Abstract B84: NADPH oxidase 1 (NOX1) and related NOX isoforms as key mediators of NFκB signaling in colon cancer

Abstracts: Frontiers in Cancer Prevention Research 2008 B84 NADPH oxidase/dual-oxidase (Nox/Duox) family members have been implicated in nuclear factor kappa-B (NFκB)-mediated inflammation and inflammation-associated pathologies. In rats given 2-amino-1-methyl-6-phenylimidazo[4,5- b ]pyridine (PhIP) alternating with a high-fat diet, Nox1, Nox4 and Duo2, but not Nox2, were over-expressed in colon tumors at 1 year, as shown by quantitative RT-PCR and immunoblotting. Over-expression of Nox/duox isoforms coincided with increased nuclear NFκB protein, and elevated levels of downstream targets IL-1 β , IL6 , TNF- α and TNFR1 . Over-expression of Nox1 and activation of NFκB also occurred at early stages of colon carcinogenesis, prior to tumor development. Nox/Duox isoforms were over-expressed in primary human colon cancers and in several human colorectal cancer cell lines. In HT29 cells, silencing of Nox1 inhibited nuclear translocation and DNA binding activity of NFκB, attenuated downstream targets IL1β, c-myc, and cyclin D1, and blocked lipopolysaccharide-induced phosphorylation of IκB kinaseα/β, resulting in G1 arrest. We conclude that the Nox1-NFκB pathway is important in colon tumorigenesis, and that Nox1 may provide a target for novel therapeutic strategies against colon cancer development. Citation Information: Cancer Prev Res 2008;1(7 Suppl):B84.