Melatonin ameliorates 10‐hydroxycamptothecin‐induced oxidative stress and apoptosis via autophagy‐regulated p62/Keap1/Nrf2 pathway in mouse testicular cells

Abstract 10‐Hydroxycamptothecin (HCPT) is a widely used clinical anticancer drug but has a significant side effect profile. Melatonin has a beneficial impact on the chemotherapy of different cancer cells and reproductive processes, but the effect and underlying molecular mechanism of melatonin's involvement in the HCPT‐induced side effects in cells, especially in the testicular cells, are poorly understood. In this study, we found that melatonin therapy significantly restored HCPT‐induced testicular cell damage and did not affect the antitumor effect of HCPT. Further analysis found that melatonin therapy suppressed HCPT‐induced DNA damage associated with ataxia‐telangiectasia mutated‐ and Rad3‐related and CHK1 phosphorylation levels in the testis. Changes in apoptosis‐associated protein levels (Bax, Bcl‐2, p53, and Cleaved caspase‐3) and in reactive oxygen species‐associated proteins (Nrf2 and Keap1) and index (malondialdehyde and glutathione) suggested that melatonin treatment relieved HCPT‐induced cell apoptosis and oxidative damage, respectively. Mechanistically, melatonin‐activated autophagy proteins (ATG7, Beclin1, and LC3bII/I) may induce p62‐dependent autophagy to degrade Keap1, eliciting Nrf2 from Keap1‐Nrf2 interaction to promote antioxidant enzyme expression such as HO‐1, which would salvage HCPT‐induced ROS production and mitochondrial dysfunction. Collectively, this study reveals that melatonin therapy may protect testicular cells from HCPT‐induced damage via the activation of autophagy, which alleviates oxidative stress, mitochondrial dysfunction, and cell apoptosis.