cytotoxic effect of immunotoxin containing the truncated form of pseudomonas exotoxin cell lines

objective: immunotoxins (its) have been developed