MiR-21 suppresses the anticancer activities of curcumin by targeting PTEN gene in human non-small cell lung cancer A549 cells.

PubMed

Zhang, W; Bai, W; Zhang, W

2014-08-01

Curcumin, a natural phytochemical, exhibits potent anticancer activities. Here, we sought to determine the molecular mechanisms underlying the cytotoxic effects of curcumin against human non-small cell lung cancer (NSCLC) cells. MTT assay and annexin-V/PI staining were used to analyze the effects of curcumin on the proliferation and apoptosis of A549 cells. The expression of microRNA-21 in curcumin-treated A549 cells was measured by quantitative real-time polymerase chain reaction assay. The protein level of phosphatase and tensin homolog (PTEN), a putative target of microRNA-21, was determined by Western blot analysis. Transfection of A549 cells with microRNA-21 mimic or PTEN small interfering RNA was performed to modulate the expression of microRNA-21 and PTEN under the treatment of curcumin. Curcumin at 20-40 μM inhibited cell proliferation and induced apoptosis in A549 cells. Curcumin treatment produced a dose-dependent and significant (P < 0.05) suppression of microRNA-21 expression, compared to untreated A549 cells. Moreover, the protein level of PTEN, a putative target of microRNA-21, was significantly elevated in curcumin-treated A549 cells, as determined by Western blot analysis. Transfection of A549 cells with microRNA-21 mimic or PTEN small interfering RNA significantly (P < 0.05) reversed the growth suppression and apoptosis induction by curcumin, compared to corresponding controls. Our data suggest a novel molecular mechanism in which inhibition of microRNA-21 and upregulation of PTEN mediate the anticancer activities of curcumin in NSCLC cells. Suppression of microRNA-21 may thus have therapeutic benefits against this malignancy.

An inducible knockout mouse to model the cell-autonomous role of PTEN in initiating endometrial, prostate and thyroid neoplasias.

PubMed

Mirantes, Cristina; Eritja, Núria; Dosil, Maria Alba; Santacana, Maria; Pallares, Judit; Gatius, Sónia; Bergadà, Laura; Maiques, Oscar; Matias-Guiu, Xavier; Dolcet, Xavier

2013-05-01

PTEN is one of the most frequently mutated tumor suppressor genes in human cancers. The role of PTEN in carcinogenesis has been validated by knockout mouse models. PTEN heterozygous mice develop neoplasms in multiple organs. Unfortunately, the embryonic lethality of biallelic excision of PTEN has inhibited the study of complete PTEN deletion in the development and progression of cancer. By crossing PTEN conditional knockout mice with transgenic mice expressing a tamoxifen-inducible Cre-ER(T) under the control of a chicken actin promoter, we have generated a tamoxifen-inducible mouse model that allows temporal control of PTEN deletion. Interestingly, administration of a single dose of tamoxifen resulted in PTEN deletion mainly in epithelial cells, but not in stromal, mesenchymal or hematopoietic cells. Using the mT/mG double-fluorescent Cre reporter mice, we demonstrate that epithelial-specific PTEN excision was caused by differential Cre activity among tissues and cells types. Tamoxifen-induced deletion of PTEN resulted in extremely rapid and consistent formation of endometrial in situ adenocarcinoma, prostate intraepithelial neoplasia and thyroid hyperplasia. We also analyzed the role of PTEN ablation in other epithelial cells, such as the tubular cells of the kidney, hepatocytes, colonic epithelial cells or bronchiolar epithelium, but those tissues did not exhibit neoplastic growth. Finally, to validate this model as a tool to assay the efficacy of anti-tumor drugs in PTEN deficiency, we administered the mTOR inhibitor everolimus to mice with induced PTEN deletion. Everolimus dramatically reduced the progression of endometrial proliferations and significantly reduced thyroid hyperplasia. This model could be a valuable tool to study the cell-autonomous mechanisms involved in PTEN-loss-induced carcinogenesis and provides a good platform to study the effect of anti-neoplastic drugs on PTEN-negative tumors.

An inducible knockout mouse to model the cell-autonomous role of PTEN in initiating endometrial, prostate and thyroid neoplasias

PubMed Central

Mirantes, Cristina; Eritja, Núria; Dosil, Maria Alba; Santacana, Maria; Pallares, Judit; Gatius, Sónia; Bergadà, Laura; Maiques, Oscar; Matias-Guiu, Xavier; Dolcet, Xavier

2013-01-01

SUMMARY PTEN is one of the most frequently mutated tumor suppressor genes in human cancers. The role of PTEN in carcinogenesis has been validated by knockout mouse models. PTEN heterozygous mice develop neoplasms in multiple organs. Unfortunately, the embryonic lethality of biallelic excision of PTEN has inhibited the study of complete PTEN deletion in the development and progression of cancer. By crossing PTEN conditional knockout mice with transgenic mice expressing a tamoxifen-inducible Cre-ERT under the control of a chicken actin promoter, we have generated a tamoxifen-inducible mouse model that allows temporal control of PTEN deletion. Interestingly, administration of a single dose of tamoxifen resulted in PTEN deletion mainly in epithelial cells, but not in stromal, mesenchymal or hematopoietic cells. Using the mT/mG double-fluorescent Cre reporter mice, we demonstrate that epithelial-specific PTEN excision was caused by differential Cre activity among tissues and cells types. Tamoxifen-induced deletion of PTEN resulted in extremely rapid and consistent formation of endometrial in situ adenocarcinoma, prostate intraepithelial neoplasia and thyroid hyperplasia. We also analyzed the role of PTEN ablation in other epithelial cells, such as the tubular cells of the kidney, hepatocytes, colonic epithelial cells or bronchiolar epithelium, but those tissues did not exhibit neoplastic growth. Finally, to validate this model as a tool to assay the efficacy of anti-tumor drugs in PTEN deficiency, we administered the mTOR inhibitor everolimus to mice with induced PTEN deletion. Everolimus dramatically reduced the progression of endometrial proliferations and significantly reduced thyroid hyperplasia. This model could be a valuable tool to study the cell-autonomous mechanisms involved in PTEN-loss-induced carcinogenesis and provides a good platform to study the effect of anti-neoplastic drugs on PTEN-negative tumors. PMID:23471917

Neonatal estrogenic exposure suppresses PTEN-related endometrial carcinogenesis in recombinant mice.

PubMed

Begum, Monjura; Tashiro, Hironori; Katabuchi, Hidetaka; Suzuki, Akira; Kurman, Robert J; Okamura, Hitoshi

2006-03-01

Human endometrial carcinomas, as well as complex atypical hyperplasias (CAH), are estrogen related and frequently have mutations in the PTEN gene. However, the mutual contribution of estrogen and PTEN mutations to endometrial carcinogenesis in vivo is unknown. To address this issue, we investigated whether neonatal estrogenic treatments augment the incidence of CAH and carcinomas in murine PTEN (mPTEN) heterozygous (+/-) mutant mice, an animal model for endometrial carcinoma. Low doses of diethylstilbestrol (1 ng/g/day), genistein (50 microg/g/day) in phytoestrogens, estriol (E(3)) (4 microg/g/day), and vehicle (ethanol and corn oil) were administered subcutaneously daily to neonatal pups from the 1st to 5th day after birth. At 52 weeks of age, the morphological changes in the endometrium, and uterine expression of Hoxa 10 and Hoxa 11, were evaluated. These Hoxa genes are abdominal B-type homeobox genes, which normally regulate differentiation of the Müllerian duct. The incidence of CAH and adenocarcinomas of the endometrium was significantly decreased by the neonatal estrogenic treatments in the mPTEN+/- mice. Coincidentally, all treatments significantly decreased the stromal cell density, and CAH and adenocarcinomas rarely developed in the epithelium adjacent to the affected endometrial stroma. Moreover, the uterine expression of Hoxa 10 in mice with neonatal genistein and E(3) treatments, and that of Hoxa 11 in mice with all treatments, was significantly lower when compared with vehicle alone. Taken together, neonatal estrogenic exposure induced stromal atrophy and/or hyalinization accompanied by repressed expression of Hoxa 10 and Hoxa 11, and exerted an inhibitory effect on PTEN-related tumorigenesis. These findings provide new insight into the interaction between endometrial epithelium and stroma in endometrial carcinogenesis in vivo.

Hyperactivity of newborn Pten knock-out neurons results from increased excitatory synaptic drive.

PubMed

Williams, Michael R; DeSpenza, Tyrone; Li, Meijie; Gulledge, Allan T; Luikart, Bryan W

2015-01-21

Developing neurons must regulate morphology, intrinsic excitability, and synaptogenesis to form neural circuits. When these processes go awry, disorders, including autism spectrum disorder (ASD) or epilepsy, may result. The phosphatase Pten is mutated in some patients having ASD and seizures, suggesting that its mutation disrupts neurological function in part through increasing neuronal activity. Supporting this idea, neuronal knock-out of Pten in mice can cause macrocephaly, behavioral changes similar to ASD, and seizures. However, the mechanisms through which excitability is enhanced following Pten depletion are unclear. Previous studies have separately shown that Pten-depleted neurons can drive seizures, receive elevated excitatory synaptic input, and have abnormal dendrites. We therefore tested the hypothesis that developing Pten-depleted neurons are hyperactive due to increased excitatory synaptogenesis using electrophysiology, calcium imaging, morphological analyses, and modeling. This was accomplished by coinjecting retroviruses to either "birthdate" or birthdate and knock-out Pten in granule neurons of the murine neonatal dentate gyrus. We found that Pten knock-out neurons, despite a rapid onset of hypertrophy, were more active in vivo. Pten knock-out neurons fired at more hyperpolarized membrane potentials, displayed greater peak spike rates, and were more sensitive to depolarizing synaptic input. The increased sensitivity of Pten knock-out neurons was due, in part, to a higher density of synapses located more proximal to the soma. We determined that increased synaptic drive was sufficient to drive hypertrophic Pten knock-out neurons beyond their altered action potential threshold. Thus, our work contributes a developmental mechanism for the increased activity of Pten-depleted neurons. Copyright © 2015 the authors 0270-6474/15/350943-17$15.00/0.

PTEN inhibition enhances angiogenesis in an in vitro model of ischemic injury by promoting Akt phosphorylation and subsequent hypoxia inducible factor-1α upregulation.

PubMed

Xue, Lixia; Huang, Jiankang; Zhang, Ting; Wang, Xiuzhe; Fu, Jianliang; Geng, Zhi; Zhao, Yuwu; Chen, Hao

2018-06-24

Angiogenesis is an important pathophysiological response to cerebral ischemia. PTEN is a lipid phosphatase whose loss activates PI3K/Akt signaling, which is related to HIF-1α upregulation and enhanced angiogenesis in human cancer cells. However, the specific roles of PTEN in endothelial cell functions and angiogenesis after cerebral ischemia remain unknown. Therefore, we sought to examine the potential effects of PTEN inhibition on post-ischemic angiogenesis in human blood vessel cells and to determine the underlying mechanism. In this present study, human umbilical vein endothelial cells (HUVECs) were exposed to oxygen-glucose deprivation (OGD), cell proliferation, migration and apoptosis, in vitro tube formation and expression of PTEN/Akt pathway and angiogenic factors were examined in HUVECs after treatment with PTEN inhibitor bisperoxovanadium (bpV) at different doses. The results showed that bpV significantly increased the cell proliferation and reduced cell apoptosis indicating that the drug exerts a cytoprotective effect on HUVECs with OGD exposure. bpV also enhanced cell migration and tube formation in HUVECs following OGD, and upregulated HIF-1α and VEGF expressions, but attenuated endostatin expression. Additionally, western blotting analysis demonstrated that Akt phosphorylation in HUVECs was significantly increased after bpV treatment. These findings suggest that PTEN inhibition promotes post-ischemic angiogenesis in HUVECs after exposure to OGD and this enhancing effect might be achieved through activation of the Akt signal cascade.

A PTEN inhibitor displays preclinical activity against hepatocarcinoma cells

PubMed Central

Augello, Giuseppa; Puleio, Roberto; Emma, Maria Rita; Cusimano, Antonella; Loria, Guido R.; McCubrey, James A.; Montalto, Giuseppe; Cervello, Melchiorre

2016-01-01

ABSTRACT Phosphatase and tensin homolog (PTEN) gene is considered a tumor suppressor gene. However, PTEN mutations rarely occur in hepatocellular carcinoma (HCC), whereas heterozygosity of PTEN, resulting in reduced PTEN expression, has been observed in 32–44% of HCC patients. In the present study, we investigated the effects of the small molecule PTEN inhibitor VO-OHpic in HCC cells. VO-OHpic inhibited cell viability, cell proliferation and colony formation, and induced senescence-associated β-galactosidase activity in Hep3B (low PTEN expression) and to a lesser extent in PLC/PRF/5 (high PTEN expression) cells, but not in PTEN-negative SNU475 cells. VO-OHpic synergistically inhibited cell viability when combined with PI3K/mTOR and RAF/MEK/ERK pathway inhibitors, but only in Hep3B cells, and significantly inhibited tumor growth in nude mice bearing xenografts of Hep3B cells. Therefore, we demonstrated for the first time that VO-OHpic inhibited cell growth and induced senescence in HCC cells with low PTEN expression, and that the combination of VO-OHpic with PI3K/mTOR and RAF/MEK/ERK inhibitors resulted in a more effective tumor cell kill. Our findings, hence, provide proof-of-principle evidence that pharmacological inhibition of PTEN may represent a promising approach for HCC therapy in a subclass of patients with a low PTEN expression. PMID:26794644

PTEN positively regulates UVB-induced DNA damage repair

PubMed Central

Ming, Mei; Feng, Li; Shea, Christopher R.; Soltani, Keyoumars; Zhao, Baozhong; Han, Weinong; Smart, Robert C.; Trempus, Carol S.; He, Yu-Ying

2011-01-01

Non-melanoma skin cancer is the most common cancer in the U.S., where DNA-damaging UVB radiation from the sun remains the major environmental risk factor. However, the critical genetic targets of UVB radiation are undefined. Here we show that attenuating PTEN in epidermal keratinocytes is a predisposing factor for UVB-induced skin carcinogenesis in mice. In skin papilloma and squamous cell carcinoma (SCC), levels of PTEN were reduced compared to skin lacking these lesions. Likewise, there was a reduction in PTEN levels in human premalignant actinic keratosis and malignant SCC, supporting a key role for PTEN in human skin cancer formation and progression. PTEN downregulation impaired the capacity of global genomic nucleotide excision repair (GG-NER), a critical mechanism for removing UVB-induced mutagenic DNA lesions. In contrast to the response to ionizing radiation, PTEN downregulation prolonged UVB-induced growth arrest and increased the activation of the Chk1 DNA damage pathway in an AKT-independent manner, likely due to reduced DNA repair. PTEN loss also suppressed expression of the key GG-NER protein xeroderma pigmentosum C (XPC) through the AKT/p38 signaling axis. Reconstitution of XPC levels in PTEN-inhibited cells restored GG-NER capacity. Taken together, our findings define PTEN as an essential genomic gatekeeper in the skin, through its ability to positively regulate XPC-dependent GG-NER following DNA damage. PMID:21771908

Differential role of PTEN in transforming growth factor β (TGF-β) effects on proliferation and migration in prostate cancer cells.

PubMed

Kimbrough-Allah, Mawiyah N; Millena, Ana C; Khan, Shafiq A

2018-04-01

Transforming growth factor-β (TGF-β) acts as a tumor suppressor in normal epithelial cells but as a tumor promoter in advanced prostate cancer cells. PI3-kinase pathway mediates TGF-β effects on prostate cancer cell migration and invasion. PTEN inhibits PI3-kinase pathway and is frequently mutated in prostate cancers. We investigated possible role(s) of PTEN in TGF-β effects on proliferation and migration in prostate cancer cells. Expression of PTEN mRNA and proteins were determined using RT-PCR and Western blotting in RWPE1 and DU145 cells. We also studied the role of PTEN in TGF-β effects on cell proliferation and migration in DU145 cells after transient silencing of endogenous PTEN. Conversely, we determined the role of PTEN in cell proliferation and migration after over-expression of PTEN in PC3 cells which lack endogenous PTEN. TGF-β1 and TGF-β3 had no effect on PTEN mRNA levels but both isoforms increased PTEN protein levels in DU145 and RWPE1 cells indicating that PTEN may mediate TGF-β effects on cell proliferation. Knockdown of PTEN in DU145 cells resulted in significant increase in cell proliferation which was not affected by TGF-β isoforms. PTEN overexpression in PC3 cells inhibited cell proliferation. Knockdown of endogenous PTEN enhanced cell migration in DU145 cells, whereas PTEN overexpression reduced migration in PC3 cells and reduced phosphorylation of AKT in response to TGF-β. We conclude that PTEN plays a role in inhibitory effects of TGF-β on cell proliferation whereas its absence may enhance TGF-β effects on activation of PI3-kinase pathway and cell migration. © 2018 Wiley Periodicals, Inc.

AKT activation promotes PTEN hamartoma tumor syndrome–associated cataract development

PubMed Central

Sellitto, Caterina; Li, Leping; Gao, Junyuan; Robinson, Michael L.; Lin, Richard Z.; Mathias, Richard T.; White, Thomas W.

2013-01-01

Mutations in the human phosphatase and tensin homolog (PTEN) gene cause PTEN hamartoma tumor syndrome (PHTS), which includes cataract development among its diverse clinical pathologies. Currently, it is not known whether cataract formation in PHTS patients is secondary to other systemic problems, or the result of the loss of a critical function of PTEN within the lens. We generated a mouse line with a lens-specific deletion of Pten (PTEN KO) and identified a regulatory function for PTEN in lens ion transport. Specific loss of PTEN in the lens resulted in cataract. PTEN KO lenses exhibited a progressive age-related increase in intracellular hydrostatic pressure, along with, increased intracellular sodium concentrations, and reduced Na+/K+-ATPase activity. Collectively, these defects lead to lens swelling, opacities and ultimately organ rupture. Activation of AKT was highly elevated in PTEN KO lenses compared to WT mice. Additionally, pharmacological inhibition of AKT restored normal Na+/K+-ATPase activity in primary cultured lens cells and reduced lens pressure in intact lenses from PTEN KO animals. These findings identify a direct role for PTEN in the regulation of lens ion transport through an AKT-dependent modulation of Na+/K+-ATPase activity, and provide a new animal model to investigate cataract development in PHTS patients. PMID:24270425

Cell Cycle Control by PTEN.

PubMed

Brandmaier, Andrew; Hou, Sheng-Qi; Shen, Wen H

2017-07-21

Continuous and error-free chromosome inheritance through the cell cycle is essential for genomic stability and tumor suppression. However, accumulation of aberrant genetic materials often causes the cell cycle to go awry, leading to malignant transformation. In response to genotoxic stress, cells employ diverse adaptive mechanisms to halt or exit the cell cycle temporarily or permanently. The intrinsic machinery of cycling, resting, and exiting shapes the cellular response to extrinsic stimuli, whereas prevalent disruption of the cell cycle machinery in tumor cells often confers resistance to anticancer therapy. Phosphatase and tensin homolog (PTEN) is a tumor suppressor and a guardian of the genome that is frequently mutated or deleted in human cancer. Moreover, it is increasingly evident that PTEN deficiency disrupts the fundamental processes of genetic transmission. Cells lacking PTEN exhibit cell cycle deregulation and cell fate reprogramming. Here, we review the role of PTEN in regulating the key processes in and out of cell cycle to optimize genomic integrity. Copyright © 2017 Elsevier Ltd. All rights reserved.

KRAS and BRAF Mutations and PTEN Expression Do Not Predict Efficacy of Cetuximab-Based Chemoradiotherapy in Locally Advanced Rectal Cancer

DOE Office of Scientific and Technical Information (OSTI.GOV)

Erben, Philipp, E-mail: philipp.erben@medma.uni-heidelberg.de; Stroebel, Philipp; Horisberger, Karoline

2011-11-15

Purpose: Mutations in KRAS and BRAF genes as well as the loss of expression of phosphatase and tensin homolog (PTEN) (deleted on chromosome 10) are associated with impaired activity of antibodies directed against epidermal growth factor receptor in patients with metastatic colorectal cancer. The predictive and prognostic value of the KRAS and BRAF point mutations as well as PTEN expression in patients with locally advanced rectal cancer (LARC) treated with cetuximab-based neoadjuvant chemoradiotherapy is unknown. Methods and Materials: We have conducted phase I and II trials of the combination of weekly administration of cetuximab and irinotecan and daily doses ofmore » capecitabine in conjunction with radiotherapy (45 Gy plus 5.4 Gy) in patients with LARC (stage uT3/4 or uN+). The status of KRAS and BRAF mutations was determined with direct sequencing, and PTEN expression status was determined with immunohistochemistry testing of diagnostic tumor biopsies. Tumor regression was evaluated by using standardized regression grading, and disease-free survival (DFS) was calculated according to the Kaplan-Meier method. Results: A total of 57 patients were available for analyses. A total of 31.6% of patients carried mutations in the KRAS genes. No BRAF mutations were found, while the loss of PTEN expression was observed in 9.6% of patients. Six patients achieved complete remission, and the 3-year DFS rate was 73%. No correlation was seen between tumor regression or DFS rate and a single marker or a combination of all markers. Conclusions: In the present series, no BRAF mutation was detected. The presence of KRAS mutations and loss of PTEN expression were not associated with impaired response to cetuximab-based chemoradiotherapy and 3-year DFS.« less

Apc inactivation, but not obesity, synergizes with Pten deficiency to drive intestinal stem cell-derived tumorigenesis.

PubMed

Tabrizian, Tahmineh; Wang, Donghai; Guan, Fangxia; Hu, Zunju; Beck, Amanda P; Delahaye, Fabien; Huffman, Derek M

2017-06-01

Obesity is a major risk factor for colorectal cancer and can accelerate Lgr5+ intestinal stem cell (ISC)-derived tumorigenesis after the inactivation of Apc However, whether non-canonical pathways involving PI3K-Akt signaling in ISCs can lead to tumor formation, and if this can be further exacerbated by obesity is unknown. Despite the synergy between Pten and Apc inactivation in epithelial cells on intestinal tumor formation, their combined role in Lgr5+-ISCs, which are the most rapidly dividing ISC population in the intestine, is unknown. Lgr5+-GFP mice were provided low-fat diet (LFD) or high-fat diet (HFD) for 8 months, and the transcriptome was evaluated in Lgr5+-ISCs. For tumor studies, Lgr5+-GFP and Lgr5+-GFP- Pten flox/flox mice were tamoxifen treated to inactivate Pten in ISCs and provided LFD or HFD until 14-15 months of age. Finally, various combinations of Lgr5+-ISC-specific, Apc- and Pten -deleted mice were generated and evaluated for histopathology and survival. HFD did not overtly alter Akt signaling in ISCs, but did increase other metabolic pathways. Pten deficiency, but not HFD, increased BrdU-positive cells in the small intestine ( P  < 0.05). However, combining Pten and Apc deficiency synergistically increased proliferative markers, tumor pathology and mortality, in a dose-dependent fashion ( P  < 0.05). In summary, we show that HFD alone fails to drive Akt signaling in ISCs and that Pten deficiency is dispensable as a tumor suppressor in Lgr5+-ISCs. However, combining Pten and Apc deficiency in ISCs synergistically increases proliferation, tumor formation and mortality. Thus, aberrant Wnt/β-catenin, rather than PI3K-Akt signaling, is requisite for obesity to drive Lgr5+ ISC-derived tumorigenesis. © 2017 Society for Endocrinology.

The Smad4/PTEN Expression Pattern Predicts Clinical Outcomes in Colorectal Adenocarcinoma.

PubMed

Chung, Yumin; Wi, Young Chan; Kim, Yeseul; Bang, Seong Sik; Yang, Jung-Ho; Jang, Kiseok; Min, Kyueng-Whan; Paik, Seung Sam

2018-01-01

Smad4 and PTEN are prognostic indicators for various tumor types. Smad4 regulates tumor suppression, whereas PTEN inhibits cell proliferation. We analyzed and compared the performance of Smad4 and PTEN for predicting the prognosis of patients with colorectal adenocarcinoma. Combined expression patterns based on Smad4+/- and PTEN+/- status were evaluated by immunostaining using a tissue microarray of colorectal adenocarcinoma. The relationships between the protein expression and clinicopathological variables were analyzed. Smad4-/PTEN- status was most frequently observed in metastatic adenocarcinoma, followed by primary adenocarcinoma and tubular adenoma (p<.001). When Smad4-/PTEN- and Smad4+/PTEN+ groups were compared, Smad4-/PTEN- status was associated with high N stage (p=.018) and defective mismatch repair proteins (p=.006). Significant differences in diseasefree survival and overall survival were observed among the three groups (Smad4+/PTEN+, Smad4-/PTEN+ or Smad4+/PTEN-, and Smad4-/PTEN-) (all p<.05). Concurrent loss of Smad4 and PTEN may lead to more aggressive disease and poor prognosis in patients with colorectal adenocarcinoma compared to the loss of Smad4 or PTEN alone.

[Research on the expression of Survivin and PTEN in laryngeal squamous cell carcinoma transplanted on the back sides of nude mice treated by gold throat tablets].

PubMed

Guo, Qiangzhong; Li, Yunying

2012-12-01

To explore the positive expressing rates of oncogene Survivin and tumor-suppressor gene PTEN in transplanted laryngo-carcinoma of nude mice treated by Gold Throat Tablets (GTT) which can improve circulation and remove haemostasis in TCM theory. The 32 nude mice seeded with cultured laryngeal carcinoma cells subcutaneously at the back were randomly divided into high, middle, low (according to 6 : 3: 1 proportion of GTT dosing given by intragastric administration) dose groups and blank control groups. The changes on weight and size of tumors originated from these cells were observed for 28 days, and the density of tumors and expression of Survivin and PTEN were examined with tumor sections by immunohistochemical assay after separating tumors from back of nude mice. The weight and size of subcutaneous laryngo-carcinoma on backs of high dose group nude mice were both the smallest among all the experimental groups with the average density of tumors as 1.202 g/cm3. The positive expressing rates of Survivin and PTEN both revealed the following tendency that high dose group < middle dose group < low dose group < blank control group. Six times of regular doses of GTT can prevent overgrowth of laryngo-carcinoma transplanted on nude mice and decrease the excessive expression of oncogene Survivin in the tumor. PTEN, expressing lower than Survivin in all groups, shows a subordinative relationship with it, maybe due to a competition mechanism.

PNUTS functions as a proto-oncogene by sequestering PTEN

PubMed Central

Kavela, Sridhar; Shinde, Swapnil R; Ratheesh, Raman; Viswakalyan, Kotapalli; Bashyam, Murali D; Gowrishankar, Swarnalata; Vamsy, Mohana; Pattnaik, Sujit; Rao, Subramanyeshwar; Sastry, Regulagadda A; Srinivasulu, Mukta; Chen, Junjie; Maddika, Subbareddy

2012-01-01

PTEN is a well-defined tumor suppressor gene that antagonizes the PI3K/Akt pathway to regulate a multitude of cellular processes such as survival, growth, motility, invasiveness and angiogenesis. While the functions of PTEN have been studied extensively, the regulation of its activity during normal and disease conditions still remains incompletely understood. In this study, we identified the protein phosphatase-1 nuclear targeting subunit PNUTS (PPP1R10) as a PTEN associated protein. PNUTS directly interacted with the lipid-binding domain (C2 domain) of PTEN and sequestered it in the nucleus. Depletion of PNUTS leads to increased apoptosis and reduced cellular proliferation in a PTEN-dependent manner. PNUTS expression was elevated in certain cancers compared to matched normal tissues. Collectively, our studies reveal PNUTS as a novel PTEN regulator and a likely oncogene. PMID:23117887

PTEN status in advanced colorectal cancer treated with cetuximab

PubMed Central

Negri, F V; Bozzetti, C; Lagrasta, C A; Crafa, P; Bonasoni, M P; Camisa, R; Pedrazzi, G; Ardizzoni, A

2009-01-01

Background: Loss of phosphatase and tensin homologue deleted in chromosome 10 (PTEN) function in advanced colorectal cancer (CRC) may represent one of the resistance mechanisms to cetuximab by interfering with the epidermal growth factor receptor signal transduction pathway. Methods: PTEN expression tested by indirect immunofluorescence was evaluated both on primary (n=43) and on metastatic (n=24) sites in CRC patients treated with cetuximab. Results: The loss of PTEN expression tested on metastatic sites was negatively associated with response (100% progressive disease (PD) in PTEN-negative cases vs 30% PD in PTEN-positive cases; P<0.05), PFS (0.8 vs 8.2 months; P<0.001) and OS (2.9 vs 14.2 months; P<0.001). Conclusion: A potential role of PTEN in the anti-tumour activity of cetuximab could be hypothesised. PMID:19953097

PTEN Overexpression Cooperates With Lithium to Reduce the Malignancy and to Increase Cell Death by Apoptosis via PI3K/Akt Suppression in Colorectal Cancer Cells.

PubMed

de Araujo, Wallace Martins; Robbs, Bruno Kaufmann; Bastos, Lilian G; de Souza, Waldemir F; Vidal, Flávia C B; Viola, João P B; Morgado-Diaz, Jose A

2016-02-01

Lithium is a well-established non-competitive inhibitor of glycogen synthase kinase-3β (GSK-3β), a kinase that is involved in several cellular processes related to cancer progression. GSK-3β is regulated upstream by PI3K/Akt, which is negatively modulated by PTEN. The role that lithium plays in cancer is controversial because lithium can activate or inhibit survival signaling pathways depending on the cell type. In this study, we analyzed the mechanisms by which lithium can modulate events related to colorectal cancer (CRC) progression and evaluated the role that survival signaling pathways such as PI3K/Akt and PTEN play in this context. We show that the administration of lithium decreased the proliferative potential of CRC cells in a GSK-3β-independent manner but induced the accumulation of cells in G2/M phase. Furthermore, high doses of lithium increased apoptosis, which was accompanied by decreased proteins levels of Akt and PTEN. Then, cells that were induced to overexpress PTEN were treated with lithium; we observed that low doses of lithium strongly increased apoptosis. Additionally, PTEN overexpression reduced proliferation, but this effect was minor compared with that in cells treated with lithium alone. Furthermore, we demonstrated that PTEN overexpression and lithium treatment separately reduced cell migration, colony formation, and invasion, and these effects were enhanced when lithium treatment and PTEN overexpression were combined. In conclusion, our findings indicate that PTEN overexpression and lithium treatment cooperate to reduce the malignancy of CRC cells and highlight lithium and PTEN as potential candidates for studies to identify new therapeutic approaches for CRC treatment. © 2015 Wiley Periodicals, Inc.

Understanding the tumor suppressor PTEN in chronic alcoholism and hepatocellular carcinoma.

PubMed

Shearn, Colin T; Petersen, Dennis R

2015-01-01

The tumor suppressor phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is a phosphatidylinositol (PtdIns) phosphatase that regulates Akt activation via PtdIns 3 kinase. Changes in PTEN expression and/or activity have been identified in a variety of chronic hepatocellular disorders including obesity, NAFLD, NASH, and alcoholism. In cancer biology, PTEN is frequently mutated or deleted in a wide variety of tumors. Mutations, decreased promoter activity, and decreased expression in PTEN are frequently identified in patients with hepatocellular carcinoma. While the majority of research on PTEN concerns obesity and NASH, PTEN clearly has a role in hepatic insulin sensitivity and in the development of steatosis during chronic alcoholism. Yet, in chronic alcoholics and HCC, very little is known concerning PTEN mutation/deletion or low PTEN expression. This review is focused on an overview of the current knowledge on molecular mechanisms of dysregulation of PTEN expression/activity in the liver and their relationship to development of ethanol-induced hepatocellular damage and cancer.

PTEN knockdown alters dendritic spine/protrusion morphology, not density

PubMed Central

Haws, Michael E.; Jaramillo, Thomas C.; Espinosa-Becerra, Felipe; Widman, Allie; Stuber, Garret D.; Sparta, Dennis R.; Tye, Kay M.; Russo, Scott J.; Parada, Luis F.; Kaplitt, Michael; Bonci, Antonello; Powell, Craig M.

2014-01-01

Mutations in phosphatase and tensin homolog deleted on chromosome ten (PTEN) are implicated in neuropsychiatric disorders including autism. Previous studies report that PTEN knockdown in neurons in vivo leads to increased spine density and synaptic activity. To better characterize synaptic changes in neurons lacking PTEN, we examined the effects of shRNA knockdown of PTEN in basolateral amygdala neurons on synaptic spine density and morphology using fluorescent dye confocal imaging. Contrary to previous studies in dentate gyrus, we find that knockdown of PTEN in basolateral amygdala leads to a significant decrease in total spine density in distal dendrites. Curiously, this decreased spine density is associated with increased miniature excitatory post-synaptic current frequency and amplitude, suggesting an increase in number and function of mature spines. These seemingly contradictory findings were reconciled by spine morphology analysis demonstrating increased mushroom spine density and size with correspondingly decreased thin protrusion density at more distal segments. The same analysis of PTEN conditional deletion in dentate gyrus demonstrated that loss of PTEN does not significantly alter total density of dendritic protrusions in the dentate gyrus, but does decrease thin protrusion density and increases density of more mature mushroom spines. These findings suggest that, contrary to previous reports, PTEN knockdown may not induce de novo spinogenesis, but instead may increase synaptic activity by inducing morphological and functional maturation of spines. Furthermore, behavioral analysis of basolateral amygdala PTEN knockdown suggests that these changes limited only to the basolateral amygdala complex may not be sufficient to induce increased anxiety-related behaviors. PMID:24264880

Osthole Induces Cell Cycle Arrest and Inhibits Migration and Invasion via PTEN/Akt Pathways in Osteosarcoma.

PubMed

Wang, Lu; Yang, Lei; Lu, Ying; Chen, Yingzhun; Liu, Tianhua; Peng, Yanli; Zhou, Yuhong; Cao, Yang; Bi, Zhenggang; Liu, Tianyi; Liu, Zhenhong; Shan, Hongli

2016-01-01

Osteosarcoma is the second highest cause of cancer-related death in children and adolescents. Majority of osteosarcoma patients (90%) show metastasis. Previous reports revealed that osthole showed antitumor activities via induction of apoptosis and inhibition of proliferation. However, the potential effects and detailed molecular mechanisms involved remained unclear. Cell viability was analyzed by MTT assay in osteosarcoma cell lines MG-63 and SAOS-2. Cell cycle was detected by flow cytometry. The effects of migration and invasion were evaluated by wound healing assay and transwell assays. Moreover, the level of proteins expression was determined by Western blot. The cell viability of MG63 and SAOS-2 were markedly inhibited by osthole in a dose- and time-dependent manner. Cell cycle was arrested and the ability of migration and invasion was obviously reduced when cells were exposed to osthole. Moreover, enzymes involved in PTEN/Akt pathway were regulated such as PTEN and p-Akt proteins. Furthermore, osthole inhibited the tumor growth in vivo. Our study unraveled, for the first time, the ability of osthole to suppress osteosarcoma and elucidated the regulation of PTEN/Akt pathway as a signaling mechanism for the anti-tumor action of osthole. These findings indicate that osthole may represent a novel therapeutic strategy in the treatment of osteosarcoma. © 2016 The Author(s) Published by S. Karger AG, Basel.

Biochemical screening and PTEN mutation analysis in individuals with autism spectrum disorders and macrocephaly

PubMed Central

Hobert, Judith A; Embacher, Rebecca; Mester, Jessica L; Frazier, Thomas W; Eng, Charis

2014-01-01

Unlike some other childhood neurodevelopmental disorders, no diagnostic biochemical marker has been identified in all individuals with an autism spectrum disorder (ASD). This deficit likely results from genetic heterogeneity among the population. Therefore, we evaluated a subset of individuals with ASDs, specifically, individuals with or without macrocephaly in the presence or absence of PTEN mutations. We sought to determine if amino or organic acid markers could be used to identify individuals with ASDs with or without macrocephaly in the presence or absence of PTEN mutations, and to establish the degree of macrocephaly in individuals with ASDs and PTEN mutation. Urine, blood and occipital–frontal circumference (OFC) measurements were collected from 69 individuals meeting DSM-IV-TR criteria. Urine and plasma samples were subjected to amino and organic acid analyses. PTEN was Sanger-sequenced from germline genomic DNA. Germline PTEN mutations were identified in 27% (6/22) of the macrocephalic ASD population. All six PTEN mutation-positive individuals were macrocephalic with average OFC+4.35 standard deviations (SDs) above the mean. No common biochemical abnormalities were identified in macrocephalic ASD individuals with or without PTEN mutations. In contrast, among the collective ASD population, elevation of urine aspartic acid (87% 54/62), plasma taurine (69% 46/67) and reduction of plasma cystine (72% 46/64) were observed. PTEN sequencing should be carried out for all individuals with ASDs and macrocephaly with OFC ≥2SDs above the mean. A proportion of individuals with ASDs may have an underlying disorder in sulfur amino acid metabolism. PMID:23695273

[Expression of PTEN in Myocardial Tissue in Coronary Heart Disease].

PubMed

Li, Xue-rong; He, Yong; Lei, Yu-jia; Qin, Xe-he; Wei, Qing-tao; Pan, Xin-min; Li, Li-juan; Zhang, Lin

2016-04-01

To observe the expression of phosphatase and tensin homology deleted on chromosome ten (PTEN) in myocardial tissue in patients with coronary heart disease, and explore the relevance between the expression of PTEN and the occurrence and development of coronary heart disease. A total of 16 death cases with pathological diagnosis of coronary heart disease were collected as experimental group, and 19 cases without myocardial lesions were selected as control group. The expression of PTEN protein and its mRNA were detected by immunohistochemistry and real-time fluorescence quantitative PCR respectively. The correlation between the expression of PTEN and the pathogenesis of coronary heart disease was analyzed. The expression of PTEN protein in myocardium in cases with coronary heart disease was significantly lower compared with the control group (P < 0.05). There was no statistical difference of the expression of PTEN mRNA between experimental and control group (P > 0.05). PTEN may be involved in the occurrence and development of coronary heart disease.

Conditional Deletion of Pten Causes Bronchiolar Hyperplasia

PubMed Central

Davé, Vrushank; Wert, Susan E.; Tanner, Tiffany; Thitoff, Angela R.; Loudy, Dave E.; Whitsett, Jeffrey A.

2008-01-01

Tumor suppressor phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is a lipid phosphatase that regulates multiple cellular processes including cell polarity, migration, proliferation, and carcinogenesis. In this work, we demonstrate that conditional deletion of Pten (PtenΔ/Δ) in the respiratory epithelial cells of the developing mouse lung caused epithelial cell proliferation and hyperplasia as early as 4 to 6 weeks of age. While bronchiolar cell differentiation was normal, as indicated by β-tubulin and FOXJ1 expression in ciliated cells and by CCSP expression in nonciliated cells, cell proliferation (detected by expression of Ki-67, phospho-histone-H3, and cyclin D1) was increased and associated with activation of the AKT/mTOR survival pathway. Deletion of Pten caused papillary epithelial hyperplasia characterized by a hypercellular epithelium lining papillae with fibrovascular cores that protruded into the airway lumens. Cell polarity, as assessed by subcellular localization of cadherin, β-catenin, and zonula occludens-1, was unaltered. PTEN is required for regulation of epithelial cell proliferation in the lung and for the maintenance of the normal simple columnar epithelium characteristics of bronchi and bronchioles. PMID:17921358

Conditional deletion of Pten causes bronchiolar hyperplasia.

PubMed

Davé, Vrushank; Wert, Susan E; Tanner, Tiffany; Thitoff, Angela R; Loudy, Dave E; Whitsett, Jeffrey A

2008-03-01

Tumor suppressor phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is a lipid phosphatase that regulates multiple cellular processes including cell polarity, migration, proliferation, and carcinogenesis. In this work, we demonstrate that conditional deletion of Pten (Pten(Delta/Delta)) in the respiratory epithelial cells of the developing mouse lung caused epithelial cell proliferation and hyperplasia as early as 4 to 6 weeks of age. While bronchiolar cell differentiation was normal, as indicated by beta-tubulin and FOXJ1 expression in ciliated cells and by CCSP expression in nonciliated cells, cell proliferation (detected by expression of Ki-67, phospho-histone-H3, and cyclin D1) was increased and associated with activation of the AKT/mTOR survival pathway. Deletion of Pten caused papillary epithelial hyperplasia characterized by a hypercellular epithelium lining papillae with fibrovascular cores that protruded into the airway lumens. Cell polarity, as assessed by subcellular localization of cadherin, beta-catenin, and zonula occludens-1, was unaltered. PTEN is required for regulation of epithelial cell proliferation in the lung and for the maintenance of the normal simple columnar epithelium characteristics of bronchi and bronchioles.

Inhibition of Mycobacterial Infection by the Tumor Suppressor PTEN*

PubMed Central

Huang, Guochang; Redelman-Sidi, Gil; Rosen, Neal; Glickman, Michael S.; Jiang, Xuejun

2012-01-01

The tumor suppressor PTEN is a lipid phosphatase that is frequently mutated in various human cancers. PTEN suppresses tumor cell proliferation, survival, and growth mainly by inhibiting the PI3K-Akt signaling pathway through dephosphorylation of phosphatidylinositol 3,4,5-triphosphate. In addition to it role in tumor suppression, the PTEN-PI3K pathway controls many cellular functions, some of which may be important for cellular resistance to infection. Currently, the intersection between tumorigenic signaling pathways and cellular susceptibility to infection is not well defined. In this study we report that PTEN signaling regulates infection of both noncancerous and cancerous cells by multiple intracellular mycobacterial pathogens and that pharmacological modulation of PTEN signaling can affect mycobacterial infection. We found that PTEN deficiency renders multiple types of cells hyper-susceptible to infection by Mycoplasma and Mycobacterium bovis Bacillus Calmette-Guérin (BCG). The lipid phosphatase activity of PTEN is required for attenuating infection. Furthermore, we found mycobacterial infection activates host cell Akt phosphorylation, and pharmacological inhibition of Akt or PI3K activity reduced levels of intracellular infection. Intriguingly, inhibition of mTOR, one of the downstream components of the Akt signaling and a promising cancer therapeutic target, also lowered intracellular Bacillus Calmette-Guérin levels in mammary epithelial cancer MCF-7 cells. These findings demonstrate a critical role of PTEN-regulated pathways in pathogen infection. The relationship of PTEN-PI3K-Akt mTOR status and susceptibility to mycobacterial infection suggests that the interaction of mycobacterial pathogens with cancer cells may be influenced by genetic alterations in the tumor cells. PMID:22613768

Physical Foundations of PTEN/Phosphoinositide Interaction

NASA Astrophysics Data System (ADS)

Gericke, Arne; Jiang, Zhiping; Redfern, Roberta E.; Kooijman, Edgar E.; Ross, Alonzo H.

2009-03-01

Phosphoinositides act as signaling molecules by recruiting critical effectors to specific subcellular membranes to regulate cell proliferation, apoptosis and cytoskeletal reorganization, which requires a tight regulation of phosphoinositide generation and turnover as well as a high degree of compartmentalization. PTEN is a phosphatase specific for the 3 position of the phosophoinositide ring that is deleted or mutated in many different disease states. PTEN association with membranes requires the interaction of its C2 domain with phosphatidylserine and the interaction of its N-terminal end with phosphatidylinositol-4,5-bisphophate (PI(4,5)P2). We have investigated PTEN/PI(4,5)P2 interaction and found that Lys13 is crucial for the observed binding. We also found that the presence of cholesterol enhances PTEN binding to mixed PI(4,5)P2/POPC vesicles. Fluorescence microscopy experiments utilizing GUVs yielded results consistent with enhanced phosphoinositide domain formation in the presence of cholesterol. These experiments were accompanied by zeta potential measurements and solid state MAS ^31P-NMR experiments aimed at investigating the ionization behavior of phosphoinositides.

Modulation of liver regeneration via myeloid PTEN deficiency

PubMed Central

Ma, Wen-Tao; Jia, Yan-Jie; Liu, Qing-Zhi; Yang, Yan-Qing; Yang, Jing-Bo; Zhao, Zhi-Bin; Yang, Zhen-Ye; Shi, Qing-Hua; Ma, Hong-Di; Gershwin, M Eric; Lian, Zhe-Xiong

2017-01-01

Molecular mechanisms that modulate liver regeneration are of critical importance for a number of hepatic disorders. Kupffer cells and natural killer (NK) cells are two cell subsets indispensable for liver regeneration. We have focused on these two populations and, in particular, the interplay between them. Importantly, we demonstrate that deletion of the myeloid phosphatase and tensin homolog on chromosome 10 (PTEN) leading to an M2-like polarization of Kupffer cells, which results in decreased activation of NK cells. In addition, PTEN-deficient Kupffer cells secrete additional factors that facilitate the proliferation of hepatocytes. In conclusion, PTEN is critical for inhibiting M2-like polarization of Kupffer cells after partial hepatectomy, resulting in NK cell activation and thus the inhibition of liver regeneration. Furthermore, PTEN reduces growth factor secretion by Kupffer cells. Our results suggest that targeting PTEN on Kupffer cells may be useful in altering liver regeneration in patients undergoing liver resection. PMID:28542148

Cutting Edge: Differential Regulation of PTEN by TCR, Akt, and FoxO1 Controls CD4+ T Cell Fate Decisions.

PubMed

Hawse, William F; Sheehan, Robert P; Miskov-Zivanov, Natasa; Menk, Ashley V; Kane, Lawrence P; Faeder, James R; Morel, Penelope A

2015-05-15

Signaling via the Akt/mammalian target of rapamycin pathway influences CD4(+) T cell differentiation; low levels favor regulatory T cell induction and high levels favor Th induction. Although the lipid phosphatase phosphatase and tensin homolog (PTEN) suppresses Akt activity, the control of PTEN activity is poorly studied in T cells. In this study, we identify multiple mechanisms that regulate PTEN expression. During Th induction, PTEN function is suppressed via lower mRNA levels, lower protein levels, and an increase in C-terminal phosphorylation. Conversely, during regulatory T cell induction, PTEN function is maintained through the stabilization of PTEN mRNA transcription and sustained protein levels. We demonstrate that differential Akt/mammalian target of rapamycin signaling regulates PTEN transcription via the FoxO1 transcription factor. A mathematical model that includes multiple modes of PTEN regulation recapitulates our experimental findings and demonstrates how several feedback loops determine differentiation outcomes. Collectively, this work provides novel mechanistic insights into how differential regulation of PTEN controls alternate CD4(+) T cell fate outcomes. Copyright © 2015 by The American Association of Immunologists, Inc.

Immune dysregulation in patients with PTEN hamartoma tumor syndrome: Analysis of FOXP3 regulatory T cells.

PubMed

Chen, Hannah H; Händel, Norman; Ngeow, Joanne; Muller, James; Hühn, Michael; Yang, Huei-Ting; Heindl, Mario; Berbers, Roos-Marijn; Hegazy, Ahmed N; Kionke, Janina; Yehia, Lamis; Sack, Ulrich; Bläser, Frank; Rensing-Ehl, Anne; Reifenberger, Julia; Keith, Julia; Travis, Simon; Merkenschlager, Andreas; Kiess, Wieland; Wittekind, Christian; Walker, Lisa; Ehl, Stephan; Aretz, Stefan; Dustin, Michael L; Eng, Charis; Powrie, Fiona; Uhlig, Holm H

2017-02-01

Patients with heterozygous germline mutations in phosphatase and tensin homolog deleted on chromosome 10 (PTEN) experience autoimmunity and lymphoid hyperplasia. Because regulation of the phosphoinositide 3-kinase (PI3K) pathway is critical for maintaining regulatory T (Treg) cell functions, we investigate Treg cells in patients with heterozygous germline PTEN mutations (PTEN hamartoma tumor syndrome [PHTS]). Patients with PHTS were assessed for immunologic conditions, lymphocyte subsets, forkhead box P3 (FOXP3) + Treg cell levels, and phenotype. To determine the functional importance of phosphatases that control the PI3K pathway, we assessed Treg cell induction in vitro, mitochondrial depolarization, and recruitment of PTEN to the immunologic synapse. Autoimmunity and peripheral lymphoid hyperplasia were found in 43% of 79 patients with PHTS. Immune dysregulation in patients with PHTS included lymphopenia, CD4 + T-cell reduction, and changes in T- and B-cell subsets. Although total CD4 + FOXP3 + Treg cell numbers are reduced, frequencies are maintained in the blood and intestine. Despite pathogenic PTEN mutations, the FOXP3 + T cells are phenotypically normal. We show that the phosphatase PH domain leucine-rich repeat protein phosphatase (PHLPP) downstream of PTEN is highly expressed in normal human Treg cells and provides complementary phosphatase activity. PHLPP is indispensable for the differentiation of induced Treg cells in vitro and Treg cell mitochondrial fitness. PTEN and PHLPP form a phosphatase network that is polarized at the immunologic synapse. Heterozygous loss of function of PTEN in human subjects has a significant effect on T- and B-cell immunity. Assembly of the PTEN-PHLPP phosphatase network allows coordinated phosphatase activities at the site of T-cell receptor activation, which is important for limiting PI3K hyperactivation in Treg cells despite PTEN haploinsufficiency. Copyright © 2016 The Authors. Published by Elsevier Inc. All rights

PTEN genomic deletion predicts prostate cancer recurrence and is associated with low AR expression and transcriptional activity

PubMed Central

2012-01-01

Background Prostate cancer (PCa), a leading cause of cancer death in North American men, displays a broad range of clinical outcome from relatively indolent to lethal metastatic disease. Several genomic alterations have been identified in PCa which may serve as predictors of progression. PTEN, (10q23.3), is a negative regulator of the phosphatidylinositol 3-kinase (PIK3)/AKT survival pathway and a tumor suppressor frequently deleted in PCa. The androgen receptor (AR) signalling pathway is known to play an important role in PCa and its blockade constitutes a commonly used treatment modality. In this study, we assessed the deletion status of PTEN along with AR expression levels in 43 primary PCa specimens with clinical follow-up. Methods Fluorescence In Situ Hybridization (FISH) was done on formalin fixed paraffin embedded (FFPE) PCa samples to examine the deletion status of PTEN. AR expression levels were determined using immunohistochemistry (IHC). Results Using FISH, we found 18 cases of PTEN deletion. Kaplan-Meier analysis showed an association with disease recurrence (P=0.03). Concurrently, IHC staining for AR found significantly lower levels of AR expression within those tumors deleted for PTEN (P<0.05). To validate these observations we interrogated a copy number alteration and gene expression profiling dataset of 64 PCa samples, 17 of which were PTEN deleted. We confirmed the predictive value of PTEN deletion in disease recurrence (P=0.03). PTEN deletion was also linked to diminished expression of PTEN (P<0.01) and AR (P=0.02). Furthermore, gene set enrichment analysis revealed a diminished expression of genes downstream of AR signalling in PTEN deleted tumors. Conclusions Altogether, our data suggest that PTEN deleted tumors expressing low levels of AR may represent a worse prognostic subset of PCa establishing a challenge for therapeutic management. PMID:23171135

Balancing Proliferation and Connectivity in PTEN-associated Autism Spectrum Disorder.

PubMed

Tilot, Amanda K; Frazier, Thomas W; Eng, Charis

2015-07-01

Germline mutations in PTEN, which encodes a widely expressed phosphatase, was mapped to 10q23 and identified as the susceptibility gene for Cowden syndrome, characterized by macrocephaly and high risks of breast, thyroid, and other cancers. The phenotypic spectrum of PTEN mutations expanded to include autism with macrocephaly only 10 years ago. Neurological studies of patients with PTEN-associated autism spectrum disorder (ASD) show increases in cortical white matter and a distinctive cognitive profile, including delayed language development with poor working memory and processing speed. Once a germline PTEN mutation is found, and a diagnosis of phosphatase and tensin homolog (PTEN) hamartoma tumor syndrome made, the clinical outlook broadens to include higher lifetime risks for multiple cancers, beginning in childhood with thyroid cancer. First described as a tumor suppressor, PTEN is a major negative regulator of the phosphatidylinositol 3-kinase/protein kinase B/mammalian target of rapamycin (mTOR) signaling pathway-controlling growth, protein synthesis, and proliferation. This canonical function combines with less well-understood mechanisms to influence synaptic plasticity and neuronal cytoarchitecture. Several excellent mouse models of Pten loss or dysfunction link these neural functions to autism-like behavioral abnormalities, such as altered sociability, repetitive behaviors, and phenotypes like anxiety that are often associated with ASD in humans. These models also show the promise of mTOR inhibitors as therapeutic agents capable of reversing phenotypes ranging from overgrowth to low social behavior. Based on these findings, therapeutic options for patients with PTEN hamartoma tumor syndrome and ASD are coming into view, even as new discoveries in PTEN biology add complexity to our understanding of this master regulator.

Tissue transglutaminase regulates focal adhesion kinase/AKT activation by modulating PTEN expression in pancreatic cancer cells.

PubMed

Verma, Amit; Guha, Sushovan; Wang, Huamin; Fok, Jansina Y; Koul, Dimpy; Abbruzzese, James; Mehta, Kapil

2008-04-01

Pancreatic ductal adenocarcinoma (PDAC) progresses rapidly and exhibits profound resistance to treatment. We recently reported that a great majority of PDAC tumors and tumor cell lines express elevated levels of tissue transglutaminase (TG2). Here, we provide first evidence that TG2 expression in PDAC cells results in constitutive activation of focal adhesion kinase/AKT by modulating the expression of the tumor suppressor phosphatase PTEN. Using PDAC cell lines, we determined the effect of TG2 overexpression on PTEN stability and functions. We confirmed the correlation between TG2 expression and PTEN levels in a few (n=51) PDAC tumor samples. We observed that expression of TG2 is inversely correlated with PTEN expression in PDAC cells. Ectopic expression of TG2 inhibited PTEN phosphorylation and promoted its degradation by ubiquitin-proteasomal pathway. Conversely, down-regulation of TG2 by small interfering RNA up-regulated PTEN expression. Clinical relevance of these results was evident in an athymic nude mouse model where down-regulation of endogenous TG2 caused a significant retardation in PDAC xenograft growth. Importantly, the analysis of 51 tumor samples from patients with stage II PDAC revealed that overexpression of TG2 was associated with loss of PTEN expression (P=0.023; odds ratio, 4.1). In multivariate analysis, TG2-mediated loss of PTEN was a prognostic factor for overall survival in patients with stage II pancreatic ductal carcinoma independent of tumor stage/lymph node status and tumor differentiation (P=0.01). TG2 expression in PDAC promotes degradation of PTEN by ubiquitin-proteasomal pathway and results in constitutive activation of focal adhesion kinase/AKT cell survival signaling.

PTEN regulation of local and long-range connections in mouse auditory cortex

PubMed Central

Xiong, Qiaojie; Oviedo, Hysell V; Trotman, Lloyd C; Zador, Anthony M

2012-01-01

Autism Spectrum Disorders (ASDs) are highly heritable developmental disorders caused by a heterogeneous collection of genetic lesions. Here we use a mouse model to study the effect on cortical connectivity of disrupting the ASD candidate gene PTEN. Through Cre-mediated recombination we conditionally knocked out PTEN expression in a subset of auditory cortical neurons. Analysis of long range connectivity using channelrhodopsin-2 (ChR2) revealed that the strength of synaptic inputs from both the contralateral auditory cortex and from the thalamus onto PTEN-cko neurons was enhanced compared with nearby neurons with normal PTEN expression. Laser scanning photostimulation (LSPS) showed that local inputs onto PTEN-cko neurons in the auditory cortex were similarly enhanced. The hyperconnectivity caused by PTEN-cko could be blocked by rapamycin, a specific inhibitor of the PTEN downstream molecule mTORC1. Together our results suggest that local and long-range hyperconnectivity may constitute a physiological basis for the effects of mutations in PTEN and possibly other ASD candidate genes. PMID:22302806

Adenovirus mediated homozygous endometrial epithelial Pten deletion results in aggressive endometrial carcinoma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Joshi, Ayesha; Ellenson, Lora Hedrick, E-mail: lora.ellenson@med.cornell.edu

2011-07-01

Pten is the most frequently mutated gene in uterine endometriod carcinoma (UEC) and its precursor complex atypical hyperplasia (CAH). Because the mutation frequency is similar in CAH and UEC, Pten mutations are thought to occur relatively early in endometrial tumorigenesis. Previous work from our laboratory using the Pten{sup +/-} mouse model has demonstrated somatic inactivation of the wild type allele of Pten in both CAH and UEC. In the present study, we injected adenoviruses expressing Cre into the uterine lumen of adult Pten floxed mice in an attempt to somatically delete both alleles of Pten specifically in the endometrium. Ourmore » results demonstrate that biallelic inactivation of Pten results in an increased incidence of carcinoma as compared to the Pten{sup +/-} mouse model. In addition, the carcinomas were more aggressive with extension beyond the uterus into adjacent tissues and were associated with decreased expression of nuclear ER{alpha} as compared to associated CAH. Primary cultures of epithelial and stromal cells were prepared from uteri of Pten floxed mice and Pten was deleted in vitro using Cre expressing adenovirus. Pten deletion was evident in both the epithelial and stromal cells and the treatment of the primary cultures with estrogen had different effects on Akt activation as well as Cyclin D3 expression in the two purified components. This study demonstrates that somatic biallelic inactivation of Pten in endometrial epithelium in vivo results in an increased incidence and aggressiveness of endometrial carcinoma compared to mice carrying a germline deletion of one allele and provides an important in vivo and in vitro model system for understanding the genetic underpinnings of endometrial carcinoma.« less

The Smad4/PTEN Expression Pattern Predicts Clinical Outcomes in Colorectal Adenocarcinoma

PubMed Central

Chung, Yumin; Wi, Young Chan; Kim, Yeseul; Bang, Seong Sik; Yang, Jung-Ho; Jang, Kiseok; Min, Kyueng-Whan; Paik, Seung Sam

2018-01-01

Background Smad4 and PTEN are prognostic indicators for various tumor types. Smad4 regulates tumor suppression, whereas PTEN inhibits cell proliferation. We analyzed and compared the performance of Smad4 and PTEN for predicting the prognosis of patients with colorectal adenocarcinoma. Methods Combined expression patterns based on Smad4+/– and PTEN+/– status were evaluated by immunostaining using a tissue microarray of colorectal adenocarcinoma. The relationships between the protein expression and clinicopathological variables were analyzed. Results Smad4–/PTEN– status was most frequently observed in metastatic adenocarcinoma, followed by primary adenocarcinoma and tubular adenoma (p<.001). When Smad4–/PTEN– and Smad4+/PTEN+ groups were compared, Smad4–/PTEN– status was associated with high N stage (p=.018) and defective mismatch repair proteins (p=.006). Significant differences in diseasefree survival and overall survival were observed among the three groups (Smad4+/PTEN+, Smad4–/PTEN+ or Smad4+/PTEN–, and Smad4–/PTEN–) (all p<.05). Conclusions Concurrent loss of Smad4 and PTEN may lead to more aggressive disease and poor prognosis in patients with colorectal adenocarcinoma compared to the loss of Smad4 or PTEN alone. PMID:29056035

PTEN inhibition prevents rat cortical neuron injury after hypoxia-ischemia.

PubMed

Zhao, J; Qu, Y; Wu, J; Cao, M; Ferriero, D M; Zhang, L; Mu, D

2013-05-15

Alterations in axon-dendrite polarity impair functional recovery in the developing CNS after hypoxia-ischemia (HI) injury. PTEN (phosphatase and tensin homolog deleted on chromosome 10) signaling pathway mediates the formation of neuronal polarity. However, its role in cerebral HI injury is not fully understood. In this study, we investigated the role of PTEN pathway in regulation of axon-dendrite polarity using an oxygen-glucose deprivation (OGD) model with rat cortical neurons. We found that the activity of PTEN and glycogen synthase kinase 3β (GSK-3β) was increased after OGD, along with the decrease of the activity in protein kinase B (Akt) and collapsin response mediator protein-2 (CRMP-2). Pretreatment with bpv, a potent inhibitor of PTEN, caused a decrease of the activity in PTEN and GSK-3β, and a significant increase of the activity in Akt and CRMP-2. Simultaneously, the morphological polarity of neurons was maintained and neuronal apoptosis was reduced. Moreover, inhibition of PTEN rescued vesicle recycling in axons. These findings suggested that the PTEN/Akt/GSK-3β/CRMP-2 pathway is involved in the regulation of axon-dendrite polarity, providing a novel route for protecting neurons following neonatal HI. Copyright © 2013 IBRO. Published by Elsevier Ltd. All rights reserved.

Fatty acids increase neuronal hypertrophy of Pten knockdown neurons

PubMed Central

Fricano, Catherine J.; DeSpenza, Tyrone; Frazel, Paul W.; Li, Meijie; O'Malley, A. James; Westbrook, Gary L.; Luikart, Bryan W.

2014-01-01

Phosphatase and tensin homolog (Pten) catalyzes the reverse reaction of PI3K by dephosphorylating PIP3 to PIP2. This negatively regulates downstream Akt/mTOR/S6 signaling resulting in decreased cellular growth and proliferation. Co-injection of a lentivirus knocking Pten down with a control lentivirus allows us to compare the effects of Pten knockdown between individual neurons within the same animal. We find that knockdown of Pten results in neuronal hypertrophy by 21 days post-injection. This neuronal hypertrophy is correlated with increased p-S6 and p-mTOR in individual neurons. We used this system to test whether an environmental factor that has been implicated in cellular hypertrophy could influence the severity of the Pten knockdown-induced hypertrophy. Implantation of mini-osmotic pumps delivering fatty acids results in increased neuronal hypertrophy and p-S6/p-mTOR staining. These hypertrophic effects were reversed in response to rapamycin treatment. However, we did not observe a similar increase in hypertrophy in response to dietary manipulations of fatty acids. Thus, we conclude that by driving growth signaling with fatty acids and knocking down a critical regulator of growth, Pten, we are able to observe an additive morphological phenotype of increased soma size mediated by the mTOR pathway. PMID:24795563

Phosphorylation-mediated PTEN conformational closure and deactivation revealed with protein semisynthesis

PubMed Central

Bolduc, David; Rahdar, Meghdad; Tu-Sekine, Becky; Sivakumaren, Sindhu Carmen; Raben, Daniel; Amzel, L Mario; Devreotes, Peter; Gabelli, Sandra B; Cole, Philip

2013-01-01

The tumor suppressor PIP3 phosphatase PTEN is phosphorylated on four clustered Ser/Thr on its C-terminal tail (aa 380–385) and these phosphorylations are proposed to induce a reduction in PTEN’s plasma membrane recruitment. How these phosphorylations affect the structure and enzymatic function of PTEN is poorly understood. To gain insight into the mechanistic basis of PTEN regulation by phosphorylation, we generated semisynthetic site-specifically tetra-phosphorylated PTEN using expressed protein ligation. By employing a combination of biophysical and enzymatic approaches, we have found that purified tail-phosphorylated PTEN relative to its unphosphorylated counterpart shows reduced catalytic activity and membrane affinity and undergoes conformational compaction likely involving an intramolecular interaction between its C-tail and the C2 domain. Our results suggest that there is a competition between membrane phospholipids and PTEN phospho-tail for binding to the C2 domain. These findings reveal a key aspect of PTEN’s regulation and suggest pharmacologic approaches for direct PTEN activation. DOI: http://dx.doi.org/10.7554/eLife.00691.001 PMID:23853711

PTEN regulation of local and long-range connections in mouse auditory cortex.

PubMed

Xiong, Qiaojie; Oviedo, Hysell V; Trotman, Lloyd C; Zador, Anthony M

2012-02-01

Autism spectrum disorders (ASDs) are highly heritable developmental disorders caused by a heterogeneous collection of genetic lesions. Here we use a mouse model to study the effect on cortical connectivity of disrupting the ASD candidate gene PTEN (phosphatase and tensin homolog deleted on chromosome 10). Through Cre-mediated recombination, we conditionally knocked out PTEN expression in a subset of auditory cortical neurons. Analysis of long-range connectivity using channelrhodopsin-2 revealed that the strength of synaptic inputs from both the contralateral auditory cortex and from the thalamus onto PTEN-cko neurons was enhanced compared with nearby neurons with normal PTEN expression. Laser-scanning photostimulation showed that local inputs onto PTEN-cko neurons in the auditory cortex were similarly enhanced. The hyperconnectivity caused by PTEN-cko could be blocked by rapamycin, a specific inhibitor of the PTEN downstream molecule mammalian target of rapamycin complex 1. Together, our results suggest that local and long-range hyperconnectivity may constitute a physiological basis for the effects of mutations in PTEN and possibly other ASD candidate genes.

Rapamycin prevents, but does not reverse, aberrant migration in Pten knockout neurons.

PubMed

Getz, Stephanie A; DeSpenza, Tyrone; Li, Meijie; Luikart, Bryan W

2016-09-01

Phosphatase and tensin homolog (PTEN) is a major negative regulator of the Akt/mammalian target of rapamycin (MTOR) pathway. Mutations in PTEN have been found in a subset of individuals with autism and macrocephaly. Further, focal cortical dysplasia (FCD) has been observed in patients with PTEN mutations prompting us to examine the role of Pten in neuronal migration. The dentate gyrus of Pten(Flox/Flox) mice was injected with Cre- and non-Cre-expressing retroviral particles, which integrate into the dividing genome to birthdate cells. Control and Pten knockout (KO) cell position in the granule cell layer was quantified over time to reveal that Pten KO neurons exhibit an aberrant migratory phenotype beginning at 7.5days-post retroviral injection (DPI). We then assessed whether rapamycin, a mTor inhibitor, could prevent or reverse aberrant migration of granule cells. The preventative group received daily intraperitoneal (IP) injections of rapamycin from 3 to 14 DPI, before discrepancies in cell position have been established, while the reversal group received rapamycin afterward, from 14 to 24 DPI. We found that rapamycin prevented and reversed somal hypertrophy. However, rapamycin prevented, but did not reverse aberrant migration in Pten KO cells. We also find that altered migration occurs through mTorC1 and not mTorC2 activity. Together, these findings suggest a temporal window by which rapamycin can treat aberrant migration, and may have implications for the use of rapamycin to treat PTEN-mutation associated disorders. Mutations in phosphatase and tensin homolog (PTEN) have been linked to a subset of individuals with autism and macrocephaly, as well as Cowden Syndrome and focal cortical dysplasia. Pten loss leads to neuronal hypertrophy, but the role of Pten in neuronal migration is unclear. Here we have shown that loss of Pten leads to aberrant migration, which can be prevented but not reversed by treatment with rapamycin, a mTor inhibitor. These results are

The tumor suppressor PTEN has a critical role in antiviral innate immunity.

PubMed

Li, Shun; Zhu, Mingzhu; Pan, Ruangang; Fang, Ting; Cao, Yuan-Yuan; Chen, Shuliang; Zhao, Xiaolu; Lei, Cao-Qi; Guo, Lin; Chen, Yu; Li, Chun-Mei; Jokitalo, Eija; Yin, Yuxin; Shu, Hong-Bing; Guo, Deyin

2016-03-01

The gene encoding PTEN is one of the most frequently mutated tumor suppressor-encoding genes in human cancer. While PTEN's function in tumor suppression is well established, its relationship to anti-microbial immunity remains unknown. Here we found a pivotal role for PTEN in the induction of type I interferon, the hallmark of antiviral innate immunity, that was independent of the pathway of the kinases PI(3)K and Akt. PTEN controlled the import of IRF3, a master transcription factor responsible for IFN-β production, into the nucleus. We further identified a PTEN-controlled negative phosphorylation site at Ser97 of IRF3 and found that release from this negative regulation via the phosphatase activity of PTEN was essential for the activation of IRF3 and its import into the nucleus. Our study identifies crosstalk between PTEN and IRF3 in tumor suppression and innate immunity.

PTEN is a potent suppressor of small cell lung cancer.

PubMed

Cui, Min; Augert, Arnaud; Rongione, Michael; Conkrite, Karina; Parazzoli, Susan; Nikitin, Alexander Yu; Ingolia, Nicholas; MacPherson, David

2014-05-01

Small cell lung carcinoma (SCLC) is a highly metastatic tumor type with neuroendocrine features and a dismal prognosis. PTEN mutations and PIK3CA activating mutations have been reported in SCLC but the functional relevance of this pathway is unknown. The PTEN/PIK3CA pathway was interrogated using an AdenoCre-driven mouse model of SCLC harboring inactivated Rb and p53. Inactivation of one allele of PTEN in Rb/p53-deleted mice led to accelerated SCLC with frequent metastasis to the liver. In contrast with the high mutation burden reported in human SCLC, exome analyses revealed a low number of protein-altering mutations in mouse SCLC. Inactivation of both alleles of PTEN in the Rb/p53-deleted system led to nonmetastatic adenocarcinoma with neuroendocrine differentiation. This study reveals a critical role for the PTEN/PI3K pathway in both SCLC and lung adenocarcinoma and provides an ideal system to test the phosphoinositide 3-kinase (PI3K) pathway inhibitors as targeted therapy for subsets of patients with SCLC. The ability of PTEN inactivation to accelerate SCLC in a genetic mouse model suggests that targeting the PTEN pathway is a therapeutic option for a subset of human patients with SCLC. VISUAL OVERVIEW: http://mcr.aacrjournals.org/content/early/2014/04/28/1541-7786.MCR-13-0554/F1.large.jpg. ©2014 AACR.

BMP suppresses PTEN expression via RAS/ERK signaling.

PubMed

Beck, Stayce E; Carethers, John M

2007-08-01

Bone morphogenetic protein (BMP), a member of the transforming growth factor beta family, classically utilizes the SMAD signaling pathway for its growth suppressive effects,and loss of this signaling cascade may accelerate cell growth. In the colon cancer predisposition syndrome Juvenile Polyposis, as well as in the late progression stages of nonsyndromic colorectal cancers, SMAD4 function is typically abrogated. Here, we utilized the SMAD4-null SW480 colon cancer cell line to examine BMPs effect on a potential target gene, PTEN, and how its expression might be regulated. Initial treatment of the SMAD4-null cells with BMP resulted in mild growth suppression, but with prolonged exposure to BMP, the cells become growth stimulatory, which coincided with observed decreases in transcription and translation of PTEN, and with corresponding increases in phospho-AKT protein levels. BMP-induced PTEN suppression was mediated via the RAS/ERK pathway, as pharmacologic inhibition of RAS/ERK, or interference with protein function in the cytosol by DN-RAS prevented BMP-induced growth promotion and changes in PTEN levels, as did treatment with noggin, a BMP ligand inhibitor. Thus, BMP downregulates PTEN via RAS/ERK in a SMAD4-null environment that contributes to cell growth, and constitutes a SMAD4-independent but BMP-responsive signaling pathway.

Planarian PTEN homologs regulate stem cells and regeneration through TOR signaling.

PubMed

Oviedo, Néstor J; Pearson, Bret J; Levin, Michael; Sánchez Alvarado, Alejandro

2008-01-01

We have identified two genes, Smed-PTEN-1 and Smed-PTEN-2, capable of regulating stem cell function in the planarian Schmidtea mediterranea. Both genes encode proteins homologous to the mammalian tumor suppressor, phosphatase and tensin homolog deleted on chromosome 10 (PTEN). Inactivation of Smed-PTEN-1 and -2 by RNA interference (RNAi) in planarians disrupts regeneration, and leads to abnormal outgrowths in both cut and uncut animals followed soon after by death (lysis). The resulting phenotype is characterized by hyperproliferation of neoblasts (planarian stem cells), tissue disorganization and a significant accumulation of postmitotic cells with impaired differentiation capacity. Further analyses revealed that rapamycin selectively prevented such accumulation without affecting the normal neoblast proliferation associated with physiological turnover and regeneration. In animals in which PTEN function is abrogated, we also detected a significant increase in the number of cells expressing the planarian Akt gene homolog (Smed-Akt). However, functional abrogation of Smed-Akt in Smed-PTEN RNAi-treated animals does not prevent cell overproliferation and lethality, indicating that functional abrogation of Smed-PTEN is sufficient to induce abnormal outgrowths. Altogether, our data reveal roles for PTEN in the regulation of planarian stem cells that are strikingly conserved to mammalian models. In addition, our results implicate this protein in the control of stem cell maintenance during the regeneration of complex structures in planarians.

Pten Knockdown in vivo Increases Excitatory Drive onto Dentate Granule Cells

PubMed Central

Luikart, Bryan W.; Schnell, Eric; Washburn, Eric K.; Bensen, AeSoon L.; Tovar, Kenneth R.; Westbrook, Gary L.

2011-01-01

Some cases of autism spectrum disorder (ASD) have mutations in the lipid phosphatase, Pten (phosphatase and tensin homolog on chromosome 10). Tissue specific deletion of Pten in the hippocampus and cortex of mice causes anatomical and behavioral abnormalities similar to human autism. However, the impact of reductions in Pten on synaptic and circuit function remains unexplored. We used in vivo stereotaxic injections of lentivirus expressing an shRNA to knockdown Pten in mouse neonatal and young adult dentate granule cells. We then assessed the morphology and synaptic physiology between two weeks and four months later. Confocal imaging of the hippocampus revealed a marked increase in granule cell size and an increase in dendritic spine density. The onset of morphological changes occurred earlier in neonatal mice than in young adults. We used whole-cell recordings from granule cells in acute slices to assess synaptic function following Pten knockdown. Consistent with the increase in dendritic spines, the frequency of excitatory miniature and spontaneous postsynaptic currents increased. However, there was little or no effect on inhibitory postsynaptic currents. Thus Pten knockdown results in an imbalance between excitatory and inhibitory synaptic activity. Because reductions in Pten affected mature granule cells as well as developing granule cells, we suggest that the disruption of circuit function by Pten hypofunction may be ongoing well beyond early development. PMID:21411674

Imbalanced PTEN and Phosphoinositide 3-kinase signaling impairs class switch recombination1

PubMed Central

Chen, Xiaomi; Dollin, Yonatan; Cambier, John C.; Wang, Jing H.

2015-01-01

Class switch recombination (CSR) generates isotype-switched antibodies with distinct effector functions. B cells express phosphatase and tensin homolog (PTEN) and multiple isoforms of class IA phosphoinositide 3-kinase (PI3K) catalytic subunits, including p110α and p110δ, whose roles in CSR remain unknown or controversial. Here, we demonstrate a direct effect of PTEN on CSR signaling by acute deletion of Pten specifically in mature B cells, thereby excluding the developmental impact of Pten deletion. We show that mature B cell-specific PTEN overexpression enhances CSR. More importantly, we establish a critical role of p110α in CSR. Furthermore, we identify a cooperative role of p110α and p110δ in suppressing CSR. Mechanistically, dysregulation of p110α or PTEN reversely affects activation-induced deaminase expression via modulating AKT activity. Thus, our study reveals that a signaling balance between PTEN and PI3K isoforms is essential to maintain normal CSR. PMID:26500350

PTEN in kidney cancer: A review and meta-analysis.

PubMed

Que, Wan-Cai; Qiu, Hong-Qiang; Cheng, Yu; Liu, Mao-Bai; Wu, Chao-Yang

2018-05-01

Kidney cancer is one of the most common cancers in the USA causing 14,400 deaths per year. The phosphatase and tensin homolog (PTEN) has been extensively documented as a tumor suppresser gene in cancer. However, there is unclear evidence for its clinicopathological and prognostic role in kidney cancer. A systematic review of literature assessing PTEN expression and clinical outcome in patients with kidney cancer. Web of Science, PubMed, Embase, and Chinese databases were searched for collecting for the eligible studies providing sufficient information. Pooled odds ratios (ORs) and hazard ratios (HRs) were respectively used to evaluate the association between PTEN levels and the clinicopathological features and clinical outcomes. A total of 35 studies enrolling 4532 patients were finally included in this study. For the survival outcome, the result suggested that shorter overall survival (OS) was correlated with low PTEN expression (HR = 0.57, 95% CIs: 0.45-0.74, P < 0.0001). The meta-analysis indicated a significantly increased risk of tumorigenesis in the PTEN low-level group relative to the control group (OR = 0.098, 95% CIs: 0.067-0.143, P < 0.001). Moreover, the results displayed the positive correlation between poorer differentiation (OR = 0.234, 95% CIs: 0.133-0.410, P < 0.001), distant metastasis (OR = 0.179, 95% CIs: 0.092-0.350, P = 0.001), lymph node metastasis (OR = 0.252, 95% CIs: 0.113-0.563, P < 0.001), advanced clinical stages (OR = 0.233, 95% CI: 0.133, 0.406, P < 0.001) and low PTEN expression. Finally, there was no obvious publication bias found in the meta-analysis. Decreased PTEN was associated with poorer survival outcomes of patients with kidney cancer and PTEN acts as a tumor suppressor in tumorigeneses and progression in kidney cancer. Copyright © 2018. Published by Elsevier B.V.

Expression patterns and role of PTEN in rat peripheral nerve development and injury.

PubMed

Chen, Hui; Xiang, Jianping; Wu, Junxia; He, Bo; Lin, Tao; Zhu, Qingtang; Liu, Xiaolin; Zheng, Canbin

2018-05-29

Studies have suggested that phosphatase and tensin homolog (PTEN) plays an important role in neuroprotection and neuronal regeneration. To better understand the potential role of PTEN with respect to peripheral nerve development and injury, we investigated the expression pattern of PTEN at different stages of rat peripheral nerve development and injury and subsequently assessed the effect of pharmacological inhibition of PTEN using bpV(pic) on axonal regeneration in a rat sciatic nerve crush injury model. During the early stages of development, PTEN exhibits low expression in neuronal cell bodies and axons. From embryonic day (E) 18.5 and postnatal day (P)5 to adult, PTEN protein becomes more detectable, with high expression in the dorsal root ganglia (DRG) and axons. PTEN expression is inhibited in peripheral nerves, preceding myelination during neuronal development and remyelination after acute nerve injury. Low PTEN expression after nerve injury promotes Akt/mammalian target of rapamycin (mTOR) signaling pathway activity. In vivo pharmacological inhibition of PTEN using bpV(pic) promoted axonal regrowth, increased the number of myelinated nerve fibers, improved locomotive recovery and enhanced the amplitude response and nerve conduction velocity following stimulation in a rat sciatic nerve crush injury model. Thus, we suggest that PTEN may play potential roles in peripheral nerve development and regeneration and that inhibition of PTEN expression is beneficial for nerve regeneration and functional recovery after peripheral nerve injury. Copyright © 2018 Elsevier B.V. All rights reserved.

The mechanism involved in the loss of PTEN expression in NSCLC tumor cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Li, Gang; Zhao, Jingfeng; Peng, Xianjing

2012-02-17

Highlights: Black-Right-Pointing-Pointer Radiation stimulates PTEN reexpression in NSCLC independent of p53 activation. Black-Right-Pointing-Pointer PTEN reexpression is mediated by miR-29b overexpression. Black-Right-Pointing-Pointer miR-29b regulates Dnmts expression in NSCLC tumor cells. Black-Right-Pointing-Pointer Target therapy could be established by overexpressing miR-29b expression. -- Abstract: Loss of PTEN expression is observed in most non-small cell lung cancers (NSCLC). However, the mechanism by which PTEN expression is regulated in NSCLC has not been fully elucidated. In this study, we investigated the role of DNA methyltransferases (Dnmts), microRNA-29b (miR-29b), and anti-miR-29b inhibitor in PTEN promoter methylation and PTEN gene expression in H358 NSCLC cells in vitromore » and in vivo. PTEN mRNA was measured by RT-PCR. PTEN and Dnmts protein levels were measured by Western blot. miR-29b expression was detected by Northern blot. A xenograft H358 tumor mouse model was established by subcutaneously inoculating H358 cells into the right hind limbs of nude mice. We found that radiation induced cell apoptosis and hypomethylation in PTEN promoter, PTEN and miR-29b expression, and downregulation of Dnmt1, 3a and 3b expression in H358 tumor cells. The effect of radiation on gene expression and apoptosis was blocked by anti-miR-29b inhibitor. In the xenograft H358 tumor model, anti-miR-29b inhibitor reversed radiation-induced tumor growth delay, PTEN reexpression and downregulation of Dnmts expression. Our study suggested that miR-29b is an upstream molecule of PTEN. miR-29b regulates PTEN gene expression through downregulating Dnmts expression and subsequently induces hypomethylation in PTEN promoter. Targeting therapy could be established in NSCLC by upregulating miR-29b expression.« less

Cell-type specific roles for PTEN in establishing a functional retinal architecture.

