20(s)-ginsenoside Rh2 promotes TRAIL-induced apoptosis by upregulating DR5 in human hepatocellular carcinoma cells.

Tumor necrosis factor-related apoptosis-inducing ligand is a potential therapeutic anti-cancer drug with selective cytotoxicity in cancer cells. However, in multiple clinical trials, the therapeutic effect of TRAIL is limited owing to tumor resistance. The combination of small molecules or other drugs may represent a suitable strategy to overcome TRAIL resistance. This study found that 20(s)-ginsenoside Rh2 sensitized non-sensitive human hepatocellular carcinoma cells to TRAIL-induced apoptosis. The combination of TRAIL and Rh2 decreased cell viability and increased caspase cascade-induced apoptosis in several liver cancer cell lines. Moreover, we found that Rh2 reduced the apoptosis-related protein XIAP and Survivin, a negative regulator of the apoptosis pathway. At the same time, Rh2 can further enhance TRAIL-induced apoptosis by upregulating the death receptor 5, thereby significantly enhancing its anti-tumor effect. Furthermore, Rh2 enhanced the therapeutic efficacy of TRAIL in mouse xenograft models, suggesting that Rh2 also sensitizes TRAIL in vivo. Taken together, our study indicates that Rh2 may act as a sensitizer in combination with TRAIL to increase the efficacy of its anti-tumor activity.