Abstract
The use of ginsenosides in cancer therapy has been intensively investigated. The ginsenoside Rh4 (Rh4), a rare saponin obtained from Panax notoginseng, dissolves in water more readily than total saponins, making this compound easier to use in anti-cancer pharmaceutics. Here, we investigated the antiproliferative activity and mechanisms of Rh4 in colorectal cancer, both in vivo and in vitro. A colorectal cancer xenograft model showed that Rh4 significantly inhibited tumor growth with few side effects. CCK-8 assays, flow cytometric analysis, Western blotting and immunohistochemistry revealed that Rh4 effectively suppressed colorectal cancer cell proliferation via inducing G0/G1 phase arrest, caspase-dependent apoptosis and autophagic cell death but was not significantly cytotoxic to normal colon epithelial cells. Furthermore, apoptosis played a dominant role in Rh4-induced cell death, as the pan-caspase inhibitor Z-VAD-FMK blocked cell death to a greater extent than the autophagy inhibitor 3-methyladenine. Moreover, Rh4 increased reactive oxygen species (ROS) accumulation and subsequently activated the JNK-p53 pathway. An ROS scavenger and JNK and p53 inhibitors significantly attenuated Rh4-induced apoptosis and autophagy. Thus, the present study is the first to illustrate that Rh4 triggers apoptosis and autophagy via activating the ROS/JNK/p53 pathway in colorectal cancer cells, providing basic scientific evidence that Rh4 shows great potential as an anti-cancer agent.