Effects of probiotic Lactobacillus acidophilus and Lactobacillus casei on colorectal tumor cells activity (CaCo-2).

BACKGROUND The probiotic microorganisms are live normal flora that provide nutritional benefits. When probiotic administered in adequate amounts, they also confer a health benefit on the host. Different mechanisms of probiotic effects include the following: stimulating the immune system, modifying the composition of normal intestinal flora and preventing the carcinogenic activity of fecal enzymes. In this study, direct effects of probiotic lactobacilli on tumor cells were investigated. METHODS Supernatants and bacterial extracts of two standard Lactobacillus species (L. acidophilus and L. casei) were prepared and CaCo-2 cells were treated with them. Probiotic effects on cell proliferation, necrosis, apoptosis, migration and invasion were assessed. RESULTS The supernatants of Lactobacilli decreased cell proliferation and increased cell apoptosis, however, no significant effect on cell necrosis was reported. In contrast, Lactobacilli extract, reduced cell proliferation and increased cell apoptosis. Lactobacilli extract also led to cell necrosis. Furthermore, both supernatants and cell extracts of the probiotic agents resulted in decreased cells' migration and invasion. CONCLUSION In this study, it was shown that Lactobacilli probiotics useful effects are not confined to the enhancement of the immune system; however, they effectively suppress the malignant phenotypes of colorectal cancer cells.