Determination of lactic acid bacteria antiproliferative, antigenotoxic and antiinflammatory effects

Cancer became one of the most commonly encountered diseases of our days. In the clinical practice, there is increased interest into the studies that develop alternative methods for the prevention as well as the treatment of the cancer. Although probiotic cultures were demonstrated to be an alternative in the anticancer studies in the last years, mechanism of antiproliferative effects has not been clearly revealed yet. In the study, we used 6 lactic acid bacteria that were obtained from human (baby feces) bacterial cultures in the Gazi University, Faculty of Science, Department of Biology, Biotechnology Laboratory Culture Collection and that became prominent with their probiotic features in the previous studies. Antiproliferative effects of live cell, metabolite and exopolysaccharides (EPS) of the bacteria on HT-29 and Caco-2 cancer cell line consisted of colorectal adenocarcinoma cells were examined. In both cell lines, live cells were found to have a more efficient antiproliferative effect compared to metabolites and EPSs. Best antiproliferative effect was obtained from live cells of the Lactobacillus brevis LB63 strain (51% cell death) in HT-29 colon cancer cell line (p<0.05). Genotoxic and antigenotoxic effects of live cells, metabolites and EPSs of the strains on human lymphocytes were investigated using single-cell electrophoresis and the analyses were performed. Live cells, metabolites and EPSs of the strains were found not to show genotoxic effects. Although all samples showed antigenotoxic effects, best antigenotoxic effect was obtained from live cells of the LB63 strain (48% inhibition) (p<0.05). Anti-inflammatory effects of the strains that became prominent with their anti-proliferative and antigenotoxic effects (L. brevis, L. plantarum, L. rhamnosus) on HT-29 and Caco-2 cell lines were investigated. The effect of live cell, metabolite and EPSs on cytokine release was investigated by creating an inflammation environment with tumor necrosis factor-? (TNF-?) for IL-8 release in both cell lines. It was found that metabolites and EPSs were less efficient in the suppression of IL-8 release compared to live cells and that the effect was greater in HT-29 cell line. In the suppression of IL-8 in HT-29 cell line, best effect was shown by live cells of LB63 strain (from 557 pg/mL to 302 pg/mL). In the cells in which inflammatory environment was not created using TNF-?, best results of the stimulation of IL-10 release was again obtained from HT-29 cell line and live cells of LB63 strain (from 49 pg/mL to 85 pg/mL) (p<0.05). In the statistical analysis performed using the data available, a substantial correlation was found between antiproliferative-antigenotoxicity and antiproliferative-antiinflammatory activities of the strains (live cell, metabolite and EPS) (p<0.05). In this study, it was found that LB63 strain could be used as both antiproliferative and antiinflammatory agent. Furthermore, it was revealed that EPSs of the probiotic cultures could be a useful alternative of the probiotic cultures for the prevention of cancer due to their antiproliferative and antiinflammatory effects. Based on the results of in vitro studies, it will be possible to bring alternative probiotic agents that are protective or therapeutic against the cancer in the medication industry area.