PubMed

Cantrup, Robert; Dixit, Rajiv; Palmesino, Elena; Bonfield, Stephan; Shaker, Tarek; Tachibana, Nobuhiko; Zinyk, Dawn; Dalesman, Sarah; Yamakawa, Kazuhiro; Stell, William K; Wong, Rachel O; Reese, Benjamin E; Kania, Artur; Sauvé, Yves; Schuurmans, Carol

2012-01-01

The retina has a unique three-dimensional architecture, the precise organization of which allows for complete sampling of the visual field. Along the radial or apicobasal axis, retinal neurons and their dendritic and axonal arbors are segregated into layers, while perpendicular to this axis, in the tangential plane, four of the six neuronal types form patterned cellular arrays, or mosaics. Currently, the molecular cues that control retinal cell positioning are not well-understood, especially those that operate in the tangential plane. Here we investigated the role of the PTEN phosphatase in establishing a functional retinal architecture. In the developing retina, PTEN was localized preferentially to ganglion, amacrine and horizontal cells, whose somata are distributed in mosaic patterns in the tangential plane. Generation of a retina-specific Pten knock-out resulted in retinal ganglion, amacrine and horizontal cell hypertrophy, and expansion of the inner plexiform layer. The spacing of Pten mutant mosaic populations was also aberrant, as were the arborization and fasciculation patterns of their processes, displaying cell type-specific defects in the radial and tangential dimensions. Irregular oscillatory potentials were also observed in Pten mutant electroretinograms, indicative of asynchronous amacrine cell firing. Furthermore, while Pten mutant RGC axons targeted appropriate brain regions, optokinetic spatial acuity was reduced in Pten mutant animals. Finally, while some features of the Pten mutant retina appeared similar to those reported in Dscam-mutant mice, PTEN expression and activity were normal in the absence of Dscam. We conclude that Pten regulates somal positioning and neurite arborization patterns of a subset of retinal cells that form mosaics, likely functioning independently of Dscam, at least during the embryonic period. Our findings thus reveal an unexpected level of cellular specificity for the multi-purpose phosphatase, and identify Pten as an

RNA interference mediated pten knock-down inhibit the formation of polycystic ovary.

PubMed

Ouyang, Jie-Xiu; Luo, Tao; Sun, Hui-Yun; Huang, Jian; Tang, Dan-Feng; Wu, Lei; Zheng, Yue-Hui; Zheng, Li-Ping

2013-08-01

Pten (phosphatase and tensin homolog deleted on chromosome 10), a kind of tumor suppressor gene, plays important roles in female reproductive system. But its expression and roles in the formation of polycystic ovaries are yet to be known. In this study, we constructed a rat model of PCOS using norethindrone and HCG injections and found the expressions of pten mRNA and PTEN protein increased significantly in the polycystic ovary tissue by immunohistochemistry, RT-PCR, and western blot. Furthermore, the results showed that in vivo ovaries could be effectively transfected by lentiviral vectors through the ovarian microinjection method and indicated that pten shRNA may inhibit the formation of polycystic ovaries by pten down-regulation. Our study provides new information regarding the role of PTEN in female reproductive disorders, such as polycystic ovary syndrome.

Expression of NF-κB and PTEN in osteosarcoma and its clinical significance

PubMed Central

Gong, Teng; Su, Xuetao; Xia, Qun; Wang, Jinggui; Kan, Shilian

2017-01-01

We investigated the role of nuclear factor-κB (NF-κB) and phosphatase and tensin homolog deleted in chromosome 10 (PTEN) in the pathogenesis of osteosarcoma and its relationship with prognosis. Immunohistochemical method was used to detect the expression of NF-κB and PTEN in osteosarcoma and adjacent tissues. RT-PCR was used to detect the expression of NF-κB and PTEN mRNA in osteosarcoma and adjacent tissues. Western blotting was used to detect the expression of NF-κB and PTEN in osteosarcoma and adjacent tissues and compare their differences. The expression of NF-κB and PTEN was detected in osteosarcoma and adjacent tissues. The positive rate of NF-κB was 75.3 and 32.9%, respectively; while the positive rate of PTEN was 67.1 and 90.4%, respectively. The positive expression of NF-κB and PTEN was statistically significant. There was a negative correlation between NF-κB and PTEN expression (r=−0.502, p<0.05). The positive and negative expression of NF-κB and PTEN was statistically significant for the five-year survival (p<0.05). At gene and protein level, osteosarcoma tissues had higher expression of NF-κB, and lower expression of PTEN, which was significantly different from the adjacent tissues. In osteosarcoma, NF-κB is highly expressed, but PTEN is expressed at low level, and the two are negatively correlated. This is of great significance for the early diagnosis of osteosarcoma and prognosis. PMID:29151913

A comprehensive functional analysis of PTEN mutations: implications in tumor- and autism-related syndromes.

PubMed

Rodríguez-Escudero, Isabel; Oliver, María D; Andrés-Pons, Amparo; Molina, María; Cid, Víctor J; Pulido, Rafael

2011-11-01

The PTEN (phosphatase and tensin homolog) phosphatase is unique in mammals in terms of its tumor suppressor activity, exerted by dephosphorylation of the lipid second messenger PIP(3) (phosphatidylinositol 3,4,5-trisphosphate), which activates the phosphoinositide 3-kinase/Akt/mTOR (mammalian target of rapamycin) oncogenic pathway. Loss-of-function mutations in the PTEN gene are frequent in human cancer and in the germline of patients with PTEN hamartoma tumor-related syndromes (PHTSs). In addition, PTEN is mutated in patients with autism spectrum disorders (ASDs), although no functional information on these mutations is available. Here, we report a comprehensive in vivo functional analysis of human PTEN using a heterologous yeast reconstitution system. Ala-scanning mutagenesis at the catalytic loops of PTEN outlined the critical role of residues within the P-catalytic loop for PIP(3) phosphatase activity in vivo. PTEN mutations that mimic the P-catalytic loop of mammalian PTEN-like proteins (TPTE, TPIP, tensins and auxilins) affected PTEN function variably, whereas tumor- or PHTS-associated mutations targeting the PTEN P-loop produced complete loss of function. Conversely, Ala-substitutions, as well as tumor-related mutations at the WPD- and TI-catalytic loops, displayed partial activity in many cases. Interestingly, a tumor-related D92N mutation was partially active, supporting the notion that the PTEN Asp92 residue might not function as the catalytic general acid. The analysis of a panel of ASD-associated hereditary PTEN mutations revealed that most of them did not substantially abrogate PTEN activity in vivo, whereas most of PHTS-associated mutations did. Our findings reveal distinctive functional patterns among PTEN mutations found in tumors and in the germline of PHTS and ASD patients, which could be relevant for therapy.

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meng, Zhen; Department of Oral & Maxillofacial Surgery, Peking University School and Hospital of Stomatology, 22 Zhongguancun Avenue South, Haidian District, Beijing 100081; Gan, Ye-Hua, E-mail: kqyehuagan@bjmu.edu.cn

2015-05-01

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

PTEN in the maintenance of genome integrity: From DNA replication to chromosome segregation.

PubMed

Hou, Sheng-Qi; Ouyang, Meng; Brandmaier, Andrew; Hao, Hongbo; Shen, Wen H

2017-10-01

Faithful DNA replication and accurate chromosome segregation are the key machineries of genetic transmission. Disruption of these processes represents a hallmark of cancer and often results from loss of tumor suppressors. PTEN is an important tumor suppressor that is frequently mutated or deleted in human cancer. Loss of PTEN has been associated with aneuploidy and poor prognosis in cancer patients. In mice, Pten deletion or mutation drives genomic instability and tumor development. PTEN deficiency induces DNA replication stress, confers stress tolerance, and disrupts mitotic spindle architecture, leading to accumulation of structural and numerical chromosome instability. Therefore, PTEN guards the genome by controlling multiple processes of chromosome inheritance. Here, we summarize current understanding of the PTEN function in promoting high-fidelity transmission of genetic information. We also discuss the PTEN pathways of genome maintenance and highlight potential targets for cancer treatment. © 2017 WILEY Periodicals, Inc.

PTEN Is a Negative Regulator of NK Cell Cytolytic Function

PubMed Central

Briercheck, Edward L.; Trotta, Rossana; Chen, Li; Hartlage, Alex S.; Cole, Jordan P.; Cole, Tyler D.; Mao, Charlene; Banerjee, Pinaki P.; Hsu, Hsiang-Ting; Mace, Emily M.; Ciarlariello, David; Mundy-Bosse, Bethany L.; Garcia-Cao, Isabel; Scoville, Steven D.; Yu, Lianbo; Pilarski, Robert; Carson, William E.; Leone, Gustavo; Pandolfi, Pier Paolo; Yu, Jianhua; Orange, Jordan S.; Caligiuri, Michael A.

2015-01-01

Human NK cells are characterized by their ability to initiate an immediate and direct cytolytic response to virally infected or malignantly transformed cells. Within human peripheral blood, the more mature CD56dim NK cell efficiently kills malignant targets at rest, whereas the less mature CD56bright NK cells cannot. In this study, we show that resting CD56bright NK cells express significantly more phosphatase and tensin homolog deleted on chromosome 10 (PTEN) protein when compared with CD56dim NK cells. Consistent with this, forced overexpression of PTEN in NK cells resulted in decreased cytolytic activity, and loss of PTEN in CD56bright NK cells resulted in elevated cytolytic activity. Comparable studies in mice showed PTEN overexpression did not alter NK cell development or NK cell–activating and inhibitory receptor expression yet, as in humans, did decrease expression of downstream NK activation targets MAPK and AKT during early cytolysis of tumor target cells. Confocal microscopy revealed that PTEN overexpression disrupts the NK cell’s ability to organize immunological synapse components including decreases in actin accumulation, polarization of the microtubule organizing center, and the convergence of cytolytic granules. In summary, our data suggest that PTEN normally works to limit the NK cell’s PI3K/AKT and MAPK pathway activation and the consequent mobilization of cytolytic mediators toward the target cell and suggest that PTEN is among the active regulatory components prior to human NK cells transitioning from the noncytolytic CD56bright NK cell to the cytolytic CD56dim NK cells. PMID:25595786

Endogenous S-sulfhydration of PTEN helps protect against modification by nitric oxide

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ohno, Kazuki; Okuda, Kosaku; Uehara, Takashi, E-mail: uehara@pharm.okayama-u.ac.jp

2015-01-02

Highlights: • PTEN is S-sulfhydrated endogenously in SH-SY5Y human neuroblastoma cells. • Preventing this modification by knocking down CBS renders PTEN sensitive to NO. • pAkt levels are increased significantly in CBS siRNA-transfected cells. • H{sub 2}S functions as an endogenous regulator of PTEN in neuronal cells. - Abstract: Hydrogen sulfide (H{sub 2}S) is a gaseous regulatory factor produced by several enzymes, and plays a pivotal role in processes such as proliferation or vasodilation. Recent reports demonstrated the physiological and pathophysiological functions of H{sub 2}S in neurons. PTEN is a target of nitric oxide (NO) or hydrogen peroxide, and themore » oxidative modification of cysteine (Cys) residue(s) attenuates its enzymatic activity. In the present study, we assessed the effect of H{sub 2}S on the direct modification of PTEN and the resulting downstream signaling. A modified biotin switch assay in SH-SY5Y human neuroblastoma cells revealed that PTEN is S-sulfhydrated endogenously. Subsequently, site-directed mutagenesis demonstrated that both Cys71 and Cys124 in PTEN are targets for S-sulfhydration. Further, the knockdown of cystathionine β-synthetase (CBS) using siRNA decreased this modification in a manner that was correlated to amount of H{sub 2}S. PTEN was more sensitive to NO under these conditions. These results suggest that the endogenous S-sulfhydration of PTEN via CBS/H{sub 2}S plays a role in preventing the S-nitrosylation that would inhibition its enzymatic activity under physiological conditions.« less

Role of PTEN in the Tumor Microenvironment

DTIC Science & Technology

2008-06-01

van Diest PJ. (2008). Hexokinase III, cyclin A and galectin - 3 are overexpressed in malignant follicular thyroid nodules. Clin Endocrinol (Oxf) 2...Annual 3 . DATES COVERED (From - To) 15 May 2007 – 14 May 2008 4. TITLE AND SUBTITLE Role of PTEN in the Tumor Microenvironment 5a. CONTRACT NUMBER...1998) that impacts several signaling pathways, including phosphoinositide 3 -kinase (PI3K), and Ras-MAPK-Erk1/2 signaling pathways. Pten inactivation

PTEN expression and function in adult cancer stem cells and prospects for therapeutic targeting.

PubMed

Ciuffreda, Ludovica; Falcone, Italia; Incani, Ursula Cesta; Del Curatolo, Anais; Conciatori, Fabiana; Matteoni, Silvia; Vari, Sabrina; Vaccaro, Vanja; Cognetti, Francesco; Milella, Michele

2014-09-01

Phosphatase and tensin homolog deleted on chromosome ten (PTEN) is a non-redundant lipid phosphatase that restrains and fine tunes the phosphatidylinositol-3-kinase (PI3K) signaling pathway. PTEN is involved in inherited syndromes, which predispose to different types of cancers and is among the most frequently inactivated tumor suppressor genes in sporadic cancers. Indeed, loss of PTEN function occurs in a wide spectrum of human cancers through a variety of mechanisms, including mutations, deletions, transcriptional silencing, or protein instability. PTEN prevents tumorigenesis through multiple mechanisms and regulates a plethora of cellular processes, including survival, proliferation, energy metabolism and cellular architecture. Moreover, recent studies have demonstrated that PTEN is able to exit, exist, and function outside the cell, allowing for inhibition of the PI3K pathway in neighboring cells in a paracrine fashion. Most recently, studies have shown that PTEN is also critical for stem cell maintenance and that PTEN loss can lead to the emergence and proliferation of cancer stem cell (CSC) clones. Depending on the cellular and tissue context of origin, PTEN deletion may result in increased self-renewal capacity or normal stem cell exhaustion and PTEN-defìcient stem and progenitor cells have been reported in prostate, lung, intestinal, and pancreatic tissues before tumor formation; moreover, reversible or irreversible PTEN loss is frequently observed in CSC from a variety of solid and hematologic malignancies, where it may contribute to the functional phenotype of CSC. In this review, we will focus on the role of PTEN expression and function and downstream pathway activation in cancer stem cell biology and regulation of the tumorigenic potential; the emerging role of PTEN in mediating the crosstalk between the PI3K and MAPK pathways will also be discussed, together with prospects for the therapeutic targeting of tumors lacking PTEN expression. Copyright �

PTEN, the Achilles' heel of myocardial ischaemia/reperfusion injury?

PubMed Central

Mocanu, M M; Yellon, D M

2007-01-01

Myocardial ischaemia/reperfusion injury leading to myocardial infarction is one of the most frequent causes of debilitation and death in man. Considerable research has been undertaken to investigate the possibility of reducing myocardial infarction and increasing cell survival by activating certain endogenous prosurvival signaling pathways. Thus, it has been established that the activation of the PI3K (Phosphoinositide-3 kinase)/Akt (Protein kinase B, PKB) signaling pathway is essential for protection against ischaemia/reperfusion injury. This pathway has been shown to be activated by mechanical procedures (e.g. pre and post conditioning) as well as by a number of pharmacological agents. Although the activation of this prosurvival signaling pathway induces the phosphorylation of a large number of substrates implicated in increased cell survival, when activated over a prolonged period this pathway can have detrimental consequences by facilitating unwanted growth and malignancies. Importantly PTEN (phosphatase and tensin homolog deleted on chromosome ten), is the main phosphatase which negatively regulates the PI3K/Akt pathway. In this review we discuss: a) the significance and the limitations of inhibiting PTEN in myocardial ischaemia/reperfusion injury; b) PTEN and its relationship to ischaemic preconditioning, c) the role of PTEN in the development of tolerance to chronic administration of drugs known to limit infarction by activating PI3K/Akt pathway when given acutely, and d) the possible role of PTEN in the ischaemic/reperfused diabetic heart. The experimental evidence discussed in this review illustrates the importance of PTEN inhibition in the protection of the heart against ischaemia/reperfusion injury. PMID:17293884

A Chimeric Protein PTEN-L-p53 Enters U251 Cells to Repress Proliferation and Invasion.

PubMed

Xiao, Man; An, Yang; Wang, Fengling; Yao, Chao; Zhang, Chu; Xin, Junfang; Duan, Yongjian; Zhao, Xiaofang; Fang, Na; Ji, Shaoping

2018-05-23

PTEN, a well-known tumor suppressor, dephosphorylates PIP3 and inhibits AKT activity. A translational variant of PTEN has been identified and termed PTEN-Long (PTEN-L). The additional 173 amino acids (PTEN-L leader) at the N-terminal constitute a potential signal peptide. Differing from canonical PTEN, PTEN-L is secreted into the extracellular fluid and re-enters recipient cells, playing the similar roles as PTEN in vivo and in vitro. This character confers the PTEN-L a therapeutic ability via directly protein delivering instead of traditional DNA and RNA vector options. In the present study, we employed PTEN-L leader to assemble a fusion protein, PTEN-L-p53, inosculated with the transcriptional regulator TP53, which is another powerful tumor suppressor. We overexpressed PTEN-L-p53 in HEK293T cells and detected it in both the cytoplasm and nucleus. Subsequently, we found that PTEN-L-p53 was secreted outside of the cells and detected in the culture media by immunoblotting. Furthermore, we demonstrated that PTEN-L-p53 freely entered the cells and suppressed the viability of U251cells (p53 R273H , a cell line with p53 R273H-mutation). PTEN-L-p53 is composed of endogenous protein/peptide bearing low immunogenicity, and only the junction region between PTEN-L leader and p53 can act as a new immune epitope. Accordingly, this fusion protein can potentially be used as a therapeutic option for TP53-abnormality cancers. Copyright © 2018. Published by Elsevier Inc.

Molecular Features of Phosphatase and Tensin Homolog (PTEN) Regulation by C-terminal Phosphorylation*

PubMed Central

Chen, Zan; Dempsey, Daniel R.; Thomas, Stefani N.; Hayward, Dawn; Bolduc, David M.; Cole, Philip A.

2016-01-01

PTEN is a tumor suppressor that functions to negatively regulate the PI3K/AKT pathway as the lipid phosphatase for phosphatidylinositol 3,4,5-triphosphate. Phosphorylation of a cluster of Ser/Thr residues (amino acids 380–385) on the C-terminal tail serves to alter the conformational state of PTEN from an open active state to a closed inhibited state, resulting in a reduction of plasma membrane localization and inhibition of enzyme activity. The relative contribution of each phosphorylation site to PTEN autoinhibition and the structural basis for the conformational closure is still unclear. To further the structural understanding of PTEN regulation by C-terminal tail phosphorylation, we used protein semisynthesis to insert stoichiometric and site-specific phospho-Ser/Thr(s) in the C-terminal tail of PTEN. Additionally, we employed photo-cross-linking to map the intramolecular PTEN interactions of the phospho-tail. Systematic evaluation of the PTEN C-tail phospho-cluster showed autoinhibition, and conformational closure was influenced by the aggregate effect of multiple phospho-sites rather than dominated by a single phosphorylation site. Moreover, photo-cross-linking suggested a direct interaction between the PTEN C-tail and a segment in the N-terminal region of the catalytic domain. Mutagenesis experiments provided additional insights into how the PTEN phospho-tail interacts with both the C2 and catalytic domains. PMID:27226612

Intermittent fasting uncovers and rescues cognitive phenotypes in PTEN neuronal haploinsufficient mice.

PubMed

Cabral-Costa, J V; Andreotti, D Z; Mello, N P; Scavone, C; Camandola, S; Kawamoto, E M

2018-06-05

Phosphatase and tensin homolog (PTEN) is an important protein with key modulatory functions in cell growth and survival. PTEN is crucial during embryogenesis and plays a key role in the central nervous system (CNS), where it directly modulates neuronal development and synaptic plasticity. Loss of PTEN signaling function is associated with cognitive deficits and synaptic plasticity impairment. Accordingly, Pten mutations have a strong link with autism spectrum disorder. In this study, neuronal Pten haploinsufficient male mice were subjected to a long-term environmental intervention - intermittent fasting (IF) - and then evaluated for alterations in exploratory, anxiety and learning and memory behaviors. Although no significant effects on spatial memory were observed, mutant mice showed impaired contextual fear memory in the passive avoidance test - an outcome that was effectively rescued by IF. In this study, we demonstrated that IF modulation, in addition to its rescue of the memory deficit, was also required to uncover behavioral phenotypes otherwise hidden in this neuronal Pten haploinsufficiency model.

One gene - many endocrine and metabolic syndromes: PTEN-opathies and precision medicine.

PubMed

Yehia, Lamis; Eng, Charis

2018-05-23

An average of 10% of all cancers (range 1-40%) are caused by heritable mutations and over the years, have become powerful models for precision medicine practice. Furthermore, such cancer predisposition genes for seemingly rare syndromes have turned out to help explain mechanisms of sporadic carcinogenesis and often inform normal development. The tumor suppressor PTEN encodes a ubiquitously expressed phosphatase that counteracts the PI3K/AKT/mTOR cascade - one of the most critical growth-promoting signaling pathways. Clinically, individuals with germline PTEN mutations have diverse phenotypes and fall under the umbrella term PTEN hamartoma tumor syndrome (PHTS). PHTS encompasses four clinically distinct allelic overgrowth syndromes, namely Cowden, Bannayan-Riley-Ruvalcaba, Proteus, and Proteus-like syndromes. Relatedly, mutations in other genes encoding components of the PI3K/AKT/mTOR pathway downstream of PTEN also predispose patients to partially overlapping clinical manifestations, with similar effects as PTEN malfunction. We refer to these syndromes as "PTEN-opathies." As a tumor suppressor and key regulator of normal development, PTEN dysfunction can cause a spectrum of phenotypes including benign overgrowths, malignancies, metabolic, and neurodevelopmental disorders. Relevant to clinical practice, the identification of PTEN mutations in patients not only establishes a PHTS molecular diagnosis, but also informs on more accurate cancer risk assessment and medical management of those patients and affected family members. Importantly, timely diagnosis is key, as early recognition allows for preventative measures such as high-risk screening and surveillance even prior to cancer onset. This review highlights the translational impact that the discovery of PTEN has had on the diagnosis, management, and treatment of PHTS.

Inhibition of PTEN and activation of Akt by menadione.

PubMed

Yoshikawa, Kyoko; Nigorikawa, Kiyomi; Tsukamoto, Mariko; Tamura, Namiko; Hazeki, Kaoru; Hazeki, Osamu

2007-04-01

Menadione (vitamin K(3)) has been shown to activate Erk in several cell lines. This effect has been shown to be due to the activation of EGF receptors (EGFR) as a result of inhibition of some protein tyrosine phosphatases. In the present study, we examined the effects of menadione on Akt in Chinese hamster ovary cells. The phosphorylation of Akt by menadione was not inhibited by AG1478, an inhibitor of EGFR. Menadione inhibited the lipid phosphatase activity of PTEN in a cell-free system. In an intact cell system, menadione inhibited the effect of transfected PTEN on Akt. Thus, one mechanism of its action was considered the accelerated activation of Akt through inhibition of PTEN. This was not the sole mechanism responsible for the EGFR-independent activation of Akt, because menadione attenuated the rate of Akt dephosphorylation even in PTEN-null PC3 cells. The decelerated inactivation of Akt, probably through inhibition of some tyrosine phosphatases, was considered another mechanism of its action.

Gastrin-releasing peptide-induced down-regulation of tumor suppressor protein PTEN (phosphatase and tensin homolog deleted on chromosome ten) in neuroblastomas.

PubMed

Qiao, Jingbo; Kang, Junghee; Cree, Jeremy; Evers, B Mark; Chung, Dai H

2005-05-01

To evaluate whether aggressive, undifferentiated neuroblastomas express tumor suppressor protein PTEN (phosphatase and tensin homolog deleted on chromosome ten) and to examine the effects of gastrin-releasing peptide (GRP) on PTEN gene and protein expression. We have previously shown that neuroblastomas secrete GRP, which binds to its cell surface receptor (GRP-R) to stimulate cell growth in an autocrine fashion. However, the effects of GRP on expression of the tumor suppressor gene PTEN have not been elucidated in neuroblastomas. Paraffin-embedded sections from human neuroblastomas were analyzed for PTEN and phospho-Akt protein expression by immunohistochemistry. Human neuroblastoma cell lines (SK-N-SH and SH-SY5Y) were stably transfected with the plasmid pEGFP-GRP-R to establish GRP-R overexpression cell lines, and the effects of GRP on PTEN gene and protein expression were determined. A decrease in the ratio of PTEN to phospho-Akt protein expression was identified in poorly differentiated neuroblastomas. An increase in GRP binding capacity was confirmed in GRP-R overexpressing cells, which demonstrated an accelerated constitutive cell growth rate. PTEN gene and protein expression was significantly decreased in GRP-R overexpressing cells when compared with controls. Our findings demonstrate decreased expression of the tumor suppressor protein PTEN in more aggressive undifferentiated neuroblastomas. An increase in GRP binding capacity, as a result of GRP-R overexpression, down-regulates PTEN expression. These findings suggest that an inhibition of the tumor suppressor gene PTEN may be an important regulatory mechanism involved in GRP-induced cell proliferation in neuroblastomas.

Deletion of Pten Expands Lung Epithelial Progenitor Pools and Confers Resistance to Airway Injury

PubMed Central

Tiozzo, Caterina; De Langhe, Stijn; Yu, Mingke; Londhe, Vedang A.; Carraro, Gianni; Li, Min; Li, Changgong; Xing, Yiming; Anderson, Stewart; Borok, Zea; Bellusci, Saverio; Minoo, Parviz

2009-01-01

Rationale: Pten is a tumor-suppressor gene involved in stem cell homeostasis and tumorigenesis. In mouse, Pten expression is ubiquitous and begins as early as 7 days of gestation. Pten−/− mouse embryos die early during gestation indicating a critical role for Pten in embryonic development. Objectives: To test the role of Pten in lung development and injury. Methods: We conditionally deleted Pten throughout the lung epithelium by crossing Ptenflox/flox with Nkx2.1-cre driver mice. The resulting PtenNkx2.1-cre mutants were analyzed for lung defects and response to injury. Measurements and Main Results: PtenNkx2.1-cre embryonic lungs showed airway epithelial hyperplasia with no branching abnormalities. In adult mice, PtenNkx2.1-cre lungs exhibit increased progenitor cell pools composed of basal cells in the trachea, CGRP/CC10 double-positive neuroendocrine cells in the bronchi, and CC10/SPC double-positive cells at the bronchioalveolar duct junctions. Pten deletion affected differentiation of various lung epithelial cell lineages, with a decreased number of terminally differentiated cells. Over time, PtenNxk2.1-cre epithelial cells residing in the bronchioalveolar duct junctions underwent proliferation and formed uniform masses, supporting the concept that the cells residing in this distal niche may also be the source of procarcinogenic stem cells. Finally, increased progenitor cells in all the lung compartments conferred an overall selective advantage to naphthalene injury compared with wild-type control mice. Conclusions: Pten has a pivotal role in lung stem cell homeostasis, cell differentiation, and consequently resistance to lung injury. PMID:19574443

Distinct functional outputs of PTEN signalling are controlled by dynamic association with β-arrestins

PubMed Central

Lima-Fernandes, Evelyne; Enslen, Hervé; Camand, Emeline; Kotelevets, Larissa; Boularan, Cédric; Achour, Lamia; Benmerah, Alexandre; Gibson, Lucien C D; Baillie, George S; Pitcher, Julie A; Chastre, Eric; Etienne-Manneville, Sandrine; Marullo, Stefano; Scott, Mark G H

2011-01-01

The tumour suppressor PTEN (phosphatase and tensin deleted on chromosome 10) regulates major cellular functions via lipid phosphatase-dependent and -independent mechanisms. Despite its fundamental pathophysiological importance, how PTEN's cellular activity is regulated has only been partially elucidated. We report that the scaffolding proteins β-arrestins (β-arrs) are important regulators of PTEN. Downstream of receptor-activated RhoA/ROCK signalling, β-arrs activate the lipid phosphatase activity of PTEN to negatively regulate Akt and cell proliferation. In contrast, following wound-induced RhoA activation, β-arrs inhibit the lipid phosphatase-independent anti-migratory effects of PTEN. β-arrs can thus differentially control distinct functional outputs of PTEN important for cell proliferation and migration. PMID:21642958

RAS/ERK modulates TGFbeta-regulated PTEN expression in human pancreatic adenocarcinoma cells.

PubMed

Chow, Jimmy Y C; Quach, Khai T; Cabrera, Betty L; Cabral, Jennifer A; Beck, Stayce E; Carethers, John M

2007-11-01

Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is rarely mutated in pancreatic cancers, but its regulation by transforming growth factor (TGF)-beta might mediate growth suppression and other oncogenic actions. Here, we examined the role of TGFbeta and the effects of oncogenic K-RAS/ERK upon PTEN expression in the absence of SMAD4. We utilized two SMAD4-null pancreatic cell lines, CAPAN-1 (K-RAS mutant) and BxPc-3 (WT-K-RAS), both of which express TGFbeta surface receptors. Cells were treated with TGFbeta1 and separated into cytosolic/nuclear fractions for western blotting with phospho-SMAD2, SMAD 2, 4 phospho-ATP-dependent tyrosine kinases (Akt), Akt and PTEN antibodies. PTEN mRNA levels were assessed by reverse transcriptase-polymerase chain reaction. The MEK1 inhibitor, PD98059, was used to block the downstream action of oncogenic K-RAS/ERK, as was a dominant-negative (DN) K-RAS construct. TGFbeta increased phospho-SMAD2 in both cytosolic and nuclear fractions. PD98059 treatment further increased phospho-SMAD2 in the nucleus of both pancreatic cell lines, and DN-K-RAS further improved SMAD translocation in K-RAS mutant CAPAN cells. TGFbeta treatment significantly suppressed PTEN protein levels concomitant with activation of Akt by 48 h through transcriptional reduction of PTEN mRNA that was evident by 6 h. TGFbeta-induced PTEN suppression was reversed by PD98059 and DN-K-RAS compared with treatments without TGFbeta. TGFbeta-induced PTEN expression was inversely related to cellular proliferation. Thus, oncogenic K-RAS/ERK in pancreatic adenocarcinoma facilitates TGFbeta-induced transcriptional down-regulation of the tumor suppressor PTEN in a SMAD4-independent manner and could constitute a signaling switch mechanism from growth suppression to growth promotion in pancreatic cancers.

A pseudogene long noncoding RNA network regulates PTEN transcription and translation in human cells

PubMed Central

Johnsson, Per; Ackley, Amanda; Vidarsdottir, Linda; Lui, Weng-Onn; Corcoran, Martin; Grandér, Dan; Morris, Kevin V.

2013-01-01

PTEN is a tumor suppressor gene that has been shown to be under the regulatory control of a PTEN pseudogene expressed noncoding RNA, PTENpg1. Here, we characterize a previously unidentified PTENpg1 encoded antisense RNA (asRNA), which regulates PTEN transcription and PTEN mRNA stability. We find two PTENpg1 asRNA isoforms, alpha and beta. The alpha isoform functions in trans, localizes to the PTEN promoter, and epigenetically modulates PTEN transcription by the recruitment of DNMT3a and EZH2. In contrast, the beta isoform interacts with PTENpg1 through an RNA:RNA pairing interaction, which affects PTEN protein output via changes of PTENpg1 stability and microRNA sponge activity. Disruption of this asRNA-regulated network induces cell cycle arrest and sensitizes cells to doxorubicin, suggesting a biological function for the respective PTENpg1 expressed asRNAs. PMID:23435381

A pseudogene long-noncoding-RNA network regulates PTEN transcription and translation in human cells.

PubMed

Johnsson, Per; Ackley, Amanda; Vidarsdottir, Linda; Lui, Weng-Onn; Corcoran, Martin; Grandér, Dan; Morris, Kevin V

2013-04-01

PTEN is a tumor-suppressor gene that has been shown to be under the regulatory control of a PTEN pseudogene expressed noncoding RNA, PTENpg1. Here, we characterize a previously unidentified PTENpg1-encoded antisense RNA (asRNA), which regulates PTEN transcription and PTEN mRNA stability. We find two PTENpg1 asRNA isoforms, α and β. The α isoform functions in trans, localizes to the PTEN promoter and epigenetically modulates PTEN transcription by the recruitment of DNA methyltransferase 3a and Enhancer of Zeste. In contrast, the β isoform interacts with PTENpg1 through an RNA-RNA pairing interaction, which affects PTEN protein output through changes of PTENpg1 stability and microRNA sponge activity. Disruption of this asRNA-regulated network induces cell-cycle arrest and sensitizes cells to doxorubicin, which suggests a biological function for the respective PTENpg1 expressed asRNAs.

Nuclear PTEN deficiency causes microcephaly with decreased neuronal soma size and increased seizure susceptibility.

PubMed

Igarashi, Atsushi; Itoh, Kie; Yamada, Tatsuya; Adachi, Yoshihiro; Kato, Takashi; Murata, Daisuke; Sesaki, Hiromi; Iijima, Miho

2018-06-15

Defects in phosphatase and tensin homolog (PTEN) are associated with neurological disorders and tumors. PTEN functions at two primary intracellular locations: the plasma membrane and the nucleus. At the membrane, PTEN functions as a phosphatidylinositol (3,4,5)-trisphosphate phosphatase and suppresses PI 3-kinase signaling that drives cell growth and tumorigenesis. However, the in vivo function of nuclear PTEN is unclear. Here, using CRISPR/Cas9, we generated a mouse model in which PTEN levels in the nucleus are decreased. Nuclear PTEN-deficient mice were born with microcephaly and maintained a small brain during adulthood. The size of neuronal soma was significantly smaller in the cerebellum, cerebral cortex, and hippocampus. Also, these mice were prone to seizure. No changes in PI 3-kinase signaling were observed. By contrast, the size of other organs was unaffected. Therefore, nuclear PTEN is essential for the health of the brain by promoting the growth of neuronal soma size during development. © 2018 Igarashi et al.

Loss of PTEN expression is associated with colorectal cancer liver metastasis and poor patient survival

PubMed Central

Sawai, Hirozumi; Yasuda, Akira; Ochi, Nobuo; Ma, Jiachi; Matsuo, Yoichi; Wakasugi, Takehiro; Takahashi, Hiroki; Funahashi, Hitoshi; Sato, Mikinori; Takeyama, Hiromitsu

2008-01-01

Background The tumour suppressor phosphatase and tensin homolog (PTEN) is an important negative regulator of cell-survival signaling. To evaluate the correlation between PTEN expression and clinicopathological characteristics of colorectal cancer patients with and without liver metastases, we investigated PTEN expression in primary colorectal cancer and colorectal cancer liver metastases. Methods Sixty-nine pairs of primary colorectal cancer and corresponding liver metastasis specimens were analyzed immunohistochemically, and the correlation between immunohistochemical findings and clinicopathological factors was investigated. Seventy primary colorectal cancer specimens from patients without liver metastases were used as controls. Results PTEN was strongly expressed in 44 (62.9%) colorectal cancer specimens from patients without liver metastases. In contrast, PTEN was weakly expressed in 52 (75.4%) primary colorectal cancer specimens from patients with liver metastases, and was absent in liver metastases. Weak PTEN expression in colorectal cancer tissues was significantly associated with advanced TNM stage (p < 0.01) and lymph node metastasis (p < 0.05). PTEN expression was significantly stronger in primary colorectal cancer specimens from patients without liver metastases. Furthermore, among colorectal cancer patients with liver metastases, the 5-year survival rate was significantly higher in patients with positive PTEN expression compared to those with negative PTEN expression (p = 0.012). Conclusion Our results suggest that loss of PTEN expression is involved with colorectal cancer aggressive capacity and that diagnostic evaluation of PTEN expression may provide valuable prognostic information to aid treatment strategies for colorectal cancer patients. PMID:19036165

Unique roles of estrogen-dependent Pten control in epithelial cell homeostasis of mouse vagina.

PubMed

Miyagawa, S; Sato, M; Sudo, T; Yamada, G; Iguchi, T

2015-02-19

Numerous studies support a role of phosphatase and tensin homolog deleted from chromosome 10 (Pten) as a tumor suppressor gene that controls epithelial cell homeostasis to prevent tumor formation. Mouse vaginal epithelium cyclically exhibits cell proliferation and differentiation in response to estrogen and provides a unique model for analyzing homeostasis of stratified squamous epithelia. We analyzed vaginal epithelium-specific Pten conditional knockout (CKO) mice to provide new insights into Pten/phosphoinositide-3-kinase (PI3K)/Akt function. The vaginal epithelium of ovariectomized (OVX) mice (control) was composed of 1-2 layers of cuboidal cells, whereas OVX CKO mice exhibited epithelial hyperplasia in the suprabasal cells with increased cell mass and mucin production. This is possibly due to misactivation of mammalian target of rapamycin and mitogen-activated protein kinase. Intriguingly, estrogen administration to OVX Pten CKO mice induced stratification and keratinized differentiation in the vaginal epithelium, as in estrogen-treated controls. We found that Pten is exclusively expressed in the suprabasal cells in the absence of estrogens, whereas estrogen administration induced Pten expression in the basal cells. This suggests that Pten acts to prevent excessive cell proliferation as in the case of other squamous tissues. Thus, Pten exhibits a dual role on the control of vaginal homeostasis, depending on whether estrogens are present or absent. Our results provide new insights into how Pten functions in tissue homeostasis.

Cytoplasm-predominant Pten associates with increased region-specific brain tyrosine hydroxylase and dopamine D2 receptors in mouse model with autistic traits.

PubMed

He, Xin; Thacker, Stetson; Romigh, Todd; Yu, Qi; Frazier, Thomas W; Eng, Charis

2015-01-01

Autism spectrum disorder (ASD) is a group of neurodevelopmental disorders characterized by impairment in social communication/interaction and inflexible/repetitive behavior. Several lines of evidence support genetic factors as a predominant cause of ASD. Among those autism susceptibility genes that have been identified, the PTEN tumor suppressor gene, initially identified as predisposing to Cowden heritable cancer syndrome, was found to be mutated in a subset of ASD patients with extreme macrocephaly. However, the ASD-relevant molecular mechanism mediating the effect of PTEN mutations remains elusive. We developed a Pten knock-in murine model to study the effects of Pten germline mutations, specifically altering subcellular localization, in ASD. Proteins were isolated from the hemispheres of the male littermates, and Western blots were performed to determine protein expression levels of tyrosine hydroxylase (TH). Immunohistochemical stains were carried out to validate the localization of TH and dopamine D2 receptors (D2R). PC12 cells ectopically expressing either wild-type or missense mutant PTEN were then compared for the differences in TH expression. Mice carrying Pten mutations have high TH and D2R in the striatum and prefrontal cortex. They also have increased phosphorylation of cAMP response element-binding protein (CREB) and TH. Mechanistically, PTEN downregulates TH production in PC12 cells via inhibiting the phosphoinositide 3-kinase (PI3K)/CREB signaling pathway, while PTEN reduces TH phosphorylation via suppressing MAPK pathway. Unlike wild-type PTEN but similar to the mouse knock-in mutant Pten, three naturally occurring missense mutations of PTEN that we previously identified in ASD patients, H93R, F241S, and D252G, were not able to suppress TH when overexpressed in PC12 cells. In addition, two other PTEN missense mutations, C124S (pan phosphatase dead) and G129E (lipid phosphatase dead), failed to suppress TH when ectopically expressed in PC12 cells

Promoter Methylation of PTEN Is a Significant Prognostic Factor in Melanoma Survival.

PubMed

Roh, Mi Ryung; Gupta, Sameer; Park, Kyu-Hyun; Chung, Kee Yang; Lauss, Martin; Flaherty, Keith T; Jönsson, Göran; Rha, Sun Young; Tsao, Hensin

2016-05-01

Structural compromise of the tumor suppressor gene, phosphatase and tensin homolog (PTEN), occurs in 10% of melanoma specimens, and loss of PTEN expression through DNA methylation of the PTEN promoter region has also been reported in a number of other malignancies. However, the role of PTEN promoter methylation in melanoma is not well understood. We thus sought to elucidate the prevalence of PTEN promoter methylation in melanoma specimens, its relationship to clinical features, and its impact on the outcome of patients with melanoma. PTEN promoter methylation data were acquired from an archived primary Korean melanoma cohort (KMC) of 158 patients and, for validation, 234 patients from The Cancer Genome Atlas melanoma (TCGA-MEL) cohort. Hierarchical clustering was performed to identify PTEN "high methylated" and "low methylated" samples. Subsequently, differences in clinical features and outcomes based on PTEN promoter methylation status were then analyzed using SPSS and R. In the KMC, all tumors were acquired from primary tumors and 65.7% (n = 105) were acral or mucosal by site, whereas in the TCGA-MEL cohort, 90.5% of the tumors were from regional lymph node and distant metastatic lesions. Overall, 17.7% and 45.7% of the specimens harbored BRAF mutations in the KMC and TCGA-MEL cohort, respectively. Neuroblastoma RAS viral oncogene homolog was mutated in 12.2% and 26.9% of the tumors in the KMC and TCGA-MEL cohort, respectively. In the KMC, 31 cases (19.6%) were included in the high methylated group versus 142 cases (60.7%) in the TCGA-MEL cohort (P < 0.001). Multivariate Cox-regression analysis revealed promoter methylation of PTEN to be an independent negative prognostic factor for survival in both the KMC (hazard ratio 3.76, 95% confidence interval = 1.24-11.12, P = 0.017) and TCGA-MEL cohort (HR 1.88, 95% confidence interval = 1.13-3.12, P = 0.015). Our results indicate that PTEN promoter methylation is an independent predictor for impaired survival in

PTEN Loss Increases PD-L1 Protein Expression and Affects the Correlation between PD-L1 Expression and Clinical Parameters in Colorectal Cancer

PubMed Central

Lu, Biyan; Wang, Chenliang; Zhang, Junxiao; Huang, Lanlan; Wang, Xiaoyan; Timmons, Christine L.; Hu, Jun; Liu, Bindong; Wu, Xiaojian; Wang, Lei; Wang, Jianping; Liu, Huanliang

2013-01-01

Background Programmed death ligand-1 (PD-L1) has been identified as a factor associated with poor prognosis in a range of cancers, and was reported to be mainly induced by PTEN loss in gliomas. However, the clinical effect of PD-L1 and its regulation by PTEN has not yet been determined in colorectal cancer (CRC). In the present study, we verified the regulation of PTEN on PD-L1 and further determined the effect of PTEN on the correlation between PD-L1 expression and clinical parameters in CRC. Methods/Results RNA interference approach was used to down-regulate PTEN expression in SW480, SW620 and HCT116 cells. It was showed that PD-L1 protein, but not mRNA, was significantly increased in cells transfected with siRNA PTEN compared with the negative control. Moreover, the capacity of PTEN to regulate PD-L1 expression was not obviously affected by IFN-γ, the main inducer of PD-L1. Tissue microarray immunohistochemistry was used to detect PD-L1 and PTEN in 404 CRC patient samples. Overexpression of PD-L1 was significantly correlated with distant metastasis (P<0.001), TNM stage (P<0.01), metastatic progression (P<0.01) and PTEN expression (P<0.001). Univariate analysis revealed that patients with high PD-L1 expression had a poor overall survival (P<0.001). However, multivariate analysis did not support PD-L1 as an independent prognostic factor (P = 0.548). Univariate (P<0.001) and multivariate survival (P<0.001) analysis of 310 located CRC patients revealed that high level of PD-L1 expression was associated with increased risks of metastatic progression. Furthermore, the clinical effect of PD-L1 on CRC was not statistically significant in a subset of 39 patients with no PTEN expression (distant metastasis: P = 0.102; TNM stage: P = 0.634, overall survival: P = 0.482). Conclusions PD-L1 can be used to identify CRC patients with high risk of metastasis and poor prognosis. This clinical manifestation may be partly associated with PTEN expression. PMID

PTEN loss increases PD-L1 protein expression and affects the correlation between PD-L1 expression and clinical parameters in colorectal cancer.

PubMed

Song, Minmin; Chen, Defeng; Lu, Biyan; Wang, Chenliang; Zhang, Junxiao; Huang, Lanlan; Wang, Xiaoyan; Timmons, Christine L; Hu, Jun; Liu, Bindong; Wu, Xiaojian; Wang, Lei; Wang, Jianping; Liu, Huanliang

2013-01-01

Programmed death ligand-1 (PD-L1) has been identified as a factor associated with poor prognosis in a range of cancers, and was reported to be mainly induced by PTEN loss in gliomas. However, the clinical effect of PD-L1 and its regulation by PTEN has not yet been determined in colorectal cancer (CRC). In the present study, we verified the regulation of PTEN on PD-L1 and further determined the effect of PTEN on the correlation between PD-L1 expression and clinical parameters in CRC. RNA interference approach was used to down-regulate PTEN expression in SW480, SW620 and HCT116 cells. It was showed that PD-L1 protein, but not mRNA, was significantly increased in cells transfected with siRNA PTEN compared with the negative control. Moreover, the capacity of PTEN to regulate PD-L1 expression was not obviously affected by IFN-γ, the main inducer of PD-L1. Tissue microarray immunohistochemistry was used to detect PD-L1 and PTEN in 404 CRC patient samples. Overexpression of PD-L1 was significantly correlated with distant metastasis (P<0.001), TNM stage (P<0.01), metastatic progression (P<0.01) and PTEN expression (P<0.001). Univariate analysis revealed that patients with high PD-L1 expression had a poor overall survival (P<0.001). However, multivariate analysis did not support PD-L1 as an independent prognostic factor (P = 0.548). Univariate (P<0.001) and multivariate survival (P<0.001) analysis of 310 located CRC patients revealed that high level of PD-L1 expression was associated with increased risks of metastatic progression. Furthermore, the clinical effect of PD-L1 on CRC was not statistically significant in a subset of 39 patients with no PTEN expression (distant metastasis: P = 0.102; TNM stage: P = 0.634, overall survival: P = 0.482). PD-L1 can be used to identify CRC patients with high risk of metastasis and poor prognosis. This clinical manifestation may be partly associated with PTEN expression.

Germline disruption of Pten localization causes enhanced sex-dependent social motivation and increased glial production.

PubMed

Tilot, Amanda K; Gaugler, Mary K; Yu, Qi; Romigh, Todd; Yu, Wanfeng; Miller, Robert H; Frazier, Thomas W; Eng, Charis

2014-06-15

PTEN Hamartoma Tumor Syndrome (PHTS) is an autosomal-dominant genetic condition underlying a subset of autism spectrum disorder (ASD) with macrocephaly. Caused by germline mutations in PTEN, PHTS also causes increased risks of multiple cancers via dysregulation of the PI3K and MAPK signaling pathways. Conditional knockout models have shown that neural Pten regulates social behavior, proliferation and cell size. Although much is known about how the intracellular localization of PTEN regulates signaling in cancer cell lines, we know little of how PTEN localization influences normal brain physiology and behavior. To address this, we generated a germline knock-in mouse model of cytoplasm-predominant Pten and characterized its behavioral and cellular phenotypes. The homozygous Pten(m3m4) mice have decreased total Pten levels including a specific drop in nuclear Pten and exhibit region-specific increases in brain weight. The Pten(m3m4) model displays sex-specific increases in social motivation, poor balance and normal recognition memory-a profile reminiscent of some individuals with high functioning ASD. The cytoplasm-predominant protein caused cellular hypertrophy limited to the soma and led to increased NG2 cell proliferation and accumulation of glia. The animals also exhibit significant astrogliosis and microglial activation, indicating a neuroinflammatory phenotype. At the signaling level, Pten(m3m4) mice show brain region-specific differences in Akt activation. These results demonstrate that differing alterations to the same autism-linked gene can cause distinct behavioral profiles. The Pten(m3m4) model is the first murine model of inappropriately elevated social motivation in the context of normal cognition and may expand the range of autism-related behaviors replicated in animal models. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

PTEN induces apoptosis and cavitation via HIF-2-dependent Bnip3 upregulation during epithelial lumen formation.

PubMed

Qi, Y; Liu, J; Saadat, S; Tian, X; Han, Y; Fong, G-H; Pandolfi, P P; Lee, L Y; Li, S

2015-05-01

The tumor suppressor phosphatase and tensin homolog (PTEN) dephosphorylates PIP3 and antagonizes the prosurvival PI3K-Akt pathway. Targeted deletion of PTEN in mice led to early embryonic lethality. To elucidate its role in embryonic epithelial morphogenesis and the underlying mechanisms, we used embryonic stem cell-derived embryoid body (EB), an epithelial cyst structurally similar to the periimplantation embryo. PTEN is upregulated during EB morphogenesis in parallel with apoptosis of core cells, which mediates EB cavitation. Genetic ablation of PTEN causes Akt overactivation, apoptosis resistance and cavitation blockade. However, rescue experiments using mutant PTEN and pharmacological inhibition of Akt suggest that the phosphatase activity of PTEN and Akt are not involved in apoptosis-mediated cavitation. Instead, hypoxia-induced upregulation of Bnip3, a proapoptotic BH3-only protein, mediates PTEN-dependent apoptosis and cavitation. PTEN inactivation inhibits hypoxia- and reactive oxygen species-induced Bnip3 elevation. Overexpression of Bnip3 in PTEN-null EBs rescues apoptosis of the core cells. Mechanistically, suppression of Bnip3 following PTEN loss is likely due to reduction of hypoxia-inducible factor-2α (HIF-2α) because forced expression of an oxygen-stable HIF-2α mutant rescues Bnip3 expression and apoptosis. Lastly, we show that HIF-2α is upregulated by PTEN at both transcriptional and posttranscriptional levels. Ablation of prolyl hydroxylase domain-containing protein 2 (PHD2) in normal EBs or inhibition of PHD activities in PTEN-null EBs stabilizes HIF-2α and induces Bnip3 and caspase-3 activation. Altogether, these results suggest that PTEN is required for apoptosis-mediated cavitation during epithelial morphogenesis by regulating the expression of HIF-2α and Bnip3.

Development and characterization of NEX- Pten, a novel forebrain excitatory neuron-specific knockout mouse.

PubMed

Kazdoba, Tatiana M; Sunnen, C Nicole; Crowell, Beth; Lee, Gum Hwa; Anderson, Anne E; D'Arcangelo, Gabriella

2012-01-01

The phosphatase and tensin homolog located on chromosome 10 (PTEN) suppresses the activity of the phosphoinositide-3-kinase/Akt/mammalian target of rapamycin (mTOR) pathway, a signaling cascade critically involved in the regulation of cell proliferation and growth. Human patients carrying germ line PTEN mutations have an increased predisposition to tumors, and also display a variety of neurological symptoms and increased risk of epilepsy and autism, implicating PTEN in neuronal development and function. Consistently, loss of Pten in mouse neural cells results in ataxia, seizures, cognitive abnormalities, increased soma size and synaptic abnormalities. To better understand how Pten regulates the excitability of principal forebrain neurons, a factor that is likely to be altered in cognitive disorders, epilepsy and autism, we generated a novel conditional knockout mouse line (NEX-Pten) in which Cre, under the control of the NEX promoter, drives the deletion of Pten specifically in early postmitotic, excitatory neurons of the developing forebrain. Homozygous mutant mice exhibited a massive enlargement of the forebrain, and died shortly after birth due to excessive mTOR activation. Analysis of the neonatal cerebral cortex further identified molecular defects resulting from Pten deletion that likely affect several aspects of neuronal development and excitability. Copyright © 2012 S. Karger AG, Basel.

Understanding the stereospecific interactions of 3-deoxyphosphatidylinositol derivatives with the PTEN phosphatase domain

PubMed Central

Wang, Qin; Wei, Yang; Mottamal, Madhusoodanan; Roberts, Mary F.; Krilov, Goran

2011-01-01

PTEN is an important control element of PI3K/AKT signaling involved in controlling the processes of embryonic development, cell migration and apoptosis. While its dysfunction is implicated in a large fraction of cancers, PTEN activity in the same pathway may also contribute to metabolic syndromes such as diabetes. In those cases, selective inhibitors of PTEN may be useful. A new class of chiral PTEN inhibitors based on the 3-deoxy-phosphatidylinositol derivatives was recently identified [Wang et al. (2008) J. Am. Chem. Soc. 130, 7746]. However, lack of detailed understanding of protein-ligand interactions has hampered efforts to develop effective agonists or antagonists of PTEN. Here, we use computational modeling to characterize the interactions of the diverse 3-deoxyphosphatidylinositol inhibitors with the PTEN protein. We show that, while each of the compounds binds with the inositol headgroup inserting into the proposed active site of the PTEN phosphatase domain, hydrogen bonding restrictions lead to distinct binding geometries for ligand pairs of opposite chirality. We furthermore demonstrate that the binding modes differ primarily in the orientation of acyl tails of the ligands and that the activity of the compounds is primarily controlled by the effectiveness of tail-protein contacts. These findings are confirmed by binding affinity calculations which are in good agreement with experiment. Finally, we show that while more potent D-series ligands bind in a manner similar to that of the native substrate, an alternate hydrophobic pocket suitable for binding the opposite chirality L-series inhibitors exists, offering the possibility of designing highly selective PTEN- targeting compounds. PMID:20538496

The expression of PTEN in the development of mouse cochlear lateral wall.

PubMed

Dong, Y; Sui, L; Yamaguchi, F; Kamitori, K; Hirata, Y; Hossain, A; Noguchi, C; Katagi, A; Nishio, M; Suzuki, A; Lou, X; Tokuda, M

2014-01-31

Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is a tumor suppressor gene that regulates various cell processes including proliferation, growth, synaptogenesis, neural and glioma stem/progenitor cell renewal. In addition, PTEN can regulate sensory cell proliferation and differentiation of hair bundles in the mammalian cochlea. In this study we use immunofluorescence, Western blot and reverse transcriptase-polymerase chain reaction (RT-PCR) to reveal the expression of PTEN in the developing cochlear lateral wall, which is crucial for regulating K(+) homeostasis. Relatively high levels of PTEN are initially expressed in the marginal cells (MCs) of the lateral wall at embryonic day (E) 17.5 when they start to differentiate. Similarly high levels are subsequently expressed in differentiating root cells (RCs) at postnatal day (P) 3 and then in spiral ligament fibrocytes (SLFs) at P 10. In the mature cochlea, PTEN expression is low or undetectable in MCs and SLFs but it remains high in RCs and their processes. The expression pattern for PTEN in the developing lateral wall suggests that it plays a critical role in the differentiation of the cellular pathways that regulate K(+) homeostasis in the cochlea. Copyright © 2013 IBRO. Published by Elsevier Ltd. All rights reserved.

Region-specific role for Pten in maintenance of epithelial phenotype and integrity

PubMed Central

Flodby, Per; Sunohara, Mitsuhiro; Castillo, Dan R.; McConnell, Alicia M.; Krishnaveni, Manda S.; Banfalvi, Agnes; Li, Min; Stripp, Barry; Zhou, Beiyun; Crandall, Edward D.; Minoo, Parviz

2017-01-01

Previous studies have demonstrated resistance to naphthalene-induced injury in proximal airways of mice with lung epithelial-specific deletion of the tumor-suppressor gene Pten, attributed to increased proliferation of airway progenitors. We tested effects of Pten loss following bleomycin injury, a model typically used to study distal lung epithelial injury, in conditional PtenSFTPC-cre knockout mice. Pten-deficient airway epithelium exhibited marked hyperplasia, particularly in small bronchioles and at bronchoalveolar duct junctions, with reduced E-cadherin and β-catenin expression between cells toward the luminal aspect of the hyperplastic epithelium. Bronchiolar epithelial and alveolar epithelial type II (AT2) cells in PtenSFTPC-cre mice showed decreased expression of epithelial markers and increased expression of mesenchymal markers, suggesting at least partial epithelial-mesenchymal transition at baseline. Surprisingly, and in contrast to previous studies, mutant mice were exquisitely sensitive to bleomycin, manifesting rapid weight loss, respiratory distress, increased early mortality (by day 5), and reduced dynamic lung compliance. This was accompanied by sloughing of the hyperplastic airway epithelium with occlusion of small bronchioles by cellular debris, without evidence of increased parenchymal lung injury. Increased airway epithelial cell apoptosis due to loss of antioxidant defenses, reflected by decreased expression of superoxide dismutase 3, in combination with deficient intercellular adhesion, likely predisposed to airway sloughing in knockout mice. These findings demonstrate an important role for Pten in maintenance of airway epithelial phenotype integrity and indicate that responses to Pten deletion in respiratory epithelium following acute lung injury are highly context-dependent and region-specific. PMID:27864284

The significance of PTEN and AKT aberrations in pediatric T-cell acute lymphoblastic leukemia

PubMed Central

Zuurbier, Linda; Petricoin, Emanuel F.; Vuerhard, Maartje J.; Calvert, Valerie; Kooi, Clarissa; Buijs-Gladdines, Jessica G.C.A.M.; Smits, Willem K.; Sonneveld, Edwin; Veerman, Anjo J.P.; Kamps, Willem A.; Horstmann, Martin; Pieters, Rob; Meijerink, Jules P.P.

2012-01-01

Background PI3K/AKT pathway mutations are found in T-cell acute lymphoblastic leukemia, but their overall impact and associations with other genetic aberrations is unknown. PTEN mutations have been proposed as secondary mutations that follow NOTCH1-activating mutations and cause cellular resistance to γ-secretase inhibitors. Design and Methods The impact of PTEN, PI3K and AKT aberrations was studied in a genetically well-characterized pediatric T-cell leukemia patient cohort (n=146) treated on DCOG or COALL protocols. Results PTEN and AKT E17K aberrations were detected in 13% and 2% of patients, respectively. Defective PTEN-splicing was identified in incidental cases. Patients without PTEN protein but lacking exon-, splice-, promoter mutations or promoter hypermethylation were present. PTEN/AKT mutations were especially abundant in TAL- or LMO-rearranged leukemia but nearly absent in TLX3-rearranged patients (P=0.03), the opposite to that observed for NOTCH1-activating mutations. Most PTEN/AKT mutant patients either lacked NOTCH1-activating mutations (P=0.006) or had weak NOTCH1-activating mutations (P=0.011), and consequently expressed low intracellular NOTCH1, cMYC and MUSASHI levels. T-cell leukemia patients without PTEN/AKT and NOTCH1-activating mutations fared well, with a cumulative incidence of relapse of only 8% versus 35% for PTEN/AKT and/or NOTCH1-activated patients (P=0.005). Conclusions PI3K/AKT pathway aberrations are present in 18% of pediatric T-cell acute lymphoblastic leukemia patients. Absence of strong NOTCH1-activating mutations in these cases may explain cellular insensitivity to γ-secretase inhibitors. PMID:22491738

Loss of CDH1 and Pten accelerates cellular invasiveness and angiogenesis in the mouse uterus.

PubMed

Lindberg, Mallory E; Stodden, Genna R; King, Mandy L; MacLean, James A; Mann, Jordan L; DeMayo, Francesco J; Lydon, John P; Hayashi, Kanako

2013-07-01

E-cadherin (CDH1) is a cell adhesion molecule that coordinates key morphogenetic processes regulating cell growth, cell proliferation, and apoptosis. Loss of CDH1 is a trademark of the cellular event epithelial to mesenchymal transition, which increases the metastatic potential of malignant cells. PTEN is a tumor-suppressor gene commonly mutated in many human cancers, including endometrial cancer. In the mouse uterus, ablation of Pten induces epithelial hyperplasia, leading to endometrial carcinomas. However, loss of Pten alone does not affect longevity until around 5 mo. Similarly, conditional ablation of Cdh1 alone does not predispose mice to cancer. In this study, we characterized the impact of dual Cdh1 and Pten ablation (Cdh1(d/d) Pten(d/d)) in the mouse uterus. We observed that Cdh1(d/d) Pten(d/d) mice died at Postnatal Days 15-19 with massive blood loss. Their uteri were abnormally structured with curly horns, disorganized epithelial structure, and increased cell proliferation. Co-immunostaining of KRT8 and ACTA2 showed invasion of epithelial cells into the myometrium. Further, the uteri of Cdh1(d/d) Pten(d/d) mice had prevalent vascularization in both the endometrium and myometrium. We also observed reduced expression of estrogen and progesterone receptors, loss of cell adherens, and tight junction molecules (CTNNB1 and claudin), as well as activation of AKT in the uteri of Cdh1(d/d) Pten(d/d) mice. However, complex hyperplasia was not found in the uteri of Cdh1(d/d) Pten(d/d) mice. Collectively, these findings suggest that ablation of Pten with Cdh1 in the uterus accelerates cellular invasiveness and angiogenesis and causes early death.

Short term feeding of a high fat diet exerts an additive effect on hepatocellular damage and steatosis in liver-specific PTEN knockout mice

USDA-ARS?s Scientific Manuscript database

Hepatospecific deletion of PTEN results in constitutive activation of Akt and increased lipogenesis. In mice, the addition of a high fat diet (HFD) downregulates lipogenesis. The aim of this study was to determine the effects of a HFD on hepatocellular damage induced by deletion of PTEN. Twelve-week...

Exclusion of a major role for the PTEN tumour-suppressor gene in breast carcinomas

PubMed Central

Freihoff, D; Kempe, A; Beste, B; Wappenschmidt, B; Kreyer, E; Hayashi, Y; Meindl, A; Krebs, D; Wiestler, O D; Deimling, A von; Schmutzler, R K

1999-01-01

PTEN is a novel tumour-suppressor gene located on chromosomal band 10q23.3. This region displays frequent loss of heterozygosity (LOH) in a variety of human neoplasms including breast carcinomas. The detection of PTEN mutations in Cowden disease and in breast carcinoma cell lines suggests that PTEN may be involved in mammary carcinogenesis. We here report a mutational analysis of tumour specimens from 103 primary breast carcinomas and constitutive DNA from 25 breast cancer families. The entire coding region of PTEN was screened by single-strand conformation polymorphism (SSCP) analysis and direct sequencing using intron-based primers. No germline mutations could be identified in the breast cancer families and only one sporadic carcinoma carried a PTEN mutation at one allele. In addition, all sporadic tumours were analysed for homozygous deletions by differential polymerase chain reaction (PCR) and for allelic loss using the microsatellite markers D10S215, D10S564 and D10S573. No homozygous deletions were detected and only 10 out of 94 informative tumours showed allelic loss in the PTEN region. These results suggest that PTEN does not play a major role in breast cancer formation. 1999 Cancer Research Campaign PMID:10070865

The PTEN/Akt Signaling Pathway Mediates Myocardial Apoptosis in Swine After Coronary Microembolization.

PubMed

Wang, Jiangyou; Chen, Han; Su, Qiang; Zhou, You; Liu, Tao; Li, Lang

2016-09-01

Phosphatase and the tensin homolog deleted on chromosome ten (PTEN) has been recognized as a promoter of apoptosis in various tissues and has been shown to be upregulated in circumstances of coronary microembolization (CME). We hypothesized that the upregulation of PTEN correlates with CME-induced myocardial apoptosis. Swine CME was induced by an intracoronary injection of inert plastic microspheres (diameter of 42 μm) into the left anterior descending coronary, with or without pretreatment of the PTEN small-interfering RNA (siRNA). Echocardiological measurements, a pathological examination, Terminal-deoxynucleoitidyl Transferase Mediated Nick End Labeling (TUNEL) staining, and Western blotting, were performed to assess their functional, morphological, and molecular effects in CME. PTEN was aberrantly upregulated in cardiomyocytes following CME. Downregulation of PTEN in vivo via siRNA was associated with improved cardiac function and attenuated myocardial apoptosis; concomitantly inhibited the expression of key proapoptotic proteins, such as phosphorylated Bad (p-Bad); cleaved caspase-3; and enhanced the expression of key antiapoptotic proteins, such as phosphorylated protein kinase B (p-Akt). However, there was no difference in the Akt-regulated downstream protein IκB kinases (IKKα, IKKβ, and IKKγ) among the sham, CME, and control siRNA groups. This study demonstrates, for the first time, that the PTEN/Akt signaling pathway contributes to cardiomyocyte apoptosis. The data generated from this study provide a rationale for the development of PTEN-based therapeutic strategies for CME-induced myocardial injury. © The Author(s) 2016.

PTENα, a PTEN isoform translated through alternative initiation, regulates mitochondrial function and energy metabolism.

PubMed

Liang, Hui; He, Shiming; Yang, Jingyi; Jia, Xinying; Wang, Pan; Chen, Xi; Zhang, Zhong; Zou, Xiajuan; McNutt, Michael A; Shen, Wen Hong; Yin, Yuxin

2014-05-06

PTEN is one of the most frequently mutated genes in human cancer. It is known that PTEN has a wide range of biological functions beyond tumor suppression. Here, we report that PTENα, an N-terminally extended form of PTEN, functions in mitochondrial metabolism. Translation of PTENα is initiated from a CUG codon upstream of and in-frame with the coding region of canonical PTEN. Eukaryotic translation initiation factor 2A (eIF2A) controls PTENα translation, which requires a CUG-centered palindromic motif. We show that PTENα induces cytochrome c oxidase activity and ATP production in mitochondria. TALEN-mediated somatic deletion of PTENα impairs mitochondrial respiratory chain function. PTENα interacts with canonical PTEN to increase PINK1 protein levels and promote energy production. Our studies demonstrate the importance of eIF2A-mediated alternative translation for generation of protein diversity in eukaryotic systems and provide insights into the mechanism by which the PTEN family is involved in multiple cellular processes. Copyright © 2014 Elsevier Inc. All rights reserved.

PTEN is a protein phosphatase that targets active PTK6 and inhibits PTK6 oncogenic signaling in prostate cancer.

PubMed

Wozniak, Darren J; Kajdacsy-Balla, Andre; Macias, Virgilia; Ball-Kell, Susan; Zenner, Morgan L; Bie, Wenjun; Tyner, Angela L

2017-11-15

PTEN activity is often lost in prostate cancer. We show that the tyrosine kinase PTK6 (BRK) is a PTEN substrate. Phosphorylation of PTK6 tyrosine 342 (PY342) promotes activation, while phosphorylation of tyrosine 447 (PY447) regulates auto-inhibition. Introduction of PTEN into a PTEN null prostate cancer cell line leads to dephosphorylation of PY342 but not PY447 and PTK6 inhibition. Conversely, PTEN knockdown promotes PTK6 activation in PTEN positive cells. Using a variety of PTEN mutant constructs, we show that protein phosphatase activity of PTEN targets PTK6, with efficiency similar to PTP1B, a phosphatase that directly dephosphorylates PTK6 Y342. Conditional disruption of Pten in the mouse prostate leads to tumorigenesis and increased phosphorylation of PTK6 Y342, and disruption of Ptk6 impairs tumorigenesis. In human prostate tumor tissue microarrays, loss of PTEN correlates with increased PTK6 PY342 and poor outcome. These data suggest PTK6 activation promotes invasive prostate cancer induced by PTEN loss.

PTEN-mediated ERK1/2 inhibition and paradoxical cellular proliferation following Pnck overexpression

PubMed Central

Deb, Tushar B; Barndt, Robert J; Zuo, Annie H; Sengupta, Surojeet; Coticchia, Christine M; Johnson, Michael D

2014-01-01

Pregnancy upregulated non-ubiquitous calmodulin kinase (Pnck), a novel calmodulin kinase, is significantly overexpressed in breast and renal cancers. We present evidence that at high cell density, overexpression of Pnck in HEK 293 cells inhibits serum-induced extracellular signal-regulated kinase (ERK1/ERK2) activation. ERK1/2 inhibition is calcium-dependent and Pnck kinase activity is required for ERK1/2 inhibition, since expression of a kinase-dead (K44A) and a catalytic loop phosphorylation mutant (T171A) Pnck protein is unable to inhibit ERK 1/2 activity. Ras is constitutively active at high cell density, and Pnck does not alter Ras activation, suggesting that Pnck inhibition of ERK1/2 activity is independent of Ras activity. Pnck inhibition of serum-induced ERK1/2 activity is lost in cells in which phosphatase and tensin homolog (PTEN) is suppressed, suggesting that Pnck inhibition of ERK1/2 activity is mediated by PTEN. Overexpression of protein phosphatase-active but lipid phosphatase-dead PTEN protein inhibits ERK1/2 activity in control cells and enhances Pnck-mediated ERK1/2 inhibition, suggesting that Pnck increases availability of protein phosphatase active PTEN for ERK1/2 inhibition. Pnck is a stress-responsive kinase; however, serum-induced p38 MAP kinase activity is also downregulated by Pnck in a Pnck kinase- and PTEN-dependent manner, similar to ERK1/2 inhibition. Pnck overexpression increases proliferation, which is inhibited by PTEN knockdown, implying that PTEN acts as a paradoxical promoter of proliferation in ERK1/2 and p38 MAP kinase phosphorylation-inhibited, Pnck-overexpressing cells. Overall, these data reveal a novel function of Pnck in the regulation of ERK1/2 and p38 MAP kinase activity and cell proliferation, which is mediated by paradoxical PTEN functions. The possible biological implications of these data are discussed. PMID:24552815

Loss of PTEN causes SHP2 activation, making lung cancer cells unresponsive to IFN-γ

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chen, Chia-Ling; Chiang, Tzu-Hui; Tseng, Po-Chun

Src homology-2 domain-containing phosphatase (SHP) 2, an oncogenic phosphatase, inhibits type II immune interferon (IFN)-γ signaling by subverting signal transducers and activators of transcription 1 tyrosine phosphorylation and activation. For cancer immunoediting, this study aimed to investigate the decrease of phosphatase and tensin homolog deleted on chromosome 10 (PTEN), a tumor suppressor protein, leading to cellular impairment of IFN-γ signaling. In comparison with human lung adenocarcinoma A549 cells, the natural PTEN loss in another human lung adenocarcinoma line, PC14PE6/AS2 cells, presents reduced responsiveness in IFN-γ-induced IFN regulatory factor 1 activation and CD54 expression. Artificially silencing PTEN expression in A549 cellsmore » also caused cells to be unresponsive to IFN-γ without affecting IFN-γ receptor expression. IFN-γ-induced inhibition of cell proliferation and cytotoxicity were demonstrated in A549 cells but were defective in PC14PE6/AS2 cells and in PTEN-deficient A549 cells. Aberrant activation of SHP2 by ROS was specifically shown in PC14PE6/AS2 cells and PTEN-deficient A549 cells. Inhibiting ROS and SHP2 rescued cellular responses to IFN-γ-induced cytotoxicity and inhibition of cell proliferation in PC14PE6/AS2 cells. These results demonstrate that a decrease in PTEN facilitates ROS/SHP2 signaling, causing lung cancer cells to become unresponsive to IFN-γ. - Highlights: • This study demonstrates that PTEN decrease causes cellular unresponsive to IFN-γ. • Lung cancer cells with PTEN deficiency show unresponsive to IFN-γ signaling. • PTEN decrease inhibits IFN-γ-induced CD54, cell proliferation inhibition, and cytotoxicity. • ROS-mediated SHP2 activation makes PTEN-deficient cells unresponsive to IFN-γ.« less

Formononetin inhibits human bladder cancer cell proliferation and invasiveness via regulation of miR-21 and PTEN.

PubMed

Wu, Yiying; Zhang, Xing; Li, Zhengzhao; Yan, Haibiao; Qin, Jian; Li, Tianyu

2017-03-22

The isoflavone formononetin is the main active component of Astragalus membranaceus and possesses anti-tumorigenic properties. However, the role of formononetin in human bladder cancer (BCa) has not been fully elucidated. The aim of the present study was to investigate the anti-tumor effects of formononetin on BCa cells and its potential molecular mechanism. T24 cells were treated with different concentrations of formononetin, and then the cell proliferation was assessed by MTT assay, cell apoptosis by Hoechst 33258 stain assay, cell invasiveness by transwell invasion assay, microRNA-21 (miR-21) expression by real-time PCR and the protein level of phosphatase and tensin homolog (PTEN) and phosphorylated homolog of Akt (p-Akt) by western blotting. The results showed that formononetin significantly inhibited the proliferation of T24 cells in a time- and dose-dependent manner. T24 cells treated with formononetin displayed obvious morphological changes of apoptosis and lower invasiveness. In addition, miR-21 expression was significantly decreased in formononetin-treated T24 cells, followed by increase of PTEN, and down-regulation of p-Akt. Collectively, these results suggest that formononetin exerts an anti-carcinogenic effect on BCa in vitro, which might be due to miR-21-mediated regulation of the PTEN/Akt pathway.

ATM inhibition induces synthetic lethality and enhances sensitivity of PTEN-deficient breast cancer cells to cisplatin.

PubMed

Li, Ke; Yan, Huaying; Guo, Wenhao; Tang, Mei; Zhao, Xinyu; Tong, Aiping; Peng, Yong; Li, Qintong; Yuan, Zhu

2018-05-01

PTEN deficiency often causes defects in DNA damage repair. Currently, effective therapies for breast cancer are lacking. ATM is an attractive target for cancer treatment. Previous studies suggested a synthetic lethality between PTEN and PARP. However, the synthetically lethal interaction between PTEN and ATM in breast cancer has not been reported. Moreover, the mechanism remains elusive. Here, using KU-60019, an ATM kinase inhibitor, we investigated ATM inhibition as a synthetically lethal strategy to target breast cancer cells with PTEN defects. We found that KU-60019 preferentially sensitizes PTEN-deficient MDA-MB-468 breast cancer cells to cisplatin, though it also slightly enhances sensitivity of PTEN wild-type breast cancer cells. The increased cytotoxic sensitivity is associated with apoptosis, as evidenced by flow cytometry and PARP cleavage. Additionally, the increase of DNA damage accumulation due to the decreased capability of DNA repair, as indicated by γ-H2AX and Rad51 foci, also contributed to this selective cytotoxicity. Mechanistically, compared with PTEN wild-type MDA-MB-231 cells, PTEN-deficient MDA-MB-468 cells have lower level of Rad51, higher ATM kinase activity, and display the elevated level of DNA damage. Moreover, these differences could be further enlarged by cisplatin. Our findings suggest that ATM is a promising target for PTEN-defective breast cancer. Copyright © 2018 Elsevier Inc. All rights reserved.

Propylthiouracil, independent of its antithyroid effect, promotes vascular smooth muscle cells differentiation via PTEN induction.

PubMed

Chen, Wei-Jan; Pang, Jong-Hwei S; Lin, Kwang-Huei; Lee, Dany-Young; Hsu, Lung-An; Kuo, Chi-Tai

2010-01-01

Propylthiouracil (PTU), independent of its antithyroid effect, is recently found to have an antiatherosclerotic effect. The aim of this study is to determine the impact of PTU on phenotypic modulation of vascular smooth muscle cells (VSMCs), as phenotypic modulation may contribute to the growth of atherosclerotic lesions and neointimal formation after arterial injury. Propylthiouracil reduced neointimal formation in balloon-injured rat carotid arteries. In vitro, PTU may convert VSMCs from a serum-induced dedifferentiation state to a differentiated state, as indicated by a spindle-shaped morphology and an increase in the expression of SMC differentiation marker contractile proteins, including calponin and smooth muscle (SM)-myosin heavy chain (SM-MHC). Transient transfection studies in VSMCs demonstrated that PTU induced the activity of SMC marker genes (calponin and SM-MHC) promoters, indicating that PTU up-regulates these genes expression predominantly at the transcriptional level. Furthermore, PTU enhanced the expression of PTEN and inhibition of PTEN by siRNA knockdown blocked PTU-induced activation of contractile proteins expression and promoter activity. In the rat carotid injury model, PTU reversed the down-regulation of contractile proteins and up-regulated PTEN in the neointima induced by balloon injury. Propylthiouracil promotes VSMC differentiation, at lest in part, via induction of the PTEN-mediated pathway. These findings suggest a possible mechanism by which PTU may contribute to its beneficial effects on atherogenesis and neointimal formation after arterial injury.

Spectrum of somatic EGFR, KRAS, BRAF, PTEN mutations and TTF-1 expression in Brazilian lung cancer patients.

PubMed

Carneiro, Juliana G; Couto, Patricia G; Bastos-Rodrigues, Luciana; Bicalho, Maria Aparecida C; Vidigal, Paula V; Vilhena, Alyne; Amaral, Nilson F; Bale, Allen E; Friedman, Eitan; De Marco, Luiz

2014-01-01

Lung cancer is the leading global cause of cancer-related mortality. Inter-individual variability in treatment response and prognosis has been associated with genetic polymorphisms in specific genes: EGFR, KRAS, BRAF, PTEN and TTF-1. Somatic mutations in EGFR and KRAS genes are reported at rates of 15-40% in non-small cell lung cancer (NSCLC) in ethnically diverse populations. BRAF and PTEN are commonly mutated genes in various cancer types, including NSCLC, with PTEN mutations exerting an effect on the therapeutic response of EGFR/AKT/PI3K pathway inhibitors. TTF-1 is expressed in approximately 80% of lung adenocarcinomas and its positivity correlates with higher prevalence of EGFR mutation in this cancer type. To determine molecular markers for lung cancer in Brazilian patients, the rate of the predominant EGFR, KRAS, BRAF and PTEN mutations, as well as TTF-1 expression, was assessed in 88 Brazilian NSCLC patients. EGFR exon 19 deletions (del746-750) were detected in 3/88 (3·4%) patients. Activating KRAS mutations in codons 12 and 61 were noted in five (5·7%) and two (2·3%) patients, respectively. None of the common somatic mutations were detected in either the BRAF or PTEN genes. TTF-1 was overexpressed in 40·7% of squamous-cell carcinoma (SCC). Our findings add to a growing body of data that highlights the genetic heterogeneity of the abnormal EGFR pathway in lung cancer among ethnically diverse populations.

The Chaperone-assisted E3 Ligase C Terminus of Hsc70-interacting Protein (CHIP) Targets PTEN for Proteasomal Degradation*

PubMed Central

Ahmed, Syed Feroj; Deb, Satamita; Paul, Indranil; Chatterjee, Anirban; Mandal, Tapashi; Chatterjee, Uttara; Ghosh, Mrinal K.

2012-01-01

The tumor suppressor, PTEN is key to the regulation of diverse cellular processes, making it a prime candidate to be tightly regulated. The PTEN level is controlled in a major way by E3 ligase-mediated degradation through the Ubiquitin-Proteasome System (UPS). Nedd 4-1, XIAP, and WWP2 have been shown to maintain PTEN turnover. Here, we report that CHIP, the chaperone-associated E3 ligase, induces ubiquitination and regulates the proteasomal turnover of PTEN. It was apparent from our findings that PTEN transiently associates with the molecular chaperones and thereby gets diverted to the degradation pathway through its interaction with CHIP. The TPR domain of CHIP and parts of the N-terminal domain of PTEN are required for their interaction. Overexpression of CHIP leads to elevated ubiquitination and a shortened half-life of endogenous PTEN. On the other hand, depletion of endogenous CHIP stabilizes PTEN. CHIP is also shown to regulate PTEN-dependent transcription presumably through its down-regulation. PTEN shared an inverse correlation with CHIP in human prostate cancer patient samples, thereby triggering the prospects of a more complex mode of PTEN regulation in cancer. PMID:22427670

A study of the dynamics of PTEN proteins in living cells using in vivo fluorescence correlation spectroscopy

NASA Astrophysics Data System (ADS)

Du, Zhixue; Dong, Chaoqing; Ren, Jicun

2017-06-01

PTEN (phosphatase and tensin homolog on chromosome 10) is one of the most important tumor-suppressor proteins, which plays a key role in negative regulation of the PI3K/AKT pathway, and governs many cellular processes including growth, proliferation, survival and migration. The dynamics of PTEN proteins in single living cells is as yet unclear owing to a shortage of suitable in vivo approaches. Here, we report a single-molecule method for in vivo study of the dynamics of PTEN proteins in living cells using fluorescence correlation spectroscopy (FCS). First, we established a monoclonal H1299 stable cell line expressing enhanced green fluorescent protein (EGFP) and PTEN (EGFP-PTEN) fusion proteins; we then developed an in vivo FCS method to study the dynamics of EGFP-PTEN both in the nucleus and the cytoplasm. We investigated the diffusion behaviors of EGFP and EGFP-PTEN in solution, nucleus and cytosol, and observed that the motion of PTEN in living cells was restricted compared with EGFP. Finally, we investigated the protein dynamics in living cells under oxidative stress stimulation and a cellular ATP depletion treatment. Under oxidative stress stimulation, the EGFP-PTEN concentration increased in the nucleus, but slightly decreased in the cytoplasm. The diffusion coefficient and alpha value of EGFP-PTEN reduced significantly both in the nucleus and cytoplasm; the significantly decreased alpha parameter indicates a more restricted Brownian diffusion behavior. Under the cellular ATP depletion treatment, the concentration of EGFP-PTEN remained unchanged in the nucleus and decreased significantly in cytosol. The diffusion coefficient of EGFP-PTEN decreased significantly in cytosol, but showed no significant change in the nucleus; the alpha value decreased significantly in both the nucleus and cytoplasm. These results suggest that the concentration and mobility of PTEN in the nucleus and cytoplasm can be regulated by stimulation methods. Our approach provides a unique

High frequency of coexistent mutations of PIK3CA and PTEN genes in endometrial carcinoma.

PubMed

Oda, Katsutoshi; Stokoe, David; Taketani, Yuji; McCormick, Frank

2005-12-01

The phosphatidylinositol 3'-kinase (PI3K) pathway is activated in many human cancers. In addition to inactivation of the PTEN tumor suppressor gene, mutations or amplifications of the catalytic subunit alpha of PI3K (PIK3CA) have been reported. However, the coexistence of mutations in these two genes seems exceedingly rare. As PTEN mutations occur at high frequency in endometrial carcinoma, we screened 66 primary endometrial carcinomas for mutations in the helical and catalytic domains of PIK3CA. We identified a total of 24 (36%) mutations in this gene and coexistence of PIK3CA/PTEN mutations at high frequency (26%). PIK3CA mutations were more common in tumors with PTEN mutations (17 of 37, 46%) compared with those without PTEN mutations (7 of 29, 24%). Array comparative genomic hybridization detected 3q24-qter amplification, which covers the PIK3CA gene (3q26.3), in one of nine tumors. Knocking down PTEN expression in the HEC-1B cell line, which possesses both K-Ras and PIK3CA mutations, further enhances phosphorylation of Akt (Ser473), indicating that double mutation of PIK3CA and PTEN has an additive effect on PI3K activation. Our data suggest that the PI3K pathway is extensively activated in endometrial carcinomas, and that combination of PIK3CA/PTEN alterations might play an important role in development of these tumors.

