Mechanism study of oleanolic acid derivative, K73-03, inducing cell apoptosis in hepatocellular carcinoma

Abstract

Oleanolic acid (3β-hydroxyolean-12-en-28-oic acid, OA) is a kind of pentacyclic triterpene, which widely distributes in nature. OA possesses a powerful anti-cancer effect; however, its low solubility limits its bioavailability and application. In this study, a new OA derivative, K73-03, was used to determine its effect on liver cancer cells and detailed molecular mechanisms. We found that K73-03 could significantly inhibit the cell viability, migration and colony formation of SMMC-7721 and HepG2 cells in a dose-dependent manner, having a stronger effect on HepG2 cells. Excess ROS was produced when treated with K73-03 compared with the control group. After adding a reactive oxygen scavenger, N-acetyl-L-cysteine (NAC), the expression of ROS was downregulated. For mitochondrial dysfunction, K73-03 could reduce Mitochondrial membrane potential (∆Ψm) and inhibit cell respiration. In mechanism studies, the ratio of Bax/Bcl-2 and the expressions of cleaved-caspase9 and cleaved-caspase3 in HepG2 cells were upregulated after K73-03 treatment, while the ratio of LC3B-II/I and the expression of Beclin1 were also increased. The protein expressions of p-JAK2, p-STAT3, COX-2, p65 and p-65 in K73-03 treated HepG2 cells were downregulated and the nuclear translocation of p65 was inhibited. In our study, K73-03 may lead to the disorder of mitochondria in HepG2 cells, leading to excessive ROS production and apoptosis in cells. Meanwhile, K73-03 could induce cell apoptosis by inhibiting JAK2/STAT3 pathway and NF-κB/P65 pathway.