Recombinant hybrid protein, Shiga toxin and granulocyte macrophage colony stimulating factor effectively induce apoptosis of colon cancer cells

Abstract

To investigate the selective cytotoxic effect of constructed hybrid protein on cells expressing granulocyte macrophage colony stimulating factor (GM-CSF) receptor. HepG2 (human hepatoma) and LS174T (colon carcinoma) were used in this study. The fused gene was induced with 0.02% of arabinose for 4 h and the expressed protein was detected by Western blotting. The chimeric protein expressed in E.coli was checked for its cytotoxic activity on these cells and apoptosis was measured by comet assay and nuclear staining. The chimeric protein was found to be cytotoxic to the colon cancer cell line expressing GM-CSFRs, but not to HepG2 lacking these receptors. Maximum activity was observed at the concentration of 40 ng/mL after 24 h incubation. The IC(50) was 20+/-3.5 ng/mL. Selective cytotoxic effect of the hybrid protein on the colon cancer cell line expressing GM-CSF receptors (GM-CSFRs) receptor and apoptosis can be observed in this cell line. The hybrid protein can be considered as a therapeutic agent.