Project description:mTOR is a serine/threonine kinase that controls prostate cancer (PCa) cell growth in part by regulating gene programs associated with metabolic and cell proliferation pathways. mTOR- mediated control of gene expression can be achieved via phosphorylation of transcription factors, leading to changes in their cellular localization and activities. mTOR also directly associates with chromatin in complex with transcriptional regulators, including the androgen receptor (AR). Nuclear mTOR (nmTOR) has been previously shown to act as a transcriptional integrator of the androgen signaling pathway in association with the chromatin remodeling machinery, AR, and FOXA1. However, the contribution of cytoplasmic mTOR (cmTOR) and nmTOR and the role played by FOXA1 in this process remains to be explored. Herein, we engineered cells expressing mTOR tagged with nuclear localization and export signals dictating mTOR localization. Transcriptome profiling in AR-positive PCa cells revealed that nmTOR generally downregulates a subset of the androgen response pathway independently of its kinase activity, while cmTOR upregulates a cell cycle-related gene signature in a kinase-dependent manner. Biochemical and genome-wide transcriptomic analyses demonstrate that nmTOR functionally interacts with AR and FOXA1. Ablation of FOXA1 reprograms the nmTOR cistrome and transcriptome of androgen responsive PCa cells. This works highlights a transcriptional regulatory pathway in which direct interactions between nmTOR, AR and FOXA1 dictate a combinatorial role for these factors in the control of specific gene programs in PCa cells.
Project description:mTOR is a serine/threonine kinase that controls prostate cancer (PCa) cell growth in part by regulating gene programs associated with metabolic and cell proliferation pathways. mTOR- mediated control of gene expression can be achieved via phosphorylation of transcription factors, leading to changes in their cellular localization and activities. mTOR also directly associates with chromatin in complex with transcriptional regulators, including the androgen receptor (AR). Nuclear mTOR (nmTOR) has been previously shown to act as a transcriptional integrator of the androgen signaling pathway in association with the chromatin remodeling machinery, AR, and FOXA1. However, the contribution of cytoplasmic mTOR (cmTOR) and nmTOR and the role played by FOXA1 in this process remains to be explored. Herein, we engineered cells expressing mTOR tagged with nuclear localization and export signals dictating mTOR localization. Transcriptome profiling in AR-positive PCa cells revealed that nmTOR generally downregulates a subset of the androgen response pathway independently of its kinase activity, while cmTOR upregulates a cell cycle-related gene signature in a kinase-dependent manner. Biochemical and genome-wide transcriptomic analyses demonstrate that nmTOR functionally interacts with AR and FOXA1. Ablation of FOXA1 reprograms the nmTOR cistrome and transcriptome of androgen responsive PCa cells. This works highlights a transcriptional regulatory pathway in which direct interactions between nmTOR, AR and FOXA1 dictate a combinatorial role for these factors in the control of specific gene programs in PCa cells.
Project description:5α-androstane-3α,17β-diol (3α-diol) is reduced from the potent androgen, 5α-dihydrotestosterone (5α-DHT), by reductive 3α-hydroxysteroid dehydrogenases (3α-HSDs). 3α-diol is believed to be a weak androgen, and has to be oxidized to 5α-DHT before it can exert its androgenic activity on androgen target tissues including the prostate. However, we repeatedly demonstrated that 3α-diol can be a potent androgen, activates cytoplasmic signaling pathway, and may be responsible for androgen-independent prostate cancer growth. A cancer-specific, cDNA-based membrane array was used to determine 3α-diol-mediated gene expressions in prostate cancer progression. Several canonical pathways appeared to be affected by 3α-diol-regulated signaling in LNCaP cells; among them are apoptosis signaling, PI3K/Akt signaling, and death receptor signaling pathways. Biological analysis of 3α-diol-activated signaling confirmed that 3α-diol augmented PI3K/Akt activation can be independent from the classical androgen receptor (AR) signaling. These observations sustained our previous report that 3α-diol continues to supported prostate cell survival and proliferation regardless the status of the AR. We provided the first global analysis of 3α-diol-activated gene expressions and identified cytoplasmic signaling pathways as important components of this response in human prostate cells. 3α-diol may play, therefore, a significant role for transition from androgen-dependent to androgen-independent prostate cancer progression in the presence of androgen blockade. Keywords: array, time course, androgen, prostate, cancer
Project description:Growing studies support a direct role for nuclear mTOR in gene regulation and chromatin structure. Still, the scarcity of known chromatin-bound mTOR partners limits our understanding of how nuclear mTOR controls transcription. Herein, we comprehensively mapped the mTOR chromatin-bound interactome in four cellular models of prostate cancer (PCa) identifying a conserved 67-protein interaction network enriched for epigenetic and transcription factors as well as SUMOylation machinery in both androgen-dependent and -independent cells. Notably, SUMO2/3 and nuclear pore protein NUP210 are among the strongest interactors while the androgen receptor (AR) is the dominant androgen-inducible mTOR partner. Further investigation showed that NUP210 facilitates mTOR nuclear trafficking, that mTOR, AR and NuRD act as a functional transcriptional complex, and that androgens dictate mTOR-SUMO2/3 promoter-enhancer specificity. This work identifies a vast network of mTOR-associated nuclear complexes advocating novel molecular strategies to modulate mTOR-dependent gene regulation with evident implications for PCa and other diseases.
