Modulation of nuclear factor E2-related factor 2–mediated gene expression in mice liver and small intestine by cancer chemopreventive agent curcumin

Curcumin has been shown to prevent and inhibit carcinogen-induced tumorigenesis in different organs of rodent carcinogenesis models. Our objective is to study global gene expression profiles elicited by curcumin in mouse liver and small intestine as well as to identify curcumin-regulated nuclear factor E2-related factor 2 (Nrf2)-dependent genes. Wild-type C57BL/6J and Nrf2 knockout C57BL/6J/Nrf2(-/-) mice were given a single oral dose of curcumin at 1,000 mg/kg. Liver and small intestine were collected at 3 and 12 hours after treatments. Total RNA was extracted and analyzed using Affymetrix (Santa Clara, CA) mouse genome 430 array (45K) and GeneSpring 6.1 software (Silicon Genetics, Redwood City, CA). Genes that were induced or suppressed >2-fold by curcumin treatments compared with vehicle in wild-type mice but not in knockout mice were filtered using GeneSpring software and regarded as Nrf2-dependent genes. Among those well-defined genes, 822 (664 induced and 158 suppressed) and 222 (154 induced and 68 suppressed) were curcumin-regulated Nrf2-dependent genes identified in the liver and small intestine, respectively. Based on their biological functions, these genes can be classified into the category of ubiquitination and proteolysis, electron transport, detoxification, transport, apoptosis and cell cycle control, cell adhesion, kinase and phosphatase, and transcription factor. Many phase II detoxification/antioxidant enzyme genes, which are regulated by Nrf2, are among the identified genes. The identification of curcumin-regulated Nrf2-dependent genes not only provides potential novel insights into the biological effects of curcumin on global gene expression and chemoprevention but also points to the potential role of Nrf2 in these processes.