Increased plasma levels of FABP4 and PTEN is associated with more severe insulin resistance in women with gestational diabetes mellitus.

PubMed

Li, Yuan-yuan; Xiao, Rui; Li, Cai-ping; Huangfu, Jian; Mao, Jiang-feng

2015-02-08

The aim of this study was to investigate the relationship between plasma fatty acid binding protein 4 (FABP4), phosphatase and tensin homolog (PTEN), and insulin resistance in patients with gestational diabetes mellitus (GDM). Plasma FABP4 and PTEN were determined by ELISA in GDM patients (GDM group, n=30) and in euglycemic pregnant women (control group, n=30). The clinical features, body mass index (BMI), homeostasis model assessment of insulin resistance (HOMA-IR), and lipid profiles were compared between the 2 groups. The influence of risk factors on insulin resistance, including BMI, lipid profiles, FABP4, and PTEN, were further investigated by multiple-factor stepwise regression analysis. Higher levels of BMI, ΔBMI, triglyceride (TG), fasting plasma glucose (FPG), 2-hour plasma glucose (2hPG), fasting insulin, HOMA-IR, FABP4, PTEN, and lower level of high-density lipoprotein cholesterol (HDL-C) were found in the GDM patients than in the controls (all P<0.005). The plasma FABP4 was 1.47±0.25 vs. 0.20±0.07 ng/ml in the GDM and control group, respectively (P<0.0001). Plasma PTEN was 6.46±1.57 vs. 4.72±0.82 ng/ml in the GDM and control group, respectively (P<0.0001). There was a positive relation between plasma FABP4 and PTEN when all blood samples, including GDM and control groups, were analyzed (P<0.05). The multiple-factor regression analysis revealed that plasma FABP4, TG, and PTEN were independent risk factors for increased insulin resistance. GDM patients have more severe insulin resistance compared to euglycemic pregnant women. Higher levels of plasma FABP4 and PTEN are associated with increased insulin resistance and may participate in the pathogenesis of insulin resistance during gestation.

New mutation in the PTEN gene in a Brazilian patient with Cowden's syndrome.

PubMed

Lima, Erika U de; Soares, Iberê C; Danilovic, Debora L S; Marui, Suemi

2012-11-01

Cowden syndrome is characterized by hamartomatous polyps, trichilemmomas, increased risk of developing neoplasms, and is associated with germline mutations in the PTEN gene. We searched for germline mutations in PTEN in a 49-year-old female patient who presented trichilemmoma with previous history of breast carcinoma, and thyroidectomy for a thyroid nodule. We also searched for somatic mutations in breast and thyroid tumoral tissues. DNA was extracted from peripheral leukocytes, paraffin samples of breast carcinoma, and cytological smears of thyroid nodule fine-needle aspiration biopsy, whose final histopathological diagnosis was adenomatous goiter. PTEN was amplified and sequenced. We identified a novel mutation, due to a T>A inversion at position 159 and A>T inversion at position 160, leading to valine-to-aspartic acid substitution at position 53. The p.Val53Asp was also found in homozygous state in samples obtained from adenocarcinoma breast and thyroid biopsy, denoting loss of heterozygosity. Here, we demonstrated a novel germline mutation in PTEN, as well as somatic loss of the wild-type PTEN allele in breast and thyroid tumors in a patient with Cowden syndrome.

Multifocal demyelinating motor neuropathy and hamartoma syndrome associated with a de novo PTEN mutation

PubMed Central

Bansagi, Boglarka; Phan, Vietxuan; Baker, Mark R.; O'Sullivan, Julia; Jennings, Matthew J.; Whittaker, Roger G.; Müller, Juliane S.; Duff, Jennifer; Griffin, Helen; Miller, James A.L.; Gorman, Grainne S.; Lochmüller, Hanns; Chinnery, Patrick F.; Roos, Andreas; Swan, Laura E.

2018-01-01

Objective To describe a patient with a multifocal demyelinating motor neuropathy with onset in childhood and a mutation in phosphatase and tensin homolog (PTEN), a tumor suppressor gene associated with inherited tumor susceptibility conditions, macrocephaly, autism, ataxia, tremor, and epilepsy. Functional implications of this protein have been investigated in Parkinson and Alzheimer diseases. Methods We performed whole-exome sequencing in the patient's genomic DNA validated by Sanger sequencing. Immunoblotting, in vitro enzymatic assay, and label-free shotgun proteomic profiling were performed in the patient's fibroblasts. Results The predominant clinical presentation of the patient was a childhood onset, asymmetric progressive multifocal motor neuropathy. In addition, he presented with macrocephaly, autism spectrum disorder, and skin hamartomas, considered as clinical criteria for PTEN-related hamartoma tumor syndrome. Extensive tumor screening did not detect any malignancies. We detected a novel de novo heterozygous c.269T>C, p.(Phe90Ser) PTEN variant, which was absent in both parents. The pathogenicity of the variant is supported by altered expression of several PTEN-associated proteins involved in tumorigenesis. Moreover, fibroblasts showed a defect in catalytic activity of PTEN against the secondary substrate, phosphatidylinositol 3,4-trisphosphate. In support of our findings, focal hypermyelination leading to peripheral neuropathy has been reported in PTEN-deficient mice. Conclusion We describe a novel phenotype, PTEN-associated multifocal demyelinating motor neuropathy with a skin hamartoma syndrome. A similar mechanism may potentially underlie other forms of Charcot-Marie-Tooth disease with involvement of the phosphatidylinositol pathway. PMID:29720545

Regulation of the activity of the tumor suppressor PTEN by thioredoxin in Drosophila melanogaster

DOE Office of Scientific and Technical Information (OSTI.GOV)

Song, Zuohe; Department of Nutritional Sciences, University of Arizona, 1177 E. 4th Street, Tucson, AZ 85721; Saghafi, Negin

2007-04-01

Human Thioredoxin-1 (hTrx-1) is a small redox protein with a molecular weight of 12 kDa that contains two cysteine residues found in its catalytic site. HTrx-1 plays an important role in cell growth, apoptosis, and cancer patient prognosis. Recently, we have demonstrated that hTrx-1 binds to the C2 domain of the human tumor suppressor, PTEN, in a redox dependent manner. This binding leads to the inhibition of PTEN lipid phosphatase activity in mammalian tissue culture systems. In this study, we show that over-expression of hTrx-1 in Drosophila melanogaster promotes cell growth and proliferation during eye development as measured by eyemore » size and ommatidia size. Furthermore, hTrx-1 rescues the small eye phenotype induced by the over-expression of PTEN. We demonstrate that this rescue of the PTEN-induced eye size phenotype requires cysteine-218 in the C2 domain of PTEN. We also show that hTrx-1 over-expression results in increased Akt phosphorylation in fly head extracts supporting our observations that the hTrx-1-induced eye size increase results from the inhibition of PTEN activity. Our study confirms the redox regulation of PTEN through disulfide bond formation with the hTrx-1 in Drosophila and suggests conserved mechanisms for thioredoxins and their interactions with the phosphatidylinositol-3-kinase signaling pathway in humans and fruit flies.« less

Cisplatin-induced caspase activation mediates PTEN cleavage in ovarian cancer cells: a potential mechanism of chemoresistance.

PubMed

Singh, Mohan; Chaudhry, Parvesh; Fabi, Francois; Asselin, Eric

2013-05-10

The phosphatase and tensin homolog deleted on chromosome 10 (PTEN) tumor suppressor protein is a central negative regulator of the PI3K/AKT signaling cascade and suppresses cell survival as well as cell proliferation. PTEN is found to be either inactivated or mutated in various human malignancies. In the present study, we have investigated the regulation of PTEN during cisplatin induced apoptosis in A2780, A270-CP (cisplatin resistant), OVCAR-3 and SKOV3 ovarian cancer cell lines. Cells were treated with 10μM of cisplatin for 24h. Transcript and protein levels were analysed by quantitative reverse transcriptase-polymerase chain reaction (qRT-PCR) and western blotting, respectively. Immunofluorescence microscopy was used to assess the intracellular localization of PTEN. Proteasome inhibitor and various caspases inhibitors were used to find the mechanism of PTEN degradation. PTEN protein levels were found to be decreased significantly in A2780 cells; however, there was no change in PTEN protein levels in A2780-CP, OVCAR-3 and SKOV3 cells with cisplatin treatment. The decrease in PTEN protein was accompanied with an increase in the levels of AKT phosphorylation (pAKT) in A2780 cells and a decrease of BCL-2. Cisplatin treatment induced the activation/cleavage of caspase-3, -6, -7, -8, -9 in all cell lines tested in this study except the resistant variant A2780-CP cells. In A2780 cells, restoration of PTEN levels was achieved upon pre-treatment with Z-DEVD-FMK (broad range caspases inhibitor) and not with MG132 (proteasome inhibitor) and by overexpression of BCL-2, suggesting that caspases and BCL-2 are involved in the decrease of PTEN protein levels in A2780 cells. The decrease in pro-apoptotic PTEN protein levels and increase in survival factor pAKT in A2780 ovarian cancer cells suggest that cisplatin treatment could further exacerbate drug resistance in A2780 ovarian cancer cells.

FGFR and PTEN signaling interact during lens development to regulate cell survival

PubMed Central

Chaffee, Blake R.; Hoang, Thanh V.; Leonard, Melissa R.; Bruney, Devin G.; Wagner, Brad D.; Dowd, Joseph Richard; Leone, Gustavo; Ostrowski, Michael C.; Robinson, Michael L.

2016-01-01

Lens epithelial cells express many receptor tyrosine kinases (RTKs) that stimulate PI3K-AKT and RAS-RAF-MEK-ERK intracellular signaling pathways. These pathways ultimately activate the phosphorylation of key cellular transcription factors and other proteins that control proliferation, survival, metabolism, and differentiation in virtually all cells. Among RTKs in the lens, only stimulation of fibroblast growth factor receptors (FGFRs) elicits a lens epithelial cell to fiber cell differentiation response in mammals. Moreover, although the lens expresses three different Fgfr genes, the isolated removal of Fgfr2 at the lens placode stage inhibits both lens cell survival and fiber cell differentiation. Phosphatase and tensin homolog (PTEN), commonly known as a tumor suppressor, inhibits ERK and AKT activation and initiates both apoptotic pathways, and cell cycle arrest. Here, we show that the combined deletion of Fgfr2 and Pten rescues the cell death phenotype associated with Fgfr2 loss alone. Additionally, Pten removal increased AKT and ERK activation, above the levels of controls, in the presence or absence of Fgfr2. However, isolated deletion of Pten failed to stimulate ectopic fiber cell differentiation, and the combined deletion of Pten and Fgfr2 failed to restore differentiation-specific Aquaporin0 and DnaseIIβ expression in the lens fiber cells. PMID:26764128

Downregulation of Hsp27 (HSPB1) in MCF-7 human breast cancer cells induces upregulation of PTEN.

PubMed

Cayado-Gutiérrez, Niubys; Moncalero, Vera L; Rosales, Eliana M; Berón, Walter; Salvatierra, Edgardo E; Alvarez-Olmedo, Daiana; Radrizzani, Martín; Ciocca, Daniel R

2013-03-01

Hsp27 (HSPB1) is usually overexpressed in breast cancers affecting the disease outcome and the sensitivity of tumors to chemotherapy and radiotherapy. Hsp27 interacts with other proteins such as β-catenin, histone deacetylase HDAC6, transcription factor STAT2 and procaspase-3. Phosphatase and tensin homologue (PTEN) is a tumor suppressor gene that is deleted in many human tumors. The PI3K/Akt signaling pathway is negatively regulated by PTEN. Hsp27 is described as a key component of the Akt signaling cascade: Akt, BAD, Forkhead transcription factors, Hsp27, mitogen-activated protein kinase kinase-3 and -6. Here, we have examined whether the downregulation of Hsp27 by siHsp27 affects the PTEN levels in the MCF-7 human breast cancer cell line. PTEN was detected with two different antibodies using western blots and immunocytochemistry. p-Akt was also evaluated by western blot. In addition, Hsp27 and PTEN were immunoprecipitated to know whether these proteins interact. Intracellular colocalization studies were carried out by confocal microscopy. A significant reduction in the Hsp27 levels was noted in the siHsp27 transfected cells. These Hsp27 downregulated cells showed a significant increased expression of PTEN. The MW 76 and 55 kDa PTEN forms were upregulated as revealed by two different antibodies. The phosphatase activity of PTEN seems to be active because p-Akt levels were reduced. Hsp27 immunoprecipitation was bringing PTEN and vice versa, these two proteins seem to interact at cytoplasmic level by FRET. Downregulation of Hsp27 stabilized PTEN protein levels. Chaperone-assisted E3 ligase C terminus of Hsc70-interacting protein (CHIP) levels were not significantly influenced by Hsp27 downregulation. In conclusion, we report a novel function of Hsp27 modulating the PTEN levels in human breast cancer cells suggesting an interaction between these two molecules.

Synergistic action of Smad4 and Pten in suppressing pancreatic ductal adenocarcinoma formation in mice.

PubMed

Xu, X; Ehdaie, B; Ohara, N; Yoshino, T; Deng, C-X

2010-02-04

Mutations of SMAD4/DPC4 are found in about 60% of human invasive pancreatic ductal adenocarcinomas (PDACs); yet, the manner in which SMAD4 deficiency enhances tumorigenesis remains elusive. Using a Cre-LoxP approach, we generated a mutant mouse carrying a targeted deletion of Smad4 in the pancreas. We showed that the absence of Smad4 alone did not trigger pancreas tumor formation; however, it increased the expression of an inactivated form of Pten, suggesting a role of Pten in preventing Smad4-/- cells from undergoing malignancy. To investigate this, we disrupted both Pten and Smad4. We showed that Pten deficiency initiated widespread premalignant lesions, and a low tumor incidence that was significantly accelerated by Smad4-deficiency. The absence of Smad4 in a Pten-mutant background enhanced cell proliferation and triggered transdifferentiation from acinar, centroacinar and islet cells, accompanied by activation of Notch1 signaling. We showed that all tumors developed in the Smad4/Pten-mutant pancreas exhibited high levels of pAKT and mTOR, and that about 50 and 83% of human pancreatic cancers examined showed increased pAKT and pmTOR, respectively. Besides the similarity in gene expression, the pAKT and/or pmTOR-positive human PDACs and mouse pancreatic tumors also shared some histopathological similarities. These observations indicate that Smad4/Pten-mutant mice mimic the tumor progression of human pancreatic cancers that are driven by activation of the AKT-mTOR pathway, and uncovered a synergistic action of Smad4 and Pten in repressing pancreatic tumorigenesis.

High-calorie diet exacerbates prostate neoplasia in mice with haploinsufficiency of Pten tumor suppressor gene.

PubMed

Liu, Jehnan; Ramakrishnan, Sadeesh K; Khuder, Saja S; Kaw, Meenakshi K; Muturi, Harrison T; Lester, Sumona Ghosh; Lee, Sang Jun; Fedorova, Larisa V; Kim, Andrea J; Mohamed, Iman E; Gatto-Weis, Cara; Eisenmann, Kathryn M; Conran, Philip B; Najjar, Sonia M

2015-03-01

Association between prostate cancer and obesity remains controversial. Allelic deletions of PTEN, a tumor suppressor gene, are common in prostate cancer in men. Monoallelic Pten deletion in mice causes low prostatic intraepithelial neoplasia (mPIN). This study tested the effect of a hypercaloric diet on prostate cancer in Pten (+/-) mice. 1-month old mice were fed a high-calorie diet deriving 45% calories from fat for 3 and 6 months before prostate was analyzed histologically and biochemically for mPIN progression. Because Pten (+/-) mice are protected against diet-induced insulin resistance, we tested the role of insulin on cell growth in RWPE-1 normal human prostatic epithelial cells with siRNA knockdown of PTEN. In addition to activating PI3 kinase/Akt and Ras/MAPkinase pathways, high-calorie diet causes neoplastic progression, angiogenesis, inflammation and epithelial-mesenchymal transition. It also elevates the expression of fatty acid synthase (FAS), a lipogenic gene commonly elevated in progressive cancer. SiRNA-mediated downregulation of PTEN demonstrates increased cell growth and motility, and soft agar clonicity in addition to elevation in FAS in response to insulin in RWPE-1 normal human prostatic cells. Downregulating FAS in addition to PTEN, blunted the proliferative effect of insulin (and IL-6) in RWPE-1 cells. High-calorie diet promotes prostate cancer progression in the genetically susceptible Pten haploinsufficient mouse while preserving insulin sensitivity. This appears to be partly due to increased inflammatory response to high-caloric intake in addition to increased ability of insulin to promote lipogenesis.

Differential Association of Phosphatidylinositol 3-Kinase, SHIP-1, and PTEN with Forming Phagosomes

PubMed Central

Kamen, Lynn A.; Levinsohn, Jonathan

2007-01-01

In macrophages, enzymes that synthesize or hydrolyze phosphatidylinositol (3,4,5)-trisphosphate [PI(3,4,5)P3] regulate Fcγ receptor-mediated phagocytosis. Inhibition of phosphatidylinositol 3-kinase (PI3K) or overexpression of the lipid phosphatases phosphatase and tensin homologue (PTEN) and Src homology 2 domain-containing inositol phosphatase (SHIP-1), which hydrolyze PI(3,4,5)P3 to phosphatidylinositol 4,5-bisphosphate and phosphatidylinositol 3,4-bisphosphate [PI(3,4)P2], respectively, inhibit phagocytosis in macrophages. To examine how these enzymes regulate phagosome formation, the distributions of yellow fluorescent protein (YFP) chimeras of enzymes and pleckstrin homology (PH) domains specific for their substrates and products were analyzed quantitatively. PTEN-YFP did not localize to phagosomes, suggesting that PTEN regulates phagocytosis globally within the macrophage. SHIP1-YFP and p85-YFP were recruited to forming phagosomes. SHIP1-YFP sequestered to the leading edge and dissociated from phagocytic cups earlier than did p85-cyan fluorescent protein, indicating that SHIP-1 inhibitory activities are restricted to the early stages of phagocytosis. PH domain chimeras indicated that early during phagocytosis, PI(3,4,5)P3 was slightly more abundant than PI(3,4)P2 at the leading edge of the forming cup. These results support a model in which phagosomal PI3K generates PI(3,4,5)P3 necessary for later stages of phagocytosis, PTEN determines whether those late stages can occur, and SHIP-1 regulates when and where they occur by transiently suppressing PI(3,4,5)P3-dependent activities necessary for completion of phagocytosis. PMID:17442886

Cooperativity Between Oncogenic PKC Epsilon and Pten Loss in Prostate Cancer Progression

DTIC Science & Technology

2016-10-01

objective of our studies is to elucidate the mechanisms by which PKCε, in conjunction with Pten loss, lead to malignant transformation and metastasis...ligand for the G-protein-coupled receptor CXCR5. This led us to hypothesize that PKCε in conjunction Pten deficienty activate an autonomous autocrine

Reduced expression levels of PTEN are associated with decreased sensitivity of HCC827 cells to icotinib.

PubMed

Zhai, Yang; Zhang, Yanjun; Nan, Kejun; Liang, Xuan

2017-05-01

The clinical resistance of non-small cell lung cancer (NSCLC) to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) has been linked to EGFR T790M resistance mutations or MET amplifications. Additional mechanisms underlying EGFR-TKI drug resistance remain unclear. The present study demonstrated that icotinib significantly inhibited the proliferation and increased the apoptosis rate of HCC827 cells; the cellular mRNA and protein expression levels of phosphatase and tensin homolog (PTEN) were also significantly downregulated. To investigate the effect of PTEN expression levels on the sensitivity of HCC827 cells to icotinib, PTEN expression was silenced using a PTEN-specific small interfering RNA. The current study identified that the downregulation of PTEN expression levels may promote cellular proliferation in addition to decreasing the apoptosis of HCC827 cells, and may reduce the sensitivity of HCC827 cells to icotinib. These results suggested that reduced PTEN expression levels were associated with the decreased sensitivity of HCC827 cells to icotinib. Furthermore, PTEN expression levels may be a useful marker for predicting icotinib resistance and elucidating the resistance mechanisms underlying EGFR-mutated NSCLC.

Reduced expression levels of PTEN are associated with decreased sensitivity of HCC827 cells to icotinib

PubMed Central

Zhai, Yang; Zhang, Yanjun; Nan, Kejun; Liang, Xuan

2017-01-01

The clinical resistance of non-small cell lung cancer (NSCLC) to epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) has been linked to EGFR T790M resistance mutations or MET amplifications. Additional mechanisms underlying EGFR-TKI drug resistance remain unclear. The present study demonstrated that icotinib significantly inhibited the proliferation and increased the apoptosis rate of HCC827 cells; the cellular mRNA and protein expression levels of phosphatase and tensin homolog (PTEN) were also significantly downregulated. To investigate the effect of PTEN expression levels on the sensitivity of HCC827 cells to icotinib, PTEN expression was silenced using a PTEN-specific small interfering RNA. The current study identified that the downregulation of PTEN expression levels may promote cellular proliferation in addition to decreasing the apoptosis of HCC827 cells, and may reduce the sensitivity of HCC827 cells to icotinib. These results suggested that reduced PTEN expression levels were associated with the decreased sensitivity of HCC827 cells to icotinib. Furthermore, PTEN expression levels may be a useful marker for predicting icotinib resistance and elucidating the resistance mechanisms underlying EGFR-mutated NSCLC. PMID:28521430

A PI3K p110β-Rac signalling loop mediates Pten-loss-induced perturbation of haematopoiesis and leukaemogenesis.

PubMed

Yuzugullu, Haluk; Baitsch, Lukas; Von, Thanh; Steiner, Allison; Tong, Haoxuan; Ni, Jing; Clayton, Linda K; Bronson, Roderick; Roberts, Thomas M; Gritsman, Kira; Zhao, Jean J

2015-10-07

The tumour suppressor PTEN, which antagonizes PI3K signalling, is frequently inactivated in haematologic malignancies. In mice, deletion of PTEN in haematopoietic stem cells (HSCs) causes perturbed haematopoiesis, myeloproliferative neoplasia (MPN) and leukaemia. Although the roles of the PI3K isoforms have been studied in PTEN-deficient tumours, their individual roles in PTEN-deficient HSCs are unknown. Here we show that when we delete PTEN in HSCs using the Mx1-Cre system, p110β ablation prevents MPN, improves HSC function and suppresses leukaemia initiation. Pharmacologic inhibition of p110β in PTEN-deficient mice recapitulates these genetic findings, but suggests involvement of both Akt-dependent and -independent pathways. Further investigation reveals that a p110β-Rac signalling loop plays a critical role in PTEN-deficient HSCs. Together, these data suggest that myeloid neoplasia driven by PTEN loss is dependent on p110β via p110β-Rac-positive-feedback loop, and that disruption of this loop may offer a new and effective therapeutic strategy for PTEN-deficient leukaemia.

P-TEN, the tumor suppressor from human chromosome 10q23, is a dual-specificity phosphatase

PubMed Central

Myers, Michael P.; Stolarov, Javor P.; Eng, Charis; Li, Jing; Wang, Steven I.; Wigler, Michael H.; Parsons, Ramon; Tonks, Nicholas K.

1997-01-01

Protein tyrosine phosphatases (PTPs) have long been thought to play a role in tumor suppression due to their ability to antagonize the growth promoting protein tyrosine kinases. Recently, a candidate tumor suppressor from 10q23, termed P-TEN, was isolated, and sequence homology was demonstrated with members of the PTP family, as well as the cytoskeletal protein tensin. Here we show that recombinant P-TEN dephosphorylated protein and peptide substrates phosphorylated on serine, threonine, and tyrosine residues, indicating that P-TEN is a dual-specificity phosphatase. In addition, P-TEN exhibited a high degree of substrate specificity, showing selectivity for extremely acidic substrates in vitro. Furthermore, we demonstrate that mutations in P-TEN, identified from primary tumors, tumor cells lines, and a patient with Bannayan–Zonana syndrome, resulted in the ablation of phosphatase activity, demonstrating that enzymatic activity of P-TEN is necessary for its ability to function as a tumor suppressor. PMID:9256433

Interaction of the androgen receptor, ETV1 and PTEN pathways in mouse prostate varies with pathological stage and predicts cancer progression

PubMed Central

Higgins, Jake; Brogley, Michele; Palanisamy, Nallasivam; Mehra, Rohit; Ittmann, Michael M.; Li, Jun Z.; Tomlins, Scott A.; Robins, Diane M.

2015-01-01

To examine the impact of common somatic mutations in prostate cancer (PCa) on androgen receptor (AR) signaling, mouse models were designed to perturb sequentially the AR, ETV1 and PTEN pathways. Mice with "humanized" AR (hAR) alleles that modified AR transcriptional strength by varying polyglutamine tract (Q-tract) length were crossed with mice expressing a prostate-specific, AR-responsive ETV1 transgene (ETV1Tg). While hAR allele did not grossly affect ETV1-induced neoplasia, ETV1 strongly antagonized global AR regulation and repressed critical androgen-induced differentiation and tumor suppressor genes, such as Nkx3-1 and Hoxb13. When Pten was varied to determine its impact on disease progression, mice lacking one Pten allele (Pten+/−) developed more frequent prostatic intraepithelial neoplasia (PIN). Yet only those with the ETV1 transgene progressed to invasive adenocarcinoma. Furthermore, progression was more frequent with the short Q-tract (stronger) AR, suggesting that the AR, ETV1 and PTEN pathways cooperate in aggressive disease. On the Pten+/− background, ETV1 had markedly less effect on AR target genes. However, a strong inflammatory gene expression signature, notably upregulation of Cxcl16, was induced by ETV1. Comparison of mouse and human patient data stratified by presence of ETS fusion genes highlighted additional factors, some not previously associated with prostate cancer but for which targeted therapies are in development for other diseases. In sum, concerted use of these mouse models illuminates the complex interplay of AR, ETV1 and PTEN pathways in pre-cancerous neoplasia and early tumorigenesis, disease stages difficult to analyze in man. PMID:25631336

Multifocal demyelinating motor neuropathy and hamartoma syndrome associated with a de novo PTEN mutation.

PubMed

Bansagi, Boglarka; Phan, Vietxuan; Baker, Mark R; O'Sullivan, Julia; Jennings, Matthew J; Whittaker, Roger G; Müller, Juliane S; Duff, Jennifer; Griffin, Helen; Miller, James A L; Gorman, Grainne S; Lochmüller, Hanns; Chinnery, Patrick F; Roos, Andreas; Swan, Laura E; Horvath, Rita

2018-05-22

To describe a patient with a multifocal demyelinating motor neuropathy with onset in childhood and a mutation in phosphatase and tensin homolog ( PTEN ), a tumor suppressor gene associated with inherited tumor susceptibility conditions, macrocephaly, autism, ataxia, tremor, and epilepsy. Functional implications of this protein have been investigated in Parkinson and Alzheimer diseases. We performed whole-exome sequencing in the patient's genomic DNA validated by Sanger sequencing. Immunoblotting, in vitro enzymatic assay, and label-free shotgun proteomic profiling were performed in the patient's fibroblasts. The predominant clinical presentation of the patient was a childhood onset, asymmetric progressive multifocal motor neuropathy. In addition, he presented with macrocephaly, autism spectrum disorder, and skin hamartomas, considered as clinical criteria for PTEN-related hamartoma tumor syndrome. Extensive tumor screening did not detect any malignancies. We detected a novel de novo heterozygous c.269T>C, p.(Phe90Ser) PTEN variant, which was absent in both parents. The pathogenicity of the variant is supported by altered expression of several PTEN-associated proteins involved in tumorigenesis. Moreover, fibroblasts showed a defect in catalytic activity of PTEN against the secondary substrate, phosphatidylinositol 3,4-trisphosphate. In support of our findings, focal hypermyelination leading to peripheral neuropathy has been reported in PTEN-deficient mice. We describe a novel phenotype, PTEN-associated multifocal demyelinating motor neuropathy with a skin hamartoma syndrome. A similar mechanism may potentially underlie other forms of Charcot-Marie-Tooth disease with involvement of the phosphatidylinositol pathway. Copyright © 2018 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the American Academy of Neurology.

[Generation and comparison of two genetically engineered mouse models of ErbB2/Neu positive-PTEN deficient breast cancer].

PubMed

Wang, Qing-fei; Ding, Hui; Liu, Bao-rui; Zhang, Kui

2014-07-01

To generate two genetically engineered mouse models of ErbB2/Neu positive-PTEN deficient breast cancer and to compare their biological properties. The genetically engineered mice previously developed with mouse mammary tumor virus (MMTV) promoter driven expression of activated ErbB2/Neu and recombinant Cre (FVB/N-MMTV-NIC) were interbred with Flox-PTEN mice; and FVB/N-ErbB2KI mice, harboring endogenous promoter driven activated ErbB2/Neu expression, FVB/N-MMTV-Cre mice and the flox-PTEN mice were interbred. Neu, Cre and PTEN genes were amplified by PCR for genotyping of the offsprings. ErbB2/Neu and PTEN expression in mammary tumors were detected by immunohistochemistry. Tumor formation time, tumor number, histopathology and lung metastasis were compared between two models, Ki-67 expression was detected by immunohistochemistry, and TUNEL staining of tumor tissues was performed. Two genetically engineered mouse models of ErbB2/Neu positive-PTEN homozygous deficient breast cancer were generated. The models were confirmed by genotyping and immunohistochemistry. One model with exogenous MMTV promoter driven expression of activated ErbB2/Neu and Cre coupling PTEN disruption was designated as NIC/PTEN(-/-) mice, and the other with MMTV-Cre induced endogenous promoter driven expression of activated ErbB2/Neu with PTEN disruption was designated as ErbB2KI/PTEN(-/-) mice. The tumor formation time in NIC/PTEN(-/-) mice was significantly shorter than that of ErbB2KI/PTEN(-/-) mice (30 vs 368 d, P<0.01); the number of tumor and incidence of lung metastasis was also significantly higher in NIC/PTEN(-/-) mice (10 vs 1-2 and 75.0% vs 37.5%, respectively, Ps<0.01). The Two models displayed distinct histopathological morphology. NIC/PTEN(-/-) tumor showed more Ki-67 positive cells than ErbB2KI/PTEN(-/-) tumor did (86.9%±2.8% vs 37.4%±7.2%, P<0.01), while the amount of cell apoptosis in tumors was not significantly different between two models. Two genetically engineered mouse

Alternative HER/PTEN/Akt Pathway Activation in HPV Positive and Negative Penile Carcinomas

PubMed Central

Stankiewicz, Elzbieta; Prowse, David M.; Ng, Mansum; Cuzick, Jack; Mesher, David; Hiscock, Frances; Lu, Yong-Jie; Watkin, Nicholas; Corbishley, Catherine; Lam, Wayne; Berney, Daniel M.

2011-01-01

Background The pathogenesis of penile squamous cell carcinoma (PSCC) is not well understood, though risk factors include human papillomavirus (HPV). Disruption of HER/PTEN/Akt pathway is present in many cancers; however there is little information on its function in PSCC. We investigated HER family receptors and phosphatase and tension homolog (PTEN) in HPV-positive and negative PSCC and its impact on Akt activation using immunohistochemistry and fluorescent in situ hybridisation (FISH). Methodology/Principal Findings 148 PSCCs were microarrayed and immunostained for phosphorylated EGFR (pEGFR), HER2, HER3, HER4, phosphorylated Akt (pAkt), Akt1 and PTEN proteins. EGFR and PTEN gene status were also evaluated using FISH. HPV presence was assessed by PCR. pEGFR expression was detected significantly less frequently in HPV-positive than HPV-negative tumours (p = 0.0143). Conversely, HER3 expression was significantly more common in HPV-positive cases (p = 0.0128). HER4, pAkt, Akt and PTEN protein expression were not related to HPV. HER3 (p = 0.0054) and HER4 (p = 0.0002) receptors significantly correlated with cytoplasmic Akt1 immunostaining. All three proteins positively correlated with tumour grade (HER3, p = 0.0029; HER4, p = 0.0118; Akt1, p = 0.0001). pEGFR expression correlated with pAkt but not with tumour grade or stage. There was no EGFR gene amplification. HER2 was not detected. PTEN protein expression was reduced or absent in 62% of tumours but PTEN gene copy loss was present only in 4% of PSCCs. Conclusions/Significance EGFR, HER3 and HER4 but not HER2 are associated with penile carcinogenesis. HPV-negative tumours tend to express significantly more pEGFR than HPV-positive cancers and this expression correlates with pAkt protein, indicating EGFR as an upstream regulator of Akt signalling in PSCC. Conversely, HER3 expression is significantly more common in HPV-positive cases and positively correlates with cytoplasmic Akt1 expression

Alternative HER/PTEN/Akt pathway activation in HPV positive and negative penile carcinomas.

PubMed

Stankiewicz, Elzbieta; Prowse, David M; Ng, Mansum; Cuzick, Jack; Mesher, David; Hiscock, Frances; Lu, Yong-Jie; Watkin, Nicholas; Corbishley, Catherine; Lam, Wayne; Berney, Daniel M

2011-03-02

The pathogenesis of penile squamous cell carcinoma (PSCC) is not well understood, though risk factors include human papillomavirus (HPV). Disruption of HER/PTEN/Akt pathway is present in many cancers; however there is little information on its function in PSCC. We investigated HER family receptors and phosphatase and tension homolog (PTEN) in HPV-positive and negative PSCC and its impact on Akt activation using immunohistochemistry and fluorescent in situ hybridisation (FISH). 148 PSCCs were microarrayed and immunostained for phosphorylated EGFR (pEGFR), HER2, HER3, HER4, phosphorylated Akt (pAkt), Akt1 and PTEN proteins. EGFR and PTEN gene status were also evaluated using FISH. HPV presence was assessed by PCR. pEGFR expression was detected significantly less frequently in HPV-positive than HPV-negative tumours (p = 0.0143). Conversely, HER3 expression was significantly more common in HPV-positive cases (p = 0.0128). HER4, pAkt, Akt and PTEN protein expression were not related to HPV. HER3 (p = 0.0054) and HER4 (p = 0.0002) receptors significantly correlated with cytoplasmic Akt1 immunostaining. All three proteins positively correlated with tumour grade (HER3, p = 0.0029; HER4, p = 0.0118; Akt1, p = 0.0001). pEGFR expression correlated with pAkt but not with tumour grade or stage. There was no EGFR gene amplification. HER2 was not detected. PTEN protein expression was reduced or absent in 62% of tumours but PTEN gene copy loss was present only in 4% of PSCCs. EGFR, HER3 and HER4 but not HER2 are associated with penile carcinogenesis. HPV-negative tumours tend to express significantly more pEGFR than HPV-positive cancers and this expression correlates with pAkt protein, indicating EGFR as an upstream regulator of Akt signalling in PSCC. Conversely, HER3 expression is significantly more common in HPV-positive cases and positively correlates with cytoplasmic Akt1 expression. HER4 and PTEN protein expression are not related to HPV infection

miR-367 promotes proliferation and invasion of hepatocellular carcinoma cells by negatively regulating PTEN

DOE Office of Scientific and Technical Information (OSTI.GOV)

Meng, Xiangrui, E-mail: mengxiangruibb2008@163.com; Lu, Peng; Fan, Qingxia

2016-01-29

MicroRNAs play important roles in the carcinogenesis of many types of cancers by inhibiting gene expression at posttranscriptional level. However, the roles of microRNAs in hepatocellular carcinoma, are still unclear. Here, we identified that miR-367 promotes hepatocellular carcinoma (HCC) cell proliferation by negatively regulates its target gene PTEN. The expression of miR-367 and PTEN are significantly inverse correlated in 35 HCC patients. In HCC cell line, CCK-8 proliferation assay indicated that the cell proliferation was promoted by miR-367, while miR-367 inhibitor significantly inhibited the cell proliferation. Transwell assay showed that miR-367 mimics significantly promoted the migration and invasion of HCCmore » cells, whereas miR-367 inhibitors significantly reduced cell migration and invasion. Luciferase assays confirmed that miR-367 directly bound to the 3'untranslated region of PTEN, and western blotting showed that miR-367 suppressed the expression of PTEN at the protein levels. This study indicated that miR-367 negatively regulates PTEN and promotes proliferation and invasion of HCC cells. Thus, miR-367 may represent a potential therapeutic target for HCC intervention. - Highlights: • miR-367 mimics promote the proliferation and invasion of HCC cells. • miR-367 inhibitors inhibit the proliferation and invasion of HCC cells. • miR-367 targets 3′UTR of PTEN in HCC cells. • miR-367 negatively regulates PTEN in HCC cells.« less

Targeting human apurinic/apyrimidinic endonuclease 1 (APE1) in phosphatase and tensin homolog (PTEN) deficient melanoma cells for personalized therapy.

PubMed

Abbotts, Rachel; Jewell, Rosalyn; Nsengimana, Jérémie; Maloney, David J; Simeonov, Anton; Seedhouse, Claire; Elliott, Faye; Laye, Jon; Walker, Christy; Jadhav, Ajit; Grabowska, Anna; Ball, Graham; Patel, Poulam M; Newton-Bishop, Julia; Wilson, David M; Madhusudan, Srinivasan

2014-05-30

Phosphatase and tensin homolog (PTEN) loss is associated with genomic instability. APE1 is a key player in DNA base excision repair (BER) and an emerging drug target in cancer. We have developed small molecule inhibitors against APE1 repair nuclease activity. In the current study we explored a synthetic lethal relationship between PTEN and APE1 in melanoma. Clinicopathological significance of PTEN mRNA and APE1 mRNA expression was investigated in 191 human melanomas. Preclinically, PTEN-deficient BRAF-mutated (UACC62, HT144, and SKMel28), PTEN-proficient BRAF-wildtype (MeWo), and doxycycline-inducible PTEN-knockout BRAF-wildtype MeWo melanoma cells were DNA repair expression profiled and investigated for synthetic lethality using a panel of four prototypical APE1 inhibitors. In human tumours, low PTEN mRNA and high APE1 mRNA was significantly associated with reduced relapse free and overall survival. Pre-clinically, compared to PTEN-proficient cells, PTEN-deficient cells displayed impaired expression of genes involved in DNA double strand break (DSB) repair. Synthetic lethality in PTEN-deficient cells was evidenced by increased sensitivity, accumulation of DSBs and induction of apoptosis following treatment with APE1 inhibitors. We conclude that PTEN deficiency is not only a promising biomarker in melanoma, but can also be targeted by a synthetic lethality strategy using inhibitors of BER, such as those targeting APE1.

MiR-21/PTEN Axis Promotes Skin Wound Healing by Dendritic Cells Enhancement.

PubMed

Han, Zhaofeng; Chen, Ya; Zhang, Yile; Wei, Aizhou; Zhou, Jian; Li, Qian; Guo, Lili

2017-10-01

A number of miRNAs associated with wound repair have been identified and characterized, but the mechanism has not been fully clarified. MiR-21 is one of wound-related lncRNAs, and the study aimed to explore the functional involvement of miR-21 and its concrete mechanism in wound healing. In this study, the rat model of skin wounds was established. The expression of miR-21, PTEN and related molecules of wound tissues or cells was determined by quantitative real-time PCR and Western blot, respectively. The regulatory role of miR-21 on PTEN was examined by luciferase reporter gene assay. Flow cytometry assay was applied to measure cell number changes. MiR-21 was upregulated at 6, 24, 48, 72 h after model establishment, and the increase reached a maximum at 24 h in wound tissues. MMP-9 expression presented the same tread as miR-21 and was significantly enhanced within 6 h of wound formation, and then remained to be increased to the maximum at 24 h. The increase of miR-21 was accompanied by the increase of cell total number and DCs ratio in wound fluids. MiR-21 overexpression significantly improved the healing of skin wounds and increased the ratio of DCs in rats. The results of using FL confirmed that miR-21 overexpression obviously promoted DCs differentiation. Additionally, miR-21 could activate AKT/PI3K signaling pathway via inhibition of PTEN. MiR-21 contributes to wound healing via inhibition of PTEN that activated AKT/PI3K signaling pathway to increase DCs. J. Cell. Biochem. 118: 3511-3519, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Kinetics of PTEN-mediated PI(3,4,5)P3 hydrolysis on solid supported membranes

PubMed Central

Liu, Chun; Deb, Sanghamitra; Ferreira, Vinicius S.; Xu, Eric; Baumgart, Tobias

2018-01-01

Phosphatidylinositides play important roles in cellular signaling and migration. Phosphatidylinositol-3,4,5-trisphosphate (PI(3,4,5)P3) is an important phosphatidylinositide because it acts as a secondary messenger to trigger cell movement and proliferation. A high level of PI(3,4,5)P3 at the plasma membrane is known to contribute to tumorigenesis. One key enzyme that regulates PI(3,4,5)P3 levels at the plasma membrane is phosphatase and tensin homologue deleted on chromosome 10 (PTEN), which dephosphorylates PI(3,4,5)P3 through hydrolysis to form phosphatidylinositol-4,5-bisphosphate (PI(4,5)P2). It has been reported that PI(4,5)P2 is involved in positive feedback in the PI(3,4,5)P3 hydrolysis by PTEN. However, how PI(3,4,5)P3 dephosphorylation by PTEN is regulated, is still under debate. How other PI(3,4,5)P3-binding proteins affect the dephosphorylation kinetics catalyzed by PTEN also remains unclear. Here, we develop a fluorescent-protein biosensor approach to study how PI(3,4,5)P3 dephosphorylation is regulated by PTEN as well as its membrane-mediated feedback mechanisms. Our observation of sigmoidal kinetics of the PI(3,4,5)P3 hydrolysis reaction supports the notion of autocatalysis in PTEN function. We developed a kinetic model to describe the observed reaction kinetics, which allowed us to i) distinguish between membrane-recruitment and allosteric activation of PTEN by PI(4,5)P2, ii) account for the influence of the biosensor on the observed reaction kinetics, and iii) demonstrate that all of these mechanisms contribute to the kinetics of PTEN-mediated catalysis. PMID:29447222

Kinetics of PTEN-mediated PI(3,4,5)P3 hydrolysis on solid supported membranes.

PubMed

Liu, Chun; Deb, Sanghamitra; Ferreira, Vinicius S; Xu, Eric; Baumgart, Tobias

2018-01-01

Phosphatidylinositides play important roles in cellular signaling and migration. Phosphatidylinositol-3,4,5-trisphosphate (PI(3,4,5)P3) is an important phosphatidylinositide because it acts as a secondary messenger to trigger cell movement and proliferation. A high level of PI(3,4,5)P3 at the plasma membrane is known to contribute to tumorigenesis. One key enzyme that regulates PI(3,4,5)P3 levels at the plasma membrane is phosphatase and tensin homologue deleted on chromosome 10 (PTEN), which dephosphorylates PI(3,4,5)P3 through hydrolysis to form phosphatidylinositol-4,5-bisphosphate (PI(4,5)P2). It has been reported that PI(4,5)P2 is involved in positive feedback in the PI(3,4,5)P3 hydrolysis by PTEN. However, how PI(3,4,5)P3 dephosphorylation by PTEN is regulated, is still under debate. How other PI(3,4,5)P3-binding proteins affect the dephosphorylation kinetics catalyzed by PTEN also remains unclear. Here, we develop a fluorescent-protein biosensor approach to study how PI(3,4,5)P3 dephosphorylation is regulated by PTEN as well as its membrane-mediated feedback mechanisms. Our observation of sigmoidal kinetics of the PI(3,4,5)P3 hydrolysis reaction supports the notion of autocatalysis in PTEN function. We developed a kinetic model to describe the observed reaction kinetics, which allowed us to i) distinguish between membrane-recruitment and allosteric activation of PTEN by PI(4,5)P2, ii) account for the influence of the biosensor on the observed reaction kinetics, and iii) demonstrate that all of these mechanisms contribute to the kinetics of PTEN-mediated catalysis.

11β-HSD1 Modulates LPS-Induced Innate Immune Responses in Adipocytes by Altering Expression of PTEN

PubMed Central

Lai, Wenfang; Tian, Xue; Xiang, Qing; Chu, Kedan; Wei, Yicong; Deng, Jingti; Zhang, Shaoping; Brown, John

2015-01-01

Inhibition of 11β-hydroxysteroid dehydrogenase type 1 (11β-HSD1) represents a therapeutic target for treating hyperglycemia in type 2 diabetes. Here, we investigate the effects of 11β-HSD1 on the innate immune response of adipocytes to produce proinflammatory cytokines. The 11β-HSD1 inhibitor emodin, or 11β-HSD1-targeted small interfering RNA, dose dependently suppressed IL-6, IL-1β, and TNF-α expression in lipopolysaccharide-treated 3T3-L1 adipocytes. Inhibiting 11β-HSD1 also reduced phosphatase and tensin homologue (PTEN) expression, a negative regulator of phosphatidylinositol 3-kinase effects, whereas 1pM cortisone or dexamethasone induced IL-6 and PTEN levels. PTEN-targeted small interfering RNA decreased IL-6, IL-1β, and TNF-α without affecting 11β-HSD1 levels. Correspondingly, emodin increased phosphorylated protein kinase B (p-PKB) (Ser473) to PKB ratio but not p-PKB (Thr308) to PKB ratio. Emodin did not increase the p-PKB (Ser473) to PKB ratio when the rapamycin-insensitive companion of mTOR was depleted, further supporting the involvement of mammalian target of rapamycin complex 2 in PKB phosphorylation. Moreover, emodin suppressed phosphorylated inhibitor of κB α (p-IκBα) to IκBα ratio and reduced nuclear factor κ B subunit p50 in the nuclear fraction. In contrast, 1pM cortisone or dexamethasone decreased p-PKB (Ser473) to PKB ratio, increased p-IκBα to IκBα ratio, and increased nuclear NF-κB subunit p50. Additionally, wortmannin had similar effects on IL-6, p-PKB (Ser473) to PKB ratio, and p-IκBα to IκBα ratio as 1pM cortisone or dexamethasone. Finally, emodin treatment of streptozotocin diabetic rats on a high-fat diet reduced levels of IL-6, PTEN, Cluster of Differentiation 68, and the ratio of p-IκBα to IκBα in visceral fat, indicating that our findings in vitro may also apply to visceral fat in vivo. Together, these results suggest that inhibiting 11β-HSD1 reduces lipopolysaccharide-induced proinflammatory innate

PTEN Loss Is Associated with Worse Outcome in HER2-Amplified Breast Cancer Patients but Is Not Associated with Trastuzumab Resistance.

PubMed

Stern, Howard M; Gardner, Humphrey; Burzykowski, Tomasz; Elatre, Wafaa; O'Brien, Carol; Lackner, Mark R; Pestano, Gary A; Santiago, Angela; Villalobos, Ivonne; Eiermann, Wolfgang; Pienkowski, Tadeusz; Martin, Miguel; Robert, Nicholas; Crown, John; Nuciforo, Paolo; Bee, Valerie; Mackey, John; Slamon, Dennis J; Press, Michael F

2015-05-01

To investigate the clinical relevance of PTEN in HER2-amplified and HER2-nonamplified disease. We assessed PTEN status in two large adjuvant breast cancer trials (BCIRG-006 and BCIRG-005) using a PTEN immunohistochemical (IHC) assay that was previously validated in a panel of 33 breast cancer cell lines and prostate cancer tissues with known PTEN gene deletion. In the HER2-positive patient population, absence of tumor cell PTEN staining occurred at a rate of 5.4% and was independent of ER/PR status. In contrast, 15.9% of HER2-negative patients exhibited absence of PTEN staining with the highest frequency seen in triple-negative breast cancer (TNBC) subgroup versus ER/PR-positive patients (35.1% vs. 10.9%). Complete absence of PTEN staining in tumor cells was associated with poor clinical outcome in HER2-positive disease. Those patients whose cancers demonstrated absent PTEN staining had a significant decrease in disease-free survival (DFS) and overall survival (OS) compared with patients with tumors exhibiting any PTEN staining patterns (low, moderate, or high). Trastuzumab appeared to provide clinical benefit even for patients lacking PTEN staining. In the HER2-negative population, there were no statistically significant differences in clinical outcome based on PTEN status. This study is the largest to date examining PTEN status in breast cancer and the data suggest that the rate and significance of PTEN status differ between HER2-positive and HER2-negative disease. Furthermore, the data clearly suggest that HER2-positive patients with PTEN loss still benefit from trastuzumab. ©2015 American Association for Cancer Research.

PTEN loss is associated with worse outcome in HER2-amplified breast cancer patients but is not associated with trastuzumab resistance

PubMed Central

Stern, Howard M.; Gardner, Humphrey; Burzykowski, Tomasz; Elatre, Wafaa; O’Brien, Carol; Lackner, Mark R.; Pestano, Gary A.; Santiago, Angela; Villalobos, Ivonne; Eiermann, Wolfgang; Pienkowski, Tadeusz; Martin, Miguel; Robert, Nicholas; Crown, John; Nuciforo, Paolo; Bee, Valerie; Mackey, John; Slamon, Dennis J.; Press, Michael F.

2015-01-01

Purpose To investigate the clinical relevance of PTEN in HER2-amplified and HER2-non-amplified disease. Experimental Design We assessed PTEN status in two large adjuvant breast cancer trials (BCIRG-006 and BCIRG-005) using a PTEN IHC assay that was previously validated in a panel of 33 breast cancer cell lines and prostate cancer tissues with known PTEN gene deletion. Results In the HER2-positive patient population, absence of tumor cell PTEN staining occurred at a rate of 5.4% and was independent of ER/PR status. In contrast, 15.9% of HER2-negative patients exhibited absence of PTEN staining with the highest frequency seen in triple negative breast cancer (TNBC) subgroup versus ER/PR-positive patients (35.1% vs. 10.9%). Complete absence of PTEN staining in tumor cells was associated with poor clinical outcome in HER2-positive disease. Those patients whose cancers demonstrated absent PTEN staining had a significant decrease in disease-free survival (DFS) and overall survival (OS) compared to patients with tumors exhibiting any PTEN staining patterns (low, moderate or high). Trastuzumab appeared to provide clinical benefit even for patients lacking PTEN staining. In the HER2-negative population there were no statistically significant differences in clinical outcome based on PTEN status. Conclusions This study is the largest to date examining PTEN status in breast cancer and the data suggest that the rate and significance of PTEN status differ between HER2-positive and HER2-negative disease. Furthermore, the data clearly suggest that HER2-positive patients with PTEN loss still benefit from trastuzumab. PMID:25649019

The PTEN protein: cellular localization and post-translational regulation.

PubMed

Leslie, Nick R; Kriplani, Nisha; Hermida, Miguel A; Alvarez-Garcia, Virginia; Wise, Helen M

2016-02-01

The phosphatase and tensin homologue deleted on chromosome 10 (PTEN) phosphatase dephosphorylates PIP3, the lipid product of the class I PI 3-kinases, and suppresses the growth and proliferation of many cell types. It has been heavily studied, in large part due to its status as a tumour suppressor, the loss of function of which is observed through diverse mechanisms in many tumour types. Here we present a concise review of our understanding of the PTEN protein and highlight recent advances, particularly in our understanding of its localization and regulation by ubiquitination and SUMOylation. © 2016 Authors; published by Portland Press Limited.

Ursolic acid activates the apoptosis of prostate cancer via ROCK/PTEN mediated mitochondrial translocation of cofilin-1

PubMed Central

Mu, Dawei; Zhou, Gaobiao; Li, Jianye; Su, Bin; Guo, Heqing

2018-01-01

Ursolic acid has various pharmacological activities, and can reduce blood fat as well as having antihepatic, antitumoral, anti-inflammatory and antiviral properties. However, the pro-apoptotic mechanism by which ursolic acid influences human prostate cancer requires additional study. The aim of the present study was to assess whether ursolic acid activates the apoptosis of prostate cancer and to investigate the mechanism by which the Rho-associated protein kinase 1 (ROCK1)/phosphatase and tensin homolog (PTEN) signaling pathway performs a role in ursolic acid-mediated cofilin-1 to induce apoptosis in human prostate cancer. Firstly, the present study determined the pro-apoptotic mechanism by which ursolic acid influences the cell proliferation and apoptosis of human prostate LNCaP cancer cells. Caspase-3/9 activities and ROCK1, PTEN, Cofilin-1 and cytochrome c protein expression levels were also analyzed. In the present study, it is reported that the pro-apoptotic mechanism of ursolic acid potently suppressed the cell proliferation of human prostate LNCaP cancer cells. The present study revealed that the mediation of ROCK1/PTEN-cofilin-1/cytochrome c protein expression activates caspase-3/9 activities which subsequently induced the apoptosis of human prostate cancer cells. In conclusion, these findings demonstrated that ursolic acid activates the apoptosis of prostate cancer via ROCK/PTEN mediated cofilin-1/cytochrome c which mediated caspase-3/9 activities. PMID:29435058

PTEN Loss Does Not Predict for Response to RAD001 (Everolimus) in a Glioblastoma Orthotopic Xenograft Test Panel

PubMed Central

Yang, Lin; Clarke, Michelle J.; Carlson, Brett L.; Mladek, Ann C.; Schroeder, Mark A.; Decker, Paul; Wu, Wenting; Kitange, Gaspar J.; Grogan, Patrick T.; Goble, Jennie M.; Uhm, Joon; Galanis, Evanthia; Giannini, Caterina; Lane, Heidi A.; James, C. David; Sarkaria, Jann N.

2014-01-01

Purpose Hyperactivation of the phosphatidylinositol 3-kinase/Akt signaling through disruption of PTEN function is common in glioblastoma multiforme, and these genetic changes are predicted to enhance sensitivity to mammalian target of rapamycin (mTOR) inhibitors such as RAD001 (everolimus). Experimental Design To test whether PTEN loss could be used as a predictive marker for mTOR inhibitor sensitivity, the response of 17 serially transplantable glioblastoma multiforme xenografts was evaluated in an orthotopic therapy evaluation model. Of these 17 xenograft lines, 7 have either genomic deletion or mutation of PTEN. Results Consistent with activation of Akt signaling, there was a good correlation between loss of PTEN function and elevated levels of Akt phosphorylation. However, of the 7 lines with disrupted PTEN function, only 1 tumor line (GBM10) was significantly sensitive to RAD001 therapy (25% prolongation in median survival), whereas1 of 10 xenograft lines with wild-type PTEN was significantly sensitive to RAD001 (GS22; 34% prolongation in survival). Relative to placebo, 5 days of RAD001 treatment was associated with a marked 66% reduction in the MIB1 proliferation index in the sensitive GBM10 line (deleted PTEN) compared with a 25% and 7% reduction in MIB1 labeling index in the insensitive GBM14 (mutant PTEN) and GBM15 (wild-type PTEN) lines, respectively. Consistent with a cytostatic antitumor effect, bioluminescent imaging of luciferase-transduced intracranial GBM10 xenografts showed slowed tumor growth without significant tumor regression during RAD001 therapy. Conclusion These data suggest that loss of PTEN function is insufficient to adequately predict responsiveness to mTOR inhibitors in glioblastoma multiforme. PMID:18559622

Dysregulation of synaptic plasticity precedes appearance of morphological defects in a Pten conditional knockout mouse model of autism.

PubMed

Takeuchi, Koichi; Gertner, Michael J; Zhou, Jing; Parada, Luis F; Bennett, Michael V L; Zukin, R Suzanne

2013-03-19

The phosphoinositide signaling system is a crucial regulator of neural development, cell survival, and plasticity. Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) negatively regulates phosphatidylinositol 3-kinase signaling and downstream targets. Nse-Cre Pten conditional knockout mice, in which Pten is ablated in granule cells of the dentate gyrus and pyramidal neurons of the hippocampal CA3, but not CA1, recapitulate many of the symptoms of humans with inactivating PTEN mutations, including progressive hypertrophy of the dentate gyrus and deficits in hippocampus-based social and cognitive behaviors. However, the impact of Pten loss on activity-dependent synaptic plasticity in this clinically relevant mouse model of Pten inactivation remains unclear. Here, we show that two phosphatidylinositol 3-kinase- and protein synthesis-dependent forms of synaptic plasticity, theta burst-induced long-term potentiation and metabotropic glutamate receptor (mGluR)-dependent long-term depression, are dysregulated at medial perforant path-to-dentate gyrus synapses of young Nse-Cre Pten conditional knockout mice before the onset of visible morphological abnormalities. In contrast, long-term potentiation and mGluR-dependent long-term depression are normal at CA3-CA1 pyramidal cell synapses at this age. Our results reveal that deletion of Pten in dentate granule cells dysregulates synaptic plasticity, a defect that may underlie abnormal social and cognitive behaviors observed in humans with Pten inactivating mutations and potentially other autism spectrum disorders.

Cystic Fibrosis Transmembrane Conductance Regulator Attaches Tumor Suppressor PTEN to the Membrane and Promotes Anti Pseudomonas aeruginosa Immunity.

PubMed

Riquelme, Sebastián A; Hopkins, Benjamin D; Wolfe, Andrew L; DiMango, Emily; Kitur, Kipyegon; Parsons, Ramon; Prince, Alice

2017-12-19

The tumor suppressor PTEN controls cell proliferation by regulating phosphatidylinositol-3-kinase (PI3K) activity, but the participation of PTEN in host defense against bacterial infection is less well understood. Anti-inflammatory PI3K-Akt signaling is suppressed in patients with cystic fibrosis (CF), a disease characterized by hyper-inflammatory responses to airway infection. We found that Ptenl -/- mice, which lack the NH 2 -amino terminal splice variant of PTEN, were unable to eradicate Pseudomonas aeruginosa from the airways and could not generate sufficient anti-inflammatory PI3K activity, similar to what is observed in CF. PTEN and the CF transmembrane conductance regulator (CFTR) interacted directly and this interaction was necessary to position PTEN at the membrane. CF patients under corrector-potentiator therapy, which enhances CFTR transport to the membrane, have increased PTEN amounts. These findings suggest that improved CFTR trafficking could enhance P. aeruginosa clearance from the CF airway by activating PTEN-mediated anti-bacterial responses and might represent a therapeutic strategy. Published by Elsevier Inc.

In vivo identification of tumor suppressive PTEN ceRNAs in an oncogenic BRAF-induced mouse model of melanoma

PubMed Central

Karreth, Florian A.; Tay, Yvonne; Perna, Daniele; Ala, Ugo; Tan, Shen Mynn; Rust, Alistair G.; DeNicola, Gina; Webster, Kaitlyn A.; Weiss, Dror; Perez-Mancera, Pedro A.; Krauthammer, Michael; Halaban, Ruth; Provero, Paolo; Adams, David J.; Tuveson, David A.; Pandolfi, Pier Paolo

2011-01-01

Summary We recently proposed that competitive endogenous RNAs (ceRNAs) sequester microRNAs to regulate mRNA transcripts containing common microRNA recognition elements (MREs). However, the functional role of ceRNAs in cancer remains unknown. Loss of PTEN, a tumor suppressor regulated by ceRNA activity, frequently occurs in melanoma. Here, we report the discovery of significant enrichment of putative PTEN ceRNAs among genes whose loss accelerates tumorigenesis following Sleeping Beauty insertional mutagenesis in a mouse model of melanoma. We validated several putative PTEN ceRNAs and further characterized one, the ZEB2 transcript. We show that ZEB2 modulates PTEN protein levels in a microRNA-dependent, protein coding-independent manner. Attenuation of ZEB2 expression activates the PI3K/AKT pathway, enhances cell transformation, and commonly occurs in human melanomas and other cancers expressing low PTEN levels. Our study genetically identifies multiple putative microRNA decoys for PTEN, validates ZEB2 mRNA as a bona fide PTEN ceRNA, and demonstrates that abrogated ZEB2 expression cooperates with BRAFV600E to promote melanomagenesis. PMID:22000016

A recessive form of extreme macrocephaly and mild intellectual disability complements the spectrum of PTEN hamartoma tumour syndrome.

PubMed

Schwerd, Tobias; Khaled, Andrea V; Schürmann, Manfred; Chen, Hannah; Händel, Norman; Reis, André; Gillessen-Kaesbach, Gabriele; Uhlig, Holm H; Abou Jamra, Rami

2016-06-01

PTEN hamartoma tumour syndrome (PHTS) is caused by heterozygous variants in PTEN and is characterised by tumour predisposition, macrocephaly, and cognition impairment. Bi-allelic loss of PTEN activity has not been reported so far and animal models suggest that bi-allelic loss of PTEN activity is embryonically lethal. Here, we report the identification of a novel homozygous variant in PTEN, NM_000314.4; c.545T>C; p.Leu182Ser, in two adolescent siblings with severe macrocephaly and mild intellectual disability. The variant is predicted to be damaging and is associated with significantly increased phospho-S6 downstream of PTEN. The absence of tumours in the two homozygous siblings as well as lack of symptoms of PHTS in the heterozygous carriers of the family suggest that this particular variant is functionally hypomorphic rather than deleterious.

A recessive form of extreme macrocephaly and mild intellectual disability complements the spectrum of PTEN hamartoma tumour syndrome

PubMed Central

Schwerd, Tobias; Khaled, Andrea V; Schürmann, Manfred; Chen, Hannah; Händel, Norman; Reis, André; Gillessen-Kaesbach, Gabriele; Uhlig, Holm H; Abou Jamra, Rami

2016-01-01

PTEN hamartoma tumour syndrome (PHTS) is caused by heterozygous variants in PTEN and is characterised by tumour predisposition, macrocephaly, and cognition impairment. Bi-allelic loss of PTEN activity has not been reported so far and animal models suggest that bi-allelic loss of PTEN activity is embryonically lethal. Here, we report the identification of a novel homozygous variant in PTEN, NM_000314.4; c.545T>C; p.Leu182Ser, in two adolescent siblings with severe macrocephaly and mild intellectual disability. The variant is predicted to be damaging and is associated with significantly increased phospho-S6 downstream of PTEN. The absence of tumours in the two homozygous siblings as well as lack of symptoms of PHTS in the heterozygous carriers of the family suggest that this particular variant is functionally hypomorphic rather than deleterious. PMID:26443266

The microbiome in PTEN hamartoma tumor syndrome.

PubMed

Byrd, Victoria; Getz, Ted; Padmanabhan, Roshan; Arora, Hans; Eng, Charis

2018-03-01

Germline PTEN mutations defining PTEN hamartoma tumor syndrome (PHTS) confer heritable predisposition to breast, endometrial, thyroid and other cancers with known age-related risks, but it remains impossible to predict if any individual will develop cancer. In the general population, gut microbial dysbiosis has been linked to cancer, yet is unclear whether these are associated in PHTS patients. In this pilot study, we aimed to characterize microbial composition of stool, urine, and oral wash from 32 PTEN mutation-positive individuals using 16S rRNA gene sequencing. PCoA revealed clustering of the fecal microbiome by cancer history ( P  = 0.03, R 2  = 0.04). Fecal samples from PHTS cancer patients had relatively more abundant operational taxonomic units (OTUs) from family Rikenellaceae and unclassified members of Clostridia compared to those from non-cancer patients, whereas families Peptostreptococcaceae, Enterobacteriaceae, and Bifidobacteriaceae represented relatively more abundant OTUs among fecal samples from PHTS non-cancer patients. Functional metagenomic prediction revealed enrichment of the folate biosynthesis, genetic information processing and cell growth and death pathways among fecal samples from PHTS cancer patients compared to non-cancer patients. We found no major shifts in overall diversity and no clustering by cancer history among oral wash or urine samples. Our observations suggest the utility of an expanded study to interrogate gut dysbiosis as a potential cancer risk modifier in PHTS patients. © 2018 The authors.

Structure of the PTEN-like region of auxilin, a detector of clathrin-coated vesicle budding

PubMed Central

Guan, Rong; Han, Dai; Harrison, Stephen C.; Kirchhausen, Tomas

2010-01-01

Auxilin, a J-domain containing protein, recruits the Hsc70 uncoating ATPase to newly budded clathrin-coated vesicles. The timing of auxilin arrival determines that uncoating will commence only after the clathrin lattice has fully assembled and after membrane fission is complete. Auxilin has a region resembling PTEN, a PI3P phosphatase. We have determined the crystal structure of this region of bovine auxilin 1; it indeed resembles PTEN closely. A change in the structure of the P-loop accounts for the lack of phosphatase activity. Inclusion of phosphatidylinositol phosphates substantially enhances liposome binding by wild-type auxilin, but not by various mutants bearing changes in loops of the C2 domain. Nearly all these mutations also prevent recruitment of auxilin to newly budded coated vesicles. We propose a specific geometry for auxilin association with a membrane bilayer and discuss implications of this model for the mechanism by which auxilin detects separation of a vesicle from its parent membrane. PMID:20826345

PTEN IDENTIFIED AS IMPORTANT RISK FACTOR OF CHRONIC OBSTRUCTIVE PULMONARY DISEASE

PubMed Central

Hosgood, H Dean; Menashe, Idan; He, Xingzhou; Chanock, Stephen; Lan, Qing

2009-01-01

Common genetic variation may play an important role in altering chronic obstructive pulmonary disease (COPD) risk. In Xuanwei, China, the COPD rate is more than twice the Chinese national average, and COPD is strongly associated with in-home coal use. To identify genetic variation that may be associated with COPD in a population with substantial in-home coal smoke exposures, we evaluated 1,261 single nucleotide polymorphisms (SNPs) in 380 candidate genes potentially relevant for cancer and other human diseases in a population-based case-control study in Xuanwei (53 cases; 107 controls). PTEN was the most significantly associated gene with COPD in a minP analysis using 20,000 permutations (P = 0.00005). SNP-based analyses found that homozygote variant carriers of PTEN rs701848 (ORTT = 0.12, 95%CI = 0.03 - 0.47) had a significant decreased risk of COPD. PTEN, or phosphatase and tensin homolog, is an important regulator of cell cycle progression and cellular survival via the AKT signaling pathway. Our exploratory analysis suggests that genetic variation in PTEN may be an important risk factor of COPD in Xuanwei. However, due to the small sample size, additional studies are needed to evaluate these associations within Xuanwei and other populations with coal smoke exposures. PMID:19625176

Suppression of Prostate Tumors by INK4C and PTEN

DTIC Science & Technology

2007-12-01

or Pten/ single mutant mice developed tumors in both lobes (Fig. 2). Pheochromocytomas developed in the adrenals of 84% of p18/ Pten/ mice...0 1 (13) 14 (74) Adrenal Normal 14 6 8 3 5 4 4 3 1 Medullary hyperplasia 1 0 4 4 2 2 1 1 2 Pheochromocytoma 0 0 2 (14)e 2 (22) 13 (65)f 2 (25) 12 (71...Hematoxylin and eosin staining of adrenal glands from different genotypes. Hyperplasia (H) and pheochromocytoma (T) of the adrenal medulla (AM

Prediction of functionally significant single nucleotide polymorphisms in PTEN tumor suppressor gene: An in silico approach.

PubMed

Khan, Imran; Ansari, Irfan A; Singh, Pratichi; Dass J, Febin Prabhu

2017-09-01

The phosphatase and tensin homolog (PTEN) gene plays a crucial role in signal transduction by negatively regulating the PI3K signaling pathway. It is the most frequent mutated gene in many human-related cancers. Considering its critical role, a functional analysis of missense mutations of PTEN gene was undertaken in this study. Thirty five nonsynonymous single nucleotide polymorphisms (nsSNPs) within the coding region of the PTEN gene were selected for our in silico investigation, and five nsSNPs (G129E, C124R, D252G, H61D, and R130G) were found to be deleterious based on combinatorial predictions of different computational tools. Moreover, molecular dynamics (MD) simulation was performed to investigate the conformational variation between native and all the five mutant PTEN proteins having predicted deleterious nsSNPs. The results of MD simulation of all mutant models illustrated variation in structural attributes such as root-mean-square deviation, root-mean-square fluctuation, radius of gyration, and total energy; which depicts the structural stability of PTEN protein. Furthermore, mutant PTEN protein structures also showed a significant variation in the solvent accessible surface area and hydrogen bond frequencies from the native PTEN structure. In conclusion, results of this study have established the deleterious effect of the all the five predicted nsSNPs on the PTEN protein structure. Thus, results of the current study can pave a new platform to sort out nsSNPs that can be undertaken for the confirmation of their phenotype and their correlation with diseased status in case of control studies. © 2016 International Union of Biochemistry and Molecular Biology, Inc.

The RhoA-ROCK-PTEN pathway as a molecular switch for anchorage dependent cell behavior.

PubMed

Yang, Seungwon; Kim, Hyun-Man

2012-04-01

The proliferation of anchorage-dependent cells of mesenchymal origin requires the attachment of the cells to substrates. Thus, cells that are poorly attached to substrates exhibit retarded cell cycle progression or apoptotic death. A major disadvantage of most polymers used in tissue engineering is their hydrophobicity; hydrophobic surfaces do not allow cells to attach firmly and, therefore, do not allow normal proliferation rates. In this study, we investigated the molecular mechanism underlying the reduced proliferation rate of cells that are poorly attached to substrates. There was an inverse relationship between the activity of the small GTPase RhoA (RhoA) and the cell proliferation rate. RhoA activity correlated inversely with the strength of cell adhesion to the substrates. The high RhoA activity in the cells poorly attached to substrates caused an increase in the activity of Rho-associated kinase (ROCK), a well-known effector of RhoA that upregulated the activity of phosphatase and tensin homolog (PTEN). The resulting activated PTEN downregulated Akt activity, which is essential for cell proliferation. Thus, the cells that were poorly attached to substrates showed low levels of cell proliferation because the RhoA-ROCK-PTEN pathway was hyperactive. In addition, RhoA activity seemed to be related to focal adhesion kinase (FAK) activity. Weak FAK activity in these poorly attached cells failed to downregulate the high RhoA activity that restrained cell proliferation. Interestingly, reducing the expression of any component of the RhoA-ROCK-PTEN pathway rescued the proliferation rate without physico-chemical surface modifications. Based on these results, we suggest that the RhoA-ROCK-PTEN pathway acts as a molecular switch to control cell proliferation and determine anchorage dependence. In cells that are poorly attached to substrates, its inhibition is sufficient to restore cell proliferation without the need for physico-chemical modification of the material

Exploring the Hypersensitivity of PTEN Deleted Prostate Cancer Stem Cells to WEE1 Tyrosine Kinase Inhibitors

DTIC Science & Technology

2015-12-01

xenograft tumors. The results from these studies will reveal whether targeting PTEN-deficient human tumors with WEE1 inhibitors can induce specific... xenograft tumors formed by PTEN- PSAlo PCSCs in castrated male immunocompromised mice. What was accomplished under these goals? Aim 1. Examine...prostate cancer stem cells. Aim 3. Investigate the cytotoxicity of WEE1 inhibitors against recalcitrant xenograft tumors formed by PTEN- CSCs in

Detecting Germline PTEN Mutations Among At-Risk Patients With Cancer: An Age- and Sex-Specific Cost-Effectiveness Analysis.

PubMed

Ngeow, Joanne; Liu, Chang; Zhou, Ke; Frick, Kevin D; Matchar, David B; Eng, Charis

2015-08-10

Cowden syndrome (CS) is an autosomal dominant disorder characterized by benign and malignant tumors. One-quarter of patients who are diagnosed with CS have pathogenic germline PTEN mutations, which increase the risk of the development of breast, thyroid, uterine, renal, and other cancers. PTEN testing and regular, intensive cancer surveillance allow for early detection and treatment of these cancers for mutation-positive patients and their relatives. Individual CS-related features, however, occur commonly in the general population, making it challenging for clinicians to identify CS-like patients to offer PTEN testing. We calculated the cost per mutation detected and analyzed the cost-effectiveness of performing selected PTEN testing among CS-like patients using a semi-quantitative score (the PTEN Cleveland Clinic [CC] score) compared with existing diagnostic criteria. In our model, first-degree relatives of the patients with detected PTEN mutations are offered PTEN testing. All individuals with detected PTEN mutations are offered cancer surveillance. CC score at a threshold of 15 (CC15) costs from $3,720 to $4,573 to detect one PTEN mutation, which is the most inexpensive among the different strategies. At base-case, CC10 is the most cost-effective strategy for female patients who are younger than 40 years, and CC15 is the most cost-effective strategy for female patients who are between 40 and 60 years of age and male patients of all ages. In sensitivity analyses, CC15 is robustly the most cost-effective strategy for probands who are younger than 60 years. Use of the CC score as a clinical risk calculator is a cost-effective prescreening method to identify CS-like patients for PTEN germline testing. © 2015 by American Society of Clinical Oncology.

Difluorinated-curcumin (CDF) restores PTEN expression in colon cancer cells by down-regulating miR-21.

PubMed

Roy, Sanchita; Yu, Yingjie; Padhye, Subhash B; Sarkar, Fazlul H; Majumdar, Adhip P N

2013-01-01

Despite recent advancement in medicine, nearly 50% of patients with colorectal cancer show recurrence of the disease. Although the reasons for the high relapse are not fully understood, the presence of chemo- and radiotherapy-resistant cancer stem/stem-like cells, where many oncomirs like microRNA-21 (miR-21) are upregulated, could be one of the underlying causes. miR-21 regulates the processes of invasion and metastasis by downregulating multiple tumor/metastatic suppressor genes including PTEN (phosphatase and tensin homolog). Tumor suppressor protein PTEN controls self-renewal of stem cells. Indeed, our current data demonstrate a marked downregulation of PTEN in SCID mice xenografts of miR-21 over-expressing colon cancer HCT116 cells. Colonospheres that are highly enriched in cancer stem/stem like cells reveal increased miR-21 expression and decreased PTEN. Difluorinated curcumin (CDF), a novel analog of the dietary ingredient curcumin, which has been shown to inhibit the growth of 5-Flurouracil + Oxaliplatin resistant colon cancer cells, downregulated miR-21 in chemo-resistant colon cancer HCT116 and HT-29 cells and restored PTEN levels with subsequent reduction in Akt phosphorylation. Similar results were also observed in metastatic colon cancer SW620 cells. Since PTEN-Akt confers drug resistance to different malignancies including colorectal cancer, our observation of normalization of miR-21-PTEN-Akt pathway by CDF suggests that the compound could be a potential therapeutic agent for chemotherapy-resistant colorectal cancer.

Glioma cell VEGFR-2 confers resistance to chemotherapeutic and antiangiogenic treatments in PTEN-deficient glioblastoma

PubMed Central

Blaes, Jonas; Osswald, Matthias; Rübmann, Petra; Milford, David; Urban, Severino; Jestaedt, Leonie; Heiland, Sabine; Bendszus, Martin; Hertenstein, Anne; Pfenning, Philipp-Niclas; de Almodóvar, Carmen Ruiz; Wick, Antje; Winkler, Frank; von Deimling, Andreas; Platten, Michael; Wick, Wolfgang; Weiler, Markus

2015-01-01

Loss of the tumor suppressor phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is a prerequisite for tumor cell-specific expression of vascular endothelial growth factor receptor (VEGFR)-2 in glioblastoma defining a subgroup prone to develop evasive resistance towards antiangiogenic treatments. Immunohistochemical analysis of human tumor tissues showed VEGFR-2 expression in glioma cells in 19% of specimens examined, mainly in the infiltration zone. Glioma cell VEGFR-2 positivity was restricted to PTEN-deficient tumor specimens. PTEN overexpression reduced VEGFR-2 expression in vitro, as well as knock-down of raptor or rictor. Genetic interference with VEGFR-2 revealed proproliferative, antiinvasive and chemoprotective functions for VEGFR-2 in glioma cells. VEGFR-2-dependent cellular effects were concomitant with activation of 'kappa-light-chain-enhancer’ of activated B-cells, protein kinase B, and N-myc downstream regulated gene 1. Two-photon in vivo microscopy revealed that expression of VEGFR-2 in glioma cells hampers antiangiogenesis. Bevacizumab induces a proinvasive response in VEGFR-2-positive glioma cells. Patients with PTEN-negative glioblastomas had a shorter survival after initiation of bevacizumab therapy compared with PTEN-positive glioblastomas. Conclusively, expression of VEGFR-2 in glioma cells indicates an aggressive glioblastoma subgroup developing early resistance to temozolomide or bevacizumab. Loss of PTEN may serve as a biomarker identifying those tumors upfront by routine neuropathological methods. PMID:25682871

PTEN Regulates PI(3,4)P2 Signaling Downstream of Class I PI3K.

PubMed

Malek, Mouhannad; Kielkowska, Anna; Chessa, Tamara; Anderson, Karen E; Barneda, David; Pir, Pınar; Nakanishi, Hiroki; Eguchi, Satoshi; Koizumi, Atsushi; Sasaki, Junko; Juvin, Véronique; Kiselev, Vladimir Y; Niewczas, Izabella; Gray, Alexander; Valayer, Alexandre; Spensberger, Dominik; Imbert, Marine; Felisbino, Sergio; Habuchi, Tomonori; Beinke, Soren; Cosulich, Sabina; Le Novère, Nicolas; Sasaki, Takehiko; Clark, Jonathan; Hawkins, Phillip T; Stephens, Len R

2017-11-02

The PI3K signaling pathway regulates cell growth and movement and is heavily mutated in cancer. Class I PI3Ks synthesize the lipid messenger PI(3,4,5)P 3 . PI(3,4,5)P 3 can be dephosphorylated by 3- or 5-phosphatases, the latter producing PI(3,4)P 2 . The PTEN tumor suppressor is thought to function primarily as a PI(3,4,5)P 3 3-phosphatase, limiting activation of this pathway. Here we show that PTEN also functions as a PI(3,4)P 2 3-phosphatase, both in vitro and in vivo. PTEN is a major PI(3,4)P 2 phosphatase in Mcf10a cytosol, and loss of PTEN and INPP4B, a known PI(3,4)P 2 4-phosphatase, leads to synergistic accumulation of PI(3,4)P 2 , which correlated with increased invadopodia in epidermal growth factor (EGF)-stimulated cells. PTEN deletion increased PI(3,4)P 2 levels in a mouse model of prostate cancer, and it inversely correlated with PI(3,4)P 2 levels across several EGF-stimulated prostate and breast cancer lines. These results point to a role for PI(3,4)P 2 in the phenotype caused by loss-of-function mutations or deletions in PTEN. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Effects of PTEN inhibition on the regulation of Tau phosphorylation in rat cortical neuronal injury after oxygen and glucose deprivation.

PubMed

Zhao, Jing; Chen, Yurong; Xu, Yuxia; Pi, Guanghuan

2016-01-01

This report investigated the involvement of the PTEN pathway in the regulation of Tau phosphorylation using an oxygen and glucose deprivation (OGD) model with rat cortical neurons. Primary cortical neurons were used to establish the oxygen and glucose deprivation (OGD) model in vitro. These were randomly divided into control, OGD, bpV+OGD, As+OGD, Se+OGD and Mock treatment groups. The neuron viability was assessed by MTT, the cell apoptosis was detected using TUNEL staining. The expression of Phospho-PTEN/PTEN, Phospho-Tau/Tau, Phospho-Akt/Akt and Phospho-GSK-3β/GSK-3β were detected by Western blotting. OGD induced Tau phosphorylation through PTEN and glycogen synthase kinase-3β (GSK-3β) activation, together with a decrease in AKT activity. Pre-treatment with bpv, a potent PTEN inhibitor, and PTEN antisense nucleotides decreased PTEN and GSK-3β activity and caused alterations in Tau phosphorylation. Neuronal apoptosis was also reduced. The PTEN/Akt/GSK-3β/Tau pathway is involved in the regulation of neuronal injury, providing a novel route for protecting neurons following neonatal HI.

Nuclear PTEN functions as an essential regulator of SRF-dependent transcription to control smooth muscle differentiation.

PubMed

Horita, Henrick; Wysoczynski, Christina L; Walker, Lori A; Moulton, Karen S; Li, Marcella; Ostriker, Allison; Tucker, Rebecca; McKinsey, Timothy A; Churchill, Mair E A; Nemenoff, Raphael A; Weiser-Evans, Mary C M

2016-03-04

Vascular disease progression is associated with marked changes in vascular smooth muscle cell (SMC) phenotype and function. SMC contractile gene expression and, thus differentiation, is under direct transcriptional control by the transcription factor, serum response factor (SRF); however, the mechanisms dynamically regulating SMC phenotype are not fully defined. Here we report that the lipid and protein phosphatase, PTEN, has a novel role in the nucleus by functioning as an indispensible regulator with SRF to maintain the differentiated SM phenotype. PTEN interacts with the N-terminal domain of SRF and PTEN-SRF interaction promotes SRF binding to essential promoter elements in SM-specific genes. Factors inducing phenotypic switching promote loss of nuclear PTEN through nucleo-cytoplasmic translocation resulting in reduced myogenically active SRF, but enhanced SRF activity on target genes involved in proliferation. Overall decreased expression of PTEN was observed in intimal SMCs of human atherosclerotic lesions underlying the potential clinical importance of these findings.

Loss of PTEN expression is associated with aggressive behavior and poor prognosis in Middle Eastern triple-negative breast cancer.

