scholarly journals Intestinal epithelial-specific PTEN inactivation results in tumor formation

2011 ◽  
Vol 301 (5) ◽  
pp. G856-G864 ◽  
Author(s):  
Do-Sun Byun ◽  
Naseem Ahmed ◽  
Shannon Nasser ◽  
Joongho Shin ◽  
Sheren Al-Obaidi ◽  
...  
Keyword(s):  
Cell Fate ◽  
Intestinal Epithelium ◽  
Suppressor Gene ◽  
Major Effect ◽  
Tumor Formation ◽  
Negative Regulator ◽  
Intestinal Epithelial ◽  
Phosphatase And Tensin Homolog ◽  
Tensin Homolog ◽  
Pten Deletion

Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is a negative regulator of phosphatidylinositol 3-kinase (PI3K) signaling that is frequently inactivated in colorectal cancer through mutation, loss of heterozygosity, or epigenetic mechanisms. The aim of this study was to determine the effect of intestinal-specific PTEN inactivation on intestinal epithelial homeostasis and tumorigenesis. PTEN was deleted specifically in the intestinal epithelium, by crossing PTEN Lox/ Lox mice with villin Cre mice. PTEN was robustly expressed in the intestinal epithelium and maximally in the differentiated cell compartment. Targeted inactivation of PTEN in the intestinal epithelium of PTEN Lox/ Lox/villin Cre mice was confirmed by genotyping, immunohistochemistry, and qPCR. While intestinal-specific PTEN deletion did not have a major effect on cell fate determination or proliferation in the small intestine, it did increase phosphorylated (p) protein kinase B (AKT) expression in the intestinal epithelium, and 19% of animals developed small intestinal adenomas and adenocarcinomas at 12 mo of age. These tumors demonstrated pAKT and nuclear β-catenin staining, indicating simultaneous activation of the PI3K/AKT and Wnt signaling pathways. These findings demonstrate that, while PTEN inactivation alone has a minimal effect on intestinal homeostasis, it can facilitate tumor promotion upon deregulation of β-catenin/TCF signaling, further establishing PTEN as a bona fide tumor suppressor gene in intestinal cancer.

scholarly journals PTEN regulates glioblastoma oncogenesis through chromatin-associated complexes of DAXX and histone H3.3

2017 ◽  
Vol 8 (1) ◽  
Author(s):  
Jorge A. Benitez ◽  
Jianhui Ma ◽  
Matteo D’Antonio ◽  
Antonia Boyer ◽  
Maria Fernanda Camargo ◽  
...  
Keyword(s):  
Suppressor Gene ◽  
Tumour Suppressor Gene ◽  
Tumour Suppressor ◽  
Growth Defect ◽  
Tumour Suppressor Genes ◽  
Phosphatase And Tensin Homolog ◽  
Tensin Homolog ◽  
Pten Deletion ◽  
Therapeutic Opportunity ◽  
Associated Function

Abstract Glioblastoma (GBM) is the most lethal type of human brain cancer, where deletions and mutations in the tumour suppressor gene PTEN (phosphatase and tensin homolog) are frequent events and are associated with therapeutic resistance. Herein, we report a novel chromatin-associated function of PTEN in complex with the histone chaperone DAXX and the histone variant H3.3. We show that PTEN interacts with DAXX and, in turn PTEN directly regulates oncogene expression by modulating DAXX-H3.3 association on the chromatin, independently of PTEN enzymatic activity. Furthermore, DAXX inhibition specifically suppresses tumour growth and improves the survival of orthotopically engrafted mice implanted with human PTEN-deficient glioma samples, associated with global H3.3 genomic distribution changes leading to upregulation of tumour suppressor genes and downregulation of oncogenes. Moreover, DAXX expression anti-correlates with PTEN expression in GBM patient samples. Since loss of chromosome 10 and PTEN are common events in cancer, this synthetic growth defect mediated by DAXX suppression represents a therapeutic opportunity to inhibit tumorigenesis specifically in the context of PTEN deletion.

scholarly journals Redox Regulation of PTEN by Peroxiredoxins

Antioxidants ◽  
2021 ◽  
Vol 10 (2) ◽  
pp. 302
Author(s):  
Thang Nguyen Huu ◽  
Jiyoung Park ◽  
Ying Zhang ◽  
Iha Park ◽  
Hyun Joong Yoon ◽  
...  
Keyword(s):  
Redox Regulation ◽  
Redox Homeostasis ◽  
Direct Interaction ◽  
Suppressor Gene ◽  
Cysteine Residue ◽  
Negative Regulator ◽  
Phosphatase And Tensin Homolog ◽  
Tensin Homolog ◽  
Tumor Suppressive Function ◽  
Phosphatidylinositol 4

Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is known as a tumor suppressor gene that is frequently mutated in numerous human cancers and inherited syndromes. PTEN functions as a negative regulator of PI3K/Akt signaling pathway by dephosphorylating phosphatidylinositol (3, 4, 5)-trisphosphate (PIP3) to phosphatidylinositol (4, 5)-bisphosphate (PIP2), which leads to the inhibition of cell growth, proliferation, cell survival, and protein synthesis. PTEN contains a cysteine residue in the active site that can be oxidized by peroxides, forming an intramolecular disulfide bond between Cys124 and Cys71. Redox regulation of PTEN by reactive oxygen species (ROS) plays a crucial role in cellular signaling. Peroxiredoxins (Prxs) are a superfamily of peroxidase that catalyzes reduction of peroxides and maintains redox homeostasis. Mammalian Prxs have 6 isoforms (I-VI) and can scavenge cellular peroxides. It has been demonstrated that Prx I can preserve and promote the tumor-suppressive function of PTEN by preventing oxidation of PTEN under benign oxidative stress via direct interaction. Also, Prx II-deficient cells increased PTEN oxidation and insulin sensitivity. Furthermore, Prx III has been shown to protect PTEN from oxidation induced by 15s-HpETE and 12s-HpETE, these are potent inflammatory and pro-oxidant mediators. Understanding the tight connection between PTEN and Prxs is important for providing novel therapies. Herein, we summarized recent studies focusing on the relationship of Prxs and the redox regulation of PTEN.

scholarly journals The Role of PTEN in Tumor Angiogenesis

2012 ◽  
Vol 2012 ◽  
pp. 1-11 ◽  
Author(s):  
Stéphane Rodriguez ◽  
Uyen Huynh-Do
Keyword(s):  
Tumor Angiogenesis ◽  
Molecular Mechanisms ◽  
Tumor Formation ◽  
Phosphatase And Tensin Homolog ◽  
Tensin Homolog ◽  
Physiological Processes ◽  
Response To Chemotherapy ◽  
Independent Functions ◽  
Pi3 Kinase Pathway

During the past 20 years, the phosphatase and tensin homolog PTEN has been shown to be involved in major physiological processes, and its mutation or loss is often associated with tumor formation. In addition PTEN regulates angiogenesis not only through its antagonizing effect on the PI3 kinase pathway mainly, but also through some phosphatase-independent functions. In this paper we delineate the role of this powerful tumor suppressor in tumor angiogenesis and dissect the underlying molecular mechanisms. Furthermore, it appears that, in a number of cancers, the PTEN status determines the response to chemotherapy, highlighting the need to monitor PTEN expression and to develop PTEN-targeted therapies.

scholarly journals Modeling PTEN overexpression-induced microcephaly in human brain organoids

2021 ◽  
Vol 14 (1) ◽  
Author(s):  
Navroop Dhaliwal ◽  
Wendy W.Y. Choi ◽  
Julien Muffat ◽  
Yun Li
Keyword(s):  
Human Brain ◽  
Human Genetics ◽  
Negative Regulator ◽  
Akt Inhibitor ◽  
Chromosome 10 ◽  
Phosphatase And Tensin Homolog ◽  
Tensin Homolog ◽  
Pi3k Signaling Pathway ◽  
Brain Organoid ◽  
Phosphoinositide 3 Kinase

AbstractThe phosphatase and tensin homolog (PTEN) protein, encoded by the PTEN gene on chromosome 10, is a negative regulator of the phosphoinositide 3-kinase (PI3K) signaling pathway. Loss of PTEN has been linked to an array of human diseases, including neurodevelopmental disorders such as macrocephaly and autism. However, it remains unknown whether increased dosage of PTEN can lead to human disease. A recent human genetics study identifies chromosome 10 microduplication encompassing PTEN in patients with microcephaly. Here we generated a human brain organoid model of increased PTEN dosage. We showed that mild PTEN overexpression led to reduced neural precursor proliferation, premature neuronal differentiation, and the formation of significantly smaller brain organoids. PTEN overexpression resulted in decreased AKT activation, and treatment of wild-type organoids with an AKT inhibitor recapitulated the reduced brain organoid growth phenotypes. Together, our findings provide functional evidence that PTEN is a dosage-sensitive gene that regulates human neurodevelopment, and that increased PTEN dosage in brain organoids results in microcephaly-like phenotypes.

scholarly journals Glandular epithelial AR inactivation enhances PTEN deletion-induced uterine pathology

2016 ◽  
Vol 23 (5) ◽  
pp. 377-390 ◽  
Author(s):  
Jaesung (Peter) Choi ◽  
Yu Zheng ◽  
David J Handelsman ◽  
Ulla Simanainen
Keyword(s):  
Estrogen Receptor Alpha ◽  
Uterine Cancer ◽  
Intraepithelial Neoplasia ◽  
Glandular Epithelium ◽  
Wild Type ◽  
Double Knockout ◽  
Phosphatase And Tensin Homolog ◽  
Tensin Homolog ◽  
Pten Deletion ◽  
Uterine Growth

