Zanthoxylum avicennae extracts induce cell apoptosis through protein phosphatase 2A activation in HA22T human hepatocellular carcinoma cells and block tumor growth in xenografted nude mice.

The use of herbs as alternative cancer therapies has attracted a great deal of attention owing to their lower toxicity. Whether Zanthoxylum avicennae (Ying Bu Bo, YBB) induces liver cancer cell apoptosis remains unclear. In this study, we investigated the effect of YBB extracts (YBBEs) on HA22T human hepatocellular carcinoma cells in vitro and in an in vivo mouse xenograft model. HA22T cells were treated with different concentrations of YBBEs and analyzed with Western blot analysis, TUNEL, JC-1 staining and siRNA transfection assays. Additionally, the HA22T-implanted xenograft nude mice model was applied to confirm the cellular effects. YBBEs-induced apoptosis, up-regulated death receptor apoptotic pathway markers as well as mitochondrial proteins, and suppressed the survival proteins in a dose-dependent manner. Pro-survival Bcl-2 family proteins were inhibited and the pro-apoptotic ones were increased. Protein phosphatase 2A (PP2A) siRNA or okadaic acid reversed the YBBEs effects, confirming the role of PP2A in YBBEs-induced HA22T apoptosis. All our experimental evidence indicates that YBBEs significantly promote HA22T apoptosis and reduce tumor sizes in xenograft nude mice via PP2A in a dose-dependent manner.