Oxygen metabolism is key to eukaryotic life and important for signaling as well as metabolism. Yet, ROS are linked to cancer and aging as well as inflammation. There is also a possible link between stem cells and levels of ROS. With new in vivo imaging, and other methods ROS levels may be more evident at the individual cell level and in response to environmental stresses.
..first of all when compared with normal cells cancer cells mantain a high levels of ROS.. ROS have been shown to be toxic to cells leading to cell death. How do cancer cells survive in such a toxic environment..? answer is through aerobic glycolysis (Warburg effect )... Glycolyic by products especially lactic acid have antioxidant effects. However cancer stem cells mantain a lower level of ROS when compared to normal and cancer cells (J cell physiological 2012 227(2) 421-30., Cell Death dis. 2013 14;4:e537.doi:10.1038/caddis.2013.50.). As these cancer stem cells maintain a lower level of ROS when compared to nontumorigenic cells it endows them with radioresitance(nature 2009 458(7239):780-3.doi:10.1038/nature07733., Cell stem cell 2009 6;4(3):196-7.doi:10.1016/j.stem.2009.02.008.)
dear John Trainer
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.
you find enclosed some articles and links
http://www.nature.com/nrc/journal/v9/n3/full/nrc2614.html
..first of all when compared with normal cells cancer cells mantain a high levels of ROS.. ROS have been shown to be toxic to cells leading to cell death. How do cancer cells survive in such a toxic environment..? answer is through aerobic glycolysis (Warburg effect )... Glycolyic by products especially lactic acid have antioxidant effects. However cancer stem cells mantain a lower level of ROS when compared to normal and cancer cells (J cell physiological 2012 227(2) 421-30., Cell Death dis. 2013 14;4:e537.doi:10.1038/caddis.2013.50.). As these cancer stem cells maintain a lower level of ROS when compared to nontumorigenic cells it endows them with radioresitance(nature 2009 458(7239):780-3.doi:10.1038/nature07733., Cell stem cell 2009 6;4(3):196-7.doi:10.1016/j.stem.2009.02.008.)
In my knowledge some cancer stem cell exhibit low ROS level however, in some specific cancer stem cell exhibit higher level of ROS.
Another interesting point is that both tumor microenvironments and stem cell niches tend to be hypoxic. Depending on the metabolic rate of the cells this can lead to more or less ROS. A stem cell niche might be preserving itself from ROS during quiescence, conversely tumor stem cells might be driven to death while dividing in a hypoxic environment created by antiangiogenic drugs. It seems important to gauge the level of hypoxia, metabolic rate, and ROS buildup of a given niche or tumor model to get a real sense of what is going on.
This is a complex but interesting question. See a review by Gorrini et al. in Nature Reviews Drug Discovery, 2013.
Modulation of oxidative stress as an anticancer strategy
http://www.nature.com/nrd/journal/v12/n12/full/nrd4002.html
>Yet, ROS are linked to cancer and aging as well as inflammation. There is also a possible link between stem cells and levels of ROS.
A quick comment to this is that "ROS" is not a single entity but a collection of different chemical molecules with distinct chemical properties. Their formation kinetics, compartmentalization, half-life and reactivity almost all differ. At different stages of cancer progression, within the complex heterogeneous microenvironment, different ROS may wax and wane, contributing to the different fates of cells. It is often for this reason, antioxidant therapy involving a single drug intervention fails.
See Nat. Chem. Biol. review by Christine Winterbourn.
http://www.nature.com/nchembio/journal/v4/n5/abs/nchembio.85.html
And this recent one:
http://www.cell.com/cell-metabolism/abstract/S1550-4131%2811%2900097-0
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