Laetiporus sulphureus mushroom extract strongly enhances proapoptotic effect of probiotics Bifidobacterium lactis on HCT-116 cells in a co-culture system

Abstract

Laetiporus sulphureus is an edible mushroom with significant medicinal potential due to its rich polyphenol composition. Complete activity of polyphenols in the colon depends on the probiotic bacteria which already demonstrated proapoptotic effects on colon cancer cells. Our study uses a simple HoxBan co-culture system in order to approximate real in vivo conditions. Present study examined for the first time the cytotoxic effect of L. sulphureus ethyl acetate extract (EALS) and Bifidobacterium animalis subsp. lactis (BAL) probiotic on colorectal (HCT-116) and healthy (MRC-5) cells. EALS, abundant in polyphenolics detected by HPLC, showed weak cytotoxic activity (MTT assay) on HCT-116 and MRC-5 cells. Strong cytotoxicity of BAL and BAL/EALS on HCT-116 cells (determined by trypan blue staining and flow cytometry) was due to induction of proapoptotic effects. External apoptotic pathway was activated via intensified expression of Caspase 8 and Caspase 3, detected by qPCR method. The results show that EALS strongly enhances the cytotoxic and proapoptotic effects of BAL on HCT-116 cells in the co-culture system. Directions for future research are suggested to ultimately provide the clarification whether the structural change of polyphenols caused by the activity of BAL, or the change in the metabolic activity of BAL by polyphenols, are responsible for exact mechanism of these treatments activity. Also, the consequences of direct contact of BAL and HCT-116 cells should be further examined in appropriate in vivo systems.