Animal models of carcinogenesis in inflamed colorectum: potential use in chemoprevention study.

Inflammation is a risk factor for cancer development in several tissues. In the colorectum, inflammatory bowel disease (ulcerative colitis and Crohn's disease) is a longstanding inflammatory disease with increased risk for colorectal cancer (CRC). Several molecular events involving in chronic inflammatory process contribute to multi-stage carcinogenesis of CRC in the inflamed colon. They include alterations in production of reactive oxygen and nitrogen species, upregulation of pro-inflammatory cytokines and inflammatory enzymes, and intestinal immune system. In this short review, experimental animal models of inflammation-associated CRC are described. Also, some preclinical data on chemoprevention of inflammation-associated CRC by astaxanthin and a specific inhibitor of nitric oxide synthase using these inflammation-related CRC models is briefly introduced.