was very low probability that the histological patterns of primary tumors and LN metastases are independent (p < 0.001). Metastatic tumors were significantly more diffusely positive for p53 than the primary tumors (p < 0.001). Conversely, primary tumors were significantly more diffusely positive for c-myc than metastatic tumors (p = 0.011). No significant difference was found between the LNs and the primary tumors in bcl-2 positivity (p = 0.538) and DNA aneuploidy (p = 0.35), with a tendency towards negative bcl-2 and less aneuploidy in LN metastases than primary tumors. In conclusion, LN metastatic colorectal carcinomas have a tendency of being less differentiated, with a higher incidence of diffuse p53 staining, lower incidence of bcl-2 staining, and less aneuploidy in comparison to their primary counterparts suggesting a more aggressive biological behavior, which could indicate the necessity for more aggressive adjuvant therapy. PMID:25840688

  19. Cadmium Activates Multiple Signaling Pathways That Coordinately Stimulate Akt Activity to Enhance c-Myc mRNA Stability

    PubMed Central

    Tsai, Jia-Shiuan; Chao, Cheng-Han; Lin, Lih-Yuan

    2016-01-01

    Cadmium is a known environmental carcinogen. Exposure of Cd leads to the activation of several proto-oncogenes in cells. We investigated here the mechanism of c-Myc expression in hepatic cells under Cd treatment. The c-Myc protein and mRNA levels increased in dose- and time-dependent manners in HepG2 cells with Cd treatment. This increase was due to an increase in c-Myc mRNA stability. To explore the mechanism involved in enhancing the mRNA stability, several cellular signaling factors that evoked by Cd treatment were analyzed. PI3K, p38, ERK and JNK were activated by Cd. However, ERK did not participate in the Cd-induced c-Myc expression. Further analysis revealed that mTORC2 was a downstream factor of p38. PI3K, JNK and mTORC2 coordinately activated Akt. Akt was phosphorylated at Thr450 in the untreated cells. Cd treatment led to additional phosphorylation at Thr308 and Ser473. Blocking any of the three signaling factors resulted in the reduction of phosphorylation level at all three Akt sites. The activated Akt phosphorylated Foxo1 and allowed the modified protein to translocate into the cytoplasm. We conclude that Cd-induced accumulation of c-Myc requires the activation of several signaling pathways. The signals act coordinately for Akt activation and drive the Foxo1 from the nucleus to the cytoplasm. Reduction of Foxo1 in the nucleus reduces the transcription of its target genes that may affect c-Myc mRNA stability, resulting in a higher accumulation of the c-Myc proteins. PMID:26751215

  20. Analysis of secretome changes uncovers an autocrine/paracrine component in the modulation of cell proliferation and motility by c-Myc.

    PubMed

    Pocsfalvi, Gabriella; Votta, Giuseppina; De Vincenzo, Anna; Fiume, Immacolata; Raj, Delfin Albert Amal; Marra, Giancarlo; Stoppelli, Maria Patrizia; Iaccarino, Ingram

    2011-12-01

    Proteins secreted by cancer cells are a major component of tumor microenvironment. However, little is known on the impact of single oncogenic lesions on the expression of secreted proteins at early stages of tumor development. Because c-Myc overexpression is among the most frequent alterations in cancer, here we investigated the effect of sustained c-Myc expression on the secretome of a nontransformed human epithelial cell line (hT-RPE). By using a quantitative proteomic approach, we have identified 125 proteins in conditioned media of hT-RPE/MycER cells upon c-Myc induction. Analysis of the 49 proteins significantly down-regulated by c-Myc revealed a marked enrichment of factors associated with growth inhibition and cellular senescence. Accordingly, media conditioned by hT-RPE cells expressing c-Myc show an increased ability to sustain hT-RPE cellular proliferation/viability. We also find a marked down-regulation of several structural and regulatory components of the extracellular matrix (ECM), which correlates with an increased chemotactic potency of the conditioned media toward fibroblasts, a major cellular component of tumor stroma. In accordance with these data, the expression of the majority of the genes encoding proteins down-regulated in hT-RPE was significantly reduced also in colorectal adenomatous polyps, early tumors in which c-Myc is invariably overexpressed. These findings help to elucidate the significance of c-Myc overexpression at early stages of tumor development and uncover a remarkable autocrine/paracrine component in the ability of c-Myc to stimulate proliferation, sustain tumor maintenance, and modulate cell migration. PMID:22011035

  1. Helicobacter pylori γ-glutamyltranspeptidase impairs T-lymphocyte function by compromising metabolic adaption through inhibition of cMyc and IRF4 expression.

    PubMed

    Wüstner, Stefanie; Mejías-Luque, Raquel; Koch, Maximilian F; Rath, Eva; Vieth, Michael; Sieber, Stephan A; Haller, Dirk; Gerhard, Markus

    2015-01-01

    Helicobacter pylori (H. pylori) is a human-specific pathogen that has evolved to cope with the immune response elicited against the infection. We previously reported that H. pylori γ-glutamyltranspeptidase (gGT) impairs T-lymphocyte proliferation and thus might act as immune regulatory factor. In this study, we analysed the underlying mechanism and its implications for H. pylori persistence. We found that H. pylori gGT compromised T-cell proliferation, activation and effector cytokine expression by specifically depriving the extracellular space of glutamine. When assessing signalling cascades and transcription factors affected by H. pylori gGT, we found that expression of cMyc and IRF4, both required for metabolic adaptation of T-lymphocytes, was highly sensitive to extracellular glutamine levels and downregulated upon gGT treatment. Moreover, we could confirm decreased IRF4 expression in T-lymphocytes infiltrating the stomach of infected individuals. Thus, our results suggest that H. pylori gGT-mediated glutamine deprivation in the gastric mucosa may suppress T-cell function thereby contributing to bacterial persistence. PMID:25087912

  2. Gamabufotalin triggers c-Myc degradation via induction of WWP2 in multiple myeloma cells

    PubMed Central

    Wang, Chao; Deng, Sa; Zhang, Baojing; Huo, Xiaokui; Zhang, Bo; Wang, Xiaobo; Zhong, Yuping; Ma, Xiaochi

    2016-01-01

    Deciding appropriate therapy for multiple myeloma (MM) is challenging because of the occurrence of multiple chromosomal changes and the fatal nature of the disease. In the current study, gamabufotalin (GBT) was isolated from toad venom, and its tumor-specific cytotoxicity was investigated in human MM cells. We found GBT inhibited cell growth and induced apoptosis with the IC50 values <50 nM. Mechanistic studies using functional approaches identified GBT as an inhibitor of c-Myc. Further analysis showed that GBT especially evoked the ubiquitination and degradation of c-Myc protein, thereby globally repressing the expression of c-Myc target genes. GBT treatment inhibited ERK and AKT signals, while stimulating the activation of JNK cascade. An E3 ubiquitin-protein ligase, WWP2, was upregulated following JNK activation and played an important role in c-Myc ubiquitination and degradation through direct protein-protein interaction. The antitumor effect of GBT was validated in a xenograft mouse model and the suppression of MM-induced osteolysis was verified in a SCID-hu model in vivo. Taken together, our study identified the potential of GBT as a promising therapeutic agent in the treatment of MM. PMID:26894970

  3. Gamabufotalin triggers c-Myc degradation via induction of WWP2 in multiple myeloma cells.

    PubMed

    Yu, Zhenlong; Li, Tao; Wang, Chao; Deng, Sa; Zhang, Baojing; Huo, Xiaokui; Zhang, Bo; Wang, Xiaobo; Zhong, Yuping; Ma, Xiaochi

    2016-03-29

    Deciding appropriate therapy for multiple myeloma (MM) is challenging because of the occurrence of multiple chromosomal changes and the fatal nature of the disease. In the current study, gamabufotalin (GBT) was isolated from toad venom, and its tumor-specific cytotoxicity was investigated in human MM cells. We found GBT inhibited cell growth and induced apoptosis with the IC50 values <50 nM. Mechanistic studies using functional approaches identified GBT as an inhibitor of c-Myc. Further analysis showed that GBT especially evoked the ubiquitination and degradation of c-Myc protein, thereby globally repressing the expression of c-Myc target genes. GBT treatment inhibited ERK and AKT signals, while stimulating the activation of JNK cascade. An E3 ubiquitin-protein ligase, WWP2, was upregulated following JNK activation and played an important role in c-Myc ubiquitination and degradation through direct protein-protein interaction. The antitumor effect of GBT was validated in a xenograft mouse model and the suppression of MM-induced osteolysis was verified in a SCID-hu model in vivo. Taken together, our study identified the potential of GBT as a promising therapeutic agent in the treatment of MM. PMID:26894970

  4. MYU, a Target lncRNA for Wnt/c-Myc Signaling, Mediates Induction of CDK6 to Promote Cell Cycle Progression.

    PubMed

    Kawasaki, Yoshihiro; Komiya, Mimon; Matsumura, Kosuke; Negishi, Lumi; Suda, Sakiko; Okuno, Masumi; Yokota, Naoko; Osada, Tomoya; Nagashima, Takeshi; Hiyoshi, Masaya; Okada-Hatakeyama, Mariko; Kitayama, Joji; Shirahige, Katsuhiko; Akiyama, Tetsu

    2016-09-01

    Aberrant activation of Wnt/β-catenin signaling is a major driving force in colon cancer. Wnt/β-catenin signaling induces the expression of the transcription factor c-Myc, leading to cell proliferation and tumorigenesis. c-Myc regulates multiple biological processes through its ability to directly modulate gene expression. Here, we identify a direct target of c-Myc, termed MYU, and show that MYU is upregulated in most colon cancers and required for the tumorigenicity of colon cancer cells. Furthermore, we demonstrate that MYU associates with the RNA binding protein hnRNP-K to stabilize CDK6 expression and thereby promotes the G1-S transition of the cell cycle. These results suggest that the MYU/hnRNP-K/CDK6 pathway functions downstream of Wnt/c-Myc signaling and plays a critical role in the proliferation and tumorigenicity of colon cancer cells. PMID:27568568

  5. Erythropoietin activates two distinct signaling pathways required for the initiation and the elongation of c-myc

    NASA Technical Reports Server (NTRS)

    Chen, C.; Sytkowski, A. J.

    2001-01-01

    Erythropoietin (Epo) stimulation of erythroid cells results in the activation of several kinases and a rapid induction of c-myc expression. Protein kinase C is necessary for Epo up-regulation of c-myc by promoting elongation at the 3'-end of exon 1. PKCepsilon mediates this signal. We now show that Epo triggers two signaling pathways to c-myc. Epo rapidly up-regulated Myc protein in BaF3-EpoR cells. The phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002 blocked Myc up-regulation in a concentration-dependent manner but had no effect on the Epo-induced phosphorylation of ERK1 and ERK2. LY294002 also had no effect on Epo up-regulation of c-fos. MEK1 inhibitor PD98059 blocked both the c-myc and the c-fos responses to Epo. PD98059 and the PKC inhibitor H7 also blocked the phosphorylation of ERK1 and ERK2. PD98059 but not LY294002 inhibited Epo induction of ERK1 and ERK2 phosphorylation in normal erythroid cells. LY294002 blocked transcription of c-myc at exon 1. PD98059 had no effect on transcription from exon 1 but, rather, blocked Epo-induced c-myc elongation at the 3'-end of exon 1. These results identify two Epo signaling pathways to c-myc, one of which is PI3K-dependent operating on transcriptional initiation, whereas the other is mitogen-activated protein kinase-dependent operating on elongation.

  6. Metformin elicits anticancer effects through the sequential modulation of DICER and c-MYC.

    PubMed

    Blandino, Giovanni; Valerio, Mariacristina; Cioce, Mario; Mori, Federica; Casadei, Luca; Pulito, Claudio; Sacconi, Andrea; Biagioni, Francesca; Cortese, Giancarlo; Galanti, Sergio; Manetti, Cesare; Citro, Gennaro; Muti, Paola; Strano, Sabrina

    2012-01-01

    Diabetic patients treated with metformin have a reduced incidence of cancer and cancer-related mortality. Here we show that metformin affects engraftment and growth of breast cancer tumours in mice. This correlates with the induction of metabolic changes compatible with clear anticancer effects. We demonstrate that microRNA modulation underlies the anticancer metabolic actions of metformin. In fact, metformin induces DICER expression and its effects are severely impaired in DICER knocked down cells. Conversely, ectopic expression of DICER recapitulates the effects of metformin in vivo and in vitro. The microRNAs upregulated by metformin belong mainly to energy metabolism pathways. Among the messenger RNAs downregulated by metformin, we found c-MYC, IRS-2 and HIF1alpha. Downregulation of c-MYC requires AMP-activated protein kinase-signalling and mir33a upregulation by metformin. Ectopic expression of c-MYC attenuates the anticancer metabolic effects of metformin. We suggest that DICER modulation, mir33a upregulation and c-MYC targeting have an important role in the anticancer metabolic effects of metformin. PMID:22643892

  7. Promoter-binding and repression of PDGFRB by c-Myc are separable activities

    PubMed Central

    Mao, Daniel Y. L.; Barsyte-Lovejoy, Dalia; Ho, Cynthia S. W.; Watson, John D.; Stojanova, Angelina; Penn, Linda Z.

    2004-01-01

    The c-Myc transcription factor represses the mRNA expression of the platelet-derived growth factor receptor beta gene (PDGFRB). Using chromatin immunoprecipitation, we show that c-Myc binds to the proximal promoter of the PDGFRB gene in proliferating rat fibroblasts. Interestingly, mutant c-Myc proteins that are unable to repress PDGFRB gene expression, c-MycdBR and c-Mycd106-143, are still able to bind to the promoter in vivo. Hence, promoter-binding and repression of PDGFRB by c-Myc are separable activities. We also show that Myc repression of PDGFRB is not dependent on previously described or known transactivator-binding regions, suggesting Myc may be recruited to the promoter by multiple or yet unidentified transcription factors. In the presence of intact promoter-binding by Myc, trichostatin A (TSA) can block Myc repression of PDGFRB in vivo, again demonstrating that promoter-binding and repression are separable. Taken together, we hypothesize that Myc repression of PDGFRB expression occurs by a multi-step mechanism in which repression is initiated after Myc is recruited to the promoter. PMID:15226411

  8. Kinetic profiling of the c-Myc transcriptome and bioinformatic analysis of repressed gene promoters

    PubMed Central

    Yap, Chui-Sun; Peterson, Abigail L; Castellani, Gastone

    2011-01-01

    Mammalian c-Myc is a member of a small family of three related proto-oncogenic transcription factors. c-Myc has an unusually broad array of regulatory functions, which include roles in cell cycle and apoptosis, a variety of metabolic functions, cell differentiation, senescence and stem cell maintenance. c-Myc modulates the expression of a very large number of genes, but the magnitude of the majority of the regulatory effects is only two-fold or less. c-Myc can both activate and repress the promoters of its target genes. Identification of genes directly regulated by c-Myc has been an enduring question in the field. We report here microarray expression profiling of a high resolution time course of c-Myc induction, using fibroblast cells in which c-Myc activity can be modulated from null to physiological. The c-Myc transcriptome data set presented is the largest reported to date with 4,186 differentially regulated genes (1,826 upregulated, 2,360 downregulated, 1% FDR). The gene expression patterns fit well with the known biological functions of c-Myc. We describe several novel findings and present tools for further data mining. Although the mechanisms of transcriptional activation by c-Myc are well understood, how c-Myc represses an even greater number of genes remains incompletely described. One mechanism involves the binding of c-Myc to other, positively acting transcription factors and interfering with their activities. We identified rapid-response genes likely to be direct c-Myc targets and analyzed the promoters of the repressed genes to identify transcription factors that could be targets of c-Myc repression. PMID:21623162

  9. An oligomer complementary to c-myc mRNA inhibits proliferation of HL-60 promyelocytic cells and induces differentiation.

    PubMed Central

    Holt, J T; Redner, R L; Nienhuis, A W

    1988-01-01

    To study the role of a nuclear proto-oncogene in the regulation of cell growth and differentiation, we inhibited HL-60 c-myc expression with a complementary antisense oligomer. This oligomer was stable in culture and entered cells, forming an intracellular duplex. Incubation of cells with the anti-myc oligomer decreased the steady-state levels of c-myc protein by 50 to 80%, whereas a control oligomer did not significantly affect the c-myc protein concentration. Direct inhibition of c-myc expression with the anti-myc oligomer was associated with a decreased cell growth rate and an induction of myeloid differentiation. Related antisense oligomers with 2- to 12-base-pair mismatches with c-myc mRNA did not influence HL-60 cells. Thus, the effects of the antisense oligomer exhibited sequence specificity, and furthermore, these effects could be reversed by hybridization competition with another complementary oligomer. Antisense inhibition of a nuclear proto-oncogene apparently bypasses cell surface events in affecting cell proliferation and differentiation. Images PMID:3280975

  10. Enforced expression of the c-myc oncogene inhibits cell differentiation by precluding entry into a distinct predifferentiation state in G/sub 0//G/sub 1/

    SciTech Connect

    Freytag, S.O.

    1988-04-01

    A broad base of data has implicated a role for the c-myc proto-oncogene in the control of the cell cycle and cell differentiation. To further define the role of myc in these processes, the authors examined the effect of enforced myc expression on several events that are thought to be important steps leading to the terminally differentiated state: (i) the ability to arrest growth in G/sub 0//G/sub 1/, (ii) the ability to replicate the genome upon initiation of the differentiation program, and (iii) the ability to loose responsiveness to mitogens and withdraw from the cell cycle. 3T3-L1 preadipocyte cell lines expressing various levels of myc mRNA were established by transfection with a recombinant myc gene under the transcriptional control of the Rous sarcoma virus (RSV) promoter. Cells that expressed high constitutive levels of pRSV myc mRNA arrested in G/sub 0//G/sub 1/ at densities similar to those of normal cells at confluence. Upon initiation of the differentiation program, such cells traversed the cell cycle with kinetics similar to those of normal cells and subsequently arrested in G/sub 0//G/sub 1/. Thus, enforced expression of myc had no effect on the ability of cells to arrest growth in G/sub 0//G/sub 1/ or to replicate the genome upon initiation of the differentiation program. Cells were then tested for their ability to reenter the cell cycle upon exposure to high concentrations of serum and for their capacity to differentiate. In contrast to normal cells, cells expressing high constitutive levels of myc RNA reentered the cell cycle when challenged with 30% serum and failed to terminally differentiate.

  11. Triptolide suppresses proliferation, hypoxia-inducible factor-1α and c-Myc expression in pancreatic cancer cells.

    PubMed

    Ding, Xiaoling; Zhou, Xiaorong; Jiang, Bo; Zhao, Qun; Zhou, Guoxiong

    2015-09-01

    Triptolide (TL) is known to suppress the proliferation of a number of pancreatic cancer cell lines in vitro. Marked antitumor effects were also observed in a xenograft model of pancreatic cancer. Hypoxia‑inducible factor‑1α (HIF‑1α) is highly expressed in pancreatic cancer cells lines. The present study therefore tested the hypothesis that suppression of HIF‑1α is associated with the antitumor activity of TL. Quantitative polymerase chain reaction and western blot analysis were used to determine the level of gene expression. A xenograft tumor model of pancreatic cancer was established in athymic nude mice and the tumor size was measured to evaluate the outcome of TL treatment. Immunohistochemistry was used to detect the expression of HIF‑1α and vascular endothelial growth factor (VEGF), and to assess microvessel density. Microarray was used to investigate gene expression in pancreatic cancer cells following TL treatment. The expression of HIF‑1α was shown to be reduced in pancreatic cell lines following treatment with TL, and this effect occurred in a dose‑dependent manner. In a xenograft model of pancreatic cancer, reduced levels of HIF‑1α were also observed in mice that were treated with TL. Furthermore, the expression of VEGF, which is a direct target of HIF‑1α, was also suppressed, and the microvessel density of tumor tissues was consequently reduced. A microarray analysis of gene expression was performed in order to investigate the potential mechanisms underlying the antitumor activity of TL. The results showed that 11 genes, including c‑Myc, SOX9 and Ets2, were downregulated at an early stage following treatment with TL. A recent study indicated that overexpression of c‑Myc in colon cancer cells promotes increased expression of HIF‑1α and VEGF. Therefore, TL may suppress HIF‑1α through a c‑Myc‑dependent mechanism, which is involved in antitumor effects in mouse models of pancreatic cancer. PMID:26094625

  12. c-MycERTAM transgene silencing in a genetically modified human neural stem cell line implanted into MCAo rodent brain

    PubMed Central

    Stevanato, Lara; Corteling, Randolph L; Stroemer, Paul; Hope, Andrew; Heward, Julie; Miljan, Erik A; Sinden, John D

    2009-01-01

    Background The human neural stem cell line CTX0E03 was developed for the cell based treatment of chronic stroke disability. Derived from fetal cortical brain tissue, CTX0E03 is a clonal cell line that contains a single copy of the c-mycERTAM transgene delivered by retroviral infection. Under the conditional regulation by 4-hydroxytamoxifen (4-OHT), c-mycERTAM enabled large-scale stable banking of the CTX0E03 cells. In this study, we investigated the fate of this transgene following growth arrest (EGF, bFGF and 4-OHT withdrawal) in vitro and following intracerebral implantation into a mid-cerebral artery occluded (MCAo) rat brain. In vitro, 4-weeks after removing growth factors and 4-OHT from the culture medium, c-mycERTAM transgene transcription is reduced by ~75%. Furthermore, immunocytochemistry and western blotting demonstrated a concurrent decrease in the c-MycERTAM protein. To examine the transcription of the transgene in vivo, CTX0E03 cells (450,000) were implanted 4-weeks post MCAo lesion and analysed for human cell survival and c-mycERTAM transcription by qPCR and qRT-PCR, respectively. Results The results show that CTX0E03 cells were present in all grafted animal brains ranging from 6.3% to 39.8% of the total cells injected. Prior to implantation, the CTX0E03 cell suspension contained 215.7 (SEM = 13.2) copies of the c-mycERTAM transcript per cell. After implantation the c-mycERTAM transcript copy number per CTX0E03 cell had reduced to 6.9 (SEM = 3.4) at 1-week and 7.7 (SEM = 2.5) at 4-weeks. Bisulfite genomic DNA sequencing of the in vivo samples confirmed c-mycERTAM silencing occurred through methylation of the transgene promoter sequence. Conclusion In conclusion the results confirm that CTX0E03 cells downregulated c-mycERTAM transgene expression both in vitro following EGF, bFGF and 4-OHT withdrawal and in vivo following implantation in MCAo rat brain. The silencing of the c-mycERTAM transgene in vivo provides an additional safety feature of CTX0E03

  13. Decoding c-Myc networks of cell cycle and apoptosis regulated genes in a transgenic mouse model of papillary lung adenocarcinomas

    PubMed Central

    Ciribilli, Yari; Singh, Prashant; Spanel, Reinhard; Inga, Alberto; Borlak, Jürgen

    2015-01-01

    The c-Myc gene codes for a basic-helix-loop-helix-leucine zipper transcription factor protein and is reported to be frequently over-expressed in human cancers. Given that c-Myc plays an essential role in neoplastic transformation we wished to define its activity in lung cancer and therefore studied its targeted expression to respiratory epithelium in a transgenic mouse disease model. Using histological well-defined tumors, transcriptome analysis identified novel c-Myc responsive cell cycle and apoptosis genes that were validated as direct c-Myc targets using EMSA, Western blotting, gene reporter and ChIP assays. Through computational analyses c-Myc cooperating transcription factors emerged for repressed and up-regulated genes in cancer samples, namely Klf7, Gata3, Sox18, p53 and Elf5 and Cebpα, respectively. Conversely, at promoters of genes regulated in transgenic but non-carcinomatous lung tissue enriched binding sites for c-Myc, Hbp1, Hif1 were observed. Bioinformatic analysis of tumor transcriptomic data revealed regulatory gene networks and highlighted mortalin and moesin as master regulators while gene reporter and ChIP assays in the H1299 lung cancer cell line as well as cross-examination of published ChIP-sequence data of 7 human and 2 mouse cell lines provided strong evidence for the identified genes to be c-Myc targets. The clinical significance of findings was established by evaluating expression of orthologous proteins in human lung cancer. Taken collectively, a molecular circuit for c-Myc-dependent cellular transformation was identified and the network analysis broadened the perspective for molecularly targeted therapies. PMID:26427040

  14. Mad4 is regulated by a transcriptional repressor complex that contains Miz-1 and c-Myc.

    PubMed Central

    Kime, Louise; Wright, Stephanie C

    2003-01-01

    Myc and Mad family proteins are central regulators of cellular proliferation and differentiation. We show that various Mad family genes have distinct patterns of expression during the chemically induced differentiation of mouse erythroleukaemia (MEL) cells, suggesting that they each serve a different function. Mad4 RNA is highly induced and persists in terminally differentiated cells, in agreement with observations in other systems. Using reporter gene assays in stably transfected MEL cells, we show that induction of Mad4 is mediated by a 49 nt core promoter region. We demonstrate that the initiator element is required for Mad4 activation, and show that induction is associated with the loss from the initiator of a complex that contains Miz-1 and c-Myc. Miz-1 activates the Mad4 promoter in transient transfection assays, and this effect is antagonized by c-Myc. We therefore identify Mad4 as a novel target of transcriptional repression by c-Myc. These data suggest that the expression of Mad4 in proliferating undifferentiated cells is suppressed by the binding of a c-Myc-Miz-1 repressor complex at the initiator, and that the activation of Mad4 during differentiation results, at least in part, from a decrease in c-Myc-mediated repression. PMID:12418961

  15. c-Myc depletion inhibits proliferation of human tumor cells at various stages of the cell cycle

    PubMed Central

    Wang, H; Mannava, S; Grachtchouk, V; Zhuang, D; Soengas, MS; Gudkov, AV; Prochownik, EV; Nikiforov, MA

    2011-01-01

    A major role for c-Myc in the proliferation of normal cells is attributed to its ability to promote progression through G1 and into S phase of the cell cycle. The absolute requirement of c-Myc for cell cycle progression in human tumor cells has not been comprehensively addressed. In the present work, we used a lentiviral-based short hairpin RNA (shRNA) expression vector to stably reduce c-Myc expression in a large number of human tumor cell lines and in three different types of normal human cells. In all cases, cell proliferation was severely inhibited, with normal cells ultimately undergoing G0/G1 growth arrest. In contrast, tumor cells demonstrated a much more variable cell cycle response with cells from several lines accumulating in S or G2/M phases. Moreover, in some tumor lines, the phase of cell cycle arrest caused by inhibition of c-Myc could be altered by depleting tumor suppressor protein p53 or its transcriptional target p21CIP/WAF. Our data suggest that, as in the case of normal cells, c-Myc is essential for sustaining proliferation of human tumor cells. However its rate-limiting role in cell cycle control is variable and is reliant upon the status of other cell cycle regulators. PMID:17906696

  16. Poly(ADP-Ribosyl)ation Is Required to Modulate Chromatin Changes at c-MYC Promoter during Emergence from Quiescence

    PubMed Central

    Battistelli, Cecilia; Ciotti, Agnese; Amati, Paolo; Maione, Rossella

    2014-01-01

    Poly(ADP-ribosyl)ation is a post-translational modification of various proteins and participates in the regulation of chromatin structure and transcription through complex mechanisms not completely understood. We have previously shown that PARP-1, the major family member of poly(ADP-ribose)polymerases, plays an important role in the cell cycle reactivation of resting cells by regulating the expression of Immediate Early Response Genes, such as c-MYC, c-FOS, JUNB and EGR-1. In the present work we have investigated the molecular mechanisms by which the enzyme induces c-MYC transcription upon serum stimulation of quiescent cells. We show that PARP-1 is constitutively associated in vivo to a c-MYC promoter region recognized as biologically relevant for the transcriptional regulation of the gene. Moreover, we report that serum stimulation causes the prompt accumulation of ADP-ribose polymers on the same region and that this modification is required for chromatin decondensation and for the exchange of negative for positive transcriptional regulators. Finally we provide evidence that the inhibition of PARP activity along with serum stimulation impairs c-MYC induction by preventing the proper accumulation of histone H3 phosphoacetylation, a specific chromatin mark for the activation of Immediate Early Response Genes. These findings not only suggest a novel strategy by which PARP-1 regulates the transcriptional activity of promoters but also provide new information about the complex regulation of c-MYC expression, a critical determinant of the transition from quiescence to proliferation. PMID:25047032

  17. Enforced expression of the c-myc oncogene inhibits cell differentiation by precluding entry into a distinct predifferentiation state in G0/G1.

    PubMed Central

    Freytag, S O

    1988-01-01

    A broad base of data has implicated a role for the c-myc proto-oncogene in the control of the cell cycle and cell differentiation. To further define the role of myc in these processes, I examined the effect of enforced myc expression on several events that are thought to be important steps leading to the terminally differentiated state: (i) the ability to arrest growth in G0/G1, (ii) the ability to replicate the genome upon initiation of the differentiation program, and (iii) the ability to lose responsiveness to mitogens and withdraw from the cell cycle. 3T3-L1 preadipocyte cell lines expressing various levels of myc mRNA were established by transfection with a recombinant myc gene under the transcriptional control of the Rous sarcoma virus (RSV) promoter. Cells that expressed high constitutive levels of pRSVmyc mRNA arrested in G0/G1 at densities similar to those of normal cells at confluence. Upon initiation of the differentiation program, such cells traversed the cell cycle with kinetics similar to those of normal cells and subsequently arrested in G0/G1. Thus, enforced expression of myc had no effect on the ability of cells to arrest growth in G0/G1 or to replicate the genome upon initiation of the differentiation program. Cells were then tested for their ability to reenter the cell cycle upon exposure to high concentrations of serum and for their capacity to differentiate. In contrast to normal cells, cells expressing high constitutive levels of myc RNA reentered the cell cycle when challenged with 30% serum and failed to terminally differentiate. The block to differentiation could be reversed by high expression of myc antisense RNA, showing that the induced block was specifically due to enforced expression of pRSVmyc. These findings indicate that 3T3-L1 preadipocytes enter a specific state in G0/G1 after treatment with differentiation inducers, into which cells expressing high constitutive levels of myc RNA are precluded from entering. I propose that myc

  18. Cancer-associated fibroblasts promote endometrial cancer growth via activation of interleukin-6/STAT-3/c-Myc pathway

    PubMed Central

    Subramaniam, Kavita S; Omar, Intan Sofia; Kwong, Soke Chee; Mohamed, Zahurin; Woo, Yin Ling; Mat Adenan, Noor Azmi; Chung, Ivy

    2016-01-01

    Cancer-associated fibroblasts (CAFs) secrete various pro-tumorigenic cytokines, yet the role of these cytokines in the progression of endometrial cancer remains unclear. We found that CAFs isolated from human endometrial cancer (EC) tissues secreted high levels of interleukin-6 (IL-6), which promotes EC cell proliferation in vitro. Neutralizing IL-6 in CAF-conditioned media reduced (47% inhibition) while IL-6 recombinant protein increased cell proliferation (~2.4 fold) of both EC cell lines and primary cultures. IL-6 receptors (IL-6R and gp130) were expressed only in EC epithelial cells but not in CAF, indicating a one-way paracrine signaling. In the presence of CAF-conditioned media, Janus kinase/signal transducers and activators of transcription (JAK/STAT3) pathway was activated in EC cells. Treatment with JAK and STAT3 specific inhibitors, AD412 and STATTIC, respectively, significantly abrogated CAF-mediated cell proliferation, indicating the role of IL-6 activation in EC cell proliferation. We further showed that one of STAT-3 target genes, c-Myc, was highly induced in EC cells after exposure to CAF-conditioned medium at both mRNA (>105-fold vs. control) and protein level (>2-fold vs. control). EC cell proliferation was dependent on c-Myc expression, as RNAi-mediated c-Myc down-regulation led to a significant 46% reduction in cell viability when compared with scrambled control. Interestingly, CAF-conditioned media failed to promote proliferation in EC cells with reduced c-Myc expression, suggesting that CAF-mediated cell proliferation was also dependent on c-Myc expression. Subcutaneous tumor xenograft model showed that EC cells grew at least 1.4 times larger when co-injected with CAF, when compared to those injected with EC cells alone. Mice injected with EC cells with down-regulated c-Myc expression, however, showed at least 2.5 times smaller tumor compared to those in control group. Notably, there was no increase of tumor size when co-injected with CAFs

  19. Cancer-associated fibroblasts promote endometrial cancer growth via activation of interleukin-6/STAT-3/c-Myc pathway.

    PubMed

    Subramaniam, Kavita S; Omar, Intan Sofia; Kwong, Soke Chee; Mohamed, Zahurin; Woo, Yin Ling; Mat Adenan, Noor Azmi; Chung, Ivy

    2016-01-01

    Cancer-associated fibroblasts (CAFs) secrete various pro-tumorigenic cytokines, yet the role of these cytokines in the progression of endometrial cancer remains unclear. We found that CAFs isolated from human endometrial cancer (EC) tissues secreted high levels of interleukin-6 (IL-6), which promotes EC cell proliferation in vitro. Neutralizing IL-6 in CAF-conditioned media reduced (47% inhibition) while IL-6 recombinant protein increased cell proliferation (~2.4 fold) of both EC cell lines and primary cultures. IL-6 receptors (IL-6R and gp130) were expressed only in EC epithelial cells but not in CAF, indicating a one-way paracrine signaling. In the presence of CAF-conditioned media, Janus kinase/signal transducers and activators of transcription (JAK/STAT3) pathway was activated in EC cells. Treatment with JAK and STAT3 specific inhibitors, AD412 and STATTIC, respectively, significantly abrogated CAF-mediated cell proliferation, indicating the role of IL-6 activation in EC cell proliferation. We further showed that one of STAT-3 target genes, c-Myc, was highly induced in EC cells after exposure to CAF-conditioned medium at both mRNA (>105-fold vs. control) and protein level (>2-fold vs. control). EC cell proliferation was dependent on c-Myc expression, as RNAi-mediated c-Myc down-regulation led to a significant 46% reduction in cell viability when compared with scrambled control. Interestingly, CAF-conditioned media failed to promote proliferation in EC cells with reduced c-Myc expression, suggesting that CAF-mediated cell proliferation was also dependent on c-Myc expression. Subcutaneous tumor xenograft model showed that EC cells grew at least 1.4 times larger when co-injected with CAF, when compared to those injected with EC cells alone. Mice injected with EC cells with down-regulated c-Myc expression, however, showed at least 2.5 times smaller tumor compared to those in control group. Notably, there was no increase of tumor size when co-injected with CAFs

  20. The Myc negative autoregulation mechanism requires Myc-Max association and involves the c-myc P2 minimal promoter.

    PubMed Central

    Facchini, L M; Chen, S; Marhin, W W; Lear, J N; Penn, L Z

    1997-01-01

    Increasing evidence supports an important biological role for Myc in the downregulation of specific gene transcription. Recent studies suggest that c-Myc may suppress promoter activity through proteins of the basal transcription machinery. We have previously reported that Myc protein, in combination with additional cellular factors, suppresses transcription initiation from the c-myc promoter. To characterize the cis components of this Myc negative autoregulation pathway, fragments of the human c-myc promoter were inserted upstream of luciferase reporter genes and assayed for responsiveness to inducible MycER activation in Rat-1 fibroblasts. We found four- to fivefold suppression of a c-myc P2 minimal promoter fragment upon induction of wild-type MycER protein activity, while induction of a mutant MycER protein lacking amino acids 106 to 143 required for Myc autosuppression failed to elicit this response. This assay is physiologically significant, as it reflects Myc autosuppression of the endogenous c-myc gene with regard to kinetics, dose dependency, cell type specificity, and c-Myc functional domains. Analysis of mutations within the P2 minimal promoter indicated that the cis components of Myc autosuppression could not be ascribed to any known protein-binding motifs. In addition, to address the trans factors required for Myc negative autoregulation, we expressed MycEG and MaxEG leucine zipper dimerization mutants in Rat-1 cells and found that Myc-Max heterodimerization is obligatory for Myc autosuppression. Two models for the Myc autosuppression mechanism are discussed. PMID:8972190

  1. ETV6/ARG oncoprotein confers autonomous cell growth by enhancing c-Myc expression via signal transducer and activator of transcription 5 activation in the acute promyelocytic leukemia cell line HT93A.

    PubMed

    Iriyama, Noriyoshi; Hatta, Yoshihiro; Takei, Masami

    2015-01-01

    We investigated the role of ETV6/ARG fusion gene by exposing the HT93A cell line to nilotinib. HT93A cells were cultured with or without nilotinib±50 ng/mL of granulocyte colony-stimulating factor (G-CSF). Nilotinib treatment inhibited cell growth by increasing the percentage of cells in G0/G1 phase through the decrease of phosphorylated signal transducer and activator of transcription 3 (STAT3) (Y705), STAT5 (Y694) and c-Myc expression. After stimulation with G-CSF, STAT5 but not STAT3 was significantly phosphorylated in both nilotinib-treated and untreated cells. Moreover, combination therapy with nilotinib and G-CSF returned the expression level of c-Myc, cell growth and cell cycle distribution to the control level. These findings suggest that the ETV6/ARG oncoprotein contributes to autonomous cell growth by compensating for the requirement of growth factor through activating STAT5 signaling, which leads to the up-regulation of c-Myc. Our data suggest that ETV6/ARG oncoprotein is a potential target in the treatment of leukemia. PMID:25373509

  2. Guttiferone K impedes cell cycle re-entry of quiescent prostate cancer cells via stabilization of FBXW7 and subsequent c-MYC degradation.

    PubMed

    Xi, Z; Yao, M; Li, Y; Xie, C; Holst, J; Liu, T; Cai, S; Lao, Y; Tan, H; Xu, H-X; Dong, Q

    2016-01-01

    Cell cycle re-entry by quiescent cancer cells is an important mechanism for cancer progression. While high levels of c-MYC expression are sufficient for cell cycle re-entry, the modality to block c-MYC expression, and subsequent cell cycle re-entry, is limited. Using reversible quiescence rendered by serum withdrawal or contact inhibition in PTEN(null)/p53(WT) (LNCaP) or PTEN(null)/p53(mut) (PC-3) prostate cancer cells, we have identified a compound that is able to impede cell cycle re-entry through c-MYC. Guttiferone K (GUTK) blocked resumption of DNA synthesis and preserved the cell cycle phase characteristics of quiescent cells after release from the quiescence. In vehicle-treated cells, there was a rapid increase in c-MYC protein levels upon release from the quiescence. However, this increase was inhibited in the presence of GUTK with an associated acceleration in c-MYC protein degradation. The inhibitory effect of GUTK on cell cycle re-entry was significantly reduced in cells overexpressing c-MYC. The protein level of FBXW7, a subunit of E3 ubiquitin ligase responsible for degradation of c-MYC, was reduced upon the release from the quiescence. In contrast, GUTK stabilized FBXW7 protein levels during release from the quiescence. The critical role of FBXW7 was confirmed using siRNA knockdown, which impaired the inhibitory effect of GUTK on c-MYC protein levels and cell cycle re-entry. Administration of GUTK, either in vitro prior to transplantation or in vivo, suppressed the growth of quiescent prostate cancer cell xenografts. Furthermore, elevation of FBXW7 protein levels and reduction of c-MYC protein levels were found in the xenografts of GUTK-treated compared with vehicle-treated mice. Hence, we have identified a compound that is capable of impeding cell cycle re-entry by quiescent PTEN(null)/p53(WT) and PTEN(null)/p53(mut) prostate cancer cells likely by promoting c-MYC protein degradation through stabilization of FBXW7. Its usage as a clinical modality to

  3. Development of pulmonary bronchiolo-alveolar adenocarcinomas in transgenic mice overexpressing murine c- myc and epidermal growth factor in alveolar type II pneumocytes

    PubMed Central

    Ehrhardt, A; Bartels, T; Geick, A; Klocke, R; Paul, D; Halter, R

    2001-01-01

    Transgenic mouse models were established to study tumorigenesis of bronchiolo-alveolar adenocarcinomas derived from alveolar type II pneumocytes (AT-II cells). Transgenic lines expressing the murine oncogene c- myc under the control of the lung-specific surfactant protein C promoter developed multifocal bronchiolo-alveolar hyperplasias, adenomas and carcinomas respectively, whereas transgenic lines expressing a secretable form of the epidermal growth factor (IgEGF), a structural and functional homologue of transforming growth factor α (TGFα), developed hyperplasias of the alveolar epithelium. Since the oncogenes c- myc and TGFα are frequently overexpressed in human lung bronchiolo-alveolar adenocarcinomas, these mouse lines are useful as models for human lung bronchiolo-alveolar adenocarcinomas. The average life expectancies of hemizygous and homozygous c- myc transgenics were 14.25 months and 9.2 months, respectively, suggesting that a dosage effect of c- myc caused an accelerated bronchiolo-alveolar adenocarcinoma formation. First analyses of double transgenics, hemizygous for both c- myc and IgEGF, show that these mice develop bronchiolo-alveolar adenocarcinomas at the average age of 9 months, indicating that these oncogenes cooperate during the lung cancer formation. Our results demonstrate that c- myc and EGF are directly involved and cooperate with one another during formation of bronchiolo-alveolar adenocarcinomas in the lung. © 2001 Cancer Research Campaign http://www.bjcancer.com PMID:11259097

  4. Transcription profiling of lung adenocarcinomas of c-myc-transgenic mice: Identification of the c-myc regulatory gene network

    PubMed Central

    Reymann, Susanne; Borlak, Jürgen

    2008-01-01

    Background The transcriptional regulator c-Myc is the most frequently deregulated oncogene in human tumors. Targeted overexpression of this gene in mice results in distinct types of lung adenocarcinomas. By using microarray technology, alterations in the expression of genes were captured based on a female transgenic mouse model in which, indeed, c-Myc overexpression in alveolar epithelium results in the development of bronchiolo-alveolar carcinoma (BAC) and papillary adenocarcinoma (PLAC). In this study, we analyzed exclusively the promoters of induced genes by different in silico methods in order to elucidate the c-Myc transcriptional regulatory network. Results We analyzed the promoters of 361 transcriptionally induced genes with respect to c-Myc binding sites and found 110 putative binding sites in 94 promoters. Furthermore, we analyzed the flanking sequences (+/- 100 bp) around the 110 c-Myc binding sites and found Ap2, Zf5, Zic3, and E2f binding sites to be overrepresented in these regions. Then, we analyzed the promoters of 361 induced genes with respect to binding sites of other transcription factors (TFs) which were upregulated by c-Myc overexpression. We identified at least one binding site of at least one of these TFs in 220 promoters, thus elucidating a potential transcription factor network. The analysis correlated well with the significant overexpression of the TFs Atf2, Foxf1a, Smad4, Sox4, Sp3 and Stat5a. Finally, we analyzed promoters of regulated genes which where apparently not regulated by c-Myc or other c-Myc targeted TFs and identified overrepresented Oct1, Mzf1, Ppargamma, Plzf, Ets, and HmgIY binding sites when compared against control promoter background. Conclusion Our in silico data suggest a model of a transcriptional regulatory network in which different TFs act in concert upon c-Myc overexpression. We determined molecular rules for transcriptional regulation to explain, in part, the carcinogenic effect seen in mice overexpressing the c-Myc

  5. The E–Id protein axis modulates the activities of the PI3K–AKT–mTORC1–Hif1a and c-myc/p19Arf pathways to suppress innate variant TFH cell development, thymocyte expansion, and lymphomagenesis

    PubMed Central

    Miyazaki, Masaki; Miyazaki, Kazuko; Chen, Shuwen; Chandra, Vivek; Wagatsuma, Keisuke; Agata, Yasutoshi; Rodewald, Hans-Reimer; Saito, Rintaro; Chang, Aaron N.; Varki, Nissi; Kawamoto, Hiroshi

    2015-01-01

    It is now well established that the E and Id protein axis regulates multiple steps in lymphocyte development. However, it remains unknown how E and Id proteins mechanistically enforce and maintain the naïve T-cell fate. Here we show that Id2 and Id3 suppressed the development and expansion of innate variant follicular helper T (TFH) cells. Innate variant TFH cells required major histocompatibility complex (MHC) class I-like signaling and were associated with germinal center B cells. We found that Id2 and Id3 induced Foxo1 and Foxp1 expression to antagonize the activation of a TFH transcription signature. We show that Id2 and Id3 acted upstream of the Hif1a/Foxo/AKT/mTORC1 pathway as well as the c-myc/p19Arf module to control cellular expansion. We found that mice depleted for Id2 and Id3 expression developed colitis and αβ T-cell lymphomas. Lymphomas depleted for Id2 and Id3 expression displayed elevated levels of c-myc, whereas p19Arf abundance declined. Transcription signatures of Id2- and Id3-depleted lymphomas revealed similarities to genetic deficiencies associated with Burkitt lymphoma. We propose that, in response to antigen receptor and/or cytokine signaling, the E–Id protein axis modulates the activities of the PI3K–AKT–mTORC1–Hif1a and c-myc/p19Arf pathways to control cellular expansion and homeostatic proliferation. PMID:25691468

  6. The E-Id protein axis modulates the activities of the PI3K-AKT-mTORC1-Hif1a and c-myc/p19Arf pathways to suppress innate variant TFH cell development, thymocyte expansion, and lymphomagenesis.

    PubMed

    Miyazaki, Masaki; Miyazaki, Kazuko; Chen, Shuwen; Chandra, Vivek; Wagatsuma, Keisuke; Agata, Yasutoshi; Rodewald, Hans-Reimer; Saito, Rintaro; Chang, Aaron N; Varki, Nissi; Kawamoto, Hiroshi; Murre, Cornelis

    2015-02-15

    It is now well established that the E and Id protein axis regulates multiple steps in lymphocyte development. However, it remains unknown how E and Id proteins mechanistically enforce and maintain the naïve T-cell fate. Here we show that Id2 and Id3 suppressed the development and expansion of innate variant follicular helper T (TFH) cells. Innate variant TFH cells required major histocompatibility complex (MHC) class I-like signaling and were associated with germinal center B cells. We found that Id2 and Id3 induced Foxo1 and Foxp1 expression to antagonize the activation of a TFH transcription signature. We show that Id2 and Id3 acted upstream of the Hif1a/Foxo/AKT/mTORC1 pathway as well as the c-myc/p19Arf module to control cellular expansion. We found that mice depleted for Id2 and Id3 expression developed colitis and αβ T-cell lymphomas. Lymphomas depleted for Id2 and Id3 expression displayed elevated levels of c-myc, whereas p19Arf abundance declined. Transcription signatures of Id2- and Id3-depleted lymphomas revealed similarities to genetic deficiencies associated with Burkitt lymphoma. We propose that, in response to antigen receptor and/or cytokine signaling, the E-Id protein axis modulates the activities of the PI3K-AKT-mTORC1-Hif1a and c-myc/p19Arf pathways to control cellular expansion and homeostatic proliferation. PMID:25691468

  7. Farnesiferol c induces apoptosis via regulation of L11 and c-Myc with combinational potential with anticancer drugs in non-small-cell lung cancers

    PubMed Central

    Jung, Ji Hoon; Kim, Moon Joon; Lee, Hyemin; Lee, Jihyun; Kim, Jaekwang; Lee, Hyun Joo; Shin, Eun Ah; Kim, Yoon Hyeon; Kim, Bonglee; Shim, Bum Sang; Kim, Sung-Hoon

    2016-01-01

    Though Farnesiferol c (FC) has been reported to have anti-angiogenic and antitumor activity, the underlying antitumor mechanism of FC still remains unclear. Thus, in the present study, we investigated the apoptotic mechanism of FC in human H1299 and H596 non-small lung cancer cells (NSCLCs). FC significantly showed cytotoxicity, increased sub-G1 accumulation, and attenuated the expression of Bcl-2, Bcl-xL, Survivin and procaspase 3 in H1299 and H596 cells. Furthermore, FC effectively suppressed the mRNA expression of G1 arrest related genes such as Cyclin D1, E2F1 transcription factor and CDC25A by RT-PCR. Interestingly, FC inhibited the expression of c-Myc, ribosomal protein L11 (L11) and nucleolin (NCL) in H1299 and H596 cells. Of note, silencing of L11 by siRNA transfection enhanced the expression of c-Myc through a negative feedback mechanism, while c-Myc knockdown downregulated L11 in H1299 cells. Additionally, combined treatment of FC and puromycin/doxorubicin promoted the activation of caspase 9/3, and attenuated the expression of c-Myc, Cyclin D1 and CDK4 in H1299 cells compared to single treatment. Taken together, our findings suggest that FC induces apoptosis and G1 arrest via regulation of ribosomal protein L11 and c-Myc and also enhances antitumor effect of puromycin or doxorubicin in NSCLCs. PMID:27231235

  8. Farnesiferol c induces apoptosis via regulation of L11 and c-Myc with combinational potential with anticancer drugs in non-small-cell lung cancers.

    PubMed

    Jung, Ji Hoon; Kim, Moon Joon; Lee, Hyemin; Lee, Jihyun; Kim, Jaekwang; Lee, Hyun Joo; Shin, Eun Ah; Kim, Yoon Hyeon; Kim, Bonglee; Shim, Bum Sang; Kim, Sung-Hoon

    2016-01-01

    Though Farnesiferol c (FC) has been reported to have anti-angiogenic and antitumor activity, the underlying antitumor mechanism of FC still remains unclear. Thus, in the present study, we investigated the apoptotic mechanism of FC in human H1299 and H596 non-small lung cancer cells (NSCLCs). FC significantly showed cytotoxicity, increased sub-G1 accumulation, and attenuated the expression of Bcl-2, Bcl-xL, Survivin and procaspase 3 in H1299 and H596 cells. Furthermore, FC effectively suppressed the mRNA expression of G1 arrest related genes such as Cyclin D1, E2F1 transcription factor and CDC25A by RT-PCR. Interestingly, FC inhibited the expression of c-Myc, ribosomal protein L11 (L11) and nucleolin (NCL) in H1299 and H596 cells. Of note, silencing of L11 by siRNA transfection enhanced the expression of c-Myc through a negative feedback mechanism, while c-Myc knockdown downregulated L11 in H1299 cells. Additionally, combined treatment of FC and puromycin/doxorubicin promoted the activation of caspase 9/3, and attenuated the expression of c-Myc, Cyclin D1 and CDK4 in H1299 cells compared to single treatment. Taken together, our findings suggest that FC induces apoptosis and G1 arrest via regulation of ribosomal protein L11 and c-Myc and also enhances antitumor effect of puromycin or doxorubicin in NSCLCs. PMID:27231235

  9. Involvement of SIRT1 in hypoxic down-regulation of c-Myc and β-catenin and hypoxic preconditioning effect of polyphenols

    SciTech Connect

    Hong, Kyung-Soo; Park, Jun-Ik; Kim, Mi-Ju; Kim, Hak-Bong; Lee, Jae-Won; Dao, Trong Tuan; Oh, Won Keun; Kang, Chi-Dug; Kim, Sun-Hee

    2012-03-01

    SIRT1 has been found to function as a Class III deacetylase that affects the acetylation status of histones and other important cellular nonhistone proteins involved in various cellular pathways including stress responses and apoptosis. In this study, we investigated the role of SIRT1 signaling in the hypoxic down-regulations of c-Myc and β-catenin and hypoxic preconditioning effect of the red wine polyphenols such as piceatannol, myricetin, quercetin and resveratrol. We found that the expression of SIRT1 was significantly increased in hypoxia-exposed or hypoxic preconditioned HepG2 cells, which was closely associated with the up-regulation of HIF-1α and down-regulation of c-Myc and β-catenin expression via deacetylation of these proteins. In addition, blockade of SIRT1 activation using siRNA or amurensin G, a new potent SIRT1 inhibitor, abolished hypoxia-induced HIF-1α expression but increased c-Myc and β-catenin expression. SIRT1 was also found to stabilize HIF-1α protein and destabilize c-Myc, β-catenin and PHD2 under hypoxia. We also found that myricetin, quercetin, piceatannol and resveratrol up-regulated HIF-1α and down-regulated c-Myc, PHD2 and β-catenin expressions via SIRT1 activation, in a manner that mimics hypoxic preconditioning. This study provides new insights of the molecular mechanisms of hypoxic preconditioning and suggests that polyphenolic SIRT1 activators could be used to mimic hypoxic/ischemic preconditioning. -- Graphical abstract: Polyphenols mimicked hypoxic preconditioning by up-regulating HIF-1α and SIRT1 and down-regulating c-Myc, PHD2, and β-catenin. HepG2 cells were pretreated with the indicated doses of myricetin (MYR; A), quercetin (QUR; B), or piceatannol (PIC; C) for 4 h and then exposed to hypoxia for 4 h. Levels of HIF-1α, SIRT1, c-Myc, β-catenin, and PHD2 were determined by western blot analysis. The data are representative of three individual experiments. Highlights: ► SIRT1 expression is increased in hypoxia

  10. Thymidylate synthase binds to c-myc RNA in human colon cancer cells and in vitro.

    PubMed

    Chu, E; Takechi, T; Jones, K L; Voeller, D M; Copur, S M; Maley, G F; Maley, F; Segal, S; Allegra, C J

    1995-01-01

    Using an immunoprecipitation-reverse transcription-PCR technique, we characterized a thymidylate synthase (TS) ribonucleoprotein complex in cultured human colon cancer cells that consists of TS protein and the mRNA of the nuclear oncogene c-myc. TS protein is complexed in intact cells with the C-terminal coding region of c-myc mRNA that includes nucleotide positions 1625 to 1790. RNA electrophoretic gel mobility shift assays confirm a specific interaction between TS protein and c-myc mRNA and provide additional evidence that the C-terminal coding region represents an important cis-acting regulatory element. Further evidence demonstrates that the in vitro translational efficiency of c-myc mRNA is inhibited as a result of its direct interaction with TS protein. In addition, the presence of exogenous c-myc mRNA specifically relieves the inhibitory effects of TS protein on TS mRNA translation. PMID:7799924

  11. Non-transmissible Sendai virus vector encoding c-myc suppressor FBP-interacting repressor for cancer therapy

    PubMed Central

    Matsushita, Kazuyuki; Shimada, Hideaki; Ueda, Yasuji; Inoue, Makoto; Hasegawa, Mamoru; Tomonaga, Takeshi; Matsubara, Hisahiro; Nomura, Fumio

    2014-01-01

    AIM: To investigate a novel therapeutic strategy to target and suppress c-myc in human cancers using far up stream element (FUSE)-binding protein-interacting repressor (FIR). METHODS: Endogenous c-Myc suppression and apoptosis induction by a transient FIR-expressing vector was examined in vivo via a HA-tagged FIR (HA-FIR) expression vector. A fusion gene-deficient, non-transmissible, Sendai virus (SeV) vector encoding FIR cDNA, SeV/dF/FIR, was prepared. SeV/dF/FIR was examined for its gene transduction efficiency, viral dose dependency of antitumor effect and apoptosis induction in HeLa (cervical squamous cell carcinoma) cells and SW480 (colon adenocarcinoma) cells. Antitumor efficacy in a mouse xenograft model was also examined. The molecular mechanism of the anti-tumor effect and c-Myc suppression by SeV/dF/FIR was examined using Spliceostatin A (SSA), a SAP155 inhibitor, or SAP155 siRNA which induce c-Myc by increasing FIR∆exon2 in HeLa cells. RESULTS: FIR was found to repress c-myc transcription and in turn the overexpression of FIR drove apoptosis through c-myc suppression. Thus, FIR expressing vectors are potentially applicable for cancer therapy. FIR is alternatively spliced by SAP155 in cancer cells lacking the transcriptional repression domain within exon 2 (FIR∆exon2), counteracting FIR for c-Myc protein expression. Furthermore, FIR forms a complex with SAP155 and inhibits mutual well-established functions. Thus, both the valuable effects and side effects of exogenous FIR stimuli should be tested for future clinical application. SeV/dF/FIR, a cytoplasmic RNA virus, was successfully prepared and showed highly efficient gene transduction in in vivo experiments. Furthermore, in nude mouse tumor xenograft models, SeV/dF/FIR displayed high antitumor efficiency against human cancer cells. SeV/dF/FIR suppressed SSA-activated c-Myc. SAP155 siRNA, potentially produces FIR∆exon2, and led to c-Myc overexpression with phosphorylation at Ser62. HA-FIR suppressed

  12. c-Myc activates multiple metabolic networks to generate substrates for cell-cycle entry.

    SciTech Connect

    Morrish, Fionnuala M.; Isern, Nancy; Sadilek, Martin; Jeffrey, Mark; Hockenbery, David M.

    2009-05-18

    Cell proliferation requires the coordinated activity of cytosolic and mitochondrial metabolic pathways to provide ATP and building blocks for DNA, RNA, and protein synthesis. Many metabolic pathway genes are targets of the c-myc oncogene and cell cycle regulator. However, the contribution of c-Myc to the activation of cytosolic and mitochondrial metabolic networks during cell cycle entry is unknown. Here, we report the metabolic fates of [U-13C] glucose in serum-stimulated myc-/- and myc+/+ fibroblasts by 13C isotopomer NMR analysis. We demonstrate that endogenous c-myc increased 13C-labeling of ribose sugars, purines, and amino acids, indicating partitioning of glucose carbons into C1/folate and pentose phosphate pathways, and increased tricarboxylic acid cycle turnover at the expense of anaplerotic flux. Myc expression also increased global O-linked GlcNAc protein modification, and inhibition of hexosamine biosynthesis selectively reduced growth of Myc-expressing cells, suggesting its importance in Myc-induced proliferation. These data reveal a central organizing role for the Myc oncogene in the metabolism of cycling cells. The pervasive deregulation of this oncogene in human cancers may be explained by its role in directing metabolic networks required for cell proliferation.

  13. Cholesteryl butyrate solid lipid nanoparticles as a butyric acid pro-drug: effects on cell proliferation, cell-cycle distribution and c-myc expression in human leukemic cells.

    PubMed

    Serpe, Loredana; Laurora, Stefano; Pizzimenti, Stefania; Ugazio, Elena; Ponti, Renata; Canaparo, Roberto; Briatore, Federica; Barrera, Giuseppina; Gasco, Maria Rosa; Bernengo, Maria Grazia; Eandi, Mario; Zara, Gian Paolo

    2004-06-01

    Cholesteryl butyrate solid lipid nanoparticles (chol-but SLN) have been proposed as a pro-drug to deliver butyric acid. We compared the effects on cell growth, cell-cycle distribution and c-myc expression of chol-but SLN and sodium butyrate (Na-but) in the human leukemic cell lines Jurkat, U937 and HL-60. In all the cell lines 0.5 and 1.0 mM chol-but SLN provoked a complete block of cell growth. Cell-cycle analysis demonstrated in Jurkat cells that 0.25 mM chol-but SLN caused a pronounced increase of G2/M cells and a decrease of G0/G1 cells, whereas in U937 and HL-60 cells chol-but SLN led to a dose-dependent increase of G0/G1 cells, with a decrease of G2/M cells. In Jurkat and HL-60 cells 0.5 mM chol-but SLN induced a significant increase of sub-G0/G1 apoptotic cells. Cell growth and cell-cycle distribution were unaffected by the same concentrations of Na-but. A concentration of 0.25 mM chol-but SLN was able to cause a rapid and transient down-regulation of c-myc expression in all the cell lines, whereas 1 mM Na-but caused a slight reduction of c-myc expression only in U937 cells. The results show how chol-but SLN affects the proliferation pattern of both myeloid and lymphoid cells to an extent greater than the natural butyrate. PMID:15166628

  14. The cytoplasmic Purkinje onconeural antigen cdr2 down-regulates c-Myc function: implications for neuronal and tumor cell survival

    PubMed Central

    Okano, Hirotaka J.; Park, Woong-Y.; Corradi, John P.; Darnell, Robert B.

