Short communication: Antiproliferative effect of 8 different Lactobacillus strains on K562 cells.

Some strains of Lactobacillus genus have antiproliferative activities against cancer cells. However, until now, the exact effector molecules of Lactobacillus strains with anticancer activity have not been identified. The aim of the present study was to explore which fraction of the Lactobacillus cells exerts the highest antiproliferative effect. For this purpose, the heat-killed bacterial cells, bacterial cell wall extract, and genomic DNA of 8 Lactobacillus strains were prepared to assess their antiproliferative activities against human myeloid leukemia cell lines K562. The heat-killed bacterial cells of the 8 lactobacilli strains exerted antiproliferative effect on K562 cells, and the inhibition rates exerted by the heat-killed bacterial cells of the strains G15AL, M5AL, SB31AL, SB5AL, and T3AL were significantly higher than those exerted by the cell walls and genomic DNA of the strains. The bacterial DNA of G15AL exerted higher antiproliferative effect on K562 cells. The exact effector molecules and the effect mechanism of the strains should be further explored for the application of these strains as probiotic strains or bioactive probiotic molecules.