Comparative study of cytotoxic effect of verotoxin1 on Vero and MCF-7 cells.

Verotoxins are subunit toxins, that involve in pathogenesis of Enterohemorrhagic Escherichia coli. Early studies of cytotoxicity on tumor cells indicate that verotoxin1 is effective in in vitro and laboratory animals. Because of specific receptors on studied tumor cells, verotoxin1 exerts selective cytotoxicity. The purpose of this study was to compare the cytotoxicity of verotoxin1 on vero and MCF-7 cell lines. Toxin production in five verotoxigenic straines was screened by verotoxin–producing Escherichia coli-reverse passive latex agglutination test (VTEC-RPLA kit, Oxoid, Co, Ltd) and after confirming verotoxin1 production from one of them,toxin purified by affinity chromatography. Then Vero and MCF-7 cells treated with serial dilutions of toxin, and viability and fragmentation of genome were studied. Our results indicated that MCF-7 cells was also susceptibile. The Lethal Dose 50% (LD 50%) for the treated cells was about 50 nanograms of toxin per milliliter. Evidences of apoptosis in the cells were studied by the fragmentation of DNA. Our results are in accordance with previous studies about cytotoxicity of verotoxin1 against human tumor cells and specially breast cancer lines. It indicates that verotoxin1 can be used as a potential selective cytotoxic factor against wide variety of human tumors.