    1999-01-01

    Paraneoplastic cerebellar degeneration (PCD) is a disorder in which breast or ovarian tumors express an onconeural antigen termed cdr2, which normally is expressed in cerebellar Purkinje neurons. This leads to an immune response to cdr2 that is associated with tumor immunity and autoimmune cerebellar degeneration. We have found that cdr2, a cytoplasmic protein harboring a helix–leucine zipper (HLZ) motif, interacts specifically with the HLZ motif of c-Myc. Both proteins colocalize in the cytoplasm of adult cerebellar Purkinje neurons, and coimmunoprecipitate from tumor cell lines and cerebellar extracts. cdr2 down–regulates c-Myc-dependent transcription in cotransfection assays, and redistributes Myc protein in the cytoplasm. Disease antisera from six of six PCD patients specifically blocked the interaction between cdr2 and c-Myc in vitro. These data indicate that cdr2 normally sequesters c-Myc in the neuronal cytoplasm, thereby down-regulating c-Myc activity, and suggest a mechanism whereby inhibition of cdr2 function by autoantibodies in PCD may contribute to Purkinje neuronal death. PMID:10465786

  15. Antiproliferative Effects of Cucurbitacin B in Breast Cancer Cells: Down-Regulation of the c-Myc/hTERT/Telomerase Pathway and Obstruction of the Cell Cycle

    PubMed Central

    Duangmano, Suwit; Dakeng, Sumana; Jiratchariyakul, Weena; Suksamrarn, Apichart; Smith, Duncan R.; Patmasiriwat, Pimpicha

    2010-01-01

    Naturally occurring cucurbitacins have been shown to have anticancer, antimicrobial and anti-inflammatory activities. In this study, we determined the effects of cucurbitacin B extracted from the Thai herb Trichosanthes cucumerina L. on telomerase regulation in three human breast cancer cell lines (T47D, SKBR-3, and MCF-7) and a mammary epithelium cell line (HBL-100). Cell viability after treatment with cucurbitacin B, which is an active ingredient of this herb, was assessed. Telomeric Repeat Amplification Protocol (TRAP) assays and RT-PCR (qualitative and realtime) were performed to investigate activity of telomerase as well as expression of human telomerase reverse transcriptase (hTERT) and c-Myc. The c-Myc protein level was also determined in SKBR-3 and HBL-100 cells. Our results show that the cucurbitacin B inhibits growth and telomerase activity in the three breast cancer cell lines and exerts an obvious inhibitory effect in the estrogen receptor (ER)-negative breast cancer SKBR-3 cells. The expression of hTERT and c-Myc were also inhibited by cucurbitacin B, In addition, a clear reduction of c-Myc protein was observed after treatment in SKBR-3 cells even with a concentration of cucurbitacin B that was ten-times lower compared to the concentration used for HBL-100. Our findings imply that cucurbitacin B exerts an anticancer effect by inhibiting telomerase via down regulating both the hTERT and c-Myc expression in breast cancer cells. PMID:21614210

  16. Antiproliferative effects of cucurbitacin B in breast cancer cells: down-regulation of the c-Myc/hTERT/telomerase pathway and obstruction of the cell cycle.

    PubMed

    Duangmano, Suwit; Dakeng, Sumana; Jiratchariyakul, Weena; Suksamrarn, Apichart; Smith, Duncan R; Patmasiriwat, Pimpicha

    2010-01-01

    Naturally occurring cucurbitacins have been shown to have anticancer, antimicrobial and anti-inflammatory activities. In this study, we determined the effects of cucurbitacin B extracted from the Thai herb Trichosanthes cucumerina L. on telomerase regulation in three human breast cancer cell lines (T47D, SKBR-3, and MCF-7) and a mammary epithelium cell line (HBL-100). Cell viability after treatment with cucurbitacin B, which is an active ingredient of this herb, was assessed. Telomeric Repeat Amplification Protocol (TRAP) assays and RT-PCR (qualitative and realtime) were performed to investigate activity of telomerase as well as expression of human telomerase reverse transcriptase (hTERT) and c-Myc. The c-Myc protein level was also determined in SKBR-3 and HBL-100 cells. Our results show that the cucurbitacin B inhibits growth and telomerase activity in the three breast cancer cell lines and exerts an obvious inhibitory effect in the estrogen receptor (ER)-negative breast cancer SKBR-3 cells. The expression of hTERT and c-Myc were also inhibited by cucurbitacin B, In addition, a clear reduction of c-Myc protein was observed after treatment in SKBR-3 cells even with a concentration of cucurbitacin B that was ten-times lower compared to the concentration used for HBL-100. Our findings imply that cucurbitacin B exerts an anticancer effect by inhibiting telomerase via down regulating both the hTERT and c-Myc expression in breast cancer cells. PMID:21614210

  17. Regulation of cancer cell death by a novel compound, C604, in a c-Myc-overexpressing cellular environment.

    PubMed

    Jo, Mun Jeong; Paek, A Rome; Choi, Ji Seung; Ok, Chang Youp; Jeong, Kyung Chae; Lim, Jae Hyang; Kim, Seok Hyun; You, Hye Jin

    2015-12-15

    The proto-oncogene c-Myc has been implicated in a variety of cellular processes, such as proliferation, differentiation and apoptosis. Several c-Myc targets have been studied; however, selective regulation of c-Myc is not easy in cancer cells. Herein, we attempt to identify chemical compounds that induce cell death in c-Myc-overexpressing cells (STF-cMyc and STF-Control) by conducting MTS assays on approximately 4000 chemical compounds. One compound, C604, induced cell death in STF-cMyc cells but not STF-Control cells. Apoptotic proteins, including caspase-3 and poly(ADP-ribose) polymerase (PARP), were cleaved in C604-treated STF-cMyc cells. In addition, SW620, HCT116 and NCI-H23 cells, which exhibit higher basal levels of c-Myc, underwent apoptotic cell death in response to C604, suggesting a role for C604 as an inducer of apoptosis in cancer cells with c-Myc amplification. C604 induced cell cycle arrest at the G2/M phase in cells, which was not affected by apoptotic inhibitors. Interestingly, C604 induced accumulation of c-Myc and Cdc25A proteins. In summary, a chemical compound was identified that may induce cell death in cancer cells with c-Myc amplification specifically through an apoptotic pathway. PMID:26607468

  18. c-MYC-Induced Genomic Instability

    PubMed Central

    Kuzyk, Alexandra; Mai, Sabine

    2014-01-01

    MYC dysregulation initiates a dynamic process of genomic instability that is linked to tumor initiation. Early studies using MYC-carrying retroviruses showed that these viruses were potent transforming agents. Cell culture models followed that addressed the role of MYC in transformation. With the advent of MYC transgenic mice, it became obvious that MYC deregulation alone was sufficient to initiate B-cell neoplasia in mice. More than 70% of all tumors have some form of c-MYC gene dysregulation, which affects gene regulation, microRNA expression profiles, large genomic amplifications, and the overall organization of the nucleus. These changes set the stage for the dynamic genomic rearrangements that are associated with cellular transformation. PMID:24692190

  19. c-Myc is targeted to the proteasome for degradation in a SUMOylation-dependent manner, regulated by PIAS1, SENP7 and RNF4.

    PubMed

    González-Prieto, Román; Cuijpers, Sabine Ag; Kumar, Ramesh; Hendriks, Ivo A; Vertegaal, Alfred Co

    2015-01-01

    c-Myc is the most frequently overexpressed oncogene in tumors, including breast cancer, colon cancer and lung cancer. Post-translational modifications comprising phosphorylation, acetylation and ubiquitylation regulate the activity of c-Myc. Recently, it was shown that c-Myc-driven tumors are strongly dependent on the SUMO pathway. Currently, the relevant SUMO target proteins in this pathway are unknown. Here we show that c-Myc is a target protein for SUMOylation, and that SUMOylated c-Myc is subsequently ubiquitylated and degraded by the proteasome. SUMO chains appeared to be dispensable for this process, polymerization-deficient SUMO mutants supported proteolysis of SUMOylated c-Myc. These results indicate that multiple SUMO monomers conjugated to c-Myc could be sufficient to direct SUMOylated c-Myc to the ubiquitin-proteasome pathway. Knocking down the SUMO-targeted ubiquitin ligase RNF4 enhanced the levels of SUMOylated c-Myc, indicating that RNF4 could recognize a multi-SUMOylated protein as a substrate in addition to poly-SUMOylated proteins. Knocking down the SUMO E3 ligase PIAS1 resulted in reduced c-Myc SUMOylation and increased c-Myc transcriptional activity, indicating that PIAS1 mediates c-Myc SUMOylation. Increased SUMOylation of c-Myc was noted upon knockdown of the SUMO protease SENP7, indicating that it also could regulate a multi-SUMOylated protein in addition to poly-SUMOylated proteins. C-Myc lacks KxE-type SUMOylation consensus motifs. We used mass spectrometry to identify 10 SUMO acceptor lysines: K52, K148, K157, K317, K323, K326, K389, K392, K398 and K430. Intriguingly, mutating all 10 SUMO acceptor lysines did not reduce c-Myc SUMOylation, suggesting that SUMO acceptor lysines in c-Myc act promiscuously. Our results provide novel insight into the complexity of c-Myc post-translational regulation. PMID:25895136

  20. A Mouse Strain Defective in Both T Cells and NK Cells Has Enhanced Sensitivity to Tumor Induction by Plasmid DNA Expressing Both Activated H-Ras and c-Myc

    PubMed Central

    Sheng-Fowler, Li; Tu, Wei; Fu, Haiqing; Murata, Haruhiko; Lanning, Lynda; Foseh, Gideon; Macauley, Juliete; Blair, Donald; Hughes, Stephen H.; Coffin, John M.; Lewis, Andrew M.; Peden, Keith

    2014-01-01

    As part of safety studies to evaluate the risk of residual cellular DNA in vaccines manufactured in tumorigenic cells, we have been developing in vivo assays to detect and quantify the oncogenic activity of DNA. We generated a plasmid expressing both an activated human H-ras gene and murine c-myc gene and showed that 1 µg of this plasmid, pMSV-T24-H-ras/MSV-c-myc, was capable of inducing tumors in newborn NIH Swiss mice. However, to be able to detect the oncogenicity of dominant activated oncogenes in cellular DNA, a more sensitive system was needed. In this paper, we demonstrate that the newborn CD3 epsilon transgenic mouse, which is defective in both T-cell and NK-cell functions, can detect the oncogenic activity of 25 ng of the circular form of pMSV-T24-H-ras/MSV-c-myc. When this plasmid was inoculated as linear DNA, amounts of DNA as low as 800 pg were capable of inducing tumors. Animals were found that had multiple tumors, and these tumors were independent and likely clonal. These results demonstrate that the newborn CD3 epsilon mouse is highly sensitive for the detection of oncogenic activity of DNA. To determine whether it can detect the oncogenic activity of cellular DNA derived from four human tumor-cell lines (HeLa, A549, HT-1080, and CEM), DNA (100 µg) was inoculated into newborn CD3 epsilon mice both in the presence of 1 µg of linear pMSV-T24-H-ras/MSV-c-myc as positive control and in its absence. While tumors were induced in 100% of mice with the positive-control plasmid, no tumors were induced in mice receiving any of the tumor DNAs alone. These results demonstrate that detection of oncogenes in cellular DNA derived from four human tumor-derived cell lines in this mouse system was not possible; the results also show the importance of including a positive-control plasmid to detect inhibitory effects of the cellular DNA. PMID:25302710

  1. The C-terminus of nucleolin promotes the formation of the c-MYC G-quadruplex and inhibits c-MYC promoter activity.

    PubMed

    González, Verónica; Hurley, Laurence H

    2010-11-16

    Nucleolin, the most abundant nucleolar phosphoprotein of eukaryotic cells, is known primarily for its role in ribosome biogenesis and cell proliferation. It is, however, a multifunctional protein that, depending on the cellular context, can drive either cell proliferation or apoptosis. Our laboratory recently demonstrated that nucleolin can function as a repressor of c-MYC transcription by binding to and stabilizing the formation of a G-quadruplex structure in a region of the c-MYC promoter responsible for controlling 85-90% of c-MYC's transcriptional activity. In this study, we investigate the structural elements of nucleolin that are required for c-MYC repression. The effect of nucleolin deletion mutants on the formation and stability of the c-MYC G-quadruplex, as well as c-MYC transcriptional activity, was assessed by circular dichroism spectropolarimetry, thermal stability, and in vitro transcription. Here we report that nucleolin's RNA binding domains 3 and 4, as well as the arginine-glycine-glycine (RGG) domain, are required to repress c-MYC transcription. PMID:20932061

  2. c-Myc dependent initiation of genomic instability during neoplastic transformation.

    PubMed

    Taylor, C; Jalava, A; Mai, S

    1997-01-01

    The dihydrofolate reductase (DHFR) gene is a target of c-Myc in genomic instability. The induced overexpression of c-Myc in cell lines is followed by the amplification and rearrangement of the DHFR gene. Furthermore, the constitutive upregulation of c-Myc protein coincides with genomic instability of the DHFR gene in lymphoid, non-lymphoid and in tumor lines. The amplification of the DHFR gene is locus-specific and independent of species origins. We have now addressed the question whether inducible deregulation of c-Myc is followed by DHFR gene amplification in vivo. We show that the DHFR gene is a target of c-Myc-dependent neoplasia in vivo and propose a role for genomic instability during the initiation of neoplastic transformation. PMID:9308243

  3. Regulation of OGT by URI in Response to Glucose Confers c-MYC-Dependent Survival Mechanisms.

    PubMed

    Burén, Stefan; Gomes, Ana L; Teijeiro, Ana; Fawal, Mohamad-Ali; Yilmaz, Mahmut; Tummala, Krishna S; Perez, Manuel; Rodriguez-Justo, Manuel; Campos-Olivas, Ramón; Megías, Diego; Djouder, Nabil

    2016-08-01

    Cancer cells can adapt and survive under low nutrient conditions, but underlying mechanisms remain poorly explored. We demonstrate here that glucose maintains a functional complex between the co-chaperone URI, PP1γ, and OGT, the enzyme catalyzing O-GlcNAcylation. Glucose deprivation induces the activation of PKA, which phosphorylates URI at Ser-371, resulting in PP1γ release and URI-mediated OGT inhibition. Low OGT activity reduces O-GlcNAcylation and promotes c-MYC degradation to maintain cell survival. In the presence of glucose, PP1γ-bound URI increases OGT and c-MYC levels. Accordingly, mice expressing non-phosphorylatable URI (S371A) in hepatocytes exhibit high OGT activity and c-MYC stabilization, accelerating liver tumorigenesis in agreement with c-MYC oncogenic functions. Our work uncovers that URI-regulated OGT confers c-MYC-dependent survival functions in response to glucose fluctuations. PMID:27505673

  4. Downregulation of c-Myc is involved in TLR3-mediated tumor death of neuroblastoma xenografts.

    PubMed

    Lin, Li-Ling; Huang, Chao-Cheng; Wu, Chia-Ling; Wu, Min-Tsui; Hsu, Wen-Ming; Chuang, Jiin-Haur

    2016-07-01

    Neuroblastoma (NB) is the deadliest pediatric solid tumor due to its pleomorphic molecular characteristics. In the innate immune system, toll-like receptor 3 (TLR3) recognizes viral double-stranded RNAs to initiate immune signaling. Positive TLR3 expression indicates a favorable prognosis in NB patients, and is associated with MYCN-non-amplified. However, TLR3-mediated innate immune responses remain elusive in NB. In this study, we attempted to dissect the molecular mechanism underlying TLR3-agonist polyinosinic-polycytidylic acid [poly(I:C)] treatment in NB in vivo. We established NB xenograft models in non-obese diabetic/severe combined immunodeficiency (NOD/SCID) mice with MYCN-amplified SK-N-DZ (DZ) cells or MYCN-non-amplified SK-N-AS (AS) cells. Poly(I:C) treatment led to significant tumor regression in AS xenografts, but not in DZ xenografts. Through immunohistochemical analysis, significant suppression of tumor proliferation, downregulation of c-Myc expression, and upregulation of TLR3 expression were found in the treatment group. Poly(I:C) inducing activation of TLR3/IRF3-mediated innate immunity associated with downregulation of c-Myc can be found in MYCN-non-amplified SK-N-AS cells, but not in MYCN-amplified BE(2)-M17 cells. Knockdown of TLR3 disturbed poly(I:C)-induced suppression of c-Myc and upregulation of p-IRF3 in AS cells. Furthermore, poly(I:C) treatment upregulated active NF-κB, mitochondrial antioxidant manganese superoxide dismutase and 8-hydroxydeoxyguanosine, which works with reactive oxygen species (ROS) generation and DNA damage. Upregulation of active caspase 3 and cleaved poly [ADP-ribose] polymerase 1 were found in poly(I:C)-treated AS xenografts, which indicates the induction of apoptosis. Thus, our results suggest that c-Myc overexpression may increase sensitivity to poly(I:C)-induced tumor growth arrest and ROS-mediated apoptosis in NB. This study demonstrates that c-Myc protein expression has an important role in TLR3-induced innate

  5. Sequential and Coordinated Actions of c-Myc and N-Myc Control Appendicular Skeletal Development

    PubMed Central

    Ota, Sara; Akiyama, Haruhiko; Keene, Douglas R.; Hurlin, Peter J.

    2011-01-01

    Background During limb development, chondrocytes and osteoblasts emerge from condensations of limb bud mesenchyme. These cells then proliferate and differentiate in separate but adjacent compartments and function cooperatively to promote bone growth through the process of endochondral ossification. While many aspects of limb skeletal formation are understood, little is known about the mechanisms that link the development of undifferentiated limb bud mesenchyme with formation of the precartilaginous condensation and subsequent proliferative expansion of chondrocyte and osteoblast lineages. The aim of this study was to gain insight into these processes by examining the roles of c-Myc and N-Myc in morphogenesis of the limb skeleton. Methodology/Principal Findings To investigate c-Myc function in skeletal development, we characterized mice in which floxed c-Myc alleles were deleted in undifferentiated limb bud mesenchyme with Prx1-Cre, in chondro-osteoprogenitors with Sox9-Cre and in osteoblasts with Osx1-Cre. We show that c-Myc promotes the proliferative expansion of both chondrocytes and osteoblasts and as a consequence controls the process of endochondral growth and ossification and determines bone size. The control of proliferation by c-Myc was related to its effects on global gene transcription, as phosphorylation of the C-Terminal Domain (pCTD) of RNA Polymerase II, a marker of general transcription initiation, was tightly coupled to cell proliferation of growth plate chondrocytes where c-Myc is expressed and severely downregulated in the absence of c-Myc. Finally, we show that combined deletion of N-Myc and c-Myc in early limb bud mesenchyme gives rise to a severely hypoplastic limb skeleton that exhibits features characteristic of individual c-Myc and N-Myc mutants. Conclusions/Significance Our results show that N-Myc and c-Myc act sequentially during limb development to coordinate the expansion of key progenitor populations responsible for forming the limb

  6. Hepatocyte growth factor-stimulated renal tubular mitogenesis: effects on expression of c-myc, c-fos, c-met, VEGF and the VHL tumour-suppressor and related genes.

    PubMed Central

    Clifford, S. C.; Czapla, K.; Richards, F. M.; O'Donoghue, D. J.; Maher, E. R.

    1998-01-01

    Hepatocyte growth factor (HGF/SF) is a potent renal proximal tubular cell (PTEC) mitogen involved in renal development. HGF/SF is the functional ligand for the c-met proto-oncogene, and germline c-met mutations are associated with familial papillary renal cell carcinoma. Somatic von Hippel-Lindau disease tumour-suppressor gene (VHL) mutations are frequently detected in sporadic clear cell renal cell carcinomas (RCC), and germline VHL mutations are the commonest cause of familial clear cell RCC. pVHL binds to the positive regulatory components of the trimeric elongin (SIII) complex (elongins B and C) and has been observed to deregulate expression of the vascular endothelial growth factor (VEGF) gene. HGF/SF has similarly been reported to up-regulate expression of the VEGF gene in non-renal experimental systems. To investigate the mechanism of HGF/SF action in PTECs and, specifically, to examine potential interactions between the HGF/c-met and the VHL-mediated pathways for renal tubular growth control, we have isolated untransformed PTECs from normal kidneys, developed conditions for their culture in vitro and used these cells to investigate changes in mRNA levels of the VHL, elongin A, B and C, VEGF, c-myc, c-fos and c-met genes after HGF/SF exposure. Significant elevations in the mRNA levels of VEGF, c-myc, c-fos, c-met and elongins A, B and C, but not VHL, were detected after HGF/SF stimulation of human PTECs (P < 0.02), with a consistent order of peak levels observed over successive replicates (c-fos at 1 h, VEGF at 2-4 h, c-myc, at 4 h, followed by c-met and all three elongin subunits at 8 h). This study highlights the spectrum of changes in gene expression observed in PTECs after HGF/SF stimulation and has identified possible candidate mediators of the HGF/SF-induced mitogenic response. Our evidence would suggest that the changes in PTEC VEGF expression induced by HGF/SF are mediated by a VHL-independent pathway. Images Figure 1 PMID:9652757

  7. Androgen Receptor (AR) Suppresses Normal Human Prostate Epithelial Cell Proliferation via AR/β-catenin/TCF-4 Complex Inhibition of c-MYC Transcription

    PubMed Central

    Antony, Lizamma; van der Schoor, Freek; Dalrymple, Susan L.; Isaacs, John T.

    2016-01-01

    INTRODUCTION Physiologic testosterone continuously stimulates prostate stromal cell secretion of paracrine growth factors (PGFs), which if unopposed would induce hyperplastic overgrowth of normal prostate epithelial cells (PrECs). METHODS Lentiviral shRNA stable knock down of c-MYC, β-catenin, or TCF-4 completely inhibits normal (i.e., non-transformed) human PrECs growth. c-MYC enhancer driven reporter expression and growth is inhibited by two chemically distinct molecules, which prevent β-catenin signaling either by blocking TCF-4 binding (i.e., toxoflavin) or by stimulating degradation (i.e., AVX939). Recombinant DKK1 protein at a dose, which inhibits activation of canonical Wnt signaling does not inhibit PrEC growth. Nuclear β-catenin translocation and PrEC growth is prevented by both lack of PGFs or Akt inhibitor-I. Growth inhibition induced by lack of PGFs, toxoflavin, or Akt inhibitor-I is overcome by constitutive c-MYC transcription. RESULTS In the presence of continuous PGF signaling, PrEC hyperplasia is prevented by androgen binding to AR suppressing c-MYC transcription, resulting in G0 arrest/terminal differentiation independent of Rb, p21, p27, FoxP3, or down regulation of growth factors receptors and instead involves androgen-induced formation of AR/β-catenin/TCF-4 complexes, which suppress c-MYC transcription. Such suppression does not occur when AR is mutated in its zinc-finger binding domain. DISCUSSION Proliferation of non-transformed human PrECs is dependent upon c-MYC transcription via formation/binding of β-catenin/TCF-4 complexes at both 5′ and 3′ c-MYC enhancers stimulated by Wnt-independent, PGF induced Akt signaling. In the presence of continuous PGF signaling, PrEC hyperplasia is prevented by androgen-induced formation of AR/β-catenin/TCF-4 complexes, which retains binding to 3′ c-MYC enhancer, but now suppresses c-MYC transcription. PMID:24913829

  8. c-Myc regulates cell size and ploidy but is not essential for postnatal proliferation in liver

    NASA Astrophysics Data System (ADS)

    Baena, Esther; Gandarillas, Alberto; Vallespinós, Mireia; Zanet, Jennifer; Bachs, Oriol; Redondo, Clara; Fabregat, Isabel; Martinez-A., Carlos; Moreno de Alborán, Ignacio

    2005-05-01

    The c-Myc protein is a transcription factor implicated in the regulation of multiple biological processes, including cell proliferation, cell growth, and apoptosis. In vivo overexpression of c-myc is linked to tumor development in a number of mouse models. Here, we show that perinatal inactivation of c-Myc in liver causes disorganized organ architecture, decreased hepatocyte size, and cell ploidy. Furthermore, c-Myc appears to have distinct roles in proliferation in liver. Thus, postnatal hepatocyte proliferation does not require c-Myc, whereas it is necessary for liver regeneration in adult mice. These results show novel physiological functions of c-myc in liver development and hepatocyte proliferation and growth.

  9. Differential effects of c-myc and ABCB1 silencing on reversing drug resistance in HepG2/Dox cells.

    PubMed

    Yahya, Shaymaa M M; Hamed, Ahmed R; Emara, Mohamed; Soltan, Maha M; Abd-Ellatef, Gamal Eldein F; Abdelnasser, Salma M

    2016-05-01

    Multidrug resistance (MDR) in various kinds of cancers represents a true obstacle which hinders the successes of most of current available chemotherapies. ATP-binding cassette (ABC) trasporter proteins have been shown to contribute to the majority of MDR in various types of malignancies. c-myc has recently been reported to participate, at least partly, in MDR to some types of cancers. This study aimed to test whether c-myc could play a role, solely or with coordination with other ABCs, in the resistance of HepG2 cells to doxorubicin (Dox). MDR has been induced in wild-type HepG2 and has been verified both on gene and protein levels. Various assays including efflux assays as well as siRNA targeting ABCB1 and c-myc have been employed to explore the role of both candidate molecules in MDR in HepG2. Results obtained, with regard to ABCB1 silencing on HepG2/Dox cells, have shown that ABCB1-deficient cells exhibited a significant reduction in ABCC1 expression as compared to ABCB1-sufficient cells. However, these cells did not show a significant reduction in other tested ABCs (ABCC5 and ABCC10) while c-myc silencing had no significant effect on any of the studied ABCs. Moreover, silencing of ABCB1 on HepG2 significantly increased fluorescent calcein retention in HepG2 cells as compared to the control cells while downregulation of c-myc did not have any effect on fluorescent calcein retention. Altogether, this work clearly demonstrates that c-myc has no role in MDR of HepG2 to Dox which has been shown to be ABCB1-mediated in a mechanism which might involve ABCC1. PMID:26596829

  10. Multiple single-stranded cis elements are associated with activated chromatin of the human c-myc gene in vivo.

    PubMed Central

    Michelotti, G A; Michelotti, E F; Pullner, A; Duncan, R C; Eick, D; Levens, D

    1996-01-01

    Transcription activation and repression of eukaryotic genes are associated with conformational and topological changes of the DNA and chromatin, altering the spectrum of proteins associated with an active gene. Segments of the human c-myc gene possessing non-B structure in vivo located with enzymatic and chemical probes. Sites hypertensive to cleavage with single-strand-specific S1 nuclease or the single-strand-selective agent potassium permanganate included the major promoters P1 and P2 as well as the far upstream sequence element (FUSE) and CT elements, which bind, respectively, the single-strand-specific factors FUSE-binding protein and heterogeneous nuclear ribonucleoprotein K in vitro. Active and inactive c-myc genes yielded different patterns of S1 nuclease and permanganate sensitivity, indicating alternative chromatin configurations of active and silent genes. The melting of specific cis elements of active c-myc genes in vivo suggested that transcriptionally associated torsional strain might assist strand separation and facilitate factor binding. Therefore, the interaction of FUSE-binding protein and heterogeneous nuclear ribonucleoprotein K with supercoiled DNA was studied. Remarkably, both proteins recognize their respective elements torsionally strained but not as liner duplexes. Single-strand- or supercoil-dependent gene regulatory proteins may directly link alterations in DNA conformation and topology with changes in gene expression. PMID:8649373

  11. Endogenous c-Myc is essential for p53-induced apoptosis in response to DNA damage in vivo

    PubMed Central

    Phesse, T J; Myant, K B; Cole, A M; Ridgway, R A; Pearson, H; Muncan, V; van den Brink, G R; Vousden, K H; Sears, R; Vassilev, L T; Clarke, A R; Sansom, O J

    2014-01-01

    Recent studies have suggested that C-MYC may be an excellent therapeutic cancer target and a number of new agents targeting C-MYC are in preclinical development. Given most therapeutic regimes would combine C-MYC inhibition with genotoxic damage, it is important to assess the importance of C-MYC function for DNA damage signalling in vivo. In this study, we have conditionally deleted the c-Myc gene in the adult murine intestine and investigated the apoptotic response of intestinal enterocytes to DNA damage. Remarkably, c-Myc deletion completely abrogated the immediate wave of apoptosis following both ionizing irradiation and cisplatin treatment, recapitulating the phenotype of p53 deficiency in the intestine. Consistent with this, c-Myc-deficient intestinal enterocytes did not upregulate p53. Mechanistically, this was linked to an upregulation of the E3 Ubiquitin ligase Mdm2, which targets p53 for degradation in c-Myc-deficient intestinal enterocytes. Further, low level overexpression of c-Myc, which does not impact on basal levels of apoptosis, elicited sustained apoptosis in response to DNA damage, suggesting c-Myc activity acts as a crucial cell survival rheostat following DNA damage. We also identify the importance of MYC during DNA damage-induced apoptosis in several other tissues, including the thymus and spleen, using systemic deletion of c-Myc throughout the adult mouse. Together, we have elucidated for the first time in vivo an essential role for endogenous c-Myc in signalling DNA damage-induced apoptosis through the control of the p53 tumour suppressor protein. PMID:24583641

  12. Endogenous c-Myc is essential for p53-induced apoptosis in response to DNA damage in vivo.

    PubMed

    Phesse, T J; Myant, K B; Cole, A M; Ridgway, R A; Pearson, H; Muncan, V; van den Brink, G R; Vousden, K H; Sears, R; Vassilev, L T; Clarke, A R; Sansom, O J

    2014-06-01

    Recent studies have suggested that C-MYC may be an excellent therapeutic cancer target and a number of new agents targeting C-MYC are in preclinical development. Given most therapeutic regimes would combine C-MYC inhibition with genotoxic damage, it is important to assess the importance of C-MYC function for DNA damage signalling in vivo. In this study, we have conditionally deleted the c-Myc gene in the adult murine intestine and investigated the apoptotic response of intestinal enterocytes to DNA damage. Remarkably, c-Myc deletion completely abrogated the immediate wave of apoptosis following both ionizing irradiation and cisplatin treatment, recapitulating the phenotype of p53 deficiency in the intestine. Consistent with this, c-Myc-deficient intestinal enterocytes did not upregulate p53. Mechanistically, this was linked to an upregulation of the E3 Ubiquitin ligase Mdm2, which targets p53 for degradation in c-Myc-deficient intestinal enterocytes. Further, low level overexpression of c-Myc, which does not impact on basal levels of apoptosis, elicited sustained apoptosis in response to DNA damage, suggesting c-Myc activity acts as a crucial cell survival rheostat following DNA damage. We also identify the importance of MYC during DNA damage-induced apoptosis in several other tissues, including the thymus and spleen, using systemic deletion of c-Myc throughout the adult mouse. Together, we have elucidated for the first time in vivo an essential role for endogenous c-Myc in signalling DNA damage-induced apoptosis through the control of the p53 tumour suppressor protein. PMID:24583641

  13. Positive regulation of c-Myc by cohesin is direct, and evolutionarily conserved

    PubMed Central

    Rhodes, Jenny M.; Bentley, Fiona K.; Print, Cristin G.; Dorsett, Dale; Misulovin, Ziva; Dickinson, Emma J.; Crosier, Kathryn E.; Crosier, Philip S.; Horsfield, Julia A.

    2010-01-01

    Contact between sister chromatids from S phase to anaphase depends on cohesin, a large multi-subunit protein complex. Mutations in sister chromatid cohesion proteins underlie the human developmental condition, Cornelia de Lange Syndrome. Roles for cohesin in regulating gene expression, sometimes in combination with CCCTC-binding factor (CTCF), have emerged. We analyzed zebrafish embryos null for cohesin subunit rad21 using microarrays to determine global effects of cohesin on gene expression during embryogenesis. This identified Rad21-associated gene networks that included myca (zebrafish c-myc), p53 and mdm2. In zebrafish, cohesin binds to the transcription start sites of p53 and mdm2, and depletion of either Rad21 or CTCF increased their transcription. In contrast, myca expression was strongly downregulated upon loss of Rad21 while depletion of CTCF had little effect. Depletion of Rad21 or the cohesin-loading factor Nipped-B in Drosophila cells also reduced expression of myc and Myc target genes. Cohesin bound the transcription start site plus an upstream predicted CTCF binding site at zebrafish myca. Binding and positive regulation of the c-Myc gene by cohesin is conserved through evolution, indicating this regulation is likely to be direct. The exact mechanism of regulation is unknown, but local changes in histone modification associated with transcription repression at the myca gene were observed in rad21 mutants. PMID:20553708

  14. MicroRNA-449a enhances radiosensitivity by downregulation of c-Myc in prostate cancer cells

    PubMed Central

    Mao, Aihong; Zhao, Qiuyue; Zhou, Xin; Sun, Chao; Si, Jing; Zhou, Rong; Gan, Lu; Zhang, Hong

    2016-01-01

    MicroRNAs (miRNAs) have been reported to be involved in DNA damage response induced by ionizing radiation (IR). c-Myc is reduced when cells treated with IR or other DNA damaging agents. It is unknown whether miRNAs participate in c-Myc downregulation in response to IR. In the present study, we found that miR-449a enhanced radiosensitivity in vitro and in vivo by targeting c-Myc in prostate cancer (LNCaP) cells. MiR-449a was upregulated and c-Myc was downregulated in response to IR in LNCaP cells. Overexpression of miR-449a or knockdown of c-Myc promoted the sensitivity of LNCaP cells to IR. By establishing c-Myc as a direct target of miR-449a, we revealed that miR-449a enhanced radiosensitivity by repressing c-Myc expression in LNCaP cells. Furthermore, we showed that miR-449a enhanced radiation-induced G2/M phase arrest by directly downregulating c-Myc, which controlled the Cdc2/CyclinB1 cell cycle signal by modulating Cdc25A. These results highlight an unrecognized mechanism of miR-449a-mediated c-Myc regulation in response to IR and may provide alternative therapeutic strategies for the treatment of prostate cancer. PMID:27250340

  15. MicroRNA-449a enhances radiosensitivity by downregulation of c-Myc in prostate cancer cells.

    PubMed

    Mao, Aihong; Zhao, Qiuyue; Zhou, Xin; Sun, Chao; Si, Jing; Zhou, Rong; Gan, Lu; Zhang, Hong

    2016-01-01

    MicroRNAs (miRNAs) have been reported to be involved in DNA damage response induced by ionizing radiation (IR). c-Myc is reduced when cells treated with IR or other DNA damaging agents. It is unknown whether miRNAs participate in c-Myc downregulation in response to IR. In the present study, we found that miR-449a enhanced radiosensitivity in vitro and in vivo by targeting c-Myc in prostate cancer (LNCaP) cells. MiR-449a was upregulated and c-Myc was downregulated in response to IR in LNCaP cells. Overexpression of miR-449a or knockdown of c-Myc promoted the sensitivity of LNCaP cells to IR. By establishing c-Myc as a direct target of miR-449a, we revealed that miR-449a enhanced radiosensitivity by repressing c-Myc expression in LNCaP cells. Furthermore, we showed that miR-449a enhanced radiation-induced G2/M phase arrest by directly downregulating c-Myc, which controlled the Cdc2/CyclinB1 cell cycle signal by modulating Cdc25A. These results highlight an unrecognized mechanism of miR-449a-mediated c-Myc regulation in response to IR and may provide alternative therapeutic strategies for the treatment of prostate cancer. PMID:27250340

  16. Bag-1 promotes cell survival through c-Myc-mediated ODC upregulation that is not preferred under apoptotic stimuli in MCF-7 cells.

    PubMed

    Ozfiliz, Pelin; Kizilboga, Tugba; Demir, Salih; Alkurt, Gizem; Palavan-Unsal, Narçin; Arisan, Elif Damla; Dinler-Doganay, Gizem

    2015-07-01

    Bag-1, Bcl-2 associated athanogene-1, is a multifunctional protein that can regulate a wide variety of cellular processes: proliferation, cell survival, transcription, apoptosis and motility. Bag-1 interacts with various targets in the modulation of these pathways; yet molecular details of Bag-1's involvement in each cellular event are still unclear. We first showed that forced Bag-1 expression promotes cell survival and prevents drug-induced apoptosis in MCF-7 breast cancer cells. Increased mRNA expressions of c-myc protooncogene and ornithine decarboxylase (ODC), biosynthetic enzyme of polyamines, were detected in Bag-1L+ cells, and western blots against the protein product of c-Myc and ODC confirmed these findings. Once ODC, a c-Myc target, gets activated, polyamine biosynthesis increases. We observed enhanced polyamine content in the Bag-1L+ cells. On the contrary, when polyamine catabolic mechanisms were investigated, Bag-1 silencing suppressed biosynthesis of polyamines because of the downregulation of ODC and upregulation of PAO. Exposure of cells to apoptotic inducers enhances the cell death mechanism by producing toxic products such as H2 O2 and aldehydes. Bag-1L+ cells prevented drug-induced PAO activation leading to a decrease in H2 O2 production following cisplatin or paclitaxel treatment. In this line, our results suggested that Bag-1 indirectly affects cell survival through c-Myc activated signalling that causes elevation of ODC levels, leading to an increase of the polyamine content. PMID:26178413

  17. The c-MYC-ABCB5 axis plays a pivotal role in 5-fluorouracil resistance in human colon cancer cells.

    PubMed

    Kugimiya, Naruji; Nishimoto, Arata; Hosoyama, Tohru; Ueno, Koji; Enoki, Tadahiko; Li, Tao-Sheng; Hamano, Kimikazu

    2015-07-01

    c-MYC overexpression is frequently observed in various cancers including colon cancer and regulates many biological activities such as aberrant cell proliferation, apoptosis, genomic instability, immortalization and drug resistance. However, the mechanism by which c-MYC confers drug resistance remains to be fully elucidated. In this study, we found that the c-MYC expression level in primary colorectal cancer tissues correlated with the recurrence rate following 5-fluorouracil (5-FU)-based adjuvant chemotherapy. Supporting this finding, overexpression of exogenous c-MYC increased the survival rate following 5-FU treatment in human colon cancer cells, and knockdown of endogenous c-MYC decreased it. Furthermore, c-MYC knockdown decreased the expression level of ABCB5, which is involved in 5-FU resistance. Using a chromatin immunoprecipitation assay, we found that c-MYC bound to the ABCB5 promoter region. c-MYC inhibitor (10058-F4) treatment inhibited c-MYC binding to the ABCB5 promoter, leading to a decrease in ABCB5 expression level. ABCB5 knockdown decreased the survival rate following 5-FU treatment as expected, and the ABCB5 expression level was increased in 5-FU-resistant human colon cancer cells. Finally, using a human colon cancer xenograft murine model, we found that the combined 5-FU and 10058-F4 treatment significantly decreased tumorigenicity in nude mice compared with 5-FU or 10058-F4 treatment alone. 10058-F4 treatment decreased the ABCB5 expression level in the presence or absence of 5-FU. In contrast, 5-FU treatment alone increased the ABCB5 expression level. Taken together, these results suggest that c-MYC confers resistance to 5-FU through regulating ABCB5 expression in human colon cancer cells. PMID:25689483

  18. Transcriptional regulation of Wnt inhibitory factor-1 by Miz-1/c-Myc

    PubMed Central

    Licchesi, JDF; Van Neste, L; Tiwari, VK; Cope, L; Lin, X; Baylin, SB; Herman, JG

    2011-01-01

    The Wnt signaling pathway is capable of self-regulation through positive and negative feedback mechanisms. For example, the oncoprotein c-Myc, which is upregulated by Wnt signaling activity, participates in a positive feedback loop of canonical Wnt signaling through repression of Wnt antagonists DKK1 and SFRP1. In this study, we investigated the mechanism of Wnt inhibitory factor-1 (WIF-1) silencing. Mapping of CpG island methylation of the WIF-1 promoter reveals regional methylation (–295 to –95 bp from the transcription start site) that correlates with transcriptional silencing. We identified Miz-1 as a direct activator of WIF-1 transcriptional activity, which is found at WIF-1 promoter. In addition, we show that c-Myc contributes to WIF-1 transcriptional repression in a Miz-1-dependent manner. Although the transient repression mediated by Miz-1/c-Myc is independent of de novo methylation, the stable repression by this complex is associated with CpG island methylation of the critical –295 to –95-bp region of the WIF-1 promoter. Importantly, Miz-1 and c-Myc are found at WIF-1 promoter in WIF-1 non-expressing cell lines DLD-1 and 209myc. Transient knockdown or somatic knockout of c-Myc in DLD-1 failed to restore WIF-1 expression suggesting that c-Myc is involved in initiating rather than maintaining WIF-1 epigenetic silencing. In a genome-wide screen, DNAJA4, TGFβ-induced and TRIM59 were repressed by c-Myc overexpression and DNA promoter hypermethylation. Our data reveal novel insights into c-Myc-mediated DNA methylation-dependent transcriptional silencing, a mechanism that might contribute to the dysregulation of Wnt signaling in cancer. PMID:20697356

  19. Cyclin D1 Is Transcriptionally Down-Regulated by ZO-2 via an E Box and the Transcription Factor c-Myc

    PubMed Central

    Huerta, Miriam; Muñoz, Rodrigo; Tapia, Rocío; Soto-Reyes, Ernesto; Ramírez, Leticia; Recillas-Targa, Félix; González-Mariscal, Lorenza

    2007-01-01

    Recent reports have indicated the participation of tight junction (TJ) proteins in the regulation of gene expression and cell proliferation. Here, we have studied the role of zona occludens (ZO)-2, a TJ peripheral protein, in the regulation of cyclin D1 transcription. We found that ZO-2 down-regulates cyclin D1 transcription in a dose-dependent manner. To understand how ZO-2 represses cyclin D1 promoter activity, we used deletion analyses and found that ZO-2 negatively regulates cyclin D1 transcription via an E box and that it diminishes cell proliferation. Because ZO-2 does not associate directly with DNA, electrophoretic mobility shift assay and chromatin immunoprecipitation (ChIP) assay were used to identify the transcription factors mediating the ZO-2–repressive effect. c-Myc was found to bind the E box present in the cyclin D1 promoter, and the overexpression of c-Myc augmented the inhibition generated by ZO-2 transfection. The presence of ZO-2 and c-Myc in the same complex was further demonstrated by immunoprecipitation. ChIP and reporter gene assays using histone deacetylases (HDACs) inhibitors demonstrated that HDACs are necessary for ZO-2 repression and that HDAC1 is recruited to the E box. We conclude that ZO-2 down-regulates cyclin D1 transcription by interacting with the c-Myc/E box element and by recruiting HDAC1. PMID:17881732

  20. Distinct nuclear arrangement of active and inactive c-myc genes in control and differentiated colon carcinoma cells

    SciTech Connect

    Harnicarova, Andrea; Kozubek, Stanislav . E-mail: kozubek@ibp.cz; Pachernik, Jiri; Krejci, Jana; Bartova, Eva

    2006-12-10

    Using sequential RNA-DNA fluorescence in situ hybridization, the nuclear arrangement of both the active and inactive c-myc gene as well as its transcription was investigated in colon cancer HT-29 cells induced to differentiate into enterocytes. Cytogenetic studies revealed the presence of two chromosomes 8 in HT-29 cells, of which the one containing c-myc gene amplicons was substantially larger and easily distinguished from the normal chromosome. This observation enabled detection of both activity and nuclear localization of c-myc genes in single cells and in individual chromosome territories. Similar transcriptional activity of the c-myc gene was observed in both the normal and derivative chromosome 8 territories showing no influence of the amplification on the c-myc gene expression. Our experiments demonstrate strikingly specific nuclear and territorial arrangements of active genes as compared with inactive ones: on the periphery of their territories facing to the very central region of the cell nucleus. Nuclear arrangement of c-myc genes and transcripts was conserved during cell differentiation and, therefore, independent of the level of differentiation-specific c-myc gene expression. However, after the induction of differentiation, a more internal territorial location was found for the single copy c-myc gene of normal chromosome 8, while amplicons conserved their territorial topography.

  1. ELL targets c-Myc for proteasomal degradation and suppresses tumour growth

    PubMed Central

    Chen, Yu; Zhou, Chi; Ji, Wei; Mei, Zhichao; Hu, Bo; Zhang, Wei; Zhang, Dawei; Wang, Jing; Liu, Xing; Ouyang, Gang; Zhou, Jiangang; Xiao, Wuhan

    2016-01-01

    Increasing evidence supports that ELL (eleven–nineteen lysine-rich leukaemia) is a key regulator of transcriptional elongation, but the physiological function of Ell in mammals remains elusive. Here we show that ELL functions as an E3 ubiquitin ligase and targets c-Myc for proteasomal degradation. In addition, we identify that UbcH8 serves as a ubiquitin-conjugating enzyme in this pathway. Cysteine 595 of ELL is an active site of the enzyme; its mutation to alanine (C595A) renders the protein unable to promote the ubiquitination and degradation of c-Myc. ELL-mediated c-Myc degradation inhibits c-Myc-dependent transcriptional activity and cell proliferation, and also suppresses c-Myc-dependent xenograft tumour growth. In contrast, the ELL(C595A) mutant not only loses the ability to inhibit cell proliferation and xenograft tumour growth, but also promotes tumour metastasis. Thus, our work reveals a previously unrecognized function for ELL as an E3 ubiquitin ligase for c-Myc and a potential tumour suppressor. PMID:27009366

  2. Induction of c-fos and c-myc mRNA by epidermal growth factor or calcium ionophore is cAMP dependent.

    PubMed Central

    Ran, W; Dean, M; Levine, R A; Henkle, C; Campisi, J

    1986-01-01

    Phorbol esters activate protein kinase C and induce expression of the c-fos and c-myc protooncogenes in density-arrested BALB/c 3T3 (A31) cells; in contrast, epidermal growth factor (EGF) does not activate protein kinase C and is a poor inducer of c-fos and c-myc in these confluent cells. We show that, when A31 cells were subconfluent and made quiescent by serum deprivation, the phorbol ester phorbol 12-myristate 13-acetate induced c-fos and c-myc mRNA poorly, whereas EGF was a better inducer. Another platelet-derived growth factor-inducible gene, JE, did not show this differential regulation by phorbol 12-myristate 13-acetate and EGF. The ability of EGF to induce protooncogene mRNA was associated with elevated levels of intracellular cAMP. First, serum-deprived cells maintained cAMP at about 2-fold higher level than density-arrested cells. Second, induction was greatly enhanced by cholera toxin and 3-isobutyl-1-methylxanthine, which increased intracellular cAMP 3- to 10-fold. The calcium ionophore A23187 mimicked EGF in that it elevated c-fos and c-myc mRNA when administered with cholera toxin and isobutylmethylxanthine. Neither cholera toxin and isobutyl-methylxanthine nor A23187 appreciably induced these mRNAs when used alone. Our results suggest that c-fos and c-myc expression can be regulated by an EGF-directed pathway that utilizes calcium and cAMP as cooperating cytoplasmic messengers. Images PMID:2430281

  3. Dual targeting of p53 and c-MYC selectively eliminates leukaemic stem cells.

    PubMed

    Abraham, Sheela A; Hopcroft, Lisa E M; Carrick, Emma; Drotar, Mark E; Dunn, Karen; Williamson, Andrew J K; Korfi, Koorosh; Baquero, Pablo; Park, Laura E; Scott, Mary T; Pellicano, Francesca; Pierce, Andrew; Copland, Mhairi; Nourse, Craig; Grimmond, Sean M; Vetrie, David; Whetton, Anthony D; Holyoake, Tessa L

    2016-06-16

    Chronic myeloid leukaemia (CML) arises after transformation of a haemopoietic stem cell (HSC) by the protein-tyrosine kinase BCR-ABL. Direct inhibition of BCR-ABL kinase has revolutionized disease management, but fails to eradicate leukaemic stem cells (LSCs), which maintain CML. LSCs are independent of BCR-ABL for survival, providing a rationale for identifying and targeting kinase-independent pathways. Here we show--using proteomics, transcriptomics and network analyses--that in human LSCs, aberrantly expressed proteins, in both imatinib-responder and non-responder patients, are modulated in concert with p53 (also known as TP53) and c-MYC regulation. Perturbation of both p53 and c-MYC, and not BCR-ABL itself, leads to synergistic cell kill, differentiation, and near elimination of transplantable human LSCs in mice, while sparing normal HSCs. This unbiased systems approach targeting connected nodes exemplifies a novel precision medicine strategy providing evidence that LSCs can be eradicated. PMID:27281222

  4. The opposing transcriptional functions of Sin3a and c-Myc are required to maintain tissue homeostasis.

    PubMed

    Nascimento, Elisabete M; Cox, Claire L; MacArthur, Stewart; Hussain, Shobbir; Trotter, Matthew; Blanco, Sandra; Suraj, Menon; Nichols, Jennifer; Kübler, Bernd; Benitah, Salvador Aznar; Hendrich, Brian; Odom, Duncan T; Frye, Michaela

    2011-12-01

    How the proto-oncogene c-Myc balances the processes of stem-cell self-renewal, proliferation and differentiation in adult tissues is largely unknown. We explored c-Myc's transcriptional roles at the epidermal differentiation complex, a locus essential for skin maturation. Binding of c-Myc can simultaneously recruit (Klf4, Ovol-1) and displace (Cebpa, Mxi1 and Sin3a) specific sets of differentiation-specific transcriptional regulators to epidermal differentiation complex genes. We found that Sin3a causes deacetylation of c-Myc protein to directly repress c-Myc activity. In the absence of Sin3a, genomic recruitment of c-Myc to the epidermal differentiation complex is enhanced, and re-activation of c-Myc-target genes drives aberrant epidermal proliferation and differentiation. Simultaneous deletion of c-Myc and Sin3a reverts the skin phenotype to normal. Our results identify how the balance of two transcriptional key regulators can maintain tissue homeostasis through a negative feedback loop. PMID:22101514

  5. Design of a novel triple helix-forming oligodeoxyribonucleotide directed to the major promoter of the c-myc gene

    PubMed Central

    McGuffie, E. M.; Catapano, C. V.

    2002-01-01

    Altered expression of c-myc is implicated in pathogenesis and progression of many human cancers. Triple helix-forming oligonucleotides (TFOs) directed to a polypurine/polypyrimidine sequence in a critical regulatory region near the c-myc P2 promoter have been shown to inhibit c-myc transcription in vitro and in cells. However, these guanine-rich TFOs had moderate binding affinity and required high concentrations for activity. The 23 bp myc P2 sequence is split equally into AT- and GC-rich tracts. Gel mobility analysis of a series of short TFOs directed in parallel and anti-parallel orientation to the purine strand of each tract showed that only parallel CT and anti-parallel GT TFOs formed stable triplex on the AT- and GC-rich tracts, respectively. A novel full-length GTC TFO was designed to bind simultaneously in parallel and anti-parallel orientation to the polypurine strand. Gel-shift and footprinting assays showed that the new TFO formed a triple helix in physiological conditions with significantly higher affinity than an anti-parallel TFO. Protein-binding assays showed that 1 µM GTC TFO inhibited binding of nuclear transcription factors to the P2 promoter sequence. The novel TFO can be developed into a potent antigene agent, and its design strategy applied to similar genomic sequences, thus expanding the TFO repertoire. PMID:12060688

  6. SREBP-2 promotes stem cell-like properties and metastasis by transcriptional activation of c-Myc in prostate cancer

    PubMed Central

    Li, Xiangyan; Wu, Jason Boyang; Li, Qinlong; Shigemura, Katsumi; Chung, Leland W.K.; Huang, Wen-Chin

    2016-01-01

    Sterol regulatory element-binding protein-2 (SREBP-2) transcription factor mainly controls cholesterol biosynthesis and homeostasis in normal cells. The role of SREBP-2 in lethal prostate cancer (PCa) progression remains to be elucidated. Here, we showed that expression of SREBP-2 was elevated in advanced pathologic grade and metastatic PCa and significantly associated with poor clinical outcomes. Biofunctional analyses demonstrated that SREBP-2 induced PCa cell proliferation, invasion and migration. Furthermore, overexpression of SREBP-2 increased the PCa stem cell population, prostasphere-forming ability and tumor-initiating capability, whereas genetic silencing of SREBP-2 inhibited PCa cell growth, stemness, and xenograft tumor growth and metastasis. Clinical and mechanistic data showed that SREBP-2 was positively correlated with c-Myc and induced c-Myc activation by directly interacting with an SREBP-2-binding element in the 5′-flanking c-Myc promoter region to drive stemness and metastasis. Collectively, these clinical and experimental results reveal a novel role of SREBP-2 in the induction of a stem cell-like phenotype and PCa metastasis, which sheds light on translational potential by targeting SREBP-2 as a promising therapeutic approach in PCa. PMID:26883200

  7. c-MYC Copy-Number Gain Is an Independent Prognostic Factor in Patients with Colorectal Cancer

    PubMed Central

    Lee, Kyu Sang; Kwak, Yoonjin; Nam, Kyung Han; Kim, Duck-Woo; Kang, Sung-Bum; Choe, Gheeyoung; Kim, Woo Ho; Lee, Hye Seung

    2015-01-01

    Background The aim of this study was to determine the incidence and clinicopathological significance of c-MYC gene copy-number (GCN) gain in patients with primary colorectal cancer (CRC). Methods The c-MYC GCN was investigated in 367 consecutive CRC patients (cohort 1) by using dual-color silver in situ hybridization. Additionally, to evaluate regional heterogeneity, we examined CRC tissue from 3 sites including the primary cancer, distant metastasis, and lymph-node metastasis in 152 advanced CRC patients (cohort 2). KRAS exons 2 and 3 were investigated for mutations. Results In cohort 1, c-MYC gene amplification, defined by a c-MYC:centromere of chromosome 8 ratio ≥ 2.0, was detected in 31 (8.4%) of 367 patients. A c-MYC GCN gain, defined by ≥ 4.0 c-MYC copies/nucleus, was found in 63 (17.2%) patients and was associated with poor prognosis (P = 0.015). Multivariate Cox regression analysis showed that the hazard ratio for c-MYC GCN gain was 2.35 (95% confidence interval, 1.453–3.802; P < 0.001). In a subgroup of stage II-III CRC patients, c-MYC GCN gain was significantly associated with poor prognosis by univariate (P = 0.034) and multivariate (P = 0.040) analyses. c-MYC protein overexpression was observed in 201 (54.8%) out of 367 patients and weakly correlated with c-MYC GCN gain (ρ, 0.211). In cohort 2, the c-MYC genetic status was heterogenous in advanced CRC patients. Discordance between GCN gain in the primary tumor and either distant or lymph-node metastasis was 25.7% and 30.4%, respectively. A similar frequency for c-MYC GCN gain and amplification was observed in CRC patients with both wild-type and mutated KRAS. Conclusions c-MYC GCN gain was an independent factor for poor prognosis in consecutive CRC patients and in the stage II-III subgroup. Our findings indicate that the status of c-MYC may be helpful in predicting the patients’ outcome and for managing CRC patients. PMID:26426996

  8. Inversed relationship between CD44 variant and c-Myc due to oxidative stress-induced canonical Wnt activation

    SciTech Connect

    Yoshida, Go J. Saya, Hideyuki

    2014-01-10

    Highlights: •CD44 variant8–10 and c-Myc are inversely expressed in gastric cancer cells. •Redox-stress enhances c-Myc expression via canonical Wnt signal. •CD44v, but not CD44 standard, suppresses redox stress-induced Wnt activation. •CD44v expression promotes both transcription and proteasome degradation of c-Myc. •Inversed expression pattern between CD44v and c-Myc is often recognized in vivo. -- Abstract: Cancer stem-like cells express high amount of CD44 variant8-10 which protects cancer cells from redox stress. We have demonstrated by immunohistochemical analysis and Western blotting, and reverse-transcription polymerase chain reaction, that CD44 variant8-10 and c-Myc tend to show the inversed expression manner in gastric cancer cells. That is attributable to the oxidative stress-induced canonical Wnt activation, and furthermore, the up-regulation of the downstream molecules, one of which is oncogenic c-Myc, is not easily to occur in CD44 variant-positive cancer cells. We have also found out that CD44v8-10 expression is associated with the turn-over of the c-Myc with the experiments using gastric cancer cell lines. This cannot be simply explained by the model of oxidative stress-induced Wnt activation. CD44v8-10-positive cancer cells are enriched at the invasive front. Tumor tissue at the invasive area is considered to be composed of heterogeneous cellular population; dormant cancer stem-like cells with CD44v8-10 {sup high}/ Fbw7 {sup high}/ c-Myc {sup low} and proliferative cancer stem-like cells with CD44v8-10 {sup high}/ Fbw7 {sup low}/ c-Myc {sup high}.

  9. The anticancer activity and cellular repression of c-MYC by the G-quadruplex-stabilizing 11-piperazinyl quindoline is not dependent on direct targeting of the G-quadruplex in the c-MYC promoter

    PubMed Central

    Boddupally, Peda V. L.; Hahn, Seongmin; Beman, Cristina; De, Biswanath; Brooks, Tracy A.; Gokhale, Vijay; Hurley, Laurence H.

