The complex nature of cancer metastasis necessitates the development of a cancer model based on specific metastatic stages. In this dissertation, we report a polymer-nanoclay based in vitro tumor model which recapitulates early stage of prostate cancer skeletal metastasis. A unique cell culture system termed as ‘sequential culture’ has been applied to create a bone-mimetic niche for colonization of prostate cancer cells. Sequentially cultured MDA PCa 2b cells with MSCs formed self-organized multicellular tumoroids with distinct tight cellular junctions and hypoxic core regions. Further, the sequentially cultured PC-3 cell formed multicellular tumoroid like clusters. We performed immunocytochemical confocal microscopy, qRT-PCR, ELISA assays, nanomechanical evaluation and SEM imaging to characterize our tumor model. We observed that in the in vitro model that MSCs differentiated to matured osteoblasts, EMT (epithelial to mesenchymal transition) was inhibited, MET was enhanced, and hypoxia increased angiogenesis when prostate cancer cells were sequentially cultured with MSCs. We also studied the effect of prostate cancer metastasis on bone microenvironment using different prostate cancer cell lines. We found that the less metastatic MDA PCa 2b cells inhibited mineralized collagen formation whereas, highly metastatic PC-3 cells enhanced mineralized collagen formation. All the experimental results indicated osteoblastic bone formation by PC-3 cells and osteolytic bone resorption by MDA PCa 2b cells. Cancer metastasis is a complex process requiring dramatic remodeling of the cell cytoskeleton. Bone metastasis is characterized by complex biochemical, morphological, pathophysiological, and genetic changes to cancer cells as they colonize at remote bone sites. These changes can be captured in sum by changes to nanomechanical properties of cancer cells during metastasis. Using a specially designed nanoindentation apparatus, we observed significant softening of prostate cancer cells during MET and then further softening during the disease progression at the metastatic site. We observed a substantial reduction in elastic modulus of prostate cancer cells during MET arising from actin reorganization and depolymerization. This is the first study that reveals changes to nanomechanical characteristics of prostate cancer cells with correlation to cytoskeletal changes during MET and progression of the disease at the metastatic bone site.