Pancreatic cancer stem cells: implications for the treatment of pancreatic cancer.

Pancreatic cancer is a highly lethal disease that is usually diagnosed at a late stage for which there are few effective therapies. Emerging evidence has suggested that malignant tumors are quite heterogeneous and that they are composed of a small subset of distinct cancer cells (usually defined by cell surface marker expression) that are responsible for tumor initiation and propagation, termed cancer stem cells. These cells are termed cancer stem cells because, like normal stem cells, they possess the ability to self-renew and make differentiated progeny. Recent studies of human pancreatic cancers have shown a population of pancreatic cancer stem cells that have aberrantly activated developmental signaling pathways, are resistant to standard chemotherapy and radiation, and have up-regulated signaling cascades that are integral for tumor metastasis. An improved understanding of the biological behavior of these cells may lead to more effective therapies to treat pancreatic cancer. In this review, approaches to develop and test therapeutics targeting pancreatic cancer stem cells are discussed.