The growth of actively proliferating tumors requires the initiation of new blood vessel production by an unknown trigger, often referred to as the 'angiogenic switch'. In January 22 Proceedings of the National Academy of Sciences, Jack Arbiser and colleagues from Emory University School of Medicine, Atlanta, US show that reactive oxygen generated by Nox1 is an important trigger of angiogenesis.

Arbiser et al. found that vascular endothelial growth factor (VEGF) mRNA becomes markedly up regulated by Nox1 both in cultured cells and in tumors, and VEGF receptors (VEGFR1 and VEGFR2) are highly induced in the vascular tissue from Nox1-expressing tumors. In addition, Nox1 also induces matrix metalloproteinase activity, another marker of the angiogenic switch (Proc Natl Acad Sci USA 2002, 99:715-720).

"These findings point for the first time to uncontrolled generation of reactive oxygen and to Nox enzymes as a possible cause in the progression...