    2012-01-01

    This G-rich region of the c-MYC promoter has been shown to form a G-quadruplex structure, acting as a silencer element for c-MYC transcriptional control. In the present work, we have synthesized a series of 11-substituted quindoline analogs as c-MYC G-quadruplex–stabilizing compounds, and the cell-free and in vitro activity of these compounds were evaluated. Two lead compounds (4 and 12) demonstrated good cell-free profiles, and compound 4 (2-(4-(10H-indolo[3,2-b]quinolin-11-yl)piperazin-1-yl)-N,N-dimethylethanamine) significantly downregulated c-MYC expression. However, despite the good cell-free activity and the effect of these compounds on c-MYC gene expression, we have demonstrated, using a cellular assay in a Burkitt’s lymphoma cell line (CA46-specific), that these effects were not mediated through targeting the c-MYC G-quadruplex. Thus, caution should be used in assigning the effects of G-quadruplex-interactive compounds that lower c-MYC to direct targeting of these promoter elements unless this assay, or similar ones, demonstrates direct targeting of the G-quadruplex in cells. PMID:22691117

  10. Effects of Low-Dose Bisphenol A on DNA Damage and Proliferation of Breast Cells: The Role of c-Myc

    PubMed Central

    Pfeifer, Daniella; Chung, Young Min

    2015-01-01

    Background Humans are exposed to low-dose bisphenol A (BPA) through plastic consumer products and dental sealants containing BPA. Although a number of studies have investigated the mammary gland effects after high-dose BPA exposure, the study findings differ. Furthermore, there has been a lack of mechanistic studies. Objective The objective of this study was to investigate the effect and the mechanism of low-dose BPA in mammary gland cells. Methods We evaluated DNA damage following BPA exposure using the comet assay and immunofluorescence staining, and used cell counting and three-dimensional cultures to evaluate effects on proliferation. We examined the expressions of markers of DNA damage and cell-cycle regulators by immunoblotting and performed siRNA-mediated gene silencing to determine the role of c-Myc in regulating BPA’s effects. Results Low-dose BPA significantly promoted DNA damage, up-regulated c-Myc and other cell-cycle regulatory proteins, and induced proliferation in parallel in estrogen receptor-α (ERα)-negative mammary cells. Silencing c-Myc diminished these BPA-induced cellular events, suggesting that c-Myc is essential for regulating effects of BPA on DNA damage and proliferation in mammary cells. Conclusions Low-dose BPA exerted c-Myc–dependent genotoxic and mitogenic effects on ERα-negative mammary cells. These findings provide significant evidence of adverse effects of low-dose BPA on mammary cells. Citation Pfeifer D, Chung YM, Hu MC. 2015. Effects of low-dose bisphenol A on DNA damage and proliferation of breast cells: the role of c-Myc. Environ Health Perspect 123:1271–1279; http://dx.doi.org/10.1289/ehp.1409199 PMID:25933419

  11. Suppression of c-Myc is involved in multi-walled carbon nanotubes' down-regulation of ATP-binding cassette transporters in human colon adenocarcinoma cells

    SciTech Connect

    Wang, Zhaojing; Xu, Yonghong; Meng, Xiangning; Watari, Fumio; Liu, Hudan; Chen, Xiao

    2015-01-01

    Over-expression of ATP-binding cassette (ABC) transporters, a large family of integral membrane proteins that decrease cellular drug uptake and accumulation by active extrusion, is one of the major causes of cancer multi-drug resistance (MDR) that frequently leads to failure of chemotherapy. Carbon nanotubes (CNTs)-based drug delivery devices hold great promise in enhancing the efficacy of cancer chemotherapy. However, CNTs' effects on the ABC transporters remain under-investigated. In this study, we found that multiwalled carbon nanotubes (MWCNTs) reduced transport activity and expression of ABC transporters including ABCB1/Pgp and ABCC4/MRP4 in human colon adenocarcinoma Caco-2 cells. Proto-oncogene c-Myc, which directly regulates ABC gene expression, was concurrently decreased in MWCNT-treated cells and forced over-expression of c-Myc reversed MWCNTs' inhibitory effects on ABCB1 and ABCC4 expression. MWCNT-cell membrane interaction and cell membrane oxidative damage were observed. However, antioxidants such as vitamin C, β-mecaptoethanol and dimethylthiourea failed to antagonize MWCNTs' down-regulation of ABC transporters. These data suggest that MWCNTs may act on c-Myc, but not through oxidative stress, to down-regulate ABC transporter expression. Our findings thus shed light on CNTs' novel cellular effects that may be utilized to develop CNTs-based drug delivery devices to overcome ABC transporter-mediated cancer chemoresistance.

  12. [Advances Research on C-MYC Proto-oncogene in Multiple Myeloma -Review].

    PubMed

    Huang, He; Guo, Wen-Jian; Yao, Ron-Xin

    2016-08-01

    Multiple myeloma(MM) as one of the most common tumors of hmatologic system, is characterized by malignant proliferation of plasma cells, and the chemotherapy is the main therapeutic method. MM is an incurable disease because of drug-resistance of MM cells. Although the pathogenesis of MM remains unknown, the chromosome abnormalities exit in half of the patients, particularly the highly expressed gene C-MYC. Furthermore, plenty of clinical researches indicated a high expression level of C-MYC implied worse progression and/or poor prognosis of MM. Recently, the work exploiting the compounds targeting MYC has made substantial progress, even in the MM therapy. In this article, briefly the recent advances of the research on C-MYC proto-oncogene in multiple myeloma are reviewed. PMID:27531809

  13. Chemical intervention of the NM23-H2 transcriptional programme on c-MYC via a novel small molecule

    PubMed Central

    Shan, Chan; Lin, Jing; Hou, Jin-Qiang; Liu, Hui-Yun; Chen, Shuo-Bin; Chen, Ai-Chun; Ou, Tian-Miao; Tan, Jia-Heng; Li, Ding; Gu, Lian-Quan; Huang, Zhi-Shu

    2015-01-01

    c-MYC is an important oncogene that is considered as an effective target for anticancer therapy. Regulation of this gene's transcription is one avenue for c-MYC-targeting drug design. Direct binding to a transcription factor and generating the intervention of a transcriptional programme appears to be an effective way to modulate gene transcription. NM23-H2 is a transcription factor for c-MYC and is proven to be related to the secondary structures in the promoter. Here, we first screened our small-molecule library for NM23-H2 binders and then sifted through the inhibitors that could target and interfere with the interaction process between NM23-H2 and the guanine-rich promoter sequence of c-MYC. As a result, a quinazolone derivative, SYSU-ID-01, showed a significant interference effect towards NM23-H2 binding to the guanine-rich promoter DNA sequence. Further analyses of the compound–protein interaction and the protein–DNA interaction provided insight into the mode of action for SYSU-ID-01. Cellular evaluation results showed that SYSU-ID-01 could abrogate NM23-H2 binding to the c-MYC promoter, resulting in downregulation of c-MYC transcription and dramatically suppressed HeLa cell growth. These findings provide a new way of c-MYC transcriptional control through interfering with NM23-H2 binding to guanine-rich promoter sequences by small molecules. PMID:26117539

  14. Hsa-let-7a functions as a tumor suppressor in renal cell carcinoma cell lines by targeting c-myc

    SciTech Connect

    Liu, Yongchao; Yin, Bingde; Zhang, Changcun; Zhou, Libin; Fan, Jie

    2012-01-06

    Highlights: Black-Right-Pointing-Pointer This study is the first to test the let-7a/c-myc loop in renal cell carcinoma cell lines. Black-Right-Pointing-Pointer Let-7a down-regulated c-myc in three renal cell carcinoma cell lines. Black-Right-Pointing-Pointer c-myc target genes were down-regulated because of the let-7a-mediated down-regulation of c-myc. Black-Right-Pointing-Pointer The let-7a/c-myc loop has a significant function in renal cell carcinoma cell lines. -- Abstract: Widespread functions of the c-myc pathway play a crucial role in renal cell carcinoma (RCC) carcinogenesis. Thus, we evaluated the connection between proto-oncogenic c-myc and anti-neoplastic hsa-let-7a (let-7a) in RCC cell lines. The levels of c-myc and let-7a in 3 RCC cell lines (769P, Caki-1 and 786O) were measured after transfecting the cells with let-7a mimics or a negative control. The change in c-myc protein level was confirmed by Western blot. The anti-neoplastic function of let-7a was evaluated using cell counting kit-8 (CCK-8) for proliferation analysis and cell flow cytometry for cell cycle analysis. The changes of downstream targets of c-myc were measured using reverse transcription quantitative real-time PCR (qRT-PCR). Our results suggest for the first time that let-7a acts as a tumor suppressor in RCC cell lines by down-regulating c-myc and c-myc target genes such as proliferating cell nuclear antigen (PCNA), cyclin D1 (CCND1) and the miR17-92 cluster, which is accompanied by proliferation inhibition and cell cycle arrest.

  15. HIF and c-Myc: sibling rivals for control of cancer cell metabolism and proliferation

    PubMed Central

    Gordan, John D.; Thompson, Craig B.; Simon, M. Celeste

    2011-01-01

    O2 deprivation (hypoxia) and cellular proliferation engage opposite cellular pathways, yet often coexist during tumor growth. The ability of cells to grow during hypoxia results in part from crosstalk between hypoxia inducible factors (HIFs) and the proto-oncogene c-Myc. Acting alone, HIF and c-Myc partially regulate complex adaptations undertaken by tumor cells growing in low O2. However, acting in concert, these transcription factors reprogram metabolism, protein synthesis and cell cycle progression, to “fine tune” adaptive responses to hypoxic environments. PMID:17692803

  16. Human RNA polymerase II associated factor 1 complex promotes tumorigenesis by activating c-MYC transcription in non-small cell lung cancer.

    PubMed

    Zhi, Xiuyi; Giroux-Leprieur, Etienne; Wislez, Marie; Hu, Mu; Zhang, Yi; Shi, Huaiyin; Du, Kaiqi; Wang, Lei

    2015-10-01

    Human RNA polymerase II (RNAPII)-associated factor 1 complex (hPAF1C) plays a crucial role in protein-coding gene transcription. Overexpression of hPAF1C has been implicated in the initiation and progression of various human cancers. However, the molecular pathways involved in tumorigenesis through hPAF1C remain to be elucidated. The current study suggested hPAF1C expression as a prognostic biomarker for early stage non-small cell lung cancer (NSCLC) and patients with low hPAF1C expression levels had significantly better overall survival. Furthermore, the expression of hPAF1C was found to be positively correlated with c-MYC expression in patient tumor samples and in cancer cell lines. Mechanistic studies indicated that hPAF1C could promote lung cancer cell proliferation through regulating c-MYC transcription. These results demonstrated the prognostic value of hPAF1C in early-stage NSCLC and the role of hPAF1C in the transcriptional regulation of c-MYC oncogene during NSCLC tumorigenesis. PMID:26282204

  17. Frequent co-amplification and co-operation between C-MYC and PVT1 oncogenes promote malignant pleural mesothelioma

    PubMed Central

    Riquelme, Erick; Suraokar, Milind B.; Rodriguez, Jaime; Mino, Barbara; Lin, Heather Y.; Rice, David C.; Tsao, Anne; Wistuba, Ignacio I.

    2014-01-01

    Introduction Malignant pleural mesothelioma (MPM) is a deadly disease with poor prognosis and few treatment options. We characterized and elucidate the roles of C-MYC and PVT1 involved in the pathogenesis of MPM. Methods We used siRNA-mediated knockdown in MPM cell lines to determine the effect of C-MYC and PVT1 abrogation on MPM cells undergoing apoptosis, proliferation, and cisplatin sensitivity. We also characterized the expression of microRNAs (miRNAs) spanning the PVT1 region in MPM cell lines. Copy number analysis was measured by quantitative PCR and fluorescence in situ hybridization. Results Copy number analysis revealed copy number gains (CNGs) in chromosomal region 8q24 in six of twelve MPM cell lines. MicroRNA analysis showed high miR-1204 expression in MSTO-211H cell lines with ≥4 copies of PVT1. Knockdown by siRNA showed increased PARP-C levels in MSTO-211H transfected with siPVT1 but not in cells transfected with siC-MYC. C-MYC and PVT1 knockdown reduced cell proliferation and increased sensitivity to cisplatin. Analysis of the expression of apoptosis-related genes in the MSTO-211H cell line suggested that C-MYC maintains a balance between pro-apoptotic and anti-apoptotic gene expression, whereas PVT1 and to a lesser extent miR-1204, upregulate pro-apoptotic genes and downregulate anti-apoptotic genes. FISH analysis of MPM tumor specimens showed a high frequency of both CNGs (11/75) and trisomy (three copies; 11/75) for the C-MYC locus. Conclusion Our results suggest that C-MYC and PVT1 copy number gain promotes a malignant phenotype of MPM, with C-MYC CNG stimulating cell proliferation and PVT1 both stimulating proliferation and inhibiting apoptosis. PMID:24926545

  18. Absence of missense mutations in activated c-myc genes in avian leukosis virus-induced B-cell lymphomas

    SciTech Connect

    Hahn, M.; Hayward, W.S.

    1988-06-01

    The authors determined the nucleotide sequences of two independent DNA clones which contained the activated c-myc genes from avian leukosis virus-induced B-cell lymphomas. Neither of these c-myce genes contained missense mutations. This strongly supports the notion that the c-myc photo-oncogene in avian leukosis virus-induced B-cell lymphomas can be oncogenically activated by altered expression of the gene without a change in the primary structure of the gene product.

  19. C-Myc negatively controls the tumor suppressor PTEN by upregulating miR-26a in glioblastoma multiforme cells

    SciTech Connect

    Guo, Pin; Nie, Quanmin; Lan, Jin; Ge, Jianwei; Qiu, Yongming; Mao, Qing

    2013-11-08

    Highlights: •The c-Myc oncogene directly upregulates miR-26a expression in GBM cells. •ChIP assays demonstrate that c-Myc interacts with the miR-26a promoter. •Luciferase reporter assays show that PTEN is a specific target of miR-26a. •C-Myc–miR-26a suppression of PTEN may regulate the PTEN/AKT pathway. •Overexpression of c-Myc enhances the proliferative capacity of GBM cells. -- Abstract: The c-Myc oncogene is amplified in many tumor types. It is an important regulator of cell proliferation and has been linked to altered miRNA expression, suggesting that c-Myc-regulated miRNAs might contribute to tumor progression. Although miR-26a has been reported to be upregulated in glioblastoma multiforme (GBM), the mechanism has not been established. We have shown that ectopic expression of miR-26a influenced cell proliferation by targeting PTEN, a tumor suppressor gene that is inactivated in many common malignancies, including GBM. Our findings suggest that c-Myc modulates genes associated with oncogenesis in GBM through deregulation of miRNAs via the c-Myc–miR-26a–PTEN signaling pathway. This may be of clinical relevance.

  20. Wogonin inhibits multiple myeloma-stimulated angiogenesis via c-Myc/VHL/HIF-1α signaling axis

    PubMed Central

    Wang, Xiao-Ping; An, Teng; Tao, Lei; Zhou, Yu-Xin; Huang, Yu-Jie; Chen, Bao-An; Li, Zhi-Yu; You, Qi-Dong; Guo, Qing-Long; Wu, Zhao-Qiu

    2016-01-01

    Angiogenesis is associated with the progression of multiple myeloma (MM). Wogonin is an active mono-flavonoid with remarkable antitumor activity. However, its impact on MM-stimulated angiogenesis remains largely unknown. Here, we demonstrated that wogonin decreased expression and secretion of pro-angiogenic factors in MM cells via c-Myc/HIF-1α signaling axis, reducing MM-stimulated angiogenesis and MM cell proliferation in vivo. Overexpression of c-Myc in MM cells disrupted the balance between VHL SUMOylation and ubiquitination, and thus inhibited proteasome-mediated HIF-1α degradation. Impaired function of VHL ubiquitination complex in c-Myc-overexpressing cells was fully reversed by wogonin treatment via increasing HIF-1α-VHL interaction and promoting HIF-1α degradation. Collectively, our in vitro and in vivo studies reveal for the first time that wogonin represses MM-stimulated angiogenesis and tumor progression via c-Myc/VHL/HIF-1α signaling axis. PMID:26735336

  1. BET protein inhibitor JQ1 attenuates Myc-amplified MCC tumor growth in vivo.

    PubMed

    Shao, Qiang; Kannan, Aarthi; Lin, Zhenyu; Stack, Brendan C; Suen, James Y; Gao, Ling

    2014-12-01

    Merkel cell carcinoma (MCC) is an aggressive neuroendocrine tumor of the skin currently with no cure. In this study, we have first demonstrated that c-Myc overexpression is common in MCC. By targeting c-Myc, bromodomain inhibitors have demonstrated antitumor efficacy in several preclinical human cancer models. Thus, we interrogated the role of c-Myc inhibition in MCC with c-Myc amplification by using the BET inhibitor JQ1. We have uncovered that c-Myc can be regulated by JQ1 in MCC cells with pathologic c-Myc activation. Moreover, JQ1 potently abrogates c-Myc expression in MCC cells and causes marked G1 cell-cycle arrest. Mechanistically, JQ1-induced cell-cycle arrest coincides with downregulation of cyclin D1 and upregulation of p21, p27, and p57, whereas JQ1 exerts no effect on apoptosis in MCC cells. Further knockdown of p21, p27, or p57 by shRNA partially protects cells from JQ1-induced cell-cycle arrest. In addition, c-Myc knockdown by shRNA generates significant cell-cycle arrest, suggesting that c-Myc overexpression plays a role in MCC pathogenesis. Most importantly, JQ1 significantly attenuates tumor growth in xenograft MCC mouse models. Our results provide initial evidence, indicating the potential clinical utility of BET protein inhibitors in the treatment of MCC with pathologic activation of c-Myc. PMID:25277525

  2. Epigenetic mechanisms regulate placental c-myc and hTERT in normal and pathological pregnancies; c-myc as a novel fetal DNA epigenetic marker for pre-eclampsia.

    PubMed

    Rahat, Beenish; Hamid, Abid; Ahmad Najar, Rauf; Bagga, Rashmi; Kaur, Jyotdeep

    2014-10-01

    Placental development is known for its resemblance with tumor development, such as in the expression of oncogenes (c-myc) and telomerase (hTERT). The expression of c-myc and hTERT is up-regulated during early pregnancy and gestational trophoblastic diseases (GTDs). To determine the role of DNA methylation [via methylation-sensitive high resolution melting (MS-HRM)] and histone modifications [via chromatin immunoprecipitation (ChIP assay)] in regulating the differential expression of c-myc and hTERT during normal gestation and their dysregulation during placental disorders, we obtained placental samples from 135 pregnant women, in five groups: normal first, second and third trimester (n = 30 each), pre-eclamptic pregnancy (n = 30) and molar pregnancy (n = 15). Two placental cell lines (JEG-3 and HTR-8/SVneo) and isolated first-trimester cytotrophoblasts were also studied. Quantitative RT-PCR revealed decreased mRNA expression levels of c-myc and hTERT, which were associated with a higher level of H3K9me3 (1.5-fold, P < 0.05) and H3K27me3 (1.9-fold, P < 0.05), respectively, in third-trimester placental villi versus first-trimester villi. A significantly lower level of H3K27me3 in molar placenta was associated with a higher mRNA expression of c-myc and hTERT. The development of pre-eclampsia (PE) was associated with increased methylation (P < 0.001) and H3K27me3 (P < 0.01) at the c-myc promoter and reduced H3K9me3 (P < 0.01) and H3K27me3 (P < 0.05) at the hTERT promoter. Further, mRNA expression of c-myc and hTERT was strongly correlated in molar villi (r = 0.88, P < 0.01) and JEG-3 cells (r = 0.99, P < 0.02). Moreover, on the basis of methylation data, we demonstrate the potential of c-myc as a fetal DNA epigenetic marker for pre-eclamptic pregnancies. Thus we suggest a role for epigenetic mechanisms in regulating differential expression of c-myc and hTERT during placental development and use of the c-myc promoter region as a potential fetal DNA marker in the case of

  3. The c-MYC-ABCB5 axis plays a pivotal role in 5-fluorouracil resistance in human colon cancer cells

    PubMed Central

    Kugimiya, Naruji; Nishimoto, Arata; Hosoyama, Tohru; Ueno, Koji; Enoki, Tadahiko; Li, Tao-Sheng; Hamano, Kimikazu

    2015-01-01

    c-MYC overexpression is frequently observed in various cancers including colon cancer and regulates many biological activities such as aberrant cell proliferation, apoptosis, genomic instability, immortalization and drug resistance. However, the mechanism by which c-MYC confers drug resistance remains to be fully elucidated. In this study, we found that the c-MYC expression level in primary colorectal cancer tissues correlated with the recurrence rate following 5-fluorouracil (5-FU)-based adjuvant chemotherapy. Supporting this finding, overexpression of exogenous c-MYC increased the survival rate following 5-FU treatment in human colon cancer cells, and knockdown of endogenous c-MYC decreased it. Furthermore, c-MYC knockdown decreased the expression level of ABCB5, which is involved in 5-FU resistance. Using a chromatin immunoprecipitation assay, we found that c-MYC bound to the ABCB5 promoter region. c-MYC inhibitor (10058-F4) treatment inhibited c-MYC binding to the ABCB5 promoter, leading to a decrease in ABCB5 expression level. ABCB5 knockdown decreased the survival rate following 5-FU treatment as expected, and the ABCB5 expression level was increased in 5-FU-resistant human colon cancer cells. Finally, using a human colon cancer xenograft murine model, we found that the combined 5-FU and 10058-F4 treatment significantly decreased tumorigenicity in nude mice compared with 5-FU or 10058-F4 treatment alone. 10058-F4 treatment decreased the ABCB5 expression level in the presence or absence of 5-FU. In contrast, 5-FU treatment alone increased the ABCB5 expression level. Taken together, these results suggest that c-MYC confers resistance to 5-FU through regulating ABCB5 expression in human colon cancer cells. PMID:25689483

  4. Evidence that the familial adenomatous polyposis gene is involved in a subset of colon cancers with a complementable defect in c-myc regulation

    SciTech Connect

    Erisman, M.D.; Scott, J.K.; Astrin, S.M. )

    1989-06-01

    Human colorectal carcinomas frequently express elevated levels of c-myc mRNA in the absence of a gross genetic change at the c-myc locus. To test the hypothesis that these tumors are defective in a gene function necessary for the regulation of c-myc expression, the authors fused an osteosarcoma cell line that exhibits normal c-myc regulation with two colon carcinoma cell lines that express deregulated levels of c-myc mRNA. Since rates of c-myc mRNA turnover in the colon carcinoma cells were found to be comparable to those in normal cells, increased message stability cannot account for the increased steady-state levels of transcripts. These finding suggest that loss of function of a trans-acting regulator is responsible for the deregulation of c-myc expression in a major fraction of colorectal carcinomas. Analysis of restriction fragment length polymorphisms in tumor/normal tissue pairs from patients with primary colorectal lesions indicated that deregulation of c-myc expression in the tumors is correlated with frequent loss of alleles of syntenic markers on chromosome 5q. Chromosome 5q is the region known to contain the gene for familial adenomatous polyposis, an inherited predisposition to colon cancer. These findings, together with the arlier finding that the colonic distribution of tumors exhibiting deregulated c-myc expression is similar to that reported for familial polyposis, provide evidence that loss of function of the familial adenomatous polyposis gene is involved in a subset of colorectal cancers in which c-myc expression is deregulated.

  5. The Guanine-Quadruplex Structure in the Human c-myc Gene's Promoter Is Converted into B-DNA Form by the Human Poly(ADP-Ribose)Polymerase-1

    PubMed Central

    Fekete, Anna; Kenesi, Erzsebet; Hunyadi-Gulyas, Eva; Durgo, Hajnalka; Berko, Barbara; Dunai, Zsuzsanna A.; Bauer, Pal I.

    2012-01-01

    The important regulatory role of the guanine-quadruplex (GQ) structure, present in the nuclease hypersensitive element (NHE) III1 region of the human c-myc (h c-myc) gene's promoter, in the regulation of the transcription of that gene has been documented. Here we present evidences, that the human nuclear poly(ADP-ribose)polymerase-1 (h PARP-1) protein participates in the regulation of the h c-myc gene expression through its interaction with this GQ structure, characterized by binding assays, fluorescence energy transfer (FRET) experiments and by affinity pull-down experiments in vitro, and by chromatin immunoprecipitation (ChIP)-qPCR analysis and h c-myc-promoter-luciferase reporter determinations in vivo. We surmise that h PARP-1 binds to the GQ structure and participates in the conversion of that structure into the transcriptionally more active B-DNA form. The first Zn-finger structure present in h PARP-1 participates in this interaction. PARP-1 might be a new member of the group of proteins participating in the regulation of transcription through their interactions with GQ structures present in the promoters of different genes. PMID:22880082

  6. c-MYC responds to glucose deprivation in a cell-type-dependent manner.

    PubMed

    Wu, S; Yin, X; Fang, X; Zheng, J; Li, L; Liu, X; Chu, L

    2015-01-01

    Metabolic reprogramming supports cancer cells' demands for rapid proliferation and growth. Previous work shows that oncogenes, such as MYC, hypoxia-inducible factor 1 (HIF1), have a central role in driving metabolic reprogramming. A lot of metabolic enzymes, which are deregulated in most cancer cells, are the targets of these oncogenes. However, whether metabolic change affects these oncogenes is still unclear. Here we show that glucose deprivation (GD) affects c-MYC protein levels in a cell-type-dependent manner regardless of P53 mutation status. GD dephosphorylates and then decreases c-MYC protein stability through PI3K signaling pathway in HeLa cells, but not in MDA-MB-231 cells. Role of c-MYC in sensitivity of GD also varies with cell types. c-MYC-mediated glutamine metabolism partially improves the sensitivity of GD in MDA-MB-231 cells. Our results reveal that the heterogeneity of cancer cells in response to metabolic stress should be considered in metabolic therapy for cancer. PMID:27551483

  7. c-MYC responds to glucose deprivation in a cell-type-dependent manner

    PubMed Central

    Wu, S; Yin, X; Fang, X; Zheng, J; Li, L; Liu, X; Chu, L

    2015-01-01

    Metabolic reprogramming supports cancer cells’ demands for rapid proliferation and growth. Previous work shows that oncogenes, such as MYC, hypoxia-inducible factor 1 (HIF1), have a central role in driving metabolic reprogramming. A lot of metabolic enzymes, which are deregulated in most cancer cells, are the targets of these oncogenes. However, whether metabolic change affects these oncogenes is still unclear. Here we show that glucose deprivation (GD) affects c-MYC protein levels in a cell-type-dependent manner regardless of P53 mutation status. GD dephosphorylates and then decreases c-MYC protein stability through PI3K signaling pathway in HeLa cells, but not in MDA-MB-231 cells. Role of c-MYC in sensitivity of GD also varies with cell types. c-MYC-mediated glutamine metabolism partially improves the sensitivity of GD in MDA-MB-231 cells. Our results reveal that the heterogeneity of cancer cells in response to metabolic stress should be considered in metabolic therapy for cancer. PMID:27551483

  8. Recessive genetic deregulation abrogates c-myc suppression by interferon and is implicated in oncogenesis

    SciTech Connect

    Kimchi, A.; Resnitzky, D.; Ber, R.; Gat, G.

    1988-07-01

    Previously the authors demonstrated that many hematopoietic tumor cells are resistant to the inhibitory effects that interferon exerts on c-myc mRNA expression without losing other receptor-mediated intracellular responses. They report here that this partial resistance was overridden in two independent stable somatic cell hybrids prepared by fusion between sensitive and resistant cells. The c-myc mRNA transcribed from the active allele of the resistant parent cell was reduced by interferon within the context of the cell hybrid. It was therefore concluded that changes in the cis-acting sequences of c-myc were not involved in this type of relaxed regulation and that resistance resulted rather from inactivation or loss of postreceptor elements which operate in trans. The growth-stimulating effect that this genetic deregulation might have on cells was tested in experimental systems of cell differentiation in which an autocrine interferon is produced. For that purpose the authors isolated variant clones of M1 myeloid cells which were partially resistant to alpha and beta interferons and tested their growth behaviour during in vitro-induced differentiation. The resistant clones displayed higher proliferative activity on days 2 and 3 of differentiation than did the sensitive clones, which stopped proliferating. The loss of c-myc responses to the self-produced interferon disrupted the normal cessation of growth during differentiation and therefore might lead cells along the pathway of neoplasia.

  9. Selective recognition of c-MYC G-quadruplex DNA using prolinamide derivatives.

    PubMed

    Chauhan, Ajay; Paladhi, Sushovan; Debnath, Manish; Dash, Jyotirmayee

    2016-06-28

    Herein we report the design, synthesis, biophysical and biological evaluation of triazole containing prolinamide derivatives as selective c-MYC G-quadruplex binding ligands. A modular synthetic route has been devised for prolinamide derivatives using a copper(i) catalyzed azide-alkyne cycloaddition (CuAAC). The Förster resonance energy transfer (FRET) melting assay indicates that prolinamide trimers can significantly stabilize G-quadruplex structures over duplex DNA compared to prolinamide dimers. The fluorescent intercalator displacement (FID) assay shows that a trimer with prolinamide side chains at the para-position of the benzene ring can discriminate between different quadruplex structures and exhibits the highest binding affinity towards the c-MYC G-quadruplex structure. Molecular modeling studies reveal that the prolinamide trimer stacks upon the terminal G-quartet of the c-MYC G-quadruplex. Atomic force microscopy (AFM) analysis reveals that the tris-prolinamide ligand can be used to regulate the assembly of novel supramolecular nanoarchitectures. Further, in vitro cellular studies with human hepatocellular carcinoma (HepG2) cells indicate that the tris-prolinamide derivatives can inhibit cell proliferation and reduce c-MYC expression in cancer cells. PMID:26963597

  10. C-Myc regulation by costimulatory signals modulates the generation of CD8+ memory T cells during viral infection

    PubMed Central

    Haque, Mohammad; Song, Jianyong; Fino, Kristin; Wang, Youfei; Sandhu, Praneet; Song, Xinmeng; Norbury, Christopher; Ni, Bing; Fang, Deyu; Salek-Ardakani, Shahram; Song, Jianxun

    2016-01-01

    The signalling mechanisms of costimulation in the development of memory T cells remain to be clarified. Here, we show that the transcription factor c-Myc in CD8+ T cells is controlled by costimulatory molecules, which modulates the development of memory CD8+ T cells. C-Myc expression was dramatically reduced in Cd28−/− or Ox40−/− memory CD8+ T cells, and c-Myc over-expression substantially reversed the defects in the development of T-cell memory following viral infection. C-Myc regulated the expression of survivin, an inhibitor of apoptosis, which promoted the generation of virus-specific memory CD8+ T cells. Moreover, over-expression of survivin with bcl-xL, a downstream molecule of NF-κB and intracellular target of costimulation that controls survival, in Cd28−/− or Ox40−/− CD8+ T cells, reversed the defects in the generation of memory T cells in response to viral infection. These results identify c-Myc as a key controller of memory CD8+ T cells from costimulatory signals. PMID:26791245

  11. Therapeutic potential of targeting IRES-dependent c-myc translation in multiple myeloma cells during ER stress.

    PubMed

    Shi, Y; Yang, Y; Hoang, B; Bardeleben, C; Holmes, B; Gera, J; Lichtenstein, A

    2016-02-25

    Protein translation is inhibited by the unfolded protein response (UPR)-induced eIF-2α phosphorylation to protect against endoplasmic reticulum (ER) stress. In addition, we found additional inhibition of protein translation owing to diminished mTORC1 (mammalian target of rapamycin complex1) activity in ER-stressed multiple myeloma (MM) cells. However, c-myc protein levels and myc translation was maintained. To ascertain how c-myc was maintained, we studied myc IRES (internal ribosome entry site) function, which does not require mTORC1 activity. Myc IRES activity was upregulated in MM cells during ER stress induced by thapsigargin, tunicamycin or the myeloma therapeutic bortezomib. IRES activity was dependent on upstream MAPK (mitogen-activated protein kinase) and MNK1 (MAPK-interacting serine/threonine kinase 1) signaling. A screen identified hnRNP A1 (A1) and RPS25 as IRES-binding trans-acting factors required for ER stress-activated activity. A1 associated with RPS25 during ER stress and this was prevented by an MNK inhibitor. In a proof of principle, we identified a compound that prevented binding of A1 to the myc IRES and specifically inhibited myc IRES activity in MM cells. This compound, when used alone, was not cytotoxic nor did it inhibit myc translation or protein expression. However, when combined with ER stress inducers, especially bortezomib, a remarkable synergistic cytotoxicity ensued with associated inhibition of myc translation and expression. These results underscore the potential for targeting A1-mediated myc IRES activity in MM cells during ER stress. PMID:25961916

  12. The transcription factor c-Myc enhances KIR gene transcription through direct binding to an upstream distal promoter element

    PubMed Central

    Cichocki, Frank; Hanson, Rebecca J.; Lenvik, Todd; Pitt, Michelle; McCullar, Valarie; Li, Hongchuan; Anderson, Stephen K.

    2009-01-01

    The killer cell immunoglobulin-like receptor (KIR) repertoire of natural killer (NK) cells determines their ability to detect infected or transformed target cells. Although epigenetic mechanisms play a role in KIR gene expression, work in the mouse suggests that other regulatory elements may be involved at specific stages of NK-cell development. Here we report the effects of the transcription factor c-Myc on KIR expression. c-Myc directly binds to, and promotes transcription from, a distal element identified upstream of most KIR genes. Binding of endogenous c-Myc to the distal promoter element is significantly enhanced upon interleukin-15 (IL-15) stimulation in peripheral blood NK cells and correlates with an increase in KIR transcription. In addition, the overexpression of c-Myc during NK-cell development promotes transcription from the distal promoter element and contributes to the overall transcription of multiple KIR genes. Our data demonstrate the significance of the 5′ promoter element upstream of the conventional KIR promoter region and support a model whereby IL-15 stimulates c-Myc binding at the distal KIR promoter during NK-cell development to promote KIR transcription. This finding provides a direct link between NK-cell activation signals and KIR expression required for acquisition of effector function during NK-cell education. PMID:18987359

  13. Inhibition of c-MYC with involvement of ERK/JNK/MAPK and AKT pathways as a novel mechanism for shikonin and its derivatives in killing leukemia cells

    PubMed Central

    Zhao, Qiaoli; Assimopoulou, Andreana N.; Klauck, Sabine M.; Damianakos, Harilaos; Chinou, Ioanna; Kretschmer, Nadine; Rios, José-Luis; Papageorgiou, Vassilios P.; Bauer, Rudolf; Efferth, Thomas

    2015-01-01

    Leukemia remains life-threatening despite remarkable advances in chemotherapy. The poor prognosis and drug resistance are challenging treatment. Novel drugs are urgently needed. Shikonin, a natural naphthoquinone, has been previously shown by us to be particularly effective towards various leukemia cell lines compared to solid tumors. However, the underlying mechanisms are still poorly understood. Here, we investigated shikonin and 14 derivatives on U937 leukemia cells. Four derivatives (isobutyrylshikonin, 2-methylbutyrylshikonin, isovalerylshikonin and β,β-dimethylacrylshikonin) were more active than shikonin. AnnexinV-PI analysis revealed that shikonins induced apoptosis. Cell cycle G1/S check point regulation and the transcription factor c-MYC, which plays a vital role in cell cycle regulation and proliferation, were identified as the most commonly down-regulated mechanisms upon treatment with shikonins in mRNA microarray hybridizations. Western blotting and DNA-binding assays confirmed the inhibition of c-MYC expression and transcriptional activity by shikonins. Reduction of c-MYC expression was closely associated with deregulated ERK, JNK MAPK and AKT activity, indicating their involvement in shikonin-triggered c-MYC inactivation. Molecular docking studies revealed that shikonin and its derivatives bind to the same DNA-binding domain of c-MYC as the known c-MYC inhibitors 10058-F4 and 10074-G5. This finding indicates that shikonins bind to c-MYC. The effect of shikonin on U937 cells was confirmed in other leukemia cell lines (Jurkat, Molt4, CCRF-CEM, and multidrug-resistant CEM/ADR5000), where shikonin also inhibited c-MYC expression and influenced phosphorylation of AKT, ERK1/2, and SAPK/JNK. In summary, inhibition of c-MYC and related pathways represents a novel mechanism of shikonin and its derivatives to explain their anti-leukemic activity. PMID:26472107

  14. Inhibition of c-MYC with involvement of ERK/JNK/MAPK and AKT pathways as a novel mechanism for shikonin and its derivatives in killing leukemia cells.

    PubMed

    Zhao, Qiaoli; Assimopoulou, Andreana N; Klauck, Sabine M; Damianakos, Harilaos; Chinou, Ioanna; Kretschmer, Nadine; Rios, José-Luis; Papageorgiou, Vassilios P; Bauer, Rudolf; Efferth, Thomas

    2015-11-17

    Leukemia remains life-threatening despite remarkable advances in chemotherapy. The poor prognosis and drug resistance are challenging treatment. Novel drugs are urgently needed. Shikonin, a natural naphthoquinone, has been previously shown by us to be particularly effective towards various leukemia cell lines compared to solid tumors. However, the underlying mechanisms are still poorly understood. Here, we investigated shikonin and 14 derivatives on U937 leukemia cells. Four derivatives (isobutyrylshikonin, 2-methylbutyrylshikonin, isovalerylshikonin and β,β-dimethylacrylshikonin) were more active than shikonin. AnnexinV-PI analysis revealed that shikonins induced apoptosis. Cell cycle G1/S check point regulation and the transcription factor c-MYC, which plays a vital role in cell cycle regulation and proliferation, were identified as the most commonly down-regulated mechanisms upon treatment with shikonins in mRNA microarray hybridizations. Western blotting and DNA-binding assays confirmed the inhibition of c-MYC expression and transcriptional activity by shikonins. Reduction of c-MYC expression was closely associated with deregulated ERK, JNK MAPK and AKT activity, indicating their involvement in shikonin-triggered c-MYC inactivation. Molecular docking studies revealed that shikonin and its derivatives bind to the same DNA-binding domain of c-MYC as the known c-MYC inhibitors 10058-F4 and 10074-G5. This finding indicates that shikonins bind to c-MYC. The effect of shikonin on U937 cells was confirmed in other leukemia cell lines (Jurkat, Molt4, CCRF-CEM, and multidrug-resistant CEM/ADR5000), where shikonin also inhibited c-MYC expression and influenced phosphorylation of AKT, ERK1/2, and SAPK/JNK. In summary, inhibition of c-MYC and related pathways represents a novel mechanism of shikonin and its derivatives to explain their anti-leukemic activity. PMID:26472107

  15. MiR-449c targets c-Myc and inhibits NSCLC cell progression.

    PubMed

    Miao, Li-Jun; Huang, Shi-Fu; Sun, Zhen-Tao; Gao, Zeng-Yan; Zhang, Rui-Xia; Liu, Ying; Wang, Jing

    2013-05-01

    MicroRNAs (miRNA) play an important role in tumorigenesis, proliferation, and differentiation. Altered miRNA expression in cancer indicates that miRNAs can function as tumor suppressors or oncogenes. MiR-449c downregulation in non-small cell lung cancer (NSCLC) compared with normal lung tissues was investigated in this study. NSCLC cell proliferation and invasion assays indicate that transfection of miR-449c expression plasmid inhibits the proliferation and invasion ability of NCI-H23 and NCI-H838 cells. In addition, miR-449c overexpression could suppress tumor growth in vivo. Morever, c-Myc was identified as a direct target gene of miR-449c. These findings clearly suggest that miR-449c downregulation and c-Myc amplification may be involved in the development of NSCLC. PMID:23507140

  16. Aurora kinase A mediates c-Myc's oncogenic effects in hepatocellular carcinoma.

    PubMed

    Lu, Longfeng; Han, Han; Tian, Yuan; Li, Wenjuan; Zhang, Jinxiang; Feng, Maohui; Li, Youjun

    2015-11-01

    Dysregulation of c-Myc (Myc) has been shown to contribute to progression of hepatocellular carcinoma, however, the detailed molecular mechanism remains poorly understood. Here, we report that Myc binds to the Aurora kinase A (Aurka) promoter and induces expression of Aurka in HCC cells. Increased expression of Aurka correlates with that of Myc in HCC. Nuclear accumulation of Aurka was confirmed by subcellular protein fractionation and immunoblot experiments in HCC cells. Myc inhibition decreases the nuclear accumulation of Aurka in HCC cells. Also Aurka accumulating in the nucleus up-regulates Myc transcription by binding the Myc promoter containing the highly conserved CCCTCCCCA in the NHE region of the CpG islands. Inhibition of Myc or Aurka diminishes the malignant phenotypes of HCC cells by down-regulating some common target genes. Also Aurka and Myc mediates the effects of each other, at least partially, on proliferation, anchorage-independent soft agar growth, and ATP production. Blocking Aurka in an orthotopic model significantly impairs tumor growth in mice. These results identify a Myc-Aurka feedback loop in which Myc and Aurka regulate expression of each other at the transcriptional level and both play an important role in hepatocarcinogenesis. PMID:25284017

  17. AMBRA1 links autophagy to cell proliferation and tumorigenesis by promoting c-MYC dephosphorylation and degradation

    PubMed Central

    Cianfanelli, Valentina; Fuoco, Claudia; Lorente, Mar; Salazar, Maria; Quondamatteo, Fabio; Gherardini, Pier Federico; De Zio, Daniela; Nazio, Francesca; Antonioli, Manuela; D’Orazio, Melania; Skobo, Tatjana; Bordi, Matteo; Rohde, Mikkel; Dalla Valle, Luisa; Helmer-Citterich, Manuela; Gretzmeier, Christine; Dengjel, Joern; Fimia, Gian Maria; Piacentini, Mauro; Di Bartolomeo, Sabrina; Velasco, Guillermo; Cecconi, Francesco

    2016-01-01

    Inhibition of a main regulator of cell metabolism, the protein kinase mTOR, induces autophagy and inhibits cell proliferation. However, the molecular pathways involved in the cross-talk between these two mTOR-dependent cell processes are largely unknown. Here we show that the scaffold protein AMBRA1, a member of the autophagy signalling network and a downstream target of mTOR, regulates cell proliferation by facilitating the dephosphorylation and degradation of the proto-oncogene C-MYC. We found that AMBRA1 favors the interaction between C-MYC and its phosphatase PP2A and that, when mTOR is inhibited, it enhances PP2A activity on this specific target, thereby reducing the cell division rate. As expected, such a de-regulation of C-MYC correlates with increased tumorigenesis in AMBRA1-defective systems, thus supporting a role for AMBRA1 as a haploinsufficient tumour suppressor gene. PMID:25438055

  18. Haploinsufficiency of the c-myc transcriptional repressor FIR, as a dominant negative-alternative splicing model, promoted p53-dependent T-cell acute lymphoblastic leukemia progression by activating Notch1

    PubMed Central

    Rahmutulla, Bahityar; Tanaka, Nobuko; Ishige, Takayuki; Satoh, Mamoru; Hoshino, Tyuji; Miyagi, Satoru; Mori, Takeshi; Itoga, Sakae; Shimada, Hideaki; Tomonaga, Takeshi; Kito, Minoru; Nakajima-Takagi, Yaeko; Kubo, Shuji; Nakaseko, Chiaki; Hatano, Masahiko; Miki, Takashi; Matsuo, Masafumi; Fukuyo, Masaki; Kaneda, Atsushi; Iwama, Atsushi; Nomura, Fumio

    2015-01-01

    FUSE-binding protein (FBP)-interacting repressor (FIR) is a c-myc transcriptional suppressor. A splice variant of FIR that lacks exon 2 in the transcriptional repressor domain (FIRΔexon2) upregulates c-myc transcription by inactivating wild-type FIR. The ratio of FIRΔexon2/FIR mRNA was increased in human colorectal cancer and hepatocellular carcinoma tissues. Because FIRΔexon2 is considered to be a dominant negative regulator of FIR, FIR heterozygous knockout (FIR+/−) C57BL6 mice were generated. FIR complete knockout (FIR−/−) was embryonic lethal before E9.5; therefore, it is essential for embryogenesis. This strongly suggests that insufficiency of FIR is crucial for carcinogenesis. FIR+/− mice exhibited prominent c-myc mRNA upregulation, particularly in the peripheral blood (PB), without any significant pathogenic phenotype. Furthermore, elevated FIRΔexon2/FIR mRNA expression was detected in human leukemia samples and cell lines. Because the single knockout of TP53 generates thymic lymphoma, FIR+/−TP53−/− generated T-cell type acute lymphocytic/lymphoblastic leukemia (T-ALL) with increased organ or bone marrow invasion with poor prognosis. RNA-sequencing analysis of sorted thymic lymphoma cells revealed that the Notch signaling pathway was activated significantly in FIR+/−TP53−/− compared with that in FIR+/+TP53−/− mice. Notch1 mRNA expression in sorted thymic lymphoma cells was confirmed using qRT-PCR. In addition, flow cytometry revealed that c-myc mRNA was negatively correlated with FIR but positively correlated with Notch1 in sorted T-ALL/thymic lymphoma cells. Moreover, the knockdown of TP53 or c-myc using siRNA decreased Notch1 expression in cancer cells. In addition, an adenovirus vector encoding FIRΔexon2 cDNA increased bleomycin-induced DNA damage. Taken together, these data suggest that the altered expression of FIRΔexon2 increased Notch1 at least partially by activating c-Myc via a TP53-independent pathway. In conclusion

  19. Design, synthesis and biological evaluation of 4-anilinoquinazoline derivatives as new c-myc G-quadruplex ligands.

    PubMed

    Jiang, Yin; Chen, Ai-Chun; Kuang, Guo-Tao; Wang, Shi-Ke; Ou, Tian-Miao; Tan, Jia-Heng; Li, Ding; Huang, Zhi-Shu

    2016-10-21

    A series of 4-anilinoquinazoline derivatives were designed and synthesized as novel c-myc promoter G-quadruplex binding ligands. Subsequent biophysical and biochemical evaluation demonstrated that the introduction of aniline group at 4-position of quinazoline ring and two side chains with terminal amino group improved their binding affinity and stabilizing ability to G-quadruplex DNA. RT-PCR assay and Western blot showed that compound 7a could down-regulate transcription and expression of c-myc gene in Hela cells, which was consistent with the behavior of an effective G-quadruplex ligand targeting c-myc oncogene. More importantly, RTCA and colony formation assays indicated that 7a obviously inhibited Hela cells proliferation, without influence on normal primary cultured mouse mesangial cells. Flow cytometric assays suggested that 7a induced Hela cells to arrest in G0/G1 phase both in a time-dependent and dose-dependent manner. PMID:27372288

  20. Intragenic pausing and anti-sense transcription within the murine c-myc locus.

    PubMed Central

    Nepveu, A; Marcu, K B

    1986-01-01

    We present a detailed analysis of strand-specific transcription in different regions of the murine c-myc locus. In normal and transformed cell lines, RNA polymerase II directed transcription occurs in the sense and anti-sense direction. Three noncontiguous regions show a high level of transcription in the anti-sense orientation: upstream of the first exon, within the first intron and in the 3' part of the gene (intron 2 and exon 3). In a cell line carrying a c-myc amplification (54c12), anti-sense transcription is not uniformly increased throughout the locus and is differentially affected by inhibition of protein synthesis. These results suggest that anti-sense transcription in various parts of the locus is independently regulated. In the sense orientation, transcriptional activity is higher in the first exon than in the rest of the gene indicating that transcription pauses near the 3' end of the first exon. The extent of this intragenic pausing varies among different cell lines and is most severe in cells with a c-myc amplification. Transcription initiation and pausing are both negatively regulated by labile proteins. Images Fig. 1. Fig. 2. Fig. 3. Fig. 4. PMID:3024965

  1. CUDR promotes liver cancer stem cell growth through upregulating TERT and C-Myc

    PubMed Central

    Pu, Hu; Zheng, Qidi; Li, Haiyan; Wu, Mengying; An, Jiahui; Gui, Xin; Li, Tianming; Lu, Dongdong

    2015-01-01

    Cancer up-regulated drug resistant (CUDR) is a novel non-coding RNA gene. Herein, we demonstrate excessive CUDR cooperates with excessive CyclinD1 or PTEN depletion to accelerate liver cancer stem cells growth and liver stem cell malignant transformation in vitro and in vivo. Mechanistically, we reveal the decrease of PTEN in cells may lead to increase binding capacity of CUDR to CyclinD1. Therefore, CUDR-CyclinD1 complex loads onto the long noncoding RNA H19 promoter region that may lead to reduce the DNA methylation on H19 promoter region and then to enhance the H19 expression. Strikingly, the overexpression of H19 increases the binding of TERT to TERC and reduces the interplay between TERT with TERRA, thus enhancing the cell telomerase activity and extending the telomere length. On the other hand, insulator CTCF recruits the CUDR-CyclinD1 complx to form the composite CUDR-CyclinD1-insulator CTCF complex which occupancied on the C-myc gene promoter region, increasing the outcome of oncogene C-myc. Ultimately, excessive TERT and C-myc lead to liver cancer stem cell and hepatocyte-like stem cell malignant proliferation. To understand the novel functions of long noncoding RNA CUDR will help in the development of new liver cancer therapeutic and diagnostic approaches. PMID:26513297

  2. Mitochondrial Structure, Function and Dynamics Are Temporally Controlled by c-Myc

    PubMed Central

    Graves, J. Anthony; Wang, Yudong; Sims-Lucas, Sunder; Cherok, Edward; Rothermund, Kristi; Branca, Maria F.; Elster, Jennifer; Beer-Stolz, Donna; Van Houten, Bennett; Vockley, Jerry; Prochownik, Edward V.

    2012-01-01

    Although the c-Myc (Myc) oncoprotein controls mitochondrial biogenesis and multiple enzymes involved in oxidative phosphorylation (OXPHOS), the coordination of these events and the mechanistic underpinnings of their regulation remain largely unexplored. We show here that re-expression of Myc in myc−/− fibroblasts is accompanied by a gradual accumulation of mitochondrial biomass and by increases in membrane polarization and mitochondrial fusion. A correction of OXPHOS deficiency is also seen, although structural abnormalities in electron transport chain complexes (ETC) are not entirely normalized. Conversely, the down-regulation of Myc leads to a gradual decrease in mitochondrial mass and a more rapid loss of fusion and membrane potential. Increases in the levels of proteins specifically involved in mitochondrial fission and fusion support the idea that Myc affects mitochondrial mass by influencing both of these processes, albeit favoring the latter. The ETC defects that persist following Myc restoration may represent metabolic adaptations, as mitochondrial function is re-directed away from producing ATP to providing a source of metabolic precursors demanded by the transformed cell. PMID:22629444

  3. c-myc regulation during retinoic acid-induced differentiation of F9 cells is posttranscriptional and associated with growth arrest.

    PubMed Central

    Dean, M; Levine, R A; Campisi, J

    1986-01-01

    We have shown that c-myc mRNA levels decrease more than 20-fold when F9 teratocarcinoma stem cells are induced to arrest growth and terminally differentiate to parietal endoderm after exposure to retinoic acid and cyclic AMP (Campisi et al., Cell 36:241-247, 1984). Here, we demonstrate that although growth arrest and full expression of the differentiated phenotype required about 3 days, c-myc mRNA declined abruptly between 8 and 16 h after the addition of retinoic acid and cyclic AMP. The decline was independent of cyclic AMP. We found little or no change in the level of c-myc transcription during differentiation, although two other genes showed marked transcriptional regulation. Thus, decreased c-myc mRNA is a consequence of very early posttranscriptional regulation directed by retinoic acid. Differentiation was not fundamental to this regulation. We have shown that sodium butyrate blocks expression of the differentiated phenotype if added within 8 h of retinoic acid and cyclic AMP (Levine et al., Dev. Biol. 105:443-450, 1984). However, butyrate did not inhibit the decrease in c-myc mRNA. Furthermore, F9 cells partially arrested growth without differentiating when grown in isoleucine-deficient medium. Under these conditions, c-myc mRNA levels also declined. Our results suggest that induction of differentiation-specific genes may be under retinoic acid-mediated control dissimilar from that responsible for the decay of c-myc mRNA. In addition, they raise the possibility that growth arrest may be initiated by reduced c-myc expression. Images PMID:3785153

  4. Direct inhibition of c-Myc-Max heterodimers by celastrol and celastrol-inspired triterpenoids

    PubMed Central

    Wang, Huabo; Teriete, Peter; Hu, Angela; Raveendra-Panickar, Dhanya; Pendelton, Kelsey; Lazo, John S.; Eiseman, Julie; Holien, Toril; Misund, Kristine; Oliynyk, Ganna; Arsenian-Henriksson, Marie; Cosford, Nicholas D. P; Sundan, Anders; Prochownik, Edward V.

    2015-01-01

    Many oncogenic signals originate from abnormal protein-protein interactions that are potential targets for small molecule inhibitors. However, the therapeutic disruption of these interactions has proved elusive. We report here that the naturally-occurring triterpenoid celastrol is an inhibitor of the c-Myc (Myc) oncoprotein, which is over-expressed in many human cancers. Most Myc inhibitors prevent the association between Myc and its obligate heterodimerization partner Max via their respective bHLH-ZIP domains. In contrast, we show that celastrol binds to and alters the quaternary structure of the pre-formed dimer and abrogates its DNA binding. Celastrol contains a reactive quinone methide group that promiscuously forms Michael adducts with numerous target proteins and other free sulfhydryl-containing molecules. Interestingly, triterpenoid derivatives lacking the quinone methide showed enhanced specificity and potency against Myc. As with other Myc inhibitors, these analogs rapidly reduced the abundance of Myc protein and provoked a global energy crisis marked by ATP depletion, neutral lipid accumulation, AMP-activated protein kinase activation, cell cycle arrest and apoptosis. They also inhibited the proliferation of numerous established human cancer cell lines as well as primary myeloma explants that were otherwise resistant to JQ1, a potent indirect Myc inhibitor. N-Myc amplified neuroblastoma cells showed similar responses and, in additional, underwent neuronal differentiation. These studies indicate that certain pharmacologically undesirable properties of celastrol such as Michael adduct formation can be eliminated while increasing selectivity and potency toward Myc and N-Myc. This, together with their low in vivo toxicity, provides a strong rationale for pursuing the development of additional Myc-specific triterpenoid derivatives. PMID:26474287

  5. The class-specific BCR tonic signal modulates lymphomagenesis in a c-myc deregulation transgenic model

    PubMed Central

    Amin, Rada; Marfak, Abdelghafour; Pangault, Céline; Oblet, Christelle; Chanut, Aurélie; Tarte, Karin; Denizot, Yves; Cogné, Michel

    2014-01-01

    Deregulation of c-myc by translocation onto immunoglobulin (Ig) loci can promote B cell malignant proliferations with phenotypes as diverse as acute lymphoid leukemia, Burkitt lymphoma, diffuse large B cell lymphoma, myeloma… The B cell receptor (BCR) normally providing tonic signals for cell survival and mitogenic responses to antigens, can also contribute to lymphomagenesis upon sustained ligand binding or activating mutations. BCR signaling varies among cell compartments and BCR classes. For unknown reasons, some malignancies associate with expression of either IgM or class-switched Ig. We explored whether an IgA BCR, with strong tonic signaling, would affect lymphomagenesis in c-myc IgH 3′RR transgenic mice prone to lymphoproliferations. Breeding c-myc transgenics in a background where IgM expression was replaced with IgA delayed lymphomagenesis. By comparison to single c-myc transgenics, lymphomas from double mutant animals were more differentiated and less aggressive, with an altered transcriptional program. Larger tumor cells more often expressed CD43 and CD138, which culminated in a plasma cell phenotype in 10% of cases. BCR class-specific signals thus appear to modulate lymphomagenesis and may partly explain the observed association of specific Ig classes with human B cell malignancies of differential phenotype, progression and prognosis. PMID:25229630

  6. XPC Promotes Pluripotency of Human Dental Pulp Cells through Regulation of Oct-4/Sox2/c-Myc

    PubMed Central

    Liu, Lu; Peng, Zhengjun; Xu, Zhezhen; Wei, Xi

    2016-01-01

    Introduction. Xeroderma pigmentosum group C (XPC), essential component of multisubunit stem cell coactivator complex (SCC), functions as the critical factor modulating pluripotency and genome integrity through interaction with Oct-4/Sox2. However, its specific role in regulating pluripotency and multilineage differentiation of human dental pulp cells (DPCs) remains unknown. Methods. To elucidate the functional role XPC played in pluripotency and multilineage differentiation of DPCs, expressions of XPC in DPCs with long-term culture were examined by real-time PCR and western blot. DPCs were transfected with lentiviral-mediated human XPC gene; then transfection rate was investigated by real-time PCR and western blot. Cell cycle, apoptosis, proliferation, senescence, multilineage differentiation, and expression of Oct-4/Sox2/c-Myc in transfected DPCs were examined. Results. XPC, Oct-4, Sox2, and c-Myc were downregulated at P7 compared with P3 in DPCs with long-term culture. XPC genes were upregulated in DPCs at P2 after transfection and maintained high expression level at P3 and P7. Cell proliferation, PI value, and telomerase activity were enhanced, whereas apoptosis was suppressed in transfected DPCs. Oct-4/Sox2/c-Myc were significantly upregulated, and multilineage differentiation in DPCs with XPC overexpression was enhanced after transfection. Conclusions. XPC plays an essential role in the modulation of pluripotency and multilineage differentiation of DPCs through regulation of Oct-4/Sox2/c-Myc. PMID:27127517

  7. XPC Promotes Pluripotency of Human Dental Pulp Cells through Regulation of Oct-4/Sox2/c-Myc.

    PubMed

    Liu, Lu; Peng, Zhengjun; Xu, Zhezhen; Wei, Xi

    2016-01-01

    Introduction. Xeroderma pigmentosum group C (XPC), essential component of multisubunit stem cell coactivator complex (SCC), functions as the critical factor modulating pluripotency and genome integrity through interaction with Oct-4/Sox2. However, its specific role in regulating pluripotency and multilineage differentiation of human dental pulp cells (DPCs) remains unknown. Methods. To elucidate the functional role XPC played in pluripotency and multilineage differentiation of DPCs, expressions of XPC in DPCs with long-term culture were examined by real-time PCR and western blot. DPCs were transfected with lentiviral-mediated human XPC gene; then transfection rate was investigated by real-time PCR and western blot. Cell cycle, apoptosis, proliferation, senescence, multilineage differentiation, and expression of Oct-4/Sox2/c-Myc in transfected DPCs were examined. Results. XPC, Oct-4, Sox2, and c-Myc were downregulated at P7 compared with P3 in DPCs with long-term culture. XPC genes were upregulated in DPCs at P2 after transfection and maintained high expression level at P3 and P7. Cell proliferation, PI value, and telomerase activity were enhanced, whereas apoptosis was suppressed in transfected DPCs. Oct-4/Sox2/c-Myc were significantly upregulated, and multilineage differentiation in DPCs with XPC overexpression was enhanced after transfection. Conclusions. XPC plays an essential role in the modulation of pluripotency and multilineage differentiation of DPCs through regulation of Oct-4/Sox2/c-Myc. PMID:27127517

  8. SIRT1 activation by a c-MYC oncogenic network promotes the maintenance and drug resistance of human FLT3-ITD acute myeloid leukemia stem cells.

