Human mitochondrial CYP2E1-mediated styrene metabolism increases oxidative stress and impairs antioxidant rescue in Caenorhabditis elegans.

Styrene is an environmental toxicant metabolized by cytochrome P450 2E1 (CYP2E1) to styrene oxide, a reactive intermediate product linked to oxidative stress. While the role of CYP2E1 in xenobiotic metabolism is well established, the influence of subcellular enzyme localization on styrene-induced toxicity remains unclear. This study used transgenic Caenorhabditis elegans (C. elegans) strains expressing CYP2E1 in different compartments, mitochondrial-derived (mtCYP2E1) and endoplasmic reticulum-derived (erCYP2E1), to investigate the impact of CYP2E1-mediated styrene metabolism on survival and oxidative stress. CYP2E1 containing C. elegans strains were also compared to a wildtype strain (N2) lacking CYP2E1. Styrene exposure significantly decreased survival across all strains. Antioxidant rescue assays revealed that Trolox and N-acetyl cysteine (NAC) improved survival in the N2 and erCYP2E1 C. elegans strains but not in mtCYP2E1, indicating a distinct oxidative stress mechanism in mitochondrial CYP2E1 metabolism. Fluorescent microscopy confirmed that ROS levels increased with styrene exposure, particularly in mtCYP2E1 C. elegans, where ROS levels were up to two-fold higher than in other strains. GC-MS analysis detected elevated styrene glycol production in styrene-exposed mtCYP2E1 C. elegans relative to N2 and erCYP2E1 strains. Given styrene oxide is a known cytotoxic intermediate, its accumulation in the mtCYP2E1 strain likely contributes to the observed oxidative stress and decreased survival. These findings suggest that CYP2E1 subcellular localization influences styrene metabolism and toxicity, with mitochondrial CYP2E1 potentially promoting higher oxidative stress and reduced detoxification efficiency. A better understanding of these mechanisms could provide insight into xenobiotic metabolism, environmental toxicology, and disease pathogenesis associated with CYP2E1-mediated oxidative stress.