Probiotic lactic acid bacteria are live microorganisms that provide health benefits when administered in adequate amounts and may exhibit antiproliferative effects on various cancer cell lines, including colon cancer. This study investigates the cytotoxic effects of three Lactobacillus strains - Limosilactobacillus (L.) reuteri VA 102, Ligilactobacillus (L.) animalis VA 105, and Limosilactobacillus (L.) reuteri KCTC 3594 (ATCC 23272) - on mouse colon carcinoma cells (CT-26). Live cells, heat-killed cells, and cell-free supernatant (CFS) of Lactobacillus sp. were prepared and used to treat CT-26 cells at different concentrations. The cytotoxic effect was assessed using the MTT assay. The results indicated that the CFS of all strains significantly reduced the viability of CT-26 cells in a dose-dependent manner, with the VA 102 strain showing the most pronounced effect. Heat-killed cells of L. reuteri VA 102 and L. reuteri KCTC 3594 (ATCC 23272) also reduced cell viability. These findings suggest the potential anticancer properties of these Lactobacillus strains and indicate that CFS and heat-killed cells may offer a safer and more effective alternative to live bacteria for therapeutic applications. Our study contributes to the understanding of the potential of Lactobacillus strains, particularly L. reuteri VA 102, L. reuteri KCTC 3594 (ATCC 23272), and L. animalis VA 105, as possible candidates for cancer treatment and control.

INTRODUCTION
MATERIALS AND METHODS
    Cell culture
    Bacterial strain and culture medium
    Preparation of live cells, heat-killed cells, and cellfreesupernatant of Lactobacillus
    Assessment of cell proliferation using MTT assay
    Statistical analysis
RESULTS
    Cell-free supernatant of Lactobacillus sp. reduced theviability of CT-26 cells in a dose-dependent manner
    Effect of heat-killed Lactobacillus sp. cells on CT-26cell viability
    Effect of Lactobacillus sp. live cells on CT-26 cellviability
DISCUSSION
ACKNOWLEDGEMENTS
CONFLICT OF INTEREST STATEMENT
REFERENCES

• Ched Nicole Turbela Aguilar(Institute of Animal Medicine, College of Veterinary Medicine, Gyeongsang National University, Jinju 52828, Korea)
• Tran Xuan Ngoc Huy(Institute of Animal Medicine, College of Veterinary Medicine, Gyeongsang National University, Jinju 52828, Korea)
• Trang Thi Nguyen(Institute of Animal Medicine, College of Veterinary Medicine, Gyeongsang National University, Jinju 52828, Korea)
• Said Abdi Salad(Institute of Animal Medicine, College of Veterinary Medicine, Gyeongsang National University, Jinju 52828, Korea)
• Chaerim Park(V1bio Inc., B-1605, 167, Songpa-daero, Sonpa-gu, Seoul 05855, Korea)
• Hee Chol Kang(V1bio Inc., B-1605, 167, Songpa-daero, Sonpa-gu, Seoul 05855, Korea)
• Il-Hwan Kim(V1bio Inc., B-1605, 167, Songpa-daero, Sonpa-gu, Seoul 05855, Korea)
• Suk Kim(Institute of Animal Medicine, College of Veterinary Medicine, Gyeongsang National University, Jinju 52828, Korea) Corresponding author