    PubMed

    Li, Ling; Osdal, Tereza; Ho, Yinwei; Chun, Sookhee; McDonald, Tinisha; Agarwal, Puneet; Lin, Allen; Chu, Su; Qi, Jing; Li, Liang; Hsieh, Yao-Te; Dos Santos, Cedric; Yuan, Hongfeng; Ha, Trung-Quang; Popa, Mihaela; Hovland, Randi; Bruserud, Oystein; Gjertsen, Bjørn Tore; Kuo, Ya-Huei; Chen, Wenyong; Lain, Sonia; McCormack, Emmet; Bhatia, Ravi

    2014-10-01

    The FLT3-ITD mutation is frequently observed in acute myeloid leukemia (AML) and is associated with poor prognosis. In such patients, FLT3 tyrosine kinase inhibitors (TKIs) are only partially effective and do not eliminate the leukemia stem cells (LSCs) that are assumed to be the source of treatment failure. Here, we show that the NAD-dependent SIRT1 deacetylase is selectively overexpressed in primary human FLT3-ITD AML LSCs. This SIRT1 overexpression is related to enhanced expression of the USP22 deubiquitinase induced by c-MYC, leading to reduced SIRT1 ubiquitination and enhanced stability. Inhibition of SIRT1 expression or activity reduced the growth of FLT3-ITD AML LSCs and significantly enhanced TKI-mediated killing of the cells. Therefore, these results identify a c-MYC-related network that enhances SIRT1 protein expression in human FLT3-ITD AML LSCs and contributes to their maintenance. Inhibition of this oncogenic network could be an attractive approach for targeting FLT3-ITD AML LSCs to improve treatment outcomes. PMID:25280219

  9. SIRT1 Activation by a c-MYC Oncogenic Network Promotes the Maintenance and Drug Resistance of Human FLT3-ITD Acute Myeloid Leukemia Stem Cells

    PubMed Central

    Li, Ling; Osdal, Tereza; Ho, Yinwei; Chun, Sookhee; McDonald, Tinisha; Agarwal, Puneet; Lin, Allen; Chu, Su; Qi, Jing; Li, Liang; Hsieh, Yao-Te; Santos, Cedric Dos; Yuan, Hongfeng; Ha, Trung-Quang; Popa, Mihaela; Hovland, Randi; Bruserud, Øystein; Gjertsen, Bjørn Tore; Kuo, Ya-Huei; Chen, Wenyong; Lain, Sonia; McCormack, Emmet; Bhatia, Ravi

    2015-01-01

    SUMMARY The FLT3-ITD mutation is frequently observed in acute myeloid leukemia (AML) and is associated with poor prognosis. In such patients, FLT3 tyrosine kinase inhibitors (TKIs) are only partially effective and do not eliminate the leukemia stem cells (LSCs) that are assumed to be the source of treatment failure. Here, we show that the NAD-dependent SIRT1 de-acetylase is selectively overexpressed in primary human FLT3-ITD AML LSCs. This SIRT1 overexpression is related to enhanced expression of the USP22 deubiquitinase induced by c-MYC, leading to reduced SIRT1 ubiquitination and enhanced stability. Inhibition of SIRT1 expression or activity reduced the growth of FLT3-ITD AML LSCs and significantly enhanced TKI-mediated killing of the cells. Therefore, these results identify a c-MYC-related network that enhances SIRT1 protein expression in human FLT3-ITD AML LSCs and contributes to their maintenance. Inhibition of this oncogenic network could be an attractive approach for targeting FLT3-ITD AML LSCs to improve treatment outcomes. PMID:25280219

  10. c-Myc and AMPK Control Cellular Energy Levels by Cooperatively Regulating Mitochondrial Structure and Function

    PubMed Central

    Edmunds, Lia R.; Sharma, Lokendra; Wang, Huabo; Kang, Audry; d’Souza, Sonia; Lu, Jie; McLaughlin, Michael; Dolezal, James M.; Gao, Xiaoli; Weintraub, Susan T.; Ding, Ying; Zeng, Xuemei; Yates, Nathan; Prochownik, Edward V.

    2015-01-01

    The c-Myc (Myc) oncoprotein and AMP-activated protein kinase (AMPK) regulate glycolysis and oxidative phosphorylation (Oxphos) although often for different purposes. Because Myc over-expression depletes ATP with the resultant activation of AMPK, we explored the potential co-dependency of and cross-talk between these proteins by comparing the consequences of acute Myc induction in ampk+/+ (WT) and ampk-/- (KO) murine embryo fibroblasts (MEFs). KO MEFs showed a higher basal rate of glycolysis than WT MEFs and an appropriate increase in response to activation of a Myc-estrogen receptor (MycER) fusion protein. However, KO MEFs had a diminished ability to increase Oxphos, mitochondrial mass and reactive oxygen species in response to MycER activation. Other differences between WT and KO MEFs, either in the basal state or following MycER induction, included abnormalities in electron transport chain function, levels of TCA cycle-related oxidoreductases and cytoplasmic and mitochondrial redox states. Transcriptional profiling of pathways pertinent to glycolysis, Oxphos and mitochondrial structure and function also uncovered significant differences between WT and KO MEFs and their response to MycER activation. Finally, an unbiased mass-spectrometry (MS)-based survey capable of quantifying ~40% of all mitochondrial proteins, showed about 15% of them to be AMPK- and/or Myc-dependent in their steady state. Significant differences in the activities of the rate-limiting enzymes pyruvate kinase and pyruvate dehydrogenase, which dictate pyruvate and acetyl coenzyme A abundance, were also differentially responsive to Myc and AMPK and could account for some of the differences in basal metabolite levels that were also detected by MS. Thus, Myc and AMPK are highly co-dependent and appear to engage in significant cross-talk across numerous pathways which support metabolic and ATP-generating functions. PMID:26230505

  11. Structurally diverse c-Myc inhibitors share a common mechanism of action involving ATP depletion.

    PubMed

    Wang, Huabo; Sharma, Lokendra; Lu, Jie; Finch, Paul; Fletcher, Steven; Prochownik, Edward V

    2015-06-30

    The c-Myc (Myc) oncoprotein is deregulated in a large proportion of diverse human cancers. Considerable effort has therefore been directed at identifying pharmacologic inhibitors as potential anti-neoplastic agents. Three such groups of small molecule inhibitors have been described. The first is comprised of so-called "direct" inhibitors, which perturb Myc's ability to form productive DNA-binding heterodimers in association with its partner, Max. The second group is comprised of indirect inhibitors, which largely function by targeting the BET-domain protein BRD4 to prevent the proper formation of transcriptional complexes that assemble in response to Myc-Max DNA binding. Thirdly, synthetic lethal inhibitors cause the selective apoptosis of Myc over-expressing either by promoting mitotic catastrophe or altering Myc protein stability. We report here a common mechanism by which all Myc inhibitors, irrespective of class, lead to eventual cellular demise. This involves the depletion of ATP stores due to mitochondrial dysfunction and the eventual down-regulation of Myc protein. The accompanying metabolic de-regulation causes neutral lipid accumulation, cell cycle arrest, and an attempt to rectify the ATP deficit by up-regulating AMP-activated protein kinase (AMPK). These responses are ultimately futile due to the lack of functional Myc to support the requisite anabolic response. Finally, the effects of Myc depletion on ATP levels, cell cycle arrest, differentiation and AMPK activation can be mimicked by pharmacologic inhibition of the mitochondrial electron transport chain without affecting Myc levels. Thus, all Myc inhibitors promote a global energy collapse that appears to underlie many of their phenotypic consequences. PMID:26036281

  12. Self-assembly of c-myc DNA promoted by a single enantiomer ruthenium complex as a potential nuclear targeting gene carrier

    PubMed Central

    Wu, Qiong; Mei, Wenjie; Zheng, Kangdi; Ding, Yang

    2016-01-01

    Gene therapy has long been limited in the clinic, due in part to the lack of safety and efficacy of the gene carrier. Herein, a single enantiomer ruthenium(II) complex, Λ-[Ru(bpy)2(p-BEPIP)](ClO4)2 (Λ-RM0627, bpy = 4,4′-bipyridine, p-BEPIP = 2-(4-phenylacetylenephenyl)imidazole [4,5f][1, 10] phenanthroline), has been synthesized and investigated as a potential gene carrier that targets the nucleus. In this report, it is shown that Λ-RM0627 promotes self-assembly of c-myc DNA to form a nanowire structure. Further studies showed that the nano-assembly of c-myc DNA that induced Λ-RM0627 could be efficiently taken up and enriched in the nuclei of HepG2 cells. After treatment of the nano-assembly of c-myc DNA with Λ-RM0627, over-expression of c-myc in HepG2 cells was observed. In summary, Λ-RM0627 played a key role in the transfer and release of c-myc into cells, which strongly indicates Λ-RM0627 as a potent carrier of c-myc DNA that targets the nucleus of tumor cells. PMID:27381008

  13. Self-assembly of c-myc DNA promoted by a single enantiomer ruthenium complex as a potential nuclear targeting gene carrier.

    PubMed

    Wu, Qiong; Mei, Wenjie; Zheng, Kangdi; Ding, Yang

    2016-01-01

    Gene therapy has long been limited in the clinic, due in part to the lack of safety and efficacy of the gene carrier. Herein, a single enantiomer ruthenium(II) complex, Λ-[Ru(bpy)2(p-BEPIP)](ClO4)2 (Λ-RM0627, bpy = 4,4'-bipyridine, p-BEPIP = 2-(4-phenylacetylenephenyl)imidazole [4,5f][1, 10] phenanthroline), has been synthesized and investigated as a potential gene carrier that targets the nucleus. In this report, it is shown that Λ-RM0627 promotes self-assembly of c-myc DNA to form a nanowire structure. Further studies showed that the nano-assembly of c-myc DNA that induced Λ-RM0627 could be efficiently taken up and enriched in the nuclei of HepG2 cells. After treatment of the nano-assembly of c-myc DNA with Λ-RM0627, over-expression of c-myc in HepG2 cells was observed. In summary, Λ-RM0627 played a key role in the transfer and release of c-myc into cells, which strongly indicates Λ-RM0627 as a potent carrier of c-myc DNA that targets the nucleus of tumor cells. PMID:27381008

  14. C-Myc regulates substrate oxidation patterns during early pressure-overload hypertrophy

    SciTech Connect

    Ledee, Dolena R.; Smith, Lincoln; Kajimoto, Masaki; Bruce, Margaret; Isern, Nancy G.; Xu, Chun; Portman, Michael A.; Olson, Aaron

    2013-11-26

    Pressure overload cardiac hypertrophy alters substrate metabolism. Prior work showed that myocardial inactivation of c-Myc (Myc) attenuated hypertrophy and decreased expression of glycolytic genes after aortic constriction. Accordingly, we hypothesize that Myc regulates substrate preferences for the citric acid cycle during pressure overload hypertrophy from transverse aortic constriction (TAC) and that these metabolic changes impact cardiac function and growth. To test this hypothesis, we subjected FVB mice with cardiac specific, inducible Myc inactivation (MycKO-TAC) and non-transgenic littermates (Cont-TAC) to transverse aortic constriction (n=7/group). A separate group underwent sham surgery (Sham, n=5). After two weeks, function was measured in isolated working hearts along with substrate fractional contributions to the citric acid cycle by using perfusate with 13C labeled mixed fatty acids, lactate, ketones and unlabeled glucose and insulin. Western blots were used to evaluate metabolic enzymes. Cardiac function was similar between groups after TAC although +dP/dT and -dP/dT trended towards improvement in MycKO-TAC versus Cont-TAC. Compared to Sham, Cont-TAC had increased free fatty acid fractional contribution with a concurrent decrease in unlabeled (presumably glucose) contribution. Myc inactivation (MycKO-TAC) inhibited these metabolic changes. Hypertrophy in general increased protein levels of PKM2; however this change was not linked to Myc status. Protein post-translation modification by O-GlcNAc was significantly greater in Cont-TAC versus both Sham and MycKO-TAC. In conclusion, Myc regulates substrate utilization during early pressure overload hypertrophy. Our results show that the metabolic switch during hypertrophy is not necessary to maintain cardiac function, but it may be important mechanism to promote cardiomyocyte growth. Myc also regulates protein O-GlcNAcylation during hypertrophy.

  15. Expression of Recombinant Proteins in the Methylotrophic Yeast Pichia pastoris

    PubMed Central

    Weidner, Maria; Taupp, Marcus; Hallam, Steven J.

    2010-01-01

    Protein expression in the microbial eukaryotic host Pichia pastoris offers the possibility to generate high amounts of recombinant protein in a fast and easy to use expression system. As a single-celled microorganism P. pastoris is easy to manipulate and grows rapidly on inexpensive media at high cell densities. Being a eukaryote, P. pastoris is able to perform many of the post-translational modifications performed by higher eukaryotic cells and the obtained recombinant proteins undergo protein folding, proteolytic processing, disulfide bond formation and glycosylation [1]. As a methylotrophic yeast P. pastoris is capable of metabolizing methanol as its sole carbon source. The strong promoter for alcohol oxidase, AOX1, is tightly regulated and induced by methanol and it is used for the expression of the gene of interest. Accordingly, the expression of the foreign protein can be induced by adding methanol to the growth medium [2; 3]. Another important advantage is the secretion of the recombinant protein into the growth medium, using a signal sequence to target the foreign protein to the secretory pathway of P. pastoris. With only low levels of endogenous protein secreted to the media by the yeast itself and no added proteins to the media, a heterologous protein builds the majority of the total protein in the medium and facilitates following protein purification steps [3; 4]. The vector used here (pPICZαA) contains the AOX1 promoter for tightly regulated, methanol-induced expression of the gene of interest; the α-factor secretion signal for secretion of the recombinant protein, a Zeocin resistance gene for selection in both E. coli and Pichia and a C-terminal peptide containing the c-myc epitope and a polyhistidine (6xHis) tag for detection and purification of a recombinant protein. We also show western blot analysis of the recombinant protein using the specific Anti-myc-HRP antibody recognizing the c-myc epitope on the parent vector. PMID:20186119

  16. Modification of the Tumor Microenvironment in KRAS or c-MYC-Induced Ovarian Cancer-Associated Peritonitis

    PubMed Central

    Kawana, Kei; Adachi, Katsuyuki; Kawata, Akira; Ogishima, Juri; Nakamura, Hiroe; Fujimoto, Asaha; Sato, Masakazu; Inoue, Tomoko; Nishida, Haruka; Furuya, Hitomi; Tomio, Kensuke; Arimoto, Takahide; Koga, Kaori; Wada-Hiraike, Osamu; Oda, Katsutoshi; Nagamatsu, Takeshi; Kiyono, Tohru; Osuga, Yutaka; Fujii, Tomoyuki

    2016-01-01

    The most common properties of oncogenes are cell proliferation and the prevention of apoptosis in malignant cells, which, as a consequence, induce tumor formation and dissemination. However, the effects of oncogenes on the tumor microenvironment (TME) have not yet been examined in detail. The accumulation of ascites accompanied by chronic inflammation and elevated concentrations of VEGF is a hallmark of the progression of ovarian cancer. We herein demonstrated the mechanisms by which oncogenes contribute to modulating the ovarian cancer microenvironment. c-MYC and KRAS were transduced into the mouse ovarian cancer cell line ID8. ID8, ID8-c-MYC, or ID8-KRAS cells were then injected into the peritoneal cavities of C57/BL6 mice and the production of ascites was assessed. ID8-c-MYC and ID8-KRAS both markedly accelerated ovarian cancer progression in vivo, whereas no significant differences were observed in proliferative activity in vitro. ID8-KRAS in particular induced the production of ascites, which accumulated between approximately two to three weeks after the injection, more rapidly than ID8 and ID8-c-MYC (between nine and ten weeks and between six and seven weeks, respectively). VEGF concentrations in ascites significantly increased in c-MYC-induced ovarian cancer, whereas the concentrations of inflammatory cytokines in ascites were significantly high in KRAS-induced ovarian cancer and were accompanied by an increased number of neutrophils in ascites. A cytokine array revealed that KRAS markedly induced the expression of granulocyte macrophage colony-stimulating factor (GM-CSF) in ID8 cells. These results suggest that oncogenes promote cancer progression by modulating the TME in favor of cancer progression. PMID:27483433

  17. Modification of the Tumor Microenvironment in KRAS or c-MYC-Induced Ovarian Cancer-Associated Peritonitis.

    PubMed

    Yoshida, Mitsuyo; Taguchi, Ayumi; Kawana, Kei; Adachi, Katsuyuki; Kawata, Akira; Ogishima, Juri; Nakamura, Hiroe; Fujimoto, Asaha; Sato, Masakazu; Inoue, Tomoko; Nishida, Haruka; Furuya, Hitomi; Tomio, Kensuke; Arimoto, Takahide; Koga, Kaori; Wada-Hiraike, Osamu; Oda, Katsutoshi; Nagamatsu, Takeshi; Kiyono, Tohru; Osuga, Yutaka; Fujii, Tomoyuki

    2016-01-01

    The most common properties of oncogenes are cell proliferation and the prevention of apoptosis in malignant cells, which, as a consequence, induce tumor formation and dissemination. However, the effects of oncogenes on the tumor microenvironment (TME) have not yet been examined in detail. The accumulation of ascites accompanied by chronic inflammation and elevated concentrations of VEGF is a hallmark of the progression of ovarian cancer. We herein demonstrated the mechanisms by which oncogenes contribute to modulating the ovarian cancer microenvironment. c-MYC and KRAS were transduced into the mouse ovarian cancer cell line ID8. ID8, ID8-c-MYC, or ID8-KRAS cells were then injected into the peritoneal cavities of C57/BL6 mice and the production of ascites was assessed. ID8-c-MYC and ID8-KRAS both markedly accelerated ovarian cancer progression in vivo, whereas no significant differences were observed in proliferative activity in vitro. ID8-KRAS in particular induced the production of ascites, which accumulated between approximately two to three weeks after the injection, more rapidly than ID8 and ID8-c-MYC (between nine and ten weeks and between six and seven weeks, respectively). VEGF concentrations in ascites significantly increased in c-MYC-induced ovarian cancer, whereas the concentrations of inflammatory cytokines in ascites were significantly high in KRAS-induced ovarian cancer and were accompanied by an increased number of neutrophils in ascites. A cytokine array revealed that KRAS markedly induced the expression of granulocyte macrophage colony-stimulating factor (GM-CSF) in ID8 cells. These results suggest that oncogenes promote cancer progression by modulating the TME in favor of cancer progression. PMID:27483433

  18. c-Myc Regulates Cyclin D-Cdk4 and -Cdk6 Activity but Affects Cell Cycle Progression at Multiple Independent Points

    PubMed Central

    Mateyak, Maria K.; Obaya, Alvaro J.; Sedivy, John M.

    1999-01-01

    c-myc is a cellular proto-oncogene associated with a variety of human cancers and is strongly implicated in the control of cellular proliferation, programmed cell death, and differentiation. We have previously reported the first isolation of a c-myc-null cell line. Loss of c-Myc causes a profound growth defect manifested by the lengthening of both the G1 and G2 phases of the cell cycle. To gain a clearer understanding of the role of c-Myc in cellular proliferation, we have performed a comprehensive analysis of the components that regulate cell cycle progression. The largest defect observed in c-myc−/− cells is a 12-fold reduction in the activity of cyclin D1-Cdk4 and -Cdk6 complexes during the G0-to-S transition. Downstream events, such as activation of cyclin E-Cdk2 and cyclin A-Cdk2 complexes, are delayed and reduced in magnitude. However, it is clear that c-Myc affects the cell cycle at multiple independent points, because restoration of the Cdk4 and -6 defect does not significantly increase growth rate. In exponentially cycling cells the absence of c-Myc reduces coordinately the activities of all cyclin–cyclin-dependent kinase complexes. An analysis of cyclin-dependent kinase complex regulators revealed increased expression of p27KIP1 and decreased expression of Cdk7 in c-myc−/− cells. We propose that c-Myc functions as a crucial link in the coordinate adjustment of growth rate to environmental conditions. PMID:10373516

  19. Prolactin prevents hepatocellular carcinoma by restricting innate immune activation of c-Myc in mice.

    PubMed

    Hartwell, Hadley J; Petrosky, Keiko Y; Fox, James G; Horseman, Nelson D; Rogers, Arlin B

    2014-08-01

    Women are more resistant to hepatocellular carcinoma (HCC) than men despite equal exposure to major risk factors, such as hepatitis B or C virus infection. Female resistance is hormone-dependent, as evidenced by the sharp increase in HCC incidence in postmenopausal women who do not take hormone replacement therapy. In rodent models sex-dimorphic HCC phenotypes are pituitary-dependent, suggesting that sex hormones act via the gonadal-hypophyseal axis. We found that the estrogen-responsive pituitary hormone prolactin (PRL), signaling through hepatocyte-predominant short-form prolactin receptors (PRLR-S), constrained TNF receptor-associated factor (TRAF)-dependent innate immune responses invoked by IL-1β, TNF-α, and LPS/Toll-like receptor 4 (TLR4), but not TRIF-dependent poly(I:C)/TLR3. PRL ubiquitinated and accelerated poststimulatory decay of a "trafasome" comprised of IRAK1, TRAF6, and MAP3K proteins, abrogating downstream activation of c-Myc-interacting pathways, including PI3K/AKT, mTORC1, p38 MAPK, and NF-κB. Consistent with this finding, we documented exaggerated male liver responses to immune stimuli in mice and humans. Tumor promotion through, but regulation above, the level of c-Myc was demonstrated by sex-independent HCC eruption in Alb-Myc transgenic mice. PRL deficiency accelerated liver carcinogenesis in Prl(-/-) mice of both sexes. Conversely, pharmacologic PRL mobilization using the dopamine D2 receptor antagonist domperidone prevented HCC in tumor-prone C3H/HeN males. Viewed together, our results demonstrate that PRL constrains tumor-promoting liver inflammation by inhibiting MAP3K-dependent activation of c-Myc at the level of the trafasome. PRL-targeted therapy may hold promise for reducing the burden of liver cancer in high-risk men and women. PMID:25049387

  20. Dimerization of FIR Upon FUSE DNA Binding Suggests Mechanism of c-myc Inhibition

    SciTech Connect

    Crichlow,G.; Zhou, H.; Hsiao, H.; Frederick, K.; Debrosse, M.; Yang, Y.; Folta-Stogniew, E.; Chung, H.; Fan, C.; et al

    2008-01-01

    c-myc is essential for cell homeostasis and growth but lethal if improperly regulated. Transcription of this oncogene is governed by the counterbalancing forces of two proteins on TFIIH--the FUSE binding protein (FBP) and the FBP-interacting repressor (FIR). FBP and FIR recognize single-stranded DNA upstream of the P1 promoter, known as FUSE, and influence transcription by oppositely regulating TFIIH at the promoter site. Size exclusion chromatography coupled with light scattering reveals that an FIR dimer binds one molecule of single-stranded DNA. The crystal structure confirms that FIR binds FUSE as a dimer, and only the N-terminal RRM domain participates in nucleic acid recognition. Site-directed mutations of conserved residues in the first RRM domain reduce FIR's affinity for FUSE, while analogous mutations in the second RRM domain either destabilize the protein or have no effect on DNA binding. Oppositely oriented DNA on parallel binding sites of the FIR dimer results in spooling of a single strand of bound DNA, and suggests a mechanism for c-myc transcriptional control.

  1. MUC16-mediated activation of mTOR and c-MYC reprograms pancreatic cancer metabolism

    PubMed Central

    Shukla, Surendra K.; Gunda, Venugopal; Abrego, Jaime; Haridas, Dhanya; Mishra, Anusha; Souchek, Joshua; Chaika, Nina V.; Yu, Fang; Sasson, Aaron R.; Lazenby, Audrey J.; Batra, Surinder K.; Singh, Pankaj K.

    2015-01-01

    MUC16, a transmembrane mucin, facilitates pancreatic adenocarcinoma progression and metastasis. In the current studies, we observed that MUC16 knockdown pancreatic cancer cells exhibit reduced glucose uptake and lactate secretion along with reduced migration and invasion potential, which can be restored by supplementing the culture media with lactate, an end product of aerobic glycolysis. MUC16 knockdown leads to inhibition of mTOR activity and reduced expression of its downstream target c-MYC, a key player in cellular growth, proliferation and metabolism. Ectopic expression of c-MYC in MUC16 knockdown pancreatic cancer cells restores the altered cellular physiology. Our LC-MS/MS based metabolomics studies indicate global metabolic alterations in MUC16 knockdown pancreatic cancer cells, as compared to the controls. Specifically, glycolytic and nucleotide metabolite pools were significantly decreased. We observed similar metabolic alterations that correlated with MUC16 expression in primary tumor tissue specimens from human pancreatic adenocarcinoma cancer patients. Overall, our results demonstrate that MUC16 plays an important role in metabolic reprogramming of pancreatic cancer cells by increasing glycolysis and enhancing motility and invasiveness. PMID:26046375

  2. Pleiotropic derepression of developmentally regulated cellular and viral genes by c-myc protooncogene products in undifferentiated embryonal carcinoma cells.

    PubMed Central

    Onclercq, R; Lavenu, A; Cremisi, C

    1989-01-01

    We show here in mouse embryonal carcinoma (EC) cells that the endo A gene is negatively regulated and shares negative transacting factors with the Py and SV40 viruses. The products of the proto-oncogene c-myc derepress at the transcriptional level the appropriately initiated expression of the endo A gene and activate the Py early promoter in EC stem cells. C-myc products also activate the endo A and the Py early promoters in TDM epithelial cells, and the Py early promoter in 3T6 cells in which the two genes are already expressed or can be expressed. Furthermore we show that the myc exon 1 is essential for activation and that this activation might be mediated by AP1 family factors. Images PMID:2536923

  3. c-myc gene sequences and the phylogeny of bats and other eutherian mammals.

    PubMed

    Miyamoto, M M; Porter, C A; Goodman, M

    2000-09-01

    The complete protein-coding sequences of the c-myc proto-oncogene were determined for five species of four new orders of eutherian (placental) mammals. These newly obtained sequences were aligned to each other and to other available orthologs for the phylogenetic estimation of eutherian interordinal relationships. Several measures of sequence difference and base composition were first calculated to assess the major evolutionary properties of the three codon positions and two protein-coding exons of the gene. On the basis of these calculations, different parsimony, distance, and maximum likelihood approaches were adopted, with the most sophisticated involving the separate, then combined, likelihood analyses of the third codon positions of exon 2 versus all other sites. These phylogenetic approaches provided clear support for the grouping of Chiroptera (bats) with Artiodactyla (ruminants, camels, and pigs) and Carnivora (cats, dogs, and their allies), an interordinal arrangement that receives strong corroboration from other lines of evidence including complete mitochondrial DNA sequences. In contrast, these analyses failed to provide strong to reasonable support for any other interordinal group. This study concludes with specific recommendations about sampling and other strategies for maximizing the phylogenetic contributions of the c-myc gene to the continued resolution of the eutherian ordinal tree. PMID:12116424

  4. Resistance to anticancer drugs in NIH3T3 cells transfected with c-myc and/or c-H-ras genes.

    PubMed Central

    Niimi, S.; Nakagawa, K.; Yokota, J.; Tsunokawa, Y.; Nishio, K.; Terashima, Y.; Shibuya, M.; Terada, M.; Saijo, N.

    1991-01-01

    NIH3T3 cells transfected with c-H-ras and/or c-myc genes were examined for differences in drug sensitivity. The five transfectants used were N8, NIH3T3-nm-1, pT22-3-nm-2, pP1-4 and pT22-3. They were transfected with pKOneo alone, pKOneo and c-myc, pKOneo and c-myc plus activated c-H-ras, normal c-H-ras and activated c-H-ras genes, respectively. The IC50s of cisplatin, 4-hydroperoxycyclophosphamide, adriamycin, melphalan, and CPT-11 were significantly higher for NIH3T3-nm-1 abd pT22-3-nm-2 than for the parental NIH3T3 and N8 cells. Transfection with normal and activated C-H-ras oncogenes only led to increases in the IC50s of alkylating agents. There was no significant difference between the IC50s of N8 and those of NIH3T3 parental cells to any of these anticancer agents. These results strongly suggest that the expression of the c-myc gene plays a role in the acquisition of drug resistance. The c-myc gene may therefore provide us with an important clue in determining the mechanism of drug resistance. Images Figure 1 Figure 2 Figure 3 PMID:1997100

  5. Myc and Omomyc functionally associate with the Protein Arginine Methyltransferase 5 (PRMT5) in glioblastoma cells

    PubMed Central

    Mongiardi, Maria Patrizia; Savino, Mauro; Bartoli, Laura; Beji, Sara; Nanni, Simona; Scagnoli, Fiorella; Falchetti, Maria Laura; Favia, Annarita; Farsetti, Antonella; Levi, Andrea; Nasi, Sergio; Illi, Barbara

    2015-01-01

    The c-Myc protein is dysregulated in many human cancers and its function has not been fully elucitated yet. The c-Myc inhibitor Omomyc displays potent anticancer properties in animal models. It perturbs the c-Myc protein network, impairs c-Myc binding to the E-boxes, retaining transrepressive properties and inducing histone deacetylation. Here we have employed Omomyc to further analyse c-Myc activity at the epigenetic level. We show that both Myc and Omomyc stimulate histone H4 symmetric dimethylation of arginine (R) 3 (H4R3me2s), in human glioblastoma and HEK293T cells. Consistently, both associated with protein Arginine Methyltransferase 5 (PRMT5)—the catalyst of the reaction—and its co-factor Methylosome Protein 50 (MEP50). Confocal experiments showed that Omomyc co-localized with c-Myc, PRMT5 and H4R3me2s-enriched chromatin domains. Finally, interfering with PRMT5 activity impaired target gene activation by Myc whereas it restrained Omomyc-dependent repression. The identification of a histone-modifying complex associated with Omomyc represents the first demonstration of an active role of this miniprotein in modifying chromatin structure and adds new information regarding its action on c-Myc targets. More importantly, the observation that c-Myc may recruit PRMT5-MEP50, inducing H4R3 symmetric di-methylation, suggests previously unpredictable roles for c-Myc in gene expression regulation and new potential targets for therapy. PMID:26563484

  6. Co-overexpression of bcl-2 and c-myc in uterine cervix carcinomas and premalignant lesions.

    PubMed

    Protrka, Z; Arsenijevic, S; Dimitrijevic, A; Mitrovic, S; Stankovic, V; Milosavljevic, M; Kastratovic, T; Djuric, J

    2011-01-01

    To establish the role of co-overexpression of bcl-2 and c-myc protooncogenes in uterine cervix carcinogenesis, we examined 138 tissue samples of low grade cervical squamous intraepithelial lesions (SIL), high grade SIL, portio vaginalis uteri (PVU) carcinoma in situ and PVU carcinoma invasive, stage IA-IIA (study group) and 36 samples without SIL or malignancy (control group). The expression of bcl-2 and c-myc was detected immunohistochemically using a monoclonal antibody. Fisher’s exact test (P<0.05) was used to assess statistical significance. Overexpression of bcl-2 was found to increase in direct relation to the grade of the cervical lesions. High sensitivity was of great diagnostic significance for the detection of these types of changes in the uterine cervix. On the basis of high predictive values it can be said that in patients with bcl-2 overexpression there is a great possibility that they have premalignant or malignant changes in the uterine cervix. Co-overexpression of bcl-2 and c-myc oncogenes was found only in patients with PVU invasive carcinoma (6/26-23.0%). Statistically significant difference was not found in the frequency of co-overexpression in patients with PVU invasive carcinoma in relation to the control group (Fisher’s test; P=0.064). The method's sensitivity of determining these oncogenes with the aim of detecting PVU invasive carcinoma was 23%, while specificity was 72.2%. On the basis of high predictive values (100%), speaking in statistical terms, it can be concluded that all patients with co-overexpression of bcl-2 and c-myc oncogenes will have PVU invasive carcinoma. We confirmed in our research that co-overexpression of bcl-2 and c-myc oncogenes was increased only in PVU invasive carcinoma. However, a more extensive series of samples and additional tests are required to establish the prognostic significance of bcl-2 and c-myc co-overexpression in cervical carcinogenesis. PMID:21556123

  7. The small Rho GTPase Rac1 controls normal human dermal fibroblasts proliferation with phosphorylation of the oncoprotein c-myc

    SciTech Connect

    Nikolova, Ekaterina; Mitev, Vanio; Zhelev, Nikolai; Deroanne, Christophe F. . E-mail: yves.poumay@fundp.ac.be

    2007-08-03

    Proliferation of dermal fibroblasts is crucial for the maintenance of skin. The small Rho GTPase, Rac1, has been identified as a key transducer of proliferative signals in various cell types, but in normal human dermal fibroblasts its significance to cell growth control has not been studied. In this study, we applied the method of RNA interference to suppress endogenous Rac1 expression and examined the consequences on human skin fibroblasts. Rac1 knock-down resulted in inhibition of DNA synthesis. This effect was not mediated by inhibition of the central transducer of proliferative stimuli, ERK1/2 or by activation of the pro-apoptotic p38. Rather, as a consequence of the suppressed Rac1 expression we observed a significant decrease in phosphorylation of c-myc, revealing for the first time that in human fibroblasts Rac1 exerts control on proliferation through c-myc phosphorylation. Thus Rac1 activates proliferation of normal fibroblasts through stimulation of c-myc phosphorylation without affecting ERK1/2 activity.

  8. Redox regulation of cardiomyocyte cell cycling via an ERK1/2 and c-Myc-dependent activation of cyclin D2 transcription

    PubMed Central

    Murray, Thomas V.A.; Smyrnias, Ioannis; Schnelle, Moritz; Mistry, Rajesh K.; Zhang, Min; Beretta, Matteo; Martin, Daniel; Anilkumar, Narayana; de Silva, Shana M.; Shah, Ajay M.; Brewer, Alison C.

    2015-01-01

    Adult mammalian cardiomyocytes have a very limited capacity to proliferate, and consequently the loss of cells after cardiac stress promotes heart failure. Recent evidence suggests that administration of hydrogen peroxide (H2O2), can regulate redox-dependent signalling pathway(s) to promote cardiomyocyte proliferation in vitro, but the potential relevance of such a pathway in vivo has not been tested. We have generated a transgenic (Tg) mouse model in which the H2O2-generating enzyme, NADPH oxidase 4 (Nox4), is overexpressed within the postnatal cardiomyocytes, and observed that the hearts of 1–3 week old Tg mice pups are larger in comparison to wild type (Wt) littermate controls. We demonstrate that the cardiomyocytes of Tg mouse pups have increased cell cycling capacity in vivo as determined by incorporation of 5-bromo-2′-deoxyuridine. Further, microarray analyses of the transcriptome of these Tg mouse hearts suggested that the expression of cyclin D2 is significantly increased. We investigated the molecular mechanisms which underlie this more proliferative phenotype in isolated neonatal rat cardiomyocytes (NRCs) in vitro, and demonstrate that Nox4 overexpression mediates an H2O2-dependent activation of the ERK1/2 signalling pathway, which in turn phosphorylates and activates the transcription factor c-myc. This results in a significant increase in cyclin D2 expression, which we show to be mediated, at least in part, by cis-acting c-myc binding sites within the proximal cyclin D2 promoter. Overexpression of Nox4 in NRCs results in an increase in their proliferative capacity that is ablated by the silencing of cyclin D2. We further demonstrate activation of the ERK1/2 signalling pathway, increased phosphorylation of c-myc and significantly increased expression of cyclin D2 protein in the Nox4 Tg hearts. We suggest that this pathway acts to maintain the proliferative capacity of cardiomyocytes in Nox4 Tg pups in vivo and so delays their exit from the cell

  9. miRNA-29a as a tumor suppressor mediates PRIMA-1Met-induced anti-myeloma activity by targeting c-Myc

    PubMed Central

    Yang, Yijun; Chang, Hong

    2016-01-01

    The proto-oncogene c-Myc plays substantial role in multiple myeloma (MM) pathogenesis and is considered a potential drug target. Here we provide evidence of a novel mechanism for PRIMA-1Met, a small molecule with anti-tumor activity in phase I/II clinical trial, showing that PRIMA-1Met induces apoptosis in MM cells by suppressing c-Myc and upregulating miRNA-29a. Our study further demonstrates that miRNA-29a functions as a tumor suppressor which targets c-Myc. The baseline expression of miR-29a was significantly lower in MM cell lines and MM patient samples compared to normal hematopoietic cells. In addition, ectopic expression of miRNA-29a or exposure to PRIMA-1Met reduced cell proliferation and induced apoptosis in MM cells. On the other hand, overexpression of c-Myc at least partially reverted the inhibitory effects of PRIMA-1Met or miRNA-29a overexpression suggesting the miRNA-29a/c-Myc axis mediates anti-myeloma effects of PRIMA-1Met. Importantly, intratumor delivery of miRNA-29a mimics induced regression of tumors in mouse xenograft model of MM and this effect synergized with PRIMA-1Met. Our study indicates that miRNA-29a is a tumor suppressor that plays an important role during PRIMA-1Met-induced apoptotic signaling by targeting c-Myc and provides the basis for novel therapeutic strategies using miRNA-29a mimics combined with PRIMA-1Met in MM. PMID:26771839

  10. c-MYC Generates Repair Errors via Increased Transcription of Alternative-NHEJ Factors, LIG3 and PARP1, in Tyrosine Kinase-activated Leukemias

    PubMed Central

    Muvarak, Nidal; Kelley, Shannon; Robert, Carine; Baer, Maria R.; Perrotti, Danilo; Gambacorti-Passerini, Carlo; Civin, Curt; Scheibner, Kara; Rassool, Feyruz

    2015-01-01

    Leukemias expressing the constitutively activated tyrosine kinases (TKs) BCR-ABL1 and FLT3/ITD activate signaling pathways that increase genomic instability through generation of reactive oxygen species (ROS), DNA double-strand breaks (DSBs) and error-prone repair. The non-homologous end-joining (NHEJ) pathway is a major pathway for DSB repair and is highly aberrant in TK-activated-leukemias; an alternative form of NHEJ (ALT-NHEJ) predominates, evidenced by increased expression of DNA ligase IIIα (LIG3) and poly (ADP-ribose) polymerase (PARP1), increased frequency of large genomic deletions, and repair using DNA sequence microhomologies. This study, for the first time, demonstrates that the TK target c-MYC plays a role in transcriptional activation and subsequent expression of LIG3 and PARP1 and contributes to the increased error-prone repair observed in TK-activated leukemias. c-MYC negatively regulates microRNAs miR-150 and miR-22 which demonstrate an inverse correlation with LIG3 and PARP1 expression in primary and cultured leukemia cells and chronic myelogenous leukemia (CML) human patient samples. Notably, inhibition of c-MYC and overexpression of miR-150 and -22 decreases ALT-NHEJ activity. Thus, BCR-ABL1 or FLT3/ITD induces c-MYC expression leads to genomic instability via augmented expression of ALT-NHEJ repair factors that generate repair errors. PMID:25828893

  11. Genomic instability in B-cells and diversity of recombinations that activate c-myc.

    PubMed

    Janz, S; Jones, G M; Müller, J R; Potter, M

    1995-01-01

    Genetic rearrangements activating the proto-oncogene c-myc comprise a mandatory oncogenic step in plasma cell tumor development in BALB/cAnPt mice. In the majority of plasmacytomas, c-myc activating rearrangements take the form of reciprocal chromosomal translocations t(12;15) that juxtapose c-myc to the immunoglobulin heavy chain alpha locus (IgH alpha) in particular the switch alpha region (S alpha). The genetic basis for the prevalence of S alpha/c-myc recombinations in BALB/cAnPt plasmacytomas is not known but may be related to a hypothetical regional genomic instability of the c-myc and IgH alpha loci in BALB/cAnPt mice. We wished to test whether the genomic instability of both loci might be revealed by the diversity of genetic recombinations that can be observed in IgH alpha and c-myc. We employed PCR methods to detect new recombinations of c-myc and IgH alpha in the preneoplastic stage of plasma cell tumor development and found that c-myc can be joined to more genes or genomic regions than known before. This is indicative but does not formally prove a particular genomic instability of c-myc and IgH alpha in BALB/cAnPt B cells. Since defective DNA repair provides a mechanistic explanation for genomic instability, we measured the efficiency of repair in IgH alpha and c-myc using an assay that quantitates the removal of UV-induced pyrimidine dimers within specific genomic regions. We used plasmacytoma XRPC 24 as a model system and found that both IgH alpha and c-myc were poorly repaired, whereas c-abl, a proto-oncogene not related to conventional pristane-induced plasmacytoma-genesis, was efficiently repaired. PMID:7895512

  12. Convergence of cMyc and β-catenin on Tcf7l1 enables endoderm specification.

    PubMed

    Morrison, Gillian; Scognamiglio, Roberta; Trumpp, Andreas; Smith, Austin

    2016-02-01

    The molecular machinery that directs formation of definitive endoderm from pluripotent stem cells is not well understood. Wnt/β-catenin and Nodal signalling have been implicated, but the requirements for lineage specification remain incompletely defined. Here, we demonstrate a potent effect of inhibiting glycogen synthase kinase 3 (GSK3) on definitive endoderm production. We find that downstream of GSK3 inhibition, elevated cMyc and β-catenin act in parallel to reduce transcription and DNA binding, respectively, of the transcriptional repressor Tcf7l1. Tcf7l1 represses FoxA2, a pioneer factor for endoderm specification. Deletion of Tcf7l1 is sufficient to allow upregulation of FoxA2 in the presence of Activin. In wild-type cells, cMyc contributes by reducing Tcf7l1 mRNA, while β-catenin acts on Tcf7l1 protein. GSK3 inhibition is further required for consolidation of endodermal fate via upregulation of Sox17, highlighting sequential roles for Wnt signalling. The identification of a cMyc/β-catenin-Tcf7l1-FoxA2 axis reveals a de-repression mechanism underlying endoderm induction that may be recapitulated in other developmental and patho-logical contexts. PMID:26675138

  13. Id2 leaves the chromatin of the E2F4–p130-controlled c-myc promoter during hepatocyte priming for liver regeneration

    PubMed Central

    Rodríguez, José L.; Sandoval, Juan; Serviddio, Gaetano; Sastre, Juan; Morante, María; Perrelli, Maria-Giulia; Martínez-Chantar, María L.; Viña, José; Viña, Juan R.; Mato, José M.; Ávila, Matías A.; Franco, Luis; López-Rodas, Gerardo; Torres, Luis

    2006-01-01

    The Id (inhibitor of DNA binding or inhibitor of differentiation) helix–loop–helix proteins are involved in the regulation of cell growth, differentiation and cancer. The fact that the molecular mechanisms of liver regeneration are not completely understood prompted us to study the fate of Id2 in proliferating liver. Id2 increases in liver regeneration after partial hepatectomy, following the early induction of its gene. Co-immunoprecipitation shows that Id2 forms a complex with E2F4, p130 and mSin3A in quiescent liver and all these components are present at the c-myc promoter as shown using ChIP (chromatin immunoprecipitation). Activation of c-myc during hepatocyte priming (G0–G1 transition) correlates with the dissociation of Id2 and HDAC (histone deacetylase), albeit p130 remains bound at least until 6 h. Moreover, as the G0–G1 transition progresses, Id2 and HDAC again bind the c-myc promoter concomitantly with the repression of this gene. The time course of c-myc binding to the Id2 promoter, as determined by ChIP assays is compatible with a role of the oncoprotein as a transcriptional inducer of Id2 in liver regeneration. Immunohistochemical analysis shows that Id2 also increases in proliferating hepatocytes after bile duct ligation. In this case, the pattern of Id2 presence in the c-myc promoter parallels that found in regenerating liver. Our results may suggest a control role for Id2 in hepatocyte priming, through a p130 dissociation-independent regulation of c-myc. PMID:16776654

  14. Cardiac mesenchymal progenitors differentiate into adipocytes via Klf4 and c-Myc

    PubMed Central

    Kami, D; Kitani, T; Kawasaki, T; Gojo, S

    2016-01-01

    Direct reprogramming of differentiated cells to pluripotent stem cells has great potential to improve our understanding of developmental biology and disorders such as cancers, and has implications for regenerative medicine. In general, the effects of transcription factors (TFs) that are transduced into cells can be influenced by pre-existing transcriptional networks and epigenetic modifications. However, previous work has identified four key TFs, Oct4, Sox2, Klf4 and c-Myc, which can reprogram various differentiated cells to generate induced pluripotent stem cells. Here, we show that in the heart, the transduction of cardiac mesenchymal progenitors (CMPs) with Klf4 and c-Myc (KM) was sufficient to drive the differentiation of these cells into adipocytes without the use of adipogenic stimulation cocktail, that is, insulin, 3-isobutyl-1-methylxanthine (IBMX) and dexamethasone. KM-transduced CMPs exhibited a gradually increased expression of adipogenic-related genes, such as C/Ebpα, Pparγ and Fabp4, activation of the peroxisome proliferator-activated receptor (PPAR) signaling pathway, inactivation of the cell cycle-related pathway and formation of cytoplasmic lipid droplets within 10 days. In contrast, NIH3T3 fibroblasts, 3T3-L1 preadipocytes, and bone marrow-derived mesenchymal stem cells transduced with KM did not differentiate into adipocytes. Both in vitro and in vivo cardiac ischemia reperfusion injury models demonstrated that the expression of KM genes sharply increased following a reperfusion insult. These results suggest that ectopic adipose tissue formation in the heart following myocardial infarction results from CMPs that express KM following a stress response. PMID:27077806

  15. Differential stability of c-myc mRNAS in a cell-free system

    SciTech Connect

    Pei, R.; Calame, K.

    1988-07-01

    The authors have developed a simple cell-free system for studying the stability of different mRNAs in vitro. They demonstrate that the threefold greater stability in vivo of truncated c-myc mRNA (lacking exon 1) compared with that of full-length c-myc mRNA is maintained in our in vitro system. Chimeric mRNAs in which the first exon of c-myc was fused to immunoglobulin C ..cap alpha.. heavy chain of glyceraldehyde-3-phosphate dehydrogenase mRNAs were not rapidly degraded, demonstrating that c-myc exon 1 alone is not sufficient to tag mRNAs for rapid degradation. Competition experiments show that full-length c-myc mRNA is specifically recognized by a factor(s) responsible for its rapid degradation. This system will allow further characterization and purification of these factors.

  16. Combined loss of PUMA and p21 accelerates c-MYC-driven lymphoma development considerably less than loss of one allele of p53.

    PubMed

    Valente, L J; Grabow, S; Vandenberg, C J; Strasser, A; Janic, A

    2016-07-21

    The tumor suppressor p53 is mutated in ~50% of human cancers. P53 is activated by a range of stimuli and regulates several cellular processes, including apoptotic cell death, cell cycle arrest, senescence and DNA repair. P53 induces apoptosis via transcriptional induction of the BH3-only proteins PUMA (p53-upregulated modulator of apoptosis) and NOXA, and cell cycle arrest via p21. Induction of these processes was proposed to be critical for p53-mediated tumor suppression. It is therefore surprising that mice lacking PUMA, NOXA and p21, as well as mice bearing mutations in p53 that impair the transcriptional activation of these genes, are not tumor prone, unlike mice lacking p53 function, which spontaneously develop tumors with 100% incidence. These p53 target genes and the processes they regulate may, however, impact differently on tumor development depending on the oncogenic drivers. For example, loss of PUMA enhances c-MYC-driven lymphoma development in mice, but, interestingly, the acceleration was less impressive compared with that caused by the loss of even a single p53 allele. Different studies have reported that loss of p21 can accelerate, delay or have no impact on tumorigenesis. In an attempt to resolve this controversy, we examined whether loss of p21-mediated cell cycle arrest cooperates with PUMA deficiency in accelerating lymphoma development in Eμ-Myc mice (overexpressing c-MYC in B-lymphoid cells). We found that Eμ-Myc mice lacking both p21 and PUMA (Eμ-Myc;Puma(-/-);p21(-/-)) developed lymphoma at a rate comparable to Eμ-Myc;Puma(-/-) animals, notably with considerably longer latency than Eμ-Myc;p53(+/-)mice. Loss of p21 had no impact on the numbers, cycling or survival of pre-leukemic Eμ-Myc B-lymphoid cells, even when PUMA was lost concomitantly. These results demonstrate that even in the context of deregulated c-MYC expression, p53 must suppress tumor development by activating processes apart from, or in addition to, PUMA

  17. A link between increased transforming activity of lymphoma-derived MYC mutant alleles, their defective regulation by p107, and altered phosphorylation of the c-Myc transactivation domain.

    PubMed Central

    Hoang, A T; Lutterbach, B; Lewis, B C; Yano, T; Chou, T Y; Barrett, J F; Raffeld, M; Hann, S R; Dang, C V

    1995-01-01

    The c-Myc protein is a transcription factor with an N-terminal transcriptional regulatory domain and C-terminal oligomerization and DNA-binding motifs. Previous studies have demonstrated that p107, a protein related to the retinoblastoma protein, binds to the c-Myc transcriptional activation domain and suppresses its activity. We sought to characterize the transforming activity and transcriptional properties of lymphoma-derived mutant MYC alleles. Alleles encoding c-Myc proteins with missense mutations in the transcriptional regulatory domain were more potent than wild-type c-Myc in transforming rodent fibroblasts. Although the mutant c-Myc proteins retained their binding to p107 in in vitro and in vivo assays, p107 failed to suppress their transcriptional activation activities. Many of the lymphoma-derived MYC alleles contain missense mutations that result in substitution for the threonine at codon 58 or affect sequences flanking this amino acid. We observed that in vivo phosphorylation of Thr-58 was absent in a lymphoma cell line with a mutant MYC allele containing a missense mutation flanking codon 58. Our in vitro studies suggest that phosphorylation of Thr-58 in wild-type c-Myc was dependent on cyclin A and required prior phosphorylation of Ser-62 by a p107-cyclin A-CDK complex. In contrast, Thr-58 remained unphosphorylated in two representative mutant c-Myc transactivation domains in vitro. Our studies suggest that missense mutations in MYC may be selected for during lymphomagenesis, because the mutant MYC proteins have altered functional interactions with p107 protein complexes and fail to be phosphorylated at Thr-58. PMID:7623799

  18. c-Myc and Transforming Growth Factor α Enhance the Development of Hepatic Lesions Due to Mutant β-Catenin in Transgenic Mice

    PubMed Central

    Jochem, Adam S; Holmes, Katie E; Stein, Timothy J

    2014-01-01

    Alterations in the Wnt signaling pathway are associated with diverse cancers, including hepatocellular carcinoma (HCC). The development of HCC is thought to be a multistage process in which multiple genetic alterations are necessary. Few studies have assessed the effect of aberrant Wnt signaling activity in association with other molecular alterations in HCC. Here we sought to determine whether co-overexpression of c-Myc or TGFα, 2 signaling molecules known to contribute to HCC development, enhanced the development of hepatic lesions associated with a stabilized β-catenin. The coexpression of mutant β-catenin with either c-Myc or TGFα within hepatocytes increased the severity of hepatic lesions compared with that associated with any of the transgenes expressed individually. The coexpression of mutant β-catenin with c-Myc or TGFα resulted in severe hepatomegaly necessitating the euthanasia of mice by an average of 156 and 128 d, respectively, after the cessation of doxycycline. The expression of mutant β-catenin alone resulted in mild to moderate hepatomegaly that prompted the euthanasia of mice by an average of 75 d after the cessation of doxycycline. Collectively, these findings indicate that coexpression of c-Myc or TGFα delays the onset of endstage hepatic disease yet enhances the severity of hepatic lesions due to mutant β-catenin. PMID:25402175

  19. Induction of the c-myc protooncogene following antigen binding to hapten-specific B cells

    SciTech Connect

    Snow, E.C.; Fetherston, J.; Zimmer, S.

    1986-03-01

    Considerable controversy has centered on the role that the surface immunoglobulin (sIg) receptor for antigen plays during the induction of B cell activation. Stimulation by anti-Ig reagents has been shown to activate G/sub 0/ B cells to enter the cell cycle. The binding of thymus-dependent antigens to hapten-specific B cell populations apparently does not result in the movement of the antigen-binding cells (ABC) into the G/sub 1/ stage of the cell cycle. However, the authors have recently demonstrated that antigen binding to such hapten-specific B cells does result in the initiation of the membrane phosphatidylinositol cycle. In the present experiments, hapten-specific B cells (80-90% ABC, 99% in G/sub 0/) were incubated with either the correct hapten-carrier conjugate, with the carrier protein, or only media for 2 hours at 37/sup 0/C. At that time, total cellular RNA was isolated and subsequently analyzed by either dot blots or Northern gel techniques. The blots were probed with a (/sup 32/P)-c-myc SstI-Xhol fragment. The results indicate that hapten carrier stimulation of the hapten-specific B cells induces enhanced transcription of the c-myc gene. These observations lend further support to the premise that antigen binding to the sIg receptor results in the transduction to the cell of important signals and implicates the active participation of sIg during the process of antigen-mediated B cell activation.

  20. microRNA-206 impairs c-Myc-driven cancer in a synthetic lethal manner by directly inhibiting MAP3K13

    PubMed Central

    Han, Han; Chen, Yuxing; Cheng, Li; Prochownik, Edward V.; Li, Youjun

    2016-01-01

    c-Myc (Myc) is one of the most frequently dysregulated oncogenic transcription factors in human cancer. By functionally screening a microRNA (miR) library, we identified miR-206 as being a synthetic lethal in Myc over-expressing human cancer cells. miR-206 inhibited MAP3K13, which resulted in Myc protein de-stabilization, and an inhibition of anchorage-independent growth and in vivo tumorigenesis by Myc over-expressing human cancer cells. Eliminating MAP3K13 by shRNA recapitulated the effects caused by miR-206, thus supporting the idea that miR-206's effect on Myc was mediated through MAP3K13. Conversely, enforced expression of MAP3K13 stabilized Myc by promoting its N-terminal phosphorylation and enhancing its transcriptional activity. Gene expression analyses of breast cancers expressing high levels of Myc indicated that low miR-206 expression and high MAP3K13 expression correlated with poor patient survival. The critical link between miR-206 and MAP3K13 in the development of Myc over-expressing human cancers suggests potential points of therapeutic intervention for this molecular sub-category. PMID:26918941

  1. Growth inhibition and apoptosis induced by daunomycin-conjugated triplex-forming oligonucleotides targeting the c-myc gene in prostate cancer cells

    PubMed Central

    Napoli, Sara; Negri, Umberto; Arcamone, Federico; Capobianco, Massimo L.; Carbone, Giuseppina M.; Catapano, Carlo V.

    2006-01-01

    Covalent attachment of intercalating agents to triplex-forming oligonucleotides (TFOs) is a promising strategy to enhance triplex stability and biological activity. We have explored the possibility to use the anticancer drug daunomycin as triplex stabilizing agent. Daunomycin-conjugated TFOs (dauno-TFOs) bind with high affinity and maintain the sequence-specificity required for targeting individual genes in the human genome. Here, we examined the effects of two dauno-TFOs targeting the c-myc gene on gene expression, cell proliferation and survival. The dauno-TFOs were directed to sequences immediately upstream (dauno-GT11A) and downstream (dauno-GT11B) the major transcriptional start site in the c-myc gene. Both dauno-TFOs were able to down-regulate promoter activity and transcription of the endogenous gene. Myc-targeted dauno-TFOs inhibited growth and induced apoptosis of prostate cancer cells constitutively expressing the gene. Daunomycin-conjugated control oligonucleotides with similar sequences had only minimal effects, confirming that the activity of dauno-TFOs was sequence-specific and triplex-mediated. To test the selectivity of dauno-TFOs, we examined their effects on growth of normal human fibroblasts, which express low levels of c-myc. Despite their ability to inhibit c-myc transcription, both dauno-TFOs failed to inhibit growth of normal fibroblasts at concentrations that inhibited growth of prostate cancer cells. In contrast, daunomycin inhibited equally fibroblasts and prostate cancer cells. Thus, daunomycin per se did not contribute to the antiproliferative activity of dauno-TFOs, although it greatly enhanced their ability to form stable triplexes at the target sites and down-regulate c-myc. Our data indicate that dauno-TFOs are attractive gene-targeting agents for development of new cancer therapeutics. PMID:16449206

  2. Suppression of RAD21 Induces Senescence of MDA-MB-231 Human Breast Cancer Cells Through RB1 Pathway Activation Via c-Myc Downregulation.

    PubMed

    Zhu, Shan; Zhao, Li; Li, Yueyang; Hou, Pingfu; Yao, Ruosi; Tan, Jiang; Liu, Dongxu; Han, Liping; Huang, Baiqu; Lu, Jun; Zhang, Yu

    2016-06-01

    Cellular senescence impedes cancer progression by limiting uncontrolled cell proliferation. To identify new genetic events controlling senescence, we performed a small interfering RNA screening human cancer cells and identified a number of targets potentially involved in senescence of MDA-MB-231 human breast cancer cells. Importantly, we showed that knockdown of RAD21 resulted in the appearance of several senescent markers, including enhanced senescence-associated β-galactosidase activity and heterochromatin focus formation, as well as elevated p21 protein levels and RB1 pathway activation. Further biochemical analyses revealed that RAD21 knockdown led to the downregulation of c-Myc and its targets, including CDK4, a negative regulator of RB1, and blockedRB1 phosphorylation (pRB1), and the RB1-mediated transcriptional repression of E2F. Moreover, c-Myc downregulation was partially mediated by proteasome-dependent degradation within promyelocytic leukemia (PML) nuclear bodies, which were found to be highly abundant during RAD21 knockdown-induced senescence. Exogenous c-Myc reconstitution rescued cells from RAD21 silencing-induced senescence. Altogether, data arising from this study implicate a novel function of RAD21 in cellular senescence in MDA-MB-231 cells that is mainly dependent onRB1 pathway activation via c-Myc downregulation. J. Cell. Biochem. 117: 1359-1369, 2016. © 2015 Wiley Periodicals, Inc. PMID:26529363

  3. Variant (6;15) translocations in murine plasmacytomas involve a chromosome 15 locus at least 72 kb from the c-myc oncogene.

