2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (Synonyms: PhIP)

2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) is a food-derived carcinogen that is found in high temperature-cooked fish and meat. In humans, PhIP is metabolized by the cytochrome (CYP) P450 isoform CYP1A2 and conjugated by N-acetyltransferase or sulfotransferase to a metabolite that reacts with DNA to form adducts, which are directly correlated with increased risk of breast, colon, and prostate cancers. Chronic treatment (1 pM/L for 20 cycles) of MCF-10A cells with PhIP induces anchorage-independent cell growth and reduces cellular dependence on growth factors. It increases wild-type H-Ras gene and protein expression, which activates ERK signaling, MMP-2 and MMP-9 protein expression, and NOX1-driven production of reactive oxygen species (ROS) in vitro. In vivo, PhIP pre-treatment of MCF-10A cells increases tumor formation in a murine breast cancer xenograft model. In a CYP1A2 humanized rat model, PhIP induces formation of colon tumors with β-catenin gene mutations that hyperactivate the Wnt signaling pathway, mimicking the phenotype observed in human tumor isolates. In vivo administration of PhIP (400 ppm/week for 52 weeks) also increases the occurrence of atypical hyperplasias and carcinomas in the ventral prostate and seminal vesicles of rats.