PubMed

Beg, Shaham; Siraj, Abdul K; Prabhakaran, Sarita; Jehan, Zeenath; Ajarim, Dahish; Al-Dayel, Fouad; Tulbah, Asma; Al-Kuraya, Khawla S

2015-06-01

PTEN is a tumor suppressor that negatively regulates the PI3 K-AKT signaling pathway which is involved in the pathogenesis of many different tumor types and serves as a prognostic marker in breast cancer. However, the significance of the role of PTEN in Middle Eastern ethnic breast cancer has not been explored especially with the fact that breast cancer originating from this ethnic population tend to behave more aggressively than breast cancer in the west. In this study, we analyzed PTEN alteration in a tissue microarray format containing more than 1000 primary breast cancers with clinical follow-up data. Tissue Microarray sections were analyzed for protein expression and copy number change using immunohistochemistry and fluorescence in situ hybridization. Loss of PTEN immunostaining was observed in 77 % of the cases. PTEN loss was significantly associated with large tumor size (p = 0.0030), high grade (p = 0.0281), tumor recurrence (p = 0.0333), and triple-negative breast cancers (p = 0.0086). PTEN loss in triple-negative breast cancers was significantly associated with rapid tumor cell proliferation (p = 0.0396) and poor prognosis (p = 0.0408). PTEN deletion was found only in 60 cases (6.4 %). Loss of PTEN protein expression occurs at high frequency in Middle Eastern breast cancer. PTEN inactivation may potentially lead to an aggressive behavior of tumor cells through stimulation of tumor cell proliferation. Furthermore, PTEN signaling pathway might be used as potential therapeutic target in triple-negative breast cancers since loss of its expression is shown to be significantly associated with this aggressive subtype of breast cancer.

A common variation of the PTEN gene is associated with peripheral insulin resistance.

PubMed

Grinder-Hansen, L; Ribel-Madsen, R; Wojtaszewski, J F P; Poulsen, P; Grunnet, L G; Vaag, A

2016-09-01

Phosphatase and tensin homologue (PTEN) reduces insulin sensitivity by inhibiting the phosphatidylinositol 3-kinase (PI3K)/v-akt murine thymoma viral oncogene homologue (Akt) pathway. This study investigated how a common single nucleotide polymorphism near PTEN, previously associated with fasting levels of plasma insulin and glucose, influences in vivo glucose metabolism and insulin signalling. The primary outcome measure was the gene variant's association with peripheral glucose disposal rate and, secondarily, whether this association was explained by altered activities of PTEN targets PI3K and Akt. A total of 183 normoglycaemic Danes, including 158 twins and 25 singletons, were genotyped for PTEN rs11202614, which is in complete linkage disequilibrium with rs2142136 and rs10788575, which have also been reported in association with glycaemic traits and type 2 diabetes (T2D). Hepatic and peripheral insulin sensitivity was measured using tracer and euglycaemic-hyperinsulinaemic clamp techniques; insulin secretion was assessed by intravenous glucose tolerance test; and muscle biopsies were taken during insulin infusion from 150 twins for measurement of PI3K and Akt activities. The minor G allele of PTEN rs11202614 was associated with elevated fasting plasma insulin levels and a decreased peripheral glucose disposal rate, but not with the hepatic insulin resistance index or insulin secretion measured as the first-phase insulin response and disposition index. The single nucleotide polymorphism was not associated with either PI3K or Akt activities. A common PTEN variation is associated with peripheral insulin resistance and subsequent risk of developing T2D. However, the association with insulin resistance is not explained by decreased proximal insulin signalling in skeletal muscle. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Second Malignant Neoplasms in Patients With Cowden Syndrome With Underlying Germline PTEN Mutations

PubMed Central

Ngeow, Joanne; Stanuch, Kim; Mester, Jessica L.; Barnholtz-Sloan, Jill S.; Eng, Charis

2014-01-01

Purpose Patients with Cowden syndrome (CS) with underlying germline PTEN mutations are at increased risk of breast, thyroid, endometrial, and renal cancers. To our knowledge, risk of subsequent cancers in these patients has not been previously explored or quantified. Patients and Methods We conducted a 7-year multicenter prospective study (2005 to 2012) of patients with CS or CS-like disease, all of whom underwent comprehensive PTEN mutational analysis. Second malignant neoplasms (SMNs) were ascertained by medical records and confirmed by pathology reports. Standardized incidence ratios (SIRs) for all SMNs combined and for breast, thyroid, endometrial, and renal cancers were calculated. Results Of the 2,912 adult patients included in our analysis, 2,024 had an invasive cancer history. Germline pathogenic PTEN mutations (PTEN mutation positive) were identified in 114 patients (5.6%). Of these 114 patients, 46 (40%) had an SMN. Median age of SMN diagnosis was 50 years (range, 21 to 71 years). Median interval between primary cancer and SMN was 5 years (range, < 1 to 35 years). Of the 51 PTEN mutation–positive patients who presented with primary breast cancer, 11 (22%) had a subsequent new primary breast cancer and 10-year second breast cancer cumulative risk of 29% (95% CI, 15.3 to 43.7). Risk of SMNs compared with that of the general population was significantly elevated for all cancers (SIR, 7.74; 95% CI, 5.84 to 10.07), specifically for breast (SIR, 8.92; 95% CI, 5.85 to 13.07), thyroid (SIR, 5.83; 95% CI, 3.01 to 10.18), and endometrial SMNs (SIR, 14.08.07; 95% CI, 7.10 to 27.21). Conclusion Patients with CS with germline PTEN mutations are at higher risk for SMNs compared with the general population. Prophylactic mastectomy should be considered on an individual basis given the significant risk of subsequent breast cancer. PMID:24778394

Redox Signaling via Oxidative Inactivation of PTEN Modulates Pressure-Dependent Myogenic Tone in Rat Middle Cerebral Arteries

PubMed Central

Gebremedhin, Debebe; Terashvili, Maia; Wickramasekera, Nadi; Zhang, David X.; Rau, Nicole; Miura, Hiroto; Harder, David R.

2013-01-01

The present study examined the level of generation of reactive oxygen species (ROS) and roles of inactivation of the phosphatase PTEN and the PI3K/Akt signaling pathway in response to an increase in intramural pressure-induced myogenic cerebral arterial constriction. Step increases in intraluminal pressure of cannulated cerebral arteries induced myogenic constriction and concomitant formation of superoxide (O2 .−) and its dismutation product hydrogen peroxide (H2O2) as determined by fluorescent HPLC analysis, microscopic analysis of intensity of dihydroethidium fluorescence and attenuation of pressure-induced myogenic constriction by pretreatment with the ROS scavenger 4,hydroxyl-2,2,6,6-tetramethylpiperidine1-oxyl (tempol) or Mito-tempol or MitoQ in the presence or absence of PEG-catalase. An increase in intraluminal pressure induced oxidation of PTEN and activation of Akt. Pharmacological inhibition of endogenous PTEN activity potentiated pressure-dependent myogenic constriction and caused a reduction in NPo of a 238 pS arterial KCa channel current and an increase in [Ca2+]i level in freshly isolated cerebral arterial muscle cells (CAMCs), responses that were attenuated by Inhibition of the PI3K/Akt pathway. These findings demonstrate an increase in intraluminal pressure induced increase in ROS production triggered redox-sensitive signaling mechanism emanating from the cross-talk between oxidative inactivation of PTEN and activation of the PI3K/Akt signaling pathway that involves in the regulation of pressure-dependent myogenic cerebral arterial constriction. PMID:23861911

Redox signaling via oxidative inactivation of PTEN modulates pressure-dependent myogenic tone in rat middle cerebral arteries.

PubMed

Gebremedhin, Debebe; Terashvili, Maia; Wickramasekera, Nadi; Zhang, David X; Rau, Nicole; Miura, Hiroto; Harder, David R

2013-01-01

The present study examined the level of generation of reactive oxygen species (ROS) and roles of inactivation of the phosphatase PTEN and the PI3K/Akt signaling pathway in response to an increase in intramural pressure-induced myogenic cerebral arterial constriction. Step increases in intraluminal pressure of cannulated cerebral arteries induced myogenic constriction and concomitant formation of superoxide (O2 (.-)) and its dismutation product hydrogen peroxide (H2O2) as determined by fluorescent HPLC analysis, microscopic analysis of intensity of dihydroethidium fluorescence and attenuation of pressure-induced myogenic constriction by pretreatment with the ROS scavenger 4,hydroxyl-2,2,6,6-tetramethylpiperidine1-oxyl (tempol) or Mito-tempol or MitoQ in the presence or absence of PEG-catalase. An increase in intraluminal pressure induced oxidation of PTEN and activation of Akt. Pharmacological inhibition of endogenous PTEN activity potentiated pressure-dependent myogenic constriction and caused a reduction in NPo of a 238 pS arterial KCa channel current and an increase in [Ca(2+)]i level in freshly isolated cerebral arterial muscle cells (CAMCs), responses that were attenuated by Inhibition of the PI3K/Akt pathway. These findings demonstrate an increase in intraluminal pressure induced increase in ROS production triggered redox-sensitive signaling mechanism emanating from the cross-talk between oxidative inactivation of PTEN and activation of the PI3K/Akt signaling pathway that involves in the regulation of pressure-dependent myogenic cerebral arterial constriction.

miR-17 inhibitor suppressed osteosarcoma tumor growth and metastasis via increasing PTEN expression

DOE Office of Scientific and Technical Information (OSTI.GOV)

Gao, Yong, E-mail: gaoyongunion@163.com; Luo, Ling-hui; Li, Shuai

2014-02-07

Highlights: • miR-17 was increased in OS tissues and cell lines. • Inhibition of miR-17 suppressed OS cell proliferation. • Inhibition of miR-17 suppressed OS cell migration and invasion. • PTEN was a target of miR-17. • miR-17 was negatively correlated with PTEN in OS tissues. - Abstract: MicroRNAs (miRNAs) play essential roles in cancer development and progression. Here, we investigated the role of miR-17 in the progression and metastasis of osteosarcoma (OS). miR-17 was frequently increased in OS tissues and cell lines. Inhibition of miR-17 in OS cell lines substantially suppressed cell proliferation, migration, and invasion. Phosphatase and tensinmore » homolog (PTEN) was identified as a target of miR-17, and ectopic expression of miR-17 inhibited PTEN by direct binding to its 3′-untranslated region (3′-UTR). Expression of miR-17 was negatively correlated with PTEN in OS tissues. Together, these findings indicate that miR-17 acts as an oncogenic miRNA and may contribute to the progression and metastasis of OS, suggesting miR-17 as a potential novel diagnostic and therapeutic target of OS.« less

Methodological aspects of the molecular and histological study of prostate cancer: focus on PTEN.

PubMed

Ugalde-Olano, Aitziber; Egia, Ainara; Fernández-Ruiz, Sonia; Loizaga-Iriarte, Ana; Zuñiga-García, Patricia; Garcia, Stephane; Royo, Félix; Lacasa-Viscasillas, Isabel; Castro, Erika; Cortazar, Ana R; Zabala-Letona, Amaia; Martín-Martín, Natalia; Arruabarrena-Aristorena, Amaia; Torrano-Moya, Verónica; Valcárcel-Jiménez, Lorea; Sánchez-Mosquera, Pilar; Caro-Maldonado, Alfredo; González-Tampan, Jorge; Cachi-Fuentes, Guido; Bilbao, Elena; Montero, Rocío; Fernández, Sara; Arrieta, Edurne; Zorroza, Kerman; Castillo-Martín, Mireia; Serra, Violeta; Salazar, Eider; Macías-Cámara, Nuria; Tabernero, Jose; Baselga, Jose; Cordón-Cardo, Carlos; Aransay, Ana M; Villar, Amaia Del; Iovanna, Juan L; Falcón-Pérez, Juan M; Unda, Miguel; Bilbao, Roberto; Carracedo, Arkaitz

2015-05-01

Prostate cancer is among the most frequent cancers in men, and despite its high rate of cure, the high number of cases results in an elevated mortality worldwide. Importantly, prostate cancer incidence is dramatically increasing in western societies in the past decades, suggesting that this type of tumor is exquisitely sensitive to lifestyle changes. Prostate cancer frequently exhibits alterations in the PTEN gene (inactivating mutations or gene deletions) or at the protein level (reduced protein expression or altered sub-cellular compartmentalization). The relevance of PTEN in this type of cancer is further supported by the fact that the sole deletion of PTEN in the murine prostate epithelium recapitulates many of the features of the human disease. In order to study the molecular alterations in prostate cancer, we need to overcome the methodological challenges that this tissue imposes. In this review we present protocols and methods, using PTEN as proof of concept, to study different molecular characteristics of prostate cancer. Copyright © 2015. Published by Elsevier Inc.

PTEN Loss Increases the Connectivity of Fast Synaptic Motifs and Functional Connectivity in a Developing Hippocampal Network

PubMed Central

McCabe, Matthew P.; Chen, Hongmei; Swann, John W.

2017-01-01

Changes in synaptic strength and connectivity are thought to be a major mechanism through which many gene variants cause neurological disease. Hyperactivation of the PI3K-mTOR signaling network, via loss of function of repressors such as PTEN, causes epilepsy in humans and animal models, and altered mTOR signaling may contribute to a broad range of neurological diseases. Changes in synaptic transmission have been reported in animal models of PTEN loss; however, the full extent of these changes, and their effect on network function, is still unknown. To better understand the scope of these changes, we recorded from pairs of mouse hippocampal neurons cultured in a two-neuron microcircuit configuration that allowed us to characterize all four major connection types within the hippocampus. Loss of PTEN caused changes in excitatory and inhibitory connectivity, and these changes were postsynaptic, presynaptic, and transynaptic, suggesting that disruption of PTEN has the potential to affect most connection types in the hippocampal circuit. Given the complexity of the changes at the synaptic level, we measured changes in network behavior after deleting Pten from neurons in an organotypic hippocampal slice network. Slices containing Pten-deleted neurons showed increased recruitment of neurons into network bursts. Importantly, these changes were not confined to Pten-deleted neurons, but involved the entire network, suggesting that the extensive changes in synaptic connectivity rewire the entire network in such a way that promotes a widespread increase in functional connectivity. SIGNIFICANCE STATEMENT Homozygous deletion of the Pten gene in neuronal subpopulations in the mouse serves as a valuable model of epilepsy caused by mTOR hyperactivation. To better understand how gene deletions lead to altered neuronal activity, we investigated the synaptic and network effects that occur 1 week after Pten deletion. PTEN loss increased the connectivity of all four types of hippocampal

Relevance of miR-21 in regulation of tumor suppressor gene PTEN in human cervical cancer cells.

PubMed

Peralta-Zaragoza, Oscar; Deas, Jessica; Meneses-Acosta, Angélica; De la O-Gómez, Faustino; Fernández-Tilapa, Gloria; Gómez-Cerón, Claudia; Benítez-Boijseauneau, Odelia; Burguete-García, Ana; Torres-Poveda, Kirvis; Bermúdez-Morales, Victor Hugo; Madrid-Marina, Vicente; Rodríguez-Dorantes, Mauricio; Hidalgo-Miranda, Alfredo; Pérez-Plasencia, Carlos

2016-03-14

Expression of the microRNA miR-21 has been found to be altered in almost all types of cancers and it has been classified as an oncogenic microRNA or oncomir. Due to the critical functions of its target proteins in various signaling pathways, miR-21 is an attractive target for genetic and pharmacological modulation in various cancers. Cervical cancer is the second most common cause of death from cancer in women worldwide and persistent HPV infection is the main etiologic agent. This malignancy merits special attention for the development of new treatment strategies. In the present study we analyze the role of miR-21 in cervical cancer cells. To identify the downstream cellular target genes of upstream miR-21, we silenced endogenous miR-21 expression in a cervical intraepithelial neoplasia-derived cell lines using siRNAs. The effect of miR-21 on gene expression was assessed in cervical cancer cells transfected with the siRNA expression plasmid pSIMIR21. We identified the tumor suppressor gene PTEN as a target of miR-21 and determined the mechanism of its regulation throughout reporter construct plasmids. Using this model, we analyzed the expression of miR-21 and PTEN as well as functional effects such as autophagy and apoptosis induction. In SiHa cells, there was an inverse correlation between miR-21 expression and PTEN mRNA level as well as PTEN protein expression in cervical cancer cells. Transfection with the pSIMIR21 plasmid increased luciferase reporter activity in construct plasmids containing the PTEN-3'-UTR microRNA response elements MRE21-1 and MRE21-2. The role of miR-21 in cell proliferation was also analyzed in SiHa and HeLa cells transfected with the pSIMIR21 plasmid, and tumor cells exhibited markedly reduced cell proliferation along with autophagy and apoptosis induction. We conclude that miR-21 post-transcriptionally down-regulates the expression of PTEN to promote cell proliferation and cervical cancer cell survival. Therefore, it may be a potential

Variable Expression of PIK3R3 and PTEN in Ewing Sarcoma Impacts Oncogenic Phenotypes

PubMed Central

Niemeyer, Brian F.; Parrish, Janet K.; Spoelstra, Nicole S.; Joyal, Teresa; Richer, Jennifer K.; Jedlicka, Paul

2015-01-01

Ewing Sarcoma is an aggressive malignancy of bone and soft tissue affecting children and young adults. Ewing Sarcoma is driven by EWS/Ets fusion oncoproteins, which cause widespread alterations in gene expression in the cell. Dysregulation of receptor tyrosine kinase signaling, particularly involving IGF-1R, also plays an important role in Ewing Sarcoma pathogenesis. However, the basis of this dysregulation, including the relative contribution of EWS/Ets-dependent and independent mechanisms, is not well understood. In the present study, we identify variable expression of two modifiers of PI3K signaling activity, PIK3R3 and PTEN, in Ewing Sarcoma, and examine the consequences of this on PI3K pathway regulation and oncogenic phenotypes. Our findings indicate that PIK3R3 plays a growth-promotional role in Ewing Sarcoma, but suggest that this role is not strictly dependent on regulation of PI3K pathway activity. We further show that expression of PTEN, a well-established, potent tumor suppressor, is lost in a subset of Ewing Sarcomas, and that this loss strongly correlates with high baseline PI3K pathway activity in cell lines. In support of functional importance of PTEN loss in Ewing Sarcoma, we show that re-introduction of PTEN into two different PTEN-negative Ewing Sarcoma cell lines results in downregulation of PI3K pathway activity, and sensitization to the IGF-1R small molecule inhibitor OSI-906. Our findings also suggest that PTEN levels may contribute to sensitivity of Ewing Sarcoma cells to the microtubule inhibitor vincristine, a relevant chemotherapeutic agent in this cancer. Our studies thus identify PIK3R3 and PTEN as modifiers of oncogenic phenotypes in Ewing Sarcoma, with potential clinical implications. PMID:25603314

17betaE2 promotes cell proliferation in endometriosis by decreasing PTEN via NFkappaB-dependent pathway.

PubMed

Zhang, Hui; Zhao, Xingbo; Liu, Shu; Li, Jijun; Wen, Zeqing; Li, Mingjiang

2010-04-12

The objective of this study was to explore the mechanism of phosphatase and tensin homolog (PTEN) loss in endometriosis. We found that aberrant PTEN expression and mitogen-activated protein kinases (MAPK)/ERK, phosphoinositide 3-kinase (PI3K)/AKt, and nuclear factor-kappaB (NFkappaB) signaling overactivities coexisted in endometriosis. In vitro, 17beta-estradiol rapidly activated the 3 pathways in endometriotic cells and specific inhibitions on the 3 pathways respectively blocked 17beta-estradiol-induced cell proliferation. 17beta-estradiol suppressed PTEN transcription and expression in endometriotic cells which was abolished by specific NFkappaB inhibition. Total/nuclear PTEN-loss and MAPK/ERK, PI3K/AKt, and NFkappaB signal overactivities coexist in endometriosis. In vitro, 17beta-estradiol can promotes cell proliferation in endometriosis by activating PI3K/AKt pathway via an NFkappaB/PTEN-dependent pathway. For the first time we propose the possibility of the presence of a positive feedback-loop: 17beta-estradiol-->high NFkappaB-->low PTEN-->high PI3K-->high NFkappaB, in endometriosis, which may finally promote the proliferation of ectopic endometrial epithelial cells and in turn contributes to the progression of the disease.

Constitutively expressed COX-2 in osteoblasts positively regulates Akt signal transduction via suppression of PTEN activity.

PubMed

Li, Ching-Ju; Chang, Je-Ken; Wang, Gwo-Jaw; Ho, Mei-Ling

2011-02-01

Cyclooxygenase-2 (COX-2) is thought to be an inducible enzyme, but increasing reports indicate that COX-2 is constitutively expressed in several organs. The status of COX-2 expression in bone and its physiological role remains undefined. Non-selective non-steroidal anti-inflammatory drugs (NSAIDs) and selective COX-2 inhibitors, which commonly suppress COX-2 activity, were reported to suppress osteoblast proliferation via Akt/FOXO3a/p27(Kip1) signaling, suggesting that COX-2 may be the key factor of the suppressive effects of NSAIDs on proliferation. Although Akt activation correlates with PTEN deficiency and cell viability, the role of COX-2 on PTEN/Akt regulation remains unclear. In this study, we hypothesized that COX-2 may be constitutively expressed in osteoblasts and regulate PTEN/Akt-related proliferation. We examined the localization and co-expression of COX-2 and p-Akt in normal mouse femurs and in cultured mouse (mOBs) and human osteoblasts (hOBs). Our results showed that osteoblasts adjacent to the trabeculae, periosteum and endosteum in mouse femurs constitutively expressed COX-2, while COX-2 co-expressed with p-Akt in osteoblasts sitting adjacent to trabeculae in vivo, and in mOBs and hOBs in vitro. We further used COX-2 siRNA to test the role of COX-2 in Akt signaling in hOBs; COX-2 silencing significantly inhibited PTEN phosphorylation, enhanced PTEN activity, and suppressed p-Akt level and proliferation. However, replenishment of the COX-2 enzymatic product, PGE2, failed to reverse COX-2-dependent Akt phosphorylation. Furthermore, transfection with recombinant human COX-2 (rhCOX-2) significantly reversed COX-2 siRNA-suppressed PTEN phosphorylation, but this effect was reduced when the enzymatic activity of rhCOX-2 was blocked. This finding indicated that the effect of COX-2 on PTEN/Akt signaling is not related to PGE2 but still dependent on COX-2 enzymatic activity. Conversely, COX-1 silencing did not affect PTEN/Akt signaling. Our findings provide

High-resolution Structures of Protein-Membrane Complexes by Neutron Reflection and MD Simulation: Membrane Association of the PTEN Tumor Suppressor

NASA Astrophysics Data System (ADS)

Lösche, Matthias

2012-02-01

The lipid matrix of biomembranes is an in-plane fluid, thermally and compositionally disordered leaflet of 5 nm thickness and notoriously difficult to characterize in structural terms. Yet, biomembranes are ubiquitous in the cell, and membrane-bound proteins are implicated in a variety of signaling pathways and intra-cellular transport. We developed methodology to study proteins associated with model membranes using neutron reflection measurements and showed recently that this approach can resolve the penetration depth and orientation of membrane proteins with ångstrom resolution if their crystal or NMR structure is known. Here we apply this technology to determine the membrane bindung and unravel functional details of the PTEN phosphatase, a key player in the PI3K apoptosis pathway. PTEN is an important regulatory protein and tumor suppressor that performs its phosphatase activity as an interfacial enzyme at the plasma membrane-cytoplasm boundary. Acting as an antagonist to phosphoinositide-3-kinase (PI3K) in cell signaling, it is deleted in many human cancers. Despite its importance in regulating the levels of the phosphoinositoltriphosphate PI(3,4,5)P3, there is little understanding of how PTEN binds to membranes, is activated and then acts as a phosphatase. We investigated the structure and function of PTEN by studying its membrane affinity and localization on in-plane fluid, thermally disordered synthetic membrane models. The membrane association of the protein depends strongly on membrane composition, where phosphatidylserine (PS) and phosphatidylinositol diphosphate (PI(4,5)P2) act synergetically in attracting the enzyme to the membrane surface. Membrane affinities depend strongly on membrane fluidity, which suggests multiple binding sites on the protein for PI(4,5)P2. Neutron reflection measurements show that the PTEN phosphatase ``scoots'' along the membrane surface (penetration < 5 å) but binds the membrane tightly with its two major domains, the C2 and

Exploring the Interaction between TSC2, PTEN, and the NMDA Receptor in Animal Models of Tuberous Sclerosis

DTIC Science & Technology

2014-09-01

Sunnen CN, Crowell B, Lee GH, Anderson AE, and D’Arcangelo G. Examination of the Role of Pten in Ionotropic Glutamate Receptor Expression. National...PTEN, and the NMDA Receptor in Animal Models of Tuberous Sclerosis PRINCIPAL INVESTIGATOR: D’Arcangelo, Gabriella CONTRACTING...June 2014 4. TITLE AND SUBTITLE Exploring the Interaction between TSC2, PTEN, and the NMDA Receptor in Animal Models of Tuberous Sclerosis 5a

Conditional Deletion of the Pten Gene in the Mouse Prostate Induces Prostatic Intraepithelial Neoplasms at Early Ages but a Slow Progression to Prostate Tumors

PubMed Central

Zhu, Chunfang; Lee, Suk Hyung; Ye, Ding-Wei; Luong, Richard; Sun, Zijie

2013-01-01

The PTEN tumor suppressor gene is frequently inactivated in human prostate cancer. Using Osr1 (odd skipped related 1)-Cre mice, we generated a novel conditional Pten knockout mouse strain, PtenLoxP:Osr1-Cre. Conditional biallelic and monoallelic Pten knockout mice were viable. Deletion of Pten expression was detected in the prostate of PtenLoxP/LoxP:Osr1-Cre mice as early as 2 weeks of age. Intriguingly, PtenLoxP/LoxP:Osr1-Cre mice develop high-grade prostatic intraepithelial neoplasms (PINs) with high penetrance as early as one-month of age, and locally invasive prostatic tumors after 12-months of age. PtenLoxP/+:Osr1-Cre mice show only mild oncogenic changes after 8-weeks of age. Castration of PtenLoxP/LoxP:Osr1-Cre mice shows no significant regression of prostate tumors, although a shift of androgen receptor (AR) staining from the nuclei to cytoplasm is observed in Pten null tumor cells of castrated mice. Enhanced Akt activity is observed in Pten null tumor cells of castrated PtenLoxP/LoxP:Osr1-Cre. This study provides a novel mouse model that can be used to investigate a primary role of Pten in initiating oncogenic transformation in the prostate and to examine other genetic and epigenetic changes that are required for tumor progression in the mouse prostate. PMID:23308230

Role of PTEN in the Tumor Microenvironment

DTIC Science & Technology

2009-06-01

OS, Boers M, Molthoff CF, van Diest PJ. (2008). Hexokinase III, cyclin A and galectin - 3 are overexpressed in malignant follicular thyroid nodules...2009 2. REPORT TYPE Annual 3 . DATES COVERED (From - To) 4. TITLE AND SUBTITLE Role of PTEN in the Tumor Microenvironment 5a. CONTRACT NUMBER...

The melatonin-MT1 receptor axis modulates tumor growth in PTEN-mutated gliomas.

PubMed

Ma, Huihui; Wang, Zhen; Hu, Lei; Zhang, Shangrong; Zhao, Chenggang; Yang, Haoran; Wang, Hongzhi; Fang, Zhiyou; Wu, Lijun; Chen, Xueran

2018-02-19

More than 40% of glioma patients have tumors that harbor PTEN (phosphatase and tensin homologue deleted on chromosome ten) mutations; this disease is associated with poor therapeutic resistance and outcome. Such mutations are linked to increased cell survival and growth, decreased apoptosis, and drug resistance; thus, new therapeutic strategies focusing on inhibiting glioma tumorigenesis and progression are urgently needed. Melatonin, an indolamine produced and secreted predominantly by the pineal gland, mediates a variety of physiological functions and possesses antioxidant and antitumor properties. Here, we analyzed the relationship between PTEN and the inhibitory effect of melatonin in primary human glioma cells and cultured glioma cell lines. The results showed that melatonin can inhibit glioma cell growth both in culture and in vivo. This inhibition was associated with PTEN levels, which significantly correlated with the expression level of MT1 in patients. In fact, c-fos-mediated MT1 was shown to be a key modulator of the effect of melatonin on gliomas that harbor wild type PTEN. Taken together, these data suggest that melatonin-MT1 receptor complexes represent a potential target for the treatment of glioma. Copyright © 2018 Elsevier Inc. All rights reserved.

Nuclear PTEN localization contributes to DNA damage repair in Endometrial cancer and could have a diagnostic benefit for therapeutic management of the disease.

PubMed

Mukherjee, Ananda; Patterson, Amanda L; George, Jitu W; Carpenter, Tyler J; Madaj, Zachary B; Hostetter, Galen; Risinger, John I; Teixeira, Jose M

2018-06-13

Endometrial adenocarcinoma (EndoCA) is the most common gynecological cancer type in the US, and its incidence is increasing. The majority of patients are disease-free after surgical resection of stage I tumors, which is often followed by radiation therapy, but most patients with advanced disease recur and have a poor prognosis, largely because the tumors become refractory to cytotoxic chemotherapies. PTEN, a commonly mutated tumor suppressor in EndoCAs, is well known for its ability to inhibit the AKT/mTOR signaling pathway. Nuclear functions for PTEN have been proposed as well, but whether those affect EndoCA development, progression, or outcomes is not well understood. Using immunohistochemistry, nuclear PTEN expression was observed in approximately half of EndoCA patient tumors, independent of grade and cytoplasmic PTEN expression. Higher levels of the DNA damage response (DDR) marker, yH2AX, were observed by immunohistochemistry and immunofluorescence in human EndoCA tumor sections that were PTEN-negative, in murine EndoCA tissues that were genetically modified to be PTEN-null, and in Ishikawa EndoCA cells, which do not express endogenous PTEN. Over-expression of exogenous PTEN-WT or PTEN-NLS, a modified PTEN with an added nuclear localization signal, significantly improved both DDR and G2/M transition in Ishikawa cells treated with a DNA damaging agent. Whereas PARP inhibition with Olaparib was not as effective in Ishikawa cells expressing native or PTEN-NLS, inhibition with Talazoparib was not affected by PTEN overexpression. These results suggest that nuclear PTEN subcellular localization in human EndoCA could be diagnostic when considering DDR therapeutic intervention. Copyright ©2018, American Association for Cancer Research.

Overexpression of calcium-activated potassium channels underlies cortical dysfunction in a model of PTEN-associated autism.

PubMed

Garcia-Junco-Clemente, Pablo; Chow, David K; Tring, Elaine; Lazaro, Maria T; Trachtenberg, Joshua T; Golshani, Peyman

2013-11-05

De novo phosphatase and tensin homolog on chromosome ten (PTEN) mutations are a cause of sporadic autism. How single-copy loss of PTEN alters neural function is not understood. Here we report that Pten haploinsufficiency increases the expression of small-conductance calcium-activated potassium channels. The resultant augmentation of this conductance increases the amplitude of the afterspike hyperpolarization, causing a decrease in intrinsic excitability. In vivo, this change in intrinsic excitability reduces evoked firing rates of cortical pyramidal neurons but does not alter receptive field tuning. The decreased in vivo firing rate is not associated with deficits in the dendritic integration of synaptic input or with changes in dendritic complexity. These findings identify calcium-activated potassium channelopathy as a cause of cortical dysfunction in the PTEN model of autism and provide potential molecular therapeutic targets.

Embryonic epithelial Pten deletion through Nkx2.1-cre leads to thyroid tumorigenesis in a strain-dependent manner

PubMed Central

Tiozzo, Caterina; Danopoulos, Soula; Lavarreda-Pearce, Maria; Baptista, Sheryl; Varimezova, Radka; Al Alam, Denise; Warburton, David; Virender, Rehan; De Langhe, Stijn; Di Cristofano, Antonio

2014-01-01

Even though the role of the tyrosine phosphatase Pten as a tumor suppressor gene has been well established in thyroid cancer, its role during thyroid development is still elusive. We therefore targeted Pten deletion in the thyroid epithelium by crossing Ptenflox/flox with a newly developed Nkx2.1-cre driver line in the BALB/c and C57BL/6 genetic backgrounds. C57BL/6 homozygous Pten mutant mice died around 2 weeks of age due to tracheal and esophageal compression by a hyperplasic thyroid. By contrast, BALB/c homozygous Pten mutant mice survived up to 2 years, but with a slightly increased thyroid volume. Characterization of the thyroid glands from C57BL/6 homozygous Pten mutant mice at postnatal day 14 (PN14) showed abnormally enlarged tissue with areas of cellular hyperplasia, disruption of the normal architecture, and follicular degeneration. In addition, differing degrees of hypothyroidism, thyroxine (T4) decrease, and thyroid-stimulating hormone elevation between the strains in the mutants and the heterozygous mutant were detected at PN14. Finally, C57BL/6 heterozygous Pten mutant mice developed thyroid tumors after 2 years of age. Our results indicate that Pten has a pivotal role in thyroid development and its deletion results in thyroid tumor formation, with the timing and severity of the tumor depending on the particular genetic background. PMID:22167068

MicroRNA-486–dependent modulation of DOCK3/PTEN/AKT signaling pathways improves muscular dystrophy–associated symptoms

PubMed Central

Alexander, Matthew S.; Casar, Juan Carlos; Motohashi, Norio; Vieira, Natássia M.; Eisenberg, Iris; Marshall, Jamie L.; Gasperini, Molly J.; Lek, Angela; Myers, Jennifer A.; Estrella, Elicia A.; Kang, Peter B.; Shapiro, Frederic; Rahimov, Fedik; Kawahara, Genri; Widrick, Jeffrey J.; Kunkel, Louis M.

2014-01-01

Duchenne muscular dystrophy (DMD) is caused by mutations in the gene encoding dystrophin, which results in dysfunctional signaling pathways within muscle. Previously, we identified microRNA-486 (miR-486) as a muscle-enriched microRNA that is markedly reduced in the muscles of dystrophin-deficient mice (Dmdmdx-5Cv mice) and in DMD patient muscles. Here, we determined that muscle-specific transgenic overexpression of miR-486 in muscle of Dmdmdx-5Cv mice results in reduced serum creatine kinase levels, improved sarcolemmal integrity, fewer centralized myonuclei, increased myofiber size, and improved muscle physiology and performance. Additionally, we identified dedicator of cytokinesis 3 (DOCK3) as a miR-486 target in skeletal muscle and determined that DOCK3 expression is induced in dystrophic muscles. DOCK3 overexpression in human myotubes modulated PTEN/AKT signaling, which regulates muscle hypertrophy and growth, and induced apoptosis. Furthermore, several components of the PTEN/AKT pathway were markedly modulated by miR-486 in dystrophin-deficient muscle. Skeletal muscle–specific miR-486 overexpression in Dmdmdx-5Cv animals decreased levels of DOCK3, reduced PTEN expression, and subsequently increased levels of phosphorylated AKT, which resulted in an overall beneficial effect. Together, these studies demonstrate that stable overexpression of miR-486 ameliorates the disease progression of dystrophin-deficient skeletal muscle. PMID:24789910

PTEN Loss Increases the Connectivity of Fast Synaptic Motifs and Functional Connectivity in a Developing Hippocampal Network.

PubMed

Barrows, Caitlynn M; McCabe, Matthew P; Chen, Hongmei; Swann, John W; Weston, Matthew C

2017-09-06

Changes in synaptic strength and connectivity are thought to be a major mechanism through which many gene variants cause neurological disease. Hyperactivation of the PI3K-mTOR signaling network, via loss of function of repressors such as PTEN, causes epilepsy in humans and animal models, and altered mTOR signaling may contribute to a broad range of neurological diseases. Changes in synaptic transmission have been reported in animal models of PTEN loss; however, the full extent of these changes, and their effect on network function, is still unknown. To better understand the scope of these changes, we recorded from pairs of mouse hippocampal neurons cultured in a two-neuron microcircuit configuration that allowed us to characterize all four major connection types within the hippocampus. Loss of PTEN caused changes in excitatory and inhibitory connectivity, and these changes were postsynaptic, presynaptic, and transynaptic, suggesting that disruption of PTEN has the potential to affect most connection types in the hippocampal circuit. Given the complexity of the changes at the synaptic level, we measured changes in network behavior after deleting Pten from neurons in an organotypic hippocampal slice network. Slices containing Pten -deleted neurons showed increased recruitment of neurons into network bursts. Importantly, these changes were not confined to Pten -deleted neurons, but involved the entire network, suggesting that the extensive changes in synaptic connectivity rewire the entire network in such a way that promotes a widespread increase in functional connectivity. SIGNIFICANCE STATEMENT Homozygous deletion of the Pten gene in neuronal subpopulations in the mouse serves as a valuable model of epilepsy caused by mTOR hyperactivation. To better understand how gene deletions lead to altered neuronal activity, we investigated the synaptic and network effects that occur 1 week after Pten deletion. PTEN loss increased the connectivity of all four types of

Age-related clinical and biological features of PTEN abnormalities in T-cell acute lymphoblastic leukaemia.

PubMed

Tesio, M; Trinquand, A; Ballerini, P; Hypolite, G; Lhermitte, L; Petit, A; Ifrah, N; Baruchel, A; Dombret, H; Macintyre, E; Asnafi, V

2017-12-01

The tumour suppressor gene PTEN is commonly altered in T-cell acute lymphoblastic leukaemia but its prognostic impact is still debated. We screened a cohort of 573 fully characterised adult and paediatric T-cell acute lymphoblastic leukaemia (T-ALL) patients for genomic PTEN abnormalities. PTEN-inactivating mutations and/or deletions were identified in 91 cases (16%), including 18% of paediatric (49/277) and 14% of adult cases (42/296). Thirty-four patients harboured only mutations, 12 cases demonstrated only large deletions and 9 only microdeletions. About 36 patients had combined alterations. Different mechanisms of PTEN inactivation predicted differences in the clinical outcome for both adult and paediatric patients treated according to the GRAALL03/05 and FRALLE2000 protocols. Whereas large deletions predicted lower 5-year overall survival (P=0.0053 in adults, P=0.001 in children) and disease-free survival (P=0.0009 in adults, P=0.0002 in children), mutations were not associated with a worse prognosis. The prognostic impact of PTEN loss is therefore linked to the underlying type of genomic abnormality, both in adult and paediatric T-ALLs, demonstrating that detailed analysis of the type of abnormality type would be useful to refine risk stratification.

Cooperativity Between Oncogenic PKC Epsilon and Pten Loss in Prostate Cancer Progression

DTIC Science & Technology

2015-10-01

AWARD NUMBER: W81XWH-14-1-0535 TITLE: “Cooperativity Between Oncogenic PKC Epsilon and Pten Loss in Prostate Cancer Progression” PRINCIPAL...3. DATES COVERED 30 Sep 2014 - 29 Sep 2015 4. TITLE AND SUBTITLE 5a. CONTRACT NUMBER Cooperativity Between Oncogenic PKC Epsilon and Pten Loss in...the s-econd leadi.ng caus.e of cmcer-related deaths .unong wen in thee United States. Protein kinase C epsilon (PKCs), a me-mber of the PKC £uuily

Impact of PTEN on the expression of insulin-like growth factors (IGFs) and IGF-binding proteins in human gastric adenocarcinoma cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Yi, Ho-Keun; Kim, Sun-Young; Hwang, Pyoung-Han

2005-05-13

PTEN is a tumor suppressor gene that is frequently mutated or deleted in a variety of human cancers including human gastric cancer. PTEN functions primarily as a lipid phosphatase and plays a key role in the regulation of the PI3 kinase/Akt pathway, thereby modulating cell proliferation and cell survival. On the other hand, the IGF system plays an important role in cell proliferation and cell survival via the PI3 kinase/Akt and MAP kinase pathways in many cancer cells. To characterize the impact of PTEN on the IGF-IGFR-IGFBP axis in gastric cancer, we overexpressed PTEN using an adenovirus gene transfer systemmore » in human gastric adenocarcinoma cells, SNU-484 and SNU-663, which lack PTEN. Overexpression of PTEN inhibited serum-induced as well as IGF-I-induced cell proliferation as compared to control cells. PTEN overexpression resulted in a significant decrease in the expression of IGF-I, -II, and IGF-IR. Interestingly, amongst the six IGFBPs, only IGFBP-3 was upregulated by PTEN, whereas IGFBP-4 and -6 were reduced. The IGFBP-3 promoter activity assay and Western immunoblotting demonstrate that PTEN regulates IGFBP-3 at the transcriptional level. In addition, the PI3 kinase inhibitor, LY294002, upregulates IGFBP-3 expression but downregulates IGF-I and IGF-II, indicating that PTEN controls IGFBP-3 and IGFs by an Akt-dependent pathway. These findings suggest that PTEN may inhibit antiapoptotic IGF actions not only by blocking the IGF-IGFR-induced Akt activity, but also by regulating expression of components of the IGF system, in particular, upregulation of IGFBP-3, which is known to exert antiproliferative effects through IGF-dependent and IGF-independent mechanisms in cancer cells.« less

Antibody to human α-fetoprotein inhibits cell growth of human hepatocellular carcinoma cells by resuscitating the PTEN molecule: in vitro experiments.

PubMed

Ohkawa, Kiyoshi; Asakura, Tadashi; Tsukada, Yutaka; Matsuura, Tomokazu

2017-06-01

It has been proposed that α-fetoprotein (AFP) is a new member of the intracellular signaling molecule family of the phosphoinositide 3-kinase (PI3K)/AKT signaling pathway via interaction with the phosphatase and tensin homolog (PTEN). In this study, the effects of anti-human AFP antibody on the functions of PTEN were examined using an AFP-producing human hepatoma cell line. The antibody caused significant inhibition of cell growth, compared to a normal IgG control, with the accumulation of intracellular immune complexes followed by significant reduction of cytosolic functional AFP. Decrease in the amount of AKT phosphorylated on serine (S) 473 indicated that PI3K/AKT signaling was suppressed in the cells. S380-phosphorylated PTEN increased markedly by the second day after antibody treatment, with slight but significant increase in the PTEN protein level. Since phosphorylation at S380 is critical for PTEN stability, the increase in S380-phosphorylated PTEN indicated maintenance of the number of PTEN molecules and the related potential to control PI3K/AKT signaling. p53 protein (P53) significantly, but slightly increased during antibody treatment, because PTEN expression increased the stability and function of P53 via both molecular interactions. P53 phosphorylated at S20 or at S392 dramatically increased, suggesting an increase in the stability, accumulation and activation of P53. Glucose transporter 1 (GLUT1) increased immediately after antibody treatment, pointing to a deficiency of glucose in the cells. Immunofluorescence cytology revealed that antibody-treatment re-distributed GLUT1 molecules throughout the cytoplasm with a reduction of their patchy localization on the cell surface. This suggested that translocation of GLUT1 depends on the PI3K/AKT pathway, in particular on PTEN expression. Antibody therapy targeted at AFP-producing tumor cells showed an inhibitory effect on the PI3K/AKT pathway via the liberation, restoration and functional stabilization of

PTEN modulates cell cycle progression and cell survival by regulating phosphatidylinositol 3,4,5,-trisphosphate and Akt/protein kinase B signaling pathway.

PubMed

Sun, H; Lesche, R; Li, D M; Liliental, J; Zhang, H; Gao, J; Gavrilova, N; Mueller, B; Liu, X; Wu, H

1999-05-25

To investigate the molecular basis of PTEN-mediated tumor suppression, we introduced a null mutation into the mouse Pten gene by homologous recombination in embryonic stem (ES) cells. Pten-/- ES cells exhibited an increased growth rate and proliferated even in the absence of serum. ES cells lacking PTEN function also displayed advanced entry into S phase. This accelerated G1/S transition was accompanied by down-regulation of p27(KIP1), a major inhibitor for G1 cyclin-dependent kinases. Inactivation of PTEN in ES cells and in embryonic fibroblasts resulted in elevated levels of phosphatidylinositol 3,4,5,-trisphosphate, a product of phosphatidylinositol 3 kinase. Consequently, PTEN deficiency led to dosage-dependent increases in phosphorylation and activation of Akt/protein kinase B, a well-characterized target of the phosphatidylinositol 3 kinase signaling pathway. Akt activation increased Bad phosphorylation and promoted Pten-/- cell survival. Our studies suggest that PTEN regulates the phosphatidylinositol 3,4, 5,-trisphosphate and Akt signaling pathway and consequently modulates two critical cellular processes: cell cycle progression and cell survival.

Electric field-induced suppression of PTEN drives epithelial-to-mesenchymal transition via mTORC1 activation.

PubMed

Yan, Tiantian; Jiang, Xupin; Guo, Xiaowei; Chen, Wen; Tang, Di; Zhang, Junhui; Zhang, Xingyue; Zhang, Dongxia; Zhang, Qiong; Jia, Jiezhi; Huang, Yuesheng

2017-02-01

Naturally occurring electric fields (EFs) are an intrinsic property of wounds. Endogenous EFs in skin wounds play critical roles in the dynamic and well-ordered biological process of wound healing. The epithelial-to-mesenchymal transition (EMT) allows keratinocytes to transition from sedentary cells to motile cells, facilitating wound healing. However, EMT-related studies have been performed without considering endogenous EFs. Thus, the relationship between electrical signals and the EMT remain elusive. Phosphatase and tension homolog (PTEN) and mammalian target of rapamycin complex 1 (mTORC1) are key molecules in sensing electrical cues, and they play significant roles in cellular responses to EFs. In addition, these molecules are closely related to the occurrence of the EMT in other cells. We used primary human keratinocytes to investigate the influence of EFs on the EMT as well as the roles of PTEN and mTORC1 in this process. The effects of EFs on the EMT were investigated by analyzing the levels of specific proteins and transcription factors. The roles of mTORC1 and PTEN and their relationship with each other were studied via pharmacological inhibition or genetic knockdown. A Zeiss imaging system and scratch assays were used to study single-cell motility and monolayer cell migration. EFs induced a range of both biochemical changes (e.g., increased Snail, Slug, vimentin, and N-cadherin expression, decreased E-cadherin expression) and functional changes (e.g., enhanced migratory capacity) that are characteristic of the EMT. EF-stimulated cells exhibited suppressed PTEN expression, and further PTEN downregulation led to the acquisition of more mesenchymal features and the loss of epithelial characteristics, which was accompanied by increased migratory capacity. PTEN overexpression reversed the EF-induced EMT and inhibited the migratory capacity of keratinocytes. EF-induced mTORC1 activation was a required component of the causal relationship between PTEN

Broad spectrum of neuropsychiatric phenotypes associated with white matter disease in PTEN hamartoma tumor syndrome.

PubMed

Balci, Tugce B; Davila, Jorge; Lewis, Denice; Boafo, Addo; Sell, Erick; Richer, Julie; Nikkel, Sarah M; Armour, Christine M; Tomiak, Eva; Lines, Matthew A; Sawyer, Sarah L

2018-01-01

White matter lesions have been described in patients with PTEN hamartoma tumor syndrome (PHTS). How these lesions correlate with the neurocognitive features associated with PTEN mutations, such as autism spectrum disorder (ASD) or developmental delay, has not been well established. We report nine patients with PTEN mutations and white matter changes on brain magnetic resonance imaging (MRI), eight of whom were referred for reasons other than developmental delay or ASD. Their clinical presentations ranged from asymptomatic macrocephaly with normal development/intellect, to obsessive compulsive disorder, and debilitating neurological disease. To our knowledge, this report constitutes the first detailed description of PTEN-related white matter changes in adult patients and in children with normal development and intelligence. We present a detailed assessment of the neuropsychological phenotype of our patients and discuss the relationship between the wide array of neuropsychiatric features and observed white matter findings in the context of these individuals. © 2017 Wiley Periodicals, Inc.

PTEN deficiency promotes macrophage infiltration and hypersensitivity of prostate cancer to IAP antagonist/radiation combination therapy

PubMed Central

Armstrong, Chris W.D.; Maxwell, Pamela J.; Ong, Chee Wee; Redmond, Kelly M.; McCann, Christopher; Neisen, Jessica; Ward, George A.; Chessari, Gianni; Johnson, Christopher; Crawford, Nyree T.; LaBonte, Melissa J.; Prise, Kevin M.; Robson, Tracy; Salto-Tellez, Manuel; Longley, Daniel B.; Waugh, David J.J.

2016-01-01

PTEN loss is prognostic for patient relapse post-radiotherapy in prostate cancer (CaP). Infiltration of tumor-associated macrophages (TAMs) is associated with reduced disease-free survival following radical prostatectomy. However, the association between PTEN loss, TAM infiltration and radiotherapy response of CaP cells remains to be evaluated. Immunohistochemical and molecular analysis of surgically-resected Gleason 7 tumors confirmed that PTEN loss correlated with increased CXCL8 expression and macrophage infiltration. However PTEN status had no discernable correlation with expression of other inflammatory markers by CaP cells, including TNF-α. In vitro, exposure to conditioned media harvested from irradiated PTEN null CaP cells induced chemotaxis of macrophage-like THP-1 cells, a response partially attenuated by CXCL8 inhibition. Co-culture with THP-1 cells resulted in a modest reduction in the radio-sensitivity of DU145 cells. Cytokine profiling revealed constitutive secretion of TNF-α from CaP cells irrespective of PTEN status and IR-induced TNF-α secretion from THP-1 cells. THP-1-derived TNF-α increased NFκB pro-survival activity and elevated expression of anti-apoptotic proteins including cellular inhibitor of apoptosis protein-1 (cIAP-1) in CaP cells, which could be attenuated by pre-treatment with a TNF-α neutralizing antibody. Treatment with a novel IAP antagonist, AT-IAP, decreased basal and TNF-α-induced cIAP-1 expression in CaP cells, switched TNF-α signaling from pro-survival to pro-apoptotic and increased radiation sensitivity of CaP cells in co-culture with THP-1 cells. We conclude that targeting cIAP-1 can overcome apoptosis resistance of CaP cells and is an ideal approach to exploit high TNF-α signals within the TAM-rich microenvironment of PTEN-deficient CaP cells to enhance response to radiotherapy. PMID:26799286

The role of the PTEN/AKT Pathway in NOTCH1-induced leukemia

PubMed Central

Palomero, Teresa; Dominguez, Maria; Ferrando, Adolfo A.

2008-01-01

Activating mutations in NOTCH1 are the most prominent genetic abnormality in T-cell acute Lymphoblastic Leukemia (T-ALL) and inhibition of NOTCH1 signaling with γ-secretase inhibitors (GSIs) has been proposed as targeted therapy in this disease. However, most T-ALL cell lines with mutations in NOTCH1 fail to respond to GSI therapy. Using gene expression profiling and mutation analysis we showed that mutational loss of PTEN is a common event in T-ALL and is associated with resistance to NOTCH inhibition. Furthermore, our studies revealed that NOTCH1 induces upregulation of the PI3K-AKT pathway via HES1, which negatively controls the expression of PTEN. This regulatory circuitry is evolutionary conserved from Drosophila to humans as demonstrated by the interaction of overexpression of Delta and Akt in a model of Notch-induced transformation in the fly eye. Loss of PTEN and constitutive activation of AKT in T-ALL induce increased glucose metabolism and bypass the requirement of NOTCH1 signaling to sustain cell growth. Importantly, PTEN-null/GSI resistant T-ALL cells switch their oncogene addiction from NOTCH1 to AKT and are highly sensitive to AKT inhibitors. These results should facilitate the development of molecular therapies targeting NOTCH1 and AKT for the treatment of T-ALL. PMID:18414037

The role of PTEN in regulation of hepatic macrophages activation and function in progression and reversal of liver fibrosis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cheng, Yahui; Tian, Yuanyao; Xia, Jialu

Activation of Kupffer cells (KCs) plays a pivotal role in the pathogenesis of liver fibrosis. The progression and reversal of CCl{sub 4}-induced mouse liver fibrosis showed a mixed induction of hepatic classical (M1) and alternative (M2) macrophage markers. Although the role of phosphatase and tensin homolog deleted on chromosome 10 (PTEN) in modulating myeloid cell activation has recently been identified, its function in macrophage activation during hepatic fibrosis remains to be fully appreciated. In our study, PTEN expression of KCs was remarkably decreased in CCl{sub 4}-induced mice but increased to a near-normal level in reversed mice. Moreover, PTEN was significantlymore » decreased in IL4-induced RAW 264.7 cells in vitro and lower expression of PTEN was observed in M2 macrophages in vivo. In addition, loss- and gain-of-function studies suggested that PTEN regulates M2 macrophages polarization via activation of PI3K/Akt/STAT6 signaling, but had a limited effect on M1 macrophages polarization in vitro. Additionally, Ly294002, a chemical inhibitor of PI3K/Akt, could dramatically down-regulate the hallmarks of M2 macrophages. In conclusion, PTEN mediates macrophages activation by PI3K/Akt/STAT6 signaling pathway, which provides novel compelling evidences on the potential of PTEN in liver injury and opens new cellular target for the pharmacological therapy of liver fibrosis. - Highlights: • CCl{sub 4} treatment triggered a mixed M1/M2 macrophage phenotype in fibrosis. • Lower expression of PTEN in murine M2 macrophages in vivo and vitro. • PTEN modulates M2 macrophages activation via PI3K/Akt/STAT6 signaling. • Provide a new cellular target modulate macrophage mediated hepatic fibrosis.« less

PTEN regulates p300-dependent hypoxia-inducible factor 1 transcriptional activity through Forkhead transcription factor 3a (FOXO3a)

PubMed Central

Emerling, Brooke M.; Weinberg, Frank; Liu, Juinn-Lin; Mak, Tak W.; Chandel, Navdeep S.

2008-01-01

The tumor suppressor PTEN is mutated or deleted in many tumors, causing the activation of the PI3K pathway. Here, we show that the loss of PTEN increases the transcriptional activity of hypoxia-inducible factor 1 (HIF-1) through the inactivation of Forkhead transcription factors (FOXO) in PTEN-null cells. Reintroduction of PTEN into the nucleus, overexpression of a nonphosphorylatable FOXO3a, which accumulates in the nucleus, or inhibition of nuclear export of FOXO3a by leptomycin B represses HIF-1 transcriptional activity in PTEN-null cells. HIF-1 transcriptional activity increases in PTEN-positive cells depleted of FOXO3a with siRNA. PTEN and FOXO3a regulate the transactivation domain of HIF-1α. Chromatin immunoprecipitation indicates that FOXO3a complexes with HIF-1α and p300 on the Glut-1 promoter, a HIF-1 target gene. Overexpression of p300 reverses FOXO3a-mediated repression of HIF-1 transcriptional activity. Coimmunoprecipitation and GAL4-HIF-1α transactivation assays reveal that FOXO3a interferes with p300-dependent HIF-1 transcriptional activity. Thus, FOXO3a negatively regulates HIF-1 transcriptional activity. PMID:18268343

Imaging heterogeneity in the mitochondrial redox state of premalignant pancreas in the pancreas-specific PTEN-null transgenic mouse model

PubMed Central

2013-01-01

Background Metabolic alteration is one of the hallmarks of carcinogenesis. We aimed to identify certain metabolic biomarkers for the early detection of pancreatic cancer (PC) using the transgenic PTEN-null mouse model. Pancreas-specific deletion of PTEN in mouse caused progressive premalignant lesions such as highly proliferative ductal metaplasia. We imaged the mitochondrial redox state of the pancreases of the transgenic mice approximately eight months old using the redox scanner, i.e., the nicotinamide adenine dinucleotide/oxidized flavoproteins (NADH/Fp) fluorescence imager at low temperature. Two different approaches, the global averaging of the redox indices without considering tissue heterogeneity along tissue depth and the univariate analysis of multi-section data using tissue depth as a covariate were adopted for the statistical analysis of the multi-section imaging data. The standard deviations of the redox indices and the histogram analysis with Gaussian fit were used to determine the tissue heterogeneity. Results All methods show consistently that the PTEN deficient pancreases (Pdx1-Cre;PTENlox/lox) were significantly more heterogeneous in their mitochondrial redox state compared to the controls (PTENlox/lox). Statistical analysis taking into account the variations of the redox state with tissue depth further shows that PTEN deletion significantly shifted the pancreatic tissue to an overall more oxidized state. Oxidization of the PTEN-null group was not seen when the imaging data were analyzed by global averaging without considering the variation of the redox indices along tissue depth, indicating the importance of taking tissue heterogeneity into account for the statistical analysis of the multi-section imaging data. Conclusions This study reveals a possible link between the mitochondrial redox state alteration of the pancreas and its malignant transformation and may be further developed for establishing potential metabolic biomarkers for the early

Developing a PTEN-ERG Signature to Improve Molecular Risk Stratification in Prostate Cancer

DTIC Science & Technology

2017-10-01

that there exist distinctive molecular correlates of PTEN loss in the context of ETS-negative versus ETS-positive human prostate cancers and that...distinctive molecular correlates of PTEN loss in the context of ETS-negative versus ETS-positive human PCa and that these may drive prognosis...and MSKCC cohort, correlate these data with gene expression data from the same cohort to confirm ETS status and enable full gene expression analyses of

Developing a PTEN-ERG Signature to Improve Molecular Risk Stratification in Prostate Cancer

DTIC Science & Technology

2017-10-01

SUPPLEMENTARY NOTES 14. ABSTRACT Prostate cancer (PCA) is a clinically and genetically heterogeneous and the development of a molecular classification is...AWARD NUMBER: W81XWH-16-1-0739 TITLE: Developing a PTEN-ERG Signature to Improve Molecular Risk Stratification in Prostate Cancer PRINCIPAL...AND SUBTITLE 5a. CONTRACT NUMBER Developing a PTEN-ERG Signature to Improve Molecular Risk Stratification in Prostate Cancer 5b. GRANT NUMBER W81XWH

Selective deletion of Pten in theca-interstitial cells leads to androgen excess and ovarian dysfunction in mice.

PubMed

Lan, Zi-Jian; Krause, M S; Redding, S D; Li, X; Wu, G Z; Zhou, H X; Bohler, H C; Ko, C; Cooney, A J; Zhou, Junmei; Lei, Z M

2017-03-15

Theca cell-selective Pten mutation (tPtenMT) in mice resulted in increases in PDK1 and Akt phosphorylation, indicating an over-activation of PI3K signaling in the ovaries. These mice displayed elevated androgen levels, ovary enlargement, antral follicle accumulation, early fertility loss and increased expression of Lhcgr and genes that are crucial to androgenesis. These abnormalities were partially reversed by treatments of PI3K or Akt inhibitor. LH actions in Pten deficient theca cells were potentiated. The phosphorylation of Foxo1 was increased, while the binding of Foxo1 to forkhead response elements in the Lhcgr promoter was reduced in tPtenMT theca cells, implying a mechanism by which PI3K/Akt-induced upregulation of Lhcgr in theca cells might be mediated by reducing the inhibitory effect of Foxo1 on the Lhcgr promoter. The phenotype of tPtenMT females is reminiscent of human PCOS and suggests that dysregulated PI3K cascade in theca cells may be involved in certain types of PCOS pathogenesis. Copyright © 2017 Elsevier B.V. All rights reserved.

Heterogeneity of PTEN and ERG expression in prostate cancer on core needle biopsies: implications for cancer risk stratification and biomarker sampling.

PubMed

Shah, Rajal B; Bentley, James; Jeffery, Zach; DeMarzo, Angelo M

2015-05-01

ERG and PTEN biomarkers are increasingly being analyzed on prostate core biopsies (NBXs); ERG as a marker of clonality and number of separately arising tumor foci and PTEN for prognostic information. Yet, in patients with multiple biopsy cores positive for cancer (PCa), there is no standardized approach for interrogation of these biomarkers in terms of the number of positive cores to evaluate. A total of 194 NBX cases containing more than one positive core with cancer were evaluated for ERG overexpression and PTEN loss by immunostaining (immunohistochemistry) of all positive cores. ERG overexpression or PTEN loss in at least one cancer core was present in 111 (57%) and 69 (36%) cases respectively. ERG overexpression was significantly associated with PTEN loss (P < .0001), and PTEN loss was associated with a high Gleason score (P < .0001). Inter- and intra-tumor core staining heterogeneity for ERG overexpression occurred in 42% and 5% cases and for PTEN loss both intra- and inter-tumor core heterogeneity was 68%. PTEN staining was highly discordant between PCa sites regardless of laterality. When the Gleason score was non-uniform across PCa sites, the combination of cores showing the highest Gleason score and largest tumor volume provided the best representation of ERG overexpression (92%) and PTEN loss (98%). When grades were uniform across cancer sites, the highest tumor volume core was generally representative of ERG overexpression (90%) but was less representative for PTEN loss (76%). Our results suggest that knowledge of this heterogeneity is critical for developing optimal yet cost-effective strategies to identify these underlying molecular abnormalities. Copyright © 2015 Elsevier Inc. All rights reserved.

PTEN loss represses glioblastoma tumor initiating cell differentiation via inactivation of Lgl1.

PubMed

Gont, Alexander; Hanson, Jennifer E L; Lavictoire, Sylvie J; Parolin, Doris A; Daneshmand, Manijeh; Restall, Ian J; Soucie, Mathieu; Nicholas, Garth; Woulfe, John; Kassam, Amin; Da Silva, Vasco F; Lorimer, Ian A J

2013-08-01

Glioblastoma multiforme is an aggressive and incurable type of brain tumor. A subset of undifferentiated glioblastoma cells, known as glioblastoma tumor initiating cells (GTICs), has an essential role in the malignancy of this disease and also appears to mediate resistance to radiation therapy and chemotherapy. GTICs retain the ability to differentiate into cells with reduced malignant potential, but the signaling pathways controlling differentiation are not fully understood at this time. PTEN loss is a very common in glioblastoma multiforme and leads to aberrant activation of the phosphoinositide 3-kinase pathway. Increased signalling through this pathway leads to activation of multiple protein kinases, including atypical protein kinase C. In Drosophila, active atypical protein kinase C has been shown to promote the self-renewal of neuroblasts, inhibiting their differentiation along a neuronal lineage. This effect is mediated by atypical protein kinase c-mediated phosphorylation and inactivation of Lgl, a protein that was first characterized as a tumour suppressor in Drosophila. The effects of the atypical protein kinase C/Lgl pathway on the differentiation status of GTICs, and its potential link to PTEN loss, have not been assessed previously. Here we show that PTEN loss leads to the phosphorylation and inactivation of Lgl by atypical protein kinase C in glioblastoma cells. Re-expression of PTEN in GTICs promoted their differentiation along a neuronal lineage. This effect was also seen when atypical protein kinase C was knocked down using RNA interference, and when a non-phosphorylatable, constitutively active form of Lgl was expressed in GTICs. Thus PTEN loss, acting via atypical protein kinase C activation and Lgl inactivation, helps to maintain GTICs in an undifferentiated state.

Withaferin A Inhibits Prostate Carcinogenesis in a PTEN-deficient Mouse Model of Prostate Cancer.

PubMed

Moselhy, Jim; Suman, Suman; Alghamdi, Mohammed; Chandarasekharan, Balaji; Das, Trinath P; Houda, Alatassi; Ankem, Murali; Damodaran, Chendil

2017-06-01

We recently demonstrated that AKT activation plays a role in prostate cancer progression and inhibits the pro-apoptotic function of FOXO3a and Par-4. AKT inhibition and Par-4 induction suppressed prostate cancer progression in preclinical models. Here, we investigate the chemopreventive effect of the phytonutrient Withaferin A (WA) on AKT-driven prostate tumorigenesis in a Pten conditional knockout (Pten-KO) mouse model of prostate cancer. Oral WA treatment was carried out at two different doses (3 and 5 mg/kg) and compared to vehicle over 45 weeks. Oral administration of WA for 45 weeks effectively inhibited primary tumor growth in comparison to vehicle controls. Pathological analysis showed the complete absence of metastatic lesions in organs from WA-treated mice, whereas discrete metastasis to the lungs was observed in control tumors. Immunohistochemical analysis revealed the down-regulation of pAKT expression and epithelial-to-mesenchymal transition markers, such as β-catenin and N-cadherin, in WA-treated tumors in comparison to controls. This result corroborates our previous findings from both cell culture and xenograft models of prostate cancer. Our findings demonstrate that the daily administration of a phytonutrient that targets AKT activation provides a safe and effective treatment for prostate cancer in a mouse model with strong potential for translation to human disease. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

Resveratrol regulates PTEN/Akt pathway through inhibition of MTA1/HDAC unit of the NuRD complex in prostate cancer.

PubMed

Dhar, Swati; Kumar, Avinash; Li, Kun; Tzivion, Guri; Levenson, Anait S

2015-02-01

Metastasis associated protein 1 (MTA1) is a component of the nucleosome remodeling and deacetylating (NuRD) complex which mediates gene silencing and is overexpressed in several cancers. We reported earlier that resveratrol, a dietary stilbene found in grapes, can down-regulate MTA1. In the present study, we show that PTEN is inactivated by MTA1 in prostate cancer cells. Further, we show that resveratrol promotes acetylation and reactivation of PTEN via inhibition of the MTA1/HDAC complex, resulting in inhibition of the Akt pathway. In addition, we show that MTA1 knockdown is sufficient to augment acetylation of PTEN indicating a crucial role of MTA1 itself in the regulation of PTEN acetylation contributing to its lipid phosphatase activity. Acetylated PTEN preferentially accumulates in the nucleus where it binds to MTA1. We also show that MTA1 interacts exclusively with PTEN acetylated on Lys¹²⁵ and Lys¹²⁸, resulting in diminished p-Akt levels. Finally, using orthotopic prostate cancer xenografts, we demonstrate that both resveratrol treatment and MTA1 knockdown enhance PTEN levels leading to a decreased p-Akt expression and proliferation index. Taken together, our results indicate that MTA1/HDAC unit is a negative regulator of PTEN which facilitates survival pathways and progression of prostate cancer and that resveratrol can reverse this process through its MTA1 inhibitory function. Copyright © 2014 Elsevier B.V. All rights reserved.

Targeted disruption of Pten in ovarian granulosa cells enhances ovulation and extends the life span of luteal cells.

PubMed

Fan, Heng-Yu; Liu, Zhilin; Cahill, Nicola; Richards, JoAnne S

2008-09-01

FSH activates the phosphatidylinositol-3 kinase (PI3K)/acute transforming retrovirus thymoma protein kinase pathway and thereby enhances granulosa cell differentiation in culture. To identify the physiological role of the PI3K pathway in vivo we disrupted the PI3K suppressor, Pten, in developing ovarian follicles. To selectively disrupt Pten expression in granulosa cells, Ptenfl/fl mice were mated with transgenic mice expressing cAMP response element recombinase driven by Cyp19 promoter (Cyp19-Cre). The resultant Pten mutant mice were fertile, ovulated more oocytes, and produced moderately more pups than control mice. These physiological differences in the Pten mutant mice were associated with hyperactivation of the PI3K/acute transforming retrovirus thymoma protein kinase pathway, decreased susceptibility to apoptosis, and increased proliferation of mutant granulosa cells. Strikingly, corpora lutea of the Pten mutant mice persisted longer than those of control mice. Although the follicular and luteal cell steroidogenesis in Ptenfl/fl;Cyp19-Cre mice was similar to controls, viable nonsteroidogenic luteal cells escaped structural luteolysis. These findings provide the novel evidence that Pten impacts the survival/life span of granulosa/luteal cells and that its loss not only results in the facilitated ovulation but also in the persistence of nonsteroidogenic luteal structures in the adult mouse ovary.

Induction of intrahepatic cholangiocellular carcinoma by liver-specific disruption of Smad4 and Pten in mice.

PubMed

Xu, Xiaoling; Kobayashi, Shogo; Qiao, Wenhui; Li, Cuiling; Xiao, Cuiying; Radaeva, Svetlana; Stiles, Bangyan; Wang, Rui-Hong; Ohara, Nobuya; Yoshino, Tadashi; LeRoith, Derek; Torbenson, Michael S; Gores, Gregory J; Wu, Hong; Gao, Bin; Deng, Chu-Xia

2006-07-01

Cholangiocellular carcinoma (CC), the second most common primary liver cancer, is associated with a poor prognosis. It has been shown that CCs harbor alterations of a number of tumor-suppressor genes and oncogenes, yet key regulators for tumorigenesis remain unknown. Here we have generated a mouse model that develops CC with high penetrance using liver-specific targeted disruption of tumor suppressors SMAD4 and PTEN. In the absence of SMAD4 and PTEN, hyperplastic foci emerge exclusively from bile ducts of mutant mice at 2 months of age and continue to grow, leading to tumor formation in all animals at 4-7 months of age. We show that CC formation follows a multistep progression of histopathological changes that are associated with significant alterations, including increased levels of phosphorylated AKT, FOXO1, GSK-3beta, mTOR, and ERK and increased nuclear levels of cyclin D1. We further demonstrate that SMAD4 and PTEN regulate each other through a novel feedback mechanism to maintain an expression balance and synergistically repress CC formation. Finally, our analysis of human CC detected PTEN inactivation in a majority of p-AKT-positive CCs, while about half also lost SMAD4 expression. These findings elucidate the relationship between SMAD4 and PTEN and extend our understanding of CC formation.

Simvastatin induces derepression of PTEN expression via NFkappaB to inhibit breast cancer cell growth.

PubMed

Ghosh-Choudhury, Nayana; Mandal, Chandi Charan; Ghosh-Choudhury, Nandini; Ghosh Choudhury, Goutam

2010-05-01

Sustained activation of Akt kinase acts as a focal regulator to increase cell growth and survival, which causes tumorigenesis including breast cancer. Statins, potent inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A reductase, display anticancer activity. The molecular mechanisms by which statins block cancer cell growth are poorly understood. We demonstrate that in the tumors derived from MDA-MB-231 human breast cancer cell xenografts, simvastatin significantly inhibited phosphorylation of Akt with concomitant attenuation of the expression of the anti-apoptotic protein Bcl(XL). In many cancer cells, Bcl(XL) is a target of NFkappaB. Simvastatin inhibited the DNA binding and transcriptional activities of NFkappaB resulting in marked reduction in transcription of Bcl(XL). Signals transmitted by anti-neoplastic mechanism implanted in the cancer cells serve to obstruct the initial outgrowth of tumors. One such mechanism represents the action of the tumor suppressor protein PTEN, which negatively regulates Akt kinase activity. We provide the first evidence for significantly increased levels of PTEN in the tumors of simvastatin-administered mice. Importantly, simvastatin markedly prevented binding of NFkappaB to the two canonical recognition elements, NFRE-1 and NFRE-2 present in the PTEN promoter. Contrary to the transcriptional suppression of Bcl(XL), simvastatin significantly increased the transcription of PTEN. Furthermore, expression of NFkappaB p65 subunit inhibited transcription of PTEN, resulting in reduced protein expression, which leads to enhanced phosphorylation of Akt. Taken together, our data present a novel bifaceted mechanism where simvastatin acts on a nodal transcription factor NFkappaB, which attenuates the expression of anti-apoptotic Bcl(XL) and simultaneously derepresses the expression of anti-proliferative/proapoptotic tumor suppressor PTEN to prevent breast cancer cell growth. Published by Elsevier Inc.

Four MicroRNAs Promote Prostate Cell Proliferation with Regulation of PTEN and Its Downstream Signals In Vitro

PubMed Central

Xue, Jing-lun; Chen, Jin-zhong

2013-01-01

Background Phosphatase and tensin homologue (PTEN), as a tumor suppressor, plays vital roles in tumorigenesis and progression of prostate cancer. However, the mechanisms of PTEN regulation still need further investigation. We here report that a combination of four microRNAs (miR-19b, miR-23b, miR-26a and miR-92a) promotes prostate cell proliferation by regulating PTEN and its downstream signals in vitro. Methodology/Principal Findings We found that the four microRNAs (miRNAs) could effectively suppress PTEN expression by directly interacting with its 3’ UTR in prostate epithelial and cancer cells. Under-expression of the four miRNAs by antisense neutralization up-regulates PTEN expression, while overexpression of the four miRNAs accelerates epithelial and prostate cancer cell proliferation. Furthermore, the expression of the four miRNAs could, singly or jointly, alter the expression of the key components in the phosphoinositide 3-kinase (PI3K)/Akt pathway, including PIK3CA, PIK3CD, PIK3R1 and Akt, along with their downstream signal, cyclin D1. Conclusions These results suggested that the four miRNAs could promote prostate cancer cell proliferation by co-regulating the expression of PTEN, PI3K/Akt pathway and cyclin D1 in vitro. These findings increase understanding of the molecular mechanisms of prostate carcinogenesis and progression, even provide valuable insights into the diagnosis, prognosis, and rational design of novel therapeutics for prostate cancer. PMID:24098737

Nuclear PTEN functions as an essential regulator of SRF-dependent transcription to control smooth muscle differentiation

PubMed Central

Horita, Henrick; Wysoczynski, Christina L.; Walker, Lori A.; Moulton, Karen S.; Li, Marcella; Ostriker, Allison; Tucker, Rebecca; McKinsey, Timothy A.; Churchill, Mair E. A.; Nemenoff, Raphael A.; Weiser-Evans, Mary C. M.

2016-01-01

Vascular disease progression is associated with marked changes in vascular smooth muscle cell (SMC) phenotype and function. SMC contractile gene expression and, thus differentiation, is under direct transcriptional control by the transcription factor, serum response factor (SRF); however, the mechanisms dynamically regulating SMC phenotype are not fully defined. Here we report that the lipid and protein phosphatase, PTEN, has a novel role in the nucleus by functioning as an indispensible regulator with SRF to maintain the differentiated SM phenotype. PTEN interacts with the N-terminal domain of SRF and PTEN–SRF interaction promotes SRF binding to essential promoter elements in SM-specific genes. Factors inducing phenotypic switching promote loss of nuclear PTEN through nucleo-cytoplasmic translocation resulting in reduced myogenically active SRF, but enhanced SRF activity on target genes involved in proliferation. Overall decreased expression of PTEN was observed in intimal SMCs of human atherosclerotic lesions underlying the potential clinical importance of these findings. PMID:26940659

Membrane association of the PTEN tumor suppressor: electrostatic interaction with phosphatidylserine-containing bilayers and regulatory role of the C-terminal tail.

PubMed

Shenoy, Siddharth S; Nanda, Hirsh; Lösche, Mathias

2012-12-01

The phosphatidylinositolphosphate phosphatase PTEN is the second most frequently mutated protein in human tumors. Its membrane association, allosteric activation and membrane dissociation are poorly understood. We recently reported PTEN binding affinities to membranes of different compositions (Shenoy et al., 2012, PLoS ONE 7, e32591) and a preliminary investigation of the protein-membrane complex with neutron reflectometry (NR). Here we use NR to validate molecular dynamics (MD) simulations of the protein and study conformational differences of the protein in solution and on anionic membranes. NR shows that full-length PTEN binds to such membranes roughly in the conformation and orientation suggested by the crystal structure of a truncated PTEN protein, in contrast with a recently presented model which suggested that membrane binding depends critically on the SUMOylation of the CBR3 loop of PTEN's C2 domain. Our MD simulations confirm that PTEN is peripherally bound to the bilayer surface and show slight differences of the protein structure in solution and in the membrane-bound state, where the protein body flattens against the bilayer surface. PTEN's C2 domain binds phosphatidylserine (PS) tightly through its CBR3 loop, and its phosphatase domain also forms electrostatic interactions with PS. NR and MD results show consistently that PTEN's unstructured, anionic C-terminal tail is repelled from the bilayer surface. In contrast, this tail is tightly tugged against the C2 domain in solution, partially obstructing the membrane-binding interface of the protein. Arresting the C-terminal tail in this conformation by phosphorylation may provide a control mechanism for PTEN's membrane binding and activity. Copyright © 2012 Elsevier Inc. All rights reserved.

PTEN loss promotes intratumoral androgen synthesis and tumor microenvironment remodeling via aberrant activation of RUNX2 in castration-resistant prostate cancer

PubMed Central

Yang, Yinhui; Bai, Yang; He, Yundong; Zhao, Yu; Chen, Jiaxiang; Ma, Linlin; Pan, Yunqian; Hinten, Michael; Zhang, Jun; Karnes, R. Jeffrey; Kohli, Manish; Westendorf, Jennifer J.; Li, Benyi; Zhu, Runzhi; Huang, Haojie; Xu, Wanhai

2018-01-01

Purpose Intratumoral androgen synthesis (IAS) is a key mechanism promoting androgen receptor (AR)reactivation and anti-androgen resistance in castration-resistant prostate cancer (CRPC). However, signaling pathways driving aberrant IAS remain poorly understood. Experimental Design The effect of components of the AKT-RUNX2-osteocalcin (OCN)-GPRC6A-CREB signaling axis on expression of steroidogenesis genes CYP11A1 and CYP17A1 and testosterone level were examined in PTEN-null human PCa cell lines. Pten knockout mice were employed to examine the effect of Runx2 heterozygous deletion or abiraterone acetate (ABA), a prodrug of the CYP17A1 inhibitor abiraterone on Cyp11a1 and Cyp17a1 expression, testosterone level and tumor microenvironment (TME) remodeling in vivo. Results We uncovered that activation of the AKT-RUNX2-OCN-GPRC6A-CREB signaling axis induced expression of CYP11A1 and CYP17A1 and testosterone production in PTEN-null PCa cell lines in culture. Deletion of Runx2 in Pten homozygous knockout prostate tumors decreased Cyp11a1 and Cyp17a1 expression, testosterone level and tumor growth in castrated mice. ABA treatment also inhibited testosterone synthesis and alleviated Pten loss-induced tumorigenesis in vivo. Pten deletion induced TME remodeling, but Runx2 heterozygous deletion or ABA treatment reversed the effect of Pten loss by decreasing expression of the collagenase Mmp9. Conclusions Abnormal RUNX2 activation plays a pivotal role in PTEN loss-induced IAS and TME remodeling, suggesting that the identified signaling cascade represents a viable target for effective treatment of PTEN-null PCa including CRPC. PMID:29167276

Combinatorial therapy with adenoviral-mediated PTEN and a PI3K inhibitor suppresses malignant glioma cell growth in vitro and in vivo by regulating the PI3K/AKT signaling pathway.

PubMed

Nan, Yang; Guo, Liyun; Song, Yunpeng; Wang, Le; Yu, Kai; Huang, Qiang; Zhong, Yue

2017-08-01

Glioblastoma is a highly invasive and challenging tumor of the central nervous system. The mutation/deletion of the tumor suppressor phosphatase and tensin homolog (PTEN) gene is the main genetic change identified in glioblastomas. PTEN plays a critical role in tumorigenesis and has been shown to be an important therapeutic target. The phosphatidylinositol 3-kinase (PI3K) inhibitor LY294002 is commonly used to inhibit glioma cell growth via regulation of the PI3K/AKT signaling pathway. In this study, we examined the growth inhibitory effects of a combinatorial therapy of adenoviral-mediated PTEN (Ad-PTEN) and LY294002 on LN229 and U251 glioma cells in vitro and on tumor xenografts in vivo. In vitro, LN229 and U251 glioma cells were treated by combinatorial therapy with Ad-PTEN and LY294002. The growth ability was determined by MTT assay. The cell cycle distribution was analyzed by flow cytometry. Cell invasive ability was analyzed by transwell invasion assay and cell apoptosis analysis via FITC-Annexin V analysis. In vivo, U251 subcutaneous glioblastoma xenograft was used to assay anti-tumor effect of combinatorial therapy with Ad-PTEN and LY294002 by mean volume of tumors, immunohistochemistry and TUNEL method. The combinatorial treatment clearly suppressed cell proliferation, arrested the cell cycle, reduced cell invasion and promoted cell apoptosis compared with the Ad-PTEN or LY294002 treatment alone. The treatment worked by inhibiting the PI3K/AKT pathway. In addition, the growth of U251 glioma xenografts treated with the combination of Ad-PTEN and LY294002 was significantly inhibited compared with those treated with Ad-PTEN or LY294002 alone. Our data indicated that the combination of Ad-PTEN and LY294002 effectively suppressed the malignant growth of human glioma cells in vitro and in tumor xenografts, suggesting a promising new approach for glioma gene therapy that warrants further investigation.

PTEN negatively regulates the cell lineage progression from NG2+ glial progenitor to oligodendrocyte via mTOR-independent signaling

PubMed Central

González-Fernández, Estibaliz; Jeong, Hey-Kyeong; Fukaya, Masahiro; Kim, Hyukmin; Khawaja, Rabia R; Srivastava, Isha N; Waisman, Ari; Son, Young-Jin

2018-01-01

Oligodendrocytes (OLs), the myelin-forming CNS glia, are highly vulnerable to cellular stresses, and a severe myelin loss underlies numerous CNS disorders. Expedited OL regeneration may prevent further axonal damage and facilitate functional CNS repair. Although adult OL progenitors (OPCs) are the primary players for OL regeneration, targetable OPC-specific intracellular signaling mechanisms for facilitated OL regeneration remain elusive. Here, we report that OPC-targeted PTEN inactivation in the mouse, in contrast to OL-specific manipulations, markedly promotes OL differentiation and regeneration in the mature CNS. Unexpectedly, an additional deletion of mTOR did not reverse the enhanced OL development from PTEN-deficient OPCs. Instead, ablation of GSK3β, another downstream signaling molecule that is negatively regulated by PTEN-Akt, enhanced OL development. Our results suggest that PTEN persistently suppresses OL development in an mTOR-independent manner, and at least in part, via controlling GSK3β activity. OPC-targeted PTEN-GSK3β inactivation may benefit facilitated OL regeneration and myelin repair. PMID:29461205

PTEN, a negative regulator of PI3K/Akt signaling, sustains brain stem cardiovascular regulation during mevinphos intoxication.