    PubMed Central

    Cory, S; Graham, M; Webb, E; Corcoran, L; Adams, J M

    1985-01-01

    The variant (6;15) translocations in murine plasmacytomas join the myc oncogene-bearing band of chromosome 15 and the immunoglobulin kappa band of chromosome 6. We recently cloned a region from chromosome 15 linked to C kappa and have now used probes from that region to define the major locus of plasmacytoma variant translocations, which we denote pvt-1. In five of nine plasmacytomas we analysed, the 6;15 translocation resulted from reciprocal recombination between the C kappa locus and a 4.5-kb region of pvt-1. Moreover, nearby we located the region shown by others to have undergone a complex (15;12;6) translocation in plasmacytoma PC7183. All the chromosome 6 breakpoints fell between 1 and 3 kb 5' to C kappa but only two were near J kappa genes. Thus the J kappa -C kappa region appears to be a recombination 'hot spot' in lymphocytes, but the breaks are unlikely to be mediated via V/J recombination enzymes. Comparison of a cloned 108-kb region across pvt-1 and another of 52 kb across c-myc established that the pvt-1 breakpoints lie at least 72 kb from the c-myc promoters. Since c-myc is expressed at a substantial level, the 6;15 translocation apparently activates c-myc. Activation may occur directly, at a remarkable distance along the chromosome, or indirectly, via a putative pvt-1 gene product. Images Fig. 3. Fig. 5. PMID:3924592

  4. DOT1L cooperates with the c-Myc-p300 complex to epigenetically derepress CDH1 transcription factors in breast cancer progression

    PubMed Central

    Cho, Min-Hyung; Park, Ji-Hye; Choi, Hee-Joo; Park, Mi-Kyung; Won, Hee-Young; Park, Yeon-Ji; Lee, Chang Hoon; Oh, Seung-Hyun; Song, Young-Soo; Kim, Hyun Sung; Oh, Young-Ha; Lee, Jeong-Yeon; Kong, Gu

    2015-01-01

    DOT1L has emerged as an anticancer target for MLL-associated leukaemias; however, its functional role in solid tumours is largely unknown. Here we identify that DOT1L cooperates with c-Myc and p300 acetyltransferase to epigenetically activate epithelial–mesenchymal transition (EMT) regulators in breast cancer progression. DOT1L recognizes SNAIL, ZEB1 and ZEB2 promoters via interacting with the c-Myc-p300 complex and facilitates lysine-79 methylation and acetylation towards histone H3, leading to the dissociation of HDAC1 and DNMT1 in the regions. The upregulation of these EMT regulators by the DOT1L-c-Myc-p300 complex enhances EMT-induced breast cancer stem cell (CSC)-like properties. Furthermore, in vivo orthotopic xenograft models show that DOT1L is required for malignant transformation of breast epithelial cells and breast tumour initiation and metastasis. Clinically, DOT1L expression is associated with poorer survival and aggressiveness of breast cancers. Collectively, we suggest that cooperative effect of DOT1L and c-Myc-p300 is critical for acquisition of aggressive phenotype of breast cancer by promoting EMT/CSC. PMID:26199140

  5. Quantum dots (QDs) restrain human cervical carcinoma HeLa cell proliferation through inhibition of the ROCK-c-Myc signaling.

    PubMed

    Chen, Liqun; Qu, Guangbo; Zhang, Changwen; Zhang, Shuping; He, Jiuyang; Sang, Nan; Liu, Sijin

    2013-03-01

    Cancers often cause significant morbidity and even death to patients. To date, conventional therapies, such as chemotherapy, radiation and surgery, are often limited; meanwhile, novel anticancer therapeutics are urgently needed to improve clinical treatments. Rapid application of nanotechnology and nanomaterials represents a promising vista for the development of anti-cancer therapeutics. However, how to integrate the novel properties of nanotechnology and nanomaterials into cancer treatment warrants close investigation. In the current study, we report a novel finding about the inhibitory effect of CdSe quantum dots (QDs) on Rho-associated kinase (ROCK) activity in cervical carcinoma HeLa cells associated with the attenuation of the ROCK-c-Myc signaling. We mechanistically demonstrated that QD-conducted ROCK inhibition greatly diminished c-Myc protein stability due to reduced phosphorylation, and also suppressed its activity in transcribing target genes (e.g. HSPC111). Thus, the treatment of QDs greatly restrained HeLa cell growth by inducing cell cycle arrest at G1 phase due to the reduced ability of c-Myc in driving cell proliferation. Additionally, since HSPC111, one of the c-Myc targets, is involved in regulating cell growth through ribosomal biogenesis and assembly, the downregulation of HSPC111 could also contribute to diminished proliferation in HeLa cells upon QD treatment. These results together suggested that inhibition of ROCK activity or ROCK-mediated c-Myc signaling in tumor cells upon QD treatment might represent a promising strategy to restrain tumor progression for human cervical carcinoma. PMID:23370637

  6. The functional basis of c-myc and bcl-2 complementation during multistep lymphomagenesis in vivo.

    PubMed

    Marin, M C; Hsu, B; Stephens, L C; Brisbay, S; McDonnell, T J

    1995-04-01

    Oncogenes are known to be deregulated by chromosomal translocations occurring at high frequency in specific malignancies. Among the most well characterized of these are c-myc, associated with the t(8;14) in Burkitt's lymphomas, and bcl-2, associated with the t(14;18) in follicular lymphomas. In addition to their role in regulating rates of proliferation, it is known that oncogenes and tumor suppressor genes can also regulate rates of apoptotic cell death. The contribution of c-myc and bcl-2 to the regulation of cell death during lymphomagenesis in vivo is assessed using bcl-2-Ig and emu-myc trangenic mice and bcl-2/myc hybrid transgenic mice. Translocations between the endogenous c-myc gene and immunoglobulin loci, e.g., t(12;15), are common in lymphomas arising in the bcl-2-Ig mice. Furthermore, bcl-2/c-myc double transgenic mice exhibit accelerated lymphomagenesis, indicating cooperation between these two oncogenes. Genetic complementation of c-myc and bcl-2 during lymphomagenesis resulted from the suppression of c-myc-associated apoptosis. Other genes are likely involved in regulating cell death during multistep lymphomagenesis. PMID:7698223

  7. Migration of cells with immunoglobulin/c-myc recombinations in lymphoid tissues of mice.

    PubMed

    Müller, J R; Jones, G M; Janz, S; Potter, M

    1997-01-01

    Recombinations between c-myc and immunoglobulin (Ig) sequences that typically occur in pristane-induced mouse plasmacytomas were detected in secondary lymphoid tissues from normal mice, chiefly in the gut-associated lymphoid tissue. Based on the analysis of recombination sequences as clonotypic markers, migration of c-myc recombination-positive cells was observed between Peyer's patches and into the intestine. Treatment of plasmacytoma-susceptible BALB/cAn mice with pristane induced proliferation and migration of these cells into mesenteric lymph node, spleen, and oil granuloma within 7 days. Plasmacytoma-resistant strains of mice (DBA/2N, C3H/HeJ, C57BL/6) differed in that (1) they harbored fewer clones (Ig/c-myc recombinations were detected in 33% of resistant mice versus 91% of BALB/cAn mice after pristane treatment); (2) Ig/c-myc-positive cells were rarely detected in the oil granuloma, and (3) c-myc recombined predominantly with the Ig alpha locus in BALB/cAn mice (72%), but with the Ig mu locus in DBA/2N and in C57BL/6 (67%). The results demonstrate that normal mice generate a large number of lymphocytes with aberrant c-myc in intestinal tissues without developing tumors. PMID:8978304

  8. RNAi delivery by exosome-mimetic nanovesicles - Implications for targeting c-Myc in cancer.

    PubMed

    Lunavat, Taral R; Jang, Su Chul; Nilsson, Lisa; Park, Hyun Taek; Repiska, Gabriela; Lässer, Cecilia; Nilsson, Jonas A; Gho, Yong Song; Lötvall, Jan

    2016-09-01

    To develop RNA-based therapeutics, it is crucial to create delivery vectors that transport the RNA molecule into the cell cytoplasm. Naturally released exosomes vesicles (also called "Extracellular Vesicles") have been proposed as possible RNAi carriers, but their yield is relatively small in any cell culture system. We have previously generated exosome-mimetic nanovesicles (NV) by serial extrusions of cells through nano-sized filters, which results in 100-times higher yield of extracellular vesicles. We here test 1) whether NV can be loaded with siRNA exogenously and endogenously, 2) whether the siRNA-loaded NV are taken up by recipient cells, and 3) whether the siRNA can induce functional knock-down responses in recipient cells. A siRNA against GFP was first loaded into NV by electroporation, or a c-Myc shRNA was expressed inside of the cells. The NV were efficiently loaded with siRNA with both techniques, were taken up by recipient cells, which resulted in attenuation of target gene expression. In conclusion, our study suggests that exosome-mimetic nanovesicles can be a platform for RNAi delivery to cell cytoplasm. PMID:27344366

  9. Chromosomal translocations deregulating c-myc are associated with normal immune responses.

    PubMed

    Roschke, V; Kopantzev, E; Dertzbaugh, M; Rudikoff, S

    1997-06-26

    Plasmacytomas induced in BALB/c mice by pristane consistently evidence chromosomal translocations involving the c-myc gene and one of the Ig loci. This observation has lead to the suggestion that c-myc deregulation is a critical event in the generation of such tumors. However, it is not clear whether c-myc translocation is related to pristane treatment or occurs in normal lymphocyte populations nor whether such translocations occur normally, and at similar frequencies, in strains genetically resistant to plasmacytoma development, such as DBA/2. In order to address these questions, a Long Distance PCR assay with single copy sensitivity was employed to assess the frequency of c-myc/IgA translocations in normal and immunized mice of both plasmacytoma resistant and susceptible lineages in the absence of pristane treatment. Our data demonstrate that spontaneous translocations occur in normal DBA/2 and BALB/c mice with no significant differences in frequency. A 3-5-fold increase in translocation frequency was observed in mice immunized with cholera toxin, a strong stimulator of IgA responses. We conclude that c-myc deregulation by chromosomal translocation is associated with normal physiological processes of B-cell differentiation and, as such, can not be the determining factor leading to malignancy. PMID:9223664

  10. RNA Interference Using c-Myc-Conjugated Nanoparticles Suppresses Breast and Colorectal Cancer Models.

    PubMed

    Tangudu, Naveen K; Verma, Vinod K; Clemons, Tristan D; Beevi, Syed S; Hay, Trevor; Mahidhara, Ganesh; Raja, Meera; Nair, Rekha A; Alexander, Liza E; Patel, Anant B; Jose, Jedy; Smith, Nicole M; Zdyrko, Bogdan; Bourdoncle, Anne; Luzinov, Igor; Iyer, K Swaminathan; Clarke, Alan R; Dinesh Kumar, Lekha

    2015-05-01

    In this article, we report the development and preclinical validation of combinatorial therapy for treatment of cancers using RNA interference (RNAi). RNAi technology is an attractive approach to silence genes responsible for disease onset and progression. Currently, the critical challenge facing the clinical success of RNAi technology is in the difficulty of delivery of RNAi inducers, due to low transfection efficiency, difficulties of integration into host DNA and unstable expression. Using the macromolecule polyglycidal methacrylate (PGMA) as a platform to graft multiple polyethyleneimine (PEI) chains, we demonstrate effective delivery of small oligos (anti-miRs and mimics) and larger DNAs (encoding shRNAs) in a wide variety of cancer cell lines by successful silencing/activation of their respective target genes. Furthermore, the effectiveness of this therapy was validated for in vivo tumor suppression using two transgenic mouse models; first, tumor growth arrest and increased animal survival was seen in mice bearing Brca2/p53-mutant mammary tumors following daily intratumoral treatment with nanoparticles conjugated to c-Myc shRNA. Second, oral delivery of the conjugate to an Apc-deficient crypt progenitor colon cancer model increased animal survival and returned intestinal tissue to a non-wnt-deregulated state. This study demonstrates, through careful design of nonviral nanoparticles and appropriate selection of therapeutic gene targets, that RNAi technology can be made an affordable and amenable therapy for cancer. PMID:25695957

  11. Control of c-fos and c-myc proto-oncogene induction in rat thyroid cells in culture

    SciTech Connect

    Isozaki, O.; Kohn, L.D. )

    1987-11-01

    Removal of TSH, insulin, and cortisol from the medium, and decreasing the serum content to 0.2%, abolishes both the proliferate and differentiated state of FRTL-5 rat thyroid cells in culture. In these basal conditions, the individual addition of TSH, insulin, insulin-like growth factor-I (IGF-I), phorbol 12-myristate 13-acetate (TPA), alpha 1-adrenergic agents, or A23187, increase c-myc and/or c-fos proto-oncogene expression. Under the same conditions, only the addition of TSH increased cAMP levels; 8-bromo-cAMP can increase c-myc or c-fos mRNA levels. Pretreatment of cells with phorbol 12,13-dibutyrate, an agent which down regulates the C-kinase, completely inhibits the effect of TPA on proto-oncogene expression but has no affect on the A23187 induced-increase. The sum of these results indicate that at least four separate signal systems independently increase c-myc or c-fos gene expression in FRTL-5 cells cAMP (TSH), C-kinase (TPA), Ca++/phosphoinositide (A23187), and that influenced by insulin/IGF-I. None of the ligands, when individually returned to cells in basal medium (no TSH, insulin, or cortisol and only 0.2% serum), increases cell number; norepinephrine, and A23187 do not increase (3H)thymidine incorporation into DNA under these conditions; and combinations of the ligands can be more than additive in effecting (3H)thymidine incorporation into DNA but are only additive in effecting proto-oncogene expression. Insulin/IGF-I plus TSH or insulin/IGF-I plus norepinephrine can increase both proto-oncogene expression and (3H)thymidine incorporation into DNA to the same extent; however, the former combination can increase cell number whereas the latter cannot. There is therefore no simple correlation between the ability of the above ligands to increase proto-oncogene expression and their ability to increase cell number or induce DNA synthesis.

  12. A Comparative Docking Strategy to Identify Polyphenolic Derivatives as Promising Antineoplastic Binders of G-quadruplex DNA c-myc and bcl-2 Sequences.

    PubMed

    Costa, Giosuè; Rocca, Roberta; Moraca, Federica; Talarico, Carmine; Romeo, Isabella; Ortuso, Francesco; Alcaro, Stefano; Artese, Anna

    2016-09-01

    Polyphenols are compounds ubiquitously expressed in plants and used for their multiple healthy effects in humans as anti-inflammatory, antimicrobial, antiviral, anticancer and immunomodulatory agents. Due to their ability to modulate the activity of multiple targets involved in carcinogenesis, polyphenols can be employed to inhibit the growth of cancer cells. Several studies reported their high affinity to different G-quadruplex DNA structures, including the oncogene promoters c-myc and bcl-2. In this work we applied a structure-based virtual screening approach in order to screen a database of polyphenolic derivatives and human metabolites against both c-myc and bcl-2 DNA G-quadruplex structures. A Delphinidine derivative was identified as the best "dual" candidate and, after molecular dynamics simulations, resulted able to well stabilize both receptors. PMID:27546043

  13. A strategy for combating melanoma with oncogenic c-Myc inhibitors and targeted nanotherapy

    PubMed Central

    Pan, Dipanjan; Kim, Benjamin; Hu, Grace; Gupta, Deepti Sood; Senpan, Angana; Yang, Xiaoxia; Schmieder, Anne; Swain, Corban; Wickline, Samuel A; Tomasson, Michael H; Lanza, Gregory M

    2015-01-01

    Aims The activity of the transcription factor c-Myc is dependent upon heterodimerization with Max to control target gene transcription. Small-molecule inhibitors of c-Myc–Max have exhibited low potency and poor water solubility and are therefore unsuitable for in vivo application. We hypothesized that a nanomedicine approach incorporating a cryptic c-Myc inhibitor prodrug could be delivered and enzymatically released in order to effectively inhibit melanoma. Materials & methods An Sn-2 lipase-labile Myc inhibitor prodrug was synthesized and included in two αvβ3-targeted nanoparticle platforms (20 and 200 nm). The inherent antiproliferate potency was compared with the lipid-free compound using human and mouse melanoma cell lines. Results & conclusion These data demonstrate for the first time a successful nanodelivery of c-Myc inhibitors and their potential use to prevent melanoma. PMID:25600969

  14. Deciphering c-MYC-regulated genes in two distinct tissues

    PubMed Central

    2011-01-01

    Background The transcription factor MYC is a critical regulator of diverse cellular processes, including both replication and apoptosis. Differences in MYC-regulated gene expression responsible for such opposing outcomes in vivo remain obscure. To address this we have examined time-dependent changes in global gene expression in two transgenic mouse models in which MYC activation, in either skin suprabasal keratinocytes or pancreatic islet β-cells, promotes tissue expansion or involution, respectively. Results Consistent with observed phenotypes, expression of cell cycle genes is increased in both models (albeit enriched in β-cells), as are those involved in cell growth and metabolism, while expression of genes involved in cell differentiation is down-regulated. However, in β-cells, which unlike suprabasal keratinocytes undergo prominent apoptosis from 24 hours, there is up-regulation of genes associated with DNA-damage response and intrinsic apoptotic pathways, including Atr, Arf, Bax and Cycs. In striking contrast, this is not the case for suprabasal keratinocytes, where pro-apoptotic genes such as Noxa are down-regulated and key anti-apoptotic pathways (such as Igf1-Akt) and those promoting angiogenesis are up-regulated. Moreover, dramatic up-regulation of steroid hormone-regulated Kallikrein serine protease family members in suprabasal keratinocytes alone could further enhance local Igf1 actions, such as through proteolysis of Igf1 binding proteins. Conclusions Activation of MYC causes cell growth, loss of differentiation and cell cycle entry in both β-cells and suprabasal keratinocytes in vivo. Apoptosis, which is confined to β-cells, may involve a combination of a DNA-damage response and downstream activation of pro-apoptotic signalling pathways, including Cdc2a and p19Arf/p53, and downstream targets. Conversely, avoidance of apoptosis in suprabasal keratinocytes may result primarily from the activation of key anti-apoptotic signalling pathways

  15. The Dysregulation of Polyamine Metabolism in Colorectal Cancer Is Associated with Overexpression of c-Myc and C/EBPβ rather than Enterotoxigenic Bacteroides fragilis Infection

    PubMed Central

    Snezhkina, Anastasiya V.; Lipatova, Anastasiya V.; Sadritdinova, Asiya F.; Kardymon, Olga L.; Fedorova, Maria S.; Kaprin, Andrey D.

    2016-01-01

    Colorectal cancer is one of the most common cancers in the world. It is well known that the chronic inflammation can promote the progression of colorectal cancer (CRC). Recently, a number of studies revealed a potential association between colorectal inflammation, cancer progression, and infection caused by enterotoxigenic Bacteroides fragilis (ETBF). Bacterial enterotoxin activates spermine oxidase (SMO), which produces spermidine and H2O2 as byproducts of polyamine catabolism, which, in turn, enhances inflammation and tissue injury. Using qPCR analysis, we estimated the expression of SMOX gene and ETBF colonization in CRC patients. We found no statistically significant associations between them. Then we selected genes involved in polyamine metabolism, metabolic reprogramming, and inflammation regulation and estimated their expression in CRC. We observed overexpression of SMOX, ODC1, SRM, SMS, MTAP, c-Myc, C/EBPβ (CREBP), and other genes. We found that two mediators of metabolic reprogramming, inflammation, and cell proliferation c-Myc and C/EBPβ may serve as regulators of polyamine metabolism genes (SMOX, AZIN1, MTAP, SRM, ODC1, AMD1, and AGMAT) as they are overexpressed in tumors, have binding site according to ENCODE ChIP-Seq data, and demonstrate strong coexpression with their targets. Thus, increased polyamine metabolism in CRC could be driven by c-Myc and C/EBPβ rather than ETBF infection. PMID:27433286

  16. Evidence for multiple sequences and factors involved in c-myc RNA stability during amphibian oogenesis.

    PubMed

    Lefresne, J; Lemaitre, J M; Selo, M; Goussard, J; Mouton, C; Andeol, Y

    2001-04-01

    To investigate the molecular mechanisms regulating c-myc RNA stability during late amphibian oogenesis, a heterologous system was used in which synthetic Xenopus laevis c-myc transcripts, progressively deleted from their 3' end, were injected into the cytoplasm of two different host axolotl (Ambystoma mexicanum) cells: stage VI oocytes and progesterone-matured oocytes (unfertilized eggs; UFE). This in vivo strategy allowed the behavior of the exogenous c-myc transcripts to be followed and different regions involved in the stability of each intermediate deleted molecule to be identified. Interestingly, these specific regions differ in the two cellular contexts. In oocytes, two stabilizing regions are located in the 3' untranslated region (UTR) and two in the coding sequence (exons II and III) of the RNA. In UFE, the stabilizing regions correspond to the first part of the 3' UTR and to the first part of exon II. However, in UFE, the majority of synthetic transcripts are degraded. This degradation is a consequence of nuclear factors delivered after germinal vesicle breakdown and specifically acting on targeted regions of the RNA. To test the direct implication of these nuclear factors in c-myc RNA degradation, an in vitro system was set up using axolotl germinal vesicle extracts that mimic the in vivo results and confirm the existence of specific destabilizing factors. In vitro analysis revealed that two populations of nuclear molecules are implicated: one of 4.4-5S (50-65 kDa) and the second of 5.4-6S (90-110 kDa). These degrading nuclear factors act preferentially on the coding region of the c-myc RNA and appear to be conserved between axolotl and Xenopus. Thus, this experimental approach has allowed the identification of specific stabilizing sequences in c-myc RNA and the temporal identification of the different factors (cytoplasmic and/or nuclear) involved in post-transcriptional regulation of this RNA during oogenesis. PMID:11284969

  17. Does radiation-induced c-MYC amplification initiate breast oncogenesis?

    PubMed Central

    Wade, Mark A; May, Felicity E B; Onel, Ken; Allan, James M

    2016-01-01

    The MYC (v-myc avian myelocytomatosis viral oncogene homolog; c-MYC) locus on chromosome 8q is susceptible to high-level amplification following exposure of human breast cells to ionizing radiation, and c-MYC amplification is a common feature of both radiogenic adenocarcinoma and radiogenic angiosarcoma of the breast. Taken together, these observations suggest common breast-specific susceptibility factors that predispose cells to amplification of this critical proto-oncogene and the development of radiogenic cancer in multiple tissue types of this radiosensitive organ. PMID:27308527

  18. Cooperative antiproliferative effect of coordinated ectopic expression of DLC1 tumor suppressor protein and silencing of MYC oncogene expression in liver cancer cells: Therapeutic implications

    PubMed Central

    Yang, Xuyu; Zhou, Xiaoling; Tone, Paul; Durkin, Marian E.; Popescu, Nicholas C.

    2016-01-01

    Human hepatocellular carcinoma (HCC) is one of the most common types of cancer and has a very poor prognosis; thus, the development of effective therapies for the treatment of advanced HCC is of high clinical priority. In the present study, the anti-oncogenic effect of combined knockdown of c-Myc expression and ectopic restoration of deleted in liver cancer 1 (DLC1) expression was investigated in human liver cancer cells. Expression of c-Myc in human HCC cells was knocked down by stable transfection with a Myc-specific short hairpin (sh) RNA vector. DLC1 expression in Huh7 cells was restored by adenovirus transduction, and the effects of DLC1 expression and c-Myc knockdown on Ras homolog gene family, member A (RhoA) levels, cell proliferation, soft agar colony formation and cell invasion were measured. Downregulation of c-Myc or re-expression of DLC1 led to a marked reduction in RhoA levels, which was associated with decreases in cell proliferation, soft agar colony formation and invasiveness; this inhibitory effect was augmented with a combination of DLC1 transduction and c-Myc suppression. To determine whether liver cell-specific delivery of DLC1 was able to enhance the inhibitory effect of c-Myc knockdown on tumor growth in vivo, DLC1 vector DNA complexed with galactosylated polyethylene glycol-linear polyethyleneimine was administered by tail vein injection to mice bearing subcutaneous xenografts of Huh7 cells transfected with shMyc or control shRNA. A cooperative inhibitory effect of DLC1 expression and c-Myc knockdown on the growth of Huh7-derived tumors was observed, suggesting that targeted liver cell delivery of DLC1 and c-Myc shRNA may serve as a possible gene therapy modality for the treatment of human HCC. PMID:27446476

  19. Susceptibility of striatal neurons to excitotoxic injury correlates with basal levels of Bcl-2 and the induction of P53 and c-Myc immunoreactivity.

    PubMed

    Liang, Zhong-Qin; Wang, Xiao-Xia; Wang, Yumei; Chuang, De-Maw; DiFiglia, Marian; Chase, Thomas N; Qin, Zheng-Hong

    2005-11-01

    The present studies evaluated the potential contribution of Bcl-2, p53, and c-Myc to the differential vulnerability of striatal neurons to the excitotoxin quinolinic acid (QA). In normal rat striatum, Bcl-2 immunoreactivity (Bcl-2-i) was most intense in large aspiny interneurons including choline acetyltransferase positive (CAT+) and parvalbumin positive (PARV+) neurons, but low in a majority of medium-sized neurons. In human brain, intense Bcl-2-i was seen in large striatal neurons but not in medium-sized spiny projection neurons. QA produced degeneration of numerous medium-sized neurons, but not those enriched in Bcl-2-i. Many Bcl-2-i-enriched interneurons including those with CAT+ and PARV+ survived QA injection, while medium-sized neurons labeled for calbindin D-28K (CAL D-28+) did not. In addition, proapoptotic proteins p53-i and c-Myc-i were robustly induced in medium-sized neurons, but not in most large neurons. The selective vulnerability of striatal medium spiny neurons to degeneration in a rodent model of Huntington's disease appears to correlate with their low levels of Bcl-2-i and high levels of induced p53-i and c-Myc-i. PMID:15922606

  20. Somatostatin reduces sup 3 H-thymidine incorporation and c-myc, but not thyroglobulin ribonucleic acid levels in human thyroid follicular cells in vitro

    SciTech Connect

    degli Uberti, E.C.; Hanau, S.; Rossi, R.; Piva, R.; Margutti, A.; Trasforini, G.; Pansini, G.; del Senno, L. )

    1991-06-01

    The action of somatostatin (SRIH) on {sup 3}H-thymidine (thy) incorporation and on c-myc and thyroglobulin RNA levels in a suspension of follicles from normal and goitrous human thyroid was examined. SRIH, at 10{sup {minus} 7} M concentration, inhibited basal thy incorporation (maximally by 4 h lasting for up 24 h), which effect was greater in goiter than in normal thyroid and was also detected in growing adherent epithelial cells. Moreover, in a follicle suspension SRIH prevented TSH-stimulated thy incorporation, both in normal and in goitrous thyroid. Basal expression of c-myc RNA was not affected by SRIH in either tissue, whereas the TSH-stimulated c-myc RNA level was significantly reduced in goiter. No effect of SRIH was observed on basal or TSH-stimulated thyroglobulin RNA levels. SRIH did not alter basal cAMP concentrations in normal or goitrous follicles, but it significantly reduced TSH-stimulated cAMP accumulation both in normal thyroid and in goiter. Overall, our data indicate a direct inhibitory action of SRIH on growth, but not on differentiation, of human thyroid, probably by a mechanism not entirely cAMP dependent.

  1. Factor-binding element in the human c-myc promoter involved in transcriptional regulation by transforming growth factor. beta. 1 and by the retinoblastoma gene product

    SciTech Connect

    Pietenpol, J.A.; Stein, R.W.; Moses, H.L. ); Muenger, K.; Howley, P.M. )

    1991-11-15

    Previous studies have shown that transforming growth factor {beta}1 (TGF-{beta}1) inhibition of keratinocyte proliferation involves suppression of c-myc transcription, and indirect evidence has suggested that the retinoblastoma gene product (pRB) may be involved in this process. In this study, transient expression of pRB in skin keratinocytes was shown to repress transcription of the human c-myc promoter region was required for regulation by both TGF-{beta}1 and pRB. These sequences, termed the TGF-{beta} control element (TCE), lie between positions {minus}86 and {minus}63 relative to the P1 transcription start site. Oligonucleotides containing the TCE bound to several nuclear factors in mobility-shift assays using extracts from cells with or without normal pRB. Binding of some factors was inhibited by TGF-{beta}1 treatment of TGF-{beta}-sensitive but not TGF-{beta}-insensitive cells. These data indicate that pRB can suppress c-myc transcription and growth inhibition.

  2. Aberrant immunoglobulin and c-myc gene rearrangements in patients with nonmalignant monoclonal cryoglobulinemia

    SciTech Connect

    Perl, A.; Wang, N.; Williams, J.M.; Hunt, M.J.; Rosenfeld, S.I.; Condemi, J.J.; Packman, C.H.; Abraham, G.N.

    1987-11-15

    The status of the immunoglobulin (Ig) genes was investigated in patients with idiopathic nonmalignant monoclonal IgG cryoglobulinemia (NCG). In NCG, monoclonal antibodies are synthesized at an accelerated rate by nonmalignant B lymphocytes. In order to determine whether this high production rate is related to a clonal B cell expansion, the rearrangement of the Ig genes was investigated by Southern blot analysis of genomic, /sup 32/P-labelled, DNA extracted from the peripheral blood lymphocytes of four NCG patients. In three of four (VI, BR, and CH) clonal expansion of B cells was detected using probes specific for the genes. BamHI digestion of DNA from VI and BR produced three rearranged fragments which cohybridized with two of the probes. This finding suggested the presence of additional nonsecretory B cell clones and/or disruption of the gene segments spanned by and detected with the probes. In addition, the possibility of aberrant gene rearrangements was supported by noting the alteration of the c-myc gene locus in genomic DNA from peripheral blood leukocytes of VI and CH. Northern blot analysis of RNA isolated from peripheral blood B cells of VI and CH demonstrated aberrant transcripts of the c-myc gene, showing an active role of the altered c-myc locus. Detection of c-myc rearrangement in NCG patients clearly shows that this event may not be a final step in malignant B cell transformation.

  3. Dose-adjusted Chemotherapy for Untreated c-MYC-positive Lymphoma

    Cancer.gov

    In this trial, adult patients with newly diagnosed Burkitt lymphoma or c-MYC-positive DLBCL will be separated into low-risk and high-risk groups; those in the low-risk group will be treated with at least three cycles of dose-adjusted EPOCH-R

  4. [Protein expression and purification].

    PubMed

    Růčková, E; Müller, P; Vojtěšek, B

    2014-01-01

    Production of recombinant proteins is essential for many applications in both basic research and also in medicine, where recombinant proteins are used as pharmaceuticals. This review summarizes procedures involved in recombinant protein expression and purification, including molecular cloning of target genes into expression vectors, selection of the appropriate expression system, and protein purification techniques. Recombinant DNA technology allows protein engineering to modify protein stability, activity and function or to facilitate protein purification by affinity tag fusions. A wide range of cloning systems enabling fast and effective design of expression vectors is currently available. A first choice of protein expression system is usually the bacteria Escherichia coli. The main advantages of this prokaryotic expression system are low cost and simplicity; on the other hand this system is often unsuitable for production of complex mammalian proteins. Protein expression mediated by eukaryotic cells (yeast, insect and mammalian cells) usually produces properly folded and posttranslationally modified proteins. How-ever, cultivation of insect and, especially, mammalian cells is time consuming and expensive. Affinity tagged recombinant proteins are purified efficiently using affinity chromatography. An affinity tag is a protein or peptide that mediates specific binding to a chromatography column, unbound proteins are removed during a washing step and pure protein is subsequently eluted. PMID:24945544

  5. Coexistent rearrangements of c-MYC, BCL2, and BCL6 genes in a diffuse large B-cell lymphoma.

    PubMed

    Ueda, Chiyoko; Nishikori, Momoko; Kitawaki, Toshio; Uchiyama, Takashi; Ohno, Hitoshi

    2004-01-01

    We present a patient with stage III de novo diffuse large B-cell lymphoma. The lymphoma cells showed mature B-cell immunophenotype but lacked surface immunoglobulin (Ig) expression. Long-distance and long-distance inverse polymerase chain reaction assays to detect the oncogene/Ig gene rearrangement revealed that the cells carried 3 independent fusion genes, namely, c-MYC/Ig heavy chain gene (IgH), BCL2/IgH, and Ig lambda light chain gene/BCL6. Thus, the lymphoma cells concurrently carried t(8;14)(q24;q32), t(14;18)(q32;q21), and t(3;22)(q27;q11), which developed in association with class switching, V/D/J recombination, and somatic hypermutation, respectively. The lymphoma responded to chemoradiotherapy, and the patient has been well for 2 years, suggesting that multiple oncogene rearrangements may not necessarily be associated with poor clinical outcome. PMID:14979479

  6. Oncogene amplification detected by in situ hybridization in radiation induced rat skin tumors. [C-myc:a3

    SciTech Connect

    Yi Jin.

    1991-02-01

    Oncogene activation may play an important role in radiation induced carcinogenesis. C-myc oncogene amplification was detected by in situ hybridization in radiation-induced rat skin tumors, including squamous and basal cell carcinomas. In situ hybridization was performed with a biotinylated human c-myc third exon probe, visualized with an avidin-biotinylated alkaline phosphate detection system. No c-myc oncogene amplification was detected in normal rat skin at very early times after exposure to ionizing radiation, which is consistent with the view that c-myc amplification is more likely to be related to carcinogenesis than to normal cell proliferation. The incorporation of tritiated thymidine into the DNA of rat skin cells showed that the proliferation of epidermal cells reached a peak on the seventh day after exposure to ionizing radiation and then decreased. No connection between the proliferation of epidermal cell and c-myc oncogene amplification in normal or irradiated rat skin was found. The results indicated that c-myc amplification as measured by in situ hybridization was correlated with the Southern bolt results, but only some of the cancer cells were amplified. The c-myc positive cells were distributed randomly within regions of the tumor and exhibited a more uniform nuclear structure in comparison to the more vacuolated c-myc negative cells. No c-myc signal was detected in unirradiated normal skin or in irradiated skin cells near the tumors. C-myc amplification appears to be cell or cell cycle specific within radiation-induced carcinomas. 28 refs., 3 figs., 3 tabs.

  7. A Nucleus-Imaging Probe That Selectively Stabilizes a Minor Conformation of c-MYC G-quadruplex and Down-regulates c-MYC Transcription in Human Cancer Cells

    PubMed Central

    Panda, Deepanjan; Debnath, Manish; Mandal, Samir; Bessi, Irene; Schwalbe, Harald; Dash, Jyotirmayee

    2015-01-01

    The c-MYC proto-oncogene is a regulator of fundamental cellular processes such as cell cycle progression and apoptosis. The development of novel c-MYC inhibitors that can act by targeting the c-MYC DNA G-quadruplex at the level of transcription would provide potential insight into structure-based design of small molecules and lead to a promising arena for cancer therapy. Herein we report our finding that two simple bis-triazolylcarbazole derivatives can inhibit c-MYC transcription, possibly by stabilizing the c-MYC G-quadruplex. These compounds are prepared using a facile and modular approach based on Cu(I) catalysed azide and alkyne cycloaddition. A carbazole ligand with carboxamide side chains is found to be microenvironment-sensitive and highly selective for “turn-on” detection of c-MYC quadruplex over duplex DNA. This fluorescent probe is applicable to visualize the cellular nucleus in living cells. Interestingly, the ligand binds to c-MYC in an asymmetric fashion and selects the minor-populated conformer via conformational selection. PMID:26286633

  8. Structure-based design of platinum(II) complexes as c-myc oncogene down-regulators and luminescent probes for G-quadruplex DNA.

    PubMed

    Wang, Ping; Leung, Chung-Hang; Ma, Dik-Lung; Yan, Siu-Cheong; Che, Chi-Ming

    2010-06-18

    A series of platinum(II) complexes with tridentate ligands was synthesized and their interactions with G-quadruplex DNA within the c-myc gene promoter were evaluated. Complex 1, which has a flat planar 2,6-bis(benzimidazol-2-yl)pyridine (bzimpy) scaffold, was found to stabilize the c-myc G-quadruplex structure in a cell-free system. An in silico G-quadruplex DNA model has been constructed for structure-based virtual screening to develop new Pt(II)-based complexes with superior inhibitory activities. By using complex 1 as the initial structure for hit-to-lead optimization, bzimpy and related 2,6-bis(pyrazol-3-yl)pyridine (dPzPy) scaffolds containing amine side-chains emerge as the top candidates. Six of the top-scoring complexes were synthesized and their interactions with c-myc G-quadruplex DNA have been investigated. The results revealed that all of the complexes have the ability to stabilize the c-myc G-quadruplex. Complex 3 a ([Pt(II)L2R](+); L2=2,6-bis[1-(3-piperidinepropyl)-1H-enzo[d]imidazol-2-yl]pyridine, R=Cl) displayed the strongest inhibition in a cell-free system (IC(50)=2.2 microM) and was 3.3-fold more potent than that of 1. Complexes 3 a and 4 a ([Pt(II)L3R](+); L3=2,6-bis[1-(3-morpholinopropyl)-1H-pyrazol-3-yl]pyridine, R=Cl) were found to effectively inhibit c-myc gene expression in human hepatocarcinoma cells with IC(50) values of approximately 17 microM, whereas initial hit 1 displayed no significant effect on gene expression at concentrations up to 50 microM. Complexes 3 a and 4 a have a strong preference for G-quadruplex DNA over duplex DNA, as revealed by competition dialysis experiments and absorption titration; 3 a and 4 a bind G-quadruplex DNA with binding constants (K) of approximately 10(6)-10(7) dm(3) mol(-1), which are at least an order of magnitude higher than the K values for duplex DNA. NMR spectroscopic titration experiments and molecular modeling showed that 4 a binds c-myc G-quadruplex DNA through an external end-stacking mode at

  9. Activation of NF-κB and AP-1 Mediates Hyperproliferation by Inducing β-Catenin and c-Myc in Helicobacter pylori-Infected Gastric Epithelial Cells

    PubMed Central

    Byun, Eunyoung; Park, Bohye; Lim, Joo Weon

    2016-01-01

    Purpose In the gastric mucosa of Helicobacter pylori (H. pylori)-infected patients with gastritis or adenocarcinoma, proliferation of gastric epithelial cells is increased. Hyperproliferation is related to induction of oncogenes, such as β-catenin and c-myc. Even though transcription factors NF-κB and AP-1 are activated in H. pylori-infected cells, whether NF-κB or AP-1 regulates the expression of β-catenein or c-myc in H. pylori-infected cells has not been clarified. The present study was undertaken to investigate whether H. pylori-induced activation of NF-κB and AP-1 mediates the expression of oncogenes and hyperproliferation of gastric epithelial cells. Materials and Methods Gastric epithelial AGS cells were transiently transfected with mutant genes for IκBα (MAD3) and c-Jun (TAM67) or treated with a specific NF-κB inhibitor caffeic acid phenethyl ester (CAPE) or a selective AP-1 inhibitor SR-11302 to suppress activation of NF-κB or AP-1, respecively. As reference cells, the control vector pcDNA was transfected to the cells. Wild-type cells or transfected cells were cultured with or without H. pylori. Results H. pylori induced activation of NF-κB and AP-1, cell proliferation, and expression of oncogenes (β-catenein, c-myc) in AGS cells, which was inhibited by transfection of MAD3 and TAM67. Wild-type cells and the cells transfected with pcDNA showed similar activities of NF-κB and AP-1, proliferation, and oncogene expression regardless of treatment with H. pylori. Both CAPE and SR-11302 inhibited cell proliferation and expression of oncogenes in H. pylori-infected cells. Conclusion H. pylori-induced activation of NF-κB and AP-1 regulates transcription of oncogenes and mediates hyperproliferation in gastric epithelial cells. PMID:26996564

  10. Transcriptional Suppression of mir-29b-1/mir-29a Promoter by c-Myc, Hedgehog, and NF-kappaB

    PubMed Central

    Mott, Justin L.; Kurita, Satoshi; Cazanave, Sophie; Bronk, Steven F.; Werneburg, Nathan W.; Fernandez-Zapico, Martin E.

    2010-01-01

    MicroRNAs regulate pathways contributing to oncogenesis, and thus the mechanisms causing dysregulation of microRNA expression in cancer are of significant interest. Mature mir-29b levels are decreased in malignant cells, and this alteration promotes the malignant phenotype, including apoptosis resistance. However, the mechanism responsible for mir-29b suppression is unknown. Here, we examined mir-29 expression from chromosome 7q32 using cholangiocarcinoma cells as a model for mir-29b downregulation. Using 5′ rapid amplification of cDNA ends, the transcriptional start site was identified for this microRNA locus. Computational analysis revealed the presence of two putative E-box (Myc-binding) sites, a Gli-binding site, and four NF–κB-binding sites in the region flanking the transcriptional start site. Promoter activity in cholangiocarcinoma cells was repressed by transfection with c-Myc, consistent with reports in other cell types. Treatment with the hedgehog inhibitor cyclopamine, which blocks smoothened signaling, increased the activity of the promoter and expression of mature mir-29b. Mutagenesis analysis and gel shift data are consistent with a direct binding of Gli to the mir-29 promoter. Finally, activation of NF–κB signaling, via ligation of Toll-like receptors, also repressed mir-29b expression and promoter function. Of note, activation of hedgehog, Toll-like receptor, and c-Myc signaling protected cholangiocytes from TRAIL-induced apoptosis. Thus, in addition to c-Myc, mir-29 expression can be suppressed by hedgehog signaling and inflammatory pathways, both commonly activated in the genesis of human malignancies. PMID:20564213

  11. Nuclear Matrix Protein 4 Is a Novel Regulator of Ribosome Biogenesis and Controls the Unfolded Protein Response via Repression of Gadd34 Expression.

    PubMed

    Young, Sara K; Shao, Yu; Bidwell, Joseph P; Wek, Ronald C

    2016-06-24

    The unfolded protein response (UPR) maintains protein homeostasis by governing the processing capacity of the endoplasmic reticulum (ER) to manage ER client loads; however, key regulators within the UPR remain to be identified. Activation of the UPR sensor PERK (EIFAK3/PEK) results in the phosphorylation of the α subunit of eIF2 (eIF2α-P), which represses translation initiation and reduces influx of newly synthesized proteins into the overloaded ER. As part of this adaptive response, eIF2α-P also induces a feedback mechanism through enhanced transcriptional and translational expression of Gadd34 (Ppp1r15A),which targets type 1 protein phosphatase for dephosphorylation of eIF2α-P to restore protein synthesis. Here we describe a novel mechanism by which Gadd34 expression is regulated through the activity of the zinc finger transcription factor NMP4 (ZNF384, CIZ). NMP4 functions to suppress bone anabolism, and we suggest that this occurs due to decreased protein synthesis of factors involved in bone formation through NMP4-mediated dampening of Gadd34 and c-Myc expression. Loss of Nmp4 resulted in an increase in c-Myc and Gadd34 expression that facilitated enhanced ribosome biogenesis and global protein synthesis. Importantly, protein synthesis was sustained during pharmacological induction of the UPR through a mechanism suggested to involve GADD34-mediated dephosphorylation of eIF2α-P. Sustained protein synthesis sensitized cells to pharmacological induction of the UPR, and the observed decrease in cell viability was restored upon inhibition of GADD34 activity. We conclude that NMP4 is a key regulator of ribosome biogenesis and the UPR, which together play a central role in determining cell viability during endoplasmic reticulum stress. PMID:27129771

  12. Site-Specific Oligonucleotide Binding Represses Transcription of the Human c-myc Gene in vitro

    NASA Astrophysics Data System (ADS)

    Cooney, Michael; Czernuszewicz, Graznya; Postel, Edith H.; Flint, S. Jane; Hogan, Michael E.

    1988-07-01

    A 27-base-long DNA oligonucleotide was designed that binds to duplex DNA at a single site within the 5' end of the human c-myc gene, 115 base pairs upstream from the transcription origin P1. On the basis of the physical properties of its bound complex, it was concluded that the oligonucleotide forms a colinear triplex with the duplex binding site. By means of an in vitro assay system, it was possible to show a correlation between triplex formation at -115 base pairs and repression of c-myc transcription. The possibility is discussed that triplex formation (site-specific RNA binding to a DNA duplex) could serve as the basis for an alternative program of gene control in vivo.

  13. Rearrangements of c-myc and c-abl genes in tumour cells in Burkitt's lymphoma.

    PubMed Central

    Casares, S; Rodríguez, J M; Martin, A; Parrado, A

    1993-01-01

    Rearrangements of oncogenes c-myc and c-abl were detected by non-radioactive hybridisation in a case of Burkitt's lymphoma/leukaemia. The surface phenotype of Burkitt's cells were positive for CD19, CD20, HLA-DR, CD14, CD33 and surface immunoglobulin markers. Although cytogenetic analysis was not performed, the c-myc and heavy immunoglobulin genes had the same 14.2 kilobase EcoRI molecular size fragment, suggesting a possible t(8;14) translocation which is a common marker of this malignancy. The c-abl oncogene was also rearranged in DNA digested BamHI and EcoRI. The physiopathological implications of the rearranged c-abl gene are unknown, this being the first case, as for as is known, of Burkitt's lymphoma/leukaemia with a rearranged c-abl gene. Images PMID:8408711

  14. KDM4B and KDM4A promote endometrial cancer progression by regulating androgen receptor, c-myc, and p27kip1

    PubMed Central

    Kwan, Suet-Ying; Chen, Limo; Chen, Jin-Hong; Ying, Zuo-Lin; Zhou, Ye; Gu, Wei; Wang, Li-Hua; Cheng, Wei-Wei; Zeng, Jianfang; Wan, Xiao-Ping; Mok, Samuel C.; Wong, Kwong-Kwok; Bao, Wei

    2015-01-01

    Epidemiological evidence suggests that elevated androgen levels and genetic variation related to the androgen receptor (AR) increase the risk of endometrial cancer (EC). However, the role of AR in EC is poorly understood. We report that two members of the histone demethylase KDM4 family act as major regulators of AR transcriptional activityin EC. In the MFE-296 cell line, KDM4B and AR upregulate c-myc expression, while in AN3CA cells KDM4A and AR downregulate p27kip1. Additionally, KDM4B expression is positively correlated with AR expression in EC cell lines with high baseline AR expression, while KDM4A and AR expression are positively correlated in low-AR cell lines. In clinical specimens, both KDM4B and KDM4A expression are significantly higher in EC tissues than that in normal endometrium. Finally, patients with alterations in AR, KDM4B, KDM4A, and c-myc have poor overall and disease-free survival rates. Together, these findings demonstrate that KDM4B and KDM4A promote EC progression by regulating AR activity. PMID:26397136

  15. KDM4B and KDM4A promote endometrial cancer progression by regulating androgen receptor, c-myc, and p27kip1.

    PubMed

    Qiu, Mei-Ting; Fan, Qiong; Zhu, Zhu; Kwan, Suet-Ying; Chen, Limo; Chen, Jin-Hong; Ying, Zuo-Lin; Zhou, Ye; Gu, Wei; Wang, Li-Hua; Cheng, Wei-Wei; Zeng, Jianfang; Wan, Xiao-Ping; Mok, Samuel C; Wong, Kwong-Kwok; Bao, Wei

    2015-10-13

    Epidemiological evidence suggests that elevated androgen levels and genetic variation related to the androgen receptor (AR) increase the risk of endometrial cancer (EC). However, the role of AR in EC is poorly understood. We report that two members of the histone demethylase KDM4 family act as major regulators of AR transcriptional activityin EC. In the MFE-296 cell line, KDM4B and AR upregulate c-myc expression, while in AN3CA cells KDM4A and AR downregulate p27kip1. Additionally, KDM4B expression is positively correlated with AR expression in EC cell lines with high baseline AR expression, while KDM4A and AR expression are positively correlated in low-AR cell lines. In clinical specimens, both KDM4B and KDM4A expression are significantly higher in EC tissues than that in normal endometrium. Finally, patients with alterations in AR, KDM4B, KDM4A, and c-myc have poor overall and disease-free survival rates. Together, these findings demonstrate that KDM4B and KDM4A promote EC progression by regulating AR activity. PMID:26397136

  16. Detection of immunoglobulin/c-myc recombinations in mice that are resistant to plasmacytoma induction.

    PubMed

    Müller, J R; Jones, G M; Potter, M; Janz, S

    1996-01-15

    Interchromosomal recombinations between c-myc and immunoglobulin sequences can be found in preneoplastic lesions (oil granulomata) during pristane-induced plasmacytoma development in susceptible BALB/cAn mice. In this study we used a more sensitive approach, hybridization-enriched templates with nested PCR, to detect microclones with Ig alpha/c-myc recombinations in oil granulomata of susceptible and resistant mice. Recombinations were detected in as many as 73% (32/44) of plasmacytoma-susceptible BALB/cAn mice 30 days after an injection of pristane. Mice that are resistant to plasmacytoma induction can also harbor recombination-positive cells, but these are less frequent [2/20 DBA/2N, 8/20 (BALB/cAn x DBA/2N)F1, hereafter called CD2F1]. The clones in DBA/2N mice were small (< 400 cells), whereas in BALB/cAn, the oil granuloma harbored up to several thousand of these cells. We conclude that the molecular machinery for generating characteristic interchromosomal recombinations can be found in all strains of mice. Both the frequency of generating Ig alpha/c-myc recombinations and the expansion of recombination-positive cells are greater in susceptible mice than in resistant strains. PMID:8542601

  17. An Epigenetic Pathway Regulates Sensitivity of Breast Cancer Cells to HER2 Inhibition via FOXO/c-Myc Axis

    PubMed Central

    Matkar, Smita; Sharma, Paras; Gao, Shubin; Gurung, Buddha; Katona, Bryson W; Liao, Jennifer; Muhammad, Abdul Bari; Kong, Xiang-Cheng; Wang, Lei; Jin, Guanghui; Dang, Chi; Hua, Xianxin

    2016-01-01

    SUMMARY Human epidermal growth factor receptor 2 (HER2) is upregulated in a subset of human breast cancers. However, the cancer cells often quickly develop an adaptive response to HER2 kinase inhibitors. We found that an epigenetic pathway involving MLL2 is crucial for growth of HER2+ cells and MLL2 reduces sensitivity of the cancer cells to a HER2 inhibitor, Lapatinib. Lapatinib-induced FOXO transcription factors, normally tumor-suppressing, paradoxically upregulate c-Myc epigenetically, in concert with a cascade of MLL2-associating epigenetic regulators, to dampen sensitivity of the cancer cells to Lapatinib. An epigenetic inhibitor suppressing c-Myc synergizes with Lapatinib to suppress cancer growth in vivo, partly by repressing the FOXO/c-Myc axis, unraveling an epigenetically regulated FOXO/c-Myc axis as a potential target to improve therapy. PMID:26461093

  18. Differences in the molecular structure of c-myc-activating recombinations in murine plasmacytomas and precursor cells.

    PubMed

    Müller, J R; Potter, M; Janz, S

    1994-12-01

    The translocation of c-myc on chromosome (chr.) 15 to an immunoglobulin heavy-chain switch region on chr. 12 is the critical oncogenic step in pristane-induced plasmacytoma (PCT) development in BALB/cAnPt mice. Applying a recently developed PCR method, we have been able to detect the most commonly occurring illegitimate recombinations between alpha-chain switch region (S alpha) and c-myc in preneoplastic B cells residing in mesenteric oil granuloma (OG) tissues 7-30 days postpristane. In this study, we compare the nucleotide sequences at the S alpha/c-myc breaksites on both the c-myc-activating chr. 12+ and the reciprocal chr. 15- from eight transplanted PCTs, seven primary PCTs, and five OGs that contained six B-cell clones. These junction sequences revealed a remarkable diversity of S alpha/c-myc recombinations. In nine cases--four PCTs and five B-cell clones--nearly precise reciprocal exchanges with a loss of only 3-35 bp in c-myc were found. Large deletions in c-myc that removed 369-878 bp were observed in seven PCTs but not in early B cells. Duplications of c-myc ranging from 103 to 229 bp were also restricted to PCTs and noticed in four cases. Clonally related but different reciprocal recombinations, 38 bp apart on chr. 12+ and 15 bp apart on chr. 15-, were isolated from two different specimens of the same OG tissue from a BALB/c mouse 30 days postpristane. A second OG from another 30-day mouse yielded four recombinational fragments--two clonally related chr. 12(+)-specific fragments and two chr. 15(-)-specific fragments--one of which carried a 143-bp insertion of a microsatellite at the breaksite. We suggest that the initial recombinational break-point regions between S alpha and c-myc in plasmacytoma precursor cells at the time of immunoglobulin heavy-chain switching are intrinsically labile and characterized by a persisting instability of c-myc, which can result in large secondary deletions of c-myc. PMID:7991585

  19. DNA binding and antigene activity of a daunomycin-conjugated triplex-forming oligonucleotide targeting the P2 promoter of the human c-myc gene

    PubMed Central

    Carbone, Giuseppina M.; McGuffie, Eileen; Napoli, Sara; Flanagan, Courtney E.; Dembech, Chiara; Negri, Umberto; Arcamone, Federico; Capobianco, Massimo L.; Catapano, Carlo V.

    2004-01-01

    Triplex-forming oligonucleotides (TFO) that bind DNA in a sequence-specific manner might be used as selective repressors of gene expression and gene-targeted therapeutics. However, many factors, including instability of triple helical complexes in cells, limit the efficacy of this approach. In the present study, we tested whether covalent linkage of a TFO to daunomycin, which is a potent DNA-intercalating agent and anticancer drug, could increase stability of the triple helix and activity of the oligonucleotide in cells. The 11mer daunomycin-conjugated GT (dauno-GT11) TFO targeted a sequence upstream of the P2 promoter, a site known to be critical for transcription of the c-myc gene. Band-shift assays showed that the dauno-GT11 formed triplex DNA with enhanced stability compared to the unmodified TFO. Band shift and footprinting experiments demonstrated that binding of dauno-GT11 was highly sequence-specific with exclusive binding to the 11 bp target site in the c-myc promoter. The daunomycin-conjugated TFO inhibited transcription in vitro and reduced c-myc promoter activity in prostate and breast cancer cells. The daunomycin-conjugated TFO was taken up by cells with a distinctive intracellular distribution compared to free daunomycin. However, cationic lipid-mediated delivery was required for enhanced cellular uptake, nuclear localization and biological activity of the TFO in cells. Dauno-GT11 reduced transcription of the endogenous c-myc gene in cells, but did not affect expression of non-target genes, such as ets-1 and ets-2, which contained very similar target sequences in their promoters. Daunomycin-conjugated control oligonucleotides unable to form triplex DNA with the target sequence did not have any effect in these assays, indicating that daunomycin was not directly responsible for the activity of daunomycin-conjugated TFO. Thus, attachment of daunomycin resulted in increased triplex stability and biological activity of the 11mer GT-rich TFO without

  20. Modulation of expression of genes encoding nuclear proteins following exposure to JANUS neutrons or {gamma}-rays

    SciTech Connect

    Woloschak, G.E.; Chang-Liu, Chin-Mei

    1994-05-01

    Previous work has shown that exposure of cells to ionizing radiations causes modulation of a variety of genes, including those encoding c-fos, interleukin-1, tumor necrosis factor, and cytoskeletal elements. The experiments reported herein were designed to examine the effects of either JANUS neutron or {gamma}-ray exposure on expression of genes encoding nucleus-associated proteins (H4-histone, c-jun, c-myc, Rb, and p53). Cycling Syrian hamster embryo cells were irradiated with varying doses and dose rates of either JANUS fission-spectrum neutrons or {gamma}-rays; after incubation of the cell cultures for 1 h following radiation exposure, mRNA was harvested and analyzed by Northern blot. Results revealed induction of transcripts for c-jun, H4-histone, and (to a lesser extent) Rb following {gamma}-ray but not following neutron exposure. Expression of p53 and c-myc genes was unaffected by radiation exposure. Radiations at different doses and dose rates were compared for each of the genes studied.

  1. The first exon of the c-myc proto-oncogene contains a novel positive control element.

    PubMed Central

    Yang, J Q; Remmers, E F; Marcu, K B

    1986-01-01

    We have identified a positive modulator within the c-myc first exon downstream of the gene's transcription initiation sites, P1 and P2. We introduced myc-CAT (chloramphenicol acetyltransferase) hybrid genes into three cell lines (BJAB, COS and HeLa) and measured their expression by either CAT enzymatic activity, S1 nuclease protection or by a nuclear 'run-on' transcription assay. Removal of 46 bp from the 3' end of the first exon results in a decrease of myc-CAT expression and P2 activity. A 438-bp exon 1 segment, lacking the normal myc promoters, efficiently drives the expression of SV40 early promoters. We find that this first exon segment efficiently functions as a positive modulator only in its sense orientation, 3' of a nearby promoter. The positive effects of the myc first exon and the SV40 enhancer are complementary. Images Fig. 2. Fig. 4. Fig. 5. Fig. 6. Fig. 7. Fig. 8. PMID:3030732

  2. Antileukemia Effect of Ciclopirox Olamine Is Mediated by Downregulation of Intracellular Ferritin and Inhibition β-Catenin-c-Myc Signaling Pathway in Glucocorticoid Resistant T-ALL Cell Lines

    PubMed Central

    Zhang, Ge; Gu, Ling; Zhang, Yanle; Gao, Ju; Wei, Yuquan

    2016-01-01

    Ciclopirox olamine (CPX) is an antifungal drug that has been reported to have antitumor effects. In this study we investigated the antileukemia effects and the possible mechanisms of CPX on glucocorticoid (GC)-resistant T-cell acute lymphoblastic leukemia (T-ALL) cell lines. The results indicated that CPX inhibited the growth of GC-resistant T-ALL cells in a time- and dose-dependent manner, and this effect was closely correlated with the downregulation of intracellular ferritin. CPX induced cell cycle arrest at G1 phase by upregulation of cyclin-dependent kinase (CDK) inhibitor of p21 and downregulation of the expressions of cyclin D, retinoblastoma protein (Rb), and phosphorylated Rb (pRb). CPX also enhanced apoptotic cell death by downregulation of anti-apoptotic proteins such as Bcl-2, Bcl-xL, and Mcl-1. More importantly, CPX demonstrated a strong synergistic antileukemia effect with GC and this effect was mediated, at least in part, by inhibition of the β-catenin-c-Myc signaling pathway. These findings suggest that CPX could be a promising antileukemia drug, and modulation of the intracellular ferritin expression might be an effective method in the treatment of ALL. Therefore, integrating CPX into the current GC-containing ALL protocols could lead to the improvement of the outcome of ALL, especially GC-resistant ALL. PMID:27551974

  3. Antileukemia Effect of Ciclopirox Olamine Is Mediated by Downregulation of Intracellular Ferritin and Inhibition β-Catenin-c-Myc Signaling Pathway in Glucocorticoid Resistant T-ALL Cell Lines.

