Normal prostate tissues consist mainly of epithelial cells, including secretory epithelial cells, basal cells, and neuroendocrine cells, and of mesenchymal cells, including smooth muscle cells and fibroblasts. The mechanisms leading to castration resistant prostate cancer (CRPC) are complex and diverse, but most involve neuroendocrine differentiation. In fact, during the development of prostate cancer, some of the tumor cells transform into neuroendocrine-like cells. This transition is a main underlying mechanism of CRPC formation.