Phosphatase and tensin homolog (PTEN) deletion induces uterine pathology, whereas androgen actions via androgen receptor (AR) support uterine growth and therefore may modify uterine cancer risk. We hypothesized that the androgen actions mediated via uterine glandular epithelial AR could modify PTEN deletion-induced uterine pathology. To test our hypothesis, we developed uterine glandular epithelium-specific PTEN and/or AR knockout mouse models comparing the uterine pathology among wild-type (WT), glandular epithelium-specific AR inactivation (ugeARKO), PTEN deletion (ugePTENKO), and the combined PTEN and AR knockout (ugePTENARKO) female mice. The double knockout restricted to glandular epithelium showed that AR inactivation enhanced PTEN deletion-induced uterine pathology with development of intraepithelial neoplasia by 20 weeks of age. In ugePTENARKO, 6/10 (60%) developed intraepithelial neoplasia, whereas 3/10 (30%) developed only glandular hyperplasia in ugePTENKO uterus. No uterine pathology was observed in WT (n=8) and ugeARKO (n=7) uteri. Uterine weight was significantly (P=0.002) increased in ugePTENARKO (374±97 mg (mean±s.e.)) compared with WT (97±6 mg), ugeARKO (94±12 mg), and ugePTENKO (205±33 mg). Estrogen receptor alpha (ERα) and P-AKT expression was modified by uterine pathology but did not differ between ugePTENKO and ugePTENARKO, suggesting that its expressions are not directly affected by androgens. However, progesterone receptor (PR) expression was reduced in ugePTENARKO compared to ugePTENKO uterus, suggesting that PR expression could be regulated by glandular epithelial AR inactivation. In conclusion, glandular epithelial AR inactivation (with persistent stromal AR action) enhanced PTEN deletion-induced uterine pathology possibly by downregulating PR expression in the uterus.

scholarly journals PTENSequence Analysis in Endometrial Hyperplasia and Endometrial Carcinoma in Slovak Women

2015 ◽  
Vol 2015 ◽  
pp. 1-7 ◽  
Author(s):  
H. Gbelcová ◽  
P. Bakeš ◽  
P. Priščáková ◽  
V. Šišovský ◽  
I. Hojsíková ◽  
...  
Keyword(s):  
Tumor Suppressor ◽  
Endometrial Carcinoma ◽  
Endometrial Hyperplasia ◽  
Female Genital Tract ◽  
Suppressor Gene ◽  
Serous Carcinoma ◽  
Tissue Samples ◽  
Phosphatase And Tensin Homolog ◽  
Coding Regions ◽  
Tensin Homolog

Phosphatase and tensin homolog (PTEN) is a protein that acts as a tumor suppressor by dephosphorylating the lipid second messenger phosphatidylinositol 3,4,5-trisphosphate. Loss of PTEN function has been implicated in the pathogenesis of a number of different tumors, particularly endometrial carcinoma (ECa). ECa is the most common neoplasia of the female genital tract. Our study evaluates an association between the morphological appearance of endometrial hyperplasia and endometrial carcinoma and the degree ofPTENalterations. A total of 45 endometrial biopsies from Slovak women were included in present study. Formalin-fixed and paraffin-embedded tissue samples with simple hyperplasia (3), complex hyperplasia (5), atypical complex hyperplasia (7), endometrioid carcinomas G1 (20) and G3 (5), and serous carcinoma (5) were evaluated for the presence of mutations in coding regions ofPTENgene, the most frequently mutated tumor suppressor gene in endometrial carcinoma. 75% of the detected mutations were clustered in exons 5 and 8. Out of the 39 mutations detected in 24 cases, 20 were frameshifts and 19 were nonsense, missense, or silent mutations. Some specimens harboured more than one mutation. The results of current study on Slovak women were compared to a previous study performed on Polish population. The two sets of results were similar.

scholarly journals BRCA1-IRIS promotes human tumor progression through PTEN blockade and HIF-1α activation

2018 ◽  
Vol 115 (41) ◽  
pp. E9600-E9609 ◽  
Author(s):  
Andrew G. Li ◽  
Elizabeth C. Murphy ◽  
Aedin C. Culhane ◽  
Emily Powell ◽  
Hua Wang ◽  
...  
Keyword(s):  
Tumor Progression ◽  
Human Cancer ◽  
Human Tumor ◽  
Suppressor Gene ◽  
Phosphatase And Tensin Homolog ◽  
Human Cancer Cells ◽  
Tensin Homolog ◽  
Multiple Protein ◽  
Gsk 3Β ◽  
Cancer Suppression