    PubMed

    Wu, Jianrong; Liu, Huajun; Zhang, Ge; Gu, Ling; Zhang, Yanle; Gao, Ju; Wei, Yuquan; Ma, Zhigui

    2016-01-01

    Ciclopirox olamine (CPX) is an antifungal drug that has been reported to have antitumor effects. In this study we investigated the antileukemia effects and the possible mechanisms of CPX on glucocorticoid (GC)-resistant T-cell acute lymphoblastic leukemia (T-ALL) cell lines. The results indicated that CPX inhibited the growth of GC-resistant T-ALL cells in a time- and dose-dependent manner, and this effect was closely correlated with the downregulation of intracellular ferritin. CPX induced cell cycle arrest at G1 phase by upregulation of cyclin-dependent kinase (CDK) inhibitor of p21 and downregulation of the expressions of cyclin D, retinoblastoma protein (Rb), and phosphorylated Rb (pRb). CPX also enhanced apoptotic cell death by downregulation of anti-apoptotic proteins such as Bcl-2, Bcl-xL, and Mcl-1. More importantly, CPX demonstrated a strong synergistic antileukemia effect with GC and this effect was mediated, at least in part, by inhibition of the β-catenin-c-Myc signaling pathway. These findings suggest that CPX could be a promising antileukemia drug, and modulation of the intracellular ferritin expression might be an effective method in the treatment of ALL. Therefore, integrating CPX into the current GC-containing ALL protocols could lead to the improvement of the outcome of ALL, especially GC-resistant ALL. PMID:27551974

  4. Critical B-lymphoid cell intrinsic role of endogenous MCL-1 in c-MYC-induced lymphomagenesis.

    PubMed

    Grabow, S; Kelly, G L; Delbridge, A R D; Kelly, P N; Bouillet, P; Adams, J M; Strasser, A

    2016-01-01

    Evasion of apoptosis is critical for tumorigenesis, and sustained survival of nascent neoplastic cells may depend upon the endogenous levels of pro-survival BCL-2 family members. Indeed, previous studies using gene-targeted mice revealed that BCL-XL, but surprisingly not BCL-2, is critical for the development of c-MYC-induced pre-B/B lymphomas. However, it remains unclear whether another pro-survival BCL-2 relative contributes to their development. MCL-1 is an intriguing candidate, because it is required for cell survival during early B-lymphocyte differentiation. It is expressed abnormally high in several types of human B-cell lymphomas and is implicated in their resistance to chemotherapy. To test the B-cell intrinsic requirement for endogenous MCL-1 in lymphoma development, we conditionally deleted Mcl-1 in B-lymphoid cells of Eμ-Myc transgenic mice. We found that MCL-1 loss in early B-lymphoid progenitors delayed MYC-driven lymphomagenesis. Moreover, the lymphomas that arose when MCL-1 levels were diminished appeared to have been selected for reduced levels of BIM and/or increased levels of BCL-XL. These results underscore the importance of MCL-1 in lymphoma development and show that alterations in the levels of other cell death regulators can compensate for deficiencies in MCL-1 expression. PMID:26962682

  5. Critical B-lymphoid cell intrinsic role of endogenous MCL-1 in c-MYC-induced lymphomagenesis

    PubMed Central

    Grabow, S; Kelly, G L; Delbridge, A R D; Kelly, P N; Bouillet, P; Adams, J M; Strasser, A

    2016-01-01

    Evasion of apoptosis is critical for tumorigenesis, and sustained survival of nascent neoplastic cells may depend upon the endogenous levels of pro-survival BCL-2 family members. Indeed, previous studies using gene-targeted mice revealed that BCL-XL, but surprisingly not BCL-2, is critical for the development of c-MYC-induced pre-B/B lymphomas. However, it remains unclear whether another pro-survival BCL-2 relative contributes to their development. MCL-1 is an intriguing candidate, because it is required for cell survival during early B-lymphocyte differentiation. It is expressed abnormally high in several types of human B-cell lymphomas and is implicated in their resistance to chemotherapy. To test the B-cell intrinsic requirement for endogenous MCL-1 in lymphoma development, we conditionally deleted Mcl-1 in B-lymphoid cells of Eμ-Myc transgenic mice. We found that MCL-1 loss in early B-lymphoid progenitors delayed MYC-driven lymphomagenesis. Moreover, the lymphomas that arose when MCL-1 levels were diminished appeared to have been selected for reduced levels of BIM and/or increased levels of BCL-XL. These results underscore the importance of MCL-1 in lymphoma development and show that alterations in the levels of other cell death regulators can compensate for deficiencies in MCL-1 expression. PMID:26962682

  6. Differential Selection of Cells with Proviral c-myc and c-erbB Integrations after Avian Leukosis Virus Infection

    PubMed Central

    Gong, Min; Semus, Helen L.; Bird, Kelly J.; Stramer, Brian J.; Ruddell, Alanna

    1998-01-01

    Avian leukosis virus (ALV) infection induces bursal lymphomas in chickens after proviral integration within the c-myc proto-oncogene and induces erythroblastosis after integration within the c-erbB proto-oncogene. A nested PCR assay was used to analyze the appearance of these integrations at an early stage of tumor induction after infection of embryos. Five to eight distinct proviral c-myc integration events were amplified from bursas of infected 35-day-old birds, in good agreement with the number of transformed bursal follicles arising with these integrations. Cells containing these integrations are remarkably common, with an estimated 1 in 350 bursal cells having proviral c-myc integrations. These integrations were clustered within the 3′ half of c-myc intron 1, in a pattern similar to that observed in bursal lymphomas. Bone marrow and spleen showed a similar number and pattern of integrations clustered within 3′ c-myc intron 1, indicating that this region is a common integration target whether or not that tissue undergoes tumor induction. While all tissues showed equivalent levels of viral infection, cells with c-myc integrations were much more abundant in the bursa than in other tissues, indicating that cells with proviral c-myc integrations are preferentially expanded within the bursal environment. Proviral integration within the c-erbB gene was also analyzed, to detect clustered c-erbB intron 14 integrations associated with erythroblastosis. Proviral c-erbB integrations were equally abundant in the bone marrow, spleen, and bursa. These integrations were randomly situated upstream of c-erbB exon 15, indicating that cells carrying 3′ intron 14 integrations must be selected during induction of erythroblastosis. PMID:9621008

  7. Far upstream element-binding protein 1 is a prognostic biomarker and promotes nasopharyngeal carcinoma progression

    PubMed Central

    Liu, Z-H; Hu, J-L; Liang, J-Z; Zhou, A-J; Li, M-Z; Yan, S-M; Zhang, X; Gao, S; Chen, L; Zhong, Q; Zeng, M-S

    2015-01-01

    Nasopharyngeal carcinoma (NPC) is a malignant epithelial tumor with tremendous invasion and metastasis capacities, and it has a high incidence in southeast Asia and southern China. Previous studies identified that far upstream element-binding protein 1 (FBP1), a transcriptional regulator of c-Myc that is one of the most frequently aberrantly expressed oncogenes in various human cancers, including NPC, is an important biomarker for many cancers. Our study aimed to investigate the expression and function of FBP1 in human NPC. Quantitative real-time RT-PCR (qRT-PCR), western blot and immunohistochemical staining (IHC) were performed in NPC cells and biopsies. Furthermore, the effect of FBP1 knockdown on cell proliferation, colony formation, side population tests and tumorigenesis in nude mice were measured by MTT, clonogenicity analysis, flow cytometry and a xenograft model, respectively. The results showed that the mRNA and protein levels of FBP1, which are positively correlated with c-Myc expression, were substantially higher in NPC than that in nasopharyngeal epithelial cells. IHC revealed that the patients with high FBP1 expression had a significantly poorer prognosis compared with the patients with low expression (P=0.020). In univariate analysis, high FBP1 and c-Myc expression predicted poorer overall survival (OS) and poorer progression-free survival. Multivariate analysis indicated that high FBP1 and c-Myc expression were independent prognostic markers. Knockdown of FBP1 reduced cell proliferation, clonogenicity and the ratio of side populations, as well as tumorigenesis in nude mice. These data indicate that FBP1 expression, which is closely correlated with c-Myc expression, is an independent prognostic factor and promotes NPC progression. Our results suggest that FBP1 can not only serve as a useful prognostic biomarker for NPC but also as a potential therapeutic target for NPC patients. PMID:26469968

  8. Effect of c-myc on the ultrastructural structure of cochleae in guinea pigs with noise induced hearing loss

    SciTech Connect

    Han, Yu; Zhong, Cuiping; Hong, Liu; Wang, Ye; Qiao, Li; Qiu, Jianhua

    2009-12-18

    Noise over-stimulation may induce hair cells loss and hearing deficit. The c-myc oncogene is a major regulator for cell proliferation, growth, and apoptosis. However, the role of this gene in the mammalian cochlea is still unclear. The study was designed to firstly investigate its function under noise condition, from the aspect of cochlear ultrastructural changes. We had established the adenoviral vector of c-myc gene and delivered the adenovirus suspension into the scala tympani of guinea pigs 4 days before noise exposure. The empty adenoviral vectors were injected as control. Then, all subjects were exposed to 4-kHz octave-band noise at 110 dB SPL for 8 h/day, 3 days consecutively. Auditory thresholds were assessed by auditory brainstem response, prior to and 7 days following noise exposure. On the seventh days after noise exposure, the cochlear sensory epithelia surface was observed microscopically and the cochleae were taken to study the ultrastructural changes. The results indicated that auditory threshold shift after noise exposure was higher in the ears treated with Ad.EGFP than that treated with Ad.c-myc-EGFP. Stereocilia loss and the disarrangement of outer hair cells were observed, with greater changes found in the Ad.EGFP group. Also, the ultrastructure changes were severe in the Ad.EGFP group, but not obvious in the Ad.c-myc-EGFP group. Therefore, c-myc gene might play an unexpected role in hearing functional and morphological protection from acoustic trauma.

  9. 5-aza-2'-deoxycytidine-mediated c-myc Down-regulation triggers telomere-dependent senescence by regulating human telomerase reverse transcriptase in chronic myeloid leukemia.

    PubMed

    Grandjenette, Cindy; Schnekenburger, Michael; Karius, Tommy; Ghelfi, Jenny; Gaigneaux, Anthoula; Henry, Estelle; Dicato, Mario; Diederich, Marc

    2014-06-01

    Increased proliferation rates as well as resistance to apoptosis are considered major obstacles for the treatment of patients with chronic myelogenous leukemia (CML), thus highlighting the need for novel therapeutic approaches. Since senescence has been recognized as a physiological barrier against tumorigenesis, senescence-based therapy could represent a new strategy against CML. DNA demethylating agent 5-aza-2'-deoxycytidine (DAC) was reported to induce cellular senescence but underlying mechanisms remain to be elucidated. Here, we report that exposure to DAC triggers senescence in chronic leukemia cell lines as evidenced by increased senescence-associated β-galactosidase activity and lysosomal mass, accompanied by an up-regulation of cell cycle-related genes. We provide evidence that DAC is able to decrease telomere length, to reduce telomerase activity and to decrease human telomerase reverse transcriptase (hTERT) expression through decreased binding of c-myc to the hTERT promoter. Altogether, our results reveal the role of c-myc in telomere-dependent DAC-induced senescence and therefore provide new clues for improving chronic human leukemia treatments. PMID:24970385

  10. MicroRNA Replacing Oncogenic Klf4 and c-Myc for Generating iPS Cells via Cationized Pleurotus eryngii Polysaccharide-based Nanotransfection.

    PubMed

    Deng, Wenwen; Cao, Xia; Chen, Jingjing; Zhang, Zhijian; Yu, Qingtong; Wang, Yan; Shao, Genbao; Zhou, Jie; Gao, Xiangdong; Yu, Jiangnan; Xu, Ximing

    2015-09-01

    Induced pluripotent stem cells (iPSCs), resulting from the forced expression of cocktails out of transcription factors, such as Oct4, Sox2, Klf4, and c-Myc (OSKM), has shown tremendous potential in regenerative medicine. Although rapid progress has been made recently in the generation of iPSCs, the safety and efficiency remain key issues for further application. In this work, microRNA 302-367 was employed to substitute the oncogenic Klf4 and c-Myc in the OSKM combination as a safer strategy for successful iPSCs generation. The negatively charged plasmid mixture (encoding Oct4, Sox2, miR302-367) and the positively charged cationized Pleurotus eryngii polysaccharide (CPEPS) self-assembled into nanosized particles, named as CPEPS-OS-miR nanoparticles, which were applied to human umbilical cord mesenchymal stem cells for iPSCs generation after characterization of the physicochemical properties. The CPEPS-OS-miR nanoparticles possessed spherical shape, ultrasmall particle size, and positive surface charge. Importantly, the combination of plasmids Oct4, Sox2, and miR302-367 could not only minimize genetic modification but also show a more than 50 times higher reprogramming efficiency (0.044%) than any other single or possible double combinations of these factors (Oct4, Sox2, miR302-367). Altogether, the current study offers a simple, safe, and effective self-assembly approach for generating clinically applicable iPSCs. PMID:26269400

  11. miR-23b/SP1/c-myc forms a feed-forward loop supporting multiple myeloma cell growth

    PubMed Central

    Fulciniti, M; Amodio, N; Bandi, R L; Cagnetta, A; Samur, M K; Acharya, C; Prabhala, R; D'Aquila, P; Bellizzi, D; Passarino, G; Adamia, S; Neri, A; Hunter, Z R; Treon, S P; Anderson, K C; Tassone, P; Munshi, N C

    2016-01-01

    Deregulated microRNA (miR)/transcription factor (TF)-based networks represent a hallmark of cancer. We report here a novel c-Myc/miR-23b/Sp1 feed-forward loop with a critical role in multiple myeloma (MM) and Waldenstrom's macroglobulinemia (WM) cell growth and survival. We have found miR-23b to be downregulated in MM and WM cells especially in the presence of components of the tumor bone marrow milieu. Promoter methylation is one mechanism of miR-23b suppression in myeloma. In gain-of-function studies using miR-23b mimics-transfected or in miR-23b-stably expressing MM and WM cell lines, we observed a significant decrease in cell proliferation and survival, along with induction of caspase-3/7 activity over time, thus supporting a tumor suppressor role for miR-23b. At the molecular level, miR-23b targeted Sp1 3′UTR and significantly reduced Sp1-driven nuclear factor-κB activity. Finally, c-Myc, an important oncogenic transcription factor known to stimulate MM cell proliferation, transcriptionally repressed miR-23b. Thus MYC-dependent miR-23b repression in myeloma cells may promote activation of oncogenic Sp1-mediated signaling, representing the first feed-forward loop with critical growth and survival role in myeloma. PMID:26771806

  12. mTOR/MYC Axis Regulates O-GlcNAc Transferase (OGT) Expression and O-GlcNAcylation in Breast Cancer

    PubMed Central

    Sodi, Valerie L.; Khaku, Sakina; Krutilina, Raisa; Schwab, Luciana P.; Vocadlo, David J.; Seagroves, Tiffany N.; Reginato, Mauricio J.

    2015-01-01

    Cancers exhibit altered metabolism characterized by increased glucose and glutamine uptake. The hexosamine biosynthetic pathway (HBP) utilizes glucose and glutamine, and directly contributes to O-linked-β-N-acetylglucosamine (O-GlcNAc) modifications on intracellular proteins. Multiple tumor types contain elevated total O-GlcNAcylation, in part, by increasing O-GlcNAc transferase (OGT) levels, the enzyme that catalyzes this modification. Although cancer cells require OGT for oncogenesis, it is not clear how tumor cells regulate OGT expression and O-GlcNAcylation. Here, it is shown that the PI3K/mTOR/MYC signaling pathway is required for elevation of OGT and O-GlcNAcylation in breast cancer cells. Treatment with PI3K and mTOR inhibitors reduced OGT protein expression and decreased levels of overall O-GlcNAcylation. In addition, both AKT and mTOR activation is sufficient to elevate OGT/O-GlcNAcylation. Downstream of mTOR, the oncogenic transcription factor c-MYC is required and sufficient for increased OGT protein expression in an RNA-independent manner and c-MYC regulation of OGT mechanistically requires the expression of c-MYC transcriptional target HSP90A. Lastly, mammary tumor epithelial cells derived from MMTV-c-myc transgenic mice contain elevated OGT and O-GlcNAcylation and OGT inhibition in this model induces apoptosis. Thus, OGT and O-GlcNAcylation levels are elevated via activation of an mTOR/MYC cascade. PMID:25636967

  13. Targeted Knockdown of RNA-Binding Protein TIAR for Promoting Self-Renewal and Attenuating Differentiation of Mouse Embryonic Stem Cells.

    PubMed

    Geng, Zhe; Li, Ping; Tan, Li; Song, Houyan

    2015-01-01

    RNA-binding protein TIAR has been suggested to mediate the translational silencing of ARE-containing mRNAs. To analyze the functions of TIAR, we established RNAi and genetic rescue assays. We evaluated the expression of neuroectoderm markers Pax6 and nestin, mesoderm markers brachyury and Flk1, and hypoblast and definitive endoderm markers Sox17 and Gata6 during EB differentiation and found that knockdown TIAR expression restrained the differentiation of E14 cells. We assessed gene expression levels of Flk-1 and VE-cadherin and observed attenuated differentiation of E14 cells into endothelial cells upon downregulation of TIAR gene expression. As such, we hypothesized an essential role of TIAR related to EB differentiation. As TIAR inhibits the translation of c-myc, we proposed that downregulation of TIAR results in restrained differentiation of E14 cells, due in part to the function of c-myc. We found that TIAR inhibited c-myc expression at the translational level in E14 cells; accordingly, a reduction of TIAR expression promoted self-renewal of pluripotent cells and attenuated differentiation. Additionally, we established that TIAR inhibited TIA-1 expression at the translational level in E14 cells. Taken together, we have contributed to the understanding of the regulatory relationships between TIAR and both c-myc and TIA-1. PMID:25918534

  14. Long noncoding RNA ANRIL could be transactivated by c-Myc and promote tumor progression of non-small-cell lung cancer

    PubMed Central

    Lu, Yi; Zhou, Xiaohui; Xu, Ling; Rong, Chaohui; Shen, Ce; Bian, Wei

    2016-01-01

    In recent years, long noncoding RNAs (lncRNAs) have been demonstrated to play important roles in the development of human cancer. We assessed the role of lncRNA ANRIL in non-small-cell lung cancer (NSCLC). Quantitative real-time polymerase chain reaction was employed to detect the expression of ANRIL in NSCLC tissues and paired nontumor tissues. The high expression level of ANRIL was positively correlated with advanced tumor–node–metastasis stage and greater tumor diameter. Furthermore, chromatin immunoprecipitation assays confirmed the physical interaction between c-Myc and ANRIL. ANRIL silencing significantly inhibited NSCLC cell proliferation. Together, we showed that ANRIL is involved in the oncogenesis of NSCLC, and ANRIL may be a potential therapeutic target for patients with NSCLC. PMID:27307748

  15. Bisaryldiketene derivatives: A new class of selective ligands for c-myc G-quadruplex DNA.

    PubMed

    Peng, Dan; Tan, Jia-Heng; Chen, Shuo-Bin; Ou, Tian-Miao; Gu, Lian-Quan; Huang, Zhi-Shu

    2010-12-01

    A series of bisaryldiketene derivatives were designed and synthesized as a new class of specific G-quadruplex ligands. The ligand-quadruplex interactions were further evaluated by FRET, ITC, and PCR stop assay. In contrast to most of the G-quadruplex ligands reported so far, which comprise an extended aromatic ring, these compounds are neither polycyclic nor macrocyclic, but have a non-aromatic and relative flexible linker between two quinoline moieties enabling the conformation of compounds to be flexible. Our results showed that these bisaryldiketene derivatives could selectively recognize G-quadruplex DNA rather than binding to duplex DNA. Moreover, they showed promising discrimination between different G-quadruplex DNA. The primary binding affinity of ligand M2 for c-myc G-quadruplex DNA was over 200 times larger than that for telomere G-quadruplex DNA. PMID:21036049

  16. Transcriptome Analysis of WHV/c-myc Transgenic Mice Implicates Cytochrome P450 Enzyme 17A1 as a Promising Biomarker for Hepatocellular Carcinoma.

    PubMed

    Wang, Feng; Huang, Jian; Zhu, Zhu; Ma, Xiao; Cao, Li; Zhang, Yongzhi; Chen, Wei; Dong, Yang

    2016-09-01

    Early detection of hepatocellular carcinoma (HCC) is critical for successful treatment and favorable prognosis. To identify novel HCC biomarkers, we used the WHV/c-myc transgenic (Tg) mice, an animal model of hepatocarcinogenesis. By analyzing their gene expression profiling, we investigated differentially expressed genes in livers of wild-type and Tg mice. The cytochrome P450, family 17, subfamily A, polypeptide 1 (CYP17A1), a hepatic P450 enzyme, was revealed to be overexpressed in the liver tissues of Tg mice at both preneoplastic and neoplastic stages. Mouse-to-human validation demonstrated that CYP17A1 mRNA and protein were also significantly increased in human HCC tissues compared with paired nontumor tissues (P = 0.00041 and 0.00011, respectively). Immunohistochemical studies showed that CYP17A1 was overexpressed in 67% (58 of 87) of HCC, and strong staining of CYP17A1 was observed in well-differentiated HCCs. Consistent with this, the median serum levels of CYP17A1 were also significantly higher in patients with HCC (140.2 ng/mL, n = 776) compared with healthy controls (31.4 ng/mL, n = 366) and to those with hepatitis B virus (57.5 ng/mL, n = 160), cirrhosis (46.1 ng/mL, n = 147), lung cancer (27.4 ng/mL, n = 109), and prostate cancer (42.1 ng/mL, n = 130; all P < 0.001). Notably, the elevations were seen in most AFP-negative HCC cases. Altogether, through mouse-to-human search and validation, we found that CYP17A1 is overexpressed in HCCs and it has great potentiality as a noninvasive marker for HCC detection. These results provide a rationale for the future development and clinical application of CYP17A1 measurement to diagnose HCC more precisely. Cancer Prev Res; 9(9); 739-49. ©2016 AACR. PMID:27339169

  17. Engineered zinc-finger transcription factors activate OCT4 (POU5F1), SOX2, KLF4, c-MYC (MYC) and miR302/367.

    PubMed

    Ji, Qingzhou; Fischer, Ashley L; Brown, Clyde R; Eastlund, Erik R; Dvash, Tamar; Zhong, Bonan; Gerber, Mark A; Lyons, Ian; Knight, Scott W; Kreader, Carol A

    2014-06-01

    Artificial transcription factors are powerful tools for regulating gene expression. Here we report results with engineered zinc-finger transcription factors (ZF-TFs) targeting four protein-coding genes, OCT4, SOX2, KLF4 and c-MYC, and one noncoding ribonucleic acid (RNA) gene, the microRNA (miRNA) miR302/367 cluster. We designed over 300 ZF-TFs whose targets lie within 1 kb of the transcriptional start sites (TSSs), screened them for increased messenger RNA or miRNA levels in transfected cells, and identified potent ZF-TF activators for each gene. Furthermore, we demonstrate that selected ZF-TFs function with alternative activation domains and in multiple cell lines. For OCT4, we expanded the target range to -2.5 kb and +500 bp relative to the TSS and identified additional active ZF-TFs, including three highly active ZF-TFs targeting distal enhancer, proximal enhancer and downstream from the proximal promoter. Chromatin immunoprecipitation (FLAG-ChIP) results indicate that several inactive ZF-TFs targeting within the same regulatory region bind as well as the most active ZF-TFs, suggesting that efficient binding within one of these regulatory regions may be necessary but not sufficient for activation. These results further our understanding of ZF-TF design principles and corroborate the use of ZF-TFs targeting enhancers and downstream from the TSS for transcriptional activation. PMID:24792165

  18. Engineered zinc-finger transcription factors activate OCT4 (POU5F1), SOX2, KLF4, c-MYC (MYC) and miR302/367

    PubMed Central

    Ji, Qingzhou; Fischer, Ashley L.; Brown, Clyde R.; Eastlund, Erik R.; Dvash, Tamar; Zhong, Bonan; Gerber, Mark A.; Lyons, Ian; Knight, Scott W.; Kreader, Carol A.

    2014-01-01

    Artificial transcription factors are powerful tools for regulating gene expression. Here we report results with engineered zinc-finger transcription factors (ZF-TFs) targeting four protein-coding genes, OCT4, SOX2, KLF4 and c-MYC, and one noncoding ribonucleic acid (RNA) gene, the microRNA (miRNA) miR302/367 cluster. We designed over 300 ZF-TFs whose targets lie within 1 kb of the transcriptional start sites (TSSs), screened them for increased messenger RNA or miRNA levels in transfected cells, and identified potent ZF-TF activators for each gene. Furthermore, we demonstrate that selected ZF-TFs function with alternative activation domains and in multiple cell lines. For OCT4, we expanded the target range to −2.5 kb and +500 bp relative to the TSS and identified additional active ZF-TFs, including three highly active ZF-TFs targeting distal enhancer, proximal enhancer and downstream from the proximal promoter. Chromatin immunoprecipitation (FLAG-ChIP) results indicate that several inactive ZF-TFs targeting within the same regulatory region bind as well as the most active ZF-TFs, suggesting that efficient binding within one of these regulatory regions may be necessary but not sufficient for activation. These results further our understanding of ZF-TF design principles and corroborate the use of ZF-TFs targeting enhancers and downstream from the TSS for transcriptional activation. PMID:24792165

  19. AMPK inhibits MTDH expression via GSK3β and SIRT1 activation: potential role in triple negative breast cancer cell proliferation.

    PubMed

    Gollavilli, Paradesi Naidu; Kanugula, Anantha Koteswararao; Koyyada, Rajeswari; Karnewar, Santosh; Neeli, Praveen Kumar; Kotamraju, Srigiridhar

    2015-10-01

    Recent studies have highlighted the involvement of metadherin (MTDH), an oncogenic protein, in promoting cancer progression, metastasis and chemoresistance in many cancers including mammary carcinomas. However, the molecular regulation of MTDH is still not completely understood. In this study we document that AMP activated protein kinase (AMPK) activation-induced anti-proliferative effects are, in part, mediated by inhibiting MTDH expression in MDA-MB-231 and BT-549 triple negative breast cancer (TNBC) cells. 5-Aminoimidazole-4-carboxamide ribonucleotide (AICAR), an AMPK activator, caused growth arrest, inhibition of migration and invasion of TNBC cells. Intriguingly, AICAR or metformin treatment resulted in significant downregulation of MTDH expression via inhibiting c-Myc expression. In contrast, treatment of cells with compound C, an inhibitor of AMPK, increased both c-Myc and MTDH expressions in TNBC cells. Also, AMPK activation caused increased glycogen synthase kinase 3β (GSK3β) activity by inhibiting the inactive phosphorylation at Ser9, on the one hand, and activation of sirtuin1 (SIRT1) by inhibiting Ser47 phosphorylation, as evidenced by deacetylation of p53, on the other hand. Moreover, AMPK-induced GSK3β and SIRT1 activities were found to be responsible for inhibiting c-Myc-mediated upregulation of MTDH, as LiCl (an inhibitor of GSK3β) and EX-527 (an inhibitor of SIRT1) reversed AICAR-mediated downregulation of c-Myc and MTDH expressions. Similar results were observed with siSIRT1 treatment. Furthermore, AICAR and EX-527 treatments caused increased cell death under MTDH-depleted conditions. Finally, we uncovered a novel regulation of MTDH expression and showed that AMPK activation by inducing GSK3β and SIRT1 downregulates MTDH expression via inhibiting c-Myc in TNBC cells. PMID:26236947

  20. MicroRNA-155 controls affinity-based selection by protecting c-MYC+ B cells from apoptosis

    PubMed Central

    Nakagawa, Rinako; Leyland, Rebecca; Meyer-Hermann, Michael; Lu, Dong; Turner, Martin; Arbore, Giuseppina; Phan, Tri Giang; Brink, Robert; Vigorito, Elena

    2015-01-01

    The production of high-affinity antibodies by B cells is essential for pathogen clearance. Antibody affinity for antigen is increased through the affinity maturation in germinal centers (GCs). This is an iterative process in which B cells cycle between proliferation coupled with the acquisition of mutations and antigen-based positive selection, resulting in retention of the highest-affinity B cell clones. The posttranscriptional regulator microRNA-155 (miR-155) is critical for efficient affinity maturation and the maintenance of the GCs; however, the cellular and molecular mechanism by which miR-155 regulates GC responses is not well understood. Here, we utilized a miR-155 reporter mouse strain and showed that miR-155 is coexpressed with the proto-oncogene encoding c-MYC in positively selected B cells. Functionally, miR-155 protected positively selected c-MYC+ B cells from apoptosis, allowing clonal expansion of this population, providing an explanation as to why Mir155 deletion impairs affinity maturation and promotes the premature collapse of GCs. We determined that miR-155 directly inhibits the Jumonji family member JARID2, which enhances B cell apoptosis when overexpressed, and thereby promotes GC B cell survival. Our findings also suggest that there is cooperation between c-MYC and miR-155 during the normal GC response, a cooperation that may explain how c-MYC and miR-155 can collaboratively function as oncogenes. PMID:26657861

  1. Identification of Epstein-Barr Virus (EBV) Nuclear Antigen 2 (EBNA2) Target Proteins by Proteome Analysis: Activation of EBNA2 in Conditionally Immortalized B Cells Reflects Early Events after Infection of Primary B Cells by EBV

    PubMed Central

    Schlee, Martin; Krug, Tanja; Gires, Olivier; Zeidler, Reinhard; Hammerschmidt, Wolfgang; Mailhammer, Reinhard; Laux, Gerhard; Sauer, Guido; Lovric, Josip; Bornkamm, Georg W.

    2004-01-01

    The Epstein-Barr virus (EBV) is a ubiquitous B-lymphotropic herpesvirus associated with several malignant tumors, e.g., Burkitt's lymphoma and Hodgkin's disease, and is able to efficiently immortalize primary B lymphocytes in vitro. The growth program of infected B cells is initiated and maintained by the viral transcription factor EBV nuclear antigen 2 (EBNA2), which regulates viral and cellular genes, including the proto-oncogene c-myc. In our study, patterns of protein expression in B cells with and without EBNA2 were analyzed by two-dimensional polyacrylamide gel electrophoresis and mass spectrometry. For this purpose, we used a conditional immortalization system for EBV, a B cell line (EREB2-5) that expresses an estrogen receptor-EBNA2 fusion protein. In order to discriminate downstream targets of c-Myc from c-Myc-independent EBNA2 targets, we used an EREB2-5-derived cell line, P493-6, in which c-Myc is expressed under the control of a tetracycline-regulated promoter. Of 20 identified EBNA2 target proteins, 11 were c-Myc dependent and therefore most probably associated with proliferation, and one of these proteins was a posttranslationally modified protein, i.e., hypusinylated eIF5a. Finally, to estimate the relevance of EBNA2 targets during early EBV infection, we analyzed the proteomes of primary B cells before and after infection with EBV. The protein expression pattern induced upon EBV infection was similar to that following EBNA2 activation. These findings underscore the value of EREB2-5 cells as an appropriate model system for the analysis of early events in the process of EBV-mediated B-cell immortalization. PMID:15047810

  2. Quantitative Expression and Co-Localization of Wnt Signalling Related Proteins in Feline Squamous Cell Carcinoma

    PubMed Central

    Marote, Georgina; Abramo, Francesca; McKay, Jenny; Thomson, Calum; Beltran, Mariana; Millar, Michael; Priestnall, Simon; Dobson, Jane; Costantino-Casas, Fernando; Petrou, Terry; McGonnell, Imelda M.; Davies, Anthony J.; Weetman, Malcolm; Garden, Oliver A.; Masters, John R.; Thrasivoulou, Christopher; Ahmed, Aamir

    2016-01-01

    Feline oral squamous cell carcinoma (FOSCC) is an aggressive neoplasm in cats. Little is known about the possible molecular mechanisms that may be involved in the initiation, maintenance and progression of FOSCC. Wnt signalling is critical in development and disease, including many mammalian cancers. In this study, we have investigated the expression of Wnt signalling related proteins using quantitative immunohistochemical techniques on tissue arrays. We constructed tissue arrays with 58 individual replicate tissue samples. We tested for the expression of four key Wnt/ß-catenin transcription targets, namely Cyclin D1 (CCND1 or CD1), FRA1, c-Myc and MMP7. All antibodies showed cross reactivity in feline tissue except MMP7. Quantitative immunohistochemical analysis of single proteins (expressed as area fraction / amount of tissue for normal vs tumor, mean ± SE) showed that the expression of CD1 (3.9 ± 0.5 vs 12.2 ± 0.9), FRA1 (5.5 ± 0.6 vs 16.8 ± 1.1) and c-Myc (5.4 ± 0.5 vs 12.5 ± 0.9) was increased in FOSCC tissue by 2.3 to 3 fold compared to normal controls (p<0.0001). By using a multilabel, quantitative fluorophore technique we further investigated if the co-localization of these proteins (all transcription factors) with each other and in the nucleus (stained with 4',6-diamidino-2-phenylindole, DAPI) was altered in FOSCC compared to normal tissue. The global intersection coefficients, a measure of the proximity of two fluorophore labeled entities, showed that there was a significant change (p < 0.01) in the co-localization for all permutations (e.g. CD1/FRA1 etc), except for the nuclear localization of CD1. Our results show that putative targets of Wnt signalling transcription are up-regulated in FOSCC with alterations in the co-localization of these proteins and could serve as a useful marker for the disease. PMID:27559731

  3. Quantitative Expression and Co-Localization of Wnt Signalling Related Proteins in Feline Squamous Cell Carcinoma.

    PubMed

    Giuliano, Antonio; Swift, Rebecca; Arthurs, Callum; Marote, Georgina; Abramo, Francesca; McKay, Jenny; Thomson, Calum; Beltran, Mariana; Millar, Michael; Priestnall, Simon; Dobson, Jane; Costantino-Casas, Fernando; Petrou, Terry; McGonnell, Imelda M; Davies, Anthony J; Weetman, Malcolm; Garden, Oliver A; Masters, John R; Thrasivoulou, Christopher; Ahmed, Aamir

    2016-01-01

    Feline oral squamous cell carcinoma (FOSCC) is an aggressive neoplasm in cats. Little is known about the possible molecular mechanisms that may be involved in the initiation, maintenance and progression of FOSCC. Wnt signalling is critical in development and disease, including many mammalian cancers. In this study, we have investigated the expression of Wnt signalling related proteins using quantitative immunohistochemical techniques on tissue arrays. We constructed tissue arrays with 58 individual replicate tissue samples. We tested for the expression of four key Wnt/ß-catenin transcription targets, namely Cyclin D1 (CCND1 or CD1), FRA1, c-Myc and MMP7. All antibodies showed cross reactivity in feline tissue except MMP7. Quantitative immunohistochemical analysis of single proteins (expressed as area fraction / amount of tissue for normal vs tumor, mean ± SE) showed that the expression of CD1 (3.9 ± 0.5 vs 12.2 ± 0.9), FRA1 (5.5 ± 0.6 vs 16.8 ± 1.1) and c-Myc (5.4 ± 0.5 vs 12.5 ± 0.9) was increased in FOSCC tissue by 2.3 to 3 fold compared to normal controls (p<0.0001). By using a multilabel, quantitative fluorophore technique we further investigated if the co-localization of these proteins (all transcription factors) with each other and in the nucleus (stained with 4',6-diamidino-2-phenylindole, DAPI) was altered in FOSCC compared to normal tissue. The global intersection coefficients, a measure of the proximity of two fluorophore labeled entities, showed that there was a significant change (p < 0.01) in the co-localization for all permutations (e.g. CD1/FRA1 etc), except for the nuclear localization of CD1. Our results show that putative targets of Wnt signalling transcription are up-regulated in FOSCC with alterations in the co-localization of these proteins and could serve as a useful marker for the disease. PMID:27559731

  4. CD34 cells from patients with trisomy 8 myelodysplastic syndrome (MDS) express early apoptotic markers but avoid programmed cell death by up-regulation of antiapoptotic proteins

    PubMed Central

    Pfannes, Loretta; Chen, Gubin; Shah, Simant; Solomou, Elena E.; Barrett, John; Young, Neal S.

    2007-01-01

    CD34 cells from patients with trisomy 8 myelodysplastic syndrome (MDS) are distinguished from other MDS cells and from normal hematopoietic cells by their pronounced expression of apoptotic markers. Paradoxically, trisomy 8 clones can persist in patients with bone marrow failure and expand following immunosuppression. We previously demonstrated up-regulation of c-myc and CD1 by microarray analysis. Here, we confirmed these findings by real-time polymerase chain reaction (PCR), demonstrated up-regulation of survivin, c-myc, and CD1 protein expression, and documented comparable colony formation by annexin+ trisomy 8− CD34+ and annexin− CD34 cells. There were low levels of DNA degradation in annexin+ trisomy 8 CD34 cells, which were comparable with annexin− CD34 cells. Trisomy 8 cells were resistant to apoptosis induced by gamma irradiation. Knock-down of survivin by siRNA resulted in preferential loss of trisomy 8 cells. These results suggest that trisomy 8 cells undergo incomplete apoptosis and are nonetheless capable of colony formation and growth. PMID:17090657

  5. A Novel Secreted Protein, MYR1, Is Central to Toxoplasma’s Manipulation of Host Cells

    PubMed Central

    Franco, Magdalena; Panas, Michael W.; Marino, Nicole D.; Lee, Mei-Chong Wendy; Buchholz, Kerry R.; Kelly, Felice D.; Bednarski, Jeffrey J.; Sleckman, Barry P.; Pourmand, Nader

    2016-01-01

    ABSTRACT The intracellular protozoan Toxoplasma gondii dramatically reprograms the transcriptome of host cells it infects, including substantially up-regulating the host oncogene c-myc. By applying a flow cytometry-based selection to infected mouse cells expressing green fluorescent protein fused to c-Myc (c-Myc–GFP), we isolated mutant tachyzoites defective in this host c-Myc up-regulation. Whole-genome sequencing of three such mutants led to the identification of MYR1 (Myc regulation 1; TGGT1_254470) as essential for c-Myc induction. MYR1 is a secreted protein that requires TgASP5 to be cleaved into two stable portions, both of which are ultimately found within the parasitophorous vacuole and at the parasitophorous vacuole membrane. Deletion of MYR1 revealed that in addition to its requirement for c-Myc up-regulation, the MYR1 protein is needed for the ability of Toxoplasma tachyzoites to modulate several other important host pathways, including those mediated by the dense granule effectors GRA16 and GRA24. This result, combined with its location at the parasitophorous vacuole membrane, suggested that MYR1 might be a component of the machinery that translocates Toxoplasma effectors from the parasitophorous vacuole into the host cytosol. Support for this possibility was obtained by showing that transit of GRA24 to the host nucleus is indeed MYR1-dependent. As predicted by this pleiotropic phenotype, parasites deficient in MYR1 were found to be severely attenuated in a mouse model of infection. We conclude, therefore, that MYR1 is a novel protein that plays a critical role in how Toxoplasma delivers effector proteins to the infected host cell and that this is crucial to virulence. PMID:26838724

  6. Soluble expression and stability enhancement of transcription factors using 30Kc19 cell-penetrating protein.

    PubMed

    Ryu, Jina; Park, Hee Ho; Park, Ju Hyun; Lee, Hong Jai; Rhee, Won Jong; Park, Tai Hyun

    2016-04-01

    Transcription factors have been studied as an important drug candidate. Ever since the successful generation of induced pluripotent stem cells (iPSCs), there has been tremendous interest in reprogramming transcription factors. Because of the safety risks involved in a virus-based approach, many researchers have been trying to deliver transcription factors using nonintegrating materials. Thus, delivery of transcription factors produced as recombinant proteins in E. coli was proposed as an alternative method. However, the low level of soluble expression and instability of such recombinant proteins are potential barriers. We engineered a Bombyx mori 30Kc19 protein as a fusion partner for transcription factors to overcome those problems. We have previously reported that 30Kc19 protein can be produced as a soluble form in E. coli and has a cell-penetrating property and a protein-stabilizing effect. Transcription factors fused with 30Kc19 (Oct4-30Kc19, Sox2-30Kc19, c-Myc-30Kc19, L-Myc-30Kc19, and Klf4-30Kc19) were produced as recombinant proteins. Interestingly, Oct4 and L-Myc were expressed as a soluble form by conjugating with 30Kc19 protein, whereas Oct4 alone and L-Myc alone aggregated. The 30Kc19 protein also enhanced the stability of transcription factors both in vitro and in cells. In addition, 30Kc19-conjugated transcription factors showed rapid delivery into cells and transcriptional activity significantly increased. Overall, 30Kc19 protein conjugation simultaneously enhanced soluble expression, stability, and transcriptional activity of transcription factors. We propose that the conjugation with 30Kc19 protein is a novel approach to solve the technical bottleneck of gene regulation using transcription factors. PMID:26668030

  7. CELLFOOD™ induces apoptosis in human mesothelioma and colorectal cancer cells by modulating p53, c-myc and pAkt signaling pathways

    PubMed Central

    2014-01-01

    Background CELLFOOD™ (CF) is a nutraceutical non-addictive, non-invasive, and completely non-toxic unique proprietary colloidal-ionic formula. Little is known about its effect on cancer cells in solid tumors. The aim of this study was to evaluate the effect that CF has on different cancer cell lines and the mechanism by which the nutraceutical works. Methods The effect of CF on HFF (normal fibroblasts), Met5A (mesothelium), MSTO-211H, NCI-2452, Ist-Mes1, MPP89, Ist-Mes2 (mesothelioma), M14 (melanoma), H1650, H1975 (lung cancer), SKRB3 (breast cancer), and HCT-116 (colorectal cancer) cell growth was tested by cell proliferation and clonogenic assay. Among all of them, MSTO-211 and HCT-116 were analyzed for cell cycle by flow cytometry and western blot. Results All human cancer lines were suppressed on cell growth upon 1:200 CF treatment for 24 and 48 hours. Death was not observed in HFF and Met5A cell lines. Cell cycle analysis showed an increased sub-G1 with reduction of G1 in MSTO-211 and a cell cycle arrest of in G1 in HCT116. Activation of caspase-3 and cleavage of PARP confirmed an apoptotic death for both cell lines. Increased expression levels of p53, p21, and p27, downregulation of c-myc and Bcl-2, and inhibition of Akt activation were also found in CF-treated MSTO-211 and HCT-116 cells. Conclusions These findings ascertained an interaction between p53, c-myc, p21, p27, Bcl-2, PI3K/Akt pathway, and CF-induced apoptosis in MSTO-211H and HCT-116 cells, suggesting that CF acts as an important regulator of cell growth in human cancer cell lines. CF could be a useful nutraceutical intervention for prevention in colon cancer and mesothelioma. PMID:24598211

  8. Definition of a Skp2-c-Myc Pathway to Expand Human Beta-cells

    PubMed Central

    Tiwari, Shiwani; Roel, Chris; Tanwir, Mansoor; Wills, Rachel; Perianayagam, Nidhi; Wang, Peng; Fiaschi-Taesch, Nathalie M.

    2016-01-01

    Type 2 diabetes (T2D) is characterized by insulin resistance and reduced functional β-cell mass. Developmental differences, failure of adaptive expansion and loss of β-cells via β-cell death or de-differentiation have emerged as the possible causes of this reduced β-cell mass. We hypothesized that the proliferative response to mitogens of human β-cells from T2D donors is reduced, and that this might contribute to the development and progression of T2D. Here, we demonstrate that the proliferative response of human β-cells from T2D donors in response to cdk6 and cyclin D3 is indeed dramatically impaired. We show that this is accompanied by increased nuclear abundance of the cell cycle inhibitor, p27kip1. Increasing nuclear abundance of p27kip1 by adenoviral delivery decreases the proliferative response of β-cells from non-diabetic donors, mimicking T2D β-cells. However, while both p27kip1 gene silencing and downregulation by Skp2 overexpression increased similarly the proliferative response of human β-cells, only Skp2 was capable of inducing a significant human β-cell expansion. Skp2 was also able to double the proliferative response of T2D β-cells. These studies define c-Myc as a central Skp2 target for the induction of cell cycle entry, expansion and regeneration of human T2D β-cells. PMID:27380896

  9. Therapeutic targeting of c-Myc in T-cell acute lymphoblastic leukemia, T-ALL.

    PubMed

    Loosveld, Marie; Castellano, Rémy; Gon, Stéphanie; Goubard, Armelle; Crouzet, Thomas; Pouyet, Laurent; Prebet, Thomas; Vey, Norbert; Nadel, Bertrand; Collette, Yves; Payet-Bornet, Dominique

    2014-05-30

    T-ALL patients treated with intensive chemotherapy achieve high rates of remission. However, frequent long-term toxicities and relapses into chemotherapy-refractory tumors constitute major clinical challenges which could be met by targeted therapies. c-MYC is a central oncogene in T-ALL, prompting the exploration of the efficacy of MYC inhibitors such as JQ1 (BET-bromodomain inhibitor), and SAHA (HDAC inhibitor). Using a standardized ex vivo drug screening assay, we show here that JQ1 and SAHA show competitive efficiency compared to inhibitors of proteasome, PI3K/AKT/mTOR and NOTCH pathways, and synergize in combination with Vincristine. We also compared for the first time the in vivo relevance of such associations in mice xenografted with human primary T-ALLs. Our data indicate that although treatments combining JQ1 or SAHA with chemotherapeutic regimens might represent promising developments in T-ALL, combinations will need to be tailored to specific subgroups of responsive patients, the profiles of which still remain to be precisely defined. PMID:24930440

  10. Point Mutations in c-Myc Uncouple Neoplastic Transformation from Multiple Other Phenotypes in Rat Fibroblasts

    PubMed Central

    Graves, J. Anthony; Rothermund, Kristi; Wang, Tao; Qian, Wei; Van Houten, Bennett; Prochownik, Edward V.

    2010-01-01

    Deregulation of c-Myc (Myc) occurs in many cancers. In addition to transforming various cell types, Myc also influences additional transformation-associated cellular phenotypes including proliferation, survival, genomic instability, reactive oxygen species production, and metabolism. Although Myc is wild type in most cancers (wtMyc), it occasionally acquires point mutations in certain lymphomas. Some of these mutations confer a survival advantage despite partially attenuating proliferation and transformation. Here, we have evaluated four naturally-occurring or synthetic point mutations of Myc for their ability to affect these phenotypes, as well as to promote genomic instability, to generate reactive oxygen species and to up-regulate aerobic glycolysis and oxidative phosphorylation. Our findings indicate that many of these phenotypes are genetically and functionally independent of one another and are not necessary for transformation. Specifically, the higher rate of glucose metabolism known to be associated with wtMyc deregulation was found to be independent of transformation. One mutation (Q131R) was greatly impaired for nearly all of the studied Myc phenotypes, yet was able to retain some ability to transform. These findings indicate that, while the Myc phenotypes examined here make additive contributions to transformation, none, with the possible exception of increased reliance on extracellular glutamine for survival, are necessary for achieving this state. PMID:21060841

  11. Cap-independent polysomal association of natural mRNAs encoding c-myc, BiP, and eIF4G conferred by internal ribosome entry sites.

    PubMed Central

    Johannes, G; Sarnow, P

    1998-01-01

    Sequence elements that can function as internal ribosome entry sites (IRES) have been identified in 5' noncoding regions of certain uncapped viral and capped cellular mRNA molecules. However, it has remained largely unknown whether IRES elements are functional when located in their natural capped mRNAs. Therefore, the polysomal association and translation of several IRES-containing cellular mRNAs was tested under conditions that severely inhibited cap-dependent translation, that is, after infection with poliovirus. It was found that several known IRES-containing mRNAs, such as BiP and c-myc, were both associated with the translation apparatus and translated in infected cells when cap-dependent translation of most host-cell mRNAs was blocked, indicating that the IRES elements were functional in their natural mRNAs. Curiously, the mRNAs that encode eukaryotic initiation factor 4GI (eIF4GI) and 4GII (eIF4GII), two proteins with high identity and similar functions in the initiation of cap-dependent translation, were both associated with polysomes in infected cells. The 5'-end sequences of eIF4GI mRNA were isolated from a cDNA expression library and shown to function as an internal ribosome entry site when placed into a dicistronic mRNA. These findings suggest that eIF4G proteins can be synthesized at times when 5' cap-dependent mRNA translation is blocked, supporting the notion that eIF4G proteins are needed in both 5' cap-independent and 5' cap-dependent translational initiation mechanisms. PMID:9848649

  12. Leptospira Protein Expression During Infection

    Technology Transfer Automated Retrieval System (TEKTRAN)

    We are characterizing protein expression in vivo during experimental leptospirosis using immunofluorescence microscopy. Coding regions for several proteins were identified through analysis of Leptospira interrogans serovar Copenhageni and L. borgpetersenii serovar Hardjo genomes. In addition, codi...

  13. Elevated levels of a specific class of nuclear phosphoproteins in cells transformed with v-ras and v-mos oncogenes and by cotransfection with c-myc and polyoma middle T genes.

    PubMed Central

    Giancotti, V; Pani, B; D'Andrea, P; Berlingieri, M T; Di Fiore, P P; Fusco, A; Vecchio, G; Philp, R; Crane-Robinson, C; Nicolas, R H

    1987-01-01

    Transformation of a rat thyroid epithelial cell line (FRTL5-C12) with Kirsten and Harvey murine sarcoma viruses (carrying the ras oncogenes) results in elevated levels of three perchloric acid-soluble nuclear phosphoproteins. These three proteins are also induced to high levels in the PC-C13 thyroid epithelial cell line when transformed by the myeloproliferative sarcoma virus (carrying the v-mos oncogene) and when transformed by transfection with the c-myc proto-oncogene followed by infection with the polyoma leukaemia virus (PyMuLV) carry the polyoma middle T antigen gene. Neither c-myc or PyMuLV alone induced high levels of the three nuclear proteins. Untransformed thyroid fibroblasts have high levels of two of the three proteins and can be transformed by PyMuLV alone resulting in the appearance of the third protein. Transformation with Harvey sarcoma virus also results in the induction of the third protein. The three phosphoproteins have been purified by h.p.l.c. and shown to be related to the HeLa protein HMGI already described. The results of these studies indicate that elevated levels of these HMGI-like proteins are associated with neoplastic transformation and/or with an undifferentiated phenotype. Images Fig. 1. Fig. 2. Fig. 3. Fig. 4. Fig. 5. PMID:2820715

  14. Illegitimate recombinations between c-myc and immunoglobulin loci are remodeled by deletions in mouse plasmacytomas but not in Burkitt's lymphomas.

    PubMed

    Müller, J R; Janz, S; Potter, M

    1995-01-01

    Recombinations between c-myc and immunoglobulin loci are a hallmark of Burkitt's lymphomas and mouse plasmacytomas. Analyzing the fine structure of these illegitimate rearrangements has revealed differences between the recombinations in these two tumors. Recombinations are nearly reciprocal in Burkitt's lymphomas, whereas in most BALB/c plasmacytomas large stretches of c-myc sequences have been deleted. The recombinations detected during preneoplastic development of plasmacytomas, in contrast, have most of the c-myc sequences retained on either one of the translocated chromosomes. We conclude that initial recombination structures are subjected to secondary changes in mouse plasmacytomas. In Burkitt's lymphomas the primary recombination sequence is preserved in tumor cells. PMID:7895518

  15. Perylene and coronene derivatives binding to G-rich promoter oncogene sequences efficiently reduce their expression in cancer cells.

    PubMed

    Micheli, Emanuela; Altieri, Alessandro; Cianni, Lorenzo; Cingolani, Chiara; Iachettini, Sara; Bianco, Armandodoriano; Leonetti, Carlo; Cacchione, Stefano; Biroccio, Annamaria; Franceschin, Marco; Rizzo, Angela

    2016-06-01

    A novel approach to cancer therapeutics is emerging in the field of G-quadruplex (G4) ligands, small molecules designed to stabilize four-stranded structures that can form at telomeres as well as in other genomic sequences, including oncogene promoter sequences, 5'-UTR regions and introns. In this study, we investigated the binding activity of perylene and coronene derivatives PPL3C, CORON and EMICORON to G4 structures formed within the promoter regions of two important cancer-related genes, c-MYC and BCL-2, and their biochemical effects on gene and protein expression. In order to fully characterize the ability of the selected ligands to bind and stabilize the G4 structures originated by the c-MYC and BCL-2 promoter sequences, we performed electrospray ionization mass spectrometry (ESI-MS), Fluorescence Resonance Energy Transfer (FRET) measurements, Circular Dichroism (CD) spectra and polymerase stop assay. Altogether our results showed that the ligands had a high capacity in binding and stabilizing the G4 structures within the c-MYC and BCL-2 promoter sequences in vitro. Notably, when we evaluated by quantitative real-time PCR and western blotting analysis, the effects of treatment with the different G4 ligands on c-MYC and BCL2 expression in a human melanoma cell line, EMICORON appeared the most effective compound in reducing the mRNA and protein levels of both genes. These results encourage to consider EMICORON as a promising example of multimodal class of an antineoplastic drug, affecting different tumor crucial pathways simultaneously: telomere maintenance (as previously described), cell proliferation and apoptosis via down-regulation of both c-MYC and BCL-2 (this paper). PMID:27086081

  16. Nuclear DNA phylogeny of the squirrels (Mammalia: Rodentia) and the evolution of arboreality from c-myc and RAG1.

    PubMed

    Steppan, Scott J; Storz, Brian L; Hoffmann, Robert S

    2004-03-01

    Although the family Sciuridae is large and well known, phylogenetic analyses are scarce. We report on a comprehensive molecular phylogeny for the family. Two nuclear genes (c-myc and RAG1) comprising approximately 4500 bp of data (most in exons) are applied for the first time to rodent phylogenetics. Parsimony, likelihood, and Bayesian analyses of the separate gene regions and combined data reveal five major lineages and refute the conventional elevation of the flying squirrels (Pteromyinae) to subfamily status. Instead, flying squirrels are derived from one of the tree squirrel lineages. C-myc indels corroborate the sequence-based topologies. The common ancestor of extant squirrels appears to have been arboreal, confirming the fossil evidence. The results also reveal an unexpected clade of mostly terrestrial squirrels with African and Holarctic centers of diversity. We present a revised classification of squirrels. Our results demonstrate the phylogenetic utility of relatively slowly evolving nuclear exonic data even for relatively recent clades. PMID:15012949

  17. Involvement of RNA binding proteins AUF1 in mammary gland differentiation

    SciTech Connect

    Nagaoka, Kentaro . E-mail: akenaga@mail.ecc.u-tokyo.ac.jp; Tanaka, Tetsuya; Imakawa, Kazuhiko; Sakai, Senkiti

    2007-08-01

    The expression of many genes, such as {beta}-casein, c-myc, and cyclin D1, is altered by lactogenic hormone stimulation during mammary epithelial cell differentiation. Here, we demonstrate that post-transcriptional regulation plays an important role to establish gene expression required to initiate milk production as well as transcriptional control. AUF1 protein, a member of the AU-rich element (ARE)-binding protein family, plays a role in ARE-mRNA turnover by regulating mRNA stability and/or translational control. Cytoplasmic localization of AUF1 protein is critically linked to function. We show that as the mammary gland differentiates, AUF1 protein moves from the cytoplasm to the nucleus. Moreover, in mammary gland epithelial cells (HC11), stimulation by lactogenic hormone decreased cytoplasmic and increased nuclear AUF1 levels. Direct binding of AUF1 protein was observed on c-myc mRNA, but not {beta}-casein or cyclin D1 mRNA. AUF1 downregulation in HC11 cells increased the expression of {beta}-casein mRNA and decreased the expression of c-myc mRNA by lactogenic hormone. Conversely, overexpression of AUF1 inhibited these effects of lactogenic hormone stimulation in HC11 cells. These results suggest that AUF1 participates in mammary gland differentiation processes under the control of lactogenic hormone signals.

  18. C-Myc Induced Compensated Cardiac Hypertrophy Increases Free Fatty Acid Utilization for the Citric Acid Cycle

    SciTech Connect

    Olson, Aaron; Ledee, Dolena; Iwamoto, Kate; Kajimoto, Masaki; O'Kelly-Priddy, Colleen M.; Isern, Nancy G.; Portman, Michael A.

    2013-02-01

    The protooncogene C-Myc (Myc) regulates cardiac hypertrophy. Myc promotes compensated cardiac function, suggesting that the operative mechanisms differ from those leading to heart failure. Myc regulation of substrate metabolism is a reasonable target, as Myc alters metabolism in other tissues. We hypothesize that Myc-induced shifts in substrate utilization signal and promote compensated hypertrophy. We used cardiac specific Myc-inducible C57/BL6 male mice between 4-6 months old that develop hypertrophy with tamoxifen (tam). Isolated working hearts and 13Carbon (13C )-NMR were used to measure function and fractional contributions (Fc) to the citric acid cycle by using perfusate containing 13C-labeled free fatty acids, acetoacetate, lactate, unlabeled glucose and insulin. Studies were performed at pre-hypertrophy (3-days tam, 3dMyc), established hypertrophy (7-days tam, 7dMyc) or vehicle control (cont). Non-transgenic siblings (NTG) received 7-days tam or vehicle to assess drug effect. Hypertrophy was confirmed by echocardiograms and heart weights. Western blots were performed on key metabolic enzymes. Hypertrophy occurred in 7dMyc only. Cardiac function did not differ between groups. Tam alone did not affect substrate contribution in NTG. Substrate utilization was not significantly altered in 3dMyc versus cont. The free fatty acid FC was significantly greater in 7dMyc vs cont with decreased unlabeled Fc, which is predominately exogenous glucose. Free fatty acid flux to the citric acid cycle increased while lactate flux was diminished in 7dMyc compared to cont. Total protein levels of a panel of key metabolic enzymes were unchanged; however total protein O-GlcNAcylation was increased in 7dMyc. Substrate utilization changes did not precede hypertrophy; therefore they are not the primary signal for cardiac growth in this model. Free fatty acid utilization and oxidation increase at established hypertrophy. Understanding the mechanisms whereby this change maintained

  19. Indole-3-carbinol induces cMYC and IAP-family downmodulation and promotes apoptosis of Epstein-Barr virus (EBV)-positive but not of EBV-negative Burkitt's lymphoma cell lines.

