Project description:Recurrent point mutations in SPOP define a distinct molecular subclass of prostate cancer. Here, we describe the first mouse model showing that mutant SPOP drives prostate tumorigenesis in vivo. Conditional expression of mutant SPOP in the prostate dramatically altered phenotypes in the setting of Pten loss, with early neoplastic lesions (high-grade prostatic intraepithelial neoplasia) with striking nuclear atypia, and invasive poorly differentiated carcinoma. In mouse prostate organoids, mutant SPOP drove increased proliferation and a transcriptional signature consistent with human prostate cancer. Using these models and human prostate cancer samples, we show that SPOP mutation activates both PI3K/mTOR and androgen receptor (AR) signaling, effectively uncoupling the normal negative feedback between these two pathways. Associated RNA-seq data deposited in GEO: GSE94839.
Project description:Bromodomain and extraterminal domain (BET) protein inhibitors are emerging as promising therapeutics of cancers including prostate cancer. The E3 ubiquitin ligase adaptor protein speckle-type POZ protein (SPOP) is implicated in human prostate cancers due to its frequent mutation. Here we demonstrate that SPOP binds to the BET proteins BRD2, BRD3 and BRD4. Wild-type SPOP, but not prostate cancer-associated mutants, promotes polyubiquitination and proteasome degradation of BET proteins by recognizing a common degron motif. BET protein levels are highly elevated in SPOP-mutated prostate cancers in patients. Expression of cancer-derived SPOP mutants upregulates cholesterol biosynthesis genes and confers resistance to the BET inhibitor in cultured prostate cancer cells and tumors in mice, and this effect can be overcome by the AKT inhibitor. Our findings reveal BET proteins as proteolytic targets of SPOP and identify deregulated cholesterol biosynthesis as a downstream event of SPOP mutation-mediated tumorigenesis and therapy resistance in prostate cancer.
Project description:Bromodomain and extraterminal domain (BET) protein inhibitors are emerging as promising therapeutics of cancers including prostate cancer. The E3 ubiquitin ligase adaptor protein speckle-type POZ protein (SPOP) is implicated in human prostate cancers due to its frequent mutation. Here we demonstrate that SPOP binds to the BET proteins BRD2, BRD3 and BRD4. Wild-type SPOP, but not prostate cancer-associated mutants, promotes polyubiquitination and proteasome degradation of BET proteins by recognizing a common degron motif. BET protein levels are highly elevated in SPOP-mutated prostate cancers in patients. Expression of cancer-derived SPOP mutants upregulates cholesterol biosynthesis genes and confers resistance to the BET inhibitor in cultured prostate cancer cells and tumors in mice, and this effect can be overcome by the AKT inhibitor. Our findings reveal BET proteins as proteolytic targets of SPOP and identify deregulated cholesterol biosynthesis as a downstream event of SPOP mutation-mediated tumorigenesis and therapy resistance in prostate cancer.
Project description:Bromodomain and extraterminal domain (BET) protein inhibitors are emerging as promising therapeutics of cancers including prostate cancer. The E3 ubiquitin ligase adaptor protein speckle-type POZ protein (SPOP) is implicated in human prostate cancers due to its frequent mutation. Here we demonstrate that SPOP binds to the BET proteins BRD2, BRD3 and BRD4. Wild-type SPOP, but not prostate cancer-associated mutants, promotes polyubiquitination and proteasome degradation of BET proteins by recognizing a common degron motif. BET protein levels are highly elevated in SPOP-mutated prostate cancers in patients. Expression of cancer-derived SPOP mutants upregulates cholesterol biosynthesis genes and confers resistance to the BET inhibitor in cultured prostate cancer cells and tumors in mice, and this effect can be overcome by the AKT inhibitor. Our findings reveal BET proteins as proteolytic targets of SPOP and identify deregulated cholesterol biosynthesis as a downstream event of SPOP mutation-mediated tumorigenesis and therapy resistance in prostate cancer.
Project description:SPOP is a ubiquitin ligase adaptor frequently mutated in prostate cancer. It is involved in ubiquitination and degradation of substrate proteins. We examined the impact of wild-type and mutant SPOP on the transcriptional profile of prostate cancer cells. We cloned several naturally occurring (in human prostate cancer) SPOP mutants and expressed the corresponding constructs in prostate cancer cells. Our experimental conditions were: Human prostate cancer cells (LNCaP-Abl), transfected with control vector, SPOP-wt, and any of the following mutants: SPOP-F102C, SPOP-F133V, SPOP-F133L (2-4 biological replicates each). We analyzed their gene expression profiles for differences induced by SPOP-wt vs SPOP-mutant.
Project description:SPOP is known to bind to serine/theronine-rich degrons on substrate proteins. We identified two degron sequences within the PWWP and MYND domain of ZMYND11, a novel SPOP substrate, and investigated whether ZMYND11 may contribute to the transcriptional output of mutant SPOP in VCaP cancer cells. Hence, we performed over-expression of degron-deficient ZMYND11 and degron-deficient ZMYND11 with W294A mutation in VCaP cells. While WT ZMYND11 constructs can be robustly over-expressed at the mRNA level, only the degron-deficient variants yielded a robost increase in ZMYND11 protein expression. Degron mutant-induced transcriptional perturbations partially mimicked SPOP mutant-induced gene expression changes, suggesting that ZMYND11 is sufficient to recapitulate certain features of mutant SPOP.
Project description:SPOP is a ubiquitin ligase adaptor frequently mutated in prostate cancer. It is involved in ubiquitination and degradation of substrate proteins. We examined the impact of wild-type and mutant SPOP on the transcriptional profile of prostate cancer cells.
Project description:SPOP is known to bind to serine/theronine-rich degrons on substrate proteins. We identified two degron sequences within the PWWP and MYND domain of ZMYND11, a novel SPOP substrate, and investigated whether ZMYND11 may contribute to the transcriptional output of mutant SPOP in VCaP cancer cells. We mapped the genomic occupancy of ZMYND11 in VCaP cells over-expressing either wild type SPOP or the recurrent SPOP-Y87C mutant by ChIPseq. Genomic binding sites in the SPOP-Y87C mutant were increased over wild type SPOP, consistent with the increased ZMYND11 expression levels in the former.