Establishment of knockdown of superoxide dismutase 2 and expression of CYP3A4 cell system to evaluate drug-induced cytotoxicity.

Drug-induced hepatotoxicity is a major problem in drug development, and oxidative stress is known as one of the causes. Superoxide dismutases (SODs) are important antioxidant enzymes against reactive oxygen species (ROS). Mitochondria are the major source of superoxide production, and SOD2 is mainly localized in mitochondria and, with other SODs, plays an important role in scavenging superoxide. In this study, we established SOD2-knockdown cells. An adenovirus vector with short hairpin RNA against rat SOD2 (AdSOD2-shRNA) was constructed, and infection of AdSOD2-shRNA to rat hepatic BRL3A cells resulted in significant decreases of SOD2 mRNA and protein by 60%, and SOD2 activity by 50% after 3 days infection. We previously constructed an adenovirus expressing cytochrome P450 3A4 (AdCYP3A4). Co-infection of AdSOD2-shRNA and AdCYP3A4 to BRL3A cells was carried out to evaluate the superoxide- and CYP3A4-mediated formation of active metabolites, and mitochondrial toxicity, ROS and superoxide radical production and lipid peroxidation were selected to assess the cell viability. Albendazole, carbamazepine, dapsone, flutamide, isoniazid, nifedipine, sulfamethoxazole, trazodone, troglitazone, and zidovudine demonstrated significant increases of SOD2- and CYP3A4-mediated cytotoxicity. In conclusion, we constructed a highly sensitive cell system to evaluate oxidative stress and CYP3A4 mediated cytotoxicity that could be useful in preclinical drug development.