PubMed

Tsai, Ching-Yi; Wu, Jacqueline C C; Fang, Chi; Chang, Alice Y W

2017-09-01

Activation of PI3K/Akt signaling, leading to upregulation of nitric oxide synthase II (NOS II)/peroxynitrite cascade in the rostral ventrolateral medulla (RVLM), the brain stem site that maintains blood pressure and sympathetic vasomotor tone, underpins cardiovascular depression induced by the organophosphate pesticide mevinphos. By exhibiting dual-specificity protein- and lipid-phosphatase activity, phosphatase and tensin homolog (PTEN) directly antagonizes the PI3K/Akt signaling by dephosphorylation of phosphatidylinositol-3,4,5-trisphosphate, the lipid product of PI3K. Based on the guiding hypothesis that PTEN may sustain brain stem cardiovascular regulation during mevinphos intoxication as a negative regulator of PI3K/Akt signaling in the RVLM, we aimed in this study to clarify the mechanistic role of PTEN in mevinphos-induced circulatory depression. Microinjection bilaterally of mevinphos (10 nmol) into the RVLM of anesthetized Sprague-Dawley rats induced a progressive hypotension and a decrease in baroreflex-mediated sympathetic vasomotor tone. There was progressive augmentation in PTEN activity as reflected by a decrease in the oxidized form of PTEN in the RVLM during mevinhpos intoxication, without significant changes in the mRNA or protein level of PTEN. Loss-of-function manipulations of PTEN in the RVLM by immunoneutralization, pharmacological blockade or siRNA pretreatment significantly potentiated the increase in Akt activity or NOS II/peroxynitrite cascade in the RVLM, enhanced the elicited hypotension and exacerbated the already reduced baroreflex-mediated sympathetic vasomotor tone. We conclude that augmented PTEN activity via a decrease of its oxidized form in the RVLM sustains brain stem cardiovascular regulation during mevinphos intoxication via downregulation of the NOS II/peroxynitrite cascade as a negative regulator of PI3K/Akt signaling. Copyright © 2017 Elsevier Ltd. All rights reserved.

High frequency of loss of PTEN expression in human solid salivary adenoid cystic carcinoma and its implication for targeted therapy.

PubMed

Liu, Han; Du, Li; Wang, Ru; Wei, Chao; Liu, Bo; Zhu, Lei; Liu, Pixu; Liu, Qiang; Li, Jiang; Lu, Shi-Long; Xiao, Jing

2015-05-10

Salivary gland tumor (SGT) is one of the least studied cancers due to its rarity and heterogeneous histological types. Here, we reported that loss of PTEN expression was most frequently found in the poorly differentiated, high grade solid adenoid cystic carcinomas. Loss of PTEN expression correlated with activation of mTOR by increased phosphorylated S6 ribosome protein. We further functionally studied the role of PTEN in a pair of human SACC cell lines, SACC-83 and SACC-LM. Reduced PTEN level was correlated with the metastasis potential. When we knocked down PTEN in the SACC-83 cell line, we observed increased proliferation and enhanced migration/invasion in vitro, and increased tumor size in vivo. We further tested the therapeutical effect by applying a PI3K/mTOR inhibitor NVP-BEZ235 to both SACC cell lines. Decreased cell proliferation, increased apoptosis, as well as reduced cell migration/invasion were observed in both cell lines upon the NVP-BEZ235 treatment. Moreover, the NVP-BEZ235 treatment in a SGT xenograft mouse model significantly reduced primary tumor size and lung metastasis. Taken together, our results demonstrated that PTEN is a potent tumor suppressor in human SGTs, and targeting PI3K/mTOR pathway may be effective in the targeted therapy for human SGT patients with loss of PTEN expression.

Fractionated Ionizing Radiation Promotes Epithelial-Mesenchymal Transition in Human Esophageal Cancer Cells through PTEN Deficiency-Mediated Akt Activation.

PubMed

He, Enhui; Pan, Fei; Li, Guangchao; Li, Jingjing

2015-01-01

In some esophageal cancer patients, radiotherapy may not prevent distant metastasis thus resulting in poor survival. The underlying mechanism of metastasis in these patients is not well established. In this study, we have demonstrated that ionizing radiation may induce epithelial-mesenchymal transition (EMT) accompanied with increased cell migration and invasion, through downregulation of phosphatase and tensin homolog (PTEN), and activation of Akt/GSK-3β/Snail signaling. We developed a radioresistant (RR) esophageal squamous cancer cell line, KYSE-150/RR, by fractionated ionizing radiation (IR) treatment, and confirmed its radioresistance using a clonogenic survival assay. We found that the KYSE-150/RR cell line displayed typical morphological and molecular characteristics of EMT. In comparison to the parental cells, KYSE-150/RR cells showed an increase in post-IR colony survival, migration, and invasiveness. Furthermore, a decrease in PTEN in KYSE-150/RR cells was observed. We postulated that over-expression of PTEN may induce mesenchymal-epithelial transition in KYSE-150/RR cells and restore IR-induced increase of cell migration. Mechanistically, fractionated IR inhibits expression of PTEN, which leads to activation of Akt/GSK-3β signaling and is associated with the elevated levels of Snail protein, a transcription factor involved in EMT. Correspondingly, treatment with LY294002, a phosphatidylinositol-3-kinase inhibitor, mimicked PTEN overexpression effect in KYSE-150/RR cells, further suggesting a role for the Akt/GSK-3β/Snail signaling in effects mediated through PTEN. Together, these results strongly suggest that fractionated IR-mediated EMT in KYSE-150/RR cells is through PTEN-dependent pathways, highlighting a direct proinvasive effect of radiation treatment on tumor cells.

Loss of PTEN Expression Is Associated With High MicroRNA 24 Level and Poor Prognosis in Patients With Tongue Squamous Cell Carcinoma.

PubMed

Zhao, Jingzhu; Chi, Jiadong; Gao, Ming; Zhi, Jingtai; Li, Yigong; Zheng, Xiangqian

2017-07-01

The aim of this study was to detect the relationship between phosphatase and tensin homolog deletion on chromosome 10 (PTEN) and microRNA 24 (miR-24) and correlate PTEN expression with important clinical parameters of patients with tongue squamous cell carcinoma (TSCC). In this retrospective case series, all TSCC patients treated at Tianjin Medical University Cancer Institute and Hospital between March 2005 and October 2011 were retrospectively reviewed. Demographic information and clinical data (histologic type, clinical stage, tumor differentiation, and so on) were collected. The miR-24 level was detected by quantitative reverse transcription-polymerase chain reaction. The PTEN level was analyzed by immunohistochemistry and quantitative reverse transcription-polymerase chain reaction. Data analyses were performed by Spearman correlation analysis, Pearson χ 2 test, and paired t test. Kaplan-Meier curves, log-rank analyses, and a Cox proportional hazards model were used to evaluate the prognostic value of PTEN. A total of 90 patients (aged 59.4 ± 9.5 years, 53 men and 37 women) were identified. Loss of PTEN expression was detected in 28 of 90 tumors (31.1%). The PTEN messenger RNA level was negatively correlated with the miR-24 level (r = -0.569, P < .01). PTEN expression also was negatively correlated with the miR-24 level (r = -0.621, P < .01). Furthermore, PTEN expression was significantly lower in cancer tissues than in adjacent normal tissues, and its expression was negatively correlated with clinical stage (P < .01) and positively correlated with differentiation (P < .05) in TSCC patients. In addition, the Kaplan-Meier curve indicated that loss of PTEN expression resulted in poor survival of TSCC patients (P < .01). Multivariate analysis indicated that PTEN expression level and clinical stage may be independent prognostic factors for TSCC patients. This study suggested that PTEN expression was negatively correlated with the miR-24 level in

PTEN and PI-3 kinase inhibitors control LPS signaling and the lymphoproliferative response in the CD19+ B cell compartment

DOE Office of Scientific and Technical Information (OSTI.GOV)

Singh, Alok R.; Peirce, Susan K.; Joshi, Shweta

Pattern recognition receptors (PRRs), e.g. toll receptors (TLRs) that bind ligands within the microbiome have been implicated in the pathogenesis of cancer. LPS is a ligand for two TLR family members, TLR4 and RP105 which mediate LPS signaling in B cell proliferation and migration. Although LPS/TLR/RP105 signaling is well-studied; our understanding of the underlying molecular mechanisms controlling these PRR signaling pathways remains incomplete. Previous studies have demonstrated a role for PTEN/PI-3K signaling in B cell selection and survival, however a role for PTEN/PI-3K in TLR4/RP105/LPS signaling in the B cell compartment has not been reported. Herein, we crossed a CD19cremore » and PTEN{sup fl/fl} mouse to generate a conditional PTEN knockout mouse in the CD19+ B cell compartment. These mice were further crossed with an IL-14α transgenic mouse to study the combined effect of PTEN deletion, PI-3K inhibition and expression of IL-14α (a cytokine originally identified as a B cell growth factor) in CD19+ B cell lymphoproliferation and response to LPS stimulation. Targeted deletion of PTEN and directed expression of IL-14α in the CD19+ B cell compartment (IL-14+PTEN-/-) lead to marked splenomegaly and altered spleen morphology at baseline due to expansion of marginal zone B cells, a phenotype that was exaggerated by treatment with the B cell mitogen and TLR4/RP105 ligand, LPS. Moreover, LPS stimulation of CD19+ cells isolated from these mice display increased proliferation, augmented AKT and NFκB activation as well as increased expression of c-myc and cyclinD1. Interestingly, treatment of LPS treated IL-14+PTEN-/- mice with a pan PI-3K inhibitor, SF1126, reduced splenomegaly, cell proliferation, c-myc and cyclin D1 expression in the CD19+ B cell compartment and normalized the splenic histopathologic architecture. These findings provide the direct evidence that PTEN and PI-3K inhibitors control TLR4/RP105/LPS signaling in the CD19+ B cell compartment and that

Effect of mTOR Inhibitors in Nude Mice with Endometrial Carcinoma and Variable PTEN Expression Status

PubMed Central

Fong, Pedro; Meng, Li-rong

2014-01-01

Background The aim of this study was to investigate the sensitivity to rapamycin of endometrial cancer cells with different phosphatase and tensin homologue (PTEN) expression to understand the mechanism of resistance to mammalian target of rapamycin (mTOR) inhibitors in the treatment of endometrial cancer. Material/Methods Twenty specific pathogen-free female BALB/c mice received transplants of either HEC-1A (PTEN-positive) or Ishikawa (PTEN-negative) cells. Mice in the treatment group were injected intraperitoneally once a week for 4 consecutive weeks. The control group was injected weekly with phosphate buffer saline (PBS) for 4 consecutive weeks. Tumor volume, tumor mass, growth curves, and inhibition rate were measured, after which the mice were killed. Results Both tumor growth rate and size were slower in the treatment group than in the control group for all mice that received transplants of either HEC-1A or Ishikawa cells. The tumor inhibition rates in the treatment group were 48.1% and 67.1% in mice transplanted with HEC-1A and Ishikawa cells, respectively. Conclusions The inhibitory effects of rapamycin were enhanced in PTEN-negative Ishikawa tumor cells compared with PTEN-positive HEC-1A cells, which could explain the reduced effect of rapalogues in some endometrial cancer patients and help to understand the mechanism of resistance to this drug. PMID:25266877

Haploinsufficiency of the genes encoding the tumor suppressor Pten predisposes zebrafish to hemangiosarcoma.

PubMed

Choorapoikayil, Suma; Kuiper, Raoul V; de Bruin, Alain; den Hertog, Jeroen

2012-03-01

PTEN is an essential tumor suppressor that antagonizes Akt/PKB signaling. The zebrafish genome encodes two Pten genes, ptena and ptenb. Here, we report that zebrafish mutants that retain a single wild-type copy of ptena or ptenb (ptena(+/-)ptenb(-/-) or ptena(-/-)ptenb(+/-)) are viable and fertile. ptena(+/-)ptenb(-/-) fish develop tumors at a relatively high incidence (10.2%) and most tumors developed close to the eye (26/30). Histopathologically, the tumor masses were associated with the retrobulbar vascular network and diagnosed as hemangiosarcomas. A single tumor was identified in 42 ptena(-/-)ptenb(+/-) fish and was also diagnosed as hemangiosarcoma. Immunohistochemistry indicated that the tumor cells in ptena(+/-)ptenb(-/-) and ptena(-/-)ptenb(+/-) fish proliferated rapidly and were of endothelial origin. Akt/PKB signaling was activated in the tumors, whereas Ptena was still detected in tumor tissue from ptena(+/-)ptenb(-/-) zebrafish. We conclude that haploinsufficiency of the genes encoding Pten predisposes to hemangiosarcoma in zebrafish.

Exosomes promote cetuximab resistance via the PTEN/Akt pathway in colon cancer cells.

PubMed

Zhang, S; Zhang, Y; Qu, J; Che, X; Fan, Y; Hou, K; Guo, T; Deng, G; Song, N; Li, C; Wan, X; Qu, X; Liu, Y

2017-11-13

Cetuximab is widely used in patients with metastatic colon cancer expressing wildtype KRAS. However, acquired drug resistance limits its clinical efficacy. Exosomes are nanosized vesicles secreted by various cell types. Tumor cell-derived exosomes participate in many biological processes, including tumor invasion, metastasis, and drug resistance. In this study, exosomes derived from cetuximab-resistant RKO colon cancer cells induced cetuximab resistance in cetuximab-sensitive Caco-2 cells. Meanwhile, exosomes from RKO and Caco-2 cells showed different levels of phosphatase and tensin homolog (PTEN) and phosphor-Akt. Furthermore, reduced PTEN and increased phosphorylated Akt levels were found in Caco-2 cells after exposure to RKO cell-derived exosomes. Moreover, an Akt inhibitor prevented RKO cell-derived exosome-induced drug resistance in Caco-2 cells. These findings provide novel evidence that exosomes derived from cetuximab-resistant cells could induce cetuximab resistance in cetuximab-sensitive cells, by downregulating PTEN and increasing phosphorylated Akt levels.

PTENp1, a natural sponge of miR-21, mediates PTEN expression to inhibit the proliferation of oral squamous cell carcinoma.

PubMed

Gao, Ling; Ren, Wenhao; Zhang, Linmei; Li, Shaoming; Kong, Xinjuan; Zhang, Hao; Dong, Jianwei; Cai, Guangfeng; Jin, Changxiong; Zheng, Danqing; Zhi, Keqian

2017-04-01

PTENp1, non-coding RNA (ncRNA) pseudogene, is involved in oral squamous cell carcinoma (OSCC). The precise effects mediated by PTENp1 transcripts within intricate regulatory networks involving molecular interactions with ancestral gene PTEN and tumorigenicity in OSCC remain unclear. Here, we found that PTENp1 was aberrantly expressed in OSCC. There was a positive correlation between the expression levels of PTENp1 and PTEN. Further, we showed that PTENp1 acted as a competing endogenous RNA that protects PTEN transcripts from being inhibited by miR-21, and consequently inhibited proliferation and colony formation and triggered S-G2/M cell cycle arrest through the AKT pathway. Also, the homogeneous relationship between expression of PTENp1 and PTEN was confirmed in OSCC tumor xenografts. Finally, low expression of PTENp1 and PTEN was negatively associated with histological differentiation and OSCC prognosis. The present work provided the first evidence for the extraordinary crosstalk among PTENp1, PTEN, and miR-21, and rendered a new light on the treatment of OSCC. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Enhanced efficacy of AKT and FAK kinase combined inhibition in squamous cell lung carcinomas with stable reduction in PTEN

PubMed Central

Cavazzoni, Andrea; La Monica, Silvia; Alfieri, Roberta; Ravelli, Andrea; Van Der Steen, Nele; Sciarrillo, Rocco; Madeddu, Denise; Lagrasta, Costanza Anna Maria; Quaini, Federico; Bonelli, Mara; Fumarola, Claudia; Cretella, Daniele; Digiacomo, Graziana; Tiseo, Marcello; Peters, Godefridus J.; Ardizzoni, Andrea; Petronini, Pier Giorgio; Giovannetti, Elisa

2017-01-01

Squamous cell lung carcinoma (SCC) accounts for 30% of patients with NSCLC and to date, no molecular targeted agents are approved for this type of tumor. However, recent studies have revealed several oncogenic mutations in SCC patients, including an alteration of the PI3K/AKT pathway, i.e. PI3K point mutations and amplification, AKT mutations and loss or reduced PTEN expression. Prompted by our observation of a correlation between PTEN loss and FAK phosphorylation in a cohort of patients with stage IV SCC, we evaluated the relevance of PTEN loss in cancer progression as well as the efficacy of a new combined treatment with the pan PI3K inhibitor buparlisip and the FAK inhibitor defactinib. An increase in AKT and FAK phosphorylation, associated with increased proliferation and invasiveness, paralleled by the acquisition of mesenchymal markers, and overexpression of the oncomir miR-21 were observed in SKMES-1-derived cell clones with a stable reduction of PTEN. Notably, the combined treatment induced a synergistic inhibition of cell proliferation, and a significant reduction in cell migration and invasion only in cells with reduced PTEN. The molecular mechanisms underlying these findings were unraveled using a specific RTK array that showed a reduction in phosphorylation of key kinases such as JNK, GSK-3 α/β, and AMPK-α2, due to the concomitant decrease in AKT and FAK activation. In conclusion, the combination of buparlisib and defactinib was effective against cells with reduced PTEN and warrants further studies as a novel therapeutic strategy for stage IV SCC patients with loss of PTEN expression. PMID:28881794

Quantitative MRI establishes the efficacy of PI3K inhibitor (GDC-0941) multi-treatments in PTEN-deficient mice lymphoma.

PubMed

Wullschleger, Stephan; García-Martínez, Juan M; Duce, Suzanne L

2012-02-01

To assess the efficacy of multiple treatment of phosphatidylinositol-3-kinase (PI3K) inhibitor on autochthonous tumours in phosphatase and tensin homologue (Pten)-deficient genetically engineered mouse cancer models using a longitudinal magnetic resonance imaging (MRI) protocol. Using 3D MRI, B-cell follicular lymphoma growth was quantified in a Pten(+/-)Lkb1(+/hypo) mouse line, before, during and after repeated treatments with a PI3K inhibitor GDC-0941 (75 mg/kg). Mean pre-treatment linear tumour growth rate was 16.5±12.8 mm(3)/week. Repeated 28-day GDC-0941 administration, with 21 days 'off-treatment', induced average tumour regression of 41±7%. Upon cessation of the second treatment (which was not permanently cytocidal), tumours re-grew with an average linear growth rate of 40.1±15.5 mm(3)/week. There was no evidence of chemoresistance. This protocol can accommodate complex dosing schedules, as well as combine different cancer therapies. It reduces biological variability problems and resulted in a 10-fold reduction in mouse numbers compared with terminal assessment methods. It is ideal for preclinical efficacy studies and for phenotyping molecularly characterized mouse models when investigating gene function.

PTEN deletion and heme oxygenase-1 overexpression cooperate in prostate cancer progression and are associated with adverse clinical outcome.

PubMed

Li, Yunru; Su, Jie; DingZhang, Xiao; Zhang, Jianguo; Yoshimoto, Maisa; Liu, Shuhong; Bijian, Krikor; Gupta, Ajay; Squire, Jeremy A; Alaoui Jamali, Moulay A; Bismar, Tarek A

2011-05-01

Overexpression of the pro-survival protein heme oxygenase-1 (HO-1) and loss of the pro-apoptotic tumour suppressor PTEN are common events in prostate cancer (PCA). We assessed the occurrence of both HO-1 expression and PTEN deletion in two cohorts of men with localized and castration-resistant prostate cancer (CRPC). The phenotypic cooperation of these markers was examined in preclinical and clinical models. Overall, there was a statistically significant difference in HO-1 epithelial expression between benign, high-grade prostatic intraepithelial neoplasia (HGPIN), localized PCA, and CRPC (p < 0.0001). The highest epithelial HO-1 expression was noted in CRPC (2.00 ± 0.89), followed by benign prostate tissue (1.49 ± 1.03) (p = 0.0003), localized PCA (1.20 ± 0.95), and HGPIN (1.07 ± 0.87) (p < 0.0001). However, the difference between HGPIN and PCA was not statistically significant (p = 0.21). PTEN deletions were observed in 35/55 (63.6%) versus 68/183 (37.1%) cases of CRPC and localized PCA, respectively. Although neither HO-1 overexpression nor PTEN deletions alone in localized PCA showed a statistically significant association with PSA relapse, the combined status of both markers correlated with disease progression (log-rank test, p = 0.01). In a preclinical model, inhibition of HO-1 by shRNA in PTEN-deficient PC3M cell line and their matched cells where PTEN is restored strongly reduced cell growth and invasion in vitro and inhibited tumour growth and lung metastasis formation in mice compared to cells where only HO-1 is inhibited or PTEN is restored. In summary, we provide clinical and experimental evidence for cooperation between epithelial HO-1 expression and PTEN deletions in relation to the PCA patient's outcome. These findings could potentially lead to the discovery of novel therapeutic modalities for advanced PCA. Copyright © 2011 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Deletion of PTEN produces autism-like behavioral deficits and alterations in synaptic proteins.

PubMed

Lugo, Joaquin N; Smith, Gregory D; Arbuckle, Erin P; White, Jessika; Holley, Andrew J; Floruta, Crina M; Ahmed, Nowrin; Gomez, Maribel C; Okonkwo, Obi

2014-01-01

Many genes have been implicated in the underlying cause of autism but each gene accounts for only a small fraction of those diagnosed with autism. There is increasing evidence that activity-dependent changes in neuronal signaling could act as a convergent mechanism for many of the changes in synaptic proteins. One candidate signaling pathway that may have a critical role in autism is the PI3K/AKT/mTOR pathway. A major regulator of this pathway is the negative repressor phosphatase and tensin homolog (PTEN). In the current study we examined the behavioral and molecular consequences in mice with neuron subset-specific deletion of PTEN. The knockout (KO) mice showed deficits in social chamber and social partition test. KO mice demonstrated alterations in repetitive behavior, as measured in the marble burying test and hole-board test. They showed no changes in ultrasonic vocalizations emitted on postnatal day 10 or 12 compared to wildtype (WT) mice. They exhibited less anxiety in the elevated-plus maze test and were more active in the open field test compared to WT mice. In addition to the behavioral alterations, KO mice had elevation of phosphorylated AKT, phosphorylated S6, and an increase in S6K. KO mice had a decrease in mGluR but an increase in total and phosphorylated fragile X mental retardation protein. The disruptions in intracellular signaling may be why the KO mice had a decrease in the dendritic potassium channel Kv4.2 and a decrease in the synaptic scaffolding proteins PSD-95 and SAP102. These findings demonstrate that deletion of PTEN results in long-term alterations in social behavior, repetitive behavior, activity, and anxiety. In addition, deletion of PTEN significantly alters mGluR signaling and many synaptic proteins in the hippocampus. Our data demonstrates that deletion of PTEN can result in many of the behavioral features of autism and may provide insights into the regulation of intracellular signaling on synaptic proteins.

A multicenter study shows PTEN deletion is strongly associated with seminal vesicle involvement and extracapsular extension in localized prostate cancer.

PubMed

Troyer, Dean A; Jamaspishvili, Tamara; Wei, Wei; Feng, Ziding; Good, Jennifer; Hawley, Sarah; Fazli, Ladan; McKenney, Jesse K; Simko, Jeff; Hurtado-Coll, Antonio; Carroll, Peter R; Gleave, Martin; Lance, Raymond; Lin, Daniel W; Nelson, Peter S; Thompson, Ian M; True, Lawrence D; Brooks, James D; Squire, Jeremy A

2015-08-01

Loss of the phosphatase and tensin homolog (PTEN) tumor suppressor gene is a promising marker of aggressive prostate cancer. Active surveillance and watchful waiting are increasingly recommended to patients with small tumors felt to be low risk, highlighting the difficulties of Gleason scoring in this setting. There is an urgent need for predictive biomarkers that can be rapidly deployed to aid in clinical decision-making. Our objectives were to assess the incidence and ability of PTEN alterations to predict aggressive disease in a multicenter study. We used recently developed probes optimized for sensitivity and specificity in a four-color FISH deletion assay to study the Canary Retrospective multicenter Prostate Cancer Tissue Microarray (TMA). This TMA was constructed specifically for biomarker validation from radical prostatectomy specimens, and is accompanied by detailed clinical information with long-term follow-up. In 612 prostate cancers, the overall rate of PTEN deletion was 112 (18.3%). Hemizygous PTEN losses were present in 55/612 (9.0%) of cancers, whereas homozygous PTEN deletion was observed in 57/612 (9.3%) of tumors. Significant associations were found between PTEN status and pathologic stage (P < 0.0001), seminal vesicle invasion (P = 0.0008), extracapsular extension (P < 0.0001), and Gleason score (P = 0.0002). In logistic regression analysis of clinical and pathological variables, PTEN deletion was significantly associated with extracapsular extension, seminal vesicle involvement, and higher Gleason score. In the 406 patients in which clinical information was available, PTEN homozygous (P = 0.009) deletion was associated with worse post-operative recurrence-free survival (number of events = 189), pre-operative prostate specific antigen (PSA) (P < 0.001), and pathologic stage (P = 0.03). PTEN status assessed by FISH is an independent predictor for recurrence-free survival in multivariate models, as were seminal

A multicenter study shows PTEN deletion is strongly associated with seminal vesicle involvement and extracapsular extension in localized prostate cancer

PubMed Central

Troyer, Dean A; Jamaspishvili, Tamara; Wei, Wei; Feng, Ziding; Good, Jennifer; Hawley, Sarah; Fazli, Ladan; McKenney, Jesse K; Simko, Jeff; Hurtado-Coll, Antonio; Carroll, Peter R; Gleave, Martin; Lance, Raymond; Lin, Daniel W; Nelson, Peter S; Thompson, Ian M; True, Lawrence D; Brooks, James D; Squire, Jeremy A

2015-01-01

BACKGROUND Loss of the phosphatase and tensin homolog (PTEN) tumor suppressor gene is a promising marker of aggressive prostate cancer. Active surveillance and watchful waiting are increasingly recommended to patients with small tumors felt to be low risk, highlighting the difficulties of Gleason scoring in this setting. There is an urgent need for predictive biomarkers that can be rapidly deployed to aid in clinical decision-making. Our objectives were to assess the incidence and ability of PTEN alterations to predict aggressive disease in a multicenter study. METHODS We used recently developed probes optimized for sensitivity and specificity in a four-color FISH deletion assay to study the Canary Retrospective multicenter Prostate Cancer Tissue Microarray (TMA). This TMA was constructed specifically for biomarker validation from radical prostatectomy specimens, and is accompanied by detailed clinical information with long-term follow-up. RESULTS In 612 prostate cancers, the overall rate of PTEN deletion was 112 (18.3%). Hemizygous PTEN losses were present in 55/612 (9.0%) of cancers, whereas homozygous PTEN deletion was observed in 57/612 (9.3%) of tumors. Significant associations were found between PTEN status and pathologic stage (P < 0.0001), seminal vesicle invasion (P = 0.0008), extracapsular extension (P < 0.0001), and Gleason score (P = 0.0002). In logistic regression analysis of clinical and pathological variables, PTEN deletion was significantly associated with extracapsular extension, seminal vesicle involvement, and higher Gleason score. In the 406 patients in which clinical information was available, PTEN homozygous (P = 0.009) deletion was associated with worse post-operative recurrence-free survival (number of events = 189), pre-operative prostate specific antigen (PSA) (P < 0.001), and pathologic stage (P = 0.03). CONCLUSION PTEN status assessed by FISH is an independent predictor for recurrence-free survival in

Variable laterality of corticospinal tract axons that regenerate after spinal cord injury as a result of PTEN deletion or knock-down

PubMed Central

Willenberg, Rafer; Zukor, Katherine; Liu, Kai; He, Zhigang; Steward, Oswald

2016-01-01

Corticospinal tract (CST) axons from one hemisphere normally extend and terminate predominantly in the contralateral spinal cord. We previously showed that deleting PTEN in the sensorimotor cortex enables CST axons to regenerate after spinal cord injury and that some regenerating axons extend along the “wrong” side. Here, we characterize the degree of specificity of regrowth in terms of laterality. PTEN was selectively deleted via cortical AAV-Cre injections in neonatal PTEN-floxed mice. As adults, mice received dorsal hemisection injuries at T12 or complete crush injuries at T9. CST axons from one hemisphere were traced by unilateral BDA injections in PTEN-deleted mice with spinal cord injury and in non-injured PTEN-floxed mice that had not received AAV-Cre. In non-injured mice, 97.9 ± 0.7% of BDA-labeled axons in white matter and 88.5 ± 1.0% of BDA-labeled axons in grey matter were contralateral to the cortex of origin. In contrast, laterality of CST axons that extended past a lesion due to PTEN deletion varied across animals. In some cases, regenerated axons extended predominantly on the ipsilateral side, in other cases, axons extended predominantly contralaterally, and in others, axons were similar in numbers on both sides. Similar results were seen in analyses of cases from previous studies using shRNA-mediated PTEN knock-down. These results indicate that CST axons that extend past a lesion due to PTEN deletion or knock-down do not maintain the contralateral rule of the non-injured CST, highlighting one aspect for how resultant circuitry from regenerating axons may differ from that of the uninjured CST. PMID:26878190

Anticancer effect of curcumin inhibits cell growth through miR-21/PTEN/Akt pathway in breast cancer cell.

PubMed

Wang, Xinzheng; Hang, Yakai; Liu, Jinbiao; Hou, Yongqiang; Wang, Ning; Wang, Mingjun

2017-06-01

Curcumin is a polyphenol extracted from turmeric, which that belongs to the Zingiberaceae family. Curcumin has numerous effects, including anti-inflammatory, antitumor, anti-oxidative and antimicrobial effects. However, the effects of curcumin on human breast cancer cells remain largely unknown. The aim of the present study was to investigate the anticancer effects and the mechanisms by which curcumin affects breast cancer cells. The anticancer effect of curcumin on cell viability and cytotoxicity on human breast cancer MCF-7 cells was analyzed using 3-(4,5-dimethyl-2-thiazolyl)-2, 5-diphenyl-2H-tetrazolium bromide and lactate dehydrogenase assays, respectively. Cell apoptosis of MCF-7 cells was detected using flow cytometry, 4',6-diamidino-2-phenylindolestaining assay and caspase-3/9 activity kits. Reverse transcription-quantitative polymerase chain reaction was used to analyze microRNA-21 (miR-21) expression in MCF-7 cells. The protein expression of phosphatase and tensin homolog (PTEN) and phospho-protein kinase B (pAkt) was determined by western blot analysis. miR-21 was transfected into MCF-7 cells and the anticancer effect of curcumin on cell viability and the expression of PTEN and pAkt was analyzed. The present results demonstrated that curcumin inhibited cell viability and induced cytotoxicity of MCF-7 cells in a concentration- and time-dependent manner, by inducing apoptosis and increasing caspase-3/9 activities. In addition, curcumin downregulated miR-21 expression in MCF-7 cells by upregulating the PTEN/Akt signaling pathway. The present study has for the first time, to the best of our knowledge, revealed the anticancer effect of curcumin in suppressing breast cancer cell growth, and has elucidated that the miR-21/PTEN/Akt signaling pathway is a key mechanism for the anticancer effects of curcumin.

Haploinsufficiency of the genes encoding the tumor suppressor Pten predisposes zebrafish to hemangiosarcoma

PubMed Central

Choorapoikayil, Suma; Kuiper, Raoul V.; de Bruin, Alain; den Hertog, Jeroen

2012-01-01

SUMMARY PTEN is an essential tumor suppressor that antagonizes Akt/PKB signaling. The zebrafish genome encodes two Pten genes, ptena and ptenb. Here, we report that zebrafish mutants that retain a single wild-type copy of ptena or ptenb (ptena+/−ptenb−/− or ptena−/−ptenb+/−) are viable and fertile. ptena+/−ptenb−/− fish develop tumors at a relatively high incidence (10.2%) and most tumors developed close to the eye (26/30). Histopathologically, the tumor masses were associated with the retrobulbar vascular network and diagnosed as hemangiosarcomas. A single tumor was identified in 42 ptena−/−ptenb+/− fish and was also diagnosed as hemangiosarcoma. Immunohistochemistry indicated that the tumor cells in ptena+/−ptenb−/− and ptena−/−ptenb+/− fish proliferated rapidly and were of endothelial origin. Akt/PKB signaling was activated in the tumors, whereas Ptena was still detected in tumor tissue from ptena+/−ptenb−/− zebrafish. We conclude that haploinsufficiency of the genes encoding Pten predisposes to hemangiosarcoma in zebrafish. PMID:22071262

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

DOE Office of Scientific and Technical Information (OSTI.GOV)

Guo, Pin; Nie, Quanmin; Lan, Jin

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),more » 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.« less

MC1R is a Potent Regulator of PTEN after UV Exposure in Melanocytes

PubMed Central

Cao, Juxiang; Wan, Lixin; Hacker, Elke; Dai, Xiangpeng; Lenna, Stefania; Jimenez-Cervantes, Celia; Wang, Yongjun; Leslie, Nick R.; Xu, George X.; Widlund, Hans R.; Ryu, Byungwoo; Alani, Rhoda M.; Dutton-Regester, Ken; Goding, Colin R.; Hayward, Nicholas K.; Wei, Wenyi; Cui, Rutao

2013-01-01

Summary The individuals carrying melanocortin-1-receptor (MC1R) variants, especially those associated with red hair color, fair skin and poor tanning ability (RHC-trait), are more prone to melanoma while the underlying mechanism is poorly defined. Here, we report that UVB exposure triggers PTEN interaction with wild-type (WT), but not RHC-associated MC1R variants, which protects PTEN from WWP2-mediated degradation, leading to AKT inactivation. Strikingly, the biological consequences of the failure of MC1R variants to suppress PI3K/AKT signaling are highly context dependent. In primary melanocytes, hyperactivation of PI3K/AKT signaling leads to premature senescence; in the presence of BRAFV600E, MC1R deficiency-induced elevated PI3K/AKT signaling drives oncogenic transformation. These studies establish the MC1R-PTEN axis as a central regulator for melanocytes’ response to UVB exposure, and reveal the molecular basis underlying the association between MC1R variants and melanomagenesis. PMID:23973372

Synergistic function of Smad4 and PTEN in suppressing forestomach squamous cell carcinoma in the mouse.

PubMed

Teng, Yan; Sun, An-Na; Pan, Xiao-Chen; Yang, Guan; Yang, Lei-Lei; Wang, Ming-Rong; Yang, Xiao

2006-07-15

The genetic bases underlying esophageal tumorigenesis are poorly understood. Our previous studies have shown that coordinated deletion of the Smad4 and PTEN genes results in accelerated hair loss and skin tumor formation in mice. Herein, we exemplify that the concomitant inactivation of Smad4 and PTEN accelerates spontaneous forestomach carcinogenesis at complete penetrance during the first 2 months of age. All of the forestomach tumors were invasive squamous cell carcinomas (SCCs), which recapitulated the natural history and pathologic features of human esophageal SCCs. A small population of the SCC lesions was accompanied by adenocarcinomas at the adjacent submucosa region in the double mutant mice. The rapid progression of forestomach tumor formation in the Smad4 and PTEN double knockout mice corresponded to a dramatic increase in esophageal and forestomach epithelial proliferation. The decreased expression of p27, p21, and p16 together with the overexpression of cyclin D1 contributed cooperatively to the accelerated forestomach tumorigenesis in the double mutant mice. Our results point strongly to the crucial relevance of synergy between Smad4 and PTEN to suppress forestomach tumorigenesis through the cooperative induction of cell cycle inhibitors.

Gene Expression and Correlation of Pten and Fabp4 in Liver, Muscle, and Adipose Tissues of Type 2 Diabetes Rats.

PubMed

Su, Di; Zhang, Chuan-Ling; Gao, Ying-Chun; Liu, Xiao-Ying; Li, Cai-Ping; Huangfu, Jian; Xiao, Rui

2015-11-22

The aim of this work was to study the Fabp4 and Pten gene expression and correlation in the liver, muscle, and adipose tissues of type 2 diabetes mellitus (T2DM) rats. Male Wistar rats (8 weeks old) were randomly divided into 2 groups (n=12/group): a control group fed a normal diet for 8 weeks and an experimental group fed a high-fat, high-sugar diet for 8 weeks and that received 25 mg/kg streptozotocin by intraperitoneal injection to induce T2DM. The random blood glucose, fasting blood glucose, and fasting insulin levels were measured. The expression of Pten and Fabp4 in the liver, muscle, and epididymal adipose tissues was estimated by real-time quantitative PCR. Pearson correlation coefficient analysis was used to investigate the expression correlation between Pten and Fabp4 in T2DM rats. The gene expressions of Pten and Fabp4 in the liver, muscle, and adipose tissues of T2DM rats were all significantly higher than those in the control group (P<0.05). Pten was highly expressed in the muscles and Fabp4 was highly expressed in muscle and adipose tissues. Furthermore, expressions of Fabp4 and Pten in the muscle and adipose tissues of T2DM rats were positively correlated (P<0.05), but not in the liver. The increased expression of PTEN and FABP4 in the adipose and muscles of T2DM rats may play an important role in the insulin resistance of T2DM. However, the mechanism by which these 2 genes function in T2DM needs further study.

TGF-β1 stimulates migration of type II endometrial cancer cells by down-regulating PTEN via activation of SMAD and ERK1/2 signaling pathways.

PubMed

Xiong, Siyuan; Cheng, Jung-Chien; Klausen, Christian; Zhao, Jianfang; Leung, Peter C K

2016-09-20

PTEN acts as a tumor suppressor primarily by antagonizing the PI3K/AKT signaling pathway. PTEN is frequently mutated in human cancers; however, in type II endometrial cancers its mutation rate is very low. Overexpression of TGF-β1 and its receptors has been reported to correlate with metastasis of human cancers and reduced survival rates. Although TGF-β1 has been shown to regulate PTEN expression through various mechanisms, it is not yet known if the same is true in type II endometrial cancer. In the present study, we show that treatment with TGF-β1 stimulates the migration of two type II endometrial cancer cell lines, KLE and HEC-50. In addition, TGF-β1 treatment down-regulates both mRNA and protein levels of PTEN. Overexpression of PTEN or inhibition of PI3K abolishes TGF-β1-stimulated cell migration. TGF-β1 induces SMAD2/3 phosphorylation and knockdown of common SMAD4 inhibits the suppressive effects of TGF-β1 on PTEN mRNA and protein. Interestingly, TGF-β1 induces ERK1/2 phosphorylation and pre-treatment with a MEK inhibitor attenuates the suppression of PTEN protein, but not mRNA, by TGF-β1. This study provides important insights into the molecular mechanisms mediating TGF-β1-induced down-regulation of PTEN and demonstrates an important role of PTEN in the regulation of type II endometrial cancer cell migration.

TGF-β1 stimulates migration of type II endometrial cancer cells by down-regulating PTEN via activation of SMAD and ERK1/2 signaling pathways

PubMed Central

Xiong, Siyuan; Cheng, Jung-Chien; Klausen, Christian; Zhao, Jianfang; Leung, Peter C.K.

2016-01-01

PTEN acts as a tumor suppressor primarily by antagonizing the PI3K/AKT signaling pathway. PTEN is frequently mutated in human cancers; however, in type II endometrial cancers its mutation rate is very low. Overexpression of TGF-β1 and its receptors has been reported to correlate with metastasis of human cancers and reduced survival rates. Although TGF-β1 has been shown to regulate PTEN expression through various mechanisms, it is not yet known if the same is true in type II endometrial cancer. In the present study, we show that treatment with TGF-β1 stimulates the migration of two type II endometrial cancer cell lines, KLE and HEC-50. In addition, TGF-β1 treatment down-regulates both mRNA and protein levels of PTEN. Overexpression of PTEN or inhibition of PI3K abolishes TGF-β1-stimulated cell migration. TGF-β1 induces SMAD2/3 phosphorylation and knockdown of common SMAD4 inhibits the suppressive effects of TGF-β1 on PTEN mRNA and protein. Interestingly, TGF-β1 induces ERK1/2 phosphorylation and pre-treatment with a MEK inhibitor attenuates the suppression of PTEN protein, but not mRNA, by TGF-β1. This study provides important insights into the molecular mechanisms mediating TGF-β1-induced down-regulation of PTEN and demonstrates an important role of PTEN in the regulation of type II endometrial cancer cell migration. PMID:27542208

Autism-epilepsy phenotype with macrocephaly suggests PTEN, but not GLIALCAM, genetic screening.

PubMed

Marchese, Maria; Conti, Valerio; Valvo, Giulia; Moro, Francesca; Muratori, Filippo; Tancredi, Raffaella; Santorelli, Filippo M; Guerrini, Renzo; Sicca, Federico

2014-02-27

With a complex and extremely high clinical and genetic heterogeneity, autism spectrum disorders (ASD) are better dissected if one takes into account specific endophenotypes. Comorbidity of ASD with epilepsy (or paroxysmal EEG) has long been described and seems to have strong genetic background. Macrocephaly also represents a well-known endophenotype in subgroups of ASD individuals, which suggests pathogenic mechanisms accelerating brain growth in early development and predisposing to the disorder. We attempted to estimate the association of gene variants with neurodevelopmental disorders in patients with autism-epilepsy phenotype (AEP) and cranial overgrowth, analyzing two genes previously reported to be associated with autism and macrocephaly. We analyzed the coding sequences and exon-intron boundaries of GLIALCAM, encoding an IgG-like cell adhesion protein, in 81 individuals with Autism Spectrum Disorders, either with or without comorbid epilepsy, paroxysmal EEG and/or macrocephaly, and the PTEN gene in the subsample with macrocephaly. Among 81 individuals with ASD, 31 had concurrent macrocephaly. Head circumference, moreover, was over the 99.7th percentile ("extreme" macrocephaly) in 6/31 (19%) patients. Whilst we detected in GLIALCAM several single nucleotide variants without clear pathogenic effects, we found a novel PTEN heterozygous frameshift mutation in one case with "extreme" macrocephaly, autism, intellectual disability and seizures. We did not find a clear association between GLIALCAM mutations and AEP-macrocephaly comorbidity. The identification of a novel frameshift variant of PTEN in a patient with "extreme" macrocephaly, autism, intellectual disability and seizures, confirms this gene as a major candidate in the ASD-macrocephaly endophenotype. The concurrence of epilepsy in the same patient also suggests that PTEN, and the downstream signaling pathway, might deserve to be investigated in autism-epilepsy comorbidity. Working on clinical

PTEN/MMAC1 Mutations in Hepatocellular Carcinomas: Somatic Inactivation of Both Alleles in Tumors

PubMed Central

Kawamura, Naoki; Nagai, Hisaki; Bando, Koichi; Koyama, Masaaki; Matsumoto, Satoshi; Tajiri, Takashi; Onda, Masahiko; Fujimoto, Jiro; Ueki, Takahiro; Konishi, Noboru; Shiba, Tadayoshi

1999-01-01

Allelic loss of loci on chromosome 10q occurs frequently in hepatocellular carcinomas. Somatic mutations of the PTEN/MMAC1 gene on this chromosome at 10q23 were recently identified in sporadic cancers of the uterus, brain, prostate and breast. To investigate the potential role of PTEN/MMAC1 gene in the genesis of hepatocellular carcinomas, we examined 96 tumors for allelic loss on 10q and also for subtle mutations anywhere within the coding region of PTEN/MMAC1 gene. Allelic loss was identified in 25 of the 89 (27%) tumors that were informative for polymorphic markers in the region. Somatic mutations were identified in five of those tumors: three frameshift mutations, a 1‐bp insertion at codon 83–84 in exon 4 and two 4‐bp deletions, both at codon 318–319 in exon 8; two C‐to‐G transversion mutation, both at ‐9 bp from the initiation codon in the 5’non‐coding region of exon 1. No missense mutation was observed in this panel of tumors. In most of the informative tumors carrying intragenic mutations of one allele, we were able to detect loss of heterozygosity as well. These findings suggest that two alleles of the PTEN/MMAC1 gene may be inactivated by a combination of intragenic point mutation on one allele and loss of chromosomal material on the other allele in some of these tumors. PMID:10363579

Loss of mTOR repressors Tsc1 or Pten has divergent effects on excitatory and inhibitory synaptic transmission in single hippocampal neuron cultures.

PubMed

Weston, Matthew C; Chen, Hongmei; Swann, John W

2014-01-01

The Pten and Tsc1 genes both encode proteins that repress mechanistic target of rapamycin (mTOR) signaling. Disruption of either gene in the brain results in epilepsy and autism-like symptoms in humans and mouse models, therefore it is important to understand the molecular and physiological events that lead from gene disruption to disease phenotypes. Given the similar roles these two molecules play in the regulation of cellular growth and the overlap in the phenotypes that result from their loss, we predicted that the deletion of either the Pten or Tsc1 gene from autaptic hippocampal neurons would have similar effects on neuronal morphology and synaptic transmission. Accordingly, we found that loss of either Pten or Tsc1 caused comparable increases in soma size, dendrite length and action potential properties. However, the effects of Pten and Tsc1 loss on synaptic transmission were different. Loss of Pten lead to an increase in both excitatory and inhibitory neurotransmission, while loss of Tsc1 did not affect excitatory neurotransmission and reduced inhibitory transmission by decreasing mIPSC amplitude. Although the loss of Pten or Tsc1 both increased downstream mTORC1 signaling, phosphorylation of Akt was increased in Pten-ko and decreased in Tsc1-ko neurons, potentially accounting for the different effects on synaptic transmission. Despite the different effects at the synaptic level, our data suggest that loss of Pten or Tsc1 may both lead to an increase in the ratio of excitation to inhibition at the network level, an effect that has been proposed to underlie both epilepsy and autism.

Neuroprotection by baicalein in ischemic brain injury involves PTEN/AKT pathway.

PubMed

Liu, Chao; Wu, Jiliang; Xu, Kui; Cai, Fei; Gu, Jun; Ma, Liqun; Chen, Jianguo

2010-03-01

Recently more evidences support baicalein (Bai) is neuroprotective in models of ischemic stroke. This study was conducted to determine the molecular mechanisms involved in this effect. Either permanent or transient (2 h) middle cerebral artery occlusion (MCAO) was induced in rats in this study. Permanent MCAO led to larger infarct volumes in contrast to transient MCAO. Only in transient MCAO, Bai administration significantly reduced infarct size. Baicalein also markedly reduced apoptosis in the penumbra of transient MCAO rats. Additionally, oxygen and glucose deprivation (OGD) was used to mimic ischemic insult in primary cultured cortical neurons. A rapid increase in the intracellular reactive oxygen species level and nitrotyrosine formation induced by OGD was counteracted by Bai, which is parallel with attenuated cell injury. The reduction of phosphorylation Akt and glycogen synthase kinase-3beta (GSK3beta) induced by OGD was restored by Bai, which was associated with preserved levels of phosphorylation of PTEN, the phophatase that negatively regulates Akt. As a consequence, Bcl-2/Bcl-xL-associated death protein phosphorylation was increased and the protein level of Bcl-2 in motochondria was maintained, which subsequently antagonize cytochrome c released in cytosol. LY294002 blocked the increase in phospho-AKT evoked by Bai and abolished the associated protective effect. Together, these findings provide evidence that Bai protects neurons against ischemia injury and this neuroprotective effect involves PI3K/Akt and PTEN pathway.

Identification of a PTEN mutation with reduced protein stability, phosphatase activity, and nuclear localization in Hong Kong patients with autistic features, neurodevelopmental delays, and macrocephaly.

PubMed

Wong, Chi Wai; Or, Penelope Mei Yu; Wang, Yubing; Li, Lisha; Li, Jing; Yan, Mingfei; Cao, Ye; Luk, Ho Ming; Tong, Tony Ming For; Leslie, Nick R; Lo, Ivan Fai-Man; Choy, Kwong Wai; Chan, Andrew Man Lok

2018-04-02

PTEN is a tumor suppressor gene inactivated in over 30% of human cancers. It encodes a lipid phosphatase that serves as a gatekeeper of the phosphoinositide 3-kinase signaling pathway. Germline mutation frequently occurs in this gene in patients diagnosed with PTEN Hamartoma Tumor Syndrome (PHTS). PHTS individuals are characterized by macrocephaly, benign growth of multiple tissues and increased tumor risk. In addition, autistic phenotypes are found in 10-20% of individuals carrying the germline PTEN mutation with macrocephaly. In this report, 13 suspected PHTS patients were screened for mutation in the PTEN gene. A missense variant (c. 302T > C) substituting the isoleucine at codon 101 to a threonine, a single nucleotide insertion (c. 327-328insC) causing a frame shift mutation and termination at codon 109, and a nonsense variant (c. 1003C > T) truncated the protein at codon 335 were identified. The I101T mutation significantly reduced PTEN protein expression levels by 2.5- to 4.0-fold. Mechanistically, I101T reduced the protein half-life of PTEN possibly due to enhanced polyubiquitination at Lysine 13. However, the I101T mutant retained almost 30% of the lipid phosphatase activity of the wild-type protein. Finally, the I101T mutant has reduced phosphorylation at a PTEN auto-dephosphorylation site at Threonine 366 and a lowered ratio of nuclear to cytosolic protein level. These partial losses of multiple PTEN biochemical functions may contribute to the tissue overgrowth and autistic features of this PHTS patient. Autism Res 2018. © 2018 The Authors Autism Research published by International Society for Autism Research and Wiley Periodicals, Inc. The genetics of autism spectrum disorders is highly complex with individual risk influenced by both genetic and environmental factors. Mutation in the human PTEN gene confers a high risk of developing autistic behavior. This report revealed that PTEN mutations occurred in 23% of a selected group of Hong Kong

Prognostic impact of gastrointestinal bleeding and expression of PTEN and Ki-67 on primary gastrointestinal stromal tumors

PubMed Central

2014-01-01

Background Prognostic indicators for gastrointestinal stromal tumors (GISTs) are under investigation. The latest risk classification criteria may still have room for improvement. This study aims to investigate prognostic factors for primary GISTs from three aspects, including clinicopathological parameters, immunohistochemical (IHC) expression of PTEN, and Ki-67 labeling index (LI), and attempts to find valuable predictors for the malignancy potential of primary GISTs. Methods Tumor samples and clinicopathological data from 84 patients with primary GISTs after R0 resection were obtained. Immunohistochemical analysis was performed based on tissue microarray (TMA) to estimate expression of PTEN and Ki-67 in tumor cells. Results The cut-off point of Ki-67 LI was determined as 1%, using a receiver operator characteristic test with a sensitivity of 71.7% and a specificity of 64.5%. Univariate analysis demonstrated the following factors as poor prognostic indicators for relapse-free survival (RFS) against a median follow-up of 40.25 months: gastrointestinal (GI) bleeding (P = 0.009), non-gastric tumor location (P = 0.001), large tumor size (P = 0.022), high mitotic index (P < 0.001), high cellularity (P = 0.012), tumor rupture (P = 0.013), absent or low expression of PTEN (P = 0.036), and Ki-67 LI >1% (P = 0.043). Gastrointestinal bleeding (hazard ratio, 3.85; 95% confidence interval, 1.63 to 9.10; P = 0.002) was a negative independent risk predictor in multivariate analysis, in addition to tumor size (P = 0.023), and mitotic index (P = 0.002). In addition, GI bleeding showed a good ability to predict recurrence potential, when included in our re-modified risk stratification criteria. Conclusions This study suggests that GI bleeding is an independent predictor of poor prognosis for RFS in primary GISTs. Expression of PTEN and Ki-67 are correlated with high risk potential and may predict early recurrence in univariate analysis

MiR-20a Induces Cell Radioresistance by Activating the PTEN/PI3K/Akt Signaling Pathway in Hepatocellular Carcinoma

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Yuqin; Zheng, Lin; Department of Pathology, Nanfang Hospital, Southern Medical University, Guangzhou, Guangdong Province

2015-08-01

Purpose: To investigate the role of miR-20a in hepatocellular carcinoma (HCC) cell radioresistance, which may reveal potential strategies to improve treatment. Methods and Materials: The expression of miR-20a and PTEN were detected in HCC cell lines and paired primary tissues by quantitative real-time polymerase chain reaction. Cell radiation combined with colony formation assays was administrated to discover the effect of miR-20a on radiosensitivity. Bioinformatics prediction and luciferase assay were used to identify the target of miR-20a. The phosphatidylinositol 3-kinase inhibitor LY294002 was used to inhibit phosphorylation of Akt, to verify whether miR-20a affects HCC cell radioresistance through activating the PTEN/PI3K/Aktmore » pathway. Results: MiR-20a levels were increased in HCC cell lines and tissues, whereas PTEN was inversely correlated with it. Overexpression of miR-20a in Bel-7402 and SMMC-7721 cells enhances their resistance to the effect of ionizing radiation, and the inhibition of miR-20a in HCCLM3 and QGY-7701 cells sensitizes them to it. PTEN was identified as a direct functional target of miR-20a for the induction of radioresistance. Overexpression of miR-20a activated the PTEN/PI3K/Akt signaling pathway. Additionally, the kinase inhibitor LY294002 could reverse the effect of miR-20a–induced radioresistance. Conclusion: MiR-20a induces HCC cell radioresistance by activating the PTEN/PI3K/Akt pathway, which suggests that miR-20a/PTEN/PI3K/Akt might represent a target of investigation for developing effective therapeutic strategies against HCC.« less

Loss of Cdh1 and Pten Accelerates Cellular Invasiveness and Angiogenesis in the Mouse Uterus1

PubMed Central

Lindberg, Mallory E.; Stodden, Genna R.; King, Mandy L.; MacLean, James A.; Mann, Jordan L.; DeMayo, Francesco J.; Lydon, John P.; Hayashi, Kanako

2013-01-01

ABSTRACT E-cadherin (CDH1) is a cell adhesion molecule that coordinates key morphogenetic processes regulating cell growth, cell proliferation, and apoptosis. Loss of CDH1 is a trademark of the cellular event epithelial to mesenchymal transition, which increases the metastatic potential of malignant cells. PTEN is a tumor-suppressor gene commonly mutated in many human cancers, including endometrial cancer. In the mouse uterus, ablation of Pten induces epithelial hyperplasia, leading to endometrial carcinomas. However, loss of Pten alone does not affect longevity until around 5 mo. Similarly, conditional ablation of Cdh1 alone does not predispose mice to cancer. In this study, we characterized the impact of dual Cdh1 and Pten ablation (Cdh1d/d Ptend/d) in the mouse uterus. We observed that Cdh1d/d Ptend/d mice died at Postnatal Days 15–19 with massive blood loss. Their uteri were abnormally structured with curly horns, disorganized epithelial structure, and increased cell proliferation. Co-immunostaining of KRT8 and ACTA2 showed invasion of epithelial cells into the myometrium. Further, the uteri of Cdh1d/d Ptend/d mice had prevalent vascularization in both the endometrium and myometrium. We also observed reduced expression of estrogen and progesterone receptors, loss of cell adherens, and tight junction molecules (CTNNB1 and claudin), as well as activation of AKT in the uteri of Cdh1d/d Ptend/d mice. However, complex hyperplasia was not found in the uteri of Cdh1d/d Ptend/d mice. Collectively, these findings suggest that ablation of Pten with Cdh1 in the uterus accelerates cellular invasiveness and angiogenesis and causes early death. PMID:23740945

Quantitative MRI Establishes the Efficacy of PI3K Inhibitor (GDC-0941) Multi-Treatments in PTEN-deficient Mice Lymphoma

PubMed Central

WULLSCHLEGER, STEPHAN; GARCÍA-MARTÍNEZ, JUAN M.; DUCE, SUZANNE L.

2012-01-01

Aim To assess the efficacy of multiple treatment of phosphatidylinositol-3-kinase (PI3K) inhibitor on autochthonous tumours in phosphatase and tensin homologue (Pten)-deficient genetically engineered mouse cancer models using a longitudinal magnetic resonance imaging (MRI) protocol. Materials and Methods Using 3D MRI, B-cell follicular lymphoma growth was quantified in a Pten+/−Lkb1+/hypo mouse line, before, during and after repeated treatments with a PI3K inhibitor GDC-0941 (75 mg/kg). Results Mean pre-treatment linear tumour growth rate was 16.5±12.8 mm3/week. Repeated 28-day GDC-0941 administration, with 21 days “off-treatment”, induced average tumour regression of 41±7%. Upon cessation of the second treatment (which was not permanently cytocidal), tumours re-grew with an average linear growth rate of 40.1±15.5 mm3/week. There was no evidence of chemoresistance. Conclusion This protocol can accommodate complex dosing schedules, as well as combine different cancer therapies. It reduces biological variability problems and resulted in a 10-fold reduction in mouse numbers compared with terminal assessment methods. It is ideal for preclinical efficacy studies and for phenotyping molecularly characterized mouse models when investigating gene function. PMID:22287727

Targeting of microRNA-21-5p protects against seizure damage in a kainic acid-induced status epilepticus model via PTEN-mTOR.

PubMed

Tang, Chongyang; Gu, Yunhe; Wang, Haiyang; Wu, Hongmei; Wang, Yu; Meng, Yao; Han, Zhibin; Gu, Yifei; Ma, Wei; Jiang, Zhenfeng; Song, Yuanyuan; Na, Meng; Lu, Dunyue; Lin, Zhiguo

2018-05-04

Studies have shown that microRNAs play a role in the development of epilepsy by regulating downstream target messenger (m)RNA. The present study aims to determine the changes associated with microRNA-21-5p (miR-21-5p) during epileptogenesis in a kainic acid rat model, and to assess whether the PTEN-mTOR pathway is a target of miR-21-5p. Reverse transcription polymerase chain reaction (RT-PCR) was used to examine the quantitative expressions of miR-21-5p and PTEN, and Western blotting was used to test the activity of mTOR in the acute, latent, and chronic stages of epileptogenesis. The antagomir of miR-21-5p was injected into the intracerebroventricular space using a microsyringe. Neuronal death and epilepsy discharge were assessed by Nissl staining and electroencephalography (EEG), respectively. The Morris water maze (MWM) was used to assess the cognitive impairment in rats after status epilepticus (SE). Both miR-21-5p and mTOR were upregulated and PTEN was downregulated in rats during acute, latent, and chronic stages of epileptogenesis when compared with those of the control. After using antagomir miR-21-5p in vivo, miR-21-5p and mTOR decreased and the expression of PTEN increased compared with that in the SE model. The silencing of miR-21-5p diminished the number of abnormal spikes on EEG and decreased the number of neuron deletions on Nissl staining. The cognitive and memory impairment caused by epilepsy could also be improved after miR-21-5p knockdown in vivo. The results of the present study demonstrate that PTEN-mTOR is the target of miR-21-5p in a kainic acid model of epilepsy. The knockout of miR-21-5p decreases the neuronal damage in stages of epileptogenesis. The miR-21-5p/PTEN/mTOR axis may be a potential target for preventing and treating seizures and epileptic damage. Copyright © 2018 Elsevier B.V. All rights reserved.

A Transition Zone Showing Highly Discontinuous or Alternating Levels of Stem Cell and Proliferation Markers Characterizes the Development of PTEN-Haploinsufficient Colorectal Cancer.

PubMed

Arvai, Kevin J; Hsu, Ya-Hsuan; Lee, Lobin A; Jones, Dan

2015-01-01

Stepwise acquisition of oncogene mutations and deletion/inactivation of tumor suppressor genes characterize the development of colorectal cancer (CRC). These genetic events interact with discrete morphologic transitions from hyperplastic mucosa to adenomatous areas, followed by in situ malignant transformation and finally invasive carcinoma. The goal of this study was to identify tissue markers of the adenoma-carcinoma morphogenetic transitions in CRC. We analyzed the patterns of expression of growth regulatory and stem cell markers across these distinct morphologic transition zones in 735 primary CRC tumors. In 202 cases with preserved adenoma-adenocarcinoma transition, we identified, in 37.1% of cases, a zone of adenomatous epithelium, located immediately adjacent to the invasive component, that showed rapidly alternating intraglandular stretches of PTEN+ and PTEN- epithelium. This zone exactly overlapped with similar alternating expression of Ki-67 and inversely with the transforming growth factor-beta (TGF-β) growth regulator SMAD4. These zones also show parallel alternating levels and/or subcellular localization of multiple cancer stem/progenitor cell (CSC) markers, including β-catenin/CTNNB1, ALDH1, and CD44. PTEN was always re-expressed in the invasive tumor in these cases, unlike those with complete loss of PTEN expression. Genomic microarray analysis of CRC with prominent CSC-like expansions demonstrated a high frequency of PTEN genomic deletion/haploinsufficiency in tumors with CSC-like transition zones (62.5%) but not in tumors with downregulated but non-alternating PTEN expression (14.3%). There were no significant differences in the levels of KRAS mutation or CTNNB1 mutation in CSC-like tumors as compared to unselected CRC cases. In conclusion, we have identified a distinctive CSC-like pre-invasive transition zone in PTEN-haploinsufficient CRC that shows convergent on-off regulation of the PTEN/AKT, TGF-β/SMAD and Wnt/β-catenin pathways. This

The GAS5/miR-222 Axis Regulates Proliferation of Gastric Cancer Cells Through the PTEN/Akt/mTOR Pathway.

PubMed

Li, Yanhua; Gu, Junjiao; Lu, Hong

2017-12-01

Several lines of evidence have indicated that growth arrest-specific transcript 5 (GAS5) functions as a tumor suppressor and is aberrantly expressed in multiple cancers. GAS5 was found to be downregulated in gastric cancer (GC) tissues, and ectopic expression of GAS5 inhibited GC cell proliferation. The present study aimed to explore the underlying mechanisms of GAS5 involved in GC cell proliferation. GAS5 and miR-222 expressions in GC cell lines were estimated by quantitative real-time polymerase chain reaction. The effects of GAS5 and miR-222 on GC cell proliferation were assessed by MTT assay and 5-bromo-2-deoxyuridine (BrdU) incorporation assays. The interaction between GAS5 and miR-222 was confirmed by luciferase reporter assay and RNA immunoprecipitation assay. The protein levels of the phosphatase and tensin homolog (PTEN), phosphorylated protein kinase B (Akt) (p-Akt), Akt, phosphorylated mammalian target of rapamycin (mTOR) (p-mTOR), and mTOR were determined by western blot. GAS5 was downregulated and miR-222 was upregulated in GC cells. GAS5 directly targeted and suppressed miR-222 expression. GAS5 overexpression and miR-222 inhibition suppressed cell proliferation, increased PTEN protein level and decreased p-Akt and p-mTOR protein levels in GC cells while GAS5 knockdown and miR-222 overexpression exhibited the opposite effects. Moreover, mechanistic analyses revealed that GAS5 regulated GC cell proliferation through the PTEN/Akt/mTOR pathway by negatively regulating miR-222. GAS5/miR-222 axis regulated proliferation of GC cells through the PTEN/Akt/mTOR pathway, which facilitated the development of lncRNA-directed therapy against this deadly disease.

A phosphatase-independent gain-of-function mutation in PTEN triggers aberrant cell growth in astrocytes through an autocrine IGF-1 loop.

PubMed

Fernández, S; Genis, L; Torres-Alemán, I

2014-08-07

Loss-of-function mutations in the phosphatase PTEN (phosphatase and tensin homolog deleted on chromosome10) contribute to aberrant cell growth in part through upregulation of the mitogenic IGF-1/PI3K/Akt pathway. In turn, this pathway exerts a homeostatic feedback over PTEN. Using mutagenesis analysis to explore a possible impact of this mutual control on astrocyte growth, we found that truncation of the C-terminal region of PTEN (Δ51) associates with a marked increase in NFκB activity, a transcription factor overactivated in astrocyte tumors. Whereas mutations of PTEN are considered to lead to a loss-of-function, PTENΔ51, a truncation that comprises a region frequently mutated in human gliomas, displayed a neomorphic (gain-of-function) activity that was independent of its phosphatase activity. This gain-of-function of PTENΔ51 includes stimulation of IGF-1 synthesis through protein kinase A activation of the IGF-1 promoter. Increased IGF-1 originates an autocrine loop that activates Akt and NFκB. Constitutive activation of NFκB in PTENΔ51-expressing astrocytes leads to aberrant cell growth; astrocytes expressing this mutant PTEN generate colonies in vitro and tumors in vivo. Mutations converting a tumor suppressor such as PTEN into a tumor promoter through a gain-of-function involving IGF-1 production may further our understanding of the role played by this growth factor in glioma growth and help us define druggable targets for personalized therapy.

Combined image and genomic analysis of high-grade serous ovarian cancer reveals PTEN loss as a common driver event and prognostic classifier.

PubMed

Martins, Filipe C; Santiago, Ines de; Trinh, Anne; Xian, Jian; Guo, Anne; Sayal, Karen; Jimenez-Linan, Mercedes; Deen, Suha; Driver, Kristy; Mack, Marie; Aslop, Jennifer; Pharoah, Paul D; Markowetz, Florian; Brenton, James D

2014-12-17

TP53 and BRCA1/2 mutations are the main drivers in high-grade serous ovarian carcinoma (HGSOC). We hypothesise that combining tissue phenotypes from image analysis of tumour sections with genomic profiles could reveal other significant driver events. Automatic estimates of stromal content combined with genomic analysis of TCGA HGSOC tumours show that stroma strongly biases estimates of PTEN expression. Tumour-specific PTEN expression was tested in two independent cohorts using tissue microarrays containing 521 cases of HGSOC. PTEN loss or downregulation occurred in 77% of the first cohort by immunofluorescence and 52% of the validation group by immunohistochemistry, and is associated with worse survival in a multivariate Cox-regression model adjusted for study site, age, stage and grade. Reanalysis of TCGA data shows that hemizygous loss of PTEN is common (36%) and expression of PTEN and expression of androgen receptor are positively associated. Low androgen receptor expression was associated with reduced survival in data from TCGA and immunohistochemical analysis of the first cohort. PTEN loss is a common event in HGSOC and defines a subgroup with significantly worse prognosis, suggesting the rational use of drugs to target PI3K and androgen receptor pathways for HGSOC. This work shows that integrative approaches combining tissue phenotypes from images with genomic analysis can resolve confounding effects of tissue heterogeneity and should be used to identify new drivers in other cancers.

Conditional genetic deletion of PTEN after a spinal cord injury enhances regenerative growth of CST axons and motor function recovery in mice.

PubMed

Danilov, Camelia A; Steward, Oswald

2015-04-01

Previous studies indicate that conditional genetic deletion of phosphatase and tensin homolog (PTEN) in neonatal mice enhances the ability of axons to regenerate following spinal cord injury (SCI) in adults. Here, we assessed whether deleting PTEN in adult neurons post-SCI is also effective, and whether enhanced regenerative growth is accompanied by enhanced recovery of voluntary motor function. PTEN(loxP/loxP) mice received moderate contusion injuries at cervical level 5 (C5). One group received unilateral injections of adeno-associated virus expressing CRE (AAV-CRE) into the sensorimotor cortex; controls received a vector expressing green fluorescent protein (AAV-GFP) or injuries only (no vector injections). Forelimb function was tested for 14weeks post-SCI using a grip strength meter (GSM) and a hanging task. The corticospinal tract (CST) was traced by injecting mini-ruby BDA into the sensorimotor cortex. Forelimb gripping ability was severely impaired immediately post-SCI but recovered slowly over time. The extent of recovery was significantly greater in PTEN-deleted mice in comparison to either the AAV-GFP group or the injury only group. BDA tract tracing revealed significantly higher numbers of BDA-labeled axons in caudal segments in the PTEN-deleted group compared to control groups. In addition, in the PTEN-deleted group, there were exuberant collaterals extending from the main tract rostral to the lesion and into and around the scar tissue at the injury site. These results indicate that PTEN deletion in adult mice shortly post-SCI can enhance regenerative growth of CST axons and forelimb motor function recovery. Copyright © 2015 Elsevier Inc. All rights reserved.

Association of the hypermethylation status of PTEN tumor suppressor gene with the risk of breast cancer among Kurdish population from Western Iran.

PubMed

Yari, Kheirollah; Payandeh, Mehrdad; Rahimi, Zohreh

2016-06-01

Breast cancer is the most common cancer with high morbidity and mortality among women worldwide. Aberrant hypermethylation in promoter regions of the tumor suppressor genes such as PTEN gene is a key event in the progression and development of breast cancer. The aim of the present study was to evaluate an association between PTEN gene methylation status with the risk of breast cancer in an Iranian population. We studied 255 individuals, including 103 patients with breast cancer, 102 first-degree female relatives of patients (mother, sister, or daughter of patients), and 50 healthy individuals as a control group. Genomic DNA was extracted from peripheral blood leukocytes, and the PTEN promoter methylation status was detected using methylation-specific PCR (MSP) method with specific methylated and unmethylated primers. In some samples, direct DNA sequencing was used to confirm the results obtained by the MSP method. The frequency of PTEN-methylated (MM) genotype was 6 % in the healthy control group, 23.3 % in relatives of patients, and 41.7 % in patients (χ (2) = 24.62, p < 0.001). There were significant differences in the frequency of PTEN-methylated genotype between healthy control compared to that in patients (χ (2) = 15.1, p < 0.001) and also compared to that in relatives of patients (χ (2) = 6.9, p = 0.009). In the presence of PTEN MM genotype, there was a 3.1-fold susceptibility to breast cancer compared to the UU genotype (p < 0.001). Also, in the presence of PTEN M allele, the risk of breast cancer was 2.71-fold compared to the presence of U allele (p < 0.001). Our findings indicated increased frequency of hypermethylation of PTEN promoter in the studied patients and their relatives that could be considered as one of the epigenetic factors affecting the risk of breast cancer in Iranians.

Interactions of the Auxilin-1 PTEN-like Domain with Model Membranes Result in Nanoclustering of Phosphatidyl Inositol Phosphates

PubMed Central

Kalli, Antreas C.; Morgan, Gareth; Sansom, Mark S.P.

2013-01-01

Auxilin-1 is a neuron-specific membrane-binding protein involved in a late stage of clathrin-mediated endocytosis. It recruits Hsc70, thus initiating uncoating of the clathrin-coated vesicles. Interactions of auxilin-1 with the vesicle membrane are crucial for this function and are mediated via an N-terminal PTEN-like domain. We have used multiscale molecular dynamics simulations to probe the interactions of the auxilin-1 PTEN-like domain with lipid bilayers containing differing phospholipid composition, including bilayers containing phosphatidyl inositol phosphates. Our results suggest a novel, to our knowledge, model for the auxilin/membrane encounter and subsequent interactions. Negatively charged lipids (especially PIP2) enhance binding of auxilin to lipid bilayers and facilitate its correct orientation relative to the membrane. Mutations in three basic residues (R301E/R307E/K311E) of the C2 subdomain of the PTEN-like domain perturbed its interaction with the bilayer, changing its orientation. The interaction of membrane-bound auxilin-1 PTEN-like domain with negatively charged lipid headgroups results in nanoclustering of PIP2 molecules in the adjacent bilayer leaflet. PMID:23823232

Costimulation dependent expression of miR-214 increases the ability of T cells to proliferate by targeting Pten

PubMed Central

Jindra, Peter T.; Bagley, Jessamyn; Godwin, Jonathan G.; Iacomini, John

2010-01-01

T cell activation requires signaling through the T cell receptor (TCR) and costimulatory molecules such as CD28. MicroRNAs (miRNAs) are small noncoding RNAs that regulate gene expression post transcriptionally and are also known to be involved in lymphocyte development and function. Here we set out to examine potential roles of miRNAs in T cell activation by using genome-wide expression profiling to identify miRNAs differentially regulated following T cell activation. One of the miRNAs up-regulated after T cell activation, miR-214, was predicted to be capable of targeting Pten based on bioinformatics and reports suggesting that it targets Pten in ovarian tumor cells. Up-regulation of miR-214 in T cells inversely correlated with PTEN levels. In vivo, transcripts containing the 3' untranslated region (3' UTR) of Pten including the miR-214 target sequence were negatively regulated after T cell activation, and forced expression of miR-214 in T cells led to increased proliferation after stimulation. Blocking CD28 signaling in vivo prevented miR-214 up-regulation in alloreactive T cells. Stimulation of T cells through the TCR alone was not sufficient to result in upregulation of miR-214. Thus, costimulation dependent up-regulation of miR-214 promotes T cell activation by targeting the negative regulator Pten. Thus, the requirement for T cell costimulation is in part related to its ability to regulate expression of miRNAs that control T cell activation. PMID:20548023

Compound heterozygosity for Pten and SHIP augments T-dependent humoral immune responses and cytokine production by CD4+ T cells

PubMed Central

Moody, J L; Jirik, F R

2004-01-01

Tight regulation of the phosphatidylinositiol 3-kinase (PI3K) pathway is essential not only for normal immune system development and responsiveness, but also in the prevention of immunopathology. Indeed, unchecked activation of the PI3K pathway in T cells induces lymphoproliferation and systemic autoimmunity. Evaluating the importance of threshold levels of two key PI3K pathway phosphoinositol phosphatases, we previously reported that mice heterozygous for both Pten and SHIP develop a more rapid progression of a lymphoproliferative autoimmune syndrome than do Pten+\\− mice. Investigating the basis for this difference, we now describe a quantitative and qualitative difference in the antibody responses of C57BL\\6 Pten+\\− SHIP+\\− mice upon challenge with a T-dependent antigen. Suspecting that this phenotypic difference might be the result, at least in part, of a T-helper cell defect, an in vitro analysis of anti-CD3/interleukin (IL)-2-expanded CD4+ T cells was performed. After stimulation with anti-CD3, cells from mice heterozygous for both Pten and SHIP exhibited a striking increase in IL-4 secretion (> 10-fold), without a corresponding increase in T helper 2 (Th2) cell numbers being evident by intracellular staining for this cytokine. Modest increases were also seen for both IL-13 and IFN-γ. Perhaps in keeping with this abnormal in vitro cytokine profile, IgG1 serum levels were significantly elevated in young C57BL\\6 Pten+\\− SHIP+\\− mice. Thus, the relative levels of Pten and SHIP appear to be key variables in CD4+ T-cell function, primarily via their ability to regulate IL-4 production. PMID:15196208

Amphiregulin and PTEN evoke a multimodal mechanism of acquired resistance to PI3K inhibition

PubMed Central

Edgar, Kyle A.; Crocker, Lisa; Cheng, Eric; Wagle, Marie-Claire; Wongchenko, Matthew; Yan, Yibing; Wilson, Timothy R.; Dompe, Nicholas; Neve, Richard M.; Belvin, Marcia; Sampath, Deepak; Friedman, Lori S.; Wallin, Jeffrey J.

2014-01-01

Phosphoinositide-3 kinase (PI3K) signaling pathway alterations occur broadly in cancer and PI3K is a promising therapeutic target. Here, we investigated acquired resistance to GDC-0941, a PI3K inhibitor in clinical trials. Colorectal cancer (CRC) cells made to be resistant to GDC-0941 were discovered to secrete amphiregulin, which resulted in increased EGFR/MAPK signaling. Moreover, prolonged PI3K pathway inhibition in cultured cells over a period of months led to a secondary loss of PTEN in 40% of the CRC lines with acquired resistance to PI3K inhibition. In the absence of PI3K inhibitor, these PTEN-null PI3K inhibitor-resistant clones had elevated PI3K pathway signaling and decreased sensitivity to MAPK pathway inhibitors. Importantly, PTEN loss was not able to induce resistance to PI3K inhibitors in the absence of amphiregulin, indicating a multimodal mechanism of acquired resistance. The combination of PI3K and MAPK pathway inhibitors overcame acquired resistance in vitro and in vivo. PMID:25053989

Amphiregulin and PTEN evoke a multimodal mechanism of acquired resistance to PI3K inhibition.

PubMed

Edgar, Kyle A; Crocker, Lisa; Cheng, Eric; Wagle, Marie-Claire; Wongchenko, Matthew; Yan, Yibing; Wilson, Timothy R; Dompe, Nicholas; Neve, Richard M; Belvin, Marcia; Sampath, Deepak; Friedman, Lori S; Wallin, Jeffrey J

2014-03-01

Phosphoinositide-3 kinase (PI3K) signaling pathway alterations occur broadly in cancer and PI3K is a promising therapeutic target. Here, we investigated acquired resistance to GDC-0941, a PI3K inhibitor in clinical trials. Colorectal cancer (CRC) cells made to be resistant to GDC-0941 were discovered to secrete amphiregulin, which resulted in increased EGFR/MAPK signaling. Moreover, prolonged PI3K pathway inhibition in cultured cells over a period of months led to a secondary loss of PTEN in 40% of the CRC lines with acquired resistance to PI3K inhibition. In the absence of PI3K inhibitor, these PTEN-null PI3K inhibitor-resistant clones had elevated PI3K pathway signaling and decreased sensitivity to MAPK pathway inhibitors. Importantly, PTEN loss was not able to induce resistance to PI3K inhibitors in the absence of amphiregulin, indicating a multimodal mechanism of acquired resistance. The combination of PI3K and MAPK pathway inhibitors overcame acquired resistance in vitro and in vivo.

PTEN differentially regulates expressions of ICAM-1 and VCAM-1 through PI3K/Akt/GSK-3β/GATA-6 signaling pathways in TNF-α-activated human endothelial cells.

PubMed

Tsoyi, Konstantin; Jang, Hwa Jin; Nizamutdinova, Irina Tsoy; Park, Kyungok; Kim, Young Min; Kim, Hye Jung; Seo, Han Geuk; Lee, Jae Heun; Chang, Ki Churl

2010-11-01

Phosphotase and tensin homolog deleted on chromosome 10 (PTEN) is a potent negative regulator of PI3K/Akt pathway. Here, we tried to elucidate the role of PTEN in the regulation of endothelial adhesion molecules, vascular cell adhesion molecule (VCAM)-1 and intracellular adhesion molecule (ICAM)-1, induced by TNF-α in human endothelial cells (ECs). Transfection with PTEN overexpressing vector resulted in the significant decrease in phosphorylation of Akt in TNF-α-treated ECs. PTEN strongly inhibited VCAM-1 but not ICAM-1, however this inhibitory effect was reversed by co-transfection with constitutively active-Akt (CA-Akt-HA) in TNF-α-stimulated ECs. Additionally, silencing of PTEN with specific siRNA showed significant increase of phosphor-Akt compared with TNF-α alone treated ECs. siPTEN significantly upregulated VCAM-1 but was indifferent to ICAM-1 in TNF-α-treated cells. Further, chromatin immunoprecipitation (ChIP) assay showed that PTEN targets GATA-6 but not IRF-1 binding to VCAM-1 promoter. In addition, GATA-6 is associated with glycogen synthesis kinase-3beta (GSK-3β) which is in turn regulated by PTEN-dependent Akt activity. Finally, PTEN significantly prevented monocyte adhesion to TNF-α-induced ECs probably through VCAM-1 regulation. It is concluded that PTEN selectively inhibits expression of VCAM-1 but not ICAM-1 through modulation of PI3K/Akt/GSK-3β/GATA-6 signaling cascade in TNF-α-treated ECs. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

Voltage-sensing phosphatase: its molecular relationship with PTEN.

PubMed

Okamura, Yasushi; Dixon, Jack E

2011-02-01

Voltage-sensing phosphoinositide phosphatase (VSP) contains voltage sensor and cytoplasmic phosphatase domains. A unique feature of this protein is that depolarization-induced motions of the voltage sensor activate PtdIns(3,4,5)P(3) and PtdIns(4,5)P(2) phosphatase activities. VSP exhibits remarkable structural similarities with PTEN, the phosphatase and tensin homolog deleted on chromosome 10. These similarities include the cytoplasmic phosphatase region, the phosphoinositide binding region, and the putative membrane interacting C2 domain.

PPARbeta/delta agonist stimulates human lung carcinoma cell growth through inhibition of PTEN expression: the involvement of PI3K and NF-kappaB signals.

PubMed

Han, ShouWei; Ritzenthaler, Jeffrey D; Zheng, Ying; Roman, Jesse

2008-06-01

Recent studies suggest that activation of peroxisome proliferator-activated receptor beta/delta (PPARbeta/delta) promotes cancer cell survival. We previously demonstrated that a selective PPARbeta/delta agonist, GW501516, stimulated human non-small cell lung carcinoma (NSCLC) cell growth. Here, we explore the mechanisms responsible for this effect. We show that GW501516 decreased phosphate and tensin homolog deleted on chromosome 10 (PTEN), a tumor suppressor known to decrease cell growth and induce apoptosis. Activation of PPARbeta/delta and phosphatidylinositol 3-kinase (PI3K)/Akt signaling was associated with inhibition of PTEN. GW501516 increased NF-kappaB DNA binding activity and p65 protein expression through activation of PPARbeta/delta and PI3K/Akt signals and enhanced the physical interactions between PPARbeta/delta and p65 protein. Conversely, inhibition of PI3K and silencing of p65 by small RNA interference (siRNA) blocked the effect of GW501516 on PTEN expression and on NSCLC cell proliferation. GW501516 also inhibited IKBalpha protein expression. Silencing of IKBalpha enhanced the effect of GW501516 on PTEN protein expression and on cell proliferation. It also augmented the GW501516-induced complex formation of PPARbeta/delta and p65 proteins. Overexpression of PTEN suppressed NSCLC cell growth and eliminated the effect of GW501516 on phosphorylation of Akt. Together, our observations suggest that GW501516 induces the proliferation of NSCLC cells by inhibiting the expression of PTEN through activation of PPARbeta/delta, which stimulates PI3K/Akt and NF-kappaB signaling. Overexpression of PTEN overcomes this effect and unveils PPARbeta/delta and PTEN as potential therapeutic targets in NSCLC.

