Dose-Dependent Cytotoxic Effects of Lactobacillus acidophilus, L. casei, and L. fermentum Probiotics Supernatants On the MCF-7 Breast Cancer Cell Line

Abstract

Breast cancer is a leading cause of cancer deaths in women worldwide. Although traditional therapies, such as chemotherapy and radiation, are effective, their side effects underscore the need for alternative treatments. Probiotic lactic acid bacteria (LAB), known for their health benefits and antibacterial properties, have shown potential as anticancer agents. The present study aims to examine the dose-dependent cytotoxic effects of metabolites derived from three LAB strains (Lactobacillus acidophilus, Lactobacillus fermentum, and Lactobacillus casei) on the MCF-7 breast cancer cell line. Lactic acid bacteria (LAB) strains were cultured in MRS broth, and their supernatants were obtained using centrifugation and filtration. The MTT assay was used to evaluate the cytotoxicity of the supernatants against cancer cells at concentrations of 0, 5, 10, and 20 µg/mL. Statistical analysis was conducted using Tukey's test and two-way ANOVA, and p < 0.05 was used to define significance. All LAB supernatants demonstrated substantial concentration-dependent cytotoxicity. Lactobacillus acidophilus exhibited the highest cytotoxicity, with an IC50 of 4.91 µg/mL, followed by L. casei (IC50 = 10.6 µg/mL) and L. fermentum (IC50 = 14.5 µg/mL). In contrast, at a concentration of 20 µg/mL, cell viability was measured at 9.37%, 31.25%, and 25.00% for L. acidophilus, L. fermentum, and L. casei, respectively. Marked variations were observed across the strains at elevated concentrations (10 and 20 µg/mL). These results indicate that LAB supernatants, particularly those from L. acidophilus, have potential as natural cytotoxic agents against breast cancer cells. These findings warrant further investigation of LAB-derived metabolites in cancer treatment.