| Abstract: | Sorafenib remains the standard systemic treatment for advanced human hepatocellular carcinoma (HCC). However, the low response rate, high recurrence, and high progression limit the therapeutic efficacy. Therefore, a combination therapy strategy was advanced to strengthen the antitumor effects of sorafenib. In the present study, we aimed to evaluate whether icaritin could enhance the inhibitory effects of sorafenib on HCC cells and clarify the underlying mechanism. The cell viability was evaluated via MTT assay, and the synergistic inhibitory effects of sorafenib and icaritin were verified by calculating the combination index (CI). Their combined effects on cell proliferation or apoptosis were investigated using colony formation assay and flow cytometry. Mitochondrial membrane potential (MMP) was detected by flow cytometric assay. The protein expressions associated with the apoptotic pathway were determined by Western blotting analysis. The data demonstrated that sorafenib and icaritin exerted synergistic inhibitory effects on cell viability (CI < 1). Icaritin enhanced the inhibitory effect of sorafenib on colony formation and sorafenib-induced apoptosis of HCC cells. We discovered a reduced level of antiapoptotic Bcl-2 and an elevated level of proapoptotic protein Bax when the cells were exposed to the combination. The effect of cleaved and activated PARP was also enhanced. Cleaved caspase-9 and cleaved caspase-3 were increased markedly in the combination group. Furthermore, the combination of icaritin and sorafenib significantly increased the loss of MMP compared with the single treatment group and induced the release of cytochrome c from the mitochondria to the cytosol. These findings indicated that icaritin could enhance sorafenib-induced cytotoxicity and trigger sorafenib-induced apoptosis through a mitochondria-dependent pathway. |
