Molecular Profiling of the Tumor Microenvironment in Prostate Cancer Progression - PROJECT SUMMARY Development of metastatic castration resistant prostate cancer (mCRPC) is dictated by multiple signaling pathways that regulate apoptosis, the androgen axis, anoikis, epithelial-mesenchymal transition (EMT), cell plasticity, invasion and angiogenesis. Disruption of mechanisms underlying these processes and the phenotypic changes they drive within the tumor microenvironment (TME), is critical to overcoming therapeutic resistance and tumor recurrence in patients with advanced disease. The overall goal of this proposal is to determine the mechanisms that link conversion of EMT to mesenchymal-epithelial transition (MET) and anoikis to and progression to advanced therapeutically-resistant prostate cancer. We developed novel agents that target tumor epithelial and endothelial cells that induce anoikis (by inhibiting the AKT pathway) and prevent metastasis by reducing tumor cell adhesion to the extracellular matrix (ECM) and inhibit invasion in vivo. Our hypothesis is that intracellular re-programming of EMT and anoikis within the TME, promotes prostate tumor invasion to lymph nodes and tumor recurrence after prostatectomy in patients. Three Specific Aims will be addressed to gain knowledge of the mechanisms underlying anoikis resistance and lymph node invasion during prostate cancer progression. In Specific Aim 1, we hypothesize that TGF-β-mediated EMT is linked to anoikis resistance, and EMT to MET conversion facilitates anoikis induction and therapeutic response in mCRPC. Studies will determine mechanisms by which EMT programming facilitates prostate cancer cell configuration to a phenotype responsive to drug-induced anoikis in in vitro. Specific Aim 2 will identify the functional significance of extracellular vesicles (EVs) cargo in prostate cancer progression. We hypothesize that EVs contribute to anoikis resistance and tumor invasion through cargo dissemination. We will characterize EMT effectors in prostate cancer cells and EVs via multi-omics, contributing to a primed-to-die phenotype in pre-clinical models of advanced prostate cancer at different stages of tumor progression and correlate changes in EVs cargo with invasive properties. Specific Aim 3 will establish predictive signatures of lymph node invasion and prognostication in prostate cancer patients. We hypothesize that intercellular communications between primary prostate tumor cells and lymph nodes leads to cancer cell invasion, and EVs act as extracellular conveyors to facilitate lymph node invasion and metastatic spread. This Aim will establish new predictive profiles of molecular and phenotypic effectors in prostate tumors and in EVs in clinical progression of prostate cancer. The proposed studies will provide new insights into the mechanisms programming resistance to anoikis and EMT in the prostate TME in vitro and in vivo. The work will be of translational impact in: (a) defining the therapeutic value of anoikis-agents in conferring vulnerability in treating mCRPC; (b) establishing the role of EVs as contributors to lymph node invasion during tumor progression; and (c) identification of profiles (signatures) of lymph node invasion and tumor recurrence in prostate cancer patients with advanced disease.