BRCA1 is an established breast and ovarian tumor suppressor gene that encodes multiple protein products whose individual contributions to human cancer suppression are poorly understood. BRCA1-IRIS (also known as “IRIS”), an alternatively spliced BRCA1 product and a chromatin-bound replication and transcription regulator, is overexpressed in various primary human cancers, including breast cancer, lung cancer, acute myeloid leukemia, and certain other carcinomas. Its naturally occurring overexpression can promote the metastasis of patient-derived xenograft (PDX) cells and other human cancer cells in mouse models. The IRIS-driven metastatic mechanism results from IRIS-dependent suppression of phosphatase and tensin homolog (PTEN) transcription, which in turn perturbs the PI3K/AKT/GSK-3β pathway leading to prolyl hydroxylase-independent HIF-1α stabilization and activation in a normoxic environment. Thus, despite the tumor-suppressing genetic origin of IRIS, its properties more closely resemble those of an oncoprotein that, when spontaneously overexpressed, can, paradoxically, drive human tumor progression.

scholarly journals Therapeutic Implications of Targeting AKT Signaling in Melanoma

2011 ◽  
Vol 2011 ◽  
pp. 1-20 ◽  
Author(s):  
SubbaRao V. Madhunapantula ◽  
Gavin P. Robertson
Keyword(s):  
Pi3k Pathway ◽  
Term Treatment ◽  
Negative Regulator ◽  
Phosphatase And Tensin Homolog ◽  
Key Enzymes ◽  
Therapeutic Implications ◽  
Cellular Processes ◽  
Tensin Homolog ◽  
Stage Disease ◽  
Long Term Treatment

Identification of key enzymes regulating melanoma progression and drug resistance has the potential to lead to the development of novel, more effective targeted agents for inhibiting this deadly form of skin cancer. The Akt3, also known as protein kinase B gamma, pathway enzymes regulate diverse cellular processes including proliferation, survival, and invasion thereby promoting the development of melanoma. Accumulating preclinical evidence demonstrates that therapeutic agents targeting these kinases alone or in combination with other pathway members could be effective for the long-term treatment of advanced-stage disease. However, currently, no selective and effective therapeutic agent targeting these kinases has been identified for clinical use. This paper provides an overview of the key enzymes of the PI3K pathway with emphasis placed on Akt3 and the negative regulator of this kinase called PTEN (phosphatase and tensin homolog deleted on chromosome 10). Mechanisms regulating these enzymes, their substrates and therapeutic implications of targeting these proteins to treat melanoma are also discussed. Finally, key issues that remain to be answered and future directions for interested researchers pertaining to this signaling cascade are highlighted.

scholarly journals Essential role for autophagy protein ATG7 in the maintenance of intestinal stem cell integrity

2020 ◽  
Vol 117 (20) ◽  
pp. 11136-11146 ◽  
Author(s):  
Coralie Trentesaux ◽  
Marie Fraudeau ◽  
Caterina Luana Pitasi ◽  
Julie Lemarchand ◽  
Sébastien Jacques ◽  
...  
Keyword(s):  
Dna Damage ◽  
Stem Cell ◽  
Intestinal Epithelium ◽  
Tumor Formation ◽  
Intestinal Stem Cells ◽  
Intestinal Stem Cell ◽  
Intestinal Epithelial ◽  
Cell Integrity ◽  
Autophagy Gene ◽  
Defective Dna Repair

The intestinal epithelium acts as a barrier between the organism and its microenvironment, including the gut microbiota. It is the most rapidly regenerating tissue in the human body thanks to a pool of intestinal stem cells (ISCs) expressing Lgr5. The intestinal epithelium has to cope with continuous stress linked to its digestive and barrier functions. Epithelial repair is crucial to maintain its integrity, and Lgr5-positive intestinal stem cell (Lgr5+ISC) resilience following cytotoxic stresses is central to this repair stage. We show here that autophagy, a pathway allowing the lysosomal degradation of intracellular components, plays a crucial role in the maintenance and genetic integrity of Lgr5+ISC under physiological and stress conditions. Using conditional mice models lacking the autophagy gene Atg7 specifically in all intestinal epithelial cells or in Lgr5+ISC, we show that loss of Atg7 induces the p53-mediated apoptosis of Lgr5+ISC. Mechanistically, this is due to increasing oxidative stress, alterations to interactions with the microbiota, and defective DNA repair. Following irradiation, we show that Lgr5+ISC repair DNA damage more efficiently than their progenitors and that this protection is Atg7 dependent. Accordingly, we found that the stimulation of autophagy on fasting protects Lgr5+ISC against DNA damage and cell death mediated by oxaliplatin and doxorubicin treatments. Finally, p53 deletion prevents the death of Atg7-deficient Lgr5+ISC but promotes genetic instability and tumor formation. Altogether, our findings provide insights into the mechanisms underlying maintenance and integrity of ISC and highlight the key functions of Atg7 and p53.

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