Antiproliferative activity of vitexin-2-O-xyloside and avenanthramides on CaCo-2 and HepG2 cancer cells occurs through apoptosis induction and reduction of pro-survival mechanisms

Purpose CaCo-2 colon cancer cells and HepG2 liver cancer cells represent two malignant cell lines, which show a high resistance to apoptosis induced by the conventional anticancer drugs. Vitexin-2-O-xyloside (XVX) and avenanthramides (AVNs) are naturally occurring dietary agents from Beta vulgaris var. cicla L. and Avena sativa L., respectively. The aim of this work was to evaluate the antiproliferative effects and the reduction of the pro-survival mechanisms exerted by XVX and AVNs, used individually and in combination, in CaCo-2 and HepG2 cancer cells. Methods XVX and AVNs were isolated by liquid chromatography and characterized by HPLC-PDA-MS. The XVX and AVN antiproliferative effects were evaluated through sulforhodamine B method, while their pro-apoptotic effects through caspase activity assays. RTqPCR was used to investigate the modulation of the pro-survival factors baculoviral inhibitor of apoptosis repeat-containing 5 (BIRC5), hypoxia inducible factor 1 A (HIF1A), and vascular endothelial growth factor A (VEGFA). Cellular antioxidant activity (CAA) was investigated by means of DCFH-DA assay, whereas chemical antioxidant capacity was evaluated by the ORAC method. Results XVX and AVNs, both individually and in combination, inhibited the proliferation of CaCo-2 and HepG2 cancer cells, through activation of caspases 9, 8, and 3. XVX and AVNs downregulated the pro-survival genes BIRC5, HIF1A, and VEGFA. The CAA assay showed that AVNs exhibited strong antioxidant activity inside both CaCo-2 and HepG2 cells. Conclusions The antiproliferative activity of the XVX + AVNs mixture represents an innovative treatment, which is effective against two types of cancer cells characterized by high resistance to the conventional anticancer drugs.