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Abstract
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.
Keywords: Colorectal cancer, lactobacillus acidophilus, lactobacillus casei, probiotic
Introduction
Probiotics refer to harmless microorganisms that could have nutritional advantages. They also provide health benefits, when administered in adequate amounts.1 Since 1953, numerous positive effects of probiotics on ulcerative colitis, diarrhea and ectopic eczema have been reported.2-5 A number of clinical studies have been performed on the ability of probiotic in the prevention, control and treatment of various cancers, especially the gastrointestinal tract.6,7 Due to the large quantitities of probiotic bacteria in the gut (1011 CFU/g of the intestinal content), probiotics seems to be one of the most interesting candidates for the treatment of colorectal cancer (CRC).8 Lactic acid bacteria (LAB) or the Lactobacilli bacteria are commonly used in the dairy industry. Some LAB strains, known as probiotics, theoretically stimulate the immune system, leading to the prevention of colorectal cancer.9 Considering these points, several studies were performed on the health benefits of milk fermented with Lactobacillus casei and L. acidophilus.10-12 The results of these studies indicate the positive effects of these probiotics on prevention of diarrhea caused by antibiotic treatment in...