Extensive studies have revealed that berberine, a small molecule derived from Coptidis rhizoma (Huanglian in Chinese) and many other plants, has strong anti-tumor properties. To better understand berberine-induced cell death and its underlying mechanisms in cancer, we examined autophagy and apoptosis in the human hepatic carcinoma cell lines HepG2 and MHCC97-L. The results of this study indicate that berberine can induce both autophagy and apoptosis in hepatocellular carcinoma cells. Berberine-induced cell death in human hepatic carcinoma cells was diminished in the presence of the cell death inhibitor 3-methyladenine, or following interference with the essential autophagy gene Atg5. Mechanistic studies showed that berberine may activate mitochondrial apoptosis in HepG2 and MHCC97-L cells by increasing Bax expression, the formation of permeable transition pores, cytochrome C release to cytosol, and subsequent activation of the caspases 3 and 9 execution pathway. Berberine may also induce autophagic cell death in HepG2 and MHCC97-L cells through activation of Beclin-1 and inhibition of the mTOR-signaling pathway by suppressing the activity of Akt and up-regulating P38 MAPK signaling. This is the first study to describe the role of Beclin-1 activation and mTOR inhibition in berberine-induced autophagic cell death. These results further demonstrate the potential of berberine as a therapeutic agent in the emerging list of cancer therapies with novel mechanisms.

BACKGROUND AND PURPOSEFangchinoline is a novel anti-tumour agent with little known of its cellular and molecular mechanisms of action. Here we have investigated the mode of cell death induced by fangchinoline and its underlying mechanism in two human hepatocellular carcinoma cell lines, HepG2 and PLC/PRF/5. EXPERIMENTAL APPROACHApoptosis and autophagy were monitored in fangchinoline-treated HepG2 and PLC/PRF/5 cells by histological methods. The signal transduction pathways involved in activation of autophagy were examined, using immunoblotting, real-time PCR and siRNA techniques. KEY RESULTSFangchinoline did not induce apoptosis in HepG2 and PLC/PRF/5 cells but triggered, dose-dependently, autophagy, an alternative mode of cell death which may contribute to fangchinoline's anti-tumour action. Nuclear translocation of p53 was involved in induction of autophagy by fangchinoline, followed by selective transactivation of the autophagy-related gene sestrin2 and initiation of the autophagic process. Signalling by the AMP-activated protein kinase was also involved as a downstream target of sestrin2 and induced mTOR-independent autophagic cell death in both cell lines. siRNA for Atg5 or pharmacological block of p53 abolished fangchinoline-induced autophagy and inhibition of autophagy switched cell death to apoptosis in these cells, suggesting that cell death is irreversible once autophagy is induced by fangchinoline. CONCLUSIONS AND IMPLICATIONSFangchinoline is a highly specific agent inducing autophagic cell death in hepatocellular carcinoma cells with a novel mechanism, which elucidates the potential of fangchinoline to potentiate programmed cell death in cancer cells.

BackgroundmicroRNAs have been shown to regulate the chemosensitivity of cancer cells. The aim of this study is to investigate the role and mechanism of mir-23a in enhancing the anti-tumor effect of topoisomerase 2A (TOP2A) poison etoposide in human hepatocellular carcinoma (HCC).MethodsThe anti-tumor effect of chemotherapeutic agents in HCC cells were examined in vitro and in vivo xenograft model. Expression of mRNA and miRNAs were determined by quantitative real-time PCR. Protein expression was analyzed by immunoblotting.ResultsOverexpression of mir-23a could significantly potentiate the in vitro and in vivo anti-tumor effect of etoposide; however, ectopic expression of miR-23a fails to sensitize HCC cells to 5-fluorouracil treatment, indicating the miR-23a-induced cancer cell hypersensitivity in chemotherapy is TOP2A-specific though miR-23a overexpression could not directly up-regulate TOP2A expression. Topoisomerase 1(TOP1) is down-regulated in miR-23a-overexpressed HCC cells. MiR-23a could directly bind to 3′untranslated region of TOP1 mRNA, and suppress the corresponding protein expression and inhibition of miR-23a further arguments the expression of TOP1. MiR-23a was up-regulated during DNA damage in cancer cells in line with the p53 expression. Up-regulation of p53 induces mir-23a expression, while suppression of p53 inhibits miR-23a in HCC cells.ConclusionOur study sheds light on the role of miR-23a as a potential target in regulating chemosensitivity of HCC cells.