2α,3α,24-Thrihydroxyurs-12-en-28-oicacid (TEOA), a pentacyclic triterpenoid, isolated from the roots of Actinidia eriantha, exhibits significant cytotoxicity against SW620, BGC-823, HepG-2, A549 and PC-3 cancer cells. In this study, we investigated the underlying molecular mechanism of the anticancer activity of TEOA in SW620 cells. We demonstrated that TEOA induced apoptosis through cleavage of caspase-9 and PARP in SW620 cells. In addition, evidence of TEOA-mediated autophagy included the induction of autophagolysosomes and activation of autophagic markers LC-3B and p62. Further analysis illustrated that TEOA promoted the phosphorylation of PERK and elF2α, followed by up-regulation of the downstream protein CHOP, suggesting the involvement of PERK/eIF2α/CHOP pathway and ER stress in TEOA-induced autophagy in SW620 cells. Meanwhile, TEOA-mediated PINK1, Parkin, ubiquitin and p62 activation revealed that TEOA induced specific autophagy-mitophagy in SW620 cells. Additionally, an antioxidant NAC attenuated the TEOA-induced mitophagy, indicating that TEOA triggers mitophagy via a ROS-dependent pathway. Collectively, our findings revealed a novel cellular mechanism of TEOA in the colon cancer cell line SW620, thus providing a molecular basis for developing TEOA into an anti-tumor candidate.
Keywords: Actinidia eriantha root; Autophagy; ER stress; Mitophagy; SW620; TEOA.