Analysis of PTEN expression in large intestine polyps and its relation to the recognized histopathological and clinical risk factors for cancer development in this location

PubMed Central

Śnietura, Mirosław; Pigłowski, Wojciech; Rdes, Jerzy; Kopeć, Agnieszka; Młynarczyk-Liszka, Joanna; Rudzki, Marek; Hudyka, Krystyna; Arendt, Jerzy; Lange, Dariusz

2012-01-01

Aim of the study PTEN is an important gene whose protein product is double specific phosphatase holding key regulatory functions in sending signals from membrane receptors for growth factors into the cell downstreams. Its participation, mainly by PI3K/AKT signaling pathway in the pathomechanism of many malignant cancers was unambiguously confirmed. The PTEN function gets disturbed on many levels and for various reasons. Disorders of PTEN protein expression seem to be even more common in many carcinomas. The aim of the study is to enquire the meaning of PTEN expression in the cancer transformation process in large intestine glandular polyps. Material and methods The group includes 40 patients, 21 men and 19 women, age median 64 years (51–83) qualified to endoscopic removal of large intestine polyp. Tissue material obtained during polyp removal endoscopy was immediately fixed in 4% buffered formalin solution with the mixture of phosphatase activity inhibitors (PhosStop Roche). Time of fixation 24–48 h. After fixation, the material was embedded in paraffin. PTEN visualization was based on specific rabbit monoclonal antibodies (Cell Signaling). The expression of PTEN protein in large intestine and rectum polyps was marked by a semi-quantitative method and an attempt to correlate the results with the acknowledged clinical and histopathological malignancy risk factors was undertaken. Results Loss or weakening of protein expression was found in 45% cases. Moreover, the relationship between polyp diameter and a loss of PTEN expression was proved. The received results can indicate a significant participation of PTEN gene in early oncogenesis stages of large intestine cancer. PMID:23788900

The role of insulin-like-growth factor binding protein 2 (IGFBP2) and phosphatase and tensin homologue (PTEN) in the regulation of myoblast differentiation and hypertrophy.

PubMed

Sharples, Adam P; Al-Shanti, Nasser; Hughes, David C; Lewis, Mark P; Stewart, Claire E

2013-06-01

The complex actions of the insulin-like-growth factor binding proteins (IGFBPs) in skeletal muscle are becoming apparent, with IGFBP2 being implicated in skeletal muscle cell proliferation and differentiation (Ernst et al., 1992; Sharples et al., 2010). Furthermore, PTEN signalling has been linked to IGFBP2 action in other cell types by co-ordinating downstream Akt signalling, a known modulator of myoblast differentiation. The present study therefore aimed to determine the interaction between IGFBP2 and PTEN on myoblast differentiation. It has previously been established that C2C12 cells have high IGFBP2 gene expression upon transfer to low serum media, and that expression reduces rapidly as cells differentiate over 72 h [1]. Wishing to establish a potential role for IGFBP2 in this model, a neutralising IGFBP2 antibody was administered to C2C12 myoblasts upon initiation of differentiation. Myoblasts subsequently displayed reduced morphological differentiation (myotube number), biochemical differentiation (creatine kinase) and myotube hypertrophy (myotube area) with an early reduction in Akt phosphorylation. Knock-down of phosphatase and tensin homologue (PTEN) using siRNA in the absence of the neutralising antibody did not improve differentiation or hypertrophy vs. control conditions, however, in the presence of the neutralising IGFBP2 antibody, differentiation was restored and importantly hypertrophy exceeded that of control levels. Overall, these data suggest that; 1) reduced early availability of IGFBP2 can inhibit myoblast differentiation at later time points, 2) knock-down of PTEN levels can restore myoblast differentiation in the presence of neutralising IGFBP2 antibody, and 3) PTEN inhibition acts as a potent inducer of myotube hypertrophy when the availability of IGFBP2 is reduced in C2C12 myoblasts. Copyright © 2013 Elsevier Ltd. All rights reserved.

Opposite effects of dihydrosphingosine 1-phosphate and sphingosine 1-phosphate on transforming growth factor-beta/Smad signaling are mediated through the PTEN/PPM1A-dependent pathway.

PubMed

Bu, Shizhong; Kapanadze, Bagrat; Hsu, Tien; Trojanowska, Maria

2008-07-11

Transforming growth factor-beta (TGF-beta) is an important regulator of physiological connective tissue biosynthesis and plays a central role in pathological tissue fibrosis. Previous studies have established that a biologically active lipid mediator, sphingosine 1-phosphate (S1P), mimics some of the profibrotic functions of TGF-beta through cross-activation of Smad signaling. Here we report that another product of sphingosine kinase, dihydrosphingosine 1-phosphate (dhS1P), has an opposite role in the regulation of TGF-beta signaling. In contrast to S1P, dhS1P inhibits TGF-beta-induced Smad2/3 phosphorylation and up-regulation of collagen synthesis. The effects of dhS1P require a lipid phosphatase, PTEN, a key modulator of cell growth and survival. dhS1P stimulates phosphorylation of the C-terminal domain of PTEN and its subsequent translocation into the nucleus. We demonstrate a novel function of nuclear PTEN as a co-factor of the Smad2/3 phosphatase, PPM1A. Complex formation of PTEN with PPM1A does not require the lipid phosphatase activity but depends on phosphorylation of the serine/threonine residues located in the C-terminal domain of PTEN. Upon complex formation with PTEN, PPM1A is protected from degradation induced by the TGF-beta signaling. Consequently, overexpression of PTEN abrogates TGF-beta-induced Smad2/3 phosphorylation. This study establishes a novel role for nuclear PTEN in the stabilization of PPM1A. PTEN-mediated cross-talk between the sphingolipid and TGF-beta signaling pathways may play an important role in physiological and pathological TGF-beta signaling.

Methylseleninic acid super-activates p53-senescence cancer progression barrier in prostate lesions of Pten-knockout mouse

PubMed Central

Wang, Lei; Guo, Xiaolan; Wang, Ji; Jiang, Cheng; Bosland, Maarten C.; Lü, Junxuan; Deng, Yibin

2015-01-01

Monomethylated selenium (MM-Se) forms that are precursors of methylselenol such as methylseleninic acid (MSeA) differ in metabolism and anti-cancer activities in preclinical cell and animal models from seleno-methionine that had failed to exert preventive efficacy against prostate cancer (PCa) in North American men. Given that human PCa arises from precancerous lesions such as high-grade prostatic intraepithelial neoplasia (HG-PIN) which frequently have lost PTEN tumor suppressor permitting AKT oncogenic signaling, we tested the efficacy of MSeA to inhibit HG-PIN progression in Pten prostate specific knockout (KO) mice and assessed the mechanistic involvement of p53-mediated cellular senescence and of the androgen receptor (AR). We observed that short-term (4 weeks) oral MSeA treatment significantly increased expression of P53 and P21Cip1 proteins and senescence-associated-β-galactosidase staining, and reduced Ki-67 cell proliferation index in Pten KO prostate epithelium. Long-term (25 weeks) MSeA administration significantly suppressed HG-PIN phenotype, tumor weight, and prevented emergence of invasive carcinoma in Pten KO mice. Mechanistically, the long-term MSeA treatment not only sustained P53-mediated senescence, but also markedly reduced AKT phosphorylation and AR abundance in the Pten KO prostate. Importantly, these cellular and molecular changes were not observed in the prostate of wild type littermates which were similarly treated with MSeA. Since p53 signaling is likely to be intact in HG-PIN compared to advanced PCa, the selective super-activation of p53-mediated senescence by MSeA suggests a new paradigm of cancer chemoprevention by strengthening a cancer progression barrier through induction of irreversible senescence with additional suppression of AR and AKT oncogenic signaling. PMID:26511486

MiR-155 promotes cell proliferation and inhibits apoptosis by PTEN signaling pathway in the psoriasis.

PubMed

Xu, Longjiang; Leng, Hong; Shi, Xin; Ji, Jiang; Fu, Jinxiang; Leng, Hong

2017-06-01

MicroRNAs (miRNAs) have been demonstrated to contribute to malignant progression in psoriasis development. The purposes of the study was to evaluated the effects of miRNA-155 on cell proliferation, migration and apoptosis in psoriasis development via PTEN singaling pathway and identify its direct target protein. Quantitative real-time RT-PCR (qRT-PCR) was performed to examine the level of miR-155 in psoriasis cells, miR-155 was downregulated in a psoriasis cell line Hacat by transfected with small interfering RNA (siRNA), respectively. Cell survival was detected by the MTT assay and colony formation assay. Cell migration and invasion were measured via wound-healing assayand transwell assay. In addition, cell cycle and apoptosis about psoriasis cells was measured by flow cytometry. In this study, qRT-PCR assay showed that the expressions of miR-155 mRNA in psoriasis tissues were significantly higher than that in normal tissues. The assays about cell growth and proliferation showed that miR-155 knockdown led to a significant decrease in cell proliferation which was determined by MTT assay and colony formation assay compared to those of Lv-NC cells. Flow cytometry analysis showed that depletion of miR-155 could cause cell cycle change and the number of apoptotic cells was significantly increased in Lv-miR155 cells compared with control cells. In addition, the expression of several apoptosis-related factors were dramatically changed, such as PTEN, PIP 3 , AKT, p-AKT, Bax and Bcl-2. Our findings indicate that down-regulation of miR-155 significantly inhibits proliferation, migration, invasion and promotes apoptosis through PTEN singaling pathway in psoriasis cells. miR-155 might function as an oncogene miRNA in the progress of psoriasis. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

SPARC Overexpression Inhibits Cell Proliferation in Neuroblastoma and Is Partly Mediated by Tumor Suppressor Protein PTEN and AKT

PubMed Central

Bhoopathi, Praveen; Gorantla, Bharathi; Sailaja, G. S.; Gondi, Christopher S.; Gujrati, Meena; Klopfenstein, Jeffrey D.; Rao, Jasti S.

2012-01-01

Secreted protein acidic and rich in cysteine (SPARC) is also known as BM-40 or Osteonectin, a multi-functional protein modulating cell–cell and cell–matrix interactions. In cancer, SPARC is not only linked with a highly aggressive phenotype, but it also acts as a tumor suppressor. In the present study, we sought to characterize the function of SPARC and its role in sensitizing neuroblastoma cells to radio-therapy. SPARC overexpression in neuroblastoma cells inhibited cell proliferation in vitro. Additionally, SPARC overexpression significantly suppressed the activity of AKT and this suppression was accompanied by an increase in the tumor suppressor protein PTEN both in vitro and in vivo. Restoration of neuroblastoma cell radio-sensitivity was achieved by overexpression of SPARC in neuroblastoma cells in vitro and in vivo. To confirm the role of the AKT in proliferation inhibited by SPARC overexpression, we transfected neuroblastoma cells with a plasmid vector carrying myr-AKT. Myr-AKT overexpression reversed SPARC-mediated PTEN and increased proliferation of neuroblastoma cells in vitro. PTEN overexpression in parallel with SPARC siRNA resulted in decreased AKT phosphorylation and proliferation in vitro. Taken together, these results establish SPARC as an effector of AKT-PTEN-mediated inhibition of proliferation in neuroblastoma in vitro and in vivo. PMID:22567126

Targeting of the tumor suppressor GRHL3 by a miR-21-dependent proto-oncogenic network results in PTEN loss and tumorigenesis.

PubMed

Darido, Charbel; Georgy, Smitha R; Wilanowski, Tomasz; Dworkin, Sebastian; Auden, Alana; Zhao, Quan; Rank, Gerhard; Srivastava, Seema; Finlay, Moira J; Papenfuss, Anthony T; Pandolfi, Pier Paolo; Pearson, Richard B; Jane, Stephen M

2011-11-15

Despite its prevalence, the molecular basis of squamous cell carcinoma (SCC) remains poorly understood. Here, we identify the developmental transcription factor Grhl3 as a potent tumor suppressor of SCC in mice, and demonstrate that targeting of Grhl3 by a miR-21-dependent proto-oncogenic network underpins SCC in humans. Deletion of Grhl3 in adult epidermis evokes loss of expression of PTEN, a direct GRHL3 target, resulting in aggressive SCC induced by activation of PI3K/AKT/mTOR signaling. Restoration of Pten expression completely abrogates SCC formation. Reduced levels of GRHL3 and PTEN are evident in human skin, and head and neck SCC, associated with increased expression of miR-21, which targets both tumor suppressors. Our data define the GRHL3-PTEN axis as a critical tumor suppressor pathway in SCC. 2011 Elsevier Inc. All rights reserved.

Conditional genetic deletion of PTEN after a spinal cord injury enhances regenerative growth of CST axons and motor function recovery in mice

PubMed Central

Danilov, Camelia A.; Steward, Oswald

2015-01-01

Previous studies indicate that conditional genetic deletion of phosphatase and tensin homolog (PTEN) in neonatal mice enhances the ability of axons to regenerate following spinal cord injury (SCI) in adults. Here, we assessed whether deleting PTEN in adult neurons post-SCI is also effective, and whether enhanced regenerative growth is accompanied by enhanced recovery of voluntary motor function. PTENloxP/loxP mice received moderate contusion injuries at cervical level 5 (C5). One group received unilateral injections of adeno-associated virus expressing CRE (AAV-CRE) into the sensorimotor cortex; controls received a vector expressing green fluorescent protein (AAV-GFP) or injuries only (no vector injections). Forelimb function was tested for 14 weeks post-SCI using a grip strength meter (GSM) and a hanging task. The corticospinal tract (CST) was traced by injecting mini-ruby BDA into the sensorimotor cortex. Forelimb gripping ability was severely impaired immediately post-SCI but recovered slowly over time. The extent of recovery was significantly greater in PTEN-deleted mice in comparison to either the AAV-GFP group or the injury only group. BDA tract tracing revealed significantly higher numbers of BDA-labeled axons in caudal segments in the PTEN-deleted group compared to control groups. In addition, in the PTEN-deleted group, there were exuberant collaterals extending from the main tract rostral to the lesion, into and around the scar tissue at the injury site. These results indicate that PTEN deletion in adult mice shortly post-SCI can enhance regenerative growth of CST axons and forelimb motor function recovery. PMID:25704959

Shikonin Inhibites Migration and Invasion of Thyroid Cancer Cells by Downregulating DNMT1

PubMed Central

Zhang, Yue; Sun, Bin; Huang, Zhi

2018-01-01

Background Shikonin is a component of Chinese herbal medicine. The aim of this study was to investigate the effects of shikonin on cell migration of papillary thyroid cancer cells of the TPC-1 cell line in vitro and expression levels of the phosphate and tensin homolog deleted on chromosome 10 (PTEN) and DNA methyltransferase 1 (DNMT1) genes. Material/Methods The Cell Counting Kit-8 (CCK-8) assay was performed to evaluate the proliferation of TPC-1 papillary thyroid cancer cells, and the normal thyroid cells, HTori-3, in vitro. A transwell motility assay was used to analyze the migration of TPC-1 cells. Western blot was performed to determine the expression levels of PTEN and DNMT1 genes. A methylation-specific polymerase chain reaction (PCR) (MSP) assay was used to evaluate the methylation of PTEN. Results Following treatment with shikonin, the cell survival rate of TPC-1 cells decreased in a dose-dependent manner; the inhibitory effects on HTori-3 cells were less marked. Shikonin inhibited TPC-1 cell migration and invasion in a dose-dependent manner. The methylation of PTEN was suppressed by shikonin, which also reduced the expression of DNMT1 in a dose-dependent manner, and increased the expression of PTEN. Overexpression of DNMT1 promoted the migration of TPC-1 cells and the methylation of PTEN. Levels of protein expression of PTEN in TPC-1 cells treated with shikonin decreased, and were increased by DNMT1 knockdown. Conclusions Shikonin suppressed the expression of DNMT1, reduced PTEN gene methylation, and increased PTEN protein expression, leading to the inhibition of TPC-1 cell migration. PMID:29389913

Opposite Effects of Dihydrosphingosine 1-Phosphate and Sphingosine 1-Phosphate on Transforming Growth Factor-β/Smad Signaling Are Mediated through the PTEN/PPM1A-dependent Pathway*S⃞

PubMed Central

Bu, Shizhong; Kapanadze, Bagrat; Hsu, Tien; Trojanowska, Maria

2008-01-01

Transforming growth factor-β (TGF-β) is an important regulator of physiological connective tissue biosynthesis and plays a central role in pathological tissue fibrosis. Previous studies have established that a biologically active lipid mediator, sphingosine 1-phosphate (S1P), mimics some of the profibrotic functions of TGF-β through cross-activation of Smad signaling. Here we report that another product of sphingosine kinase, dihydrosphingosine 1-phosphate (dhS1P), has an opposite role in the regulation of TGF-β signaling. In contrast to S1P, dhS1P inhibits TGF-β-induced Smad2/3 phosphorylation and up-regulation of collagen synthesis. The effects of dhS1P require a lipid phosphatase, PTEN, a key modulator of cell growth and survival. dhS1P stimulates phosphorylation of the C-terminal domain of PTEN and its subsequent translocation into the nucleus. We demonstrate a novel function of nuclear PTEN as a co-factor of the Smad2/3 phosphatase, PPM1A. Complex formation of PTEN with PPM1A does not require the lipid phosphatase activity but depends on phosphorylation of the serine/threonine residues located in the C-terminal domain of PTEN. Upon complex formation with PTEN, PPM1A is protected from degradation induced by the TGF-β signaling. Consequently, overexpression of PTEN abrogates TGF-β-induced Smad2/3 phosphorylation. This study establishes a novel role for nuclear PTEN in the stabilization of PPM1A. PTEN-mediated cross-talk between the sphingolipid and TGF-β signaling pathways may play an important role in physiological and pathological TGF-β signaling. PMID:18482992

The tumor suppressor PTEN and the PDK1 kinase regulate formation of the columnar neural epithelium

PubMed Central

Grego-Bessa, Joaquim; Bloomekatz, Joshua; Castel, Pau; Omelchenko, Tatiana; Baselga, José; Anderson, Kathryn V

2016-01-01

Epithelial morphogenesis and stability are essential for normal development and organ homeostasis. The mouse neural plate is a cuboidal epithelium that remodels into a columnar pseudostratified epithelium over the course of 24 hr. Here we show that the transition to a columnar epithelium fails in mutant embryos that lack the tumor suppressor PTEN, although proliferation, patterning and apical-basal polarity markers are normal in the mutants. The Pten phenotype is mimicked by constitutive activation of PI3 kinase and is rescued by the removal of PDK1 (PDPK1), but does not depend on the downstream kinases AKT and mTORC1. High resolution imaging shows that PTEN is required for stabilization of planar cell packing in the neural plate and for the formation of stable apical-basal microtubule arrays. The data suggest that appropriate levels of membrane-associated PDPK1 are required for stabilization of apical junctions, which promotes cell elongation, during epithelial morphogenesis. DOI: http://dx.doi.org/10.7554/eLife.12034.001 PMID:26809587

SPINK1 Overexpression in Localized Prostate Cancer: a Rare Event Inversely Associated with ERG Expression and Exclusive of Homozygous PTEN Deletion.

PubMed

Huang, Kuo-Cheng; Evans, Andrew; Donnelly, Bryan; Bismar, Tarek A

2017-04-01

SPINK1 is proposed as potential prognostic marker in prostate cancer (PCA). However, its relation to PTEN and ERG in localized PCA remains unclear. The study population consisted of two independent cohorts of men treated by radical prostatectomy for localized PCA (discovery n = 218 and validation n = 129). Patterns of association between SPINK1 and each of ERG and PTEN were evaluated by immunohistochemistry and fluorescence in situ hybridization. Associations between SPINK1 expression and various pathologic parameters and clinical outcome were also investigated. SPINK1 was expressed in 15.3 % and 10.9 % of cases in the discovery and validation cohort, respectively. SPINK expression was observed in 5.56 % of high-grade prostatic intraepithelial neoplasia and 1.1 % of adjacent morphologically benign prostatic glands. SPINK1 and ERG expression were almost exclusive, with only 1.0 % of the cases co-expressing both in the same core sample. SPINK1 interfocal and within-core heterogeneity was noted in 29.2 % and 64.6 % of cases, respectively. SPINK1 expression was not significantly associated with PTEN deletion in the two cohorts (p = 0.871 for discovery cohort and p = 0.293 for validation cohort). While SPINK1 expression did occur with hemizygous PTEN deletion, there was a complete absence of SPINK1 expression in PCA showing homozygous PTEN deletion, which was confirmed in the validation cohort (p = 0.02). Despite SPINK1's association with higher Gleason score (>7) (p = 0.02), it was not associated with other pathological parameters or biochemical recurrence post-radical prostatectomy. We documented absolute exclusivity between SPINK1 overexpression and homozygous PTEN deletion in localized PCA. SPINK1 and ERG expressions are exclusive events in PCA. SPINK1 is not of added prognostic value in localized PCA.

ZN2+ INDUCES COX-2 EXPRESSION THROUGH DOWNREGULATION OF LIPID PHOSPHATASE PTEN

EPA Science Inventory

Zn2+ Induces COX-2 Expression through Downregulation of Lipid Phosphatase PTEN
Weidong Wu*, James M. Samet, Philip A. Bromberg*?, Young E. Whang?, and Lee M. Graves* ?
*CEMALB, ?Department of Medicine, and ?Department of Pharmacology, UNC-Chapel Hill, NC27599; Human Studie...

Liposome encapsulation of curcumin and resveratrol in combination reduces prostate cancer incidence in PTEN knockout mice.

PubMed

Narayanan, Narayanan K; Nargi, Dominick; Randolph, Carla; Narayanan, Bhagavathi A

2009-07-01

Increasing interest in the use of phytochemicals to reduce prostate cancer led us to investigate 2 potential agents, curcumin and resveratrol as preventive agents. However, there is concern about the bioavailability of these agents pertinent to the poor absorption and thereby limiting its clinical use. With the view to improve their bioavailability, we used the liposome encapsulated curcumin, and resveratrol individually and in combination in male B6C3F1/J mice. Further, we examined the chemopreventive effect of liposome encapsulated curcumin and resveratrol in combination in prostate-specific PTEN knockout mice. In vitro assays using PTEN-CaP8 cancer cells were performed to investigate the combined effects curcumin with resveratrol on (i) cell growth, apoptosis and cell cycle (ii) impact on activated p-Akt, cyclin D1, m-TOR and androgen receptor (AR) proteins involved in tumor progression. HPLC analysis of serum and prostate tissues showed a significant increase in curcumin level when liposome encapsulated curcumin coadministered with liposomal resveratrol (p < 0.001). Combination of liposomal forms of curcumin and resveratrol significantly decreased prostatic adenocarcinoma in vivo (p < 0.001). In vitro studies revealed that curcumin plus resveratrol effectively inhibit cell growth and induced apoptosis. Molecular targets activated due to the loss of phosphatase and tensin homolog (PTEN) including p-Akt, cyclin D1, mammalian target of rapamycin and AR were downregulated by these agents in combination. Findings from this study for the first time provide evidence on phytochemicals in combination to enhance chemopreventive efficacy in prostate cancer. These findings clearly suggest that phytochemicals in combination may reduce prostate cancer incidence due to the loss of the tumor suppressor gene PTEN.

A miR-335/COX-2/PTEN axis regulates the secretory phenotype of senescent cancer-associated fibroblasts

PubMed Central

Kabir, Tasnuva D.; Leigh, Ross J.; Tasena, Hataitip; Mellone, Massimiliano; Coletta, Ricardo D.; Parkinson, Eric K.; Prime, Stephen S.; Thomas, Gareth J.; Paterson, Ian C.; Zhou, Donghui; McCall, John; Speight, Paul M.; Lambert, Daniel W.

2016-01-01

Senescent cancer-associated fibroblasts (CAF) develop a senescence-associated secretory phenotype (SASP) that is believed to contribute to cancer progression. The mechanisms underlying SASP development are, however, poorly understood. Here we examined the functional role of microRNA in the development of the SASP in normal fibroblasts and CAF. We identified a microRNA, miR-335, up-regulated in the senescent normal fibroblasts and CAF and able to modulate the secretion of SASP factors and induce cancer cell motility in co-cultures, at least in part by suppressing the expression of phosphatase and tensin homologue (PTEN). Additionally, elevated levels of cyclo-oxygenase 2 (PTGS2; COX-2) and prostaglandin E2 (PGE2) secretion were observed in senescent fibroblasts, and inhibition of COX-2 by celecoxib reduced the expression of miR-335, restored PTEN expression and decreased the pro-tumourigenic effects of the SASP. Collectively these data demonstrate the existence of a novel miRNA/PTEN-regulated pathway modulating the inflammasome in senescent fibroblasts. PMID:27385366

Feedback regulation on PTEN/AKT pathway by the ER stress kinase PERK mediated by interaction with the Vault complex.

PubMed

Zhang, Wei; Neo, Suat Peng; Gunaratne, Jayantha; Poulsen, Anders; Boping, Liu; Ong, Esther Hongqian; Sangthongpitag, Kanda; Pendharkar, Vishal; Hill, Jeffrey; Cohen, Stephen M

2015-03-01

The high proliferation rate of cancer cells, together with environmental factors such as hypoxia and nutrient deprivation can cause Endoplasmic Reticulum (ER) stress. The protein kinase PERK is an essential mediator in one of the three ER stress response pathways. Genetic and pharmacological inhibition of PERK has been reported to limit tumor growth in xenograft models. Here we provide evidence that inactive PERK interacts with the nuclear pore-associated Vault complex protein and that this compromises Vault-mediated nuclear transport of PTEN. Pharmacological inhibition of PERK under ER stress results is abnormal sequestration of the Vault complex, leading to increased cytoplasmic PTEN activity and lower AKT activation. As the PI3K/PTEN/AKT pathway is crucial for many aspects of cell growth and survival, this unexpected effect of PERK inhibitors on AKT activity may have implications for their potential use as therapeutic agents. Copyright © 2014. Published by Elsevier Inc.

Odontogenic ameloblast-associated protein (ODAM) inhibits growth and migration of human melanoma cells and elicits PTEN elevation and inactivation of PI3K/AKT signaling

PubMed Central

2013-01-01

Background The Odontogenic Ameloblast-associated Protein (ODAM) is expressed in a wide range of normal epithelial, and neoplastic tissues, and we have posited that ODAM serves as a novel prognostic biomarker for breast cancer and melanoma. Transfection of ODAM into breast cancer cells yields suppression of cellular growth, motility, and in vivo tumorigenicity. Herein we have extended these studies to the effects of ODAM on cultured melanoma cell lines. Methods The A375 and C8161 melanoma cell lines were stably transfected with ODAM and assayed for properties associated with tumorigenicity including cell growth, motility, and extracellular matrix adhesion. In addition, ODAM–transfected cells were assayed for signal transduction via AKT which promotes cell proliferation and survival in many neoplasms. Results ODAM expression in A375 and C8161 cells strongly inhibited cell growth and motility in vitro, increased cell adhesion to extracellular matrix, and yielded significant cytoskeletal/morphologic rearrangement. Furthermore, AKT activity was downregulated by ODAM expression while an increase was noted in expression of the PTEN (phosphatase and tensin homolog on chromosome 10) tumor suppressor gene, an antagonist of AKT activation. Increased PTEN in ODAM-expressing cells was associated with increases in PTEN mRNA levels and de novo protein synthesis. Silencing of PTEN expression yielded recovery of AKT activity in ODAM-expressing melanoma cells. Similar PTEN elevation and inhibition of AKT by ODAM was observed in MDA-MB-231 breast cancer cells while ODAM expression had no effect in PTEN-deficient BT-549 breast cancer cells. Conclusions The apparent anti-neoplastic effects of ODAM in cultured melanoma and breast cancer cells are associated with increased PTEN expression, and suppression of AKT activity. This association should serve to clarify the clinical import of ODAM expression and any role it may serve as an indicator of tumor behavior. PMID:23648148

Tumour-associated neutrophils and loss of epithelial PTEN can promote corticosteroid-insensitive MMP-9 expression in the chronically inflamed lung microenvironment

PubMed Central

Vannitamby, Amanda; Seow, Huei Jiunn; Anderson, Gary; Vlahos, Ross; Thompson, Michelle; Steinfort, Daniel; Irving, Louis B; Bozinovski, Steven

2017-01-01

Matrix metalloproteinase-9 (MMP-9) is increased in a number of pathological lung conditions, where the proteinase contributes to deleterious remodelling of the airways. While both lung cancer and COPD are associated with increased MMP-9 expression, the cellular and molecular drivers of MMP-9 remain unresolved. In this study, MMP-9 transcript measured within the tumour region from patients with non-small-cell lung cancer (NSCLC) and coexisting COPD was found to be uniformly increased relative to adjacent tumour-free tissue. MMP-9 gene expression and immunohistochemistry identified tumour-associated neutrophils, but not macrophages, as a predominant source of this proteinase. In addition, PTEN gene expression was significantly reduced in tumour and there was evidence of epithelial MMP-9 expression. To explore whether PTEN can regulate epithelial MMP-9 expression, a small interfering (si)RNA knockdown strategy was used in Beas-2B bronchial epithelial cells. PTEN knockdown by siRNA selectively increased MMP-9 expression in response to lipopolysaccharide in a corticosteroid-insensitive manner. In summary, tumour-associated neutrophils represent an important source of MMP-9 in NSCLC, and loss of epithelial PTEN may further augment steroid-insensitive expression. PMID:28202627

Impact of Prostate Inflammation on Lesion Development in the POET3+Pten+/− Mouse Model of Prostate Carcinogenesis

PubMed Central

Burcham, Grant N.; Cresswell, Gregory M.; Snyder, Paul W.; Chen, Long; Liu, Xiaoqi; Crist, Scott A.; Henry, Michael D.; Ratliff, Timothy L.

2015-01-01

Evidence linking prostatitis and prostate cancer development is contradictory. To study this link, the POET3 mouse, an inducible model of prostatitis, was crossed with a Pten-loss model of prostate cancer (Pten+/−) containing the ROSA26 luciferase allele to monitor prostate size. Prostatitis was induced, and prostate bioluminescence was tracked over 12 months, with lesion development, inflammation, and cytokine expression analyzed at 4, 8, and 12 months and compared with mice without induction of prostatitis. Acute prostatitis led to more proliferative epithelium and enhanced bioluminescence. However, 4 months after initiation of prostatitis, mice with induced inflammation had lower grade pre-neoplastic lesions. A trend existed toward greater development of carcinoma 12 months after induction of inflammation, including one of two mice with carcinoma developing perineural invasion. Two of 18 mice at the later time points developed lesions with similarities to proliferative inflammatory atrophy, including one mouse with associated carcinoma. Pten+/− mice developed spontaneous inflammation, and prostatitis was similar among groups of mice at 8 and 12 months. Analyzed as one cohort, lesion number and grade were positively correlated with prostatitis. Specifically, amounts of CD11b+Gr1+ cells were correlated with lesion development. These results support the hypothesis that myeloid-based inflammation is associated with lesion development in the murine prostate, and previous bouts of CD8-driven prostatitis may promote invasion in the Pten+/− model of cancer. PMID:25455686

Long noncoding RNA HULC accelerates liver cancer by inhibiting PTEN via autophagy cooperation to miR15a.

PubMed

Xin, Xiaoru; Wu, Mengying; Meng, Qiuyu; Wang, Chen; Lu, Yanan; Yang, Yuxin; Li, Xiaonan; Zheng, Qidi; Pu, Hu; Gui, Xin; Li, Tianming; Li, Jiao; Jia, Song; Lu, Dongdong

2018-06-12

Long noncoding RNA HULC is highly up-regulation in human hepatocellular carcinoma (HCC). However, the functions of HULC in hepatocarcinogenesis remains unclear. RT-PCR, Western blotting, Chromatin immunoprecipitation (CHIP) assay, RNA Immunoprecipitation (RIP) and tumorignesis test in vitro and in vivo were performed. HULC is negatively associated with expression of PTEN or miR15a in patients of human liver cancer. Moreover, HULC accelerates malignant progression of liver cancer cells in vitro and in vivo. Mechanistically, HULC increasesthe expression of P62 via decreasing mature miR15a. On the other hand, excessive HULC increases the expression of LC3 on the level of transcription and then activates LC3 through Sirt1 (a deacetylase). Notably, HULC enhanced the interplay between LC3 and ATG3. Furthermore, HULC also increases the expression of becline-1(autophagy related gene). Therefore, HULC increases the cellular autophagy by increasing LC3II dependent on Sirt1.Noteworthy, excessive HULC reduces the expression of PTEN, β-catenin and enhances the expression of SAPK/JUNK, PKM2, CDK2, NOTCH1, C-Jun in liver cancer cells. Of significance, our observations also revealed that HULC inhibited PTEN through ubiquitin-proteasome system mediated by autophagy-P62.Ultimately,HULC activates AKT-PI3K-mTOR pathway through inhibiting PTEN in human liver cancer cells. This study elucidates a novel mechanism that lncRNA HULC produces a vital function during hepatocarcinogenesis.

Actin cytoskeleton organization, cell surface modification and invasion rate of 5 glioblastoma cell lines differing in PTEN and p53 status

DOE Office of Scientific and Technical Information (OSTI.GOV)

Djuzenova, Cholpon S., E-mail: djuzenova_t@ukw.de; Fiedler, Vanessa; Memmel, Simon

Glioblastoma cells exhibit highly invasive behavior whose mechanisms are not yet fully understood. The present study explores the relationship between the invasion capacity of 5 glioblastoma cell lines differing in p53 and PTEN status, expression of mTOR and several other marker proteins involved in cell invasion, actin cytoskeleton organization and cell morphology. We found that two glioblastoma lines mutated in both p53 and PTEN genes (U373-MG and SNB19) exhibited the highest invasion rates through the Matrigel or collagen matrix. In DK-MG (p53wt/PTENwt) and GaMG (p53mut/PTENwt) cells, F-actin mainly occurred in the numerous stress fibers spanning the cytoplasm, whereas U87-MG (p53wt/PTENmut),more » U373-MG and SNB19 (both p53mut/PTENmut) cells preferentially expressed F-actin in filopodia and lamellipodia. Scanning electron microscopy confirmed the abundant filopodia and lamellipodia in the PTEN mutated cell lines. Interestingly, the gene profiling analysis revealed two clusters of cell lines, corresponding to the most (U373-MG and SNB19, i.e. p53 and PTEN mutated cells) and less invasive phenotypes. The results of this study might shed new light on the mechanisms of glioblastoma invasion. - Highlights: • We examine 5 glioblastoma lines on the invasion capacity and actin cytoskeleton. • Glioblastoma cell lines mutated in both p53 and PTEN were the most invasive. • Less invasive cells showed much less lamellipodia, but more actin stress fibers. • A mechanism for the differences in tumor cell invasion is proposed.« less

Membrane association of the PTEN tumor suppressor: Neutron scattering and MD simulations reveal the structure of protein-membranes complexes

PubMed Central

Nanda, Hirsh; Heinrich, Frank; Lösche, Mathias

2014-01-01

Neutron reflection (NR) from planar interfaces is an emerging technology that provides unique and otherwise inaccessible structural information on disordered molecular systems such as membrane proteins associated with fluid bilayers, thus addressing one of the remaining challenges of structural biology. Although intrinsically a low-resolution technique, using structural information from crystallography or NMR allows the construction of NR models that describe the architecture of protein-membrane complexes at high resolution. In addition, a combination of these methods with molecular dynamics (MD) simulations has the potential to reveal the dynamics of protein interactions with the bilayer in atomistic detail. We review recent advances in this area by discussing the application of these techniques to the complex formed by the PTEN phosphatase with the plasma membrane. These studies provide insights in the cellular regulation of PTEN, its interaction with PI(4,5)P2 in the inner plasma membrane and the pathway by which its substrate, PI(3,4,5)P3, accesses the PTEN catalytic site. PMID:25461777

Modulation of CASC2/miR-21/PTEN pathway sensitizes cervical cancer to cisplatin.

PubMed

Feng, Yeqian; Zou, Wen; Hu, Chunhong; Li, Guiyuan; Zhou, Shenghua; He, Yan; Ma, Fang; Deng, Chao; Sun, Lili

2017-06-01

Cisplatin (DDP) -based chemotherapy is a standard strategy for cervical cancer, while chemoresistance remains a challenge. Recent evidence highlights the crucial regulatory roles of long non-coding RNAs (lncRNA) in tumor biology. However, the roles and regulatory mechanisms of the novel lncRNA, cancer susceptibility candidate 2 (CASC2), in cervical cancer tumorigenesis and chemoresistance are poorly understood. In this study, CASC2 expression was down-regulated in cervical cancer tissues, and was related to a shorter survival time and poorer clinicopathologic features. Exogenous CACS2 alone was sufficient to inhibit cervical cancer cell proliferation and amplified DDP-induced repression of cell proliferation. A lower expression of CACS2 was observed in the DDP-resistant cervical cancer tissues, compared to DDP-sensitive cancer tissues; CACS2 overexpression could sensitize DDP-resistant cervical cancer cell (HeLa/DDP and CaSki/DDP) to DDP. Further functional experiments indicate that CASC2 upregulated PTEN expression by direct inhibiting miR-21 in the DDP-resistant cancer cells, leading to the down-regulation of p-AKT protein. In DDP-resistant cervical cancer tissues, miR-21 was up-regulated while PTEN was down-regulated. Taken together, these observations suggest CASC2 up-regulates PTEN as a ceRNA of miR-21 and plays an important role in cervical cancer sensitivity to DDP and may serve as a potential target for cancer diagnosis and treatment. Copyright © 2017 Elsevier Inc. All rights reserved.

Loss of PTEN as a Predictive Biomarker of Response to Lithium Chloride, A Potential Targeted Treatment for Breast Cancer

DTIC Science & Technology

2012-06-01

infected cells, we were unable to produce HCC712 and HCC1187 cell lines with knocked out PTEN. We hypothesize that this is due to the high level of...Growth Factor Receptor in MCF-10A human breast epithelial cells. Western blot demonstrating levels of total EGFR in parental MCF-10A, and three stably...overexpression of EGFR. We performed western blot analyses to determine the degree of MAPK and PI3K pathway activation by comparing relative levels of

Reactivation of oxidized PTP1B and PTEN by Thioredoxin 1

PubMed Central

Schwertassek, Ulla; Haque, Aftabul; Krishnan, Navasona; Greiner, Romy; Weingarten, Lars; Dick, Tobias P.; Tonks, Nicholas K.

2014-01-01

The transient inactivation of protein phosphatases contributes to the efficiency and temporal control of kinase-dependent signal transduction. In particular, members of the protein tyrosine phosphatase family are known to undergo reversible oxidation of their active site cysteine. The thiol oxidation step requires activation of co-localized NADPH oxidases and is mediated by locally produced ROS, in particular H2O2. How oxidized phosphatases are returned to the reduced active state is less well studied. Both major thiol reductive systems, the thioredoxin and the glutathione systems, have been implicated in the reactivation of phosphatases. Here, we show that the protein tyrosine phosphatase PTP1B and the dual-specificity phosphatase PTEN are preferentially reactivated by the thioredoxin system. We show that inducible depletion of TRX1 slows down PTEN re-activation in intact living cells. Finally, using a mechanism-based trapping approach we demonstrate direct thiol disulfide exchange between the active sites of thioredoxin and either phosphatase. The application of thioredoxin trapping mutants represents a complementary approach to direct assays of PTP oxidation in elucidating the significance of redox regulation of PTP function in the control of cell signaling. PMID:24976139

Superoxide anion radicals induce IGF-1 resistance through concomitant activation of PTP1B and PTEN

PubMed Central

Singh, Karmveer; Maity, Pallab; Krug, Linda; Meyer, Patrick; Treiber, Nicolai; Lucas, Tanja; Basu, Abhijit; Kochanek, Stefan; Wlaschek, Meinhard; Geiger, Hartmut; Scharffetter-Kochanek, Karin

2015-01-01

The evolutionarily conserved IGF-1 signalling pathway is associated with longevity, metabolism, tissue homeostasis, and cancer progression. Its regulation relies on the delicate balance between activating kinases and suppressing phosphatases and is still not very well understood. We report here that IGF-1 signalling in vitro and in a murine ageing model in vivo is suppressed in response to accumulation of superoxide anions () in mitochondria, either by chemical inhibition of complex I or by genetic silencing of -dismutating mitochondrial Sod2. The -dependent suppression of IGF-1 signalling resulted in decreased proliferation of murine dermal fibroblasts, affected translation initiation factors and suppressed the expression of α1(I), α1(III), and α2(I) collagen, the hallmarks of skin ageing. Enhanced led to activation of the phosphatases PTP1B and PTEN, which via dephosphorylation of the IGF-1 receptor and phosphatidylinositol 3,4,5-triphosphate dampened IGF-1 signalling. Genetic and pharmacologic inhibition of PTP1B and PTEN abrogated -induced IGF-1 resistance and rescued the ageing skin phenotype. We thus identify previously unreported signature events with , PTP1B, and PTEN as promising targets for drug development to prevent IGF-1 resistance-related pathologies. PMID:25520316

Enhancing the Effects of Low Dose Doxorubicin Treatment by the Radiation in T47D and SKBR3 Breast Cancer Cells

PubMed Central

Aghaee, Fahimeh; Baradaran, Behzad; Mesbahi, Asghar; Mohammadzadeh, Mohammad; Jafarabadi, Mohammad Asghari

2013-01-01

Purpose Breast cancer is the most common malignancy of women worldwide. Radiotherapy consists of a vital element in the treatment of breast cancer but relative side effects and different radioactive responses are limiting factors for a successful treatment. Doxorubicin has been used to treat cancers for over 30 years and is considered as the most effective drug in the treatment of breast cancer. There are also many chronic side effects that limit the amount of doxorubicin that can be administered. The combined radio-drug treatment, with low doses, can be an approach for reducing side effects from single modality treatments instead of suitable cure rates. Methods We have studied the effect of 1, 1.5, and 2 Gy doses of 9 MV X-rays along with 1 µM doxorubicin on inducing cell death, apoptosis and also p53 and PTEN gene expression in T47D and SKBR3 breast cancer cells. Results Doxorubicin treatment resulted in upregulation of radiation-induced levels of p53 and downregulation of PTEN at 1 and 1.5 Gy in T47D breast cancer cells, as well as downregulation of p53 mRNA level of expression and upregulation of PTEN mRNA level of expression in SKBR3 breast cancer cell line. In addition, doxorubicin in combination with radiation decreased the viability of breast cancer cell lines in the both cell lines. Conclusion Low doses of doxorubicin, with least cell toxicity, may be an effective treatment for breast cancer when used in conjunction with ionizing radiation. PMID:23843848

Notch-1-PTEN-ERK1/2 signaling axis promotes HER2+ breast cancer cell proliferation and stem cell survival.

PubMed

Baker, Andrew; Wyatt, Debra; Bocchetta, Maurizio; Li, Jun; Filipovic, Aleksandra; Green, Andrew; Peiffer, Daniel S; Fuqua, Suzanne; Miele, Lucio; Albain, Kathy S; Osipo, Clodia

2018-05-10

Trastuzumab targets the HER2 receptor on breast cancer cells to attenuate HER2-driven tumor growth. However, resistance to trastuzumab-based therapy remains a major clinical problem for women with HER2+ breast cancer. Breast cancer stem cells (BCSCs) are suggested to be responsible for drug resistance and tumor recurrence. Notch signaling has been shown to promote BCSC survival and self-renewal. Trastuzumab-resistant cells have increased Notch-1 expression. Notch signaling drives cell proliferation in vitro and is required for tumor recurrence in vivo. We demonstrate herein a mechanism by which Notch-1 is required for trastuzumab resistance by repressing PTEN expression to contribute to activation of ERK1/2 signaling. Furthermore, Notch-1-mediated inhibition of PTEN is necessary for BCSC survival in vitro and in vivo. Inhibition of MEK1/2-ERK1/2 signaling in trastuzumab-resistant breast cancer cells mimics effects of Notch-1 knockdown on bulk cell proliferation and BCSC survival. These findings suggest that Notch-1 contributes to trastuzumab resistance by repressing PTEN and this may lead to hyperactivation of ERK1/2 signaling. Furthermore, high Notch-1 and low PTEN mRNA expression may predict poorer overall survival in women with breast cancer. Notch-1 protein expression predicts poorer survival in women with HER2+ breast cancer. These results support a potential future clinical trial combining anti-Notch-1 and anti-MEK/ERK therapy for trastuzumab-resistant breast cancer.

Membrane Association of the PTEN Tumor Suppressor: Electrostatic Interaction with Phos-phatidylserine-Containing Bilayers and Regulatory Role of the C-Terminal Tail

PubMed Central

Shenoy, Siddharth S.; Nanda, Hirsh; Lösche, Mathias

2012-01-01

The phosphatidylinositolphosphate phosphatase PTEN is the second most frequently mutated protein in human tumors. Its membrane association, allosteric activation and membrane dissociation are poorly understood. We recently reported PTEN binding affinities to membranes of different compositions and a preliminary investigation of the protein-membrane complex with neutron reflectometry (NR). Here we use NR to validate molecular dynamics (MD) simulations of the protein and study conformational differences of the protein in solution and on anionic membranes. NR shows that full-length PTEN binds to such membranes roughly in the conformation and orientation suggested by the crystal structure of a truncated PTEN protein, in contrast with a recently presented model which suggested that membrane binding depends critically on the SUMOylation of the CBR3 loop of PTEN’s C2 domain. Our MD simulations confirm that PTEN is peripherally bound to the bilayer surface and show slight differences of the protein structure in solution and in the membrane-bound state, where the protein body flattens against the bilayer surface. PTEN’s C2 domain binds phosphatidylserine (PS) tightly through its CBR3 loop, and its phosphatase domain also forms electrostatic interactions with PS. NR and MD results show consistently that PTEN’s unstructured, anionic C-terminal tail is repelled from the bilayer surface. In contrast, this tail is tightly tugged against the C2 domain in solution, partially obstructing the membrane-binding interface of the protein. Arresting the C-terminal tail in this conformation by phosphorylation may provide a control mechanism for PTEN’s membrane binding and activity. PMID:23073177

Deregulation of the EGFR/PI3K/PTEN/Akt/mTORC1 pathway in breast cancer: possibilities for therapeutic intervention

PubMed Central

Davis, Nicole M.; Sokolosky, Melissa; Stadelman, Kristin; Abrams, Stephen L.; Libra, Massimo; Candido, Saverio; Nicoletti, Ferdinando; Polesel, Jerry; Maestro, Roberta; D’Assoro, Antonino; Drobot, Lyudmyla; Rakus, Dariusz; Gizak, Agnieszka; Laidler, Piotr; Dulińska-Litewka, Joanna; Basecke, Joerg; Mijatovic, Sanja; Maksimovic-Ivanic, Danijela; Montalto, Giuseppe; Cervello, Melchiorre; Fitzgerald, Timothy L.; Demidenko, Zoya N.; Martelli, Alberto M.; Cocco, Lucio; Steelman, Linda S.; McCubrey, James A.

2014-01-01

The EGFR/PI3K/PTEN/Akt/mTORC1/GSK-3 pathway plays prominent roles in malignant transformation, prevention of apoptosis, drug resistance and metastasis. The expression of this pathway is frequently altered in breast cancer due to mutations at or aberrant expression of: HER2, ERalpha, BRCA1, BRCA2, EGFR1, PIK3CA, PTEN, TP53, RB as well as other oncogenes and tumor suppressor genes. In some breast cancer cases, mutations at certain components of this pathway (e.g., PIK3CA) are associated with a better prognosis than breast cancers lacking these mutations. The expression of this pathway and upstream HER2 has been associated with breast cancer initiating cells (CICs) and in some cases resistance to treatment. The anti-diabetes drug metformin can suppress the growth of breast CICs and herceptin-resistant HER2+ cells. This review will discuss the importance of the EGFR/PI3K/PTEN/Akt/mTORC1/GSK-3 pathway primarily in breast cancer but will also include relevant examples from other cancer types. The targeting of this pathway will be discussed as well as clinical trials with novel small molecule inhibitors. The targeting of the hormone receptor, HER2 and EGFR1 in breast cancer will be reviewed in association with suppression of the EGFR/PI3K/PTEN/Akt/mTORC1/GSK-3 pathway. PMID:25051360

Deregulation of the EGFR/PI3K/PTEN/Akt/mTORC1 pathway in breast cancer: possibilities for therapeutic intervention.

PubMed

Davis, Nicole M; Sokolosky, Melissa; Stadelman, Kristin; Abrams, Steve L; Libra, Massimo; Candido, Saverio; Nicoletti, Ferdinando; Polesel, Jerry; Maestro, Roberta; D'Assoro, Antonino; Drobot, Lyudmyla; Rakus, Dariusz; Gizak, Agnieszka; Laidler, Piotr; Dulińska-Litewka, Joanna; Basecke, Joerg; Mijatovic, Sanja; Maksimovic-Ivanic, Danijela; Montalto, Giuseppe; Cervello, Melchiorre; Fitzgerald, Timothy L; Demidenko, Zoya; Martelli, Alberto M; Cocco, Lucio; Steelman, Linda S; McCubrey, James A

2014-07-15

The EGFR/PI3K/PTEN/Akt/mTORC1/GSK-3 pathway plays prominent roles in malignant transformation, prevention of apoptosis, drug resistance and metastasis. The expression of this pathway is frequently altered in breast cancer due to mutations at or aberrant expression of: HER2, ERalpha, BRCA1, BRCA2, EGFR1, PIK3CA, PTEN, TP53, RB as well as other oncogenes and tumor suppressor genes. In some breast cancer cases, mutations at certain components of this pathway (e.g., PIK3CA) are associated with a better prognosis than breast cancers lacking these mutations. The expression of this pathway and upstream HER2 has been associated with breast cancer initiating cells (CICs) and in some cases resistance to treatment. The anti-diabetes drug metformin can suppress the growth of breast CICs and herceptin-resistant HER2+ cells. This review will discuss the importance of the EGFR/PI3K/PTEN/Akt/mTORC1/GSK-3 pathway primarily in breast cancer but will also include relevant examples from other cancer types. The targeting of this pathway will be discussed as well as clinical trials with novel small molecule inhibitors. The targeting of the hormone receptor, HER2 and EGFR1 in breast cancer will be reviewed in association with suppression of the EGFR/PI3K/PTEN/Akt/mTORC1/GSK-3 pathway.

Translational Regulation of PTEN/MMAC1 Expression in Prostate Cancer

DTIC Science & Technology

2005-05-01

Ac reporting burden for this collection of information is estimated to average 1 hour per response , including the time for reviewing instructions... responsible for constitutive production of the PTEN mRNAs with shorter 5’-UTRs in prostate cancer cells which would be compatible for cap-dependent...LIMITATION 18. NUMBER 19a. NAME OF RESPONSIBLE PERSON OF ABSTRACT OF PAGES a. REPORT b. ABSTRACT c. THIS PAGE 19b. TELEPHONE NUMBER (include area U U U UU

Osthole inhibits the PI3K/AKT signaling pathway via activation of PTEN and induces cell cycle arrest and apoptosis in esophageal squamous cell carcinoma.

PubMed

Zhu, Xinbing; Li, Zhengzheng; Li, Tongtong; Long, Fei; Lv, Yuesheng; Liu, Lei; Liu, Xuefeng; Zhan, Qimin

2018-06-01

Esophageal squamous cell carcinoma (ESCC) is one of the most common lethal tumors and is known to be lack of effective therapy. Thus, novel therapeutic strategies are greatly needed for treatment of ESCC. Osthole, a natural active extract, has been documented to have anti-tumor activity. However, the effect of osthole on ESCC cells has not been elucidated. In this study, we demonstrated that osthole could inhibit the ESCC cell proliferation in dose- and time-dependent manner. Osthole treatment also induced G2/M phase arrest and apoptosis of ESCC cells. Furthermore, upon exposure to osthole, the expression of Cyclin B1, Cdc2, Bcl-2, PARP1 and Survivin was decreased, while the expression of BAX, cleaved PARP1, cleaved Caspase3 and cleaved Caspase9 was increased. In addition, osthole treatment elicited upregulation of PTEN and downregulation of PI3K and phosphorylated AKT (p-AKT). Taken together, our study demonstrates that osthole could suppress ESCC proliferation through inducing cell cycle arrest and apoptosis. Moreover, PTEN-PI3K/AKT signaling pathway can be regulated by osthole. Our results indicate that osthole may find therapeutic application in the treatment of ESCC patients. Copyright © 2018. Published by Elsevier Masson SAS.

Bi-phasic regulation of glycogen content in astrocytes via Cav-1/PTEN/PI3K/AKT/GSK-3β pathway by fluoxetine.

PubMed

Bai, Qiufang; Song, Dan; Gu, Li; Verkhratsky, Alexei; Peng, Liang

2017-04-01

Here, we present the data indicating that chronic treatment with fluoxetine regulates Cav-1/PTEN/PI3K/AKT/GSK-3β signalling pathway and glycogen content in primary cultures of astrocytes with bi-phasic concentration dependence. At lower concentrations, fluoxetine downregulates gene expression of Cav-1, decreases membrane content of PTEN, increases activity of PI3K/AKT, and elevates GSK-3β phosphorylation thus suppressing its activity. At higher concentrations, fluoxetine acts in an inverse fashion. As expected, fluoxetine at lower concentrations increased while at higher concentrations decreased glycogen content in astrocytes. Our findings indicate that bi-phasic regulation of glycogen content via Cav-1/PTEN/PI3K/AKT/GSK-3β pathway by fluoxetine may be responsible for both therapeutic and side effects of the drug.

Differential Expression and Clinical Significance of DNA Methyltransferase 3B (DNMT3B), Phosphatase and Tensin Homolog (PTEN) and Human MutL Homologs 1 (hMLH1) in Endometrial Carcinomas.

PubMed

Li, Wenting; Wang, Ying; Fang, Xinzhi; Zhou, Mei; Li, Yiqun; Dong, Ying; Wang, Ruozheng

2017-02-21

BACKGROUND The aim of this study was to investigate the expression and the clinicopathologic significance of DNA methyltransferase 3B (DNMT3B), phosphatase and tensin homolog (PTEN) and human MutL homologs 1 (hMLH1) in endometrial carcinomas between Han and Uygur women in Xinjiang. MATERIAL AND METHODS The expression of DNMT3B, PTEN, and hMLH1 in endometrial carcinomas were assessed by immunohistochemistry, followed by an analysis of their relationship to clinical-pathological features and prognosis. RESULTS There were a 61.7% (95/154) overexpression of DNMT3B, 50.0% (77/154) loss of PTEN expression and 18.2% (28/154) loss of hMLH1 expression. The expression of DNMT3B and PTEN in endometrial carcinomas was statistically significantly different between Uygur women and Han women (p=0.001, p=0.010, respectively). DNMT3B expression was statistically significant based on the grade of endometrial carcinomas (p=0.031). PTEN loss was statistically significant between endometrioid carcinomas (ECs) and non endometrioid carcinomas (NECs) (p=0.040). DNMT3B expression was statistically significant in different myometrial invasion groups in Uygur women (p=0.010). Furthermore, the correlation of DNMT3B and PTEN expression was significant in endometrial carcinomas (p=0.021). PTEN expression was statistically significant in the overall survival (OS) rate of women with endometrial cancers (p=0.041). CONCLUSIONS Our findings suggest that PTEN and DNMT3B possess common regulation features as well as certain ethnic differences in expression between Han women and Uygur women. An interaction may exist in the pathogenesis of endometrial carcinoma. DNMT3B was expressed differently in cases of myometrial invasion and PTEN was associated with OS, which suggested that these molecular markers may be useful in the evaluation of the biological behavior of endometrial carcinomas and may be useful indicators of prognosis in women with endometrial carcinomas.

Differential Expression and Clinical Significance of DNA Methyltransferase 3B (DNMT3B), Phosphatase and Tensin Homolog (PTEN) and Human MutL Homologs 1 (hMLH1) in Endometrial Carcinomas

PubMed Central

Li, Wenting; Wang, Ying; Fang, Xinzhi; Zhou, Mei; Li, Yiqun; Dong, Ying; Wang, Ruozheng

2017-01-01

Background The aim of this study was to investigate the expression and the clinicopathologic significance of DNA methyltransferase 3B (DNMT3B), phosphatase and tensin homolog (PTEN) and human MutL homologs 1 (hMLH1) in endometrial carcinomas between Han and Uygur women in Xinjiang. Material/Methods The expression of DNMT3B, PTEN, and hMLH1 in endometrial carcinomas were assessed by immunohistochemistry, followed by an analysis of their relationship to clinical-pathological features and prognosis. Results There were a 61.7% (95/154) overexpression of DNMT3B, 50.0% (77/154) loss of PTEN expression and 18.2% (28/154) loss of hMLH1 expression. The expression of DNMT3B and PTEN in endometrial carcinomas was statistically significantly different between Uygur women and Han women (p=0.001, p=0.010, respectively). DNMT3B expression was statistically significant based on the grade of endometrial carcinomas (p=0.031). PTEN loss was statistically significant between endometrioid carcinomas (ECs) and non endometrioid carcinomas (NECs) (p=0.040). DNMT3B expression was statistically significant in different myometrial invasion groups in Uygur women (p=0.010). Furthermore, the correlation of DNMT3B and PTEN expression was significant in endometrial carcinomas (p=0.021). PTEN expression was statistically significant in the overall survival (OS) rate of women with endometrial cancers (p=0.041). Conclusions Our findings suggest that PTEN and DNMT3B possess common regulation features as well as certain ethnic differences in expression between Han women and Uygur women. An interaction may exist in the pathogenesis of endometrial carcinoma. DNMT3B was expressed differently in cases of myometrial invasion and PTEN was associated with OS, which suggested that these molecular markers may be useful in the evaluation of the biological behavior of endometrial carcinomas and may be useful indicators of prognosis in women with endometrial carcinomas. PMID:28220037

MiR-374b Promotes Proliferation and Inhibits Apoptosis of Human GIST Cells by Inhibiting PTEN through Activation of the PI3K/Akt Pathway.

PubMed

Long, Zi-Wen; Wu, Jiang-Hong; Hong, Cai-; Wang, Ya-Nong; Zhou, Ye

2018-06-14

Gastrointestinal stromal tumours (GIST) are the most common mesenchymal tumors of the gastrointestinal (GI) tract. In order to investigate a new treatment fot GIST, we hypothesized the effect of miR-374b targeting PTEN gene-mediated PI3K/Akt signal transduction pathway on proliferation and apoptosis of human gastrointestinal stromal tumor (GIST) cells. We obtained GIST tissues and adjacent normal tissues from 143 patients with GIST to measure the levels of miR- 374b, PTEN, PI3K, Akt, caspase9, Bax, MMP2, MMP9, ki67, PCNA, P53 and cyclinD1. Finally, cell viability, cell cycle and apoptosis were detected. According to the KFGG analysis of DEGs, PTEN was involved in a variety of signaling pathways and miRs were associated with cancer development. The results showed that MiR-374b was highly expressed, while PTEN was downregulated in the GIST tissues. The levels of miR-374b, PI3K, AKT and PTEN were related to tumor diameter and pathological stage. Additionally, miR-374b increased the mRNA and protein levels of PI3K, Akt, MMP2, MMP9, P53 and cyclinD1, suggesting that miR-374b activates PI3K/Akt signaling pathway in GIST-T1 cells. Moreover, MiR- 374b promoted cell viability, migration, invasion, and cell cycle entry, and inhibited apoptosis in GIST cells. Taken together, the results indicated that miR-374b promotes viability and inhibits apoptosis of human GIST cells by targeting PTEN gene through the PI3K/Akt signaling pathway. Thus, this study provides a new potential target for GIST treatment.

Tau and PTEN status as predictive markers for response to trastuzumab and paclitaxel in patients with HER2-positive breast cancer.

PubMed

Koo, Dong-Hoe; Lee, Hee Jin; Ahn, Jin-Hee; Yoon, Dok Hyun; Kim, Sung-Bae; Gong, Gyungyub; Son, Byung Ho; Ahn, Sei Hyun; Jung, Kyung Hae

2015-08-01

Trastuzumab (H)-based chemotherapy has been an active treatment in patients with HER2-positive breast cancer; however, primary and secondary resistance has occurred in patients treated with H alone or in combination with chemotherapy. Biomarkers were searched using tissue microarrays (TMA) in HER2-positive advanced breast cancer patients treated with H and paclitaxel (P) combination chemotherapy between October 2004 and August 2010. Tumor blocks were analyzed for Tau-protein, beta-III tubulin, PTEN, p27, IGF-1R, c-Met, CD44, and MUC4 by immunohistochemical (IHC) analysis. The correlation between IHC status and clinical outcomes, including response rate (RR), progression free survival (PFS), and overall survival (OS), was investigated. With a median follow-up duration of 54.1 months (range, 42.3-72.7 months), 65 patients received H + P chemotherapy. The overall RR was 63 % (95 % CI, 51-75 %), and seven patients (11 %) with high Tau/low PTEN expression showed a significantly lower RR (14 % vs. 69 %; p = 0.008). The odds ratio for a poor response was 13.3 (95 % CI, 1.5-119.0; p = 0.020). In addition, patients with high Tau/low PTEN showed a trend of poor survival in terms of PFS (6.6 months vs. 9.6 months, p = 0.052). Subsequent multivariate analysis showed that high Tau/low PTEN (hazard ratio [HR] 2.40, 95 % CI, 1.06-5.47; p = 0.037) was the poor prognostic factor independently associated with PFS after adjusting for possible confounding factors such as recurrence/metastasis, age, performance status, visceral metastasis, and hormone receptor status. High Tau-protein and low PTEN expression showed a significant association with poor response to H + P chemotherapy in patients with HER2-positive advanced breast cancer.

Characterization of PD-L1 expression in Chinese non-small cell lung cancer patients with PTEN expression as a means for tissue quality screening.

PubMed

Zhang, Xu-Chao; Cao, Xu; Sun, Chun; Xie, Zhi; Guo, Jian-Jun; Yang, Jin-Ji; Yang, Xue-Ning; Dai, Hang-Jun; Li, Su-Chun; Xu, Xin-Ran; Zuo, Yun-Xia; Chen, Meng; Koeppen, Hartmut; He, Jing; Kiermaier, Astrid; Shames, David; Cheng, Gang; Wu, Yi-Long

2018-03-01

The goal of this study is to evaluate PD-L1 prevalence and its association with major clinical characteristics in Chinese non-small cell lung cancer (NSCLC) patients to inform the clinical development of anti-PD1/PD-L1 agents in this population. We used phosphatase and tensin homolog (PTEN) expression through IHC as a surrogate tissue quality marker to screen surgical NSCLC samples in tissue microarray (TMA; 172 cases) or whole-section (268 cases) format. The samples were then analyzed with a clinically validated PD-L1 IHC assay. The results were correlated with baseline characteristics and clinical outcomes. PTEN IHC showed that 108 TMA samples and 105 whole-section samples qualified for PD-L1 IHC. With a clinically relevant cutoff, 41.7% of the TMA samples were PD-L1 positive. PD-L1 level was much lower in EGFR-mutant patients and seemed to be a favorable prognostic factor for both overall survival (OS) and recurrence-free survival (RFS). These findings were confirmed in the whole-section samples except that their survival data were not mature enough for correlation analysis. In summary, PD-L1 expression was detected in approximately 40% of PTEN-qualified Chinese NSCLC samples, negatively correlated with EGFR mutation and seemed to be a favorable prognostic factor for both OS and RFS. Notably, the different results from PTEN-qualified and PTEN-disqualified samples underscore the importance of tissue quality control prior to biomarker testing.

Upregulation of MiR-205 transcriptionally suppresses SMAD4 and PTEN and contributes to human ovarian cancer progression

PubMed Central

Li, Juanni; Hu, Kuan; Gong, Guanghui; Zhu, Ding; Wang, Yixuan; Liu, Hailing; Wu, Xiaoying

2017-01-01

MicroRNAs (miRNAs) function as critical regulators of gene expression and their deregulation is associated with the development and progression of various cancers. This study aimed to investigate the biological role and mechanism of miR-205 in ovarian cancer (OC). MiR-205 was upregulated in OC tissues and cells in comparison to the controls. Meanwhile, overexpression of miR-205 was significantly associated with poor overall survival of OC patients. Functional study indicated that ectopic expression of miR-205 significantly promoted cell proliferation, migration, invasion and chemoresistance of OC cells. SMAD4 and PTEN were identified as direct targets of miR-205 using luciferase reporter assays, real-time PCR (qRT-PCR), and western blot. Most interestingly, in vivo studies indicated that miR-205 markedly promoted the growth and metastasis of tumors and the expression of miR-205 was also found to be inversely correlated with that of SMAD4 and PTEN in nude mice. Overall, we suggest that miR-205 functions as an oncogenic miRNA by directly binding to SMAD4 and PTEN, providing a novel target for the molecular treatment of ovarian cancer. PMID:28145479

The mitogen-activated protein kinase (MAPK) cascade controls phosphatase and tensin homolog (PTEN) expression through multiple mechanisms.

PubMed

Ciuffreda, Ludovica; Di Sanza, Cristina; Cesta Incani, Ursula; Eramo, Adriana; Desideri, Marianna; Biagioni, Francesca; Passeri, Daniela; Falcone, Italia; Sette, Giovanni; Bergamo, Paola; Anichini, Andrea; Sabapathy, Kanaga; McCubrey, James A; Ricciardi, Maria Rosaria; Tafuri, Agostino; Blandino, Giovanni; Orlandi, Augusto; De Maria, Ruggero; Cognetti, Francesco; Del Bufalo, Donatella; Milella, Michele

2012-06-01

The mitogen-activated protein kinase (MAPK) and PI3K pathways are regulated by extensive crosstalk, occurring at different levels. In tumors, transactivation of the alternate pathway is a frequent "escape" mechanism, suggesting that combined inhibition of both pathways may achieve synergistic antitumor activity. Here we show that, in the M14 melanoma model, simultaneous inhibition of both MEK and mammalian target of rapamycin (mTOR) achieves synergistic effects at suboptimal concentrations, but becomes frankly antagonistic in the presence of relatively high concentrations of MEK inhibitors. This observation led to the identification of a novel crosstalk mechanism, by which either pharmacologic or genetic inhibition of constitutive MEK signaling restores phosphatase and tensin homolog (PTEN) expression, both in vitro and in vivo, and inhibits downstream signaling through AKT and mTOR, thus bypassing the need for double pathway blockade. This appears to be a general regulatory mechanism and is mediated by multiple mechanisms, such as MAPK-dependent c-Jun and miR-25 regulation. Finally, PTEN upregulation appears to be a major effector of MEK inhibitors' antitumor activity, as cancer cells in which PTEN is inactivated are consistently more resistant to the growth inhibitory and anti-angiogenic effects of MEK blockade.

Regulation of PI 3-K, PTEN, p53, and mTOR in Malignant and Benign Tumors Deficient in Tuberin

PubMed Central

Yadav, Anamika; Mahimainathan, Lenin; Valente, Anthony J.

2011-01-01

The tuberous sclerosis complex (TSC) is caused by mutation in either of 2 tumor suppressor genes, TSC-1 (encodes hamartin) and TSC-2 (encodes tuberin). In humans, deficiency in TSC1/2 is associated with benign tumors in many organs, including renal angiomyolipoma (AML) but rarely renal cell carcinoma (RCC). In contrast, deficiency of TSC function in the Eker rat is associated with RCC. Here, we have investigated the activity of PI 3-K and the expression of PTEN, p53, tuberin, p-mTOR, and p-p70S6K in both Eker rat RCC and human renal AML. Compared to normal tissue, increased PI 3-K activity was detected in RCC of Eker rats but not in human AML tissue. In contrast, PTEN was highly expressed in AML but significantly reduced in the renal tumors of Eker rats. Phosphorylation on Ser2448 of mTOR and Thr389 of p70S6K were significantly increased in both RCC and AML compared to matching control tissue. Total tuberin was significantly decreased in AML while completely lost in RCC of Eker rats. Our data also show that while p53 protein expression is lost in rat RCC, it was highly elevated in AML. These novel data provide evidence that loss of TSC-2, PTEN, and p53 as well as activation of PI 3-K and mTOR is associated with kidney cancer in the Eker rat, while sustained expression of TSC-2, PTEN, and p53 may prevent progression of kidney cancer in TSC patients. PMID:22737271

Tumour-associated neutrophils and loss of epithelial PTEN can promote corticosteroid-insensitive MMP-9 expression in the chronically inflamed lung microenvironment.

PubMed

Vannitamby, Amanda; Seow, Huei Jiunn; Anderson, Gary; Vlahos, Ross; Thompson, Michelle; Steinfort, Daniel; Irving, Louis B; Bozinovski, Steven

2017-12-01

Matrix metalloproteinase-9 (MMP-9) is increased in a number of pathological lung conditions, where the proteinase contributes to deleterious remodelling of the airways. While both lung cancer and COPD are associated with increased MMP-9 expression, the cellular and molecular drivers of MMP-9 remain unresolved. In this study, MMP-9 transcript measured within the tumour region from patients with non-small-cell lung cancer (NSCLC) and coexisting COPD was found to be uniformly increased relative to adjacent tumour-free tissue. MMP-9 gene expression and immunohistochemistry identified tumour-associated neutrophils, but not macrophages, as a predominant source of this proteinase. In addition, PTEN gene expression was significantly reduced in tumour and there was evidence of epithelial MMP-9 expression. To explore whether PTEN can regulate epithelial MMP-9 expression, a small interfering (si)RNA knockdown strategy was used in Beas-2B bronchial epithelial cells. PTEN knockdown by siRNA selectively increased MMP-9 expression in response to lipopolysaccharide in a corticosteroid-insensitive manner. In summary, tumour-associated neutrophils represent an important source of MMP-9 in NSCLC, and loss of epithelial PTEN may further augment steroid-insensitive expression. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

Phosphatase and Tensin Homolog Deleted on Chromosome 10 (PTEN) Signaling Regulates Mitochondrial Biogenesis and Respiration via Estrogen-related Receptor α (ERRα)*

PubMed Central

Li, Yang; He, Lina; Zeng, Ni; Sahu, Divya; Cadenas, Enrique; Shearn, Colin; Li, Wei; Stiles, Bangyan L.

2013-01-01

Mitochondrial abnormalities are associated with cancer development, yet how oncogenic signals affect mitochondrial functions has not been fully understood. In this study, we investigate the relationship between mitochondrial alterations and PI3K/protein kinase B (AKT) signaling activation using hepatocytes and liver tissues as our experimental models. We show here that liver-specific deletion of Pten, which leads to activation of PI3K/AKT, is associated with elevated oxidative stress, increased mitochondrial mass, and augmented respiration accompanied by enhanced glycolysis. Consistent with these observations, estrogen-related receptor α (ERRα), an orphan nuclear receptor known for its role in mitochondrial biogenesis, is up-regulated in the absence of phosphatase and tensin homolog deleted on chromosome 10 (PTEN). Our pharmacological and genetic studies show that PI3K/AKT activity regulates the expression of ERRα and mitochondrial biogenesis/respiration. Furthermore, cAMP-response element-binding protein, as a downstream target of AKT, plays a role in the regulation of ERRα, independent of PKA signaling. ERRα regulates reactive oxygen species production, and ERRα knockdown attenuates proliferation and colony-forming potential in Pten-null hepatocytes. Finally, analysis of clinical datasets from liver tissues showed a negative correlation between expressions of ERRα and PTEN in patients with liver cancer. Therefore, this study has established a previously unrecognized link between a growth signal and mitochondrial metabolism. PMID:23836899

Prevalence of NRAS, PTEN and AKT1 gene mutations in the central nervous system metastases of non-small cell lung cancer.

PubMed

Nicoś, Marcin; Krawczyk, Paweł; Jarosz, Bożena; Sawicki, Marek; Trojanowski, Tomasz; Milanowski, Janusz

2017-01-01

Somatic mutations in NRAS, PTEN and AKT1 genes are rarely (~1%) reported in primary NSCLC, but their role in carcinogenesis have been proven. Therefore, we assessed the frequency of them in 145 FFPE tissue samples from CNS metastases of NSCLC using the real-time PCR technique. We identified four (two NRAS and single AKT1 and PTEN) mutations in CNS metastases of NSCLC. All mutations were observed in current male smokers (4% out of the male group; 4/100 and 4.25% out of smokers; 4/94). Three mutations have been detected in patients with SqCC (10.3% out of SqCC patients; 3/29), and only one mutation in the NRAS gene-in a patient with adenocarcinoma (1.25% out of AC patients; 1/80). The examined genes were mutually exclusive in terms of molecular background in KRAS; EGFR; DDR2; PIK3CA; HER2 and MEK1 genes that were evaluated in our previous studies. The OS of the patients who harbored NRAS, AKT1 and PTEN mutations was 10.1, 12.1, 7.3 and 4 months, respectively (vs 13.5 months of the studied group). Our results suggest that the presence of NRAS, PTEN and AKT1 gene mutations may have an influence on the occurrence of CNS metastases in patients with SqCC.

Involvement of phosphoinositide 3-kinase and PTEN protein in mechanism of activation of TRPC6 protein in vascular smooth muscle cells.

PubMed

Monet, Michaël; Francoeur, Nancy; Boulay, Guylain

2012-05-18

TRPC6 is a cation channel in the plasma membrane that plays a role in Ca(2+) entry after the stimulation of a G(q)-protein-coupled or tyrosine-kinase receptor. TRPC6 translocates to the plasma membrane upon stimulation and remains there as long as the stimulus is present. However, the mechanism that regulates the trafficking and activation of TRPC6 are unclear. In this study we showed phosphoinositide 3-kinase and its antagonistic phosphatase, PTEN, are involved in the activation of TRPC6. The inhibition of PI3K by PIK-93, LY294002, or wortmannin decreased carbachol-induced translocation of TRPC6 to the plasma membrane and carbachol-induced net Ca(2+) entry into T6.11 cells. Conversely, a reduction of PTEN expression did not affect carbachol-induced externalization of TRPC6 but increased Ca(2+) entry through TRPC6 in T6.11 cells. We also showed that the PI3K/PTEN pathway regulates vasopressin-induced translocation of TRPC6 to the plasma membrane and vasopressin-induced Ca(2+) entry into A7r5 cells, which endogenously express TRPC6. In summary, we provided evidence that the PI3K/PTEN pathway plays an important role in the translocation of TRPC6 to the plasma membrane and may thus have a significant impact on Ca(2+) signaling in cells that endogenously express TRPC6.

Tumor-derived CXCL8 signaling augments stroma-derived CCL2-promoted proliferation and CXCL12-mediated invasion of PTEN-deficient prostate cancer cells

PubMed Central

Maxwell, Pamela J.; Neisen, Jessica; Messenger, Johanna; Waugh, David J.J.

2014-01-01

Impaired PTEN function is a genetic hallmark of aggressive prostate cancers (CaP) and is associated with increased CXCL8 expression and signaling. The current aim was to further characterize biological responses and mechanisms underpinning CXCL8-promoted progression of PTEN-depleted prostate cancer, focusing on characterizing the potential interplay between CXCL8 and other disease-promoting chemokines resident within the prostate tumor microenvironment. Autocrine CXCL8-stimulation (i) increased expression of CXCR1 and CXCR2 in PTEN-deficient CaP cells suggesting a self-potentiating signaling axis and (ii) induced expression of CXCR4 and CCR2 in PTEN-wild-type and PTEN-depleted CaP cells. In contrast, paracrine CXCL8 signaling induced expression and secretion of the chemokines CCL2 and CXCL12 from prostate stromal WPMY-1 fibroblasts and monocytic macrophage-like THP-1 cells. In vitro studies demonstrated functional co-operation of tumor-derived CXCL8 with stromal-derived chemokines. CXCL12-induced migration of PC3 cells and CCL2-induced proliferation of prostate cancer cells were dependent upon intrinsic CXCL8 signaling within the prostate cancer cells. For example, in co-culture experiments, CXCL12/CXCR4 signaling but not CCL2/CCR2 signaling supported fibroblast-mediated migration of PC3 cells while CXCL12/CXCR4 and CCL2/CCR2 signaling underpinned monocyte-enhanced migration of PC3 cells. Combined inhibition of both CXCL8 and CXCL12 signaling was more effective in inhibiting fibroblast-promoted cell motility while repression of CXCL8 attenuated CCL2-promoted proliferation of prostate cancer cells. We conclude that tumor-derived CXCL8 signaling from PTEN-deficient tumor cells increases the sensitivity and responsiveness of CaP cells to stromal chemokines by concurrently upregulating receptor expression in cancer cells and inducing stromal chemokine synthesis. Combined chemokine targeting may be required to inhibit their multi-faceted actions in promoting the

Reciprocal feedback regulation of PI3K and androgen receptor signaling in PTEN-deficient prostate cancer.

PubMed

Carver, Brett S; Chapinski, Caren; Wongvipat, John; Hieronymus, Haley; Chen, Yu; Chandarlapaty, Sarat; Arora, Vivek K; Le, Carl; Koutcher, Jason; Scher, Howard; Scardino, Peter T; Rosen, Neal; Sawyers, Charles L

2011-05-17

Prostate cancer is characterized by its dependence on androgen receptor (AR) and frequent activation of PI3K signaling. We find that AR transcriptional output is decreased in human and murine tumors with PTEN deletion and that PI3K pathway inhibition activates AR signaling by relieving feedback inhibition of HER kinases. Similarly, AR inhibition activates AKT signaling by reducing levels of the AKT phosphatase PHLPP. Thus, these two oncogenic pathways cross-regulate each other by reciprocal feedback. Inhibition of one activates the other, thereby maintaining tumor cell survival. However, combined pharmacologic inhibition of PI3K and AR signaling caused near-complete prostate cancer regressions in a Pten-deficient murine prostate cancer model and in human prostate cancer xenografts, indicating that both pathways coordinately support survival. Copyright © 2011 Elsevier Inc. All rights reserved.

Ursolic Acid Attenuates Diabetic Mesangial Cell Injury through the Up-Regulation of Autophagy via miRNA-21/PTEN/Akt/mTOR Suppression

PubMed Central

Lu, Xinxing; Fan, Qiuling; Xu, Li; Li, Lin; Yue, Yuan; Xu, Yanyan; Su, Yan; Zhang, Dongcheng; Wang, Lining

2015-01-01

Objective To investigate the effect of ursolic acid on autophagy mediated through the miRNA-21-targeted phosphoinositide 3 kinase (PI3K)/protein kinase B (Akt)/mammalian target of rapamycin (mTOR) pathway in rat mesangial cells cultured under high glucose (HG) conditions. Methods Rat glomerular mesangial cells were cultured under normal glucose, HG, HG with the PI3K inhibitor LY294002 or HG with ursolic acid conditions. Cell proliferation and hypertrophy were assayed using an MTT assay and the ratio of total protein to cell number, respectively. The miRNA-21 expression was detected using RT-qPCR. The expression of phosphatase and tensin homolog (PTEN)/AKT/mTOR signaling signatures, autophagy-associated protein and collagen I was detected by western blotting and RT-qPCR. Autophagosomes were observed using electron microscopy. Results Compared with mesangial cells cultured under normal glucose conditions, the cells exposed to HG showed up-regulated miRNA-21 expression, down-regulated PTEN protein and mRNA expression, up-regulated p85PI3K, pAkt, pmTOR, p62/SQSTMI, and collagen I expression and down-regulated LC3II expression. Ursolic acid and LY294002 inhibited HG-induced mesangial cell hypertrophy and proliferation, down-regulated p85PI3K, pAkt, pmTOR, p62/SQSTMI, and collagen I expression and up-regulated LC3II expression. However, LY294002 did not affect the expression of miRNA-21 and PTEN. Ursolic acid down-regulated miRNA-21 expression and up-regulated PTEN protein and mRNA expression. Conclusions Ursolic acid inhibits the glucose-induced up-regulation of mesangial cell miRNA-21 expression, up-regulates PTEN expression, inhibits the activation of PI3K/Akt/mTOR signaling pathway, and enhances autophagy to reduce the accumulation of the extracellular matrix and ameliorate cell hypertrophy and proliferation. PMID:25689721

Conditional Loss of Pten in Myogenic Progenitors Leads to Postnatal Skeletal Muscle Hypertrophy but Age-Dependent Exhaustion of Satellite Cells.

PubMed

Yue, Feng; Bi, Pengpeng; Wang, Chao; Li, Jie; Liu, Xiaoqi; Kuang, Shihuan

2016-11-22

Skeletal muscle stem cells (satellite cells [SCs]) are normally maintained in a quiescent (G 0 ) state. Muscle injury not only activates SCs locally, but also alerts SCs in distant uninjured muscles via circulating factors. The resulting G Alert SCs are adapted to regenerative cues and regenerate injured muscles more efficiently, but whether they provide any long-term benefits to SCs is unknown. Here, we report that embryonic myogenic progenitors lacking the phosphatase and tensin homolog (Pten) exhibit enhanced proliferation and differentiation, resulting in muscle hypertrophy but fewer SCs in adult muscles. Interestingly, Pten null SCs are predominantly in the G Alert state, even in the absence of an injury. The G Alert SCs are deficient in self-renewal and subjected to accelerated depletion during regeneration and aging and fail to repair muscle injury in old mice. Our findings demonstrate a key requirement of Pten in G 0 entry of SCs and provide functional evidence that prolonged G Alert leads to stem cell depletion and regenerative failure. Copyright © 2016 The Author(s). Published by Elsevier Inc. All rights reserved.

