Prostate cancer stem cells.

The Cancer Stem Cells (CSCs) hypothesis postulates that a minute subpopulation of cells is accountable for cancer initiation and progression. Unlike the stochastic and clonal evolution models, the CSC theory proposes that tumours are hierarchical and only the rare subset of cells at the top of the 'stemness hierarchy tree' are adequately 'equipped' biologically to initiate and drive tumourigenesis. CSCs have been implicated in various solid malignancies including prostate cancer (PCa), where their existence seems to provide an explanation for the failure of tumour eradicating therapies. As CSCs are thought to share many properties with normal stem cells, understanding normal stem cells should shed light on the pathomechanisms of cancer and, importantly, on potential therapeutic interventions. The purpose of this paper is to review the existing data on CSCs in PCa, their putative phenotypic markers, potential role in tumour biology and relevance to therapy.