Anti-cancer potential of Lactiplantibacillus plantarum NG28 through the induction of intrinsic apoptosis

Introduction: Probiotics and fermented foods have become the focal point of research across different scientific disciplines, with recent findings indicating that Lactiplantibacillus plantarum (L. plantarum) isolated from various origins, holds significant promise in combating numerous diseases, including cancer. Hence, our current study seeks to explore how the L. plantarum NG28 strain might counteract the growth of HT-29 colorectal adenocarcinoma cells, potentially contributing to anti-cancer strategies. Methods: The effect of the ethyl acetate extract of L. plantarum NG28 strain on HT-29 cells was evaluated in several ways. First, the cytotoxicity of HT-29 cells was determined by MTT assay. Additionally, the changes in cell morphology of HT-29 cells through DAPI staining and the induction of apoptosis using Annexin V-FITC/PI staining followed by flow cytometry were investigated. By using the RT-PCR and western blot techniques the expression of pro-apoptotic genes and proteins such as Bax, Caspase-9, and Caspase-3, as well as the anti-apoptotic gene Bcl-2 was examined. Results: The findings revealed that the ethyl acetate extract of L. plantarum NG28 strain had a significant impact on the viability of HT-29 colon cancer cells in a dose-dependent manner, in contrast to its minimal effect on HUVEC cells. DAPI staining revealed the noticeable DNA damage and condensation of treated HT-29 cells and the flow cytometry strengthened the occurrence of apoptosis in the treated HT-29 cells. RT-PCR and western blot techniques investigated the intrinsic apoptosis of HT-29 cells through the increased expression levels of pro-apoptotic genes / proteins and decreased expression levels of anti-apoptotic gene. Conclusion: The study demonstrated the anti-cancer activity of ethyl acetate extract of the L. plantarum NG28 strain against HT-29 colon cancer cells, primarily through the intrinsic apoptotic pathway. This suggests that L. plantarum NG28 strain could be used as a therapeutic tool in the inhibition and medication of colorectal cancer.