Researchers may have stumbled onto a new and rare kind of adult stem cell in adult male mice -- castration-resistant Nkx3.1-expressing cells or CARNs -- that may be a source of prostate cancer, according to a Columbia University study.

Found inside the ducts of the mouse prostate, CARNs are not only involved in the regeneration of prostate tissue, they can trigger the development of cancer if certain tumor suppressor genes (PTEN) in the cells are inactive. Before this discovery of adult stem cells in the luminal layer, cancer researchers assumed stem cells resided only in the basal (lowest) layer of the prostate.

The trick: Finding the same kinds of cells in the prostate glands of human males. Also, the PTEN genes are frequently mutated in human prostate cancers.

However, researchers were quick to point out their discovery of CARNs doesn't prove the existence of cancer stem cells, cells inside a tumor that have the ability to regenerate cancer from a single cell.

Nature September 9, 2009

EurekAlert September 9, 2009

healthfinder.gov September 9, 2009