Nitric Oxide: Perspectives and Emerging Studies of a Well Known Cytotoxin

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

The biology of caveolae: Achievements and perspectives

Caveolae are specialized plasma membrane subdomains visualized more than 50 years ago as cave-like invaginations at the cell surface. They are rich in cholesterol, glycosphingolipids, and lipid-anchored proteins. Their signaling and trafficking capabilities influence multiple cellular processes, and are believed to require caveolin-1, a major protein component of caveolae in most cell types. Today the structure and functions of caveolae are still the objects of intense research. Caveolin-1 is not anymore the only protein known to be required for caveolae formation, and functions for caveolin-1 outside of caveolae are being unveiled. Studying the phenotype of mice lacking caveolae has largely confirmed the roles attributed to this organelle and its defining protein. The consequences of mutation of ablation of caveolins in human disease are emerging. Recent evidence further suggests that caveolae and caveolin can be targeted for therapeutic purposes