Polyphyllin D exerts potent anti-tumour effects on Lewis cancer cells under hypoxic conditions

Paris polyphylla has been used to treat cancer in China for many years and components of the plant, such as polyphyllin D, may have potent antiproliferative effects in vitro. To investigate the potential antitumour effects of polyphyllin D on cancer cells under hypoxia, Lewis lung cancer cells and mouse tracheal epithelial cells were cultured with or without polyphyllin D under normoxic and hypoxic conditions. Proliferation and apoptosis of cells were assayed. Real-time reverse transcription-polymerase chain reaction was used to quantify the expression of hypoxia-inducible factor 1 alpha (HIF-1alpha) and vascular endothelial growth factor (VEGF) mRNA. Polyphyllin D decreased cell proliferation, increased apoptosis and inhibited expression of HIF-1alpha and VEGF mRNAs in Lewis cells. These effects were greater under hypoxic than normoxic conditions. Polyphyllin D did not show a cytotoxic effect in non-tumour cells (mouse skin fibroblasts and tracheal epithelial cells). These results suggest that polyphyllin D potentially has anticancer effects in vitro under hypoxia.