Effects of Lactobacillus casei Culture Supernatant on Differentiation of K562 Cell Line

ABSTRACT            Background and objective: Considering the toxic side effects of chemotherapy in treatment of cancer, anticancer drugs of natural origin including probiotic Lactobacillus strains have recently attracted a lot of attention. Methods: After culturing chronic myeloid leukemia cell line K562 in 96-well plates, effects of different concentrations of culture supernatant from Lactobacillus casei on differentiation of the cells were investigated after 48 and 72 hours under an inverted microscope. Number of live cells and percentage of viable cells were determined by trypan blue exclusion test of cell viability. Cytotoxicity was assessed by MTT assay. Data analysis was performed by SPSS (version) 22 using one-way analysis of variance and Tukey's test at significance level of 0.05.           Results: Secondary metabolites from the probiotic bacteria L. casei induced cellular differentiation, exerted anti-cancer effects and inhibited growth in K562 cells. Apoptotic cell death was confirmed by MTT and DNA fragmentation assays in a way that increasing the dilution from 1.2 to 1.32 significantly increased the viability of cells (P=0.001). In addition, increasing the dilution significantly increased the number of live cells in the first 48 hours (P=0.001).         Conclusion: Culture supernatant of L. casei reduces the number of live cells, and induces apoptosis and monocytic differentiation in K562 cells in a dose- and time-dependent manner. Therefore, combined chemotherapy and differentiation therapy using such supernatants could be useful for treatment of cancer.         Keywords: Cell differentiation, K562 cell line, Probiotic, Lactobacillus casei.