Bufalin induces G2/M phase arrest and triggers autophagy via the TNF, JNK, BECN-1 and ATG8 pathway in human hepatoma cells.

Liver cancer is the fifth most common cause of cancer death worldwide. The study of more effective anti-hepatoma drugs is urgently required. Bufalin has been isolated from a traditional Chinese medicine and possesses less toxicity to normal cells. However, it has been found to inhibit growth of cancer cells. In this study, we aimed to investigate the efficacy and mechanism of bufalin in Huh7, Hep3B and HA22T human hepatoma cells. The three cell lines were treated with bufalin, the proliferation was detected by WST-1 assay and cell cycle was detected by flow cytometry analysis. The results showed that bufalin inhibited the proliferation of hepatoma cells and regulated the hepatoma cell death program in a dose- and time-dependent manner without typical features of apoptosis. RT-PCR arrays were used to investigate the autophagy transcriptional response triggered by bufalin and 13 genes were altered and further confirmed by real-time PCR. The translation levels of selected genes were examined by western blot analysis to reveal the bufalin-induced autophagy cascade. Bufalin synergized with the JNK pathway to induce autophagy of hepatoma cells and is closely associated with the upregulation of TNF, BECN-1, MAPK and ATG8, together with the downregulation of Bcl-2 and Bid. Our study provided a multi-angle evaluation system for anti-hepatoma pharmacology for pre-clinical drug investigation. In this case, bufalin was capable of inducing hepatoma cell autophagy, suggesting a potential regimen for single or combined chemotherapy to overcome hepatoma in clinical practice.