Arctigenin Suppresses Melanoma via Mitophagy Activation In vitro and Enhances Dacarbazine Sensitivity In vivo

Objective: This study aimed to investigate the effect and mechanism of arctigenin (ARG) on the sensitization of dacarbazine (DTIC) via the regulation of mitophagy. Methods: In vitro experiments were conducted to explore the effects of ARG on the biologi-cal behavior of melanoma cells, mitochondrial autophagy mediated by PINK1/Parkin, and the role of reactive oxygen species (ROS)-mitochondrial autophagy in the regulation of the biological behavior of melanoma cells by an ROS quenching agent, a mitochondrial autoph-agy inhibitor, and an activator. The effects of ARG and dacarbazine in nude mice were as-sessed. Results: CCK8 assays revealed that ARG inhibited the proliferation of the human melanoma cell lines A375 and SK-MEL-2. The observation of submicroscopic structures demonstrated mitochondrial damage. Flow cytometry further verified that ARG induced apoptosis. West-ern blot analysis revealed that the protein expression levels of cleaved caspase 3 and Bax in-creased, whereas that of Bcl-2 decreased. In addition, ARG increased ROS levels. LC3II/I, PINK1, and Parkin were increased. ARG-induced apoptosis was related to increased mito-chondrial oxidative stress and promoted the occurrence of mitochondrial autophagy. After the addition of the autophagy inhibitor Mdivi-1 or the ROS quencher N-acetylcysteine (NAC), the antiproliferative effect of ARG was markedly attenuated. The expression levels of PINK1, Parkin, LC3II/I, cleaved caspase 3, and Bax were increased, whereas that of Bcl-2 was decreased. The formation of mitochondrial autophagosomes was observed by transmis-sion electron microscopy. ARG inhibited the proliferation and induced the apoptosis of mel-anoma cells in vivo. Conclusion: Autophagy-mediated cell apoptosis was activated through the PINK1/Parkin pathway by ARG, effectively inhibiting the proliferation of human melanoma cells.