Probiotic Lactobacillus Acidophilus and L. Casei Mix Sensitize Colorectal Tumoral Cells to 5-Fluorouracil-Induced Apoptosis

Abstract

To assess the potential of Lactobacillus acidophilus and Lactobacillus casei strains to increase the apoptosis of a colorectal cancer cell line in the presence of 5-fluorouracil (5-FU), LS513 colorectal cancer cells were treated for 48 h with increasing concentrations of these lactic acid bacteria (LAB) in the presence of 100 μ g/ml of 5-FU. In the presence of 10⁸ CFU/ml of live LAB, the apoptotic efficacy of the 5-FU increased by 40%, and the phenomenon was dose dependent. Moreover, irradiation-inactivated LAB caused the same level of induction, whereas microwave-inactivated LAB reduced the apoptotic capacity of the 5-FU. When cells were treated with a combination of live LAB and 5-FU, a faster activation of caspase-3 protein was observed, and the p21 protein seems to be downregulated. These results suggest that live L. acidophilus and L. casei are able to increase the apoptosis-induction capacity of 5-FU. The mechanisms of action are still not elucidated, and more research is needed to understand them. This is the first set of experiments demonstrating that some strains of LAB can enhance the apoptosis-induction capacity of the 5-FU. Based on these results, it is possible to speculate that LAB or probiotics could be used as an adjuvant treatment during anticancer chemotherapy.

ACKNOWLEDGMENTS

This research was supported by the Quebec Research Council in Fishing and Agri-Food (CORPAQ) of the Quebec ministry of Agriculture, Fishery and Food (MAPAQ) and by Bio-K Plus International Inc. through their “Volet Compétitivité des Entreprises” program. The authors are grateful to Bio-K Plus International Inc. for providing the lactobacilli probiotic preparation.

Notes

∗Cindy Baldwin and Mathieu Millette contributed equally to this article.

^†Daniel Oth is now a retired professor.