MiR-766-3p and miR-671-5p attenuate aristolochic acid-induced hepatotoxicity by directly targeting the key bioactivating enzyme NQO1.

Aristolochic acid (AA) as an emerging contaminant in herbal medicines or crops has been well-recognized for causing nephropathy since 1990s. Over the last decade, mounting evidence has linked AA to liver injury; however, the underlying mechanism is poorly elucidated. MicroRNAs respond to environmental stress and mediate multiple biological processes, thus showing biomarker potentials prognostically or diagnostically. In the present study, we investigated the role of miRNAs in AA-induced hepatotoxicity, specifically in regulating NQO1, the key enzyme responsible for AA bioactivation. In silico analysis showed that hsa-miR-766-3p and hsa-miR-671-5p were significantly associated with AAI exposure as well as NQO1 induction. A 28-day rat experiment of 20 mg/kg AA exposure demonstrated a 3-fold increase of NQO1 and an almost 50 % decrease of the homologous miR-671 that were accompanied with liver injury, which was consistent with in silico prediction. Further mechanistic investigation using Huh7 cells with IC50 of AAI at 146.5 µM showed both hsa-miR-766-3p and hsa-miR-671-5p were able to directly bind to and down-regulate NQO1 basal expression. In addition, both miRNAs were shown to suppress AAI-induced NQO1 upregulation in Huh7 cells at a cytotoxic concentration of 70 μM, and consequently alleviate AAI-induced cellular effects, including cytotoxicity and oxidative stress. Together, these data illustrate that miR-766-3p and miR-671-5p attenuate AAI-induced hepatotoxicity, and thus have monitoring and diagnostic potentials.