Implications of cancer stem cells in the treatment of cancer.

Identification of cancer stem cells (CSCs) in both hematological and solid malignancies suggests that CSCs may be a common phenomenon for most malignancies. Similarly to normal stem cells, CSCs can self-renew and differentiate into progeny cancer cells. Almost all current therapy against cancer targets differentiated cancer cells. CSCs are more resistant to therapy secondary to quiescence, increased expression of antiapoptotic proteins and drug efflux transporters. In this article, we review the current status of CSC research and propose the targeting of CSC cell-surface molecules, signal transduction pathways, the stem cell niche, stem cell differentiation and drug resistance.