Abstract
This study investigated the anti-tumor properties of Lactobacillus delbrueckii, a probiotic bacterium, against HT-29 human colorectal cancer cells. The primary objective was to evaluate the effects of Lactobacillus delbrueckii supernatant on gene expression, cell viability, apoptosis, and cell cycle progression in HT-29 cells. In Gilan Province, Iran, a native strain of Lactobacillus delbrueckii was identified from the supernatant of local yogurt. After treating HT-29 cells with different doses of the supernatant, the MTT test was used to calculate the IC50 value 24 hours later. Annexin V/PI staining and flow cytometry were used to evaluate the induction of apoptosis, and real-time PCR was used to measure changes in gene expression. The results showed that the supernatant of Lactobacillus delbrueckii strongly and dose-dependently reduced the growth of HT-29 cells. In addition to causing apoptosis and stopping the cell cycle in the G0/G1 phase, the therapy also increased the number of Sub-G1 cells, which is a sign of cell death. According to gene expression study, anti-apoptotic genes (AKT, Bcl-2) were downregulated while pro-apoptotic genes (PTEN, p53, and Bax) were upregulated. Interestingly, the natural isolate outperformed a conventional strain in terms of anticancer efficacy. These results demonstrate Lactobacillus delbrueckii's potential as a colorectal cancer treatment.