Chemoprevention of Colorectal Carcinogenesis by Natural Anti-Inflammatory Agents

Accumulating epidemiological, clinical, and experimental evidence demonstrates that chronic inflammation plays a critical role in multistep oncogenesis. While long-term users of selective cycloxygenase (COX)-2 inhibitors (- coxibs) and non-steroidal anti-inflammatory drugs (NSAIDs) exert a reduced risk of development of certain types of cancer, including colorectal cancer (CRC), the adverse gastrointestinal and cardiovascular side effects associated with these drugs have limited their daily use for cancer chemoprevention. The role of various proinflammatory mediators during carcinogenesis and their promise as potential targets for chemoprevention of inflammation-associated carcinogenesis has been recently highlighted. A variety of chemopreventive phytochemicals and phytonutrients are able to alter or correct undesired cellular functions caused by abnormal pro-inflammatory signal transmissions that are mediated by NF-kappaB, etc. Modulation of cellular signaling involved in chronic inflammatory responses, induced by anti-inflammatory agents, hence provides a rational and practical strategy in molecular target-based cancer chemoprevention. This short review will focus on the role of chronic inflammation in colorectal oncogenesis and introduce dietary cancer chemopreventive agents with anti-inflammatory activity.