In vitro effects of crocin on the possible anticancer properties of Lactococcus lactis against colorectal adenocarcinoma cells

Probiotics have been suggested to contribute to cancer prevention through various mechanisms. Additionally, recent studies have established a connection between diet, microbiota, and overall health. In this respect, the current study aims to understand the impact of crocin on possible anti-cancer and antibacterial effects of Lactococcus lactis (L. lactis) in colorectal cancer cells and pathogenic bacteria. The study involved collecting cell-free supernatants (CFSs) from untreated bacteria as a control group and bacteria treated with crocin, and then examining their ability to prevent the growth of HCT-116 colon cancer cells. It was demonstrated that L. lactis, when treated with crocin, can effectively combat against various types of pathogenic bacteria and can survive in acidic conditions. Both CFS and cro-CFS exhibited a dose-dependent inhibition of HCT-116 cell growth but crocin-treated bacteria showed more significant effects. The half-maximal inhibitory concentration (IC50) for cell growth inhibition was 97.41 µL/mL in CSF group and 72.07 µL/mL in cro-CFS group. The results of flow cytometry tests confirmed the MTT assay findings, showing that cro-CFS group had a significantly higher rate of apoptosis compared to CFS of control group. The results obtained from qPCR also showed that the Caspase 9 and BAX genes were upregulated, and the BCL-2 expression level was reduced in cells treated with cro-CFS compared to the CFS group. Overall, these findings suggest that crocin may alter the composition of CFS from probiotics that are present in the gut, potentially impacting their ability to combat cancer.