Association of reactive oxygen species levels and radioresistance in cancer stem cells. Nature 458

Metabolism of oxygen, while central to life, also produces reactive oxygen species (ROS) that have been implicated in processes as diverse as cancer, cardiovascular disease, and aging. It has recently been shown that central nervous system stem cells1, 2 and hematopoietic stem cells and early progenitors3-6 contain lower levels of ROS than their more mature progeny and that these differences appear to be critical for maintaining stem cell function. We hypothesized that epithelial tissue stem cells and their cancer stem cell (CSC) counterparts may also share this property. Here we show that normal mammary epithelial stem cells contain lower concentrations of ROS than their more matur