Reactive oxygen species: Current knowledge and applications in cancer research and therapeutic

Reactive oxygen species (ROS) are natural products inevitably generated along cellular metabolism. Due to their highly reactive nature, which can damage DNA, proteins and lipids, cells utilize antioxidative or defense systems to balance these toxic products to keep the cells in a state of redox homeostasis. However, under the situation of imbalance in redox status, depending on the magnitude of ROS encountered, high levels of ROS can induce apoptosis, whereas chronic low levels of ROS promote vascular diseases such as arteriosclerosis. Although ROS seem to be catastrophic to life, accumulating evidence points to the beneficial roles of ROS by virtue of the ability as chemotherapeutic agents to cure human diseases. Many anti‐cancer drugs have been developed in this way which can generate ROS and cause oxidative stress‐induced apoptosis in cancer cells. The effects of ROS are paradoxical because they can act as both disease culprits and chemotherapeutic agents. In this review, the current knowledge of ROS and the potential applications of ROS in cancer therapeutic will be discussed. J. Cell. Biochem. 104: 657–667, 2008. © 2008 Wiley‐Liss, Inc.