Evaluation of Inhibitory Effects of heat-killed Lactobacillus casei and Lactobacillus paracasei on human chronic myelocytic leukemia K562 cell line: an in vitro study

Probiotics are defined as different microorganisms that may have positive effects on preventing or treatment of special pathologic conditions. Anti-cancer properties of these bacteria have been shown in few studies. The aim of this study was to evaluate anti-tumor effects of heat-killed L. casei and L. paracasei on K562 cell line (chronic myeloid leukemia). In this experimental study, bacteria were cultured in special medium at anaerobic condition, then, cells killed at temperature of 100°C. Killed cells were dried by lyophilization, finally were sterilized by autoclaving. Then, different concentrations of heat-killed bacteria (125, 250, 500, 1000 and 2000 μg/ml) were prepared separately. Anti-tumor properties of heat-killed bacteria were determined in vitro at 24, 48 and 72 h with MTT assay. Our result showed that heat-killed cells of L. casei and L. paracasei statistically (p˂0.05) have Anti-tumor properties in K562. In addition, Anti-tumor properties of heat-killed cells have direct relationship with concentration. Based on obtained results we conclude that the heat killed Lactobacillus can be used as a potential candidate for further studies on chronic myeloid leukemia treatmentces.