Project description:Whether the nuclear fraction of mTOR plays a role in prostate cancer (PCa) and can participate in direct transcriptional crosstalk with the androgen receptor (AR) is as yet unknown. The intersection of gene expression, DNA binding-events, and metabolic studies uncovered the existence of a nuclear mTOR-AR transcriptional axis dictating the metabolic rewiring and nutrient usage of PCa cells. In human clinical specimens, nuclear localization of mTOR was significantly associated with metastasis and castration-resistant PCa (CRPC), correlating with a sustained metabolic gene program governed by mTOR in that context. This study thus uncovers an unexpected function of mTOR and underscores a paradigm shift from AR to mTOR as being the master transcriptional regulator of cell metabolism during PCa progression. We used microarrays to investigate the role of nuclear mTOR in prostate cancer cell transcriptional regulation by androgens in LNCaP cells.
Project description:Whether the nuclear fraction of mTOR plays a role in prostate cancer (PCa) and can participate in direct transcriptional crosstalk with the androgen receptor (AR) is as yet unknown. The intersection of gene expression, DNA binding-events, and metabolic studies uncovered the existence of a nuclear mTOR-AR transcriptional axis dictating the metabolic rewiring and nutrient usage of PCa cells. In human clinical specimens, nuclear localization of mTOR was significantly associated with metastasis and castration-resistant PCa (CRPC), correlating with a sustained metabolic gene program governed by mTOR in that context. This study thus uncovers an unexpected function of mTOR and underscores a paradigm shift from AR to mTOR as being the master transcriptional regulator of cell metabolism during PCa progression. We performed ChIP-seq of mTOR to study its role in LNCaP cells with or without androgen stimulation. The study was done twice independently; processed data are shown as a pool of either vehicle-treated samples or R1881-treated samples.
Project description:Both the PI3K/AKT/mTOR and androgen receptor (AR) signaling pathways play essential roles in prostate cancer. We compared the impact of PI3K/AKT/mTOR pathway inhibitors with different selectivity profiles on in vitro cell proliferation and apoptosis induction, and observed the strongest effects in androgen-sensitive prostate cancer models. Combination treatment with the AR inhibitor darolutamide led to enhanced apoptosis in these cell lines, with most pronounced effects of the pan-PI3K inhibitor copanlisib. Transcriptomic analysis performed in the androgen-sensitive VCaP cell line revealed that gene expression was more affected by the co-treatment with darolutamide and copanlisib, compared to single agents. A comprehensive reversal of the androgen response and the mTORC1 transcriptional programs was observed. The combination treatment also markedly induced DNA damage. An in vivo efficacy study performed using LuCaP 35, an androgen-sensitive patient-derived prostate cancer model, indicated superior efficacy after combined treatment with copanlisib and darolutamide. Immunohistochemistry analysis of treated tumors furthermore showed increased apoptosis. Altogether these data demonstrate that blocking the PI3K/AKT/mTOR and AR pathways with potent inhibitors has superior anti-tumor efficacy and induces apoptosis in androgen-sensitive prostate cancer models.
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.