THE ROLE OF LACTOBACILLUS RHAMNOSUS GG AS A MODIFIER OF THE HUMAN BREAST CANCER CELLS PROLIFERATION AND APOPTOTIC PROGRAM

Abstract

Summary. Aim: to investigate the influence of human microbiota element Lactobacillus rhamnosus on the viability, proliferation and apoptosis of breast cancer (BC) cells with various degrees of malignancy in vitro. Objects and methods: human breast cancer cells of the MCF-7, T47D and MDA-MB-231 lines, as well as live and pasteurized bacteria cells of Lactobacillus rhamnosus or their secreted metabolites, were used as research objects. The expression of proteins associated with the proliferation and apoptosis regulation in breast cancer cells was assessed by immunocytochemical analysis. Results: the direct interaction of Lactobacillus rhamnosus live cells and BC cells leads to the most significant effect on the viability and proliferation of malignant cells, compared to the action of their secreted metabolites (contactless cocultivation in the Insert system) or pasteurized microorganisms. Incubation of luminal-type breast cancer cells with Lactobacillus rhamnosus was accompanied by suppression of the proliferation marker Ki-67expression. Co-cultivation of T47D cells and Lactobacillus rhamnosus led to increased expression of both the pro-apoptotic proteins Bax and p21WAF1, as well as the anti-apoptotic protein Bcl-2. In MCF-7 cells lactobacilli increased the expression of p21WAF1, but did not affect the expression of Bcl-2. In MDA-MB-231 cells, which are characterized by the highest degree of malignancy, Lactobacillus rhamnosus caused only an increase in the anti-apoptotic marker Bcl-2 expression. Conclusions: in human ВС cells with various degrees of malignancy after their cultivation with Lactobacillus rhamnosus, various vector mechanisms of modification of the vital activity system of malignant cells by changing their proliferative activity and initiating their apoptotic program were revealed. Key words: microbiota, Lactobacillus, breast