Pharmacogenomics of phenolic antioxidant butylated hydroxyanisole (BHA) in the small intestine and liver of Nrf2 knockout and C57BL/6J mice

Purpose: The objective of this study was to investigate the pharmacogenomics and the spatial regulation of global gene expression profiles elicited by cancer chemopreventive agent butylated hydroxyanisole (BHA) in mouse small intestine and liver as well as to identify BHA-modulated nuclear factor-E2-related factor 2 (Nrf2)-dependent genes. Methods C57BL/6J (+/+; wildtype) and C57BL/6J/Nrf2(-/-; knockout) mice were administered a single 200 mg/kg oral dose of BHA or only vehicle. Both small intestine and liver were collected at 3 h after treatment and total RNA was extracted. Gene expression profiles were analyzed using 45,000 Affymetrix mouse genome 430 2.0 array and GeneSpring 7.2 software. Microarray results were validated by quantitative real-time reverse transcription-PCR analyses. Results: Clusters of genes that were either induced or suppressed more than two fold by BHA treatment compared with vehicle in C57BL/6J/Nrf2(-/-; knockout) and C57BL/6J Nrf2 (+/+; wildtype) mice genotypes were identified. Amongst these, in small intestine and liver, 1,490 and 493 genes respectively were identified as Nrf2-dependent and upregulated, and 1,090 and 824 genes respectively as Nrf2-dependent and downregulated. Based on their biological functions, these genes can be categorized into ubiquitination/proteolysis, apoptosis/cell cycle, electron transport, detoxification, cell growth/differentiation, transcription factors/interacting partners, kinases and phosphatases, transport, biosynthesis/metabolism, RNA/protein processing and nuclear assembly, and DNA replication genes. Phase II detoxification/antioxidant genes as well as novel molecular target genes, including putative interacting partners of Nrf2 such as nuclear corepressors and coactivators, were also identified as Nrf2-dependent genes. Conclusions: The identification of BHA-regulated and Nrf2-dependent genes not only provides potential novel insights into the gestalt biological effects of BHA on the pharmacogenomics and spatial regulation of global gene expression profiles in cancer chemoprevention, but also points to the pivotal role of Nrf2 in these biological processes.