Crystal structure of the cytoplasmic phosphatase and tensin homolog (PTEN)-like region of Ciona intestinalis voltage-sensing phosphatase provides insight into substrate specificity and redox regulation of the phosphoinositide phosphatase activity.

PubMed

Matsuda, Makoto; Takeshita, Kohei; Kurokawa, Tatsuki; Sakata, Souhei; Suzuki, Mamoru; Yamashita, Eiki; Okamura, Yasushi; Nakagawa, Atsushi

2011-07-01

Ciona intestinalis voltage-sensing phosphatase (Ci-VSP) has a transmembrane voltage sensor domain and a cytoplasmic region sharing similarity to the phosphatase and tensin homolog (PTEN). It dephosphorylates phosphatidylinositol 4,5-bisphosphate and phosphatidylinositol 3,4,5-trisphosphate upon membrane depolarization. The cytoplasmic region is composed of a phosphatase domain and a putative membrane interaction domain, C2. Here we determined the crystal structures of the Ci-VSP cytoplasmic region in three distinct constructs, wild-type (248-576), wild-type (236-576), and G365A mutant (248-576). The crystal structure of WT-236 and G365A-248 had the disulfide bond between the catalytic residue Cys-363 and the adjacent residue Cys-310. On the other hand, the disulfide bond was not present in the crystal structure of WT-248. These suggest the possibility that Ci-VSP is regulated by reactive oxygen species as found in PTEN. These structures also revealed that the conformation of the TI loop in the active site of the Ci-VSP cytoplasmic region was distinct from the corresponding region of PTEN; Ci-VSP has glutamic acid (Glu-411) in the TI loop, orienting toward the center of active site pocket. Mutation of Glu-411 led to acquirement of increased activity toward phosphatidylinositol 3,5-bisphosphate, suggesting that this site is required for determining substrate specificity. Our results provide the basic information of the enzymatic mechanism of Ci-VSP.

PTP1B promotes aggressiveness of breast cancer cells by regulating PTEN but not EMT.

PubMed

Liu, Xue; Chen, Qian; Hu, Xu-Gang; Zhang, Xian-Chao; Fu, Ti-Wei; Liu, Qing; Liang, Yan; Zhao, Xi-Long; Zhang, Xia; Ping, Yi-Fang; Bian, Xiu-Wu

2016-10-01

Metastasis is a complicated, multistep process and remains the major cause of cancer-related mortality. Exploring the molecular mechanisms underlying tumor metastasis is crucial for development of new strategies for cancer prevention and treatment. In this study, we found that protein tyrosine phosphatase 1B (PTP1B) promoted breast cancer metastasis by regulating phosphatase and tensin homolog (PTEN) but not epithelial-mesenchymal transition (EMT). By detecting PTP1B expression of the specimens from 128 breast cancer cases, we found that the level of PTP1B was higher in breast cancer tissues than the corresponding adjacent normal tissues. Notably, PTP1B was positively associated with lymph node metastasis (LNM) and estrogen receptor (ER) status. In vitro, disturbing PTP1B expression obviously attenuated cell migration and invasion. On the contrary, PTP1B overexpression significantly increased migration and invasion of breast cancer cells. Mechanistically, PTP1B knockdown upregulated PTEN, accompanied with an abatement of AKT phosphorylation and the expression of matrix metalloproteinase 2 (MMP2) and MMP7. Conversely, forced expression of PTP1B reduced PTEN and increased AKT phosphorylation as well as the expression of MMP2 and MMP7. Notably, neither EMT nor stemness of breast cancer cells was regulated by PTP1B. We also found that PTP1B acted as an independent prognostic factor and predicted poor prognosis in ER-positive breast cancer patients. Taken together, our findings provide advantageous evidence for the development of PTP1B as a potential therapeutic target for breast cancer, especially for ER-positive breast cancer patients.

Involvement of Phosphoinositide 3-Kinase and PTEN Protein in Mechanism of Activation of TRPC6 Protein in Vascular Smooth Muscle Cells*

PubMed Central

Monet, Michaël; Francoeur, Nancy; Boulay, Guylain

2012-01-01

TRPC6 is a cation channel in the plasma membrane that plays a role in Ca2+ entry after the stimulation of a Gq-protein-coupled or tyrosine-kinase receptor. TRPC6 translocates to the plasma membrane upon stimulation and remains there as long as the stimulus is present. However, the mechanism that regulates the trafficking and activation of TRPC6 are unclear. In this study we showed phosphoinositide 3-kinase and its antagonistic phosphatase, PTEN, are involved in the activation of TRPC6. The inhibition of PI3K by PIK-93, LY294002, or wortmannin decreased carbachol-induced translocation of TRPC6 to the plasma membrane and carbachol-induced net Ca2+ entry into T6.11 cells. Conversely, a reduction of PTEN expression did not affect carbachol-induced externalization of TRPC6 but increased Ca2+ entry through TRPC6 in T6.11 cells. We also showed that the PI3K/PTEN pathway regulates vasopressin-induced translocation of TRPC6 to the plasma membrane and vasopressin-induced Ca2+ entry into A7r5 cells, which endogenously express TRPC6. In summary, we provided evidence that the PI3K/PTEN pathway plays an important role in the translocation of TRPC6 to the plasma membrane and may thus have a significant impact on Ca2+ signaling in cells that endogenously express TRPC6. PMID:22493444

PTEN loss and chromosome 8 alterations in Gleason grade 3 prostate cancer cores predicts the presence of un-sampled grade 4 tumor: implications for active surveillance.

PubMed

Trock, Bruce J; Fedor, Helen; Gurel, Bora; Jenkins, Robert B; Knudsen, B S; Fine, Samson W; Said, Jonathan W; Carter, H Ballentine; Lotan, Tamara L; De Marzo, Angelo M

2016-07-01

Men who enter active surveillance because their biopsy exhibits only Gleason grade 3 (G3) frequently have higher grade tumor missed by biopsy. Thus, biomarkers are needed that, when measured on G3 tissue, can predict the presence of higher grade tumor in the whole prostate. We evaluated whether PTEN loss, chromosome 8q gain (MYC) and/or 8p loss (LPL) measured only on G3 cores is associated with un-sampled G4 tumor. A tissue microarray was constructed of prostatectomy tissue from patients whose prostates exhibited only Gleason score 3+3, only 3+4 or only 4+3 tumor (n=50 per group). Cores sampled only from areas of G3 were evaluated for PTEN loss by immunohistochemistry, and PTEN deletion, LPL/8p loss and MYC/8q gain by fluorescence in situ hybridization. Biomarker results were compared between Gleason score 6 vs 7 tumors using conditional logistic regression. PTEN protein loss, odds ratio=4.99, P=0.033; MYC/8q gain, odds ratio=5.36, P=0.010; and LPL/8p loss, odds ratio=3.96, P=0.003 were significantly more common in G3 cores derived from Gleason 7 vs Gleason 6 tumors. PTEN gene deletion was not statistically significant. Associations were stronger comparing Gleason 4+3 vs 6 than for Gleason 3+4 vs 6. MYC/8q gain, LPL/8p loss and PTEN protein loss measured in G3 tissue microarray cores strongly differentiate whether the core comes from a Gleason 6 or Gleason 7 tumor. If validated to predict upgrading from G3 biopsy to prostatectomy these biomarkers could reduce the likelihood of enrolling high-risk men and facilitate safe patient selection for active surveillance.

[The miR-21 attenuates hepatocyte hypoxia/reoxygenation injury via inhibiting PTEN/PI3K/AKT signaling pathway].

PubMed

Lu, Xiuxian; Sun, Chao; Zheng, Daofeng; Liu, Rui; Wei, Xufu; Wu, Zhongjun

2017-04-01

Objective To study the effect of microRNA-21 (miR-21) on hypoxia/reoxygenation (H/R)-treated primary hepatocytes from C57BL/6J mice and analyze its possible molecular mechanism. Methods The H/R model of primary hepatocytes was established and the expression of miR-21 was detected by the quantitative real-time PCR. Western blotting was used to detect protein expression levels of phosphatase and tension homology deleted on chromosome 10 (PTEN), phosphorylated AKT (p-AKT), Bcl-2 and Bax. Flow cytometry was performed to observe the hepatocyte apoptosis. Results The expression of miR-21 in primary hepatocytes decreased after H/R injury. After transfected with exogenous miR-21 mimics, the expression of PTEN decreased, while the expressions of p-AKT and Bcl-2 and the ratio of Bcl-2/Bax increased in hepatocytes; the apoptotic level of hepatocytes was downregulated. The inhibition of AKT phosphorylation could downregulate the expression of Bcl-2 and the ratio of Bcl-2/Bax, and upregulate the level of hepatocyte apoptosis. Conclusion The miR-21 can alleviate the hepatocyte apoptosis by inhibiting the PTEN/PI3K/AKT signaling pathway in the process of H/R.

Ligand-activated PPARδ inhibits UVB-induced senescence of human keratinocytes via PTEN-mediated inhibition of superoxide production.

PubMed

Ham, Sun Ah; Hwang, Jung Seok; Yoo, Taesik; Lee, Hanna; Kang, Eun Sil; Park, Chankyu; Oh, Jae-Wook; Lee, Hoon Taek; Min, Gyesik; Kim, Jin-Hoi; Seo, Han Geuk

2012-05-15

UV radiation-mediated photodamage to the skin has been implicated in premature aging and photoaging-related skin cancer and melanoma. Little is known about the cellular events that underlie premature senescence, or how to impede these events. In the present study we demonstrate that PPARδ (peroxisome-proliferator-activated receptor δ) regulates UVB-induced premature senescence of normal keratinocytes. Activation of PPARδ by GW501516, a specific ligand of PPARδ, significantly attenuated UVB-mediated generation of ROS (reactive oxygen species) and suppressed senescence of human keratinocytes. Ligand-activated PPARδ up-regulated the expression of PTEN (phosphatase and tensin homologue deleted on chromosome 10) and suppressed the PI3K (phosphatidylinositol 3-kinase)/Akt pathway. Concomitantly, translocation of Rac1 to the plasma membrane, which leads to the activation of NADPH oxidases and generation of ROS, was significantly attenuated. siRNA (small interfering RNA)-mediated knockdown of PTEN abrogated the effects of PPARδ on cellular senescence, on PI3K/Akt/Rac1 signalling and on generation of ROS in keratinocytes exposed to UVB. Finally, when HR-1 hairless mice were treated with GW501516 before exposure to UVB, the number of senescent cells in the skin was significantly reduced. Thus ligand-activated PPARδ confers resistance to UVB-induced cellular senescence by up-regulating PTEN and thereby modulating PI3K/Akt/Rac1 signalling to reduce ROS generation in keratinocytes.

Genetic disruption of Pten in a novel mouse model of tomaculous neuropathy

PubMed Central

Goebbels, Sandra; Oltrogge, Jan H; Wolfer, Susanne; Wieser, Georg L; Nientiedt, Tobias; Pieper, Alexander; Ruhwedel, Torben; Groszer, Matthias; Sereda, Michael W; Nave, Klaus-Armin

2012-01-01

‘Tomacula’ and myelin outfoldings are striking neuropathological features of a diverse group of inherited demyelinating neuropathies. Whereas the underlying genetic defects are well known, the molecular mechanisms of tomacula formation have remained obscure. We hypothesized that they are caused by uncontrolled, excessive myelin membrane growth, a process, which is regulated in normal development by neuregulin-1/ErbB2, PI3 Kinase signalling and ERK/MAPK signalling. Here, we demonstrate by targeted disruption of Pten in Schwann cells that hyperactivation of the endogenous PI3 Kinase pathway causes focal hypermyelination, myelin outfoldings and tomacula, even when induced in adult animals by tamoxifen, and is associated with progressive peripheral neuropathy. Activated AKT kinase is associated with PtdIns(3,4,5)P3 at paranodal loops and Schmidt–Lanterman incisures. This striking myelin pathology, with features of human CMT type 4B1 and HNPP, is dependent on AKT/mTOR signalling, as evidenced by a significant amelioration of the pathology in mice treated with rapamycin. We suggest that regions of non-compact myelin are under lifelong protection by PTEN against abnormal membrane outgrowth, and that dysregulated phosphoinositide levels play a critical role in the pathology of tomaculous neuropathies. PMID:22488882

miR-18a promotes cell proliferation of esophageal squamous cell carcinoma cells by increasing cylin D1 via regulating PTEN-PI3K-AKT-mTOR signaling axis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Weiguo, E-mail: weiguozhangHU@gmail.com; Lei, Caipeng; Fan, Junli

Esophageal squamous cell carcinoma (ESCC) is one of the lethal cancers with a high incidence rate in Asia. Cyclin D1 is overexpressed and plays an important role in the carcinogenesis of ESCC; however the mechanism of the deregulation of Cyclin D1 in ESCC remains to be determined. In the study, we found that miR-18a promotes the expression Cyclin D1 by targeting PTEN in eophageal squamous cell carcinoma TE13 and Eca109 cells. Transfection of miR-18a mimetics increased cyclin D1, while transfection of miR-18a antagomir decreased D1. Moreover, miR-18a-mediated upregulation of cyclin D1 was accompanied with downregulation of PTEN, which is a directmore » target of miR-18a, and increase of the phosphorylation of AKT and S6K1. In addition, pharmacologic inhibition of AKT or mTOR kinases abolished the increase of cyclinD1 by miR-18a, which was accompanied with decreased phosphorylation of Rb−S780 and inhibition of cell proliferation. Our results demonstrated the upregulation of miR-18a promoted cell proliferation by increasing cylin D1 via regulating PTEN-PI3K-AKT-mTOR signaling axis, suggesting that small molecule inhibitors of AKT-mTOR signaling are potential agents for the treatment of ESCC patients with upregulation of miR-17-92 cluster. - Highlights: • miR-18a promotes the proliferation of ESCC cells. • miR-18a increase cyclin D1 expression in ESCC cells. • miR-18a directly targets PTEN in ESCC cells. • Inhibition of AKT-mTOR prevents miR-18a-induced cyclin D1 in ESCC cells. • miR-18a antagomir sensitizes ESCC cells to cisplatin.« less

miR-19a correlates with poor prognosis of clear cell renal cell carcinoma patients via promoting cell proliferation and suppressing PTEN/SMAD4 expression.

PubMed

Ma, Qiang; Peng, Zhiqiang; Wang, Lei; Li, Yanming; Wang, Kaizhen; Zheng, Junfang; Liang, Zhiyong; Liu, Tonghua

2016-12-01

MicroRNAs (miRNAs) were reported to be involved in the development of clear cell renal cell carcinoma (ccRCC). However, the study on miRNAs in ccRCC is far from complete. The present study identified miRNAs which could act as potential novel prognostic markers for ccRCC, and analyzed its possible mechanism. We found that miR-19a correlated with poor prognosis of ccRCC patients via promoting cell proliferation and suppressing PTEN/SMAD4 expression. Both the microarray screening result and TCGA KIRC dataset analysis showed that miR-19a was significantly upregulated in ccRCC tissues, and further analysis of TCGA data revealed that the upregulated level of miR-19a was strongly associated with advanced T stage and poor prognosis of ccRCC patients. Consistent with clinical observations, miR-19a overexpression significantly promoted ccRCC cell proliferation in vitro. To further explore the mechanism by which miR-19a correlated with cell proliferation and poor prognosis of ccRCC, we performed gene set enrichment analysis (GSEA) for target genes of miR-19a in ccRCC patients. Result indicated that the key target genes of miR-19a included SMAD4 and PTEN. In ccRCC tissues, expression levels of SMAD4 and PTEN were negatively correlated with expression level of miR-19a, revealing that miR-19a suppressed the expression of SMAD4 and PTEN in ccRCC patients. miR-19a overexpression significantly suppressed the expression of SMAD4 and PTEN in vitro, further verifying that SMAD4 and PTEN were the target genes of miR-19a in ccRCC cells. Our results elucidated the tumor promoting role of miR-19a and established miR-19a as a potential novel prognostic marker for ccRCC.

High frequency of PTEN mutations in nevi and melanomas from xeroderma pigmentosum patients.

PubMed

Masaki, Taro; Wang, Yun; DiGiovanna, John J; Khan, Sikandar G; Raffeld, Mark; Beltaifa, Senda; Hornyak, Thomas J; Darling, Thomas N; Lee, Chyi-Chia R; Kraemer, Kenneth H

2014-05-01

We examined nevi and melanomas in 10 xeroderma pigmentosum (XP) patients with defective DNA repair. The lesions had a lentiginous appearance with markedly increased numbers of melanocytes. Using laser capture microdissection, we performed DNA sequencing of 18 benign and atypical nevi and 75 melanomas (melanoma in situ and invasive melanomas). The nevi had a similar high frequency of PTEN mutations as melanomas [61% (11/18) versus 53% (39/73)]. Both had a very high proportion of UV-type mutations (occurring at adjacent pyrimidines) [91% (10/11) versus 92% (36/39)]. In contrast to melanomas in the general population, the frequency of BRAF mutations (11%, 7/61), NRAS mutations (21%, 13/62), and KIT mutations (21%, 6/28) in XP melanomas was lower than for PTEN. Phospho-S6 immunostaining indicated activation of the mTOR pathway in the atypical nevi and melanomas. Thus, the clinical and histological appearances and the molecular pathology of these UV-related XP nevi and melanomas were different from nevi and melanomas in the general population. © 2014 Published 2014. This article is a U.S. Government work and is in the public domain in the USA.

LncRNA CASC2 Interacts With miR-181a to Modulate Glioma Growth and Resistance to TMZ Through PTEN Pathway.

PubMed

Liao, Yiwei; Shen, Liangfang; Zhao, Haiting; Liu, Qing; Fu, Jun; Guo, Yong; Peng, Renjun; Cheng, Lei

2017-07-01

Temozolomide (TMZ)-based chemotherapy is a standard strategy for glioma, while chemoresistance remains a major therapeutic challenge. Recent evidence highlights the crucial regulatory roles of long non-coding RNAs (lncRNA) in tumor biology. However, the roles and regulatory mechanisms of lncRNA cancer susceptibility candidate 2 (CASC2), in glioma tumorigenesis and chemoresistance are poorly understood. In this study, CASC2 expression was down-regulated in glioma tissues and cell lines, and was related to a clinicopathologic features and shorter survival time. Exogenous CACS2 alone was sufficient to inhibit glioma cells' proliferation and amplified TMZ-induced repression of cell proliferation, while CACS2 knockdown could reverse this process. CACS2 overexpression could sensitize TMZ-resistant glioma cells to TMZ, while CACS2 knockdown exerted the opposite function. Moreover, CASC2 could inhibit the miR-181a expression by direct targeting in TMZ-resistant glioma cells. CASC2 up-regulated PTEN protein and down-regulated p-AKT protein through regulating miR-181a, and the effect of CASC2 on PTEN and p-AKT could be partially restored by miR-181a. With TMZ-resistant glioma tissues, miR-181a was up-regulated while PTEN was down-regulated. Taken together, these observations suggest CASC2 up-regulates PTEN through direct inhibiting miR-181a and plays an important role in glioma sensitivity to TMZ and may serve as a potential target for cancer diagnosis and treatment. J. Cell. Biochem. 118: 1889-1899, 2017. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

A PTEN-COL17A1 fusion gene and its novel regulatory role in Collagen XVII expression and GBM malignance.

PubMed

Yan, Xiaoyan; Zhang, Chuanbao; Liang, Tingyu; Yang, Fan; Wang, Haoyuan; Wu, Fan; Wang, Wen; Wang, Zheng; Cheng, Wen; Xu, Jiangnan; Jiang, Tao; Chen, Jing; Ding, Yaozhong

2017-10-17

Collagen XVII expression has recently been demonstrated to be correlated with the tumor malignance. While Collagen XVII is known to be widely distributed in neurons of the human brain, its precise role in pathogenesis of glioblastoma multiforme (GBM) is unknown. In this study, we identified and characterized a new PTEN-COL17A1 fusion gene in GMB using transcriptome sequencing. Although fusion gene did not result in measurable fusion protein production, its presence is accompanied with high levels of COL17A1 expression, revealed a novel regulatory mechanism of Collagen XVII expression by PTEN-COL17A1 gene fusion. Knocked down Collagen XVII expression in glioma cell lines resulted in decreased tumor invasiveness, along with significant reduction of MMP9 expression, while increased Collagen XVII expression promotes invasive activities of glioma cells and associated with GBM recurrences. Together, our results uncovered a new PTEN-COL17A1 fusion gene and its novel regulatory role in Collagen XVII expression and GBM malignance, and demonstrated that COL17A1 could serve as a useful prognostic biomarker and therapeutic targets for GBM.

miR-21 inhibitor suppresses cell proliferation and colony formation through regulating the PTEN/AKT pathway and improves paclitaxel sensitivity in cervical cancer cells.

PubMed

Du, Guohui; Cao, Dongmei; Meng, Lingzheng

2017-05-01

The present study aimed to investigate the role and the molecular mechanisms underlying the effects of microRNA-21 (miR-21) on the proliferation, apoptosis and colony formation of cervical cancer cells, and to examine the role of miR-21 in mediating the sensitivity of cervical cancer cells to paclitaxel (PTX). Reverse transcription‑quantitative polymerase chain reaction was employed to determine the level of miR‑21 in various cervical cancer and normal cervical cells. The results revealed that the expression levels of miR-21 in cervical cancer cells were markedly higher when compared with normal cervical cells. Subsequently, a miR‑21 inhibitor or negative control (NC) was transfected into cervical cancer cells. Cell viability, colony formation and apoptosis were then analyzed using an MTT assay, crystal violet and Annexin V-fluorescein isothiocyanate/propidium iodide staining, respectively. The protein expression level of B-cell lymphoma‑2 (Bcl‑2), Bcl‑2‑associated X (Bax), programmed cell death 4 (PDCD4), survivin, c‑myc, phosphatase and tensin homolog (PTEN) and phosphorylated (p)‑AKT were determined by western blot analysis. The sensitivity of cervical cancer cells to PTX (25, 50 and 100 µg/ml) was characterized using an MTT assay. The results demonstrated that the miR-21 inhibitor promoted apoptosis of cervical cancer cells and suppressed their proliferation and colony formation when compared with the NC. In addition, the expression levels of Bcl‑2, survivin, c‑myc and p‑AKT were significantly downregulated in cells transfected with the miR‑21 inhibitor, whilst the expression levels of Bax, PDCD4 and PTEN were significantly upregulated. Furthermore, the miR‑21 inhibitor significantly enhanced the inhibition efficacy of PTX at a range of concentrations in cervical cancer cells. It was concluded that inhibition of miR‑21 suppressed cell proliferation and colony formation through regulating the PTEN/AKT pathway, and improved PTX

Coexistence of the loss of heterozygosity at the PTEN locus and HER2 overexpression enhances the Akt activity thus leading to a negative progesterone receptor expression in breast carcinoma.

PubMed

Tokunaga, Eriko; Oki, Eiji; Kimura, Yasue; Yamanaka, Takeharu; Egashira, Akinori; Nishida, Kojiro; Koga, Tadashi; Morita, Masaru; Kakeji, Yoshihiro; Maehara, Yoshihiko

2007-03-01

Serine/threonine kinase Akt/PKB is known to regulate divergent cellular processes, including apoptosis, proliferation, differentiation, and metabolism. Akt is activated by a variety of stimuli, through such growth factor receptors as HER2, in phosphoinositide-3-OH kinase (PI3K)-dependent manner. A loss of phosphatase and tensin homolog deleted on chromosome 10 (PTEN) function also activates Akt. It has recently been shown that Akt activation is associated with a worse outcome among endocrine treated breast cancer patients and that it also inhibits the progesterone receptor (PR) expression via the PI3K/Akt pathway in breast cancer cells. Therefore, the PI3K/Akt signaling pathway has recently attracted considerable attention as a new target for effective therapeutic strategies. In the present study, we investigated the relationship between Akt activation and either HER2 overexpression or PTEN gene alteration, as well as the PR expression. We analyzed the incidence of LOH at the PTEN locus in 138 breast cancer patients, using our new system for microsatellite analysis, called high-resolution fluorescent microsatellite analysis (HRFMA). We showed Akt activation to significantly correlate with HER2 overexpression or LOH at the PTEN gene locus while inversely correlating with the PR expression. In addition, when LOH at the PTEN gene locus and HER2 overexpression occurred simultaneously, the incidence of Akt activation and reduced PR expression was significant. The association between Akt activation and PR negative expression was observed even in the ER-positive cases. Our results suggest that simultaneous PTEN LOH and HER2 overexpression enhances Akt activation and may thus lead to a negative PR expression.

10 CFR 20.1203 - Determination of external dose from airborne radioactive material.

Code of Federal Regulations, 2014 CFR

2014-01-01

... 10 Energy 1 2014-01-01 2014-01-01 false Determination of external dose from airborne radioactive material. 20.1203 Section 20.1203 Energy NUCLEAR REGULATORY COMMISSION STANDARDS FOR PROTECTION AGAINST RADIATION Occupational Dose Limits § 20.1203 Determination of external dose from airborne radioactive...

10 CFR 20.1203 - Determination of external dose from airborne radioactive material.

Code of Federal Regulations, 2012 CFR

2012-01-01

... 10 Energy 1 2012-01-01 2012-01-01 false Determination of external dose from airborne radioactive material. 20.1203 Section 20.1203 Energy NUCLEAR REGULATORY COMMISSION STANDARDS FOR PROTECTION AGAINST RADIATION Occupational Dose Limits § 20.1203 Determination of external dose from airborne radioactive...

10 CFR 20.1203 - Determination of external dose from airborne radioactive material.

Code of Federal Regulations, 2010 CFR

2010-01-01

... 10 Energy 1 2010-01-01 2010-01-01 false Determination of external dose from airborne radioactive material. 20.1203 Section 20.1203 Energy NUCLEAR REGULATORY COMMISSION STANDARDS FOR PROTECTION AGAINST RADIATION Occupational Dose Limits § 20.1203 Determination of external dose from airborne radioactive...

10 CFR 20.1203 - Determination of external dose from airborne radioactive material.

Code of Federal Regulations, 2011 CFR

2011-01-01

... 10 Energy 1 2011-01-01 2011-01-01 false Determination of external dose from airborne radioactive material. 20.1203 Section 20.1203 Energy NUCLEAR REGULATORY COMMISSION STANDARDS FOR PROTECTION AGAINST RADIATION Occupational Dose Limits § 20.1203 Determination of external dose from airborne radioactive...

10 CFR 20.1203 - Determination of external dose from airborne radioactive material.

Code of Federal Regulations, 2013 CFR

2013-01-01

... 10 Energy 1 2013-01-01 2013-01-01 false Determination of external dose from airborne radioactive material. 20.1203 Section 20.1203 Energy NUCLEAR REGULATORY COMMISSION STANDARDS FOR PROTECTION AGAINST RADIATION Occupational Dose Limits § 20.1203 Determination of external dose from airborne radioactive...

PTP1B Deficiency Enables the Ability of a High-Fat Diet to Drive the Invasive Character of PTEN-Deficient Prostate Cancers.

PubMed

Labbé, David P; Uetani, Noriko; Vinette, Valérie; Lessard, Laurent; Aubry, Isabelle; Migon, Eva; Sirois, Jacinthe; Haigh, Jody J; Bégin, Louis R; Trotman, Lloyd C; Paquet, Marilène; Tremblay, Michel L

2016-06-01

Diet affects the risk and progression of prostate cancer, but the interplay between diet and genetic alterations in this disease is not understood. Here we present genetic evidence in the mouse showing that prostate cancer progression driven by loss of the tumor suppressor Pten is mainly unresponsive to a high-fat diet (HFD), but that coordinate loss of the protein tyrosine phosphatase Ptpn1 (encoding PTP1B) enables a highly invasive disease. Prostate cancer in Pten(-/-)Ptpn1(-/-) mice was characterized by increased cell proliferation and Akt activation, interpreted to reflect a heightened sensitivity to IGF-1 stimulation upon HFD feeding. Prostate-specific overexpression of PTP1B was not sufficient to initiate prostate cancer, arguing that it acted as a diet-dependent modifier of prostate cancer development in Pten(-/-) mice. Our findings offer a preclinical rationale to investigate the anticancer effects of PTP1B inhibitors currently being studied clinically for diabetes treatment as a new modality for management of prostate cancer. Cancer Res; 76(11); 3130-5. ©2016 AACR. ©2016 American Association for Cancer Research.

A practical approach to determine dose metrics for nanomaterials.

PubMed

Delmaar, Christiaan J E; Peijnenburg, Willie J G M; Oomen, Agnes G; Chen, Jingwen; de Jong, Wim H; Sips, Adriënne J A M; Wang, Zhuang; Park, Margriet V D Z

2015-05-01

Traditionally, administered mass is used to describe doses of conventional chemical substances in toxicity studies. For deriving toxic doses of nanomaterials, mass and chemical composition alone may not adequately describe the dose, because particles with the same chemical composition can have completely different toxic mass doses depending on properties such as particle size. Other dose metrics such as particle number, volume, or surface area have been suggested, but consensus is lacking. The discussion regarding the most adequate dose metric for nanomaterials clearly needs a systematic, unbiased approach to determine the most appropriate dose metric for nanomaterials. In the present study, the authors propose such an approach and apply it to results from in vitro and in vivo experiments with silver and silica nanomaterials. The proposed approach is shown to provide a convenient tool to systematically investigate and interpret dose metrics of nanomaterials. Recommendations for study designs aimed at investigating dose metrics are provided. © 2015 SETAC.

Ovarian and endometrial endometrioid carcinomas have distinct CTNNB1 and PTEN mutation profiles.

PubMed

McConechy, Melissa K; Ding, Jiarui; Senz, Janine; Yang, Winnie; Melnyk, Nataliya; Tone, Alicia A; Prentice, Leah M; Wiegand, Kimberly C; McAlpine, Jessica N; Shah, Sohrab P; Lee, Cheng-Han; Goodfellow, Paul J; Gilks, C Blake; Huntsman, David G

2014-01-01

Ovarian endometrioid carcinomas and endometrial endometrioid carcinomas share many histological and molecular alterations. These similarities are likely due to a common endometrial epithelial precursor cell of origin, with most ovarian endometrioid carcinomas arising from endometriosis. To directly compare the mutation profiles of two morphologically similar tumor types, endometrial endometrioid carcinomas (n=307) and ovarian endometrioid carcinomas (n=33), we performed select exon capture sequencing on a panel of genes: ARID1A, PTEN, PIK3CA, KRAS, CTNNB1, PPP2R1A, TP53. We found that PTEN mutations are more frequent in low-grade endometrial endometrioid carcinomas (67%) compared with low-grade ovarian endometrioid carcinomas (17%) (P<0.0001). By contrast, CTNNB1 mutations are significantly different in low-grade ovarian endometrioid carcinomas (53%) compared with low-grade endometrial endometrioid carcinomas (28%) (P<0.0057). This difference in CTNNB1 mutation frequency may be reflective of the distinct microenvironments; the epithelial cells lining an endometriotic cyst within the ovary are exposed to a highly oxidative environment that promotes tumorigenesis. Understanding the distinct mutation patterns found in the PI3K and Wnt pathways of ovarian and endometrial endometrioid carcinomas may provide future opportunities for stratifying patients for targeted therapeutics.

MicroRNA-29a contributes to drug-resistance of breast cancer cells to adriamycin through PTEN/AKT/GSK3β signaling pathway.

PubMed

Shen, Hongyu; Li, Liangpeng; Yang, Sujin; Wang, Dandan; Zhong, Shanliang; Zhao, Jianhua; Tang, Jinhai

2016-11-15

Acquisition of resistance to adriamycin (ADR) during the treatment of breast cancer is still a major clinical obstacle. MicroRNAs (miRNAs) are a class of short noncoding RNAs which associate with cancer chemoresistance through regulating gene expression by targeting mRNAs. Our previous microarray found that miR-29a may strongly confer the ADR resistance of breast cancer cells. Here, we aim to explore the possible mechanism by which miR-29a affects sensitivity to ADR. ADR-resistant MCF-7 breast cancer cell subline (MCF-7/ADR) was successfully established in vitro through a stepwise increase of ADR concentrations in the culture based on parental MCF-7 cell lines (MCF-7/S). We used TargetScan (a wide use of target prediction algorithms) in conjunction with pathway enrichment analyses to predict the mRNAs that were most likely to involve in miR-29a-mediated drug resistance in cancers. We confirmed the effects of miR-29a-mediated ADR resistance through MTT and apoptosis assays, and further investigated the activities of two target genes, PTEN and GSK3β, by RT-qPCR analyses and western blot assays. The expression level of miR-29a in MCF-7/ADR cells was remarkablely higher than in MCF-7/S cells. Further MTT and apoptosis assays revealed that transfection of miR-29a inhibitors into MCF-7/ADR cells resulted in prominent reduction of the drug resistance, in contrast, transfection of miR-29a mimics into MCF-7/S cells obviously increased their drug resistance. Through pathway enrichment analyses for miR-29a, we found that PTEN/AKT/GSK3β signaling pathway may be of importance. RT-qPCR and Western blot results showed that downregulation of miR-29a expression in MCF-7/ADR cells increased PTEN expression levels, resulting in decreased phospho-Akt (p-Akt) and phospho-GSK3β (p-GSK3β) expression. Conversely, upregulation of miR-29a expression in MCF-7/S cells is associated with decreasing PTEN expression and increasing p-Akt and p-GSK3β expression. PTEN and GSK3β are targeted

Anti-cancer effect of ursolic acid activates apoptosis through ROCK/PTEN mediated mitochondrial translocation of cofilin-1 in prostate cancer

PubMed Central

Gai, Wen-Tao; Yu, Da-Peng; Wang, Xin-Sheng; Wang, Pei-Tao

2016-01-01

Ursolic acid is a type of pentacyclic triterpene compound with multiple pharmacological activities including cancer resistance, protection from liver injury, antisepsis, anti-inflammation and antiviral activity. The present study aimed to investigate the anticancer effect of ursolic acid. Ursolic acid activates cell apoptosis and its pro-apoptotic mechanism remains to be fully elucidated. Cell Counting kit-8 assays, flow cytometric analysis and analysis of caspase-3 and caspase-9 activity were used to estimate the anticancer effect of ursolic acid on DU145 prostate cancer cells. The protein expression of cytochrome c, rho-associated protein kinase (ROCK), phosphatase and tensin homolog (PTEN) and cofilin-1 were examined using western blot analysis. In the present study, ursolic acid significantly suppressed cell growth and induced apoptosis, as well as increasing caspase-3 and caspase-9 activities of DU145 cells. Furthermore, cytoplasmic and mitochondrial cytochrome c protein expression was significantly activated and suppressed, respectively, by ursolic acid. Ursolic acid significantly suppressed the ROCK/PTEN signaling pathway and inhibited cofilin-1 protein expression in DU145 cells. The results of the present study indicate that the anticancer effect of ursolic acid activates cell apoptosis through ROCK/PTEN mediated mitochondrial translocation of cofilin-1 in prostate cancer. PMID:27698874

Deletion of PTEN Produces Deficits in Conditioned Fear and Increases Fragile X Mental Retardation Protein

ERIC Educational Resources Information Center

Lugo, Joaquin N.; Smith, Gregory D.; Morrison, Jessica B.; White, Jessika

2013-01-01

The phosphatase and tensin homolog detected on chromosome 10 (PTEN) gene product modulates activation of the phosphatidylinositol 3-kinase (PI3K)/AKT pathway. The PI3K pathway has been found to be involved in the regulation of the fragile X mental retardation protein, which is important for long-term depression and in the formation of new…

Short-Term PTEN Inhibition Improves In Vitro Activation of Primordial Follicles, Preserves Follicular Viability, and Restores AMH Levels in Cryopreserved Ovarian Tissue From Cancer Patients

PubMed Central

Novella-Maestre, Edurne; Herraiz, Sonia; Rodríguez-Iglesias, Beatriz; Díaz-García, César; Pellicer, Antonio

2015-01-01

Introduction In vitro activation and growth of primordial dormant follicles to produce fertilizable oocytes would provide a useful instrument for fertility preservation. The employment of Phosphatase and TENsin homolog (PTEN) inhibitors, in combination with Protein kinase B (Akt) stimulating molecules, has been previously employed to increase follicular activation through the stimulation of the PTEN-Akt pathway. Methods We aim to establish improved in vitro activation also for cancer patients whose ovarian tissue has already been cryopreserved. Fresh and previously cryopreserved human ovarian cortex were exposed to short-term, low-concentration and ovary-specific treatment with only a PTEN inhibitor. Results Our in vitro activation protocol enhances the activation mechanisms of primordial follicles in both fresh and cryopreserved samples, and enlarges growing populations without inducing apoptosis in either follicles or the surrounding stroma. Treatment augments estradiol secretion and restores the expression levels of the previously diminished Anti-Müllerian hormone by means of cryopreservation procedures. Genomic modulation of the relative expression of PTEN pathway genes was found in treated samples. Conclusion The in vitro activation protocol offers new alternatives for patients with cryopreserved tissue as it increases the pool of viable activated follicles available for in vitro growth procedures. The combination of ovarian tissue cryopreservation and in vitro activation of primordial follicles, the main ovarian reserve component, will be a major advancement in fertility preservation. PMID:26024525

Short-Term PTEN Inhibition Improves In Vitro Activation of Primordial Follicles, Preserves Follicular Viability, and Restores AMH Levels in Cryopreserved Ovarian Tissue From Cancer Patients.

PubMed

Novella-Maestre, Edurne; Herraiz, Sonia; Rodríguez-Iglesias, Beatriz; Díaz-García, César; Pellicer, Antonio

2015-01-01

In vitro activation and growth of primordial dormant follicles to produce fertilizable oocytes would provide a useful instrument for fertility preservation. The employment of Phosphatase and TENsin homolog (PTEN) inhibitors, in combination with Protein kinase B (Akt) stimulating molecules, has been previously employed to increase follicular activation through the stimulation of the PTEN-Akt pathway. We aim to establish improved in vitro activation also for cancer patients whose ovarian tissue has already been cryopreserved. Fresh and previously cryopreserved human ovarian cortex were exposed to short-term, low-concentration and ovary-specific treatment with only a PTEN inhibitor. Our in vitro activation protocol enhances the activation mechanisms of primordial follicles in both fresh and cryopreserved samples, and enlarges growing populations without inducing apoptosis in either follicles or the surrounding stroma. Treatment augments estradiol secretion and restores the expression levels of the previously diminished Anti-Müllerian hormone by means of cryopreservation procedures. Genomic modulation of the relative expression of PTEN pathway genes was found in treated samples. The in vitro activation protocol offers new alternatives for patients with cryopreserved tissue as it increases the pool of viable activated follicles available for in vitro growth procedures. The combination of ovarian tissue cryopreservation and in vitro activation of primordial follicles, the main ovarian reserve component, will be a major advancement in fertility preservation.

Low concentration of formononetin promotes proliferation of estrogen receptor-positive cells through an ERα-miR-375-PTEN-ERK1/2-bcl-2 pathway.

PubMed

Guo, Yan-Hong; Tang, Feng-Yan; Wang, Yong; Huang, Wen-Jun; Tian, Jing; Lu, Hui-Ling; Xin, Min; Chen, Jian

2017-11-21

A low dose of formononetin accelerates the proliferation of nasopharyngeal carcinoma cells in vitro ; however, the underlying mechanism remains unknown. Here, we investigated the molecular mechanism of formononetin in CNE2 cell proliferation. CNE2 cells were treated with 0 to 1 μM formononetin. To inhibit mitogen activated protein kinase / extracellular regulate kinase (MAPK/ERK) kinase (MEK) and microRNA (miR)-375, cells were pretreated with either PD98059 or a miR-375 inhibitor, respectively, followed by co-treatment with formononetin (0.3 μM) plus an inhibitor. Female rats were ovariectomized (OVX), and some OVX rats received formononetin or estrogen (E 2 ) injections. Sham operated animals were used as controls. Compared to control, 0.3 μM formononetin accelerated proliferation and decreased late apoptosis of CNE2 cells. However, formononetin-induced pro-growth and anti-apoptosis activity was abolished by PD98059 and the miR-375 inhibitor. In addition, 0.1 and 0.3 μM formononetin significantly increased estrogen receptor-α (ERα) and bcl-2, but decreased protein-phosphatase and tensin homologue (PTEN) protein expression, all of which was reversed by the miR-375 inhibitor. Additionally, formononetin treatment resulted in a transient upregulation of phosphorylated (p)-ERK1/2. In vivo studies indicated that formononetin significantly increased endometrium thickness and down-regulated ERα expression in OVX rats. Taken together, our study demonstrates that a low concentration of formononetin can promote growth of CNE2 cells and uterine tissues, possibly through regulating the ERα-miR-375-PTEN-ERK1/2-bcl-2 signaling pathway.

Low concentration of formononetin promotes proliferation of estrogen receptor-positive cells through an ERα-miR-375-PTEN-ERK1/2-bcl-2 pathway

PubMed Central

Guo, Yan-Hong; Tang, Feng-Yan; Wang, Yong; Huang, Wen-Jun; Tian, Jing; Lu, Hui-Ling; Xin, Min; Chen, Jian

2017-01-01

A low dose of formononetin accelerates the proliferation of nasopharyngeal carcinoma cells in vitro; however, the underlying mechanism remains unknown. Here, we investigated the molecular mechanism of formononetin in CNE2 cell proliferation. CNE2 cells were treated with 0 to 1 μM formononetin. To inhibit mitogen activated protein kinase / extracellular regulate kinase (MAPK/ERK) kinase (MEK) and microRNA (miR)-375, cells were pretreated with either PD98059 or a miR-375 inhibitor, respectively, followed by co-treatment with formononetin (0.3 μM) plus an inhibitor. Female rats were ovariectomized (OVX), and some OVX rats received formononetin or estrogen (E2) injections. Sham operated animals were used as controls. Compared to control, 0.3 μM formononetin accelerated proliferation and decreased late apoptosis of CNE2 cells. However, formononetin-induced pro-growth and anti-apoptosis activity was abolished by PD98059 and the miR-375 inhibitor. In addition, 0.1 and 0.3 μM formononetin significantly increased estrogen receptor-α (ERα) and bcl-2, but decreased protein-phosphatase and tensin homologue (PTEN) protein expression, all of which was reversed by the miR-375 inhibitor. Additionally, formononetin treatment resulted in a transient upregulation of phosphorylated (p)-ERK1/2. In vivo studies indicated that formononetin significantly increased endometrium thickness and down-regulated ERα expression in OVX rats. Taken together, our study demonstrates that a low concentration of formononetin can promote growth of CNE2 cells and uterine tissues, possibly through regulating the ERα-miR-375-PTEN-ERK1/2-bcl-2 signaling pathway. PMID:29245959

Immunohistochemical analysis of PTEN, HER2/neu, and ki67 expression in patients with gastric cancer and their association with survival.

PubMed

Badary, Dalia M; Abdel-Wanis, Mostafa E; Hafez, Mohamed Z; Aboulhagag, Noha A

2017-06-01

Considering the poor prognosis of patients with gastric cancer, molecular diagnostic and prognostic markers for this cancer should be established. The aims of our study were to assess the correlations between PTEN, HER2/neu, and Ki67 expressions and clinicopathological factors of gastric cancer patients in upper Egypt, as well as their influence on OS and DFS. In this descriptive-analytic study, 42 patients with gastric carcinoma treated by postioerative chemoradiation between 2004 and 2014. Pathological review was done. Immunohistochemical staining and evaluation were performed. All the studied markers were significantly correlated with increased TNM stage. Her2/neu overexpression and positive Ki67 expression were significantly associated with histological grade. High percentage of positive Her2/neu and Ki67expression was found in gastric carcinoma tissue samples which lack PTEN expression. The one-year OS rate for the entire group (n=42) was 77.4%, whereas the DFS rate was 45%. Pathological T stage PTEN status significantly affected both OS (p=0.029 and 0.027 respectively) and DFS (p=0.006 and 0.012 respectively) rates. Multivariate Cox analyses showed that only pathological T stage was an independent prognostic factor affecting OS (P=0. 007, HR: 2.02; 95% CI: 1.2-3.38)and DFS(P<0.0001, HR: 2.69; 95% CI: 1.54-4.69). All the studied molecular markers, was significantly correlated with pathological T stage that significantly affected both OS and DFS rates. These findings indicate that these markers have an important role in gastric cancer growth and dissemination so these markers can be used as a prognostic biomarker. In addition, therapies targeting Her2 and PTEN may help develop novel therapeutics for gastric cancer. Copyright © 2017 Elsevier B.V. All rights reserved.

The metabolic perturbators metformin, phenformin and AICAR interfere with the growth and survival of murine PTEN-deficient T cell lymphomas and human T-ALL/T-LL cancer cells.

PubMed

Rosilio, Célia; Lounnas, Nadia; Nebout, Marielle; Imbert, Véronique; Hagenbeek, Thijs; Spits, Hergen; Asnafi, Vahid; Pontier-Bres, Rodolphe; Reverso, Julie; Michiels, Jean-François; Sahra, Issam Ben; Bost, Fréderic; Peyron, Jean-François

2013-08-09

We show here that the antidiabetic agents metformin and phenformin and the AMPK activator AICAR exert strong anti-tumoural effects on tPTEN-/- lymphoma cells and on human T-ALL cell lines and primary samples. The compounds act by inhibiting tumour metabolism and proliferation and by inducing apoptosis in parallel with an activation of AMPK and an inhibition of constitutive mTOR. In tPTEN-/- cells, the drugs potentiated the anti-leukaemic effects of dexamethasone, and metformin and phenformin synergised with 2-deoxyglucose (2DG) to impair tumour cell survival. In vivo, metformin and AICAR strongly decreased the growth of luciferase-expressing tPTEN-/- cells xenografted in Nude mice, demonstrating that metabolism targeting could be a potent adjuvant strategy for lymphoma/leukaemia treatment. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Neuromuscular dose-response studies: determining sample size.

PubMed

Kopman, A F; Lien, C A; Naguib, M

2011-02-01

Investigators planning dose-response studies of neuromuscular blockers have rarely used a priori power analysis to determine the minimal sample size their protocols require. Institutional Review Boards and peer-reviewed journals now generally ask for this information. This study outlines a proposed method for meeting these requirements. The slopes of the dose-response relationships of eight neuromuscular blocking agents were determined using regression analysis. These values were substituted for γ in the Hill equation. When this is done, the coefficient of variation (COV) around the mean value of the ED₅₀ for each drug is easily calculated. Using these values, we performed an a priori one-sample two-tailed t-test of the means to determine the required sample size when the allowable error in the ED₅₀ was varied from ±10-20%. The COV averaged 22% (range 15-27%). We used a COV value of 25% in determining the sample size. If the allowable error in finding the mean ED₅₀ is ±15%, a sample size of 24 is needed to achieve a power of 80%. Increasing 'accuracy' beyond this point requires increasing greater sample sizes (e.g. an 'n' of 37 for a ±12% error). On the basis of the results of this retrospective analysis, a total sample size of not less than 24 subjects should be adequate for determining a neuromuscular blocking drug's clinical potency with a reasonable degree of assurance.

Molecular Mechanism of Nkx3.1 Deregulation and Its Function in Murine Pten Prostate Cancer Model

DTIC Science & Technology

2005-09-01

we failed to detect any significant alterations in WT grafts. One possible explanation is that Pten null cells have became " addicted " to high levels...Freeman, D. J., Li, A. G., Wei, G., Li, H. H., Kertesz, N., Lesche, R., Whale , A. D., Martinez-Diaz, H., Rozengurt, N., Cardiff, R. D., et al. (2003

Ir-192 HDR transit dose and radial dose function determination using alanine/EPR dosimetry

NASA Astrophysics Data System (ADS)

Guzmán Calcina, Carmen S.; de Almeida, Adelaide; Oliveira Rocha, José R.; Abrego, Felipe Chen; Baffa, Oswaldo

2005-03-01

Source positioning close to the tumour in high dose rate (HDR) brachytherapy is not instantaneous. An increment of dose will be delivered during the movement of the source in the trajectory to its static position. This increment is the transit dose, often not taken into account in brachytherapeutic treatment planning. The transit dose depends on the prescribed dose, number of treatment fractions, velocity and activity of the source. Combining all these factors, the transit dose can be 5% higher than the prescribed absorbed dose value (Sang-Hyun and Muller-Runkel, 1994 Phys. Med. Biol. 39 1181 8, Nath et al 1995 Med. Phys. 22 209 34). However, it cannot exceed this percentage (Nath et al 1995). In this work, we use the alanine-EPR (electron paramagnetic resonance) dosimetric system using analysis of the first derivative of the signal. The transit dose was evaluated for an HDR system and is consistent with that already presented for TLD dosimeters (Bastin et al 1993 Int. J. Radiat. Oncol. Biol. Phys. 26 695 702). Also using the same dosimetric system, the radial dose function, used to evaluate the geometric dose degradation around the source, was determined and its behaviour agrees better with those obtained by Monte Carlo simulations (Nath et al 1995, Williamson and Nath 1991 Med. Phys. 18 434 48, Ballester et al 1997 Med. Phys. 24 1221 8, Ballester et al 2001 Phys. Med. Biol. 46 N79 90) than with TLD measurements (Nath et al 1990 Med. Phys. 17 1032 40).

Ir-192 HDR transit dose and radial dose function determination using alanine/EPR dosimetry.

PubMed

Calcina, Carmen S Guzmán; de Almeida, Adelaide; Rocha, José R Oliveira; Abrego, Felipe Chen; Baffa, Oswaldo

2005-03-21

Source positioning close to the tumour in high dose rate (HDR) brachytherapy is not instantaneous. An increment of dose will be delivered during the movement of the source in the trajectory to its static position. This increment is the transit dose, often not taken into account in brachytherapeutic treatment planning. The transit dose depends on the prescribed dose, number of treatment fractions, velocity and activity of the source. Combining all these factors, the transit dose can be 5% higher than the prescribed absorbed dose value (Sang-Hyun and Muller-Runkel, 1994 Phys. Med. Biol. 39 1181-8, Nath et al 1995 Med. Phys. 22 209-34). However, it cannot exceed this percentage (Nath et al 1995). In this work, we use the alanine-EPR (electron paramagnetic resonance) dosimetric system using analysis of the first derivative of the signal. The transit dose was evaluated for an HDR system and is consistent with that already presented for TLD dosimeters (Bastin et al 1993 Int. J. Radiat. Oncol. Biol. Phys. 26 695-702). Also using the same dosimetric system, the radial dose function, used to evaluate the geometric dose degradation around the source, was determined and its behaviour agrees better with those obtained by Monte Carlo simulations (Nath et al 1995, Williamson and Nath 1991 Med. Phys. 18 434-48, Ballester et al 1997 Med. Phys. 24 1221-8, Ballester et al 2001 Phys. Med. Biol. 46 N79-90) than with TLD measurements (Nath et al 1990 Med. Phys. 17 1032-40).

Metastatic group 3 medulloblastoma is driven by PRUNE1 targeting NME1-TGF-β-OTX2-SNAIL via PTEN inhibition.

PubMed

Ferrucci, Veronica; de Antonellis, Pasqualino; Pennino, Francesco Paolo; Asadzadeh, Fatemeh; Virgilio, Antonella; Montanaro, Donatella; Galeone, Aldo; Boffa, Iolanda; Pisano, Ida; Scognamiglio, Iolanda; Navas, Luigi; Diana, Donatella; Pedone, Emilia; Gargiulo, Sara; Gramanzini, Matteo; Brunetti, Arturo; Danielson, Laura; Carotenuto, Marianeve; Liguori, Lucia; Verrico, Antonio; Quaglietta, Lucia; Errico, Maria Elena; Del Monaco, Valentina; D'Argenio, Valeria; Tirone, Felice; Mastronuzzi, Angela; Donofrio, Vittoria; Giangaspero, Felice; Picard, Daniel; Remke, Marc; Garzia, Livia; Daniels, Craig; Delattre, Olivier; Swartling, Fredrik J; Weiss, William A; Salvatore, Francesco; Fattorusso, Roberto; Chesler, Louis; Taylor, Michael D; Cinalli, Giuseppe; Zollo, Massimo

2018-05-01

Genetic modifications during development of paediatric groups 3 and 4 medulloblastoma are responsible for their highly metastatic properties and poor patient survival rates. PRUNE1 is highly expressed in metastatic medulloblastoma group 3, which is characterized by TGF-β signalling activation, c-MYC amplification, and OTX2 expression. We describe the process of activation of the PRUNE1 signalling pathway that includes its binding to NME1, TGF-β activation, OTX2 upregulation, SNAIL (SNAI1) upregulation, and PTEN inhibition. The newly identified small molecule pyrimido-pyrimidine derivative AA7.1 enhances PRUNE1 degradation, inhibits this activation network, and augments PTEN expression. Both AA7.1 and a competitive permeable peptide that impairs PRUNE1/NME1 complex formation, impair tumour growth and metastatic dissemination in orthotopic xenograft models with a metastatic medulloblastoma group 3 cell line (D425-Med cells). Using whole exome sequencing technology in metastatic medulloblastoma primary tumour cells, we also define 23 common 'non-synonymous homozygous' deleterious gene variants as part of the protein molecular network of relevance for metastatic processes. This PRUNE1/TGF-β/OTX2/PTEN axis, together with the medulloblastoma-driver mutations, is of relevance for future rational and targeted therapies for metastatic medulloblastoma group 3.10.1093/brain/awy039_video1awy039media15742053534001.

MicroRNA-1908 functions as a glioblastoma oncogene by suppressing PTEN tumor suppressor pathway.

PubMed

Xia, Xuewei; Li, Yong; Wang, Wenbo; Tang, Fang; Tan, Jie; Sun, Liyuan; Li, Qinghua; Sun, Li; Tang, Bo; He, Songqing

2015-08-12

We aimed to investigate whether miRNA-1908 is an oncogene in human glioblastoma and find the possible mechanism of miR-1908. We investigated the growth potentials of miRNA-1908-overexpressing SW-1783 cells in vitro and in vivo. In order to identify the target molecule of miRNA-1908, a luciferase reporter assay was performed, and the corresponding downstream signaling pathway was examined using immunohistochemistry of human glioblastoma tissues. We also investigated the miRNA-1908 expression in 34 patients according to the postoperative risk of recurrence. The overexpression of miRNA-1908 significantly promoted anchorage-independent growth in vitro and significantly increased the tumor forming potential in vivo. MiRNA-1908 significantly suppressed the luciferase activity of mRNA combined with the PTEN 3'-UTR. Furthermore, the expression levels of miRNA-1908 were significantly increased in the patients with a high risk of recurrence compared to that observed in the low-risk patients, and this higher expression correlated with a poor survival. miRNA-1908 functions as an oncogene in glioblastoma by repressing the PTEN pathway. MiR-1908 is a potential new molecular marker for predicting the risk of recurrence and prognosis of glioblastoma.

Committed effective dose determination in southern Brazilian cereal flours.

PubMed

Scheibel, V; Appoloni, C R

2013-01-01

The health impact of radionuclide ingestion from foodstuffs was evaluated by the committed effective doses determined in eight commercial samples of South-Brazilian cereal flours (soy, wheat, cornmeal, cassava, rye, oat, barley and rice flours). The radioactivity traces of (228)Th, (228)Ra, (226)Ra, (40)K, (7)Be and (137)Cs were measured by gamma-ray spectrometry employing an HPGe detector of 66 % relative efficiency. The efficiency curve has taken into account the differences in densities and chemical composition between the matrix and the certified sample. The highest concentration levels of (228)Th and (40)K were 3.5±0.4 and 1469±17 Bq kg(-1) for soy flour, respectively, within the 95 % confidence level. The lower limit of detection for (137)Cs ranged from 0.04 to 0.4 Bq kg(-1). The highest committed effective dose was 0.36 μSv.y(-1) for (228)Ra in cassava flour (adults). All committed effective doses determined at the present work were lower than the International Atomic Energy Agency dose limit of 1 mSv.y(-1), to the public exposure.

Significance of phosphatase and tensin homologue (PTEN), O(6)-methylguanine-DNA methyltransferase (MGMT), and DNA-dependent protein kinase catalytic subunit (DNA-PKcs) protein expression in gynaecomastia.

PubMed

Zhu, L; Liu, Z; Yang, J; Cai, J

2009-01-01

This study was designed to investigate the pathogenesis of gynaecomastia by measuring phosphatase and tensin homologue (PTEN), O(6)-methylguanine-DNA methyltransferase (MGMT) and DNA-dependent protein kinase catalytic subunit (DNA-PKcs) protein in breast tissue specimens from 68 patients with gynaecomastia and 24 normal male controls using immunohistochemical staining. The gynaecomastia cases were divided into three different histological types: florid, intermediate and fibrous. The PTEN, MGMT and DNA-PKcs proteins were detected in both gynaecomastia and normal breast tissue, but the levels of immunohistochemical staining of each protein were significantly lower in gynaecomastia breast tissue than in normal breast tissue. There were also significant differences in the levels of immunohistochemical staining for the three proteins according to gynaecomastia histological type. These results suggest that abnormally low levels of PTEN, MGMT and DNA-PKcs protein in gynaecomastia breast tissue may play a role in the development of gynaecomastia. Further research is required to elucidate fully their individual roles in the pathophysiology of gynaecomastia.

Phenotype selection reveals coevolution of muscle glycogen and protein and PTEN as a gate keeper for the accretion of muscle mass in adult female mice.

PubMed

Sawitzky, Mandy; Zeissler, Anja; Langhammer, Martina; Bielohuby, Maximilian; Stock, Peggy; Hammon, Harald M; Görs, Solvig; Metges, Cornelia C; Stoehr, Barbara J M; Bidlingmaier, Martin; Fromm-Dornieden, Carolin; Baumgartner, Bernhard G; Christ, Bruno; Brenig, Bertram; Binder, Gerhard; Metzger, Friedrich; Renne, Ulla; Hoeflich, Andreas

2012-01-01

We have investigated molecular mechanisms for muscle mass accretion in a non-inbred mouse model (DU6P mice) characterized by extreme muscle mass. This extreme muscle mass was developed during 138 generations of phenotype selection for high protein content. Due to the repeated trait selection a complex setting of different mechanisms was expected to be enriched during the selection experiment. In muscle from 29-week female DU6P mice we have identified robust increases of protein kinase B activation (AKT, Ser-473, up to 2-fold) if compared to 11- and 54-week DU6P mice or controls. While a number of accepted effectors of AKT activation, including IGF-I, IGF-II, insulin/IGF-receptor, myostatin or integrin-linked kinase (ILK), were not correlated with this increase, phosphatase and tensin homologue deleted on chromosome 10 (PTEN) was down-regulated in 29-week female DU6P mice. In addition, higher levels of PTEN phosphorylation were found identifying a second mechanism of PTEN inhibition. Inhibition of PTEN and activation of AKT correlated with specific activation of p70S6 kinase and ribosomal protein S6, reduced phosphorylation of eukaryotic initiation factor 2α (eIF2α) and higher rates of protein synthesis in 29-week female DU6P mice. On the other hand, AKT activation also translated into specific inactivation of glycogen synthase kinase 3ß (GSK3ß) and an increase of muscular glycogen. In muscles from 29-week female DU6P mice a significant increase of protein/DNA was identified, which was not due to a reduction of protein breakdown or to specific increases of translation initiation. Instead our data support the conclusion that a higher rate of protein translation is contributing to the higher muscle mass in mid-aged female DU6P mice. Our results further reveal coevolution of high protein and high glycogen content during the selection experiment and identify PTEN as gate keeper for muscle mass in mid-aged female DU6P mice.

Phenotype Selection Reveals Coevolution of Muscle Glycogen and Protein and PTEN as a Gate Keeper for the Accretion of Muscle Mass in Adult Female Mice

PubMed Central

Sawitzky, Mandy; Zeissler, Anja; Langhammer, Martina; Bielohuby, Maximilian; Stock, Peggy; Hammon, Harald M.; Görs, Solvig; Metges, Cornelia C.; Stoehr, Barbara J. M.; Bidlingmaier, Martin; Fromm-Dornieden, Carolin; Baumgartner, Bernhard G.; Christ, Bruno; Brenig, Bertram; Binder, Gerhard; Metzger, Friedrich; Renne, Ulla; Hoeflich, Andreas

2012-01-01

We have investigated molecular mechanisms for muscle mass accretion in a non-inbred mouse model (DU6P mice) characterized by extreme muscle mass. This extreme muscle mass was developed during 138 generations of phenotype selection for high protein content. Due to the repeated trait selection a complex setting of different mechanisms was expected to be enriched during the selection experiment. In muscle from 29-week female DU6P mice we have identified robust increases of protein kinase B activation (AKT, Ser-473, up to 2-fold) if compared to 11- and 54-week DU6P mice or controls. While a number of accepted effectors of AKT activation, including IGF-I, IGF-II, insulin/IGF-receptor, myostatin or integrin-linked kinase (ILK), were not correlated with this increase, phosphatase and tensin homologue deleted on chromosome 10 (PTEN) was down-regulated in 29-week female DU6P mice. In addition, higher levels of PTEN phosphorylation were found identifying a second mechanism of PTEN inhibition. Inhibition of PTEN and activation of AKT correlated with specific activation of p70S6 kinase and ribosomal protein S6, reduced phosphorylation of eukaryotic initiation factor 2α (eIF2α) and higher rates of protein synthesis in 29-week female DU6P mice. On the other hand, AKT activation also translated into specific inactivation of glycogen synthase kinase 3ß (GSK3ß) and an increase of muscular glycogen. In muscles from 29-week female DU6P mice a significant increase of protein/DNA was identified, which was not due to a reduction of protein breakdown or to specific increases of translation initiation. Instead our data support the conclusion that a higher rate of protein translation is contributing to the higher muscle mass in mid-aged female DU6P mice. Our results further reveal coevolution of high protein and high glycogen content during the selection experiment and identify PTEN as gate keeper for muscle mass in mid-aged female DU6P mice. PMID:22768110

Measured dose to ovaries and testes from Hodgkin's fields and determination of genetically significant dose

DOE Office of Scientific and Technical Information (OSTI.GOV)

Niroomand-Rad, A.; Cumberlin, R.

The purpose of this study was to determine the genetically significant dose from therapeutic radiation exposure with Hodgkin's fields by estimating the doses to ovaries and testes. Phantom measurements were performed to verify estimated doses to ovaries and testes from Hodgkin's fields. Thermoluminescent LiF dosimeters (TLD-100) of 1 x 3 x 3 mm[sup 3] dimensions were embedded in phantoms and exposed to standard mantle and paraaortic fields using Co-60, 4 MV, 6 MV, and 10 MV photon beams. The results show that measured doses to ovaries and testes are about two to five times higher than the corresponding graphically estimatedmore » doses for Co-60 and 4 MVX photon beams as depicted in ICRP publication 44. In addition, the measured doses to ovaries and testes are about 30% to 65% lower for 10 MV photon beams than for their corresponding Co-60 photon beams. The genetically significant dose from Hodgkin's treatment (less than 0.01 mSv) adds about 4% to the genetically significant dose contribution to medical procedures and adds less than 1% to the genetically significant dose from all sources. Therefore, the consequence to society is considered to be very small. The consequences for the individual patient are, likewise, small. 28 refs., 3 figs., 5 tabs.« less

SOX4 is essential for prostate tumorigenesis initiated by PTEN ablation | Office of Cancer Genomics

Cancer.gov

Understanding remains incomplete of the mechanisms underlying initiation and progression of prostate cancer, the most commonly diagnosed cancer in American men. The transcription factor SOX4 is overexpressed in many human cancers, including prostate cancer, suggesting it may participate in prostate tumorigenesis. In this study, we investigated this possibility by genetically deleting Sox4 in a mouse model of prostate cancer initiated by loss of the tumor suppressor Pten.

Association of high microvessel αvβ3 and low PTEN with poor outcome in stage 3 neuroblastoma: rationale for using first in class dual PI3K/BRD4 inhibitor, SF1126

PubMed Central

Singh, Alok R.; Joshi, Shweta; Vega, Francisco M.; Guo, Pinzheng; Xu, Jingying; Groshen, Susan; Ye, Wei; Millard, Melissa; Campan, Mihaela; Morales, Guillermo; Garlich, Joseph R.; Laird, Peter W.; Seeger, Robert C.; Shimada, Hiroyuki

2017-01-01

Neuroblastoma (NB) is the most common extracranial solid tumor in children. Our previous studies showed that the angiogenic integrin αvβ3 was increased in high-risk metastatic (stage 4) NB compared with localized neuroblastomas. Herein, we show that integrin αvβ3 was expressed on 68% of microvessels in MYCN-amplified stage 3 neuroblastomas, but only on 34% (means) in MYCN-non-amplified tumors (p < 0.001; n = 54). PTEN, a tumor suppressor involved in αvβ3 signaling, was expressed in neuroblastomas either diffusely, focally or not at all (immunohistochemistry). Integrin αvβ3 was expressed on 60% of tumor microvessels when PTEN was negative or focal, as compared to 32% of microvessels in tumors with diffuse PTEN expression (p < 0.001). In a MYCN transgenic mouse model, loss of one allele of PTEN promoted tumor growth, illustrating the potential role of PTEN in neuroblastoma pathogenesis. Interestingly, we report the novel dual PI-3K/BRD4 activity of SF1126 (originally developed as an RGD-conjugated pan PI3K inhibitor). SF1126 inhibits BRD4 bromodomain binding to acetylated lysine residues with histone H3 as well as PI3K activity in the MYCN amplified neuroblastoma cell line IMR-32. Moreover, SF1126 suppressed MYCN expression and MYCN associated transcriptional activity in IMR-32 and CHLA136, resulting in overall decrease in neuroblastoma cell viability. Finally, treatment of neuroblastoma tumors with SF1126 inhibited neuroblastoma growth in vivo. These data suggest integrin αvβ3, MYCN/BRD4 and PTEN/PI3K/AKT signaling as biomarkers and hence therapeutic targets in neuroblastoma and support testing of the RGD integrin αvβ3-targeted PI-3K/BRD4 inhibitor, SF1126 as a therapeutic strategy in this specific subgroup of high risk neuroblastoma. PMID:28881723

Integrative Genomic Analysis of Coincident Cancer Foci Implicates CTNNB1 and PTEN Alterations in Ductal Prostate Cancer.

PubMed

Gillard, Marc; Lack, Justin; Pontier, Andrea; Gandla, Divya; Hatcher, David; Sowalsky, Adam G; Rodriguez-Nieves, Jose; Vander Griend, Donald; Paner, Gladell; VanderWeele, David

2017-12-08

Ductal adenocarcinoma of the prostate is an aggressive subtype, with high rates of biochemical recurrence and overall poor prognosis. It is frequently found coincident with conventional acinar adenocarcinoma. The genomic features driving evolution to its ductal histology and the biology associated with its poor prognosis remain unknown. To characterize genomic features distinguishing ductal adenocarcinoma from coincident acinar adenocarcinoma foci from the same patient. Ten patients with coincident acinar and ductal prostate cancer underwent prostatectomy. Laser microdissection was used to separately isolate acinar and ductal foci. DNA and RNA were extracted, and used for integrative genomic and transcriptomic analyses. Single nucleotide mutations, small indels, copy number estimates, and expression profiles were identified. Phylogenetic relationships between coincident foci were determined, and characteristics distinguishing ductal from acinar foci were identified. Exome sequencing, copy number estimates, and fusion genes demonstrated coincident ductal and acinar adenocarcinoma diverged from a common progenitor, yet they harbored distinct alterations unique to each focus. AR expression and activity were similar in both histologies. Nine of 10 cases had mutually exclusive CTNNB1 hotspot mutations or phosphatase and tensin homolog (PTEN) alterations in the ductal component, and these were absent in the acinar foci. These alterations were associated with changes in expression in WNT- and PI3K-pathway genes. Coincident ductal and acinar histologies typically are clonally related and thus arise from the same cell of origin. Ductal foci are enriched for cases with either a CTNNB1 hotspot mutation or a PTEN alteration, and are associated with WNT- or PI3K-pathway activation. These alterations are mutually exclusive and may represent distinct subtypes. The aggressive subtype ductal adenocarcinoma is closely related to conventional acinar prostate cancer. Ductal foci

On determining dose rate constants spectroscopically.

PubMed

Rodriguez, M; Rogers, D W O

2013-01-01

To investigate several aspects of the Chen and Nath spectroscopic method of determining the dose rate constants of (125)I and (103)Pd seeds [Z. Chen and R. Nath, Phys. Med. Biol. 55, 6089-6104 (2010)] including the accuracy of using a line or dual-point source approximation as done in their method, and the accuracy of ignoring the effects of the scattered photons in the spectra. Additionally, the authors investigate the accuracy of the literature's many different spectra for bare, i.e., unencapsulated (125)I and (103)Pd sources. Spectra generated by 14 (125)I and 6 (103)Pd seeds were calculated in vacuo at 10 cm from the source in a 2.7 × 2.7 × 0.05 cm(3) voxel using the EGSnrc BrachyDose Monte Carlo code. Calculated spectra used the initial photon spectra recommended by AAPM's TG-43U1 and NCRP (National Council of Radiation Protection and Measurements) Report 58 for the (125)I seeds, or TG-43U1 and NNDC(2000) (National Nuclear Data Center, 2000) for (103)Pd seeds. The emitted spectra were treated as coming from a line or dual-point source in a Monte Carlo simulation to calculate the dose rate constant. The TG-43U1 definition of the dose rate constant was used. These calculations were performed using the full spectrum including scattered photons or using only the main peaks in the spectrum as done experimentally. Statistical uncertainties on the air kerma/history and the dose rate/history were ≤0.2%. The dose rate constants were also calculated using Monte Carlo simulations of the full seed model. The ratio of the intensity of the 31 keV line relative to that of the main peak in (125)I spectra is, on average, 6.8% higher when calculated with the NCRP Report 58 initial spectrum vs that calculated with TG-43U1 initial spectrum. The (103)Pd spectra exhibit an average 6.2% decrease in the 22.9 keV line relative to the main peak when calculated with the TG-43U1 rather than the NNDC(2000) initial spectrum. The measured values from three different investigations are

Low-Dose Radiation Cataract and Genetic Determinants of Radiosensitivity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kleiman, Norman Jay

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

Triple negative breast tumors in African-American and Hispanic/Latina women are high in CD44+, low in CD24+, and have loss of PTEN.

PubMed

Wu, Yanyuan; Sarkissyan, Marianna; Elshimali, Yahya; Vadgama, Jaydutt V

2013-01-01

African-American women have higher mortality from breast cancer than other ethnic groups. The association between poor survival and differences with tumor phenotypes is not well understood. The purpose of this study is to assess the clinical significance of (1) Stem cell-like markers CD44 and CD24; (2) PI3K/Akt pathway associated targets PTEN, activation of Akt, and FOXO1; and (3) the Insulin-like growth factor-1 (IGF-I) and IGF binding protein-3 (IGFBP3) in different breast cancer subtypes, and compare the differences between African-American and Hispanic/Latina women who have similar social-economic-status. A total of N=318 African-American and Hispanic/Latina women, with clinically-annotated information within the inclusion criteria were included. Formalin fixed paraffin embedded tissues from these patients were tested for the different markers using immunohistochemistry techniques. Kaplan-Meier survival-curves and Cox-regression analyses were used to assess Relative Risk and Disease-Free-Survival (DFS). The triple-negative-breast-cancer (TNBC) receptor-subtype was more prevalent among premenopausal women, and the Hormonal Receptor (HR) positive subtype was most common overall. TNBC tumors were more likely to have loss of PTEN, express high Ki67, and have increased CD44+/CD24- expression. TNBC was also associated with higher plasma-IGF-I levels. HR-/HER2+ tumors showed high pAkt, decreased FOXO1, and high CD24+ expression. The loss of PTEN impacted DFS significantly in African Americans, but not in Hispanics/Latinas after adjusted for treatment and other tumor pathological factors. The CD44+/CD24- and CD24+/CD44- phenotypes decreased DFS, but were not independent predictors for DFS. HER2-positive and TNBC type of cancers continued to exhibit significant decrease in DFS after adjusting for the selected biomarkers and treatment. TNBC incidence is high among African-American and Hispanic/Latino women residing in South Los Angeles. Our study also shows for the first

On determining dose rate constants spectroscopically

DOE Office of Scientific and Technical Information (OSTI.GOV)

Rodriguez, M.; Rogers, D. W. O.

2013-01-15

Purpose: To investigate several aspects of the Chen and Nath spectroscopic method of determining the dose rate constants of {sup 125}I and {sup 103}Pd seeds [Z. Chen and R. Nath, Phys. Med. Biol. 55, 6089-6104 (2010)] including the accuracy of using a line or dual-point source approximation as done in their method, and the accuracy of ignoring the effects of the scattered photons in the spectra. Additionally, the authors investigate the accuracy of the literature's many different spectra for bare, i.e., unencapsulated {sup 125}I and {sup 103}Pd sources. Methods: Spectra generated by 14 {sup 125}I and 6 {sup 103}Pd seedsmore » were calculated in vacuo at 10 cm from the source in a 2.7 Multiplication-Sign 2.7 Multiplication-Sign 0.05 cm{sup 3} voxel using the EGSnrc BrachyDose Monte Carlo code. Calculated spectra used the initial photon spectra recommended by AAPM's TG-43U1 and NCRP (National Council of Radiation Protection and Measurements) Report 58 for the {sup 125}I seeds, or TG-43U1 and NNDC(2000) (National Nuclear Data Center, 2000) for {sup 103}Pd seeds. The emitted spectra were treated as coming from a line or dual-point source in a Monte Carlo simulation to calculate the dose rate constant. The TG-43U1 definition of the dose rate constant was used. These calculations were performed using the full spectrum including scattered photons or using only the main peaks in the spectrum as done experimentally. Statistical uncertainties on the air kerma/history and the dose rate/history were Less-Than-Or-Slanted-Equal-To 0.2%. The dose rate constants were also calculated using Monte Carlo simulations of the full seed model. Results: The ratio of the intensity of the 31 keV line relative to that of the main peak in {sup 125}I spectra is, on average, 6.8% higher when calculated with the NCRP Report 58 initial spectrum vs that calculated with TG-43U1 initial spectrum. The {sup 103}Pd spectra exhibit an average 6.2% decrease in the 22.9 keV line relative to the main peak

How accurately can the peak skin dose in fluoroscopy be determined using indirect dose metrics?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jones, A. Kyle, E-mail: kyle.jones@mdanderson.org; Ensor, Joe E.; Pasciak, Alexander S.

Purpose: Skin dosimetry is important for fluoroscopically-guided interventions, as peak skin doses (PSD) that result in skin reactions can be reached during these procedures. There is no consensus as to whether or not indirect skin dosimetry is sufficiently accurate for fluoroscopically-guided interventions. However, measuring PSD with film is difficult and the decision to do so must be madea priori. The purpose of this study was to assess the accuracy of different types of indirect dose estimates and to determine if PSD can be calculated within ±50% using indirect dose metrics for embolization procedures. Methods: PSD were measured directly using radiochromicmore » film for 41 consecutive embolization procedures at two sites. Indirect dose metrics from the procedures were collected, including reference air kerma. Four different estimates of PSD were calculated from the indirect dose metrics and compared along with reference air kerma to the measured PSD for each case. The four indirect estimates included a standard calculation method, the use of detailed information from the radiation dose structured report, and two simplified calculation methods based on the standard method. Indirect dosimetry results were compared with direct measurements, including an analysis of uncertainty associated with film dosimetry. Factors affecting the accuracy of the different indirect estimates were examined. Results: When using the standard calculation method, calculated PSD were within ±35% for all 41 procedures studied. Calculated PSD were within ±50% for a simplified method using a single source-to-patient distance for all calculations. Reference air kerma was within ±50% for all but one procedure. Cases for which reference air kerma or calculated PSD exhibited large (±35%) differences from the measured PSD were analyzed, and two main causative factors were identified: unusually small or large source-to-patient distances and large contributions to reference air kerma from

Inhibition of AMPK and Krebs cycle gene expression drives metabolic remodeling of Pten-deficient preneoplastic thyroid cells.

PubMed

Antico Arciuch, Valeria G; Russo, Marika A; Kang, Kristy S; Di Cristofano, Antonio

2013-09-01

Rapidly proliferating and neoplastically transformed cells generate the energy required to support rapid cell division by increasing glycolysis and decreasing flux through the oxidative phosphorylation (OXPHOS) pathway, usually without alterations in mitochondrial function. In contrast, little is known of the metabolic alterations, if any, which occur in cells harboring mutations that prime their neoplastic transformation. To address this question, we used a Pten-deficient mouse model to examine thyroid cells where a mild hyperplasia progresses slowly to follicular thyroid carcinoma. Using this model, we report that constitutive phosphoinositide 3-kinase (PI3K) activation caused by PTEN deficiency in nontransformed thyrocytes results in a global downregulation of Krebs cycle and OXPHOS gene expression, defective mitochondria, reduced respiration, and an enhancement in compensatory glycolysis. We found that this process does not involve any of the pathways classically associated with the Warburg effect. Moreover, this process was independent of proliferation but contributed directly to thyroid hyperplasia. Our findings define a novel metabolic switch to glycolysis driven by PI3K-dependent AMPK inactivation with a consequent repression in the expression of key metabolic transcription regulators. ©2013 AACR.

Maximum dose rate is a determinant of hypothyroidism after 131I therapy of Graves' disease but the total thyroid absorbed dose is not.

PubMed

Krohn, Thomas; Hänscheid, Heribert; Müller, Berthold; Behrendt, Florian F; Heinzel, Alexander; Mottaghy, Felix M; Verburg, Frederik A

2014-11-01

The determinants of successful (131)I therapy of Graves' disease (GD) are unclear. To relate dosimetry parameters to outcome of therapy to identify significant determinants eu- and/or hypothyroidism after (131)I therapy in patients with GD. A retrospective study in which 206 Patients with GD treated in University Hospital between November 1999 and January 2011. All received (131)I therapy aiming at a total absorbed dose to the thyroid of 250 Gy based on pre-therapeutic dosimetry. Post-therapy dosimetric thyroid measurements were performed twice daily until discharge. From these measurements, thyroid (131)I half-life, the total thyroid absorbed dose, and the maximum dose rate after (131)I administration were calculated. In all, 48.5% of patients were hypothyroid and 28.6% of patients were euthyroid after (131)I therapy. In univariate analysis, nonhyperthyroid and hyperthyroid patients only differed by sex. A lower thyroid mass, a higher activity per gram thyroid tissue, a shorter effective thyroidal (131)I half-life, and a higher maximum dose rate, but not the total thyroid absorbed dose, were significantly associated with hypothyroidism. In multivariate analysis, the maximum dose rate remained the only significant determinant of hypothyroidism (P < .001). Maximum dose rates of 2.2 Gy/h and higher were associated with a 100% hypothyroidism rate. Not the total thyroid absorbed dose, but the maximum dose rate is a determinant of successfully achieving hypothyroidism in Graves' disease. Dosimetric concepts aiming at a specific total thyroid absorbed dose will therefore require reconsideration if our data are confirmed prospectively.

Tangeretin induces cell cycle arrest and apoptosis through upregulation of PTEN expression in glioma cells.

PubMed

Ma, Li-Li; Wang, Da-Wei; Yu, Xu-Dong; Zhou, Yan-Ling

2016-07-01

Tangeretin (TANG), present in peel of citrus fruits, has been shown to various medicinal properties such as chemopreventive and neuroprotective. However, the chemopreventive effect of TANG on glioblastoma cells has not been examined. The present study was designed to explore the anticancer potential of TANG in glioblastoma cells and to investigate the related mechanism. Human glioblastoma U-87MG and LN-18 cells were treated with 45μM concentration of TANG and cell growth was measured by MTT assay. The cell cycle distribution and cell death were measured by flow cytometry. The expression of cell cycle and apoptosis related genes were analyzed by quantitative RT-PCR and western blot. The cells treated with TANG were significantly increased cell growth suppression and cell death effects than vehicle treated cells. Further, TANG treatment increases G2/M arrest and apoptosis by modulating PTEN and cell-cycle regulated genes such as cyclin-D and cdc-2 mRNA and protein expressions. Moreover, the ability of TANG to decrease cell growth and to induce cell death was compromised when PTEN was knockdown by siRNA. Taken together, the chemopreventive effect of TANG is associated with regulation of cell-cycle and apoptosis in glioblastoma, thereby attenuating glioblastoma cell growth. Hence, the present findings suggest that TANG may be a therapeutic agent for glioblastoma treatment. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Concurrent BRAF and PTEN mutations in melanoma of unknown origin presenting as a breast mass

PubMed Central

Agosto-Arroyo, Emmanuel; Rosa, Marilin; Chau, Alec; Khazai, Laila

2017-01-01

Background: Metastases represent a small percentage of the malignancies affecting the breast, and only 5% of melanomas originate from non-cutaneous sites. Multiple genetic aberrations have been associated with the development of melanocytic lesions, including BRAF V600E mutation. Mutations in PTEN gene have also been related to the pathogenesis of multiple malignancies. Purpose/Method: This is the case of a 28-year-old female who presented with a tender, palpable mass in the upper outer quadrant of the right breast. Ultrasound showed a 1-cm solid mass, initially diagnosed as invasive ductal carcinoma on biopsy. During pre-operative workup, a second mass was identified and biopsied. Immunohistochemical stains performed on the second mass biopsy demonstrated that the neoplastic cells were positive for cytokeratin AE1/3, pan-melanoma, tyrosinase, and SOX-10 and negative for CK7, CAM5.2, and GATA-3. Subsequent workup showed widespread metastatic disease involving the liver, lungs, bones, and brain. The brain metastasis tested positive for BRAF p.V600E and PTEN p.R130Efs*4 mutations. Thorough skin and eye examination did not reveal a primary melanoma. Conclusion: Only few reports have been published of melanoma presenting as a breast mass. This is an interesting case due to the clinical presentation, diagnostic challenges, and genetic mutations profile. PMID:28607685

The 5-lipoxygenase inhibitor tepoxalin induces oxidative damage and altered PTEN status prior to apoptosis in canine osteosarcoma cell lines.

