Radioresistance and Cancer Stem Cells: Survival of the Fittest

Copyright: © 2011 Sun L, et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Cancer arises from the accumulation of genetic mutations and aberrant epigenetic modifications in normal cells. Cancer stem cells (CSCs) have been described as a unique tumorigenic population of cells within the tumor mass that have the ability to self-renew and differentiate. In the past few years, the existence and nature of CSCs has served as one of the most controversial topics in the field of cancer biology; however, more recently, there is an abundant amount of evidence that demonstrates their existence. CSCs are believed to be responsible for resistance against conventional therapies, such as radiotherapy that contributes to uncontrolled tumor growth, metastasis and subsequently, patient demise. In this review, we summarize the mechanism(s) by which CSCs are radioresistant, including their enhanced DNA damage response, cell cycle status and the role of the CSC niche. Moreover, by usin