Investigation of the anticancer and immunostimulatory effects of exopolysaccharides obtained from Lacticaseibacillus rhamnosus ACS5 strain in vitro

Recent studies have revealed the potential of exopolysaccharides (EPS) produced by lactic acid bacteria (LAB) in different fields. EPSs produced by lAB are seen as important sources for anti-tumor, antioxidant, and immuno-stimulating activities. It has been observed that drugs used in cancer treatment cause immunotoxicity in normal cell and trigger tumor development mechanisms. These observations have become the main target of many studies, such as the discovery of anti-tumor drugs with low side effects. In our study, the antiproliferative effect of L-EPS-ACS5 obtained from Lacticaseibacillus rhamnosus ACS5 strain isolated from Ayvalık Cunda Sepet Cheese, one of the traditional cheeses of Turkey, on human colon cancer (HT-29) cell line, was compared with healthy control line (L929). It was evaluated as time dependet and showed antiproliferative effect. This effect was also confirmed by colony formation analysis. Apoptotic changes were examined at the molecular level using qPCR and Western blot. These changes were also confirmed by observations at the nuclear and cellular morphology level using a fluorescent 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 macrophage cell line (RAW 264.7). As a result of phagocytic activity and NO production analyses, the increase in proliferative activity was not found to be significant between the control and treatment groups. However, L-EPS-ACS5 did not show immunotoxic/cytotoxic activity in macrophage cells. All these cellular and molecular evidences shows that L-EPS-ACS5 may be a good alternative to synthetic anti-cancer agents in anticancer agents in colorectal cancer.