Modulation of the glucose metabolism pathways and expression of EMT-associated markers in breast cancer cells by exposure to Bifidobacterium animalis

The microbiota is an important element of the tumor microenvironment and is able to influence the biological properties of malignant cells, which determine their malignancy and sensitivity to anticancer therapy. To investigate the effect of the microbiota member Bifidobacterium animalis (B. animalis) on glucose metabolism, the expression of genes regulating these processes, ROS levels, and the expression of EMT-associated proteins in breast cancer (BC) cells of different molecular subtypes. BC cell lines: T47D, MCF-7, MDA-MB-231; prokaryotic cells: Bifidobacterium animalis subsp. lactis BB-12. Metabolic activity of BC cells was determined by biochemical methods. Expression levels of glucose transporters and key enzymes of glycolysis genes were assessed by real-time PCR. Viability of BC cells and ROS production were determined by flow cytometry. Expression of EMT-associated proteins was analyzed by immunocytochemical analysis. BC cells treated with B. animalis are characterized by a shift in the metabolic profile towards increased glycolysis, inhibition of proliferation and induction of changes in the redox state of cells. A statistically significant increase in glucose consumption and lactate production rate, lactate dehydrogenase activity was observed in B. animalis-treated BC cells of all three lines. The detected changes in mRNA expression of the glucose transporter genes GLUT1 and GLUT4 and the lactate dehydrogenase isoforms LDHA and LDHB confirm that B. animalis does not simply modulate individual metabolic or signaling pathways, but triggers a complex reprogramming of BC cells in a direction characteristic of their molecular subtype. In B. animalis-treated BC cells G6PD activity correlates with the level of ROS production in a feedback loop. The multidirectional influence of prokaryotic members of the microbiome was also revealed when studying the EMT-associated profile of breast cancer cells of different molecular subtypes: the expression of biomarkers differed depending on the initial dominance of epithelial or mesenchymal characteristics. The data support the concept that bifidobacteria can act as modulator of the tumor microenvironment and glycolytic activity of breast cancer cells.