The Study of Extracellular Protein Fractions of Probiotic Candidate Bacteria on Cancerous Cell Line

INTRODUCTION: Probiotics are live microorganisms, habituated in the human intestine, which have a beneficial effect on our health. In spite of many reports about the anticancer effect of these bacteria in in–vivo and in–vitro, their mechanisms of action are not completely understood. The goal of this study was to compare the extracellular fractions of Lactobacillus casei and L. paracasei on the anti proliferation and apoptosis induction in K562 cell line. MATERIALS AND METHODS: L. casei and L. paracasei were cultured in MRS broth medium. Then extracellular secretions were collected and after enrichment, analyzed by electrophoresis. Fractionation were determined by gel filtration chromatography using sephadex G100 column, and the anticancer properties were evaluated. RESULTS: The results of SDS–PAGE showed various molecular weight of fractionated proteins of L. casei and L. paracasei. Bioactivity assessment illustrated that anti proliferative effects on K562 cells is dose and time dependent and the cytotoxic effects was parallel with protein concentration and the increase of time from 36 to 72 hours. CONCLUSION: Regarding the cell cytotoxicity results, the fractionated extracellular proteins of L. casei and L. paracasei have significant effects in inhibition of cancer cell proliferation. However, more study is needed to better elucidate the mechanisms of extracted proteins, and its effect on other human cancer cell lines.