| Prostate cancer is a highly prevalent disease in elderly men, which is treatable at early stages, yet causes morbidity and death upon progression to a hormone resistant, metastatic stage. Given prostate cancer's propensity to metastasize to the bone marrow and escape from androgen deprivation, the role of the bone marrow microenvironment in enabling castration resistant growth was examined using human bone marrow derived mesenchymal stem cells (hMSCs). The effect of bone marrow derived extracellular matrix (BM-ECM) secreted by hMSCs was examined on LNCaPs and MDa-PCa-2bs, and found to cause cell survival in both cell lines in androgen depleted conditions as well as chemoresistance in LNCaPs. Phosphoproteomic analysis identified p-ERK as increased in LNCaP cells grown on BM-ECM. The use of the specific MEK inhibitor U0126 was able to reverse the survival advantage LNCaPs grown on BM-ECM in androgen depleted conditions. Finally, human primary prostate tumors and bone metastases were examined for p-ERK levels and significantly more p-ERK in bone metastases than primary tumors was found.;In the second part of this work, it was hypothesized that quantitatively measuring the activation of cell signaling pathways in response to ligand treatments would enable understanding how cell signaling causes castration resistant growth. Three cell lines (PC3, LNCaP, and MDA-PCa-2b) were treated with 6 treatments (EGF, IGF1, IL6, TNFα, dihydrotestosterone, and docetaxel) and the alterations in 8 key phosphoproteins were measured across three time points. LNCaPs were also treated in combination with the targeted kinase inhibitors against MEK, PI3K, mTOR, IKK, and p38 resulting in 3400 phosphoprotein measurements. For each treatment the corresponding cell survival in androgen depleted conditions was assessed. A regression model correlating phosphoprotein measurements to survival data was able to account for the majority of the variation in cell survival. The effect of androgen on the phosphoproteome was also observed and seen to increase PI3K related proteins, and the innate signaling differences between the cell lines were observed. This regression analysis was also employed to successfully describe the polarization of macrophages to the M2 (tumor associated macrophage) versus M1 phenotype based on cell signaling alterations in response to ligand treatment. |
