A non-immunotoxic exopolysaccharide with anticancer effect in colorectal cancer isolated from Lacticaseibacillus rhamnosus ACS5 strain

Abstract

Recent studies demonstrated the potential of exopolysaccharides (EPS) produced by LAB (lactic acid bacteria), to be used in different fields. In our study, L-EPS-ACS5 from Lacticaseibacillus rhamnosus ACS5 strain isolated from Ayvalık Cunda Sepet Cheese, one of the traditional cheeses of Turkey, showed antiproliferative effect in a time-dependent manner in human colon cancer (HT-29) cell line compared to healthy control line (L929). This effect was also confirmed by colony formation analysis. Apoptotic changes were investigated at molecular level using qPCR, Western blot and it was determined that the relevant L-EPS induced apoptosis by increasing Bax, Caspase 3, and 9 expression while reducing the Bcl-2 expression. These changes were confirmed by observations done at nuclear and cellular morphology level using a fluorescence microscope (Hoescht 33258) and TEM. In addition, the immunostimulatory activity of the relevant L-EPS was evaluated in terms of proliferation, phagocytosis ability and nitric oxide (NO) production parameters in the RAW 264.7 macrophage cell line. The increase in proliferative activity was not significant, and in parallel with these results, the differences in the control and application groups as a result of 'phagocytic activity and NO production analyzes' were also not significant. However, L-EPS-ACS5 did not show immunotoxic/cytotoxic activity in macrophage cells (% viability >70). All these cellular and molecular evidences indicate that L-EPS-ACS5 may be a good alternative to synthetic anti-cancer agents with its anticancer effect and non-immunotoxic properties in colorectal cancer.