    PubMed

    Perez-Chacon, Gema; de Los Rios, Cristobal; Zapata, Juan M

    2014-11-01

    Indole-3-carbinol (I3C) is a natural product found in broadly consumed plants of the Brassica genus, such as broccoli, cabbage, and cauliflower, which exhibits anti-tumor effects through poorly defined mechanisms. I3C can be orally administered and clinical trials have demonstrated that I3C and derivatives are safe in humans. In this study we show that I3C efficiently induces apoptosis in cell lines derived from EBV-positive Burkitt's lymphomas (virus latency I/II), while it does not have any cytotoxic activity against EBV-negative Burkitt's lymphomas and immortalized EBV-infected lymphoblastoid cell lines (virus latency III). The effect of I3C in EBV-positive Burkitt's lymphoma is very specific, since only I3C and its C6-methylated derivative, but not other 3-substituted indoles, have an effect on cell viability. I3C treatment caused apoptosis characterized by loss of mitochondria membrane potential and caspase activation. I3C alters the expression of proteins involved in the control of apoptosis and transcription regulation in EBV-positive Burkitt's lymphoma cell lines. Among those, cMYC, cIAP1/2 and XIAP downmodulation at mRNA and protein level precede apoptosis induction, thus suggesting a role in I3C cytotoxicity. We also showed that I3C and, more particularly, its condensation dimer 3,3'-diindolylmethane (DIM) prolonged survival and reduced tumor burden of mice xenotransplanted with EBV-positive Burkitt's lymphoma Daudi cells. In summary these results, together with previous reports from clinical trials indicating the lack of toxicity in humans of I3C and derivatives, support the use of these compounds as a new therapeutic approach for treating patients with endemic (EBV-positive) Burkitt's lymphoma. PMID:25180456

  20. FOXM1c transactivates the human c-myc promoter directly via the two TATA boxes P1 and P2.

    PubMed

    Wierstra, Inken; Alves, Jürgen

    2006-10-01

    FOXM1c transactivates the c-myc promoter via the P1 and P2 TATA boxes using a new mechanism. Whereas the P1 TATA box TATAATGC requires its sequence context to be FOXM1c responsive, the P2 TATA box TATAAAAG alone is sufficient to confer FOXM1c responsiveness to any minimal promoter. FOXM1c transactivates by binding to the TATA box as well as directly to TATA-binding protein, transcription factor IIB and transcription factor IIA. This new transactivation mechanism is clearly distinguished from the function of FOXM1c as a conventional transcription factor. The central domain of FOXM1c functions as an essential domain for activation via the TATA box, but as an inhibitory domain (retinoblastoma protein-independent transrepression domain and retinoblastoma protein-recruiting negative regulatory domain) for transactivation via conventional FOXM1c-binding sites. Each promoter with the P2 TATA box TATAAAAG is postulated to be transactivated by FOXM1c. This was demonstrated for the promoters of c-fos, hsp70 and histone H2B/a. A database search revealed almost 300 probable FOXM1c target genes, many of which function in proliferation and tumorigenesis. Accordingly, dominant-negative FOXM1c proteins reduced cell growth approximately threefold, demonstrating a proliferation-stimulating function for wild-type FOXM1c. PMID:16965535

  1. Signaling Pathway of GP88 (Progranulin) in Breast Cancer Cells: Upregulation and Phosphorylation of c-myc by GP88/Progranulin in Her2-Overexpressing Breast Cancer Cells

    PubMed Central

    Kim, Wes E.; Yue, Binbin; Serrero, Ginette

    2015-01-01

    Her2 is a receptor tyrosine kinase overexpressed in 25% of breast tumors. We have shown that the 88 kDa autocrine growth and survival factor GP88 (progranulin) stimulated Her2 phosphorylation and proliferation and conferred Herceptin resistance in Her2-overexpressing cells. Herein, we report that GP88 stimulates c-myc phosphorylation and upregulates c-myc levels in Her2-overexpressing cells. c-myc phosphorylation and upregulation by GP88 were not observed in non-Her2-overexpressing breast cancer cells. c-myc activation was inhibited upon treatment with ERK, PI3 kinase, and c-src pathway inhibitors, U0126, LY294002, and PP2. GP88 also stimulated c-src phosphorylation, a known upstream regulator of c-myc. Thus, we describe here a signaling pathway for GP88 in Her2-overexpressing cells, with GP88 stimulating Src phosphorylation, followed by phosphorylation and upregulation of c-myc. These data would suggest that targeting GP88 could provide a novel treatment approach in breast cancer. PMID:27168723

  2. Reducing VDAC1 expression induces a non-apoptotic role for pro-apoptotic proteins in cancer cell differentiation.

    PubMed

    Arif, Tasleem; Krelin, Yakov; Shoshan-Barmatz, Varda

    2016-08-01

    Proteins initially identified as essential for apoptosis also mediate a wide range of non-apoptotic functions that include cell cycle progression, differentiation and metabolism. As this phenomenon was mostly reported with non-cancer cells, we considered non-conventional roles for the apoptotic machinery in the cancer setting. We found that treating glioblastoma (GBM) tumors with siRNA against VDAC1, a mitochondrial protein found at the crossroads of metabolic and survival pathways and involved in apoptosis, inhibited tumor growth while leading to differentiation of tumor cells into neuronal-like cells, as reflected in the expression of specific markers. Although VDAC1 depletion did not induce apoptosis, the expression levels of several pro-apoptotic regulatory proteins were changed. Specifically, VDAC1 deletion led to up-regulation of caspases, p53, cytochrome c, and down-regulation of SMAC/Diablo, AIF and TSPO. The down-regulated group was highly expressed in U-87MG xenografts, as well as in GBMs from human patients. We also showed that the rewired cancer-cell metabolism resulting from VDAC1 depletion reinforced cell growth arrest and differentiation via alterations in the transcription factors p53, c-Myc, HIF-1α and NF-κB. The decrease in c-Myc, HIF-1α and NF-κB levels was in accord with reduced cell proliferation, whereas increased p53 expression promoted differentiation. Thus, upon metabolic re-programing induced by VDAC1 depletion, the levels of pro-apoptotic proteins associated with cell growth decreased, while those connected to cell differentiation increased, converting GBM cells into astrocyte- and neuron-like cells. The results reveal that in tumors, pro-apoptotic proteins can perform non-apoptotic functions, acting as regulators of cell growth and differentiation, making these molecules potential new targets for cancer therapy. This article is part of a Special Issue entitled 'EBEC 2016: 19th European Bioenergetics Conference, Riva del Garda, Italy

  3. Binding studies using Pichia pastoris expressed human aryl hydrocarbon receptor and aryl hydrocarbon receptor nuclear translocator proteins.

    PubMed

    Zheng, Yujuan; Xie, Jinghang; Huang, Xin; Dong, Jin; Park, Miki S; Chan, William K

    2016-06-01

    The aryl hydrocarbon receptor (AHR) is a transcription factor which activates gene transcription by binding to its corresponding enhancer as the heterodimer, which is consisted of AHR and the aryl hydrocarbon receptor nuclear translocator (ARNT). Human AHR can be rather difficult to study, when compared among the AHR of other species, since it is relatively unstable and less sensitive to some ligands in vitro. Overexpression of human AHR has been limited to the baculovirus expression, which is costly and tedious due to the need of repetitive baculovirus production. Here we explored whether we could generate abundant amounts of human AHR and ARNT in a better overexpression system for functional study. We observed that human AHR and ARNT can be expressed in Pichia pastoris with yields that are comparable to the baculovirus system only if their cDNAs are optimized for Pichia expression. Fusion with a c-myc tag at their C-termini seems to increase the expression yield. These Pichia expressed proteins can effectively heterodimerize and form the ternary AHR/ARNT/enhancer complex in the presence of β-naphthoflavone or kynurenine. Limited proteolysis using thermolysin can be used to study the heterodimerization of these human AHR and ARNT proteins. PMID:26923060

  4. Genomic structure and precise mapping of a thymic regulatory region on mouse chromosome 17 revealed by a c-myc transgene insertion

    SciTech Connect

    Lavenu, A.; Morello, D.; Roland, J.

    1996-06-15

    In one transgenic strain harboring a human c-myc proto-oncogene construct, the transgene was actively and exclusively expressed in the thymus, where it contributed to the development of lymphoma that corresponded to CD4{sup +}CD8{sup +} cells. Here, we have pursued the analysis of transgene expression in healthy transgenic mice and show that transgene activation occurs in the thymus 3 days before birth, at a time when CD4{sup +}CD8{sup +} lymphocytes emerge. In the adult, its expression is restricted to the CD4{sup +}CD8{sup +} cells. The region flanking the transgene insertion site was isolated and made it possible to map the preintegration locus, hereafter called Tsil (for thymus-specific integration locus) on chromosome 17 between D17Rp11e and Ras12-3. A YAC that contains both Tsil and the Pim2 locus, previously shown to be involved in progression of T-cell lymphoma, was isolated. Analysis of Tsil offers a unique opportunity to identify a regulatory region or a gene that might play an important role in T-cell maturation. 41 refs., 5 figs., 2 tabs.

  5. Protein expression of matrix metalloproteinase (MMP-1, -2, -3, -9 and -14) in Ewing family tumors and medulloblastomas of pediatric patients

    PubMed Central

    Mateo, Elvis Cueva; Motta, Fabio José Nascimento; Queiroz, Rosane Gomes de Paula; Scrideli, Carlos Alberto; Tone, Luiz Gonzaga

    2012-01-01

    The matrix metalloproteinases (MMP) are endopeptidases performing proteolytic functions in the extracellular matrix and their overexpression has been suggested to be a characteristic of malignant tumors. Molecular changes such as the presence of chimeric protein Ewing’s sarcoma protein-friend leukemia virus integration 1 (EWS-FLI1) in the Ewing family of tumors (EFT) and the oncogenes C-ERBB-2, N-MYC, C-MYC in medulloblastoma (MB) promote the overexpression of MMP. In the present study, protein expression of MMP-1, -2, -3, -9 and -14 was qualitatively evaluated in 17 EFT and MB samples of children and adolescent by western blotting and optical densitometry, and the level of gene expression of some MMPs was determined by real-time quantitative polymerase chain reaction. Five MB samples (45.4%) presented expression of the five MMPs and six samples (54.6%) presented expression of at least one of them. Four EFT samples (66.6%) presented expression of MMP-2, -9 and -14, and two samples (33.4%) presented expression of at least one of these MMPs, whereas the presence of MMP-1 and -3 was not observed. Gene analysis showed that MMP-2 had a high expression in MB, while the expression of MMP-9 and MMP-14 was higher in EFT. It has been established that the expression of the MMPs might be related to a complex pathway of gene regulation.

  6. Specific Stabilization of c-MYC and c-KIT G-Quadruplex DNA Structures by Indolylmethyleneindanone Scaffolds.

    PubMed

    Diveshkumar, K V; Sakrikar, Saaz; Rosu, Frédéric; Harikrishna, S; Gabelica, Valérie; Pradeepkumar, P I

    2016-06-28

    Stabilization of G-quadruplex DNA structures by small molecules has emerged as a promising strategy for the development of anticancer drugs. Since G-quadruplex structures can adopt various topologies, attaining specific stabilization of a G-quadruplex topology to halt a particular biological process is daunting. To achieve this, we have designed and synthesized simple structural scaffolds based on an indolylmethyleneindanone pharmacophore, which can specifically stabilize the parallel topology of promoter quadruplex DNAs (c-MYC, c-KIT1, and c-KIT2), when compared to various topologies of telomeric and duplex DNAs. The lead ligands (InEt2 and InPr2) are water-soluble and meet a number of desirable criteria for a small molecule drug. Highly specific induction and stabilization of the c-MYC and c-KIT quadruplex DNAs (ΔT1/2 up to 24 °C) over telomeric and duplex DNAs (ΔT1/2 ∼ 3.2 °C) by these ligands were further validated by isothermal titration calorimetry and electrospray ionization mass spectrometry experiments (Ka ∼ 10(5) to 10(6) M(-1)). Low IC50 (∼2 μM) values were emerged for these ligands from a Taq DNA polymerase stop assay with the c-MYC quadruplex forming template, whereas the telomeric DNA template showed IC50 values >120 μM. Molecular modeling and dynamics studies demonstrated the 5'- and 3'-end stacking modes for these ligands. Overall, these results demonstrate that among the >1000 quadruplex stabilizing ligands reported so far, the indolylmethyleneindanone scaffolds stand out in terms of target specificity and structural simplicity and therefore offer a new paradigm in topology specific G-quadruplex targeting for potential therapeutic and diagnostic applications. PMID:27226253

  7. Three-dimensional imaging of the metabolic state of c-MYC-induced mammary tumor with the cryo-imager

    NASA Astrophysics Data System (ADS)

    Zhang, Zhihong; Liu, Qian; Luo, Qingming; Zhang, Min Z.; Blessington, Dana M.; Zhou, Lanlan; Chodosh, Lewis A.; Zheng, Gang; Chance, Britton

    2003-07-01

    This study imaged the metabolic state of a growing tumor and the relationship between energy metabolism and the ability of glucose uptake in whole tumor tissue with cryo-imaging at 77° K. A MTB/TOM mouse model, bearing c-MYC-induced mammary tumor, was very rapidly freeze-trapped 2 hrs post Pyro-2DG injection. The fluorescence signals of oxidized flavoprotein (Fp), reduced pyridine nucleotide (PN), pyro-2DG, and the reflection signal of deoxy-hemoglobin were imaged every 100 μm from the top surface to the bottom of the tumor sequentially, 9 sections in total. Each of the four signals was constructed into 3D images with Amira software. Both Fp and PN signals could be detected in the growing tumor regions, and a higher reduction state where was shown in the ratio images. The necrotic tumor regions displayed a very strong Fp signal and weak PN signal. In the bloody extravasation regions, Fp and PN signals were observably diminished. Therefore, the regions of high growth and necrosis in the tumor could be determined according to the Fp and PN signals. The content of deoxy-hemoglobin (Hb) in the tumor was positively correlated with the reduced PN signal. Pyro-2DG signal was only evident in the growing condition region in the tumor. Normalized 3D cross-correlation showed that Pyro-2DG signal was similar to the redox ratio. The results indicated that glucose uptake in the tumor was consistent with the redox state of the tumor. And both Pyro-2DG and mitochondrial NADH fluorescence showed bimodal histograms suggesting that the two population of c-MYC induced mammary tumor, one of which could be controlled by c-MYC transgene.

  8. Generation of liver-specific TGF-α/c-Myc-overexpressing porcine induced pluripotent stem-like cells and blastocyst formation using nuclear transfer.

    PubMed

    Park, Kyung-Mee; Lee, Joohyeong; Hussein, Kamal Hany; Hong, Seok-Ho; Yang, Se-Ran; Lee, Eunsong; Woo, Heung-Myong

    2016-05-01

    Transgenic porcine induced pluripotent stem (iPS) cells are attractive cell sources for the development of genetically engineered pig models, because they can be expanded without senescence and have the potential for multiple gene manipulation. They are also useful cell sources for disease modeling and treatment. However, the generation of transgenic porcine iPS cells is rare, and their embryonic development after nuclear transfer (NT) has not yet been reported. We report here the generation of liver-specific oncogenes (TGF-α/c-Myc)-overexpressing porcine iPS (T/M iPS)-like cells. They expressed stem cell characteristics and were differentiated into hepatocyte-like cells that express oncogenes. We also confirmed that NT embryos derived from T/M iPS-like cells successfully developed blastocysts in vitro. As an initial approach toward porcine transgenic iPS cell generation and their developmental competence after NT, this study provides foundations for the efficient generation of genetically modified porcine iPS cells and animal models. PMID:26725870

  9. 4EBP1/c-MYC/PUMA and NF-κB/EGR1/BIM pathways underlie cytotoxicity of mTOR dual inhibitors in malignant lymphoid cells.

    PubMed

    Yun, Seongseok; Vincelette, Nicole D; Knorr, Katherine L B; Almada, Luciana L; Schneider, Paula A; Peterson, Kevin L; Flatten, Karen S; Dai, Haiming; Pratz, Keith W; Hess, Allan D; Smith, B Douglas; Karp, Judith E; Hendrickson, Andrea E Wahner; Fernandez-Zapico, Martin E; Kaufmann, Scott H

    2016-06-01

    The mammalian target of rapamycin (mTOR), a kinase that regulates proliferation and apoptosis, has been extensively evaluated as a therapeutic target in multiple malignancies. Rapamycin analogs, which partially inhibit mTOR complex 1 (mTORC1), exhibit immunosuppressive and limited antitumor activity, but sometimes activate survival pathways through feedback mechanisms involving mTORC2. Thus, attention has turned to agents targeting both mTOR complexes by binding the mTOR active site. Here we show that disruption of either mTOR-containing complex is toxic to acute lymphocytic leukemia (ALL) cells and identify 2 previously unrecognized pathways leading to this cell death. Inhibition of mTORC1-mediated 4EBP1 phosphorylation leads to decreased expression of c-MYC and subsequent upregulation of the proapoptotic BCL2 family member PUMA, whereas inhibition of mTORC2 results in nuclear factor-κB-mediated expression of the Early Growth Response 1 (EGR1) gene, which encodes a transcription factor that binds and transactivates the proapoptotic BCL2L11 locus encoding BIM. Importantly, 1 or both pathways contribute to death of malignant lymphoid cells after treatment with dual mTORC1/mTORC2 inhibitors. Collectively, these observations not only provide new insight into the survival roles of mTOR in lymphoid malignancies, but also identify alterations that potentially modulate the action of mTOR dual inhibitors in ALL. PMID:26917778

  10. Generation of liver-specific TGF-α/c-Myc-overexpressing porcine induced pluripotent stem-like cells and blastocyst formation using nuclear transfer

    PubMed Central

    PARK, Kyung-Mee; LEE, Joohyeong; HUSSEIN, Kamal Hany; HONG, Seok-Ho; YANG, Se-Ran; LEE, Eunsong; WOO, Heung-Myong

    2015-01-01

    Transgenic porcine induced pluripotent stem (iPS) cells are attractive cell sources for the development of genetically engineered pig models, because they can be expanded without senescence and have the potential for multiple gene manipulation. They are also useful cell sources for disease modeling and treatment. However, the generation of transgenic porcine iPS cells is rare, and their embryonic development after nuclear transfer (NT) has not yet been reported. We report here the generation of liver-specific oncogenes (TGF-α/c-Myc)-overexpressing porcine iPS (T/M iPS)-like cells. They expressed stem cell characteristics and were differentiated into hepatocyte-like cells that express oncogenes. We also confirmed that NT embryos derived from T/M iPS-like cells successfully developed blastocysts in vitro. As an initial approach toward porcine transgenic iPS cell generation and their developmental competence after NT, this study provides foundations for the efficient generation of genetically modified porcine iPS cells and animal models. PMID:26725870

  11. Sleeping Beauty transposon system harboring HRAS, c-Myc and shp53 induces sarcomatoid carcinomas in mouse skin.

    PubMed

    Jung, Sunyoung; Ro, Simon Weonsang; Jung, Geunyoung; Ju, Hye-Lim; Yu, Eun-Sil; Son, Woo-Chan

    2013-04-01

    The Sleeping Beauty transposon system is used as a tool for insertional mutagenesis and oncogenesis. However, little is known about the exact histological phenotype of the tumors induced. Thus, we used immunohistochemical markers to enable histological identification of the type of tumor induced by subcutaneous injection of the HRAS, c-Myc and shp53 oncogenes in female C57BL/6 mice. The tumor was removed when it reached 100 mm3 in volume. Subsequently, we used 13 immunohistochemical markers to histologically identify the tumor type. The results suggested that the morphology of the tumor was similar to that of sarcomatoid carcinoma. PMID:23380875

  12. Sleeping Beauty transposon system harboring HRAS, c-Myc and shp53 induces sarcomatoid carcinomas in mouse skin

    PubMed Central

    JUNG, SUNYOUNG; RO, SIMON WEONSANG; JUNG, GEUNYOUNG; JU, HYE-LIM; YU, EUN-SIL; SON, WOO-CHAN

    2013-01-01

    The Sleeping Beauty transposon system is used as a tool for insertional mutagenesis and oncogenesis. However, little is known about the exact histological phenotype of the tumors induced. Thus, we used immunohistochemical markers to enable histological identification of the type of tumor induced by subcutaneous injection of the HRAS, c-Myc and shp53 oncogenes in female C57BL/6 mice. The tumor was removed when it reached 100 mm3 in volume. Subsequently, we used 13 immunohistochemical markers to histologically identify the tumor type. The results suggested that the morphology of the tumor was similar to that of sarcomatoid carcinoma. PMID:23380875

  13. Kaiso is a key regulator of spleen germinal center formation by repressing Bcl6 expression in splenocytes

    SciTech Connect

    Koh, Dong-In; Yoon, Jae-Hyeon; Kim, Min-Kyeong; An, Haemin; Kim, Min-Young; Hur, Man-Wook

    2013-12-13

    Highlights: •Knockout of Kaiso results in concordant high expression of Bcl6 and c-Myc in spleen. •Kaiso binds the Bcl6 promoter and represses Bcl6 transcription by recruiting NCoR. •Upregulated Bcl6 increases splenocyte proliferation and causes large diffused GC. •Cell cycle-inhibition genes such as Cdkn1b and Cdkn1a are repressed by Bcl6. -- Abstract: Kaiso was previously described as a methylated DNA-binding protein and a transcription repressor interacting with the corepressor protein complex NCoR. In the current study, we show that generation-3 Kaiso knockout mice show a phenotype of splenomegaly and large diffused germinal centers (GC). In the spleens of Kaiso knockout mice, Bcl6 (a transcriptional repressor that plays a critical role in GC development in spleen) and c-Myc were highly expressed, while the cell cycle arrest genes p27 (CDKN1B), p21 (CDKN1A) and Gadd45a were downregulated. Chromatin immunoprecipitation (ChIP) and transcription assays suggested that Kaiso represses Bcl6 expression, and in Kaiso knockout mice, derepressed Bcl6 increased cell proliferation by suppressing p27 (CDKN1B), p21 (CDKN1A) and Gadd45a, while upregulating the oncogene c-Myc. Further evidence for Kaiso regulation of splenomegaly was provided by B lymphocyte Ramos cells, in which ectopic KAISO repressed BCL6 and c-MYC expression, while concomitantly increasing the expression of the cell cycle arrestors p21, p27 and Gadd45a. In summary, derepressed Bcl6 expression may be responsible for increases in GC cell proliferation and splenomegaly of Kaiso knockout mice.

  14. The Interaction of Telomeric DNA and C-myc22 G-Quadruplex with 11 Natural Alkaloids

    PubMed Central

    Ji, Xiaohui; Sun, Hongxia; Zhou, Huaxi; Xiang, Junfeng

    2012-01-01

    Telomeric DNA and C-myc22 are DNA G-quadruplex (G4)-forming sequences associated with tumorigenesis. Ligands that can facilitate the formation and increase the stabilization of G4 can halt tumor cell proliferation and have been regarded as potential anti-cancer drugs. In the present study, we have investigated the interaction of 11 natural alkaloids with G4 formed by telomeric DNA and C-myc22 sequences. Our results indicated that sanguinarine (San), palmatine (Pal), and berberine (Beb) of the first series (S1) can induce the formation of G4 as well as increase the stabilization ability. Daurisoline (S2-1), O-methyldauricine (S2-2), O-diacetyldaurisoline (S2-3), daurinoline (S2-4), dauricinoline (S2-5), N,N′-dimethyldauricine iodide (S2-6), and N,N′-dimethyldaurisoline iodide (S2-7) of the second series (S2) showed similar stabilization ability. We found that unsaturated ring C, N+ positively charged centers, and conjugated aromatic rings are key factors to increase the stabilization ability of S1, and we gave some advice on structure modification to S2 through structure-activity study. Besides, we found San and Pal to be cell cycle blocker in G1. San was speculated to bind to G4 through intercalation or end stacking. PMID:22480315

  15. 5-aza-2′-deoxycytidine-mediated c-myc Down-regulation Triggers Telomere-dependent Senescence by Regulating Human Telomerase Reverse Transcriptase in Chronic Myeloid Leukemia1

    PubMed Central

    Grandjenette, Cindy; Schnekenburger, Michael; Karius, Tommy; Ghelfi, Jenny; Gaigneaux, Anthoula; Henry, Estelle; Dicato, Mario; Diederich, Marc

    2014-01-01

    Increased proliferation rates as well as resistance to apoptosis are considered major obstacles for the treatment of patients with chronic myelogenous leukemia (CML), thus highlighting the need for novel therapeutic approaches. Since senescence has been recognized as a physiological barrier against tumorigenesis, senescence-based therapy could represent a new strategy against CML. DNA demethylating agent 5-aza-2′-deoxycytidine (DAC) was reported to induce cellular senescence but underlying mechanisms remain to be elucidated. Here, we report that exposure to DAC triggers senescence in chronic leukemia cell lines as evidenced by increased senescence-associated β-galactosidase activity and lysosomal mass, accompanied by an up-regulation of cell cycle-related genes. We provide evidence that DAC is able to decrease telomere length, to reduce telomerase activity and to decrease human telomerase reverse transcriptase (hTERT) expression through decreased binding of c-myc to the hTERT promoter. Altogether, our results reveal the role of c-myc in telomere-dependent DAC-induced senescence and therefore provide new clues for improving chronic human leukemia treatments. PMID:24970385

  16. Overexpression of v-abl uniquely cooperates with c-myc dysregulation in induction of plasma cell tumors, bypassing the need for T-lymphocytic help and overcoming T-lymphocytic interference.

    PubMed

    Weissinger, E M; Byrd, L G; Henderson, D W; Mushinski, J F

    1996-07-01

    We have investigated the effects of T lymphocytes on induction of mouse plasma cell tumors. We show that ABL-MYC, a plasmacytomagenic retrovirus that constitutively expresses v-abl and c-myc, is able to induce plasmacytomas in 100% of athymic BALB/c mice, with or without intraperitoneal pristane pretreatment. Other induction regimens are ineffective under these conditions, indicating that the combination of v-abl and c-myc oncogenes is uniquely able to transform plasma cells in mice that are deficient in T lymphocytes. Furthermore, in the absence of pristane, ABL-MYC-infected athymic congenics developed plasmacytomas in half the time required for euthymic BALB/c mice, suggesting that T lymphocytes can have a negative effect and can retard, but not totally inhibit, the outgrowth of plasmacytomas. This phenomenon could not be appreciated in other regimens of plasmacytoma induction, because only ABL-MYC is sufficient to induce plasmacytomas in athymic mice or in euthymic mice in the absence of pristane pretreatment. PMID:8690515

  17. miR-34a induces cellular senescence via modulation of telomerase activity in human hepatocellular carcinoma by targeting FoxM1/c-Myc pathway

    PubMed Central

    Xu, Xinsen; Chen, Wei; Miao, Runchen; Zhou, Yanyan; Wang, Zhixin; Zhang, Lingqiang; Wan, Yong; Dong, Yafeng; Qu, Kai; Liu, Chang

    2015-01-01

    Increasing evidence suggests that miRNAs can act as either tumor suppressors or oncogenes in carcinogenesis. In the present study, we identified the role of miR-34a in regulating telomerase activity, with subsequent effect on cellular senescence and viability. We found the higher expression of miR-34a was significantly correlated with the advanced clinicopathologic parameters in hepatocellular carcinoma. Furthermore, tumor tissues of 75 HCC patients demonstrated an inverse correlation between the miR-34a level and telomere indices (telomere length and telomerase activity). Transient introduction of miR-34a into HCC cell lines inhibited the telomerase activity and telomere length, which induced senescence-like phenotypes and affected cellular viability. We discovered that miR-34a potently targeted c-Myc and FoxM1, both of which were involved in the activation of telomerase reverse transcriptase (hTERT) transcription, essential for the sustaining activity of telomerase to avoid senescence. Taken together, our results demonstrate that miR-34a functions as a potent tumor suppressor through the modulation of telomere pathway in cellular senescence. PMID:25686834

  18. miR-34a induces cellular senescence via modulation of telomerase activity in human hepatocellular carcinoma by targeting FoxM1/c-Myc pathway.

    PubMed

    Xu, Xinsen; Chen, Wei; Miao, Runchen; Zhou, Yanyan; Wang, Zhixin; Zhang, Lingqiang; Wan, Yong; Dong, Yafeng; Qu, Kai; Liu, Chang

    2015-02-28

    Increasing evidence suggests that miRNAs can act as either tumor suppressors or oncogenes in carcinogenesis. In the present study, we identified the role of miR-34a in regulating telomerase activity, with subsequent effect on cellular senescence and viability. We found the higher expression of miR-34a was significantly correlated with the advanced clinicopathologic parameters in hepatocellular carcinoma. Furthermore, tumor tissues of 75 HCC patients demonstrated an inverse correlation between the miR-34a level and telomere indices (telomere length and telomerase activity). Transient introduction of miR-34a into HCC cell lines inhibited the telomerase activity and telomere length, which induced senescence-like phenotypes and affected cellular viability. We discovered that miR-34a potently targeted c-Myc and FoxM1, both of which were involved in the activation of telomerase reverse transcriptase (hTERT) transcription, essential for the sustaining activity of telomerase to avoid senescence. Taken together, our results demonstrate that miR-34a functions as a potent tumor suppressor through the modulation of telomere pathway in cellular senescence. PMID:25686834

  19. Protein identification and Peptide expression resolver: harmonizing protein identification with protein expression data.

    PubMed

    Kearney, Paul; Butler, Heather; Eng, Kevin; Hugo, Patrice

    2008-01-01

    Proteomic discovery platforms generate both peptide expression information and protein identification information. Peptide expression data are used to determine which peptides are differentially expressed between study cohorts, and then these peptides are targeted for protein identification. In this paper, we demonstrate that peptide expression information is also a powerful tool for enhancing confidence in protein identification results. Specifically, we evaluate the following hypothesis: tryptic peptides originating from the same protein have similar expression profiles across samples in the discovery study. Evidence supporting this hypothesis is provided. This hypothesis is integrated into a protein identification tool, PIPER (Protein Identification and Peptide Expression Resolver), that reduces erroneous protein identifications below 5%. PIPER's utility is illustrated by application to a 72-sample biomarker discovery study where it is demonstrated that false positive protein identifications can be reduced below 5%. Consequently, it is recommended that PIPER methodology be incorporated into proteomic studies where both protein expression and identification data are collected. PMID:18062667

  20. mTOR complex 2 controls glycolytic metabolism in glioblastoma through FoxO acetylation and upregulation of c-Myc.

    PubMed

    Masui, Kenta; Tanaka, Kazuhiro; Akhavan, David; Babic, Ivan; Gini, Beatrice; Matsutani, Tomoo; Iwanami, Akio; Liu, Feng; Villa, Genaro R; Gu, Yuchao; Campos, Carl; Zhu, Shaojun; Yang, Huijun; Yong, William H; Cloughesy, Timothy F; Mellinghoff, Ingo K; Cavenee, Webster K; Shaw, Reuben J; Mischel, Paul S

    2013-11-01

    Aerobic glycolysis (the Warburg effect) is a core hallmark of cancer, but the molecular mechanisms underlying it remain unclear. Here, we identify an unexpected central role for mTORC2 in cancer metabolic reprogramming where it controls glycolytic metabolism by ultimately regulating the cellular level of c-Myc. We show that mTORC2 promotes inactivating phosphorylation of class IIa histone deacetylases, which leads to the acetylation of FoxO1 and FoxO3, and this in turn releases c-Myc from a suppressive miR-34c-dependent network. These central features of activated mTORC2 signaling, acetylated FoxO, and c-Myc levels are highly intercorrelated in clinical samples and with shorter survival of GBM patients. These results identify a specific, Akt-independent role for mTORC2 in regulating glycolytic metabolism in cancer. PMID:24140020

  1. Identification and characterization of a cell cycle and apoptosis regulatory protein-1 as a novel mediator of apoptosis signaling by retinoid CD437.

    PubMed

    Rishi, Arun K; Zhang, Liyue; Boyanapalli, Madanamohan; Wali, Anil; Mohammad, Ramzi M; Yu, Yingjie; Fontana, Joseph A; Hatfield, James S; Dawson, Marcia I; Majumdar, Adhip P N; Reichert, Uwe

    2003-08-29

    CD437, a novel retinoid, causes cell cycle arrest and apoptosis in a number of cancer cells including human breast carcinoma (HBC) by utilizing an undefined retinoic acid receptor/retinoid X receptor-independent mechanism. To delineate mediators of CD437 signaling, we utilized a random antisense-dependent functional knockout genetic approach. We identified a cDNA that encodes approximately 130-kDa HBC cell perinuclear protein (termed CARP-1). Treatments with CD437 or chemotherapeutic agent adriamycin, as well as serum deprivation of HBC cells, stimulate CARP-1 expression. Reduced levels of CARP-1 result in inhibition of apoptosis by CD437 or adriamycin, whereas increased expression of CARP-1 causes elevated levels of cyclin-dependent kinase inhibitor p21WAF1/CIP1 and apoptosis. CARP-1 interacts with 14-3-3 protein as well as causes reduced expression of cell cycle regulatory genes including c-Myc and cyclin B1. Loss of c-Myc sensitizes cells to apoptosis by CARP-1, whereas expression of c-Myc or 14-3-3 inhibits CARP-1-dependent apoptosis. Thus, apoptosis induction by CARP-1 involves sequestration of 14-3-3 and CARP-1-mediated altered expression of multiple cell cycle regulatory genes. Identification of CARP-1 as a key mediator of signaling by CD437 or adriamycin allows for delineation of pathways that, in turn, may prove beneficial for design and targeting of novel antitumor agents. PMID:12816952

  2. Inhibiting CREPT reduces the proliferation and migration of non-small cell lung cancer cells by down-regulating cell cycle related protein

    PubMed Central

    Liu, Tao; Li, Wei-Miao; Wang, Wu-Ping; Sun, Ying; Ni, Yun-Feng; Xing, Hao; Xia, Jing-Hua; Wang, Xue-Jiao; Zhang, Zhi-Pei; Li, Xiao-Fei

    2016-01-01

    It has been reported that CREPT acts as a highly expressed oncogene in a variety of tumors, affecting cyclin D1 signal pathways. However, the distribution and clinical significance of CREPT in NSCLC remains poorly understood. Our study focused on the role of CREPT on the regulation ofnon-small cell lung cancer (NSCLC). We found that CREPT mRNA and protein expression was significantly increased in NSCLC compared with adjacent lung tissues and was increased in various NSCLC cell lines compared with the normal human bronchial epithelial (HBE) cell line. siRNA-induced knockingdown of CREPT significantly inhibited the proliferation and migration of NSCLC cell lines by arresting cell cycle in S phase. Moreover, CREPT knocking down affected the expression of cell cycle proteins including c-mycand CDC25A. Finally, we found there were obvious correlations between CREPT with c-myc expression in histological type, differentiation, and pTNM stages of NSCLC (P<0.05, rs>0.3). Immunohistofluorescence studies demonstrated a co-localization phenomenon when CREPT and c-myc were expressed. Thus, we propose that CREPT may promote NSCLC cell growth and migration through the c-myc and CDC25A signaling molecules. PMID:27347318

  3. Cross-talk between ER and HER2 regulates c-MYC-mediated glutamine metabolism in aromatase inhibitor resistant breast cancer cells

    PubMed Central

    Chen, Zhike; Wang, Yuanzhong; Warden, Charles; Chen, Shiuan

    2015-01-01

    Resistance to endocrine therapies in hormone receptor (HR)-positive breast cancer is a significant clinical problem for a considerable number of patients. The oncogenic transcription factor c-MYC (hereafter referred to as MYC), which regulates glutamine metabolism in cancer cells, has been linked to endocrine resistance. We were interested in whether MYC-mediated glutamine metabolism is also associated with aromatase inhibitor (AI) resistant breast cancer. We studied the expression and regulation of MYC and the fects of inhibition of MYC expression in both AI sensitive and resistant breast cancer cells. Considering the role of MYC in glutamine metabolism, we evaluated the contribution of glutamine to the proliferation of AI sensitive and resistant cells, and performed RNA-sequencing to investigate mechanisms of MYC-mediated glutamine utilization in AI resistance. We found that glutamine metabolism was independent of estrogen but still required ER in AI resistant breast cancer cells. The expression of MYC oncogene was up-regulated through the cross-talk between estrogen receptor (ER) and human epidermal growth factor receptor 2 (HER2) in AI resistant breast cancer cells. Moreover, the glutamine transporter solute carrier family (SLC)1A5 was significantly up-regulated in AI resistant breast cancer cells. ER down-regulator fulvestrant inhibited MYC, SLC1A5, glutaminase (GLS) and glutamine consumption in AI resistant breast cancer cells. Inhibition of MYC, SLC1A5 and GLS decreased AI resistant breast cancer cell proliferation. Our study has uncovered that MYC expression is up-regulated by the cross-talk between ER and HER2 in AI resistant breast cancer cells. MYC-mediated glutamine metabolism is associated with AI resistance of breast cancer. PMID:25683269

  4. Modeling Protein Expression and Protein Signaling Pathways

    PubMed Central

    Telesca, Donatello; Müller, Peter; Kornblau, Steven M.; Suchard, Marc A.; Ji, Yuan

    2015-01-01

    High-throughput functional proteomic technologies provide a way to quantify the expression of proteins of interest. Statistical inference centers on identifying the activation state of proteins and their patterns of molecular interaction formalized as dependence structure. Inference on dependence structure is particularly important when proteins are selected because they are part of a common molecular pathway. In that case, inference on dependence structure reveals properties of the underlying pathway. We propose a probability model that represents molecular interactions at the level of hidden binary latent variables that can be interpreted as indicators for active versus inactive states of the proteins. The proposed approach exploits available expert knowledge about the target pathway to define an informative prior on the hidden conditional dependence structure. An important feature of this prior is that it provides an instrument to explicitly anchor the model space to a set of interactions of interest, favoring a local search approach to model determination. We apply our model to reverse-phase protein array data from a study on acute myeloid leukemia. Our inference identifies relevant subpathways in relation to the unfolding of the biological process under study. PMID:26246646

  5. Detection of HER-2/neu, c-myc amplification and p53 inactivation by FISH in Egyptian patients with breast cancer.

    PubMed

    Ismail, Manal F; Aly, Magdy Sayed; Khaled, Hussein M; Mohamed, Hanaa M

    2009-01-01

    Breast cancer is a leading cause of cancer-related deaths in women worldwide. The clinical course of this disease is highly variable and clinicians continuously search for prognostic parameters that can accurately predict prognosis, and indicate a suitable adjuvant therapy for each patient. Amplification of the two oncogenes HER-2/neu and c-myc and inactivation of the tumor suppressor gene p53 are frequently encountered in breast carcinomas. The purpose of this study was to use the fluorescence in situ hybridization (FISH) for the assessment of HER-2/neu and c-myc amplification and p53 inactivation and to relate these molecular markers with the commonly used clinical and pathological factors. The study was conducted on 34 tissue samples obtained from 33 females and 1 male with breast carcinomas and 17 samples obtained from 16 females and 1 male with benign breast lesions. Results revealed that the level of HER-2/neu, c-myc and p53 in the malignant group was significantly increased as compared to the benign group. On relating the level of the molecular markers to clinicopathological factors, p53 was significantly associated with increased patient's age. The sensitivity of the investigated markers significantly increased with larger tumor size. Concerning tumor grade, HER-2/neu and p53 showed a significant increase in low-grade tumors whereas c-myc showed a highly significant increase in high-grade tumors. With regard to disease staging, HER-2/neu and c-myc were the only markers that showed significant increase at late stages of disease. p53 and HER-2/neu were significantly associated with positive lymph nodal status. A significant correlation was obtained between the levels of the three biomarkers to each other. Conclusively, the combination of HER-2/neu, c-myc and p53 can stratify patients into different risk groups. PMID:19675743

  6. The B-WICH chromatin-remodelling complex regulates RNA polymerase III transcription by promoting Max-dependent c-Myc binding.

    PubMed

    Sadeghifar, Fatemeh; Böhm, Stefanie; Vintermist, Anna; Östlund Farrants, Ann-Kristin

    2015-05-19

    The chromatin-remodelling complex B-WICH, comprised of William syndrome transcription factor, the ATPase SNF2h and nuclear myosin, specifically activates RNA polymerase III transcription of the 5S rRNA and 7SL genes. However, the underlying mechanism is unknown. Using high-resolution MN walking we demonstrate here that B-WICH changes the chromatin structure in the vicinity of the 5S rRNA and 7SL RNA genes during RNA polymerase III transcription. The action of B-WICH is required for the binding of the RNA polymerase machinery and the regulatory factors c-Myc at the 5S rRNA and 7SL RNA genes. In addition to the c-Myc binding site at the 5S genes, we have revealed a novel c-Myc and Max binding site in the intergenic spacer of the 5S rDNA. This region also contains a region remodelled by B-WICH. We demonstrate that c-Myc binds to both sites in a Max-dependent way, and thereby activate transcription by acetylating histone H3. The novel binding patterns of c-Myc and Max link transcription of 5S rRNA to the Myc/Max/Mxd network. Since B-WICH acts prior to c-Myc and other factors, we propose a model in which the B-WICH complex is required to maintain an open chromatin structure at these RNA polymerase III genes. This is a prerequisite for the binding of additional regulatory factors. PMID:25883140

  7. Dynamics of the Ternary Complex Formed by c-Myc Interactor JPO2, Transcriptional Co-activator LEDGF/p75, and Chromatin*

    PubMed Central

    Hendrix, Jelle; van Heertum, Bart; Vanstreels, Els; Daelemans, Dirk; De Rijck, Jan

    2014-01-01

    Lens epithelium-derived growth factor (LEDGF/p75) is a transcriptional co-activator involved in targeting human immunodeficiency virus (HIV) integration and the development of MLL fusion-mediated acute leukemia. A previous study revealed that LEDGF/p75 dynamically scans the chromatin, and upon interaction with HIV-1 integrase, their complex is locked on chromatin. At present, it is not known whether LEDGF/p75-mediated chromatin locking is typical for interacting proteins. Here, we employed continuous photobleaching and fluorescence correlation and cross-correlation spectroscopy to investigate in vivo chromatin binding of JPO2, a LEDGF/p75- and c-Myc-interacting protein involved in transcriptional regulation. In the absence of LEDGF/p75, JPO2 performs chromatin scanning inherent to transcription factors. However, whereas the dynamics of JPO2 chromatin binding are decelerated upon interaction with LEDGF/p75, very strong locking of their complex onto chromatin is absent. Similar results were obtained with the domesticated transposase PogZ, another cellular interaction partner of LEDGF/p75. We furthermore show that diffusive JPO2 can oligomerize; that JPO2 and LEDGF/p75 interact directly and specifically in vivo through the specific interaction domain of JPO2 and the C-terminal domain of LEDGF/p75, comprising the integrase-binding domain; and that modulation of JPO2 dynamics requires a functional PWWP domain in LEDGF/p75. Our results suggest that the dynamics of the LEDGF/p75-chromatin interaction depend on the specific partner and that strong chromatin locking is not a property of all LEDGF/p75-binding proteins. PMID:24634210

  8. Cooperation between the polyomavirus Middle-T-antigen gene and the human c-myc oncogene in a rat thyroid epithelial differentiated cell line: Model of in vitro progression

    SciTech Connect

    Berlingieri, M.T.; Portella, G.; Grieco, M.; Santoro, M.; Fusco, A.

    1988-05-01

    Two rat thyroid epithelial differentiated cell lines, PC CI 3 and PC myc, were infected with the polyoma murine leukemia virus (PyMLV) carrying the Middle-T-antigen gene of polyomavirus. After infection, both cell lines acquired the typical markers of neoplastic transformation; however, the PC myc cells showed a greater malignant phenotype. Furthermore, the thyroid differentiated functions were completely suppressed in PC myc cells transformed by PyMLV, whereas they were, at least partially, retained in PC CI 3 cells transformed by PyMLV, and in particular, thyroglobulin synthesis and secretion were not affected at all. Since no differences in the expression of the middle-T-antigen gene were observed in the two PyMLV-transformed cell lines, the different properties shown by these two infected cell lines must be ascribed to the expression of the c-myc oncogene.

  9. Cooperation between the polyomavirus middle-T-antigen gene and the human c-myc oncogene in a rat thyroid epithelial differentiated cell line: model of in vitro progression.

    PubMed Central

    Berlingieri, M T; Portella, G; Grieco, M; Santoro, M; Fusco, A

    1988-01-01

    Two rat thyroid epithelial differentiated cell lines, PC Cl 3 and PC myc, were infected with the polyoma murine leukemia virus (PyMLV) carrying the Middle-T-antigen gene of polyomavirus. After infection, both cell lines acquired the typical markers of neoplastic transformation; however, the PC myc cells showed a greater malignant phenotype. Furthermore, the thyroid differentiated functions were completely suppressed in PC myc cells transformed by PyMLV, whereas they were, at least partially, retained in PC Cl 3 cells transformed by PyMLV, and in particular, thyroglobulin synthesis and secretion were not affected at all. Since no differences in the expression of the middle-T-antigen gene were observed in the two PyMLV-transformed cell lines, the different properties shown by these two infected cell lines must be ascribed to the expression of the c-myc oncogene. Images PMID:2838744

  10. Fuse-binding protein 1 is a target of the EZH2 inhibitor GSK343, in osteosarcoma cells.

    PubMed

    Xiong, Xifeng; Zhang, Jinli; Liang, Weiguo; Cao, Wenjuan; Qin, Shengnan; Dai, Libing; Ye, Dongping; Liu, Zhihe

    2016-08-01

    Osteosarcoma is the primary cancer of leaf tissue and is regarded as a differentiation disease caused by genetic and epigenetic changes which interrupt the osteoblast differentiation from mesenchymal stem cells. Because of its high malignancy degree and rapid development, the morbidity and mortality are high. The enhancer of zeste homolog 2 (EZH2) is a catalytic subunit of polycomb repressive complex 2 (PRC2) and has been demonstrated to be involved in a variety of biological processes, such as cell proliferation and program cell death. EZH2 impairs gene expression by catalyzing the tri-methylation of histone H3 lysine 27 (H3K27me3) which controls gene transcription epigenetically. It is reported that EZH2 expression is higher in osteosarcoma than in osteoblastoma and the highest expression of EZH2 is found in osteosarcoma with metastasis. In the past few years, several potent inhibitors of EZH2 have been discovered, and GSK343 is one of them. In this study, we found that GSK343 inhibited osteosarcoma cell viability, restrained cell cycle transition and promoted programmed cell death. GSK343 not only inhibited the expression of EZH2 and its target, c-Myc and H3K27me3, but it also inhibited fuse binding protein 1 (FBP1) expression, another c-Myc regulator. Furthermore, we found that FBP1 physically interacts with EZH2. Based on these results, we believe that GSK343 is a potential molecule for osteosarcoma clinical treatment. Other than the inhibition on EZH2-c-Myc signal pathway, we postulate that the inhibition on FBP1-c-Myc signal pathway is another potential underlying mechanism with which GSK343 inhibits osteosarcoma cell viability. PMID:27278257

  11. FOXO3a regulates reactive oxygen metabolism by inhibiting mitochondrial gene expression

    PubMed Central

    Ferber, E C; Peck, B; Delpuech, O; Bell, G P; East, P; Schulze, A

    2012-01-01

    Forkhead transcription factors of the O class (FOXOs) are important targets of the phosphatidylinositol 3-kinase/Akt pathway, and are key regulators of the cell cycle, apoptosis and response to oxidative stress. FOXOs have been shown to have tumour suppressor function and are important for stem cell maintenance. We have performed a detailed analysis of the transcriptional programme induced in response to Forkhead-box protein O3a (FOXO3a) activation. We observed that FOXO3a activation results in the repression of a large number of nuclear-encoded genes with mitochondrial function. Repression of these genes was mediated by FOXO3a-dependent inhibition of c-Myc. FOXO3a activation also caused a reduction in mitochondrial DNA copy number, expression of mitochondrial proteins, respiratory complexes and mitochondrial respiratory activity. FOXO3a has been previously implicated in the detoxification of reactive oxygen species (ROS) through induction of manganese-containing superoxide dismutase (SOD2). We observed that reduction in ROS levels following FOXO3a activation was independent of SOD2, but required c-Myc inhibition. Hypoxia increases ROS production from the mitochondria, which is required for stabilisation of the hypoxia-inducible factor-1α (HIF-1α). FOXO3a activation blocked the hypoxia-dependent increase in ROS and prevented HIF-1α stabilisation. Our data suggest that FOXO factors regulate mitochondrial activity through inhibition of c-Myc function and alter the hypoxia response. PMID:22139133

  12. FOXO3a regulates reactive oxygen metabolism by inhibiting mitochondrial gene expression.

    PubMed

    Ferber, E C; Peck, B; Delpuech, O; Bell, G P; East, P; Schulze, A

    2012-06-01

    Forkhead transcription factors of the O class (FOXOs) are important targets of the phosphatidylinositol 3-kinase/Akt pathway, and are key regulators of the cell cycle, apoptosis and response to oxidative stress. FOXOs have been shown to have tumour suppressor function and are important for stem cell maintenance. We have performed a detailed analysis of the transcriptional programme induced in response to Forkhead-box protein O3a (FOXO3a) activation. We observed that FOXO3a activation results in the repression of a large number of nuclear-encoded genes with mitochondrial function. Repression of these genes was mediated by FOXO3a-dependent inhibition of c-Myc. FOXO3a activation also caused a reduction in mitochondrial DNA copy number, expression of mitochondrial proteins, respiratory complexes and mitochondrial respiratory activity. FOXO3a has been previously implicated in the detoxification of reactive oxygen species (ROS) through induction of manganese-containing superoxide dismutase (SOD2). We observed that reduction in ROS levels following FOXO3a activation was independent of SOD2, but required c-Myc inhibition. Hypoxia increases ROS production from the mitochondria, which is required for stabilisation of the hypoxia-inducible factor-1α (HIF-1α). FOXO3a activation blocked the hypoxia-dependent increase in ROS and prevented HIF-1α stabilisation. Our data suggest that FOXO factors regulate mitochondrial activity through inhibition of c-Myc function and alter the hypoxia response. PMID:22139133

  13. AB106. Differential regulation of LncRNA-SARCC suppresses VHL-mutant RCC cell proliferation yet promotes VHL-normal RCC cell proliferation via modulating androgen receptor/HIF-2α/C-MYC axis under hypoxia

    PubMed Central

    Zhai, Wei

    2016-01-01

    Objective It is well established that hypoxia contributes to tumor progression in a HIF-2α-dependent manner in renal cell carcinoma (RCC), yet the role of LncRNAs involved in hypoxia-mediated RCC progression remains unclear. Here we demonstrate that LncRNA-SARCC is differentially regulated by hypoxia in a VHL-dependent manner both in tissue culture and in human RCC clinical samples. LncRNA-SARCC can suppress hypoxic cell cycle progression in the VHL-mutant RCC cells while derepress it in the VHL-restored RCC cells. Mechanism dissection reveals that LncRNA-SARCC can post-transcriptionally regulate androgen receptor (AR) by physically binding and destabilizing AR protein to suppress AR/HIF-2α/C-MYC signals. In return, HIF-2α can transcriptionally regulate the LncRNA-SARCC expression via binding to hypoxia responsive elements (HREs) on the promoter of LncRNA-SARCC. The negative feedback modulation between LncRNA-SARCC/AR complex and HIF-2α signaling may then lead to differentially modulate RCC progression in a VHL-dependent manner. Together, these results may provide us a new therapeutic approach via targeting this newly identified signal from LncRNA-SARCC to AR-mediated HIF-2α/C-MYC signals against RCC progression. Methods Human samples—surgical specimens from human ccRCC tissues were obtained from 16 patients in the Department of Urology, Shanghai Tenth People’s Hospital, Tongji Medical School (Shanghai, China), freshly frozen in liquid nitrogen and stored at −80 °C until use. OCT-embedded blocks were sectioned until cut planes were >70% tumor. Sections were collected for DNA, RNA, and protein extraction. Samples were cataloged, clinical information on cases was obtained through chart review, and patient identifiers were removed before analysis. Informed consent was obtained from patients and the study was approved by the Institutional Review Board of Tongji Medical College. Immunohistochemistry—immunohistochemical staining was performed as previously

  14. Triplex-forming oligonucleotides targeting c-MYC potentiate the anti-tumor activity of gemcitabine in a mouse model of human cancer.

    PubMed

    Boulware, Stephen B; Christensen, Laura A; Thames, Howard; Coghlan, Lezlee; Vasquez, Karen M; Finch, Rick A

    2014-09-01

    Antimetabolite chemotherapy remains an essential cancer treatment modality, but often produces only marginal benefit due to the lack of tumor specificity, the development of drug resistance, and the refractoriness of slowly proliferating cells in solid tumors. Here, we report a novel strategy to circumvent the proliferation-dependence of traditional antimetabolite-based therapies. Triplex-forming oligonucleotides (TFOs) were used to target site-specific DNA damage to the human c-MYC oncogene, thereby inducing replication-independent, unscheduled DNA repair synthesis (UDS) preferentially in the TFO-targeted region. The TFO-directed UDS facilitated incorporation of the antimetabolite, gemcitabine (GEM), into the damaged oncogene, thereby potentiating the anti-tumor activity of GEM. Mice bearing COLO 320DM human colon cancer xenografts (containing amplified c-MYC) were treated with a TFO targeted to c-MYC in combination with GEM. Tumor growth inhibition produced by the combination was significantly greater than with either TFO or GEM alone. Specific TFO binding to the genomic c-MYC gene was demonstrated, and TFO-induced DNA damage was confirmed by NBS1 accumulation, supporting a mechanism of enhanced efficacy of GEM via TFO-targeted DNA damage-induced UDS. Thus, coupling antimetabolite chemotherapeutics with a strategy that facilitates selective targeting of cells containing amplification of cancer-relevant genes can improve their activity against solid tumors, while possibly minimizing host toxicity. PMID:23681918

  15. Triplex-forming oligonucleotides targeting c-MYC potentiate the anti-tumor activity of gemcitabine in a mouse model of human cancer

    PubMed Central

    Boulware, Stephen B.; Christensen, Laura A.; Thames, Howard; Coghlan, Lezlee; Vasquez, Karen M.; Finch, Rick A.

    2014-01-01

    Antimetabolite chemotherapy remains an essential cancer treatment modality, but often produces only marginal benefit due to the lack of tumor specificity, the development of drug resistance, and the refractoriness of slowly-proliferating cells in solid tumors. Here, we report a novel strategy to circumvent the proliferation-dependence of traditional antimetabolite-based therapies. Triplex-forming oligonucleotides (TFOs) were used to target site-specific DNA damage to the human c-MYC oncogene, thereby inducing replication-independent, unscheduled DNA repair synthesis (UDS) preferentially in the TFO-targeted region. The TFO-directed UDS facilitated incorporation of the antimetabolite, gemcitabine (GEM), into the damaged oncogene, thereby potentiating the anti-tumor activity of GEM. Mice bearing COLO 320DM human colon cancer xenografts (containing amplified c-MYC) were treated with a TFO targeted to c-MYC in combination with GEM. Tumor growth inhibition produced by the combination was significantly greater than with either TFO or GEM alone. Specific TFO binding to the genomic c-MYC gene was demonstrated, and TFO-induced DNA damage was confirmed by NBS1 accumulation, supporting a mechanism of enhanced efficacy of GEM via TFO-targeted DNA damage-induced UDS. Thus, coupling antimetabolite chemotherapeutics with a strategy that facilitates selective targeting of cells containing amplification of cancer-relevant genes can improve their activity against solid tumors, while possibly minimizing host toxicity. PMID:23681918

  16. THE HEPARIN-BINDING DOMAIN AND V REGION OF FIBRONECTIN REGULATE APOPTOSIS BY SUPPRESSION OF P53 AND C-MYC IN HUMAN PRIMARY CELLS

    EPA Science Inventory

    In apoptosis the tumor suppressor p53 and oncogene c-myc, are usually upregulated. However, we report here an alternate pathway of regulation that is triggered by inflammatory-associated matrix fragments of fibronectin (FN) and leads to apoptosis. It is mediated by transcriptio...

  17. Generation of Genome Integration-free Induced Pluripotent Stem Cells from Fibroblasts of C57BL/6 Mice without c-Myc Transduction*

    PubMed Central

    Jincho, Yuko; Araki, Ryoko; Hoki, Yuko; Tamura, Chihiro; Nakamura, Miki; Ando, Shunsuke; Kasama, Yasuji; Abe, Masumi

    2010-01-01

    Although the induction of genome integration-free induced pluripotent stem cells (iPSCs) has been reported, c-Myc was still required for the efficient generation of these cells. Herein, we report mouse strain-dependent differences in the c-Myc dependence for iPSC generation and the successful generation of genome integration-free iPSCs without c-Myc transduction using C57BL/6 mouse embryonic fibroblasts. We performed 49 independent experiments and obtained a total of 24 iPSC clones, including 18 genome integration-free iPSC clones. These iPSCs were indistinguishable from embryonic stem cells and from iPSCs generated using other methods. Furthermore, the generation of three-factor iPSCs free of virus vectors revealed the contribution of c-Myc to the genomic integration of external genes. C57BL/6 is an inbred mouse strain with substantial advantages for use in genetic and molecular biological studies due to its use in the whole mouse genome sequencing project. Thus, the present series of C57BL/6 iPSCs generated by various procedures will serve as a valuable resource for future genetic studies of iPSC generation. PMID:20554535

  18. Direct short-term cytotoxic effects of BIBR 1532 on acute promyelocytic leukemia cells through induction of p21 coupled with downregulation of c-Myc and hTERT transcription.

    PubMed

    Bashash, D; Ghaffari, S H; Zaker, F; Hezave, K; Kazerani, M; Ghavamzadeh, A; Alimoghaddam, K; Mosavi, S A; Gharehbaghian, A; Vossough, P

    2012-01-01

    Acute promyelocytic leukemia (APL) is characterized by specific t(15;17), distinct morphologic picture, and clinical coagulopathy that contribute to the morbidity and mortality of the disease. This study aims to investigate the effects of antitelomerase compound BIBR1532 on APL cells (NB4). BIBR 1532 exerts a direct short-term growth suppressive effect in a concentration-dependent manner probably through downregulation of c-Myc and hTERT expression. Our results also suggest that induction of p21 and subsequent disturbance of Bax/Bcl-2 balanced ratio as well as decreased telomerase activity may be rational mechanisms for the potent/direct short-term cytotoxicity of high doses of BIBR1532 against NB4 cells. PMID:22236190

  19. Amplification of c-MYC and MLL Genes as a Marker of Clonal Cell Progression in Patients with Myeloid Malignancy and Trisomy of Chromosomes 8 or 11.

    PubMed

    Angelova, S; Jordanova, M; Spassov, B; Shivarov, V; Simeonova, M; Christov, I; Angelova, P; Alexandrova, K; Stoimenov, A; Nikolova, V; Dimova, I; Ganeva, P; Tzvetkov, N; Hadjiev, E; Toshkov, S

    2011-12-01

    Gene amplification (amp) is one of the basic mechanisms connected with overexpression of oncogenes. The c-MYC (located in 8q24) and MLL (located in 11q23) are the most often over represented genes that lead to a rapid proliferation of the affected cell clone in patients with myeloid neoplasms. Assessment of the level of amp c-MYC or amp MLL in the cases with trisomy 8 (+8) or trisomy 11 (+11) and myeloid malignances is necessary for a more precise estimation of the disease progression. A total of 26 patients with acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS) were included in the study: 18 with +8, six with +11 and two with complex karyotypes suspected of the partial trisomy. Routine cytogenetic analysis and fluorescent in situ hybridization (FISH) were applied to indicate the chromosome alterations and genes amp in the bone marrow cells. Amp c-MYC was observed in 12 from 18 (66.7%) patients with +8. All the patients with +11 demonstrated a different level of amp MLL. In most of the cases with MDS (9/10), the coincidence of the +8 or +11 with amp c-MYC or amp MLL, respectively, leads to transformation to AML and/or short overall survival. Our data suggest that amp c-MYC and amp MLL develop in conformity with +8 and +11, especially in cases with progressive deviations in the karyotype as an aggressive expansion of an aberrant cell clone and appearance of additional chromosome anomalies. PMID:24052708

  20. Analysis of premature termination in c-myc during transcription by RNA polymerase II in a HeLa nuclear extract.

    PubMed Central

    London, L; Keene, R G; Landick, R

    1991-01-01

    Transcriptional regulation of the human c-myc gene, an important aspect of cellular differentiation, occurs in part at the level of transcript elongation. In vivo, transcriptional arrest, due to either pausing or termination, occurs near the junction between the first exon and first intron and varies with the growth state of the cell. We have tested the transcription of c-myc templates in HeLa nuclear extracts. We did not observe significant arrest under standard conditions, but we found that a considerable fraction of transcription complexes stopped at the c-myc TII site (just past the first exon-intron junction) when the KCl concentration was raised to 400 mM during elongation. Transcriptional arrest at TII also was observed at KCl concentrations as low as 130 mM and when potassium acetate or potassium glutamate was substituted for KCl. Under these conditions, arrest occurred at the TII site when transcription was initiated at either the c-myc P2 promoter or the adenovirus 2 major late promoter. Further, the TII sequence itself, in forward but not reverse orientation, was sufficient to stop transcription in a HeLa nuclear extract. By separating the TII RNA from active transcription complexes by using gel filtration, we found that arrest at TII at 400 mM KCl resulted in transcript release and thus true transcriptional termination. The efficiency of termination at TII depended on the growth state of the cells from which the extracts were made, suggesting that some factor or factors control premature termination in c-myc. Images PMID:1715021

  1. An apolar extract of Critonia morifolia inhibits c-Myc, cyclin D1, Cdc25A, Cdc25B, Cdc25C and Akt and induces apoptosis.

