Possible Prostate Cancer Stem Cell

Buffalo, New York -

The tumor stem cell concept implies a small self-renewing population of cells in a tumor mass is responsible for maintaining the bulk of the tumor which comprises primarily of differentiated cells.  This was demonstrated by O'Brien et al in the case of colon cancer in which only the small, quiescent, CD133 cells from the tumor were capable of causing tumor growth in immune deficient animals. 

One of the biggest issues in identifying cancer stem cells is knowing what markers they express.  Perhaps even more interesting is the question of their healthy counterparts.  In a recent paper (Sotomayor et al. Oct4A is expressed by a subpopulation of prostate neuroendocrine cells. Prostate 2008 Dec 3) this topic was touched upon.

The investigators found that healthy prostates and malignant prostates had expression of the self-renewal marker Oct4A in a small proportion of cells.  These cells were negative for markers of basal epithelial cell or luminal epithelial cell differentiation, or AMACR, a marker of prostate cancer epithelial cells.  Interestingly, these cells also lacked more conventional cancer stem cell markers such as ABCG2, NANOG and CD133.  The cells did express Sox2 (also associated with self-renewal), and neuroendocrine differentiation markers. 

Why these cells may be related to cancer stem cells is that they are found in higher numbers in patient samples with higher Gleason scores.

It will be interesting to see how these putative cancer stem cells fit into the scheme of more "conventional" cancer stem cells such as CD133 positive ones.