Celastrus orbiculatus Thunb. extract targeting DJ-1 inhibits non-small cell lung cancer invasion and metastasis through mitochondrial-induced ROS accumulation

Abstract

Ethnopharmacological relevanceCelastrus orbiculatus Thunb. is an ancient traditional Chinese herb with a long history of medicinal use. The ethyl acetate extract of Celastrus orbiculatus Thunb. (COE) has been shown to have anti-tumor effects in various preclinical studies. However, the anti-invasive and metastatic efficacy of COE in non-small cell lung cancer (NSCLC) and the mechanism by which COE regulates cellular oxidation levels are yet to be elucidated. AimTo study the anti-dissemination effect of COE on NSCLC and to elucidate the molecular mechanism of COE in regulating cellular oxidation levels and its effect on lung cancer invasion and metastasis. MethodsCCK-8 assay was used to detect the toxic effects of COE on NSCLC. Transwell assay and high-content imaging was used to detect the Motility of NSCLC. Transmission electron microscopy and three-dimensional (3D) imaging of mitochondrial fluorescence were employed to detect the number and structure of mitochondria. JC-1 probe was used to detect the level of mitochondrial membrane potential. Firefly luciferase assay was used to detect the level of total intracellular ATP. MitoSox probe and DCFH-DA probe were applied to detect the level of reactive oxygen species (ROS) inside the mitochondria and the total intracellular ROS, respectively. Immunohistochemistry was used to detect protein expression in xenograft tumors. ResultsCOE inhibited motility and induced DJ-1 downregulation in NSCLC at low toxic concentrations, and the antiseptic effect of COE was reduced significantly after the overexpression of DJ-1. COE induced structural disruption of mitochondria in NSCLC and accumulation of superoxide compounds, decreased the volume of membrane potential depolarization, and impaired energy production, ultimately leading to a large accumulation of ROS at the cellular level. The antioxidant acetylcysteine (NAC) significantly reversed the antiseptic capacity of COE. In a xenograft tumor model, protein expression of DJ-1, E-cadherin, N-cadherin, and MMP-2 in COE group was significantly changed compared to the model group. ConclusionIn the present study, COE inhibited NSCLC invasion and metastasis and was associated with the downregulation of DJ-1 and elevated ROS. COE-mediated downregulation of DJ-1 may be the primary cause of mitochondrial structural and functional dysfunction in NSCLC, eventually leading to ROS accumulation.