Anticancer potential of fermented milk with autochthonous lactic acid bacteria

The purpose of this study was to investigate the effect of fermented milk supernatants of autochthonous lactic acid bacteria, including Lactobacillus helveticus KMCH1 (ON561781), Lactococcus lactis KMCM3 (ON561782), and Lactiplantibacillus plantarum KMJC4 (ON615217), on human colon cancer (HT-29) and normal mouse fibroblast (L929) cells in vitro. Proteolytic activity, 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium bromide test, evaluation of apoptosis induction, and cell cycle arrest by flow cytometry were the assays performed in this study. The measurement of proteolytic activity of three types of fermented milk supernatant using an orthophthalaldehyde reagent showed that the fermented milk supernatant of L. helveticus KMCH1 included the highest proteolysis. Three types of fermented milk supernatant showed anticancer effects on HT-29 cell in a time- and concentration-based manner (at a concentration of 16 mg ml-1 for 72 h of incubation), while the effect of three types of supernatant on inhibition of L929 cell was 3%-10%. Besides, three types of supernatant inhibited HT-29 cell proliferation by inducing apoptosis and cell cycle arrest in the S phase. Autochthonous lactic acid bacteria strains were able to produce bioactive peptides with anticancer effects in fermented milk. Inhibition of HT-29 cell proliferation was dependent on peptide concentration.