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.
Project description:The current study defines the how ERG, PTEN, and AR inteact to regulate the transciptome in established prostate cancers. Prostate cancer organoids were derived from established prostate cancer in GEM models harboring ERG over-expression and/or loss of PTEN and cultured in vitro using prostate epithelial organoid culture conditions. The established organoids were then isolated as individual clones in triplicate and CRISPR strategies were employeed to knock out ERG and AR. RNA was isolated under physiologic steady state growth conditions and 24 hour treatment with the AR inhbitor MDV3100 in a subset of ERG-PTEN CRISPR ERG organoids.
Project description:Acute Pten loss initiates prostate tumorigenesis characterized by cellular senescence response. Here we examine the cellular senescence response in epithelial individual cells, by single-cell RNA sequencing (scRNAseq) in Ptenpc-/- and Ptenpc-/-; Timp1-/- GEMMs. ScRNAseq analysis determines a cluster of senescent cells expressing the senescence-related genes. A significant positive correlation is observed between the senescence score and Bcl2 expression. This provides the rational for targeting senescent cells using Bcl2 inhibitor.
Project description:The current study defines the how ERG, PTEN, and AR inteact to regulate the transciptome in established prostate cancers. Prostate cancer organoids were derived from established prostate cancer in GEM models harboring ERG over-expression and/or loss of PTEN and cultured in vitro using prostate epithelial organoid culture conditions. The established organoids were then isolated as individual clones in triplicate and CRISPR strategies were employeed to knock out ERG and AR. ChIP seq was performed under standard growth and media conditions.
Project description:We performed expression mouse profiling of prostates of 3 month WT, ERG, PTEN f/f and Pten f/f;ERG mice. For WT and ERG prostates, entire prostates were dissected and total RNA immediated harvested. For Pten f/f and Pten f/f;ERG prostates, the Ventral Lobe was dissected. Mice are in the C57B6 background. The prostate were harvested and RNA isolated by standard protocols and analyzed by expression profiling.
Project description:The TMPRSS2-ERG gene fusion is the most frequent alteration observed in human prostate cancer but its role in disease progression is still debated. In this study, we uncovered a novel molecular mechanism promoting progression in ERG-fusion positive prostate cancer. We show that ERG is methylated by Enhancer of zest homolog 2 (EZH2) at a specific lysine residue (K362) located within the internal auto-inhibitory domain. Mechanistically, K362 mono- methylation prevents intra-domain interactions, favors DNA binding and promotes ERG transcriptional and oncogenic activity in cellular and mouse models. Consistently with the involvement in ERG oncogenesis, we found that K362 methylation was associated with disease progression in ERG transgenic mouse models and was enhanced by PTEN deficiency and AKT activation, which promoted EZH2 substrate switching from histone H3K27 to ERG. Conversely, EZH2 inhibition blocked ERG methylation along with ERG-induced transcriptional and phenotypic reprogramming in cell cultures and ERG/PTEN mice. We found that ERG and EZH2 co-occupy several genomic regions forming prevalently co-activating complexes. The network of ERG/EZH2 co-regulated target genes was enriched of functionally aggressive features and was associated preferentially with concomitant ERG gain and PTEN loss, castration-resistance and adverse clinical outcome in prostate cancer patients. Collectively, these findings identify ERG methylation as a novel post-translational modification sustaining disease progression in ERG-positive prostate cancers. Our data also provide an attractive rationale for developing molecularly targeted therapeutics to antagonize ERG oncogenic activity.
Project description:To determine if ERG expression and PTEN loss were sufficient to transform prostate epithelial cells we constructed cell lines with expression of the TMPRSS2/ERG fusion gene (TE), stable knockdown of PTEN with shRNA (PTEN KD) or both alterations (PTEN KD/TE) using the PNT1A cell line. To determine what gene expression changes are associated the phenotypic changes between the cell line experimental groups, we carried expression microarray studies using Agilent 60K expression microarrays. RNAs from all four cell lines were analyzed in duplicate and probes with ≥ 1.4-fold or ≤0.7-fold relative to control cells identified. Our results demonstrated that PTEN loss and expression of the TMPRSS2/ERG fusion gene transform prostatic epithelial cells via enhanced FGF signaling.
Project description:Half of prostate cancers are caused by a gene-fusion that enables androgens to drive expression of the normally silent ETS transcription factor ERG in luminal prostate cells1-4. Recent prostate cancer genomic landscape studies5-10 have reported rare but recurrent point mutations in the ETS repressor ERF11. Here we show these ERF mutations cause decreased protein stability and ERF mutant tumours are mostly exclusive from those with ERG fusions. ERF loss recapitulates the morphologic and phenotypic features of ERG gain in primary mouse prostate tissue, including expansion of the androgen receptor (AR) transcriptional repertoire, and ERF has tumour suppressor activity in the same genetic background of PTEN loss that yields oncogenic activity by ERG. Furthermore, in a human prostate cancer model of ERG gain and wild-type ERF, ChIP-seq studies indicate that ERG inhibits the ability of ERF to bind DNA at consensus ETS sites. Consistent with a competition model, ERF loss rescues ERG-positive prostate cancer cells from ERG dependency. Collectively, these data provide evidence that the oncogenicity of ERG is mediated, in part, by displacement of ERF and raise the larger question of whether other gain-of-function oncogenic transcription factors might also inactivate endogenous tumour suppressors.
Project description:Half of prostate cancers are caused by a gene-fusion that enables androgens to drive expression of the normally silent ETS transcription factor ERG in luminal prostate cells1-4. Recent prostate cancer genomic landscape studies5-10 have reported rare but recurrent point mutations in the ETS repressor ERF11. Here we show these ERF mutations cause decreased protein stability and ERF mutant tumours are mostly exclusive from those with ERG fusions. ERF loss recapitulates the morphologic and phenotypic features of ERG gain in primary mouse prostate tissue, including expansion of the androgen receptor (AR) transcriptional repertoire, and ERF has tumour suppressor activity in the same genetic background of PTEN loss that yields oncogenic activity by ERG. Furthermore, in a human prostate cancer model of ERG gain and wild-type ERF, ChIP-seq studies indicate that ERG inhibits the ability of ERF to bind DNA at consensus ETS sites. Consistent with a competition model, ERF loss rescues ERG-positive prostate cancer cells from ERG dependency. Collectively, these data provide evidence that the oncogenicity of ERG is mediated, in part, by displacement of ERF and raise the larger question of whether other gain-of-function oncogenic transcription factors might also inactivate endogenous tumour suppressors.