    PubMed

    Unger, Christine; Popescu, Ruxandra; Giessrigl, Benedikt; Rarova, Lucie; Herbacek, Irene; Seelinger, Mareike; Diaz, Rene; Wallnöfer, Bruno; Fritzer-Szekeres, Monika; Szekeres, Thomas; Frisch, Richard; Doležal, Karel; Strnad, Miroslav; De Martin, Rainer; Grusch, Michael; Kopp, Brigitte; Krupitza, Georg

    2012-06-01

    Investigating the bioactivity of traditional medical remedies under the controlled conditions of a laboratory is an option to find additional applications, novel formulations or lead structures for the development of new drugs. The present work analysed the anti‑neoplastic activity of increasing polar extracts of the rainforest plant Critonia morifolia (Asteraceae) that has been successfully used as traditional remedy to treat various inflammatory conditions in the long-lasting medical tradition of the Central American Maya, which was here also confirmed in vitro. The apolar petroleum ether extract exhibited the most potent anti‑proliferative and pro‑apoptotic effects in HL‑60 cells and triggered down-regulation of Cdc25C and cyclin D1 within 30 min followed by the inhibition of c-Myc expression and the onset of caspase-3 activation within 2 h. Subsequent to these very rapid molecular responses Chk2 and H2AX became phosphorylated (γ‑H2AX) after 4 h. Analysis of the cell cycle distribution showed an accumulation of cells in the G2-M phase within 8 h and after 24 h in S-phase. This was temporally paralleled by the down-regulation of Cdc25A, Cdc25B, Wee1 and Akt. Therefore, the attenuation of cell cycle progression in the G2-M phase was consistent with the known role of Chk2 for G2-M arrest and with the role of Cdc25B in S-phase progression. These findings suggest the presence of two distinct active principles in the petroleum ether extract of C. moriflia. These facilitated the strong apoptotic response evidenced by the rapid activation of caspase-3 that was later enforced by the inhibition of the survival kinase Akt. Importantly, the efficient down-regulation of Akt, which is successfully tested in current clinical trials, is a unique property of C. morifolia. PMID:22446629

  2. Estrogen modulates the mRNA levels for cancellous bone protein of ovariectomized rats.

    PubMed

    Salih, M A; Liu, C C; Arjmandi, B H; Kalu, D N

    1993-12-01

    This study was undertaken to examine the effects of ovariectomy and 17 beta-estradiol (E2) on the gene expression of type 1 collagen, osteocalcin and the protooncogen, c-myc, in cancellous bone. Female Sprague-Dawley rats, aged 95 days, were divided into 4 groups. Group 1 was sham operated and Groups 2-4 were ovariectomized. Groups 3 and 4 received daily injections of 160 ng and 1600 ng E2/kg body weight, respectively. Groups 1 and 2 received the solvent vehicle. All animals were sacrificed after 14 days. The femurs were dissected out and cancellous bone scraped from the distal metaphysis. RNA was isolated from the cancellous bone, immobilized on filters or size-fractionated by agarose gel electrophoresis and adsorbed on filters which were then hybridized with specific cDNA probes. Ovariectomy resulted in a significant increase in the mRNAs of type 1 collagen, osteocalcin and c-myc. The increase was suppressed in animals that received 17 beta-estradiol injections. In addition, ovariectomy caused the expected decrease in cancellous bone in the proximal tibia and increased osteoclast and osteoblast numbers. The ovariectomy-induced changes were prevented by 17 beta-estradiol administration. These findings suggest that the lack of ovarian hormones shortly after ovariectomy up-regulates and estrogen administration down-regulates the expression of important cancellous bone matrix proteins as well as the protooncogen, c-myc. PMID:8148671

  3. A unique transactivation sequence motif is found in the carboxyl-terminal domain of the single-strand-binding protein FBP.

    PubMed Central

    Duncan, R; Collins, I; Tomonaga, T; Zhang, T; Levens, D

    1996-01-01

    The far-upstream element-binding protein (FBP) is one of several recently described factors which bind to a single strand of DNA in the 5' region of the c-myc gene. Although cotransfection of FBP increases expression from a far-upstream element-bearing c-myc promoter reporter, the mechanism of this stimulation is heretofore unknown. Can a single-strand-binding protein function as a classical transactivator, or are these proteins restricted to stabilizing or altering the conformation of DNA in an architectural role? Using chimeric GAL4-FBP fusion proteins we have shown that the carboxyl-terminal region (residues 448 to 644) is a potent transcriptional activation domain. This region contains three copies of a unique amino acid sequence motif containing tyrosine diads. Analysis of deletion mutants demonstrated that a single tyrosine motif alone (residues 609 to 644) was capable of activating transcription. The activation property of the C-terminal domain is repressed by the N-terminal 107 amino acids of FBP. These results show that FBP contains a transactivation domain which can function alone, suggesting that FBP contributes directly to c-myc transcription while bound to a single-strand site. Furthermore, activation is mediated by a new motif which can be negatively regulated by a repression domain of FBP. PMID:8628294

  4. High p27 protein levels in chronic lymphocytic leukemia are associated to low Myc and Skp2 expression, confer resistance to apoptosis and antagonize Myc effects on cell cycle.

    PubMed

    Caraballo, Juan M; Acosta, Juan C; Cortés, Miguel A; Albajar, Marta; Gómez-Casares, M Teresa; Batlle-López, Ana; Cuadrado, M Angeles; Onaindia, Arantza; Bretones, Gabriel; Llorca, Javier; Piris, Miguel A; Colomer, Dolors; León, Javier

    2014-07-15

    Myc (c-Myc) counteracts p27 effects, and low p27 usually correlates with high Myc expression in human cancer. However there is no information on the co-expression of both genes in chronic lymphocytic leukemia (CLL). We found a lack of correlation between RNA and protein levels of p27 and Myc in CLL cells, so we determined the protein levels by immunoblot in 107 cases of CLL. We observed a high p27 protein expression in CLL compared to normal B cells. Ectopic p27 expression in a CLL-derived cell line resulted in cell death resistance. Surprisingly, Myc expression was very low or undetectable in most CLL cases analyzed, with a clear correlation between high p27 and low Myc protein levels. This was associated with low Skp2 expression, which is consistent with the Skp2 role in p27 degradation and with SKP2 being a Myc target gene. High Myc expression did not correlate with leukemia progression, despite that cell cycle-related Myc target genes were upregulated. However, biochemical analysis showed that the high p27 levels inhibited cyclin-Cdk complexes even in Myc expressing CLL cells. Our data suggest that the combination of high p27 and low Myc is a marker of CLL cells which is mediated by Skp2. PMID:25051361

  5. High p27 protein levels in chronic lymphocytic leukemia are associated to low Myc and Skp2 expression, confer resistance to apoptosis and antagonize Myc effects on cell cycle

    PubMed Central

    Caraballo, Juan M.; Acosta, Juan C.; Cortés, Miguel A.; Albajar, Marta; Gómez-Casares, M. Teresa; Batlle-López, Ana; Cuadrado, M. Angeles; Onaindia, Arantza; Bretones, Gabriel; Llorca, Javier; Piris, Miguel A.; Colomer, Dolors; León, Javier

    2014-01-01

    Myc (c-Myc) counteracts p27 effects, and low p27 usually correlates with high Myc expression in human cancer. However there is no information on the co-expression of both genes in chronic lymphocytic leukemia (CLL). We found a lack of correlation between RNA and protein levels of p27 and Myc in CLL cells, so we determined the protein levels by immunoblot in 107 cases of CLL. We observed a high p27 protein expression in CLL compared to normal B cells. Ectopic p27 expression in a CLL-derived cell line resulted in cell death resistance. Surprisingly, Myc expression was very low or undetectable in most CLL cases analyzed, with a clear correlation between high p27 and low Myc protein levels. This was associated with low Skp2 expression, which is consistent with the Skp2 role in p27 degradation and with SKP2 being a Myc target gene. High Myc expression did not correlate with leukemia progression, despite that cell cycle-related Myc target genes were upregulated. However, biochemical analysis showed that the high p27 levels inhibited cyclin-Cdk complexes even in Myc expressing CLL cells. Our data suggest that the combination of high p27 and low Myc is a marker of CLL cells which is mediated by Skp2. PMID:25051361

  6. Data Mining for Expressivity of Recombinant Protein Expression

    NASA Astrophysics Data System (ADS)

    Kira, Satoshi; Isoai, Atsushi; Yamamura, Masayuki

    We analyzed the expressivity of recombinant proteins by using data mining methods. The expression technique of recombinant protein is a key step towards elucidating the functions of genes discovered through genomic sequence projects. We have studied the productive efficiency of recombinant proteins in fission yeast, Schizosaccharomyces pombe (S.pombe), by mining the expression results. We gathered 57 proteins whose expression levels were known roughly in the host. Correlation analysis, principal component analysis and decision tree analysis were applied to these expression data. Analysis featuring codon usage and amino acid composition clarified that the amino acid composition affected to the expression levels of a recombinant protein strongly than the effect of codon usage. Furthermore, analysis of amino acid composition showed that protein solubility and the metabolism cost of amino acids correlated with a protein expressivity. Codon usage was often interesting in the field of recombinant expressions. However, our analysis found the weak correlation codon features with expressivities. These results indicated that ready-made indices of codon bias were irrelevant ones for modeling the expressivities of recombinant proteins. Our data driven approach was an easy and powerful method to improve recombinant protein expression, and this approach should be concentrated attention with the huge amount of expression data accumulating through the post-genome era.

  7. Low expression of secreted frizzled-related protein 2 and nuclear accumulation of β-catenin in aggressive nonfunctioning pituitary adenoma

    PubMed Central

    WU, YOUTU; BAI, JIWEI; HONG, LINCHUAN; LIU, CHUNHUI; YU, SHENGYUAN; YU, GUOQIANG; ZHANG, YAZHUO

    2016-01-01

    The identification of a specific molecular marker for aggressiveness of nonfunctioning pituitary adenomas (NFPAs) is urgently required in order to guide the clinical diagnosis and treatment of NFPAs. In the present study, low expression of secreted frizzled-related protein 2 (sFRP2) in NFPAs was demonstrated by reverse transcription-quantitative polymerase chain reaction, western blot and immunohistochemical analyses. The results confirmed an abnormal accumulation of free β-catenin in the nuclei of NFPAs, which is the core step for the activation of the Wnt canonical signaling pathway. Furthermore, cyclin D1 and c-Myc, the downstream proteins of the Wnt canonical signaling pathway, were overexpressed in aggressive NFPAs. These findings demonstrated the activation of the Wnt canonical signaling pathway in aggressive NFPAs. In addition, sFRP2 expression was observed to be inversely correlated to the aggressiveness of NFPAs. Therefore, sFRP2 may act as a tumor suppressor through modulation of the cellular cytosolic pool of β-catenin in NFPAs. Furthermore, the expression of sFRP2 may serve as a biomarker for NFPAs aggressiveness and prognosis. PMID:27347125

  8. A Novel Secreted Protein, MYR1, Is Central to Toxoplasma ’s Manipulation of Host Cells

    DOE PAGESBeta

    Franco, Magdalena; Panas, Michael W.; Marino, Nicole D.; Lee, Mei-Chong Wendy; Buchholz, Kerry R.; Kelly, Felice D.; Bednarski, Jeffrey J.; Sleckman, Barry P.; Pourmand, Nader; Boothroyd, John C.

    2016-02-02

    The intracellular protozoanToxoplasma gondiidramatically reprograms the transcriptome of host cells it infects, including substantially up-regulating the host oncogene c-myc. By applying a flow cytometry-based selection to infected mouse cells expressing green fluorescent protein fused to c-Myc (c-Myc–GFP), we isolated mutant tachyzoites defective in this host c-Myc up-regulation. Whole-genome sequencing of three such mutants led to the identification ofMYR1(Mycregulation1;TGGT1_254470) as essential for c-Myc induction. MYR1 is a secreted protein that requires TgASP5 to be cleaved into two stable portions, both of which are ultimately found within the parasitophorous vacuole and at the parasitophorous vacuole membrane. Deletion ofMYR1revealed that in additionmore » to its requirement for c-Myc up-regulation, the MYR1 protein is needed for the ability ofToxoplasmatachyzoites to modulate several other important host pathways, including those mediated by the dense granule effectors GRA16 and GRA24. This result, combined with its location at the parasitophorous vacuole membrane, suggested that MYR1 might be a component of the machinery that translocatesToxoplasmaeffectors from the parasitophorous vacuole into the host cytosol. Support for this possibility was obtained by showing that transit of GRA24 to the host nucleus is indeed MYR1-dependent. As predicted by this pleiotropic phenotype, parasites deficient inMYR1were found to be severely attenuated in a mouse model of infection. We conclude, therefore, that MYR1 is a novel protein that plays a critical role in howToxoplasmadelivers effector proteins to the infected host cell and that this is crucial to virulence. IMPORTANCEToxoplasma gondiiis an important human pathogen and a model for the study of intracellular parasitism. Infection of the host cell withToxoplasmatachyzoites involves the introduction of protein effectors, including many that are initially secreted into the parasitophorous vacuole but must

  9. Predictable tuning of protein expression in bacteria.

    PubMed

    Bonde, Mads T; Pedersen, Margit; Klausen, Michael S; Jensen, Sheila I; Wulff, Tune; Harrison, Scott; Nielsen, Alex T; Herrgård, Markus J; Sommer, Morten O A

    2016-03-01

    We comprehensively assessed the contribution of the Shine-Dalgarno sequence to protein expression and used the data to develop EMOPEC (Empirical Model and Oligos for Protein Expression Changes; http://emopec.biosustain.dtu.dk). EMOPEC is a free tool that makes it possible to modulate the expression level of any Escherichia coli gene by changing only a few bases. Measured protein levels for 91% of our designed sequences were within twofold of the desired target level. PMID:26752768

  10. Mucin1 shifts Smad3 signaling from the tumor-suppressive pSmad3C/p21(WAF1) pathway to the oncogenic pSmad3L/c-Myc pathway by activating JNK in human hepatocellular carcinoma cells.

    PubMed

    Li, Qiongshu; Liu, Guomu; Yuan, Hongyan; Wang, Juan; Guo, Yingying; Chen, Tanxiu; Zhai, Ruiping; Shao, Dan; Ni, Weihua; Tai, Guixiang

    2015-02-28

    Mucin1 (MUC1) is a transmembrane glycoprotein that acts as an oncogene in human hepatic tumorigenesis. Hepatocellular carcinoma (HCC) cells often gain advantage by reducing the tumor-suppressive activity of transforming growth factor beta (TGF-β) together with stimulation of its oncogenic activity as in MUC1 expressing HCC cells; however, molecular mechanisms remain largely unknown. Type I TGF-β receptor (TβRI) and c-Jun NH2-terminal kinase (JNK) differentially phosphorylate Smad3 mediator to create 2 phosphorylated forms: COOH-terminally phosphorylated Smad3 (pSmad3C) and linker-phosphorylated Smad3 (pSmad3L). Here, we report that MUC1 overexpression in HCC cell lines suppresses TβRI-mediated pSmad3C signaling which involves growth inhibition by up-regulating p21(WAF1). Instead, MUC1 directly activates JNK to stimulate oncogenic pSmad3L signaling, which fosters cell proliferation by up-regulating c-Myc. Conversely, MUC1 gene silencing in MUC1 expressing HCC cells results in preserved tumor-suppressive function via pSmad3C, while eliminating pSmad3L-mediated oncogenic activity both in vitro and in vivo. In addition, high correlation between MUC1 and pSmad3L/c-Myc but not pSmad3C/p21(WAF1) expression was observed in HCC tissues from patients. Collectively, these results indicate that MUC1 shifts Smad3 signaling from a tumor-suppressive pSmad3C/p21(WAF1) to an oncogenic pSmad3L/c-Myc pathway by directly activating JNK in HCC cells, suggesting that MUC1 is an important target for HCC therapy. PMID:25714018

  11. Expression of multiple proteins in transgenic plants

    DOEpatents

    Vierstra, Richard D.; Walker, Joseph M.

    2002-01-01

    A method is disclosed for the production of multiple proteins in transgenic plants. A DNA construct for introduction into plants includes a provision to express a fusion protein of two proteins of interest joined by a linking domain including plant ubiquitin. When the fusion protein is produced in the cells of a transgenic plant transformed with the DNA construction, native enzymes present in plant cells cleave the fusion protein to release both proteins of interest into the cells of the transgenic plant. Since the proteins are produced from the same fusion protein, the initial quantities of the proteins in the cells of the plant are approximately equal.

  12. Persistence of immunoglobulin heavy chain/c-myc recombination-positive lymphocyte clones in the blood of human immunodeficiency virus-infected homosexual men.

    PubMed Central

    Müller, J R; Janz, S; Goedert, J J; Potter, M; Rabkin, C S

    1995-01-01

    We studied blood lymphocytes of human immunodeficiency virus (HIV)-seropositive and -negative homosexual men for the presence of T(8;14) translocations that recombine c-myc and immunoglobulin heavy-chain (IgH) mu/IgH alpha switch regions. Clones with T(8;14) translocations were detected in 10.5% (12/114) of the HIV-positive and in 2.0% of the 99 uninfected patients. The majority of recombinations were found at a single time point only. Four patients, however, harbored multiple (up to four) and persistent (up to 9 years) translocation-positive cell clones. No correlation between the presence of these aberrant lymphocytes and a later lymphoma could be established. The exon 1/intron 1 region of the recombined c-myc was investigated for the presence of point mutations and these were found in the nonpersistent clones. Additional alterations detected in these clones included duplications and a deletion in the c-myc gene. The pattern of base substitution indicates that they were introduced after the translocation event. Images Fig. 3 PMID:7604036

  13. SirT1 knockdown potentiates radiation-induced bystander effect through promoting c-Myc activity and thus facilitating ROS accumulation.

    PubMed

    Xie, Yuexia; Tu, Wenzhi; Zhang, Jianghong; He, Mingyuan; Ye, Shuang; Dong, Chen; Shao, Chunlin

    2015-02-01

    Radiation-induced bystander effect (RIBE) has important implications for secondary cancer risk assessment during cancer radiotherapy, but the bystander signaling processes, especially under hypoxic condition, are still largely unclear. The present study found that micronuclei (MN) formation could be induced in the non-irradiated HL-7702 hepatocyte cells after being treated with the conditioned medium from irradiated hepatoma HepG2 and SK-Hep-1 cells under either normoxia or hypoxia. This bystander response was dramatically diminished or enhanced when the SirT1 gene of irradiated hepatoma cells was overexpressed or knocked down, respectively, especially under hypoxia. Meanwhile, SirT1 knockdown promoted transcriptional activity for c-Myc and facilitated ROS accumulation. But both of the increased bystander responses and ROS generation due to SirT1-knockdown were almost completely suppressed by c-Myc interference. Moreover, ROS scavenger effectively abolished the RIBE triggered by irradiated hepatoma cells even with SirT1 depletion. These findings provide new insights that SirT1 has a profound role in regulating RIBE where a c-Myc-dependent release of ROS may be involved. PMID:25772107

  14. Cyclin E/Cdk2, P/CAF, and E1A regulate the transactivation of the c-myc promoter by FOXM1

    SciTech Connect

    Wierstra, Inken Alves, Juergen

    2008-03-28

    FOXM1c transactivates the c-myc promoter by binding directly to its TATA-boxes. The present study demonstrates that the transactivation of the c-myc promoter by FOXM1c is enhanced by the key proliferation signal cyclin E/Cdk2, but repressed by P/CAF and the adenoviral oncoprotein E1A. Furthermore, FOXM1c interacts with the coactivator and histone acetyltransferase P/CAF. This study shows that, on the c-myc-P1 TATA-box, FOXM1c does not function simply as normal transcription factor just binding to an unusual site. Moreover, the inhibitory N-terminus of FOXM1c does not inhibit its transrepression domain or its EDA. Others reported that a cyclin/Cdk-binding LXL-motif of the splice variant FoxM1b is required for its interaction with Cdk2, Cdk1, and p27, its phosphorylation by Cdk1 and its activation by Cdc25B. In contrast, we now demonstrate that this LXL-motif is not required for the activation of FOXM1c by cyclin D1/Cdk4, cyclin E/Cdk and cyclin A/Cdk2 or for the repression of FOXM1c by p27.

  15. Expression and purification of GST fusion proteins.

    PubMed

    Harper, S; Speicher, D W

    2001-05-01

    An increasingly common strategy for expressing proteins and large peptides in prokaryotic systems is to express the protein of interest connected to a "tag" that provides the basis for rapid high-affinity purification. This unit describes the expression and purification of fusion proteins containing the 26-kDa glutathione-S-transferase protein as well as methods for cleaving the affinity tag and repurifying the target protein. Advantages of this popular fusion protein system include high protein yields, high-affinity one-step protein purification of the fusion protein, existence of several alternative protease cleavage sites for removing the affinity tag when required, and ease of removal of the cleaved affinity tag. PMID:18429193

  16. Endoscopic appearance of AIDS-related gastrointestinal lymphoma with c-MYC rearrangements: Case report and literature review

    PubMed Central

    Tanaka, Shohei; Nagata, Naoyoshi; Mine, Sohtaro; Igari, Toru; Kobayashi, Taiichiro; Sugihara, Jun; Honda, Haruhito; Teruya, Katsuji; Kikuchi, Yoshimi; Oka, Shinichi; Uemura, Naomi

    2013-01-01

    Acquired immune deficiency syndrome (AIDS)-related lymphoma (ARL) remains the main cause of AIDS-related deaths in the highly active anti-retroviral therapy (HAART) era. Recently, rearrangement of MYC is associated with poor prognosis in patients with diffuse large B-cell lymphoma. Here, we report a rare case of gastrointestinal (GI)-ARL with MYC rearrangements and coinfected with Epstein-Barr virus (EBV) infection presenting with various endoscopic findings. A 38-year-old homosexual man who presented with anemia and was diagnosed with an human immunodeficiency virus infection for the first time. GI endoscopy revealed multiple dish-like lesions, ulcerations, bloody spots, nodular masses with active bleeding in the stomach, erythematous flat lesions in the duodenum, and multiple nodular masses in the colon and rectum. Magnified endoscopy with narrow band imaging showed a honeycomb-like pattern without irregular microvessels in the dish-like lesions of the stomach. Biopsy specimens from the stomach, duodenum, colon, and rectum revealed diffuse large B-cell lymphoma concomitant with EBV infection that was detected by high tissue EBV-polymerase chain reaction levels and Epstein-Barr virus small RNAs in situ hybridization. Fluorescence in situ hybridization analysis revealed a fusion between the immunoglobulin heavy chain (IgH) and c-MYC genes, but not between the IgH and BCL2 loci. After 1-mo of treatment with HAART and R-CHOP, endoscopic appearance improved remarkably, and the histological features of the biopsy specimens revealed no evidence of lymphoma. However, he died from multiple organ failure on the 139th day after diagnosis. The cause of his poor outcome may be related to MYC rearrangement. The GI tract involvement in ARL is rarely reported, and its endoscopic findings are various and may be different from those in non-AIDS GI lymphoma; thus, we also conducted a literature review of GI-ARL cases. PMID:23922484

  17. Transgenic rabbits with lymphocytic leukemia induced by the c-myc oncogene fused with the immunoglobulin heavy chain enhancer.

    PubMed Central

    Knight, K L; Spieker-Polet, H; Kazdin, D S; Oi, V T

    1988-01-01

    Transgenic rabbits with the rabbit c-myc oncogene fused with the rabbit immunoglobulin heavy chain enhancer region (E mu) DNA were developed by microinjecting pronuclei of single cell zygotes with the gene construct and implanting the microinjected eggs into pseudopregnant females. At age 17-20 days, 3 of 21 offspring born to seven females were found to have peripheral blood leukocyte counts of greater than 100,000 per mm3. Histology analyses showed extensive lymphocytic infiltration in the liver and kidney, indicating that these rabbits had a malignant lymphocytic leukemia. Genomic DNA analyses of thymus and peripheral blood lymphocytes revealed that the leukemic rabbits were transgenic and that both immunoglobulin heavy and kappa light chain genes were rearranged in the leukemic cells; thus, the leukemic cells are of B-cell lineage. One to four heavy and light chain gene rearrangements were observed, suggesting that the B-cell tumors were oligoclonal. Stable tissue culture cell lines from the bone marrow and peripheral blood of one of the transgenic rabbits have been developed. The development of B-cell leukemias in rabbits with the E mu-myc transgene contrasts with the development of B-cell lymphomas in mice carrying a similar transgene. The lymphomas in mice develop in adults and are monoclonal in origin. The leukemias in rabbits develop in juveniles, less than 3 weeks after birth, and appear oligoclonal in origin. The leukemias seem to develop in rabbit at a specific stage of development, and we suggest that a normal developmental signal may be involved in the oncogenesis. Images PMID:2834733

  18. Endoscopic appearance of AIDS-related gastrointestinal lymphoma with c-MYC rearrangements: case report and literature review.

    PubMed

    Tanaka, Shohei; Nagata, Naoyoshi; Mine, Sohtaro; Igari, Toru; Kobayashi, Taiichiro; Sugihara, Jun; Honda, Haruhito; Teruya, Katsuji; Kikuchi, Yoshimi; Oka, Shinichi; Uemura, Naomi

    2013-08-01

    Acquired immune deficiency syndrome (AIDS)-related lymphoma (ARL) remains the main cause of AIDS-related deaths in the highly active anti-retroviral therapy (HAART) era. Recently, rearrangement of MYC is associated with poor prognosis in patients with diffuse large B-cell lymphoma. Here, we report a rare case of gastrointestinal (GI)-ARL with MYC rearrangements and coinfected with Epstein-Barr virus (EBV) infection presenting with various endoscopic findings. A 38-year-old homosexual man who presented with anemia and was diagnosed with an human immunodeficiency virus infection for the first time. GI endoscopy revealed multiple dish-like lesions, ulcerations, bloody spots, nodular masses with active bleeding in the stomach, erythematous flat lesions in the duodenum, and multiple nodular masses in the colon and rectum. Magnified endoscopy with narrow band imaging showed a honeycomb-like pattern without irregular microvessels in the dish-like lesions of the stomach. Biopsy specimens from the stomach, duodenum, colon, and rectum revealed diffuse large B-cell lymphoma concomitant with EBV infection that was detected by high tissue EBV-polymerase chain reaction levels and Epstein-Barr virus small RNAs in situ hybridization. Fluorescence in situ hybridization analysis revealed a fusion between the immunoglobulin heavy chain (IgH) and c-MYC genes, but not between the IgH and BCL2 loci. After 1-mo of treatment with HAART and R-CHOP, endoscopic appearance improved remarkably, and the histological features of the biopsy specimens revealed no evidence of lymphoma. However, he died from multiple organ failure on the 139(th) day after diagnosis. The cause of his poor outcome may be related to MYC rearrangement. The GI tract involvement in ARL is rarely reported, and its endoscopic findings are various and may be different from those in non-AIDS GI lymphoma; thus, we also conducted a literature review of GI-ARL cases. PMID:23922484

  19. Establishment of c-myc-immortalized Kupffer cell line from a C57BL/6 mouse strain.

    PubMed

    Kitani, Hiroshi; Sakuma, Chisato; Takenouchi, Takato; Sato, Mitsuru; Yoshioka, Miyako; Yamanaka, Noriko

    2014-01-01

    We recently demonstrated in several mammalian species, a novel procedure to obtain liver-macrophages (Kupffer cells) in sufficient numbers and purity using a mixed primary culture of hepatocytes. In this study, we applied this method to the C57BL/6 mouse liver and established an immortalized Kupffer cell line from this mouse strain. The hepatocytes from the C57BL/6 adult mouse liver were isolated by a two-step collagenase perfusion method and cultured in T25 culture flasks. Similar to our previous studies, the mouse hepatocytes progressively changed their morphology into a fibroblastic appearance after a few days of culture. After 7-10 days of culture, Kupffer-like cells, which were contaminants in the hepatocyte fraction at the start of the culture, actively proliferated on the mixed fibroblastic cell sheet. At this stage, a retroviral vector containing the human c-myc oncogene and neomycin resistance gene was introduced into the mixed culture. Gentle shaking of the culture flask, followed by the transfer and brief incubation of the culture supernatant, resulted in a quick and selective adhesion of Kupffer cells to a plastic dish surface. After selection with G418 and cloning by limiting dilutions, a clonal cell line (KUP5) was established. KUP5 cells displayed typical macrophage morphology and were stably passaged at 4-5 days intervals for more than 5 months, with a population doubling time of 19 h. KUP5 cells are immunocytochemically positive for mouse macrophage markers, such as Mac-1, F4/80. KUP5 cells exhibited substantial phagocytosis of polystyrene microbeads and the release of inflammatory cytokines upon lipopolysaccharide stimulation. Taken together, KUP5 cells provide a useful means to study the function of Kupffer cells in vitro. PMID:25379377

  20. 1α,25-Dihydroxyvitamin D3 Inhibits C4-2 Prostate Cancer Cell Growth via a Retinoblastoma Protein (Rb)-Independent G1 Arrest

    PubMed Central

    Washington, Michele N.; Kim, Jung-Sun; Weigel, Nancy L.

    2010-01-01

    BACKGROUND The active metabolite of vitamin D, 1α,25-dihydroxyvitamin D3 (1,25D) reduces the growth of several prostate cancer cell lines, most commonly by inducing a cell cycle arrest in G1. This is mediated, in part, through down-regulation of c-Myc, a positive regulator of the transcription factor, E2F. There is evidence that prostate cancer cells lacking functional retinoblastoma protein (Rb), a negative regulator of E2F activity, are poorly responsive to 1,25D treatment. Since up to 60% of prostate cancers demonstrate a loss of heterozygosity for Rb, we sought to determine whether Rb is required for the growth inhibitory effects of 1,25D. METHODS Using siRNA, Rb was reduced in C4-2 prostate cancer cells, and the response of cells to 1,25D treatment or depletion of c-myc measured by [3H]-thymidine incorporation and flow cytometry. The effects of 1,25D treatment on E2F levels and activity, and E2F target gene expression were also measured. RESULTS 1,25D treatment and c-Myc depletion both cause a G1 arrest inhibiting C4-2 cell proliferation independently of Rb. 1,25D reduces c-Myc expression and causes a decrease in E2F and E2F target genes. Bcl-2, an E2F target and positive regulator of C4-2 cell growth, also is down-regulated by 1,25D independently of Rb. CONCLUSIONS Redundant growth inhibitory pathways compensate for the loss of Rb, and tumors lacking functional Rb may be responsive to 1,25D. PMID:20632309

  1. Coevolution of gene expression among interacting proteins

    SciTech Connect

    Fraser, Hunter B.; Hirsh, Aaron E.; Wall, Dennis P.; Eisen,Michael B.

    2004-03-01

    Physically interacting proteins or parts of proteins are expected to evolve in a coordinated manner that preserves proper interactions. Such coevolution at the amino acid-sequence level is well documented and has been used to predict interacting proteins, domains, and amino acids. Interacting proteins are also often precisely coexpressed with one another, presumably to maintain proper stoichiometry among interacting components. Here, we show that the expression levels of physically interacting proteins coevolve. We estimate average expression levels of genes from four closely related fungi of the genus Saccharomyces using the codon adaptation index and show that expression levels of interacting proteins exhibit coordinated changes in these different species. We find that this coevolution of expression is a more powerful predictor of physical interaction than is coevolution of amino acid sequence. These results demonstrate previously uncharacterized coevolution of gene expression, adding a different dimension to the study of the coevolution of interacting proteins and underscoring the importance of maintaining coexpression of interacting proteins over evolutionary time. Our results also suggest that expression coevolution can be used for computational prediction of protein protein interactions.

  2. Calmodulin-Dependent Protein Kinase mediates Hypergravity-Induced Changes in F-Actin Expression by Endothelial Cells

    NASA Technical Reports Server (NTRS)

    Love, Felisha D.; Melhado, Caroline; Bosah, Francis; Harris-Hooker, Sandra A.; Sanford, Gary L.

    1997-01-01

    A number of basic cellular functions, e.g., electrolyte concentration cell growth rate, glucose utilization, bone formation, response to growth stimulation and exocytosis are modified by microgravity or during spaceflight. Studies with intact animal during spaceflights have found lipid accumulations within the lumen of the vasculature and degeneration of the vascular wall. Capillary alterations with extensive endothelial invaginations were also seen. Hemodynamic studies have shown that there is a redistribution of blood from the lower extremities to the upper part of the body; this will alter vascular permeability, resulting in leakage into surrounding tissues. These studies indicate that changes in gravity will affect a number of physiological systems, including the vasculature. However, few studies have addressed the effect of microgravity on vascular cell function and metabolism. A major problem with ground based studies is that achieving a true microgravity hand, environment for prolonged period is not possible. On the other increasing gravity (i.e., hypergravity) is easily achieved. Several researchers have shown that hypergravity will increase the proliferation of several different cell limes (e.g., chick embryo fibroblasts) while decreasing cell motility and slowing liver regeneration following partial hepatectomy. These studies suggest that hypergravity will alter the behavior of most cells. Several investigators have shown that hypergravity affects the expression of the early response genes (c-fos and c-myc) and the activation of several protein kinases (PK's) in cells (10,11). In this study we investigated whether hypergravity alters the expression of f-actin by aortic endothelial cells, and the possible role of protein kinases (calmodulin(II)-dependent and PKA) as mediators of these effects.

  3. Role of the chromobox protein CBX7 in lymphomagenesis

    PubMed Central

    Scott, Clare L.; Gil, Jésus; Hernando, Eva; Teruya-Feldstein, Julie; Narita, Masako; Martínez, Dolores; Visakorpi, Tapio; Mu, David; Cordon-Cardo, Carlos; Peters, Gordon; Beach, David; Lowe, Scott W.

    2007-01-01

    Chromobox 7 (CBX7) is a chromobox family protein and a component of the Polycomb repressive complex 1 (PRC1) that extends the lifespan of cultured epithelial cells and can act independently of BMI-1 to repress the INK4a/ARF tumor suppressor locus. To determine whether CBX7 might be oncogenic, we examined its expression pattern in a range of normal human tissues and tumor samples. CBX7 was expressed at high levels in germinal center lymphocytes and germinal center-derived follicular lymphomas, where elevated expression correlated with high c-Myc expression and a more advanced tumor grade. By targeting Cbx7 expression to the lymphoid compartment in mice, we showed that Cbx7 can initiate T cell lymphomagenesis and cooperate with c-Myc to produce highly aggressive B cell lymphomas. Furthermore, Cbx7 repressed transcription from the Ink4a/Arf locus and acted epistatically to the Arf-p53 pathway during tumorigenesis. These data identify CBX7 as a chromobox protein causally linked to cancer development and may help explain the low frequency of INK4a/ARF mutations observed in human follicular lymphoma. PMID:17374722

  4. An AU-Rich Sequence Element (UUUN[A/U]U) Downstream of the Edited C in Apolipoprotein B mRNA Is a High-Affinity Binding Site for Apobec-1: Binding of Apobec-1 to This Motif in the 3′ Untranslated Region of c-myc Increases mRNA Stability

    PubMed Central

    Anant, Shrikant; Davidson, Nicholas O.

    2000-01-01

    Apobec-1, the catalytic subunit of the mammalian apolipoprotein B (apoB) mRNA-editing enzyme, is a cytidine deaminase with RNA binding activity for AU-rich sequences. This RNA binding activity is required for Apobec-1 to mediate C-to-U RNA editing. Filter binding assays, using immobilized Apobec-1, demonstrate saturable binding to a 105-nt apoB RNA with a Kd of ∼435 nM. A series of AU-rich templates was used to identify a high-affinity (∼50 nM) binding site of consensus sequence UUUN[A/U]U, with multiple copies of this sequence constituting the high-affinity binding site. In order to determine whether this consensus site could be functionally demonstrated from within an apoB RNA, circular-permutation analysis was performed, revealing one major (UUUGAU) and one minor (UU) site located 3 and 16 nucleotides, respectively, downstream of the edited base. Secondary-structure predictions reveal a stem-loop flanking the edited base with Apobec-1 binding to the consensus site(s) at an open loop. A similar consensus (AUUUA) is present in the 3′ untranslated regions of several mRNAs, including that of c-myc, that are known to undergo rapid degradation. In this context, it is presumed that the consensus motif acts as a destabilizing element. As an independent test of the ability of Apobec-1 to bind to this sequence, F442A cells were transfected with Apobec-1 and the half-life of c-myc mRNA was determined following actinomycin D treatment. These studies demonstrated an increase in the half-life of c-myc mRNA from 90 to 240 min in control versus Apobec-1-expressing cells. Apobec-1 expression mutants, in which RNA binding activity is eliminated, failed to alter c-myc mRNA turnover. Taken together, the data establish a consensus binding site for Apobec-1 embedded in proximity to the edited base in apoB RNA. Binding to this site in other target RNAs raises the possibility that Apobec-1 may be involved in other aspects of RNA metabolism, independent of its role as an apoB RNA

  5. Modulation of RIZ gene expression is associated to estradiol control of MCF-7 breast cancer cell proliferation.

    PubMed

    Gazzerro, Patrizia; Abbondanza, Ciro; D'Arcangelo, Andrea; Rossi, Mariangela; Medici, Nicola; Moncharmont, Bruno; Puca, Giovanni Alfredo

    2006-02-01

    The retinoblastoma protein-interacting zinc-finger (RIZ) gene, a member of the nuclear protein methyltransferase superfamily, is characterized by the presence of the N-terminal PR domain. The RIZ gene encodes for two proteins, RIZ1 and RIZ2. While RIZ1 contains the PR (PRDI-BF1 and RIZ homologous) domain, RIZ2 lacks it. RIZ gene expression is altered in a variety of human cancers and RIZ1 is now considered to be a candidate tumor suppressor. Estradiol treatment of MCF-7 cells produced a selective decrease of RIZ1 transcript and an increase of total RIZ mRNA. Experiments of chromatin immunoprecipitation indicated that RIZ2 protein expression was controlled by estrogen receptor and RIZ1 had a direct repressor function on c-myc gene expression. To investigate the role of RIZ gene products as regulators of the proliferation/differentiation transition, we analyzed the effects of forced suppression of RIZ1 induced in MCF-7 cells by siRNA of the PR domain-containing form. Silencing of RIZ1 expression stimulated cell proliferation, similar to the effect of estradiol on these cells, associated with a transient increase of c-myc expression. PMID:16356493

  6. Biological activities of v-myc and rearranged c-myc oncogenes in rat fibroblast cells in culture.

    PubMed

    Mougneau, E; Lemieux, L; Rassoulzadegan, M; Cuzin, F

    1984-09-01

    Two distinct forms of the myc oncogene were assayed for their ability to induce, in cultured rat fibroblast cells, the alterations of cellular growth controls observed upon transfer of the gene of polyoma virus encoding only the large T protein (plt). Both of these rearranged myc genes and the plt gene had been previously shown to cooperate with ras oncogenes for transformation of rat embryo fibroblasts (REF) and were thought to induce the same early step ("immortalization") of the tumoral transformation pathway. We now report that these two different oncogenes elicite the same response in the following biological assays: (i) reduction of the requirements in serum factors for growth in culture of cells of the established FR3T3 line; (ii) expression of transformed properties in low serum medium after transfer into FR3T3 cells expressing only the middle T protein of polyoma virus (MTT lines); (iii) conferring on REF cells the ability to grow as clonal colonies after seeding at low cell density; (iv) conferring on REF cells the ability to grow continuously in cell culture. These congruent phenotypes suggest that the activities of the large T and myc proteins result in the induction of the same molecular events. These results also provide simple biological assays and selective systems for oncogenes of the myc class. PMID:6091107

  7. Association of Nuclear PIM1 Expression with Lymph Node Metastasis and Poor Prognosis in Patients with Lung Adenocarcinoma and Squamous Cell Carcinoma

    PubMed Central

    Jiang, Richeng; Wang, Xinyue; Jin, Ziliang; Li, Kai

    2016-01-01

    Increasing evidence indicates that aberrant expression of PIM1, p-STAT3 and c-MYC is involved in the pathogenesis of various solid tumors, but its prognostic value is still unclear in non-small cell lung cancer (NSCLC). Here, we sought to evaluate the expression and prognostic role of these markers in patients with lung adenocarcinoma (AD) and squamous cell carcinoma (SCC). Real time RT-PCR and Western blotting was used to analyze the mRNA and protein expression of PIM1 in NSCLC cell lines, respectively. The expression of PIM1, p-STAT3, and c-MYC was immunohistochemically tested in archival tumor samples from 194 lung AD and SCC patients. High nuclear PIM1 expression was detected in 43.3% of ADs and SCCs, and was significantly correlated with lymph node (LN) metastasis (P = 0.028) and histology (P = 0.003). High nuclear PIM1 expression (P = 0.034), locally advanced stage (P < 0.001), AD (P = 0.007) and poor pathologic differentiation (P = 0.002) were correlated with worse disease-free survival (DFS). High nuclear PIM1 expression (P = 0.009), advanced clinical stage (P < 0.001) and poor pathologic differentiation (P = 0.004) were independent unfavorable prognostic factors for overall survival (OS). High p-STAT3 expression was not associated with OS but significantly correlated with LN metastasis, while c-MYC was not significantly correlated with any clinicopathological parameter or survival. Therefore, in AD and SCC patients, nuclear PIM1 expression level is an independent factor for DFS and OS and it might serve as a predictive biomarker for outcome. PMID:26918046

  8. Panagrellus redivivus ornithine decarboxylase: structure of the gene, expression in Escherichia coli and characterization of the recombinant protein.

    PubMed Central

    Niemann, G; von Besser, H; Walter, R D

    1996-01-01

    A southern blot analysis of the Panagrellus redivivus ornithine decarboxylase (ODC) gene suggests that it is a single-copy gene that resides on a genomic 3.2 kb EcoRI fragment. Phage clones possessing ODC gene sequences were isolated from a genomic EMBL-4 library and purified. The phage DNA inserts were analysed and a 3.2 kb EcoRI fragment containing the entire ODC gene was isolated. The nucleotide sequence analysis of this fragment reveals that the gene is interrupted by two introns of 47 and 49 bp. In the 5' non-translated region of the gene, putative AP1, VPE2 and c-Myc binding sites were identified. The ODC cDNA was expressed in a bacterial system as a His-fusion protein and the enzyme was purified by Ni(2+)-chelating affinity chromatography. The subunit molecular mass, as deduced from the cDNA and shown by SDS/PAGE, is 47.1 kDa. On the basis of gel filtration analyses it is shown that the active enzyme is a dimer. The specific enzyme activity was determined to be 4.2 mumol CO2/min/mg protein. The enzyme is dependent on pyridoxal 5-phosphate as a cofactor, and the presence of dithioerythritol or other thiol-reducing agents is essential for maximal activity. The Km value for L-ornithine was determined as 44 microM. The Ki values for putrescine, alpha-diffluoromethylornithine, alpha-hydrazino-ornithine and alpha-methylornithine were calculated as 51, 34, 0.34 and 42 microM respectively. PMID:8694755

  9. Suppression of protein kinase C and nuclear oncogene expression as possible action mechanisms of cancer chemoprevention by Curcumin.

    PubMed

    Lin, Jen-Kun

    2004-07-01

    Curcumin (diferuloylmethane) is a major naturally-occurring polyphenol of Curcuma species, which is commonly used as a yellow coloring and flavoring agent in foods. Curcumin has shown anti-carcinogenic activity in animal models. Curcumin possesses anti-inflammatory activity and is a potent inhibitor of reactive oxygen-generating enzymes such as lipoxygenase/cyclooxygenase, xanthine dehydrogenase/oxidase and inducible nitric oxide synthase; and an effective inducer of heme oxygenase-1. Curcumin is also a potent inhibitor of protein kinase C (PKC), EGF(Epidermal growth factor)-receptor tyrosine kinase and IkappaB kinase. Subsequently, curcumin inhibits the activation of NF(nucleor factor)kappaB and the expressions of oncogenes including c-jun, c-fos, c-myc, NIK, MAPKs, ERK, ELK, PI3K, Akt, CDKs and iNOS. It is proposed that curcumin may suppress tumor promotion through blocking signal transduction pathways in the target cells. The oxidant tumor promoter TPA activates PKC by reacting with zinc thiolates present within the regulatory domain, while the oxidized form of cancer chemopreventive agent such as curcumin can inactivate PKC by oxidizing the vicinal thiols present within the catalytic domain. Recent studies indicated that proteasome-mediated degradation of cell proteins play a pivotal role in the regulation of several basic cellular processes including differentiation, proliferation, cell cycling, and apoptosis. It has been demonstrated that curcumin-induced apoptosis is mediated through the impairment of ubiquitin-proteasome pathway. Curcumin was first biotransformed to dihydrocurcumin and tetrahydrocurcumin and that these compounds subsequently were converted to monoglucuronide conjugates. These results suggest that curcumin-glucuronide, dihydrocurcumin-glucuronide, tetrahydrocurcumin-glucuronide and tetrahydrocurcumin are the major metabolites of curcumin in mice, rats and humans. PMID:15356994

  10. Triphala Extract Suppresses Proliferation and Induces Apoptosis in Human Colon Cancer Stem Cells via Suppressing c-Myc/Cyclin D1 and Elevation of Bax/Bcl-2 Ratio

    PubMed Central

    Vadde, Ramakrishna; Radhakrishnan, Sridhar; Reddivari, Lavanya; Vanamala, Jairam K. P.

    2015-01-01

    Colon cancer is the second leading cause of cancer related deaths in the USA. Cancer stem cells (CSCs) have the ability to drive continued expansion of the population of malignant cells. Therefore, strategies that target CSCs could be effective against colon cancer and in reducing the risk of relapse and metastasis. In this study, we evaluated the antiproliferative and proapoptotic effects of triphala, a widely used formulation in Indian traditional medicine, on HCT116 colon cancer cells and human colon cancer stem cells (HCCSCs). The total phenolic content, antioxidant activity, and phytochemical composition (LC-MS-MS) of methanol extract of triphala (MET) were also measured. We observed that MET contains a variety of phenolics including naringin, quercetin, homoorientin, and isorhamnetin. MET suppressed proliferation independent of p53 status in HCT116 and in HCCSCs. MET also induced p53-independent apoptosis in HCCSCs as indicated by elevated levels of cleaved PARP. Western blotting data suggested that MET suppressed protein levels of c-Myc and cyclin D1, key proteins involved in proliferation, and induced apoptosis through elevation of Bax/Bcl-2 ratio. Furthermore, MET inhibited HCCSCs colony formation, a measure of CSCs self-renewal ability. Anticancer effects of triphala observed in our study warrant future studies to determine its efficacy in vivo. PMID:26167492

  11. Synthesis and evaluation of biphenyl derivatives as potential downregulators of VEGF protein secretion and telomerase-related gene expressions.

    PubMed

    Sánchez-Peris, María; Falomir, Eva; Murga, Juan; Carda, Miguel; Marco, J Alberto

    2016-07-15

    A group of 47 biphenyl functionalized compounds, prepared by means of Suzuki couplings, has been investigated for their cytotoxicity on two tumoral cell lines (HT-29 and MCF-7) and one non tumoral cell line (HEK-293). 29 selected compounds have been investigated for their ability to inhibit the production of the vascular endothelial growth factor (VEGF). Subsequently, the capacity of the compounds to downregulate the expression of the VEGF, h-TERT and c-Myc genes, the two latter involved in the control of the activation of telomerase, has also been determined. PMID:27259399

  12. Reduced expression of mir15a in the blood of patients with oral squamous cell carcinoma is associated with tumor staging

    PubMed Central

    RICIERI BRITO, JOÃO ARTUR; GOMES, CAROLINA CAVALIÉRI; SANTOS PIMENTA, FLÁVIO JULIANO GARCIA; BARBOSA, ALVIMAR AFONSO; PRADO, MARCO ANTÔNIO MÁXIMO; PRADO, VÂNIA FERREIRA; GOMEZ, MARCUS VINÍCIUS; GOMEZ, RICARDO SANTIAGO

    2010-01-01

    MicroRNAs (miRNAs) mir15a and let7a are important regulators of bcl-2, ras and c-myc proteins. Considering that these miRNAs are commonly altered in many human cancers and that these proteins are reported to be altered in oral squamous cell carcinoma (OSCC), we investigated them in a set of OSCC cases. The miRNAs as well as the proteins were evaluated in the tumor and blood of 20 patients by real-time quantitative PCR and immunohistochemistry, respectively. The expression of mir15a and bcl-2 proteins in the tumors was not associated with each other or with tumor staging. On the other hand, we found reduced expression of this miRNA in the blood of patients with an advanced stage of OSCC and with lymph node metastasis. The expression of let7a in the tumor and blood was not associated with tumor size, lymph node metastasis, tumor staging and immunoexpression of ras and c-myc proteins. In conclusion, the present study shows that reduced expression of mir15a is associated with OSCC staging. PMID:23136618

  13. CIP2A expression and prognostic role in patients with esophageal adenocarcinoma.

    PubMed

    Rantanen, Tuomo; Kauttu, Tuuli; Åkerla, Jonne; Honkanen, Teemu; Krogerus, Leena; Salo, Jarmo; Paavonen, Timo; Oksala, Niku

    2013-01-01

    CIP2A is overexpressed in many cancers, including esophageal squamous cell carcinoma. The regulation of c-MYC and CIP2A expression is characterized by a positive feedback mechanism facilitating the expression of both of them and accelerating cancer cell proliferation in gastric cancer. Increased CIP2A expression is a predictor of poor survival in some cancers. The incidence of positive CIP2A immunostaining and its association with c-MYC and its predictive value in esophageal adenocarcinoma are unknown. All esophageal adenocarcinoma patients from 1990 to 2007 with sufficient material for analysis of CIP2A and c-MYC in two university hospitals were included in the study. In addition, biopsies from Barrett's epithelium from the cancer patients and control tissue from normal esophageal mucosa adjacent to the tumor were included. CIP2A was moderately or strongly positive in 77.9 %, and c-MYC in 93.8 % of the cancer specimens. These frequencies were statistically different from the expression in normal esophageal epithelium. In addition, there was a positive correlation between CIP2A and c-MYC expression (p = 0.018). According to adjusted Cox regression survival analysis, CIP2A and c-MYC had no effect on survival. However, among patients with stage IVA-IVB cancer, there was a trend toward poor prognosis in CIP2A-positive patients. The expression of CIP2A and c-MYC was associated with each other, and their overexpression was found in most cases of esophageal adenocarcinoma. However, CIP2A and c-MYC had no effect on survival. PMID:23925667

  14. Partial Dedifferentiation of Murine Radial Glia-Type Neural Stem Cells by Brn2 and c-Myc Yields Early Neuroepithelial Progenitors.

    PubMed

    Bung, Raffaela; Wörsdörfer, Philipp; Thier, Marc Christian; Lemke, Kathrin; Gebhardt, Martina; Edenhofer, Frank

    2016-04-10

    Direct cell conversion developed into an important paradigm for generating cells with enhanced differentiation capability. We combined a transcription-factor-based cell fate conversion strategy with the use of pharmacological compounds to derive early neuroepithelial progenitor cells from developmentally more restricted radial glia-type neural stem cells. By combining the small molecules CHIR99021, Tranylcypromine, SB431542 and valproic acid with viral transduction of the transcription factor c-Myc and the POU domain transcription factor Brn2, we dedifferentiated radial glia-type neural stem cells into an early neuroepithelial progenitor cell state within 6days. Reverse transcription PCR analyses showed a rapid down-regulation of the radial glia markers Olig2 and Vimentin during conversion, whereas the neuroepithelial markers Dach1 and Sox1 were fastly up-regulated. Furthermore, a switch from N-Cadherin to E-Cadherin indicates a mesenchymal-to-epithelial transition. The differentiation of cells converted by Brn2/c-Myc yielded smooth muscle actin- and Peripherin-positive cells in addition to the neuronal marker TUJ1 and cells that are positive for the glial marker GFAP. This differentiation potential suggests that the applied reprogramming strategy induced an early neuroepithelial cell population, which might resemble cells of the neural border or even more primitive neuroepithelial cells. PMID:26555748

  15. Regulation of c-myc mRNA stability in vitro by a labile destabilizer with an essential nucleic acid component.

    PubMed Central

    Brewer, G; Ross, J

    1989-01-01

    The turnover rates of some mRNAs vary by an order of magnitude or more when cells change their growth pattern or differentiate. To identify regulatory factors that might be responsible for this variability, we investigated how cytosolic fractions affect mRNA decay in an in vitro system. A 130,000 X g supernatant (S130) from the cytosol of exponentially growing erythroleukemia cells contains a destabilizer that accelerates the decay of polysome-bound c-myc mRNA by eightfold or more compared with reactions lacking S130. The destabilizer is deficient in or absent from the S130 of cycloheximide-treated cells, indicating that it is labile or is repressed when translation is blocked. It is not a generic RNase, because it does not affect the turnover of delta-globin, gamma-globin, or histone mRNA and does not destabilize a major portion of polysomal polyadenylated mRNA. The destabilizer accelerates the turnover of the c-myc mRNA 3' region, as well as subsequent 3'-to-5' degradation of the mRNA body. It is inactivated in vitro by mild heating and by micrococcal nuclease, suggesting that it contains a nucleic acid component. c-myb mRNA is also destabilized in S130-supplemented in vitro reactions. These results imply that the stability of some mRNAs is regulated by cytosolic factors that are not associated with polysomes. Images PMID:2747642

  16. CAPER Is Vital for Energy and Redox Homeostasis by Integrating Glucose-Induced Mitochondrial Functions via ERR-α-Gabpa and Stress-Induced Adaptive Responses via NF-κB-cMYC

    PubMed Central

    Kang, Yun Kyoung; Putluri, Nagireddy; Maity, Suman; Tsimelzon, Anna; Ilkayeva, Olga; Mo, Qianxing; Lonard, David; Michailidis, George; Sreekumar, Arun; Newgard, Christopher B.; Wang, Meng; Tsai, Sophia Y.; Tsai, Ming-Jer; O'Malley, Bert W.

    2015-01-01

    Ever since we developed mitochondria to generate ATP, eukaryotes required intimate mito-nuclear communication. In addition, since reactive oxygen species are a cost of mitochondrial oxidative phosphorylation, this demands safeguards as protection from these harmful byproducts. Here we identified a critical transcriptional integrator which eukaryotes share to orchestrate both nutrient-induced mitochondrial energy metabolism and stress-induced nuclear responses, thereby maintaining carbon-nitrogen balance, and preserving life span and reproductive capacity. Inhibition of nutrient-induced expression of CAPER arrests nutrient-dependent cell proliferation and ATP generation and induces autophagy-mediated vacuolization. Nutrient signaling to CAPER induces mitochondrial transcription and glucose-dependent mitochondrial respiration via coactivation of nuclear receptor ERR-α-mediated Gabpa transcription. CAPER is also a coactivator for NF-κB that directly regulates c-Myc to coordinate nuclear transcriptome responses to mitochondrial stress. Finally, CAPER is responsible for anaplerotic carbon flux into TCA cycles from glycolysis, amino acids and fatty acids in order to maintain cellular energy metabolism to counter mitochondrial stress. Collectively, our studies reveal CAPER as an evolutionarily conserved ‘master’ regulatory mechanism by which eukaryotic cells control vital homeostasis for both ATP and antioxidants via CAPER-dependent coordinated control of nuclear and mitochondrial transcriptomic programs and their metabolisms. These CAPER dependent bioenergetic programs are highly conserved, as we demonstrated that they are essential to preserving life span and reproductive capacity in human cells—and even in C. elegans. PMID:25830341

  17. Transient Protein Expression by Agroinfiltration in Lettuce.

    PubMed

    Chen, Qiang; Dent, Matthew; Hurtado, Jonathan; Stahnke, Jake; McNulty, Alyssa; Leuzinger, Kahlin; Lai, Huafang

    2016-01-01

    Current systems of recombinant protein production include bacterial, insect, and mammalian cell culture. However, these platforms are expensive to build and operate at commercial scales and/or have limited abilities to produce complex proteins. In recent years, plant-based expression systems have become top candidates for the production of recombinant proteins as they are highly scalable, robust, safe, and can produce complex proteins due to having a eukaryotic endomembrane system. Newly developed "deconstructed" viral vectors delivered via Agrobacterium tumefaciens (agroinfiltration) have enabled robust plant-based production of proteins with a wide range of applications. The leafy Lactuca sativa (lettuce) plant with its strong foundation in agriculture is an excellent host for pharmaceutical protein production. Here, we describe a method for agroinfiltration of lettuce that can rapidly produce high levels of recombinant proteins in a matter of days and has the potential to be scaled up to an agricultural level. PMID:26614281

  18. The cancer-promoting gene fatty acid-binding protein 5 (FABP5) is epigenetically regulated during human prostate carcinogenesis.

    PubMed

    Kawaguchi, Koichiro; Kinameri, Ayumi; Suzuki, Shunsuke; Senga, Shogo; Ke, Youqiang; Fujii, Hiroshi

    2016-02-15

    FABPs (fatty-acid-binding proteins) are a family of low-molecular-mass intracellular lipid-binding proteins consisting of ten isoforms. FABPs are involved in binding and storing hydrophobic ligands such as long-chain fatty acids, as well as transporting these ligands to the appropriate compartments in the cell. FABP5 is overexpressed in multiple types of tumours. Furthermore, up-regulation of FABP5 is strongly associated with poor survival in triple-negative breast cancer. However, the mechanisms underlying the specific up-regulation of the FABP5 gene in these cancers remain poorly characterized. In the present study, we determined that FABP5 has a typical CpG island around its promoter region. The DNA methylation status of the CpG island in the FABP5 promoter of benign prostate cell