Lopinavir/ritonavir induces hepatotoxicity in HepG2 cells through inhibition of the Nrf2 pathway, resulting in oxidative stress, endoplasmic reticulum stress, and cell cycle arrest.

Lopinavir/ritonavir (LPV/r), a clinically used protease inhibitor for treating human immunodeficiency virus, is associated with liver injury. In this study, we demonstrated that LPV/r significantly suppressed HepG2 cell viability and increased the secretion of ALT, AST and LDH in the cell supernatant. Flow cytometry analysis revealed that LPV/r induced cell cycle arrest at the G0/G1 phase and triggered apoptosis in HepG2 cells. Furthermore, LPV/r significantly induced oxidative stress and endoplasmic reticulum (ER) stress, evidenced by elevated intracellular reactive oxygen species (ROS) levels, ER vesicular dilation, and alterations in the expression of related proteins. Additionally, LPV/r markedly increased the expression of apoptosis-related proteins. Mechanistically, activation of Nrf2 with tBHQ or overexpression of Nrf2 protein can effectively reverse the suppression of Nrf2/HO-1 expression by LPV/r, thereby reducing ROS accumulation and alleviating LPV/r-induced hepatocyte injury. Collectively, our findings demonstrate that LPV/r suppresses Nrf2 and HO-1 protein, promotes ROS accumulation, which induces oxidative stress and ER stress, ultimately leading to cell apoptosis and G0/G1 phase cell cycle arrest. This research provides novel mechanistic insights into the hepatotoxic effects of LPV/r.