PubMed

Loftus, J P; Cavatorta, D; Bushey, J J; Levine, C B; Sevier, C S; Wakshlag, J J

2016-06-01

The 5-lipoxygenase (5-LOX) inhibitor tepoxalin has been shown to slow canine osteosarcoma (OSA) tumour xenografts growth, yet the mechanisms are poorly elucidated. Further examination of tepoxalin in canine OSA cell lines shows that tepoxalin treated cells undergo apoptosis through caspase-3 activation and annexin staining. Interestingly, apoptosis is superseded by an increase in reactive oxygen species (ROS), as measured by activation of dihydrorhodamine 123 and mitosox. This increase in ROS appears to be related to the 5-LOX inhibitor regardless of cellular 5-LOX status, and was not observed after treatment with the tepoxalin metabolite RWJ20142. Additionally, 5-LOX inhibition by tepoxalin appears to increase phosphatase and tensin (PTEN) homolog activity by preventing its alkylation or oxidation. PTEN modification or inhibition allows phosphoinositide-3 (PI3) kinase activity thereby heightening activation of protein kinase B (AKT) phosphorylation. Our data suggest that off target oxidation and LOX inhibition play roles in the apoptotic response. © 2014 John Wiley & Sons Ltd.

Differential IKK/NF-κB Activity is Mediated by TSC2 through mTORC1 in PTEN-null Prostate Cancer and Tuberous Sclerosis Complex Tumor Cells

PubMed Central

Gao, Yu; Gartenhaus, Ronald B.; Lapidus, Rena G.; Hussain, Arif; Zhang, Yanting; Wang, Xinghuan; Dan, Han C.

2015-01-01

The serine/threonine protein kinase Akt plays a critical role in regulating proliferation, growth and survival through phosphorylation of different downstream substrates. The mammalian target of rapamycin (mTOR) is a key target for Akt to promote tumorigenesis. It has been reported that Akt activates mTOR through phosphorylation and inhibition of the tuberous sclerosis complex (TSC) protein TSC2. Previously it was demonstrated that mTOR activates IKK/NF-κB signaling by promoting IKK activity downstream of Akt in conditions deficient of PTEN. In the current study, the mechanistic role of the tumor suppressor TSC2 was investigated in the regulation of IKK/NF-κB activity in PTEN-null prostate cancer and in TSC2 mutated tumor cells. The results demonstrate that TSC2 inhibits IKK/NF-κB activity downstream of Akt and upstream of mTORC1 in a PTEN deficient environment. However, TSC2 promotes IKK/NF-κB activity upstream of Akt and mTORC1 in TSC2 mutated tumor cells. These data indicate that TSC2 negatively or positively regulates IKK/NF-κB activity in a context-dependent manner depending on the genetic background. PMID:26374334

Correlation analysis of expressions of PTEN and p53 with the value obtained by magnetic resonance spectroscopy and apparent diffusion coefficient in the tumor and the tumor-adjacent area in magnetic resonance imaging for glioblastoma.

PubMed

Li, Yunyun; Ji, Feng; Jiang, Yuzhi; Zhao, Ting; Xu, Chongfu

2018-01-01

To explore the correlation of the expression levels of phosphate and tension homology deleted on chromosome ten (PTEN) and p53 of glioblastoma multiforme (GBM) with the value obtained by magnetic resonance spectroscopy (MRS) and apparent diffusion coefficient (ADC) in the tumor and the tumor-adjacent area in magnetic resonance imaging (MRI). A total of 38 patients were operated for GBM. All the patients had received diffusion-weighted imaging (DWI) and MRS prior to surgery. ADC of water molecules and values of metabolite indexes of MRS, including n-acetyl aspartate (NAA), choline (Cho) and creatine (Cr), were recorded, and the ratios of Cho/NAA, Cho/Cr and NAA/Cr were calculated. Hematoxylin-eosin (H&E) staining was done to examine the morphology of tumor and of tumor-adjacent tissues; immunohistochemistry (IHC) was performed to examine the expressions of PTEN and p53 in the tumor and the tumor-adjacent area. Finally, the correlations of the expressions of PTEN and p53 with ADC, Cho/NAA, Cho/Cr and NAA/Cr of the tumor and the tumor-adjacent area were analyzed. H&E staining showed that GBM tissues had disordered morphology, different sizes of cells, large cell nuclei and significant cell heterogeneity. IHC indicated that the expression level of p53 protein in the tumor was significantly higher than in the tumor-adjacent tissues (p<0.05). The expression level of PTEN protein was high in the tumor-adjacent tissues, but significantly deficient in the tumor. DWI showed that the signal of DWI in the tumor was significantly increased, but ADC was decreased compared with the tumor-adjacent area. MRS indicated that the wave band of Cho in the tumor was significantly increased, NAA was significantly lowered, and Cr section was decreased compared with the tumor-adjacent area, while NAA/Cr in the tumor was significantly decreased compared with the tumoradjacent area (p<0.05). Correlation analysis indicated that PTEN levels in the tumor and the tumor-adjacent area were

MicroRNA-300 Regulates the Ubiquitination of PTEN through the CRL4BDCAF13 E3 Ligase in Osteosarcoma Cells.

PubMed

Chen, Zhi; Zhang, Wei; Jiang, Kaibiao; Chen, Bin; Wang, Kun; Lao, Lifeng; Hou, Canglong; Wang, Fei; Zhang, Caiguo; Shen, Hongxing

2018-03-02

Cullins, critical members of the cullin-RING ubiquitin ligases (CRLs), are often aberrantly expressed in different cancers. However, the underlying mechanisms regarding aberrant expression of these cullins and the specific substrates of CRLs in different cancers are mostly unknown. Here, we demonstrate that overexpressed CUL4B in human osteosarcoma cells forms an E3 complex with DNA damage binding protein 1 (DDB1) and DDB1- and CUL4-associated factor 13 (DCAF13). In vitro and in vivo analyses indicated that the CRL4B DCAF13 E3 ligase specifically recognized the tumor suppressor PTEN (phosphatase and tensin homolog deleted on chromosome 10) for degradation, and disruption of this E3 ligase resulted in PTEN accumulation. Further analyses indicated that miR-300 directly targeted the 3' UTR of CUL4B, and DNA hypermethylation of a CpG island in the miR-300 promoter region contributed to the downregulation of miR-300. Interestingly, ectopic expression of miR-300 or treatment with 5-AZA-2'-deoxycytidine, a DNA methylation inhibitor, decreased the stability of CRL4B DCAF13 E3 ligase and reduced PTEN ubiquitination. By applying in vitro screening to identify small molecules that specifically inhibit CUL4B-DDB1 interaction, we found that TSC01131 could greatly inhibit osteosarcoma cell growth and could disrupt the stability of the CRL4B DCAF13 E3 ligase. Collectively, our findings shed new light on the molecular mechanism of CUL4B function and might also provide a new avenue for osteosarcoma therapy. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

Arid1a Inactivation in an Apc and Pten-defective Mouse Ovarian Cancer Model Enhances Epithelial Differentiation and Prolongs Survival

PubMed Central

Zhai, Yali; Kuick, Rork; Tipton, Courtney; Wu, Rong; Sessine, Michael; Wang, Zhong; Baker, Suzanne J.; Fearon, Eric R.; Cho, Kathleen R.

2015-01-01

Inactivation of the ARID1A tumor suppressor gene is frequent in ovarian endometrioid (OEC) and clear cell carcinomas (OCCC), often in conjunction with mutations activating the PI3K/AKT and/or canonical Wnt signaling pathways. Prior work has shown that conditional bi-allelic inactivation of the Apc and Pten tumor suppressor genes in the mouse ovarian surface epithelium (OSE) promotes outgrowth of tumors that reflect the biological behavior and gene expression profiles of human OECs harboring comparable Wnt and PI3K/AKT pathway defects, though the mouse tumors are more poorly differentiated than their human tumor counterparts. We found that conditional inactivation of one or both Arid1a alleles in OSE concurrently with Apc and Pten inactivation unexpectedly prolonged survival of tumor-bearing mice and promoted striking epithelial differentiation of the cancer cells, resulting in morphological features akin to those in human OECs. Enhanced epithelial differentiation was linked to reduced expression of mesenchymal markers N-cadherin and vimentin, and increased expression of epithelial markers Crb3 and E-cadherin. Global gene expression profiling showed enrichment for genes associated with mesenchymal-to-epithelial transition in the Arid1a-deficient tumors. We also found that an activating (E545K) Pik3ca mutation, unlike Pten inactivation or Pik3ca H1047R mutation, cannot cooperate with Arid1a loss to promote ovarian cancer development in the mouse. Our results indicate the Arid1a tumor suppressor gene has a key role in regulating OEC differentiation, and paradoxically the mouse cancers with more initiating tumor suppressor gene defects had a less aggressive phenotype than cancers arising from fewer gene alterations. PMID:26279473

Determination of effective doses in image-guided radiation therapy system

NASA Astrophysics Data System (ADS)

Pyone, Y. Y.; Suriyapee, S.; Sanghangthum, T.; Oonsiri, S.; Tawonwong, T.

2016-03-01

The organ and effective doses in image-guided radiotherapy system are determined in this study. For 2D imaging, incident air kerma (Ki) was measured by 6cc ionization chamber with Accu-Pro dosimeter. The entrance surface air kerma (ESAK) was calculated by multiplying Ki with backscatter factor. The effective dose was calculated by multiplying ESAK with conversion coefficient. For 3D imaging, computed tomography/cone-beam dose index (CTDI/CBDI) measurements were performed by using 100mm pencil ionization chamber with Accu-Pro dosimeter. The dose index in air and in CTDI phantom from planning CT and cone- beam CT were measured. Then, effective dose was calculated by ImPACT software. The effective doses from 2D conventional simulator for anteroposterior and lateral projections were 01 and 0.02mSv for head, 0.15 and 0.16mSv for thorax, 0.22 and 0.21mSv for pelvis, respectively. The effective doses from 3D, planning CT and CBCT, were 3.3 and 0.1mSv for head, 13 and 2.4mSv for thorax and 7.2 and 4.9mSv for pelvis, respectively. Based on 30 fractions of treatment course, total effective dose (3D CT, 2D setup verification and 6 times CBCT) of head, thorax and pelvis were 3.93, 27.71 and 37.03mSv, respectively. Therefore, IGRT should be administered with significant parameters to reduce the dose.

[Expression of miR-21 and Its Acat1, Armcx1, and Pten Target Genes in Liver of Female Rats Treated with DDT and Benzo[a]pyrene].

PubMed

Chanyshev, M D; Ushakov, D S; Gulyaeva, L F

2017-01-01

MiR-21 is the most studied cancer-promoting oncomiR, which target numerous tumor suppressor genes associated with proliferation, apoptosis, and invasion. Here we have studied the synthesis of miR-21 and quantified the mRNA and protein levels for miR-21 potential target genes, i.e., Acat1, Armcx1, and Pten, in the livers of female Wistar rats after their treatment with either 1,1-trichloro-2,2-di(4-chlorophenyl)ethane (DDT) or benzo[a]pyrene (BP). The most important finding appears to be the significant decrease in the miR-21 level the day after treatment with DDT with subsequent rebound. These changes are accompanied by an increase and subsequent drop in the levels of mRNAs and proteins of the Acat1, Armcx1, and Pten genes. These observations indicate the involvement of miR-21 in the posttranscriptional regulation of the Acat1, Armcx1, and Pten genes in response to xenobiotics. We hypothesize that the toxic effects of xenobiotics may be indirect and may manifest by inducing epigenetic changes, particularly through the regulation of miRNAs and their target genes.

miR-494 up-regulates the PI3K/Akt pathway via targetting PTEN and attenuates hepatic ischemia/reperfusion injury in a rat model.

PubMed

Su, Song; Luo, De; Liu, Xiangdong; Liu, Jiang; Peng, Fangyi; Fang, Cheng; Li, Bo

2017-10-31

A rat HIRI model was constructed and treated with an intraperitoneal injection of agomir- miR-494 or agomir-NC (negative control) for 7 days after the surgery. The pathophysiological changes in sham-operated rats, HIRI, HIRI + agomir- miR-494 , and HIRI + agomir-NC were compared. The effect of miR-494 was also assessed in an H 2 O 2 -induced apoptosis model. Hepatic AML12 cells were transfected with mimics NC or miR-494 mimics, followed by 6-h H 2 O 2 treatment. Cell proliferation and apoptosis were detected by CCK8 assay and flow cytometry, respectively. Further, the miR-494 target gene was identified by luciferase reporter assay, and verified both in vitro and in vivo experiments. The activity of AKT pathway was further analyzed in vivo by Western blot. HIRI + agomir- miR-494 rats exhibited significantly higher miR-494 expression, lower serum alanine aminotransferase (ALT), aspartate aminotransferase (AST), lactate dehydrogenase (LDH), and glutamate dehydrogenase (GLDH) level, lower hepatic MDA, TOA, and OSI, alleviated hepatic necrosis, reduced hepatocyte apoptosis, and decreased expression of apoptosis-related proteins, when compared with HIRI + agomir-NC rats ( P <0.05 or 0.01). After H 2 O 2 treatment, AML-12 cells transfected with miR-494 mimics had significantly higher proliferation and lower apoptosis rate compared with mimics NC group ( P <0.01). PTEN was identified as an miR-494 target gene. PTEN expression was significantly down-regulated in AML12 cells transfected with miR-494 mimics, and was up-regulated by treatment of miR-494 inhibitor ( P <0.01). Moreover, HIRI + agomir- miR-494 rats exhibited significantly lower PTEN expression, and higher p-AKT, p-mTOR, and p-p70S6K levels compared with HIRI + agomir-NC rats. Therefore, miR-494 protected rats against hepatic ischemia/reperfusion (I/R) injury through down-regulating its downstream target gene PTEN , leading to the activation of PI3K/AKT signaling pathway. © 2017 The Author(s).

Differential Requirements for c-Myc in Chronic Hematopoietic Hyperplasia and Acute Hematopoietic Malignancies in Pten-null Mice

PubMed Central

Zhang, Jun; Xiao, Yechen; Guo, Yinshi; Breslin, Peter; Zhang, Shubin; Wei, Wei; Zhang, Zhou; Zhang, Jiwang

2011-01-01

Myeloproliferative disorders (MPDs), lymphoproliferative disorders (LPDs), acute T-lymphocytic or myeloid leukemia and T-lymphocytic lymphoma were developed in inducible Pten-knockout (Pten−/−) mice. The appearance of these multiple diseases in one animal model provides an opportunity to study the pathogenesis of multiple diseases simultaneously. To study whether Myc function is required for the development of these hematopoietic disorders in Pten−/− mice, we generated inducible Pten/Myc double-knockout mice (Pten−/−/Myc−/−). By comparing the hematopoietic phenotypes of these double-knockout mice with those of Pten−/− mice, we found that both sets of animals developed MPDs and LPDs. However, none of the compound-mutant mice developed acute leukemia or lymphoma. Interestingly, in contrast to the MPDs which developed in Pten−/− mice which are dominated by granulocytes, megakaryocytes predominate in the MPDs of Pten−/−/Myc−/− mice. Our study suggests that the deregulation of PI3K/Akt signaling in Pten−/− hematopoietic cells protects these cells from apoptotic cell death, resulting in chronic proliferative disorders. But due to the differential requirement for Myc in granulocyte as compared to megakaryocyte proliferation, Myc deletion converts Pten−/− MPDs from granulocyte-dominated to megakaryocyte-dominated conditions. Myc is absolutely required for the development of acute hematopoietic malignancies. PMID:21926961

Tramadol regulates proliferation, migration and invasion via PTEN/PI3K/AKT signaling in lung adenocarcinoma cells.

PubMed

Xia, M; Tong, J-H; Ji, N-N; Duan, M-L; Tan, Y-H; Xu, J-G

2016-06-01

Tramadol is used mainly for the treatment of moderate to severe chronic cancer pain. However, the effect of tramadol on lung cancer remains unclear. Therefore, it is important to explore the mechanism accounting for the function of tramadol on lung cancer. We investigated the effects of tramadol on the proliferation, migration and invasion in human lung adenocarcinoma cells in vitro by CCK-8 assay, wound healing assay and Transwell assay, respectively. We also explored the potential mechanism of tramadol on lung cancer cells by Western blotting. A549 and PC-9 cells were incubated with 2 µM tramadol for different time (0, 7, 14 and 28 d). The in vitro experiments showed that tramadol treatment significantly inhibited cell proliferation, migration and invasion in a time-dependent manner. Moreover, administration of tramadol suppressed tumor growth in vivo. The data also revealed that tramadol could up-regulate the protein expression level of PTEN and consistently inhibit the phosphorylation level of PI3K and Akt, whereas the total level of PI3K and Akt remain unchanged. These findings indicated that tramadol inhibited proliferation, migration and invasion of human lung adenocarcinoma cells through elevation of PTEN and inactivation of PI3K/Akt signaling.

α(V)β(6) integrin expression is induced in the POET and Pten(pc-/-) mouse models of prostatic inflammation and prostatic adenocarcinoma.

PubMed

Garlick, David S; Li, Jing; Sansoucy, Brian; Wang, Tao; Griffith, Leeanne; Fitzgerald, Tj; Butterfield, Julie; Charbonneau, Bridget; Violette, Shelia M; Weinreb, Paul H; Ratliff, Timothy L; Liao, Chun-Peng; Roy-Burman, Pradip; Vietri, Michele; Lian, Jane B; Stein, Gary S; Altieri, Dario C; Languino, Lucia R

2012-01-01

Chronic inflammation is proposed to prime the development of prostate cancer. However, the mechanisms of prostate cancer initiation and development are not completely understood. The α(v)β(6) integrin has been shown to play a role in epithelial development, wound healing and some epithelial cancers [1, 2]. Here, we investigate the expression of α(v)β(6) in mouse models of prostatic inflammation and prostate cancer to establish a possible relationship between inflammation of the prostate, α(v)β(6) expression and the progression of prostate cancer. Using immunohistochemical techniques, we show expression of α(v)β(6) in two in vivo mouse models; the Pten(pc)-/- model containing a prostate- specific Pten tumor suppressor deletion that causes cancer, and the prostate ovalbumin-expressing transgenic (POET) inflammation mouse model. We show that the α(v)β(6) integrin is induced in prostate cancer and inflammation in vivo in these two mouse models. α(v)β(6) is expressed in all the mice with cancer in the Pten(pc-/-) model but not in age-matched wild-type mice. In the POET inflammation model, α(v)β(6) is expressed in mice injected with activated T-cells, but in none of the control mice. In the POET model, we also used real time PCR to assess the expression of Transforming Growth Factor Beta 1 (TGFβ1), a factor in inflammation that is activated by α(v)β(6). In conclusion, through in vivo evidence, we conclude that α(v)β(6) integrin may be a crucial link between prostatic inflammation and prostatic adenocarcinoma.

Cooperation between both Wnt/β-catenin and PTEN/PI3K/Akt signaling promotes primitive hematopoietic stem cell self-renewal and expansion

PubMed Central

Perry, John M.; He, Xi C.; Sugimura, Ryohichi; Grindley, Justin C.; Haug, Jeffrey S.; Ding, Sheng; Li, Linheng

2011-01-01

Although self-renewal is the central property of stem cells, the underlying mechanism remains inadequately defined. Using a hematopoietic stem and progenitor cell (HSPC)-specific conditional induction line, we generated a compound genetic model bearing both Pten deletion and β-catenin activation. These double mutant mice exhibit a novel phenotype, including expansion of phenotypic long-term hematopoietic stem cells (LT-HSCs) without extensive differentiation. Unexpectedly, constitutive activation of β-catenin alone results in apoptosis of HSCs. However, together, the Wnt/β-catenin and PTEN/PI3k/Akt pathways interact to drive phenotypic LT-HSC expansion by inducing proliferation while simultaneously inhibiting apoptosis and blocking differentiation, demonstrating the necessity of complementary cooperation between the two pathways in promoting self-renewal. Mechanistically, β-catenin activation reduces multiple differentiation-inducing transcription factors, blocking differentiation partially through up-regulation of Inhibitor of differentiation 2 (Id2). In double mutants, loss of Pten enhances the HSC anti-apoptotic factor Mcl-1. All of these contribute in a complementary way to HSC self-renewal and expansion. While permanent, genetic alteration of both pathways in double mutant mice leads to expansion of phenotypic HSCs, these HSCs cannot function due to blocked differentiation. We developed a pharmacological approach to expand normal, functional HSCs in culture using factors that reversibly activate both Wnt/β-catenin and PI3K/Akt signaling simultaneously. We show for the first time that activation of either single pathway is insufficient to expand primitive HSCs, but in combination, both pathways drive self-renewal and expansion of HSCs with long-term functional capacity. PMID:21890648

Downregulation of PI3-K/Akt/PTEN pathway and activation of mitochondrial intrinsic apoptosis by Diclofenac and Curcumin in colon cancer.

PubMed

Rana, Chandan; Piplani, Honit; Vaish, Vivek; Nehru, Bimla; Sanyal, S N

2015-04-01

Phosphatidylinositol 3-kinase (PI3-K)/PTEN/Akt signaling is over activated in various tumors including colon cancer. Activation of this pathway regulates multiple biological processes such as apoptosis, metabolism, cell proliferation, and cell growth that underlie the biology of a cancer cell. In the present study, the chemopreventive effects have been observed of Diclofenac, a preferential COX-2 inhibitory non-steroidal anti-inflammatory drugs, and Curcumin, a natural anti-inflammatory agent, in the early stage of colorectal carcinogenesis induced by 1,2-dimethylhydrazine dihydrochloride in rats. The tumor-promoting role of PI3-K/Akt/PTEN signal transduction pathway and its association with anti-apoptotic family of proteins are also observed. Both Diclofenac and Curcumin downregulated the PI3-K and Akt expression while promoting the apoptotic mechanism. Diclofenac and Curcumin administration significantly increased the expression of pro-apoptotic Bcl-2 family members (Bad and Bax) while decreasing the anti-apoptotic Bcl-2 protein. An up-regulation of cysteine protease family apoptosis executioner, such as caspase-3 and -9, is seen. Diclofenac and Curcumin inhibited the Bcl-2 protein by directly interacting at the active site by multiple hydrogen bonding, as also evident by negative glide score of Bcl-2. These drugs stimulated apoptosis by increasing reactive oxygen species (ROS) generation and simultaneously decreasing the mitochondrial membrane potential (ΔΨ M). Diclofenac and Curcumin showed anti-neoplastic effects by downregulating PI3-K/Akt/PTEN pathway, inducing apoptosis, increasing ROS generation, and decreasing ΔΨ M. The anti-neoplastic and apoptotic effects were found enhanced when both Diclofenac and Curcumin were administered together, rather than individually.

Specific gene expression signatures induced by the multiple oncogenic alterations that occur within the PTEN/PI3K/AKT pathway in lung cancer.

PubMed

De Marco, Carmela; Laudanna, Carmelo; Rinaldo, Nicola; Oliveira, Duarte Mendes; Ravo, Maria; Weisz, Alessandro; Ceccarelli, Michele; Caira, Elvira; Rizzuto, Antonia; Zoppoli, Pietro; Malanga, Donatella; Viglietto, Giuseppe

2017-01-01

Hyperactivation of the phosphatydil-inositol-3' phosphate kinase (PI3K)/AKT pathway is observed in most NSCLCs, promoting proliferation, migration, invasion and resistance to therapy. AKT can be activated through several mechanisms that include loss of the negative regulator PTEN, activating mutations of the catalytic subunit of PI3K (PIK3CA) and/or mutations of AKT1 itself. However, number and identity of downstream targets of activated PI3K/AKT pathway are poorly defined. To identify the genes that are targets of constitutive PI3K/AKT signalling in lung cancer cells, we performed a comparative transcriptomic analysis of human lung epithelial cells (BEAS-2B) expressing active mutant AKT1 (AKT1-E17K), active mutant PIK3CA (PIK3CA-E545K) or that are silenced for PTEN. We found that, altogether, aberrant PI3K/AKT signalling in lung epithelial cells regulated the expression of 1,960/20,436 genes (9%), though only 30 differentially expressed genes (DEGs) (15 up-regulated, 12 down-regulated and 3 discordant) out of 20,436 that were common among BEAS-AKT1-E17K, BEAS-PIK3CA-E545K and BEAS-shPTEN cells (0.1%). Conversely, DEGs specific for mutant AKT1 were 133 (85 up-regulated; 48 down-regulated), DEGs specific for mutant PIK3CA were 502 (280 up-regulated; 222 down-regulated) and DEGs specific for PTEN loss were 1549 (799 up-regulated, 750 down-regulated). The results obtained from array analysis were confirmed by quantitative RT-PCR on selected up- and down-regulated genes (n = 10). Treatment of BEAS-C cells and the corresponding derivatives with pharmacological inhibitors of AKT (MK2206) or PI3K (LY294002) further validated the significance of our findings. Moreover, mRNA expression of selected DEGs (SGK1, IGFBP3, PEG10, GDF15, PTGES, S100P, respectively) correlated with the activation status of the PI3K/AKT pathway assessed by S473 phosphorylation in NSCLC cell lines (n = 6). Finally, we made use of Ingenuity Pathway Analysis (IPA) to investigate the relevant Bio

Concepts for dose determination in flat-detector CT

NASA Astrophysics Data System (ADS)

Kyriakou, Yiannis; Deak, Paul; Langner, Oliver; Kalender, Willi A.

2008-07-01

Flat-detector computed tomography (FD-CT) scanners provide large irradiation fields of typically 200 mm in the cranio-caudal direction. In consequence, dose assessment according to the current definition of the computed tomography dose index CTDIL=100 mm, where L is the integration length, would demand larger ionization chambers and phantoms which do not appear practical. We investigated the usefulness of the CTDI concept and practical dosimetry approaches for FD-CT by measurements and Monte Carlo (MC) simulations. An MC simulation tool (ImpactMC, VAMP GmbH, Erlangen, Germany) was used to assess the dose characteristics and was calibrated with measurements of air kerma. For validation purposes measurements were performed on an Axiom Artis C-arm system (Siemens Medical Solutions, Forchheim, Germany) equipped with a flat detector of 40 cm × 30 cm. The dose was assessed for 70 kV and 125 kV in cylindrical PMMA phantoms of 160 mm and 320 mm diameter with a varying phantom length from 150 to 900 mm. MC simulation results were compared to the values obtained with a calibrated ionization chambers of 100 mm and 250 mm length and to thermoluminesence (TLD) dose profiles. The MCs simulations were used to calculate the efficiency of the CTDIL determination with respect to the desired CTDI∞. Both the MC simulation results and the dose distributions obtained by MC simulation were in very good agreement with the CTDI measurements and with the reference TLD profiles, respectively, to within 5%. Standard CTDI phantoms which have a z-extent of 150 mm underestimate the dose at the center by up to 55%, whereas a z-extent of >=600 mm appears to be sufficient for FD-CT; the baseline value of the respective profile was within 1% to the reference baseline. As expected, the measurements with ionization chambers of 100 mm and 250 mm offer a limited accuracy, whereas an increased integration length of >=600 mm appeared to be necessary to approximate CTDI∞ in within 1%. MC simulations

Identification and Targeting of Upstream Tyrosine Kinases Mediating PI3 Kinase Activation in PTEN Deficient Prostate Cancer

DTIC Science & Technology

2010-06-01

tyrosine phosphorylated proteins, but they were not recognized by an anti-pYxxM motif antibody and were not found in PTEN deficient PC3 PCa cells. LC/MS...p85 binding motif antibody (pYxxM). failed to detect Therefore, we next focused on identification of p85 associated proteins using liquid...LC/MS/MS analysis of the p85 immunoprecipitates using a more sensitive Orbitrap XL mass spectrometer, we also detected GAB1 (Table 1). However, we

Comparison of cell cycle progression score with two immunohistochemical markers (PTEN and Ki-67) for predicting outcome in prostate cancer after radical prostatectomy.

PubMed

Léon, Priscilla; Cancel-Tassin, Geraldine; Drouin, Sara; Audouin, Marie; Varinot, Justine; Comperat, Eva; Cathelineau, Xavier; Rozet, François; Vaessens, Christophe; Stone, Steven; Reid, Julia; Sangale, Zaina; Korman, Patrick; Rouprêt, Morgan; Fromond-Hankard, Gaelle; Cussenot, Olivier

2018-04-20

Previous studies of the cell cycle progression (CCP) score in surgical specimens of prostate cancer (PCa) in patients treated by radical prostatectomy (RP) demonstrated significant association with time to biochemical recurrence (BCR). In this study, we compared the ability of the CCP score and the expression of PTEN or Ki-67 to predict BCR in a cohort of patients treated by RP. Finally, we constructed the best predictive model for BCR, incorporating biomarkers and relevant clinical variables. The study population consisted of 652 PCa patients enrolled in a retrospective cohort and who had RP surgery in French urological centers from 2000 to 2007. Among the 652 patients with CCP scores and complete clinical data, BCR events occurred in 41%, and the median time from surgery to the last follow-up among BCR-free patients was 72 months. In univariate Cox analysis, the continuous CCP score and positive Ki-67 predicted recurrence with a HR of 1.44 (95% CI 1.17-1.75; p = 5.3 × 10 -4 ) and 1.89 (95% CI 1.38-2.57; p = 1.6 × 10 -4 ), respectively. In contrast, PTEN expression was not associated with BCR risk. Of the three biomarkers, only the CCP score remained significantly associated in a multivariable Cox model (p = 0.026). The best model incorporated CAPRA-S and CCP scores as predictors, with HRs of 1.32 and 1.24, respectively. The CCP score was superior to the two IHC markers (PTEN and Ki-67) for predicting outcome in PCa after RP.

TU-D-209-02: A Backscatter Point Spread Function for Entrance Skin Dose Determination

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vijayan, S; Xiong, Z; Shankar, A

Purpose: To determine the distribution of backscattered radiation to the skin resulting from a non-uniform distribution of primary radiation through convolution with a backscatter point spread function (PSF). Methods: A backscatter PSF is determined using Monte Carlo simulation of a 1 mm primary beam incident on a 30 × 30 cm × 20 cm thick PMMA phantom using EGSnrc software. A primary profile is similarly obtained without the phantom and the difference from the total provides the backscatter profile. This scatter PSF characterizes the backscatter spread for a “point” primary interaction and can be convolved with the entrance primary dosemore » distribution to obtain the total entrance skin dose. The backscatter PSF was integrated into the skin dose tracking system (DTS), a graphical utility for displaying the color-coded skin dose distribution on a 3D graphic of the patient during interventional fluoroscopic procedures. The backscatter convolution method was validated for the non-uniform beam resulting from the use of an ROI attenuator. The ROI attenuator is a copper sheet with about 20% primary transmission (0.7 mm thick) containing a circular aperture; this attenuator is placed in the beam to reduce dose in the periphery while maintaining full dose in the region of interest. The DTS calculated primary plus backscatter distribution is compared to that measured with GafChromic film and that calculated using EGSnrc Monte-Carlo software. Results: The PSF convolution method used in the DTS software was able to account for the spread of backscatter from the ROI region to the region under the attenuator. The skin dose distribution determined using DTS with the ROI attenuator was in good agreement with the distributions measured with Gafchromic film and determined by Monte Carlo simulation Conclusion: The PSF convolution technique provides an accurate alternative for entrance skin dose determination with non-uniform primary x-ray beams. Partial support from NIH

Is patient size important in dose determination and optimization in cardiology?

NASA Astrophysics Data System (ADS)

Reay, J.; Chapple, C. L.; Kotre, C. J.

2003-12-01

Patient dose determination and optimization have become more topical in recent years with the implementation of the Medical Exposures Directive into national legislation, the Ionising Radiation (Medical Exposure) Regulations. This legislation incorporates a requirement for new equipment to provide a means of displaying a measure of patient exposure and introduces the concept of diagnostic reference levels. It is normally assumed that patient dose is governed largely by patient size; however, in cardiology, where procedures are often very complex, the significance of patient size is less well understood. This study considers over 9000 cardiology procedures, undertaken throughout the north of England, and investigates the relationship between patient size and dose. It uses simple linear regression to calculate both correlation coefficients and significance levels for data sorted by both room and individual clinician for the four most common examinations, left ventrical and/or coronary angiography, single vessel stent insertion and single vessel angioplasty. This paper concludes that the correlation between patient size and dose is weak for the procedures considered. It also illustrates the use of an existing method for removing the effect of patient size from dose survey data. This allows typical doses and, therefore, reference levels to be defined for the purposes of dose optimization.

Reciprocal feedback regulation of PI3K and androgen receptor signaling in PTEN-deficient prostate cancer

PubMed Central

Carver, Brett S; Chapinski, Caren; Wongvipat, John; Hieronymus, Haley; Chen, Yu; Chandarlapaty, Sarat; Arora, Vivek K; Le, Carl; Koutcher, Jason; Scher, Howard; Scardino, Peter T; Rosen, Neal; Sawyers, Charles L

2011-01-01

Summary Prostate cancer is characterized by its dependence on androgen receptor and frequent activation of PI3K signaling. We find that AR transcriptional output is decreased in human and murine tumors with PTEN deletion and that PI3K pathway inhibition activates AR signaling by relieving feedback inhibition of HER kinases. Similarly, AR inhibition activates AKT signaling by reducing levels of the AKT phosphatase PHLPP. Thus, these two oncogenic pathways cross-regulate each other by reciprocal feedback. Inhibition of one activates the other, thereby maintaining tumor cell survival. However, combined pharmacologic inhibition of PI3K and AR signaling caused near complete prostate cancer regressions in a Pten-deficient murine prostate cancer model and in human prostate cancer xenografts, indicating that both pathways coordinately support survival. Significance The two most frequently activated signaling pathways in prostate cancer are driven by AR and PI3K. Inhibitors of the PI3K pathway are in early clinical trials and AR inhibitors confer clinical responses in most patients. However, these inhibitors rarely induce tumor regression in preclinical models. Here we show that these pathways regulate each other by reciprocal negative feedback, such that inhibition of one activates the other. Therefore, tumor cells can adapt and survive when either single pathway is inhibited pharmacologically. Our demonstration of profound tumor regressions with combined pathway inhibition in preclinical prostate tumor models provides rationale for combination therapy in patients. PMID:21575859

Slow Disease Progression in a C57BL/6 Pten-Deficient Mouse Model of Prostate Cancer

PubMed Central

Svensson, Robert U.; Haverkamp, Jessica M.; Thedens, Daniel R.; Cohen, Michael B.; Ratliff, Timothy L.; Henry, Michael D.

2011-01-01

Prostate-specific deletion of Pten in mice has been reported to recapitulate histological progression of human prostate cancer. To improve on this model, we introduced the conditional ROSA26 luciferase reporter allele to monitor prostate cancer progression via bioluminescence imaging and extensively backcrossed mice onto the albino C57BL/6 genetic background to address variability in tumor kinetics and to enhance imaging sensitivity. Bioluminescence signal increased rapidly in Ptenp−/− mice from 3 to 11 weeks, but was much slower from 11 to 52 weeks. Changes in bioluminescence signal were correlated with epithelial proliferation. Magnetic resonance imaging revealed progressive increases in prostate volume, which were attributed to excessive fluid retention in the anterior prostate and to expansion of the stroma. Development of invasive prostate cancer in 52-week-old Ptenp−/− mice was rare, indicating that disease progression was slowed relative to that in previous reports. Tumors in these mice exhibited a spontaneous inflammatory phenotype and were rapidly infiltrated by myeloid-derived suppressor cells. Although Ptenp−/− tumors responded to androgen withdrawal, they failed to exhibit relapsed growth for up to 1 year. Taken together, these data identify a mild prostate cancer phenotype in C57BL/6 prostate-specific Pten-deficient mice, reflecting effects of the C57BL/6 genetic background on cancer progression. This model provides a platform for noninvasive assessment of how genetic and environmental risk factors may affect disease progression. PMID:21703427

Mutations and Deregulation of Ras/Raf/MEK/ERK and PI3K/PTEN/Akt/mTOR Cascades Which Alter Therapy Response

PubMed Central

McCubrey, James A.; Steelman, Linda S.; Chappell, William H.; Abrams, Stephen L.; Montalto, Giuseppe; Cervello, Melchiorre; Nicoletti, Ferdinando; Fagone, Paolo; Malaponte, Grazia; Mazzarino, Maria C.; Candido, Saverio; Libra, Massimo; Bäsecke, Jörg; Mijatovic, Sanja; Maksimovic-Ivanic, Danijela; Milella, Michele; Tafuri, Agostino; Cocco, Lucio; Evangelisti, Camilla; Chiarini, Francesca; Martelli, Alberto M.

2012-01-01

The Ras/Raf/MEK/ERK and PI3K/PTEN/Akt/mTOR cascades are often activated by genetic alterations in upstream signaling molecules such as receptor tyrosine kinases (RTK). Certain components of these pathways, RAS, NF1, BRAF, MEK1, DUSP5, PP2A, PIK3CA, PIK3R1, PIK3R4, PIK3R5, IRS4, AKT, NFKB1, MTOR, PTEN, TSC1, and TSC2 may also be activated/inactivated by mutations or epigenetic silencing. Upstream mutations in one signaling pathway or even in downstream components of the same pathway can alter the sensitivity of the cells to certain small molecule inhibitors. These pathways have profound effects on proliferative, apoptotic and differentiation pathways. Dysregulation of components of these cascades can contribute to: resistance to other pathway inhibitors, chemotherapeutic drug resistance, premature aging as well as other diseases. This review will first describe these pathways and discuss how genetic mutations and epigenetic alterations can result in resistance to various inhibitors. PMID:23006971

Analysis of Potassium in Bricks--Determining the Dose Rate from {sup 40}K for Thermoluminescence Dating

DOE Office of Scientific and Technical Information (OSTI.GOV)

Musilek, Ladislav; Polach, Tomas; Trojek, Tomas

2008-08-07

Thermoluminescence (TL) dating is based on accumulating the natural radiation dose in the material of a dated artefact (brick, pottery, etc.), and comparing the dose accumulated during the lifetime of the object with the dose rate within the sample collected for TL measurement. Determining the dose rate from natural radionuclides in materials is one of the most important and most difficult parts of the technique. The most important radionuclides present are usually nuclides of the uranium and thorium decay series and {sup 40}K. An analysis of the total potassium concentration enables us to determine the {sup 40}K content effectively, andmore » from this it is possible to calculate the dose rate originating from this radiation source. X-ray fluorescence (XRF) analysis can be used to determine the potassium concentration in bricks rapidly and efficiently. The procedure for analysing potassium, examples of results of dose rate calculation and possible sources of error are described here.« less

Determination of spatial dose distribution in UCC treatments with LDR brachytherapy using Monte Carlo methods.

PubMed

Benites-Rengifo, Jorge Luis; Vega-Carrillo, Hector Rene

2018-05-19

Using Monte Carlos methods, with the MCNP5 code, a gynecological phantom and a vaginal cylinder were modeled. The spatial distribution of absorbed dose rates in Uterine Cervical Cancer treatment through low dose rate brachytherapy was determined. A liquid water gynecology computational phantom, including a vaginal cylinder applicator made of Lucite, was designed. The applicator has a linear array of four radioactive sources of Cesium 137. Around the vaginal cylinder, 13 water spherical cells of 0.5 cm-diameter were modeled to calculate absorbed dose emulating the procedure made by the treatment planning system. The gamma-ray fluence distribution was estimated, as well as the absorbed doses resulting approximately symmetrical for cells located at upper and lower of vaginal cylinder. Obtained results allow the use of the radioactive decay law to determine dose rate for Uterine Cervical Cancer using low dose rate brachytherapy. Copyright © 2018 Elsevier Ltd. All rights reserved.

Oxidative Inactivation of the Lipid Phosphatase Phosphatase and Tensin Homolog on Chromosome Ten (PTEN) as a Novel Mechanism of Acquired Long QT Syndrome*

PubMed Central

Wan, Xiaoping; Dennis, Adrienne T.; Obejero-Paz, Carlos; Overholt, Jeffrey L.; Heredia-Moya, Jorge; Kirk, Kenneth L.; Ficker, Eckhard

2011-01-01

The most common cause of cardiac side effects of pharmaco-therapy is acquired long QT syndrome, which is characterized by abnormal cardiac repolarization and most often caused by direct blockade of the cardiac potassium channel human ether a-go-go-related gene (hERG). However, little is known about therapeutic compounds that target ion channels other than hERG. We have discovered that arsenic trioxide (As2O3), a very potent antineoplastic compound for the treatment of acute promyelocytic leukemia, is proarrhythmic via two separate mechanisms: a well characterized inhibition of hERG/IKr trafficking and a poorly understood increase of cardiac calcium currents. We have analyzed the latter mechanism in the present study using biochemical and electrophysiological methods. We find that oxidative inactivation of the lipid phosphatase PTEN by As2O3 enhances cardiac calcium currents in the therapeutic concentration range via a PI3Kα-dependent increase in phosphatidylinositol 3,4,5-triphosphate (PIP3) production. In guinea pig ventricular myocytes, even a modest reduction in PTEN activity is sufficient to increase cellular PIP3 levels. Under control conditions, PIP3 levels are kept low by PTEN and do not affect calcium current amplitudes. Based on pharmacological experiments and intracellular infusion of PIP3, we propose that in guinea pig ventricular myocytes, PIP3 regulates calcium currents independently of the protein kinase Akt along a pathway that includes a secondary oxidation-sensitive target. Overall, our report describes a novel form of acquired long QT syndrome where the target modified by As2O3 is an intracellular signaling cascade. PMID:21097842

Validation of a MOSFET dosemeter system for determining the absorbed and effective radiation doses in diagnostic radiology.

PubMed

Manninen, A-L; Kotiaho, A; Nikkinen, J; Nieminen, M T

2015-04-01

This study aimed to validate a MOSFET dosemeter system for determining absorbed and effective doses (EDs) in the dose and energy range used in diagnostic radiology. Energy dependence, dose linearity and repeatability of the dosemeter were examined. The absorbed doses (ADs) were compared at anterior-posterior projection and the EDs were determined at posterior-anterior, anterior-posterior and lateral projections of thoracic imaging using an anthropomorphic phantom. The radiation exposures were made using digital radiography systems. This study revealed that the MOSFET system with high sensitivity bias supply set-up is sufficiently accurate for AD and ED determination. The dosemeter is recommended to be calibrated for energies <60 and >80 kVp. The entrance skin dose level should be at least 5 mGy to minimise the deviation of the individual dosemeter dose. For ED determination, dosemeters should be implanted perpendicular to the surface of the phantom to prevent the angular dependence error. © The Author 2014. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Identification and Targeting of Upstream Tyrosine Kinases Mediating PI3 Kinase Activation in PTEN Deficient Prostate Cancer

DTIC Science & Technology

2011-06-01

tyrosine phosphorylated proteins, but they were not recognized by an anti-pYxxM motif antibody and were not found in PTEN deficient PC3 PCa cells. LC/MS/MS...immunoblotted the p85 immunoprecipitates with a pYxxM motif specific antibody . This antibody weakly detected several discrete p85 associated proteins...anti-pYxxM antibody after EGF or heregulin-1 stimulation, with the band after heregulin- 1 being consistent with ErbB3 (which contains 6 pYxxM motifs

Radon Dose Determination for Cave Guides in Czech Republic

NASA Astrophysics Data System (ADS)

Thinova, Lenka; Rovenska, Katerina

2008-08-01

According to recommended approach there are six (from total of twelve) open-to-public caves in Czech Republic, reaching near to an effective lung-dose of 6mSv/year. A conservative approach for estimating the potential effective lung-dose in caves (or underground) is based on two season's measurements, using solid state alpha track detector (Kodak in plastic diffusion chamber). The obtained dataset is converted into an annual effective dose, in agreement with the ICRP65 recommendation, using the "cave factor" 1.5. The value of "cave factor" which depends on the spectrum of aerosol particles, or on the proportional representation of the unattached/attached ratio (6.5 : 93.5 for residential places, 13.6 : 86.4 for caves due to lower concentration of free aerosols) and on the equilibrium factor. Thus conversion factor is 1.5 times higher in comparison with ICRP 65. Is this correct? Because a more precisely determined dose value would have a significant impact on radon remedies, or on restricting the time workers stay underground, a series of measurement was initiated in 2003 with the aim to specify input data, computation and errors in effective dose assessment in each one of the evaluated caves separately. The enhancement of personal dosimetry for underground work places includes a study of the given questions, from the following points of view in each cave: continual radon measurement; regular measurements of radon and its daughters to estimate the equilibrium factor and the presence of free 218Po; regular indoor air flow measurements to study the location of the radon supply and its transfer among individual areas of the cave; natural radioactive element content evaluation in subsoil and in water inside/outside, a study of the radon sources in the cave; determination of the free fraction from continual unattached and attached fraction measurement (grid and filter); thoron measurement. Air flow measurements provide very interesting information about the origin of

Radon Dose Determination for Cave Guides in Czech Republic

DOE Office of Scientific and Technical Information (OSTI.GOV)

Thinova, Lenka; Rovenska, Katerina

2008-08-07

According to recommended approach there are six (from total of twelve) open-to-public caves in Czech Republic, reaching near to an effective lung-dose of 6mSv/year. A conservative approach for estimating the potential effective lung-dose in caves (or underground) is based on two season's measurements, using solid state alpha track detector (Kodak in plastic diffusion chamber). The obtained dataset is converted into an annual effective dose, in agreement with the ICRP65 recommendation, using the 'cave factor' 1.5. The value of 'cave factor' which depends on the spectrum of aerosol particles, or on the proportional representation of the unattached/attached ratio (6.5 : 93.5more » for residential places, 13.6 : 86.4 for caves due to lower concentration of free aerosols) and on the equilibrium factor. Thus conversion factor is 1.5 times higher in comparison with ICRP 65. Is this correct? Because a more precisely determined dose value would have a significant impact on radon remedies, or on restricting the time workers stay underground, a series of measurement was initiated in 2003 with the aim to specify input data, computation and errors in effective dose assessment in each one of the evaluated caves separately. The enhancement of personal dosimetry for underground work places includes a study of the given questions, from the following points of view in each cave: continual radon measurement; regular measurements of radon and its daughters to estimate the equilibrium factor and the presence of free {sup 218}Po; regular indoor air flow measurements to study the location of the radon supply and its transfer among individual areas of the cave; natural radioactive element content evaluation in subsoil and in water inside/outside, a study of the radon sources in the cave; determination of the free fraction from continual unattached and attached fraction measurement (grid and filter); thoron measurement. Air flow measurements provide very interesting information about the

Method to determine the position-dependant metal correction factor for dose-rate equivalent laser testing of semiconductor devices

DOEpatents

Horn, Kevin M.

2013-07-09

A method reconstructs the charge collection from regions beneath opaque metallization of a semiconductor device, as determined from focused laser charge collection response images, and thereby derives a dose-rate dependent correction factor for subsequent broad-area, dose-rate equivalent, laser measurements. The position- and dose-rate dependencies of the charge-collection magnitude of the device are determined empirically and can be combined with a digital reconstruction methodology to derive an accurate metal-correction factor that permits subsequent absolute dose-rate response measurements to be derived from laser measurements alone. Broad-area laser dose-rate testing can thereby be used to accurately determine the peak transient current, dose-rate response of semiconductor devices to penetrating electron, gamma- and x-ray irradiation.

Determination of the efficiency of commercially available dose calibrators for beta-emitters.

PubMed

Valley, Jean-François; Bulling, Shelley; Leresche, Michel; Wastiel, Claude

2003-03-01

The goals of this investigation are to determine whether commercially available dose calibrators can be used to measure the activity of beta-emitting radionuclides used in pain palliation and to establish whether manufacturer-supplied calibration factors are appropriate for this purpose. Six types of commercially available dose calibrators were studied. Dose calibrator response was controlled for 5 gamma-emitters used for calibration or typically encountered in routine use. For the 4 most commonly used beta-emitters ((32)P, (90)Sr, (90)Y, and (169)Er) dose calibrator efficiency was determined in the syringe geometry used for clinical applications. Efficiency of the calibrators was also measured for (153)Sm and (186)Re, 2 beta-emitters with significant gamma-contributions. Source activities were traceable to national standards. All calibrators measured gamma-emitters with a precision of +/-10%, in compliance with Swiss regulatory requirements. For beta-emitters, dose calibrator intrinsic efficiency depends strongly on the maximal energy of the beta-spectrum and is notably low for (169)Er. Manufacturer-supplied calibration factors give accurate results for beta-emitters with maximal beta-energy in the middle-energy range (1 MeV) but are not appropriate for use with low-energy ((169)Er) or high-energy ((90)Y) beta-emitters. beta-emitters with significant gamma-contributions behave like gamma-emitters. Commercially available dose calibrators have an intrinsic efficiency that is sufficient for the measurement of beta-emitters, including beta-emitters with a low maximum beta-energy. Manufacturer-supplied calibration factors are reliable for gamma-emitters and beta-emitters in the middle-energy range. For low- and high-energy beta-emitters, the use of manufacturer-supplied calibration factors introduces significant measurement inaccuracy.

Determination of the uncertainties in radiation doses from ingestion of strontium-90

NASA Astrophysics Data System (ADS)

Apostoaei, Andrei Iulian

Quantification of the uncertainties in the internal dosimetry is important because it can impact the outcome of dose reconstruction, risk assessment or epidemiological studies. This research focused on determination of the uncertainties in the dose factors from a single ingestion of 90Sr by adults, and analyzed the changes with age and the effect of gender. The uncertainties in the estimated dose factors are a factor of 6 for the bone surface, 5 for the red bone marrow, 2.5 for bladder and stomach, 2.2 for the small intestine, 2.1 for the upper large intestine and 2.7 for the lower large intestine. For the rest of the organs the uncertainty is a factor of 3. Only four parameters of the biokinetic model showed an age-dependency within the adult age group: the fractional transfers of strontium from plasma to cortical and trabecular bone, and the removal rates from the cortical and trabecular bone, respectively. When age-dependent biokinetic parameters were used, the estimated dose-factors are very close to the dose factors obtained using age-independent kinetics (within 40%). Thus, the dose factors based on age-independent parameters should suffice for most practical purposes. The dose factors and the associated uncertainties were also calculated as a function of age-at-exposure and attained age. These age dependent curves can be used for estimating doses from continuous intakes, or doses delivered over a limited portion of time. In addition to the committed dose, an expected dose is also estimated in this work. The expected dose is calculated using the dose rate weighted by the probability of surviving up to the age when the dose-rate is delivered. For exposure at young ages the expected dose and the committed dose are similar, but the committed dose decreases to zero when exposure occurs close to age 70, while the expected dose has elevated values pass age 70. No gender differences were found for bone surface, for red bone marrow, and the large intestine. The doses

Micro RNA responses to chronic or acute exposures to low dose ionizing radiation

PubMed Central

Chaudhry, M. Ahmad; Omaruddin, Romaica A.; Kreger, Bridget; de Toledo, Sonia M.; Azzam, Edouard I.

2014-01-01

Human health risks of exposure to low dose ionizing radiation remain ambiguous and are the subject of intense debate. A wide variety of biological effects are induced after cellular exposure to ionizing radiation, but the underlying molecular mechanism(s) remain to be completely understood. We hypothesized that low dose c-radiation-induced effects are controlled by the modulation of micro RNA (miRNA) that participate in the control of gene expression at the posttranscriptional level and are involved in many cellular processes. We monitored the expression of several miRNA in human cells exposed to acute or chronic low doses of 10 cGy or a moderate dose of 400 cGy of 137Cs γ-rays. Dose, dose rate and time dependent differences in the relative expression of several miRNA were investigated. The expression patterns of many miRNA differed after exposure to either chronic or acute 10 cGy. The expression of miRNA let-7e, a negative regulator of RAS oncogene, and the c-MYC miRNA cluster were upregulated after 10 cGy chronic dose but were downregulated after 3 h of acute 10 cGy. The miR-21 was upregulated in chronic or acute low dose and moderate dose treated cells and its target genes hPDCD4, hPTEN, hSPRY2, and hTPM1 were found to be downregulated. These findings provide evidence that low dose and dose rate c-irradiation dictate the modulation of miRNA, which can result in a differential cellular response than occurs at high doses. This information will contribute to understanding the risks to human health after exposure to low dose radiation. PMID:22367372

Transposon mutagenesis identifies genes that cooperate with mutant Pten in breast cancer progression

PubMed Central

Rangel, Roberto; Lee, Song-Choon; Hon-Kim Ban, Kenneth; Guzman-Rojas, Liliana; Mann, Michael B.; Newberg, Justin Y.; McNoe, Leslie A.; Selvanesan, Luxmanan; Ward, Jerrold M.; Rust, Alistair G.; Chin, Kuan-Yew; Black, Michael A.; Jenkins, Nancy A.; Copeland, Neal G.

2016-01-01

Triple-negative breast cancer (TNBC) has the worst prognosis of any breast cancer subtype. To better understand the genetic forces driving TNBC, we performed a transposon mutagenesis screen in a phosphatase and tensin homolog (Pten) mutant mice and identified 12 candidate trunk drivers and a much larger number of progression genes. Validation studies identified eight TNBC tumor suppressor genes, including the GATA-like transcriptional repressor TRPS1. Down-regulation of TRPS1 in TNBC cells promoted epithelial-to-mesenchymal transition (EMT) by deregulating multiple EMT pathway genes, in addition to increasing the expression of SERPINE1 and SERPINB2 and the subsequent migration, invasion, and metastasis of tumor cells. Transposon mutagenesis has thus provided a better understanding of the genetic forces driving TNBC and discovered genes with potential clinical importance in TNBC. PMID:27849608

Dose determinants in continuous renal replacement therapy.

PubMed

Clark, William R; Turk, Joseph E; Kraus, Michael A; Gao, Dayong

2003-09-01

Increasing attention is being paid to quantifying the dose of dialysis prescribed and delivered to critically ill patients with acute renal failure (ARF). Recent trials in both the intermittent hemodialysis (IHD) and continuous renal replacement therapy (CRRT) realms have suggested that a direct relationship between dose and survival exists for both of these therapies. The purpose of this review, first, is to analyze critically the above-mentioned dose/outcome studies in acute dialysis. Subsequently, the factors influencing dose prescription and delivery are discussed, with the focus on continuous venovenous hemofiltration (CVVH). Specifically, differences between postdilution and predilution CVVH will be highlighted, and the importance of blood flow rate in dose delivery for these therapies will be discussed.

MicroRNA-214 protects against hypoxia/reoxygenation induced cell damage and myocardial ischemia/reperfusion injury via suppression of PTEN and Bim1 expression.

PubMed

Wang, Xiaohui; Ha, Tuanzhu; Hu, Yuanping; Lu, Chen; Liu, Li; Zhang, Xia; Kao, Race; Kalbfleisch, John; Williams, David; Li, Chuanfu

2016-12-27

Myocardial apoptosis plays an important role in myocardial ischemia/reperfusion (I/R) injury. Activation of PI3K/Akt signaling protects the myocardium from I/R injury. This study investigated the role of miR-214 in hypoxia/reoxygenation (H/R)-induced cell damage in vitro and myocardial I/R injury in vivo. H9C2 cardiomyoblasts were transfected with lentivirus expressing miR-214 (LmiR-214) or lentivirus expressing scrambled miR-control (LmiR-control) respectively, to establish cell lines of LmiR-214 and LmiR-control. The cells were subjected to hypoxia for 4 h followed by reoxygenation for 24 h. Transfection of LmiR-214 suppresses PTEN expression, significantly increases the levels of Akt phosphorylation, markedly attenuates LDH release, and enhances the viability of the cells subjected to H/R. In vivo transfection of mouse hearts with LmiR-214 significantly attenuates I/R induced cardiac dysfunction and reduces I/R-induced myocardial infarct size. LmiR-214 transfection significantly attenuates I/R-induced myocardial apoptosis and caspase-3/7 and caspase-8 activity. Increased expression of miR-214 by transfection of LmiR-214 suppresses PTEN expression, increases the levels of phosphorylated Akt, represses Bim1 expression and induces Bad phosphorylation in the myocardium. In addition, in vitro data shows transfection of miR-214 mimics to H9C2 cells suppresses the expression and translocation of Bim1 from cytosol to mitochondria and induces Bad phosphorylation. Our in vitro and in vivo data suggests that miR-214 protects cells from H/R induced damage and attenuates I/R induced myocardial injury. The mechanisms involve activation of PI3K/Akt signaling by targeting PTEN expression, induction of Bad phosphorylation, and suppression of Bim1 expression, resulting in decreases in I/R-induced myocardial apoptosis.

A procedure to determine the planar integral spot dose values of proton pencil beam spots

DOE Office of Scientific and Technical Information (OSTI.GOV)

Anand, Aman; Sahoo, Narayan; Zhu, X. Ronald

2012-02-15

Purpose: Planar integral spot dose (PISD) of proton pencil beam spots (PPBSs) is a required input parameter for beam modeling in some treatment planning systems used in proton therapy clinics. The measurement of PISD by using commercially available large area ionization chambers, like the PTW Bragg peak chamber (BPC), can have large uncertainties due to the size limitation of these chambers. This paper reports the results of our study of a novel method to determine PISD values from the measured lateral dose profiles and peak dose of the PPBS. Methods: The PISDs of 72.5, 89.6, 146.9, 181.1, and 221.8 MeVmore » energy PPBSs were determined by area integration of their planar dose distributions at different depths in water. The lateral relative dose profiles of the PPBSs at selected depths were measured by using small volume ion chambers and were investigated for their angular anisotropies using Kodak XV films. The peak spot dose along the beam's central axis (D{sub 0}) was determined by placing a small volume ion chamber at the center of a broad field created by the superposition of spots at different locations. This method allows eliminating positioning uncertainties and the detector size effect that could occur when measuring it in single PPBS. The PISD was then calculated by integrating the measured lateral relative dose profiles for two different upper limits of integration and then multiplying it with corresponding D{sub 0}. The first limit of integration was set to radius of the BPC, namely 4.08 cm, giving PISD{sub RBPC}. The second limit was set to a value of the radial distance where the profile dose falls below 0.1% of the peak giving the PISD{sub full}. The calculated values of PISD{sub RBPC} obtained from area integration method were compared with the BPC measured values. Long tail dose correction factors (LTDCFs) were determined from the ratio of PISD{sub full}/PISD{sub RBPC} at different depths for PPBSs of different energies. Results: The spot

Histone methyltransferase SETDB1 maintains survival of mouse spermatogonial stem/progenitor cells via PTEN/AKT/FOXO1 pathway.

PubMed

Liu, Tiantian; Chen, Xiaoxu; Li, Tianjiao; Li, Xueliang; Lyu, Yinghua; Fan, Xiaoteng; Zhang, Pengfei; Zeng, Wenxian

2017-10-01

Spermatogonial stem cells (SSCs) possess the capacity of self-renewal and differentiation, which are the basis of spermatogenesis. In maintenance of SSC homeostasis, intrinsic/extrinsic factors and various signaling pathways tightly control the fate of SSCs. Methyltransferase SETDB1 (Set domain, bifurcated 1) catalyzes histone H3 lysine 9 (H3K9) trimethylation and represses gene expression. SETDB1 is required for maintaining the survival of spermatogonial stem cells in mice. However, the underlying molecular mechanism remains unclear. In the present study, we found that Setdb1 regulates PTEN/AKT/FOXO1 pathway to inhibit SSC apoptosis. Co-immunoprecipitation and reporter gene assay revealed that SETDB1 interacted and coordinated with AKT to regulate FOXO1 activity and expression of the downstream target genes Bim and Puma. Among the SETDB1-bound genes, the H3K9me3 levels on the promoter regions of Bim and Pten decreased in Setdb1-KD group; in contrast, H3K9me3 status on promoters of Bax and Puma remained unchanged. Therefore, SETDB1 was responsible for regulating the transcription activity of genes in the apoptotic pathway at least in part through modulating H3K9me3. This study replenishes the research on the epigenetic regulation of SSC survival, and provides a new insight for the future study of epigenetic regulation of spermatogenesis. Copyright © 2017 Elsevier B.V. All rights reserved.

Cellular prostatic acid phosphatase, a PTEN-functional homologue in prostate epithelia, functions as a prostate-specific tumor suppressor

PubMed Central

Muniyan, Sakthivel; Ingersoll, Matthew A.; Batra, Surinder K.; Lin, Ming-Fong

2014-01-01

The inactivation of tumor suppressor genes (TSGs) plays a vital role in the progression of human cancers. Nevertheless, those ubiquitous TSGs have been shown with limited roles in various stages of diverse carcinogenesis. Investigation on identifying unique TSG, especially for early stage of carcinogenesis, is imperative. As such, the search for organ-specific TSGs has emerged as a major strategy in cancer research. Prostate cancer (PCa) has the highest incidence in solid tumors in US males. Cellular prostatic acid phosphatase (cPAcP) is a prostate-specific differentiation antigen. Despite intensive studies over the past several decades on PAcP as a PCa biomarker, the role of cPAcP as a PCa-specific tumor suppressor has only recently been emerged and validated. The mechanism underlying the pivotal role of cPAcP as a prostate-specific TSG is, in part, due to its function as a protein tyrosine phosphatase (PTP) as well as a phosphoinositide phosphatase (PIP), an apparent functional homologue to Phosphatase and tensin homolog (PTEN) in PCa cells. This review is focused on discussing the function of this authentic prostate-specific tumor suppressor and the mechanism behind the loss of cPAcP expression leading to prostate carcinogenesis. We review other phosphatases’ roles as TSGs which regulate oncogenic PI3K signaling in PCa and discuss the functional similarity between cPAcP and PTEN in prostate carcinogenesis. PMID:24747769

TLD extrapolation for skin dose determination in vivo.

PubMed

Kron, T; Butson, M; Hunt, F; Denham, J

1996-11-01

Prediction of skin reactions requires knowledge of the dose at various depths in the human skin. Using thermoluminescence dosimeters of three different thicknesses, the dose can be extrapolated to the surface and interpolated between the different depths. A TLD holder was designed for these TLD extrapolation measurements on patients during treatment which allowed measurements of entrance and exit skin dose with a day to day variability of +/-7% (S.D. of mean reading). In a pilot study on 18 patients undergoing breast irradiation, it was found that the angle of incidence of the radiation beam is the most significant factor influencing skin entrance dose. In most of these measurements the beam exit dose contributed 50% more to the surface dose than the entrance dose.

The miR-21/PTEN/Akt signaling pathway is involved in the anti-tumoral effects of zoledronic acid in human breast cancer cell lines.

PubMed

Fragni, M; Bonini, S A; Bettinsoli, P; Bodei, S; Generali, D; Bottini, A; Spano, P F; Memo, M; Sigala, S

2016-05-01

Preclinical data indicate a direct anti-tumor effect of zoledronic acid (ZA) outside the skeleton, but its molecular mechanism is still not completely clarified. The aim of this study was to investigate the anti-cancer effects of ZA in human breast cancer cell lines, suggesting that they may in part be mediated via the miR-21/PTEN/Akt signaling pathway. The effect of ZA on cell viability was measured by MTT assay, and cell death induction was analyzed using either a double AO/EtBr staining and M30 ELISA assay. A Proteome Profiler Human Apoptosis Array was executed to evaluate the molecular basis of ZA-induced apoptosis. Cell cycle analysis was executed by flow cytometry. The effect of ZA on miR-21 expression was quantified by qRT-PCR, and the amount of PTEN protein and its targets were analyzed by Western blot. ZA inhibited cell growth in a concentration- and time-dependent manner, through the activation of cell death pathways and arrest of cell cycle progression. ZA downregulated the expression of miR-21, resulting in dephosphorilation of Akt and Bad and in a significant increase of p21 and p27 proteins expression. These results were observed also in MDA-MB-231 cells, commonly used as an experimental model of bone metastasis of breast cancer. This study revealed, for the first time, an involvement of the miR-21/PTEN/Akt signaling pathway in the mechanism of ZA anti-cancer actions in breast cancer cells. We would like to underline that this pathway is present both in the hormone responsive BC cell line (MCF-7) as well as in a triple negative cell line (MDA-MB-231). Taken together these results reinforce the use of ZA in clinical practice, suggesting the role of miR-21 as a possible mediator of its therapeutic efficacy.

Integrated β-catenin, BMP, PTEN, and Notch signalling patterns the nephron.

PubMed

Lindström, Nils O; Lawrence, Melanie L; Burn, Sally F; Johansson, Jeanette A; Bakker, Elvira R M; Ridgway, Rachel A; Chang, C-Hong; Karolak, Michele J; Oxburgh, Leif; Headon, Denis J; Sansom, Owen J; Smits, Ron; Davies, Jamie A; Hohenstein, Peter

2015-02-03

The different segments of the nephron and glomerulus in the kidney balance the processes of water homeostasis, solute recovery, blood filtration, and metabolite excretion. When segment function is disrupted, a range of pathological features are presented. Little is known about nephron patterning during embryogenesis. In this study, we demonstrate that the early nephron is patterned by a gradient in β-catenin activity along the axis of the nephron tubule. By modifying β-catenin activity, we force cells within nephrons to differentiate according to the imposed β-catenin activity level, thereby causing spatial shifts in nephron segments. The β-catenin signalling gradient interacts with the BMP pathway which, through PTEN/PI3K/AKT signalling, antagonises β-catenin activity and promotes segment identities associated with low β-catenin activity. β-catenin activity and PI3K signalling also integrate with Notch signalling to control segmentation: modulating β-catenin activity or PI3K rescues segment identities normally lost by inhibition of Notch. Our data therefore identifies a molecular network for nephron patterning.

Rac1-mediated membrane raft localization of PI3K/p110β is required for its activation by GPCRs or PTEN loss

PubMed Central

Cizmecioglu, Onur; Ni, Jing; Xie, Shaozhen; Zhao, Jean J; Roberts, Thomas M

2016-01-01

We aimed to understand how spatial compartmentalization in the plasma membrane might contribute to the functions of the ubiquitous class IA phosphoinositide 3-kinase (PI3K) isoforms, p110α and p110β. We found that p110β localizes to membrane rafts in a Rac1-dependent manner. This localization potentiates Akt activation by G-protein-coupled receptors (GPCRs). Thus genetic targeting of a Rac1 binding-deficient allele of p110β to rafts alleviated the requirement for p110β-Rac1 association for GPCR signaling, cell growth and migration. In contrast, p110α, which does not play a physiological role in GPCR signaling, is found to reside in nonraft regions of the plasma membrane. Raft targeting of p110α allowed its EGFR-mediated activation by GPCRs. Notably, p110β dependent, PTEN null tumor cells critically rely upon raft-associated PI3K activity. Collectively, our findings provide a mechanistic account of how membrane raft localization regulates differential activation of distinct PI3K isoforms and offer insight into why PTEN-deficient cancers depend on p110β. DOI: http://dx.doi.org/10.7554/eLife.17635.001 PMID:27700986

An optimized computational method for determining the beta dose distribution using a multiple-element thermoluminescent dosimeter system.

PubMed

Shen, L; Levine, S H; Catchen, G L

1987-07-01

This paper describes an optimization method for determining the beta dose distribution in tissue, and it describes the associated testing and verification. The method uses electron transport theory and optimization techniques to analyze the responses of a three-element thermoluminescent dosimeter (TLD) system. Specifically, the method determines the effective beta energy distribution incident on the dosimeter system, and thus the system performs as a beta spectrometer. Electron transport theory provides the mathematical model for performing the optimization calculation. In this calculation, parameters are determined that produce calculated doses for each of the chip/absorber components in the three-element TLD system. The resulting optimized parameters describe an effective incident beta distribution. This method can be used to determine the beta dose specifically at 7 mg X cm-2 or at any depth of interest. The doses at 7 mg X cm-2 in tissue determined by this method are compared to those experimentally determined using an extrapolation chamber. For a great variety of pure beta sources having different incident beta energy distributions, good agreement is found. The results are also compared to those produced by a commonly used empirical algorithm. Although the optimization method produces somewhat better results, the advantage of the optimization method is that its performance is not sensitive to the specific method of calibration.

Paeonol protects rat vascular endothelial cells from ox-LDL-induced injury in vitro via downregulating microRNA-21 expression and TNF-α release

PubMed Central

Liu, Ya-rong; Chen, Jun-jun; Dai, Min

2014-01-01

Aim: Paeonol (2′-hydroxy-4′-methoxyacetophenone) from Cortex moutan root is a potential therapeutic agent for atherosclerosis. This study sought to investigate the mechanisms underlying anti-inflammatory effects of paeonol in rat vascular endothelial cells (VECs) in vitro. Methods: VECs were isolated from rat thoracic aortas. The cells were pretreated with paeonol for 24 h, and then stimulated with ox-LDL for another 24 h. The expression of microRNA-21 (miR-21) and PTEN in VECs was analyzed using qRT-PCR. The expression of PTEN protein was detected by Western blotting. TNF-α release by VECs was measured by ELISA. Results: Ox-LDL treatment inhibited VEC growth in dose- and time-dependent manners (the value of IC50 was about 20 mg/L at 24 h). Furthermore, ox-LDL (20 mg/L) significantly increased miR-21 expression and inhibited the expression of PTEN, one of downstream target genes of miR-21 in VECs. In addition, ox-LDL (20 mg/L) significantly increased the release of TNF-α from VECs. Pretreatment with paeonol increased the survival rate of ox-LDL-treated VECs in dose- and time-dependent manners. Moreover, paeonol (120 μmol/L) prevented ox-LDL-induced increases in miR-21 expression and TNF-α release, and ox-LDL-induced inhibition in PTEN expression. A dual-luciferase reporter assay showed that miR-21 bound directly to PTEN's 3′-UTR, thus inhibiting PTEN expression. In ox-LDL treated VECs, transfection with a miR-21 mimic significantly increased miR-21 expression and inhibited PTEN expression, and attenuated the protective effects of paeonol pretreatment, whereas transfection with an miR-21 inhibitor significantly decreased miR-21 expression and increased PTEN expression, thus enhanced the protective effects of paeonol pretreatment. Conclusion: miR-21 is an important target of paeonol for its protective effects against ox-LDL-induced VEC injury, which may play critical roles in development of atherosclerosis. PMID:24562307

ErbB2-positive mammary tumors can escape PI3K-p110α loss through downregulation of the Pten tumor suppressor

PubMed Central

Simond, Alexandra M.; Rao, Trisha; Zuo, Dongmei; Zhao, Jean J.; Muller, William J.

2017-01-01

Breast cancer is the most common cancer among women and 30% will be diagnosed with an ErbB2-positive cancer. Forty percent of ErbB2-positive breast tumors have an activating mutation in p110α, a catalytic subunit of phosphoinositide 3-kinase (PI3K). Clinical and experimental data show that breast tumors treated with a p110α-specific inhibitor often circumvent inhibition and resume growth. To understand this mechanism of resistance, we crossed a p110α conditional (p110αflx/flx) mouse model with mice that overexpresses the ErbB2/Neu-IRES-Cre transgene (NIC) specifically in the mammary epithelium. Although mammary-specific deletion of p110α dramatically delays tumor onset, tumors eventually arise and are dependent on p110β. Through biochemical analyses we find that a proportion of p110α-deficient tumors (23%) display downregulation of the Pten tumor suppressor. We further demonstrate that loss of one allele of PTEN is sufficient to shift isoform dependency from p110α to p110β in vivo. These results provide insight into the molecular mechanism by which ErbB2-positive breast cancer escapes p110α inhibition. PMID:28783168

Determination of dose distributions and parameter sensitivity

DOE Office of Scientific and Technical Information (OSTI.GOV)

Napier, B.A.; Farris, W.T.; Simpson, J.C.

1992-12-01

A series of scoping calculations has been undertaken to evaluate the absolute and relative contribution of different radionuclides and exposure pathways to doses that may have been received by individuals living in the vicinity of the Hanford site. This scoping calculation (Calculation 005) examined the contributions of numerous parameters to the uncertainty distribution of doses calculated for environmental exposures and accumulation in foods. This study builds on the work initiated in the first scoping study of iodine in cow's milk and the third scoping study, which added additional pathways. Addressed in this calculation were the contributions to thyroid dose ofmore » infants from (1) air submersion and groundshine external dose, (2) inhalation, (3) ingestion of soil by humans, (4) ingestion of leafy vegetables, (5) ingestion of other vegetables and fruits, (6) ingestion of meat, (7) ingestion of eggs, and (8) ingestion of cows' milk from Feeding Regime 1 as described in Calculation 001.« less

Discrete roles and bifurcation of PTEN signaling and mTORC1-mediated anabolic metabolism underlie IL-7–driven B lymphopoiesis

PubMed Central

Zeng, Hu; Yu, Mei; Tan, Haiyan; Li, Yuxin; Su, Wei; Shi, Hao; Dhungana, Yogesh; Guy, Cliff; Neale, Geoffrey; Cloer, Caryn; Peng, Junmin; Wang, Demin; Chi, Hongbo

2018-01-01

Interleukin-7 (IL-7) drives early B lymphopoiesis, but the underlying molecular circuits remain poorly understood, especially how Stat5 (signal transducer and activator of transcription 5)–dependent and Stat5-independent pathways contribute to this process. Combining transcriptome and proteome analyses and mouse genetic models, we show that IL-7 promotes anabolic metabolism and biosynthetic programs in pro-B cells. IL-7–mediated activation of mTORC1 (mechanistic target of rapamycin complex 1) supported cell proliferation and metabolism in a Stat5-independent, Myc-dependent manner but was largely dispensable for cell survival or Rag1 and Rag2 gene expression. mTORC1 was also required for Myc-driven lymphomagenesis. PI3K (phosphatidylinositol 3-kinase) and mTORC1 had discrete effects on Stat5 signaling and independently controlled B cell development. PI3K was actively suppressed by PTEN (phosphatase and tensin homolog) in pro-B cells to ensure proper IL-7R expression, Stat5 activation, heavy chain rearrangement, and cell survival, suggesting the unexpected bifurcation of the classical PI3K-mTOR signaling. Together, our integrative analyses establish IL-7R–mTORC1–Myc and PTEN-mediated PI3K suppression as discrete signaling axes driving B cell development, with differential effects on IL-7R–Stat5 signaling. PMID:29399633

Plasma Membrane Permeabilization by 60- and 600-ns Electric Pulses Is Determined by the Absorbed Dose

PubMed Central

Ibey, Bennett L.; Xiao, Shu; Schoenbach, Karl H.; Murphy, Michael R.; Pakhomov, Andrei G.

2008-01-01

We explored how the effect of plasma membrane permeabilization by nanosecond-duration electric pulses (nsEP) depends on the physical characteristics of exposure. The resting membrane resistance (Rm) and membrane potential (MP) were measured in cultured GH3 and CHO cells by conventional whole-cell patch-clamp technique. Intact cells were exposed to a single nsEP (60 or 600 ns duration, 0-22 kV/cm), followed by patch-clamp measurements after a 2-3 min delay. Consistent with earlier findings, nsEP caused long-lasting Rm decrease, accompanied by the loss of MP. The threshold for these effects was about 6 kV/cm for 60 ns pulses, and about 1 kV/cm for 600 ns pulses. Further analysis established that it was neither pulse duration nor the E-field amplitude per se, but the absorbed dose that determined the magnitude of the biological effect. In other words, exposure to nsEP at either pulse duration caused equal effects if the absorbed doses were equal. The threshold absorbed dose to produce plasma membrane effects in either GH3 or CHO cells at either pulse duration was found to be at or below 10 mJ/g. Despite being determined by the dose, the nsEP effect clearly is not thermal, as the maximum heating at the threshold dose is less than 0.01 °C. The use of the absorbed dose as a universal exposure metric may help to compare and quantify nsEP sensitivity of different cell types and of cells in different physiological conditions. The absorbed dose may also prove to be a more useful metric than the incident E-field in determining safety limits for high peak, lowaverage power EMF emissions. PMID:18839412

WE-E-18A-03: How Accurately Can the Peak Skin Dose in Fluoroscopy Be Determined Using Indirect Dose Metrics?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Jones, A; Pasciak, A

Purpose: Skin dosimetry is important for fluoroscopically-guided interventions, as peak skin doses (PSD) that Result in skin reactions can be reached during these procedures. The purpose of this study was to assess the accuracy of different indirect dose estimates and to determine if PSD can be calculated within ±50% for embolization procedures. Methods: PSD were measured directly using radiochromic film for 41 consecutive embolization procedures. Indirect dose metrics from procedures were collected, including reference air kerma (RAK). Four different estimates of PSD were calculated and compared along with RAK to the measured PSD. The indirect estimates included a standard method,more » use of detailed information from the RDSR, and two simplified calculation methods. Indirect dosimetry was compared with direct measurements, including an analysis of uncertainty associated with film dosimetry. Factors affecting the accuracy of the indirect estimates were examined. Results: PSD calculated with the standard calculation method were within ±50% for all 41 procedures. This was also true for a simplified method using a single source-to-patient distance (SPD) for all calculations. RAK was within ±50% for all but one procedure. Cases for which RAK or calculated PSD exhibited large differences from the measured PSD were analyzed, and two causative factors were identified: ‘extreme’ SPD and large contributions to RAK from rotational angiography or runs acquired at large gantry angles. When calculated uncertainty limits [−12.8%, 10%] were applied to directly measured PSD, most indirect PSD estimates remained within ±50% of the measured PSD. Conclusions: Using indirect dose metrics, PSD can be determined within ±50% for embolization procedures, and usually to within ±35%. RAK can be used without modification to set notification limits and substantial radiation dose levels. These results can be extended to similar procedures, including vascular and interventional

Preliminary investigations on the determination of three-dimensional dose distributions using scintillator blocks and optical tomography

DOE Office of Scientific and Technical Information (OSTI.GOV)

Kroll, Florian; Karsch, Leonhard; Pawelke, Jörg

2013-08-15

Purpose: Clinical QA in teletherapy as well as the characterization of experimental radiation sources for future medical applications requires effective methods for measuring three-dimensional (3D) dose distributions generated in a water-equivalent medium. Current dosimeters based on ionization chambers, diodes, thermoluminescence detectors, radiochromic films, or polymer gels exhibit various drawbacks: High quality 3D dose determination is either very sophisticated and expensive or requires high amounts of effort and time for the preparation or read out. New detectors based on scintillator blocks in combination with optical tomography are studied, since they have the potential to facilitate the desired cost-effective, transportable, and long-termmore » stable dosimetry system that is able to determine 3D dose distributions with high spatial resolution in a short time.Methods: A portable detector prototype was set up based on a plastic scintillator block and four digital cameras. During irradiation the scintillator emits light, which is detected by the fixed cameras. The light distribution is then reconstructed by optical tomography, using maximum-likelihood expectation maximization. The result of the reconstruction approximates the 3D dose distribution. First performance tests of the prototype using laser light were carried out. Irradiation experiments were performed with ionizing radiation, i.e., bremsstrahlung (6 to 21 MV), electrons (6 to 21 MeV), and protons (68 MeV), provided by clinical and research accelerators.Results: Laser experiments show that the current imaging properties differ from the design specifications: The imaging scale of the optical systems is position dependent, ranging from 0.185 mm/pixel to 0.225 mm/pixel. Nevertheless, the developed dosimetry method is proven to be functional for electron and proton beams. Induced radiation doses of 50 mGy or more made 3D dose reconstructions possible. Taking the imaging properties into account

Preliminary investigations on the determination of three-dimensional dose distributions using scintillator blocks and optical tomography.

PubMed

Kroll, Florian; Pawelke, Jörg; Karsch, Leonhard

2013-08-01

Clinical QA in teletherapy as well as the characterization of experimental radiation sources for future medical applications requires effective methods for measuring three-dimensional (3D) dose distributions generated in a water-equivalent medium. Current dosimeters based on ionization chambers, diodes, thermoluminescence detectors, radiochromic films, or polymer gels exhibit various drawbacks: High quality 3D dose determination is either very sophisticated and expensive or requires high amounts of effort and time for the preparation or read out. New detectors based on scintillator blocks in combination with optical tomography are studied, since they have the potential to facilitate the desired cost-effective, transportable, and long-term stable dosimetry system that is able to determine 3D dose distributions with high spatial resolution in a short time. A portable detector prototype was set up based on a plastic scintillator block and four digital cameras. During irradiation the scintillator emits light, which is detected by the fixed cameras. The light distribution is then reconstructed by optical tomography, using maximum-likelihood expectation maximization. The result of the reconstruction approximates the 3D dose distribution. First performance tests of the prototype using laser light were carried out. Irradiation experiments were performed with ionizing radiation, i.e., bremsstrahlung (6 to 21 MV), electrons (6 to 21 MeV), and protons (68 MeV), provided by clinical and research accelerators. Laser experiments show that the current imaging properties differ from the design specifications: The imaging scale of the optical systems is position dependent, ranging from 0.185 mm/pixel to 0.225 mm/pixel. Nevertheless, the developed dosimetry method is proven to be functional for electron and proton beams. Induced radiation doses of 50 mGy or more made 3D dose reconstructions possible. Taking the imaging properties into account, determined dose profiles are in