The free radical nitric oxide (NO
●) is known to play a dual role in human physiology and pathophysiology. At low levels, NO
● can protect cells; however, at higher levels, NO
● is a known cytotoxin, having been implicated in tumor
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The free radical nitric oxide (NO
●) is known to play a dual role in human physiology and pathophysiology. At low levels, NO
● can protect cells; however, at higher levels, NO
● is a known cytotoxin, having been implicated in tumor angiogenesis and progression. While the majority of research devoted to understanding the role of NO
● in cancer has to date been tissue-specific, we herein review underlying commonalities of NO
● which may well exist among tumors arising from a variety of different sites. We also discuss the role of NO
● in human physiology and pathophysiology, including the very important relationship between NO
● and the glutathione-transferases, a class of protective enzymes involved in cellular protection. The emerging role of NO
● in three main areas of epigenetics—DNA methylation, microRNAs, and histone modifications—is then discussed. Finally, we describe the recent development of a model cell line system in which human tumor cell lines were adapted to high NO
● (HNO) levels. We anticipate that these HNO cell lines will serve as a useful tool in the ongoing efforts to better understand the role of NO
● in cancer.
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