PTEN suppresses neoplastic transformation of human neural stem cells by transcriptional repression of Pax7
Ontology highlight
ABSTRACT:
ORGANISM(S): Homo sapiens
PROVIDER: GSE61794 | GEO | 2015/09/26
SECONDARY ACCESSION(S): PRJNA262146
REPOSITORIES: GEO
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Project description:Glioblastoma (GBM) is a highly lethal brain tumor presenting as one of two subtypes with distinct clinical histories and molecular profiles. The primary GBM subtype presents acutely as high-grade disease that typically harbors EGFR, PTEN and Ink4a/Arf mutations, and the secondary GBM subtype evolves from the slow progression of low-grade disease that classically possesses PDGF and p53 events1. Here, we show that concomitant CNS-specific deletion of p53 and Pten in the mouse CNS generates a penetrant acute-onset high-grade malignant glioma phenotype with striking clinical, pathological and molecular resemblance to primary GBM in humans. This genetic observation prompted p53 and PTEN mutational analysis in human primary GBM, demonstrating unexpectedly frequent inactivating mutations of p53 as well the expected PTEN mutations. Integrated transcriptomic profling, in silico promoter analysis and functional studies of murine neural stem cells (NSCs) established that dual, but not singular, inactivation of p53 and Pten promotes an undifferentiated state with high renewal potential and drives elevated c-Myc levels and its associated signature. Functional studies validated increased c-Myc activity as a potent contributor to the impaired differentiation and enhanced renewal of p53-Pten null NSCs as well as tumor neurospheres (TNSs) derived from this model. c-Myc also serves to maintain robust tumorigenic potential of p53-Pten null TNSs. These murine modeling studies, together with confirmatory transcriptomic/promoter studies in human primary GBM, validate a pathogenetic role of a common tumor suppressor mutation profile in human primary GBM and establish c-Myc as a key target for cooperative actions of p53 and Pten in the regulation of normal and malignant stem/progenitor cell differentiation, self-renewal and tumorigenic potential. We used microarrays to detail the gene expression difference of the p53-null and p53/Pten-doubly null neural stem cell after differentiation . Keywords: cell type comparison
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Project description:Prostate cancer (PCa) is the second leading cause of cancer death in men. Its clinical and molecular heterogeneity and the lack of in vitro models outline the complexity of PCa in the clinical and research settings. We established an in vitro mouse PCa model based on organoid technology that takes into account the cell of origin and the order of events. Primary PCa with deletion of the tumor suppressor gene PTEN (PTEN-del) can be modeled through Pten-downregulation in mouse organoids. We used this system to elucidate the contribution of TIP5 in PCa initiation, a chromatin regulator that is implicated in aggressive PCa. High TIP5 expression correlates with primary PTEN-del PCa and this combination strongly associates with reduced PSA recurrence-free survival. TIP5 is critical for the initiation of PCa of luminal origin mediated by Pten loss whereas it is dispensable once Pten-loss mediated transformation is established. Cross-species analyses revealed a PTEN gene signature that identified a group of aggressive primary PCa characterized by PTEN-deletion, high-TIP5 expression, and a TIP5-regulated gene expression profile. The results highlight the modelling of PCa with organoids as a powerful tool to elucidate the role of genetic alterations found in recent studies in their time order and cell of origin, thereby providing further optimization for tumour stratification to improve the clinical management of PCa.
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Project description:Lineage plasticity is a major mechanism driving prostate cancer progression and antiandrogen therapy resistance. Deletions or mutations in phosphatase and tensin homolog (PTEN) and TP53 tumor suppressor genes have been linked to lineage plasticity in prostate cancer. Fusion-driven overexpression of the E-twenty-six transformation specific (ETS)-related gene (ERG), encoding an oncogenic transcription factor, is observed in approximately 50% of all prostate cancers, yet its role in prostate cell lineage determination remains elusive. Here we demonstrate that transgenic expression of prostate cancer-associated ERG blocks Pten and Trp53 mutation-induced decreased expression of Ar and its downstream target genes and loss of luminal epithelial cell identity in the mouse prostate. Integrative analyses of ERG chromatin-immunoprecipitation sequencing (ChIP-seq) and transcriptome data show that ERG suppresses expression of a subset of cell cycle-promoting genes and RB phosphorylation, which in turn causes repression of E2F1-mediated expression of non-epithelial lineage genes. Xenograft studies show that PTEN/TP53 double mutated prostate tumors are responsive to the cyclin-dependent kinase 4 or 6 (CDK4/6) inhibitor palbociclib, but resistant to the AR inhibitor enzalutamide, while ERG/PTEN/TP53 triple-mutated prostate tumors behave completely opposite. Our studies identify ERG and the repressed cell cycle gene signature as intrinsic inhibitors of PTEN/TP53 double mutation-elicited lineage plasticity in prostate cancer. Our findings also suggest that ERG fusion can be utilized as a biomarker to guide the treatment of PTEN/TP53-mutated, RB1-intact prostate cancer with either antiandrogen or anti-CDK4/6 therapies.
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Project description:MicroRNAs (miRNAs) represent an important class of small regulatory RNAs that control gene expression posttranscriptionally by targeting mRNAs for degradation or translation inhibition. Early studies have revealed a complex role for miRNAs in major biological processes such as development, differentiation, growth and metabolism. MiR-137 in particular, has been of great interest due to its critical role in brain function and putative involvement in the etiology of both neuropsychiatric disorders and cancer. Several lines of evidence suggest that development, differentiation and maturation of the nervous system is strongly linked to the expression of miR-137 and its regulation of a large number of downstream target genes in various pathways. Dysregulation of this molecule has also been implicated in major mental illnesses through its position in a variant allele highly associated with schizophrenia in the largest mega genome-wide association studies. Interestingly, miR-137 has also been shown to act as a tumor suppressor, with numerous studies finding reduced expression in neoplasia including brain tumor. Restoration of miR-137 expression has also been shown to inhibit cell proliferation, migration and metastasis, and induce cell cycle arrest, differentiation and apoptosis. These properties of miR-137 propose its potential for prognosis, diagnosis and as a therapeutic target for treatment of several human neurological and neoplastic disorders. In this review, we provide details on the discovery, targets, function, regulation and disease involvement of miR-137 with a broad look at recent discovery in this area.
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Project description:After damage to the adult mammalian central nervous system (CNS), surviving neurons have limited capacity to regenerate and restore functional connectivity. Conditional genetic deletion of PTEN results in robust CNS axon regrowth, while PTEN repression with short hairpin RNA (shRNA) improves regeneration but to a lesser extent, likely due to suboptimal PTEN mRNA knockdown using this approach. Here we employed the CRISPR/dCas9 system to repress PTEN transcription in neural cells. We targeted the PTEN proximal promoter and 5' untranslated region with dCas9 fused to the repressor protein Krüppel-associated box (KRAB). dCas9-KRAB delivered in a lentiviral vector with one CRISPR guide RNA (gRNA) achieved potent and specific PTEN repression in human cell line models and neural cells derived from human iPSCs, and induced histone (H)3 methylation and deacetylation at the PTEN promoter. The dCas9-KRAB system outperformed a combination of four shRNAs targeting the PTEN transcript, a construct previously used in CNS injury models. The CRISPR system also worked more effectively than shRNAs for Pten repression in rat neural crest-derived PC-12 cells, and enhanced neurite outgrowth after nerve growth factor stimulation. PTEN silencing with CRISPR/dCas9 epigenetic editing may provide a new option for promoting axon regeneration and functional recovery after CNS trauma.
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Project description:PTEN is one of the most frequently mutated tumor suppressor genes, its loss has been reported in multiple tumor types and is associated with a poor outcome. PTEN-L, as a secreted isoform of PTEN, with the ability to enter cells and inhibit tumor cell growth via inhibiting AKT mediated cell proliferation. However, the distinct effect of PTEN-L on PTEN-expression or PTEN-loss tumor cells is not known yet. Here, we identified PTEN-L treatment facilitate E0771-PTEN-null tumor cells, but not PTEN-wide-type tumor cells lung outgrowth. RNA-seq and Western blot analysis suggest PTEN-L stimulation induced PTEN-null tumor cells dormancy, namely, upregulation of dormancy markers p16 and p27, cell cycle arrest, reduced cell proliferation and chemotherapy drugs resistance. Further study suggested PTEN-L mediated p38 signaling activation play the major role for PTEN-null tumor cell dormancy. The p38 inhibitor, SB202190 significantly reversed the PTEN-L induced PTEN-null tumor cells dormancy and outgrowth in lungs. Further investigation indicated the dormant PTEN-null tumor cells could escape from immunosurveillance and thus outgrowth in lungs, as PTEN-L did not promote PTEN-null tumor cells outgrowth in lung of SCID mice. Therefore, we propose that PTEN-L protects PTEN-null tumor cells from immune attack during lung metastasis via activating dormancy related pathways. This study identified PTEN-L as an activator of PTEN-loss tumor cells dormancy, which enables the efficient seeding and outgrowth of tumor cells in metastatic niches. Overall, we highlight PTEN expression status decides the outcome of PTEN-L mediated anti-tumor therapy.
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Project description:Nuclear localization of PTEN is essential for its tumor suppressive role, and loss of nuclear PTEN is more prominent than cytoplasmic PTEN in many kinds of cancers. However, nuclear PTEN-specific regulatory mechanisms were rarely reported. Based on the finding that nuclear PTEN is more unstable than cytoplasmic PTEN. Thus, 293T cells were transiently transfected with plasmid encoding Flag-tagged PTEN along with empty vector, followed by affinity purification using an anti-Flag antibody, and the bound proteins were analyzed by liquid chromatography with tandem mass spectrometry (LC−MS/MS). Here we identify that F-box only protein 22 (FBXO22) induces ubiquitylation of nuclear but not cytoplasmic PTEN at lysine 221, which is responsible for the degradation of nuclear PTEN.
2020-04-22 | PXD017983 | Pride