Prostatic tumor stroma: a key player in cancer progression.

Although it is evident that prostatic epithelial stem cells are responsible for maintaining normal and malignant tissues, it is well recognized that epithelial cells do not exist independently, but act in concert with the stromal microenvironment. Prostatic stroma is pivotal for normal development and homeostasis. The genetic and morphological changes that occur in prostatic epithelial cells, as they progress from a normal to malignant phenotype, have been well described. However, it is evident that the surrounding microenvironment also plays a major role in cancer cell growth, survival, invasion and metastatic progression. Prostatic tumor stroma provides a niche environment for cancer stem cells and therefore contributes to self-renewal and differentiation. In order to target the tumor microenvironment and develop new therapeutics for prostate cancer, we must understand the role of the tumor stroma, specifically the events mediating the interactions between the cancer stem cell and its immediate microenvironment during cancer initiation and progression. This article presents the rationale and discusses the challenges to targeting prostatic tumor stroma in cancer therapies that will potentially treat prostate cancer.