Statin-Induced Liver Injury Involves Cross-Talk between Cholesterol and Selenoprotein Biosynthetic Pathways

Abstract

Statins have become the mainstay of hypercholesterolemia treatment. Despite a seemingly clear rationale behind their use, the inhibition of HMG-CoA reductase, these compounds have been shown to elicit a variety of unanticipated and elusive effects and side effects in vivo. Among the most frequently noted side effects of statin treatment are elevations in liver enzymes. Here, we report our finding that atorvastatin, cerivastatin, and lovastatin at clinically common concentrations induce a selective, differential loss of selenoprotein expression in cultured human HepG2 hepatocytes. The primarily affected selenoprotein was glutathione peroxidase (GPx), whose biosynthesis, steady-state expression level, and catalytic activity were significantly reduced with 10 to 100 nM concentrations of the different compounds. Messenger RNA levels of GPx1 and GPx4 were unaffected by statin treatment, pointing at a post-transcriptional mechanism of selenoprotein suppression. Although statins at selenoprotein-modulatory doses were not cytotoxic by themselves, they induced a significantly increased sensitivity of the cells to peroxides, an effect that was largely reversible by supraphysiological concentrations of selenite. We conclude that statins inhibit the expression of inducible selenoproteins by preventing the mevalonate-dependent maturation of the single human selenocysteine-tRNA and may thereby evoke an increased vulnerability of the liver to secondary toxins. Selenoprotein modulation might constitute an important mechanism of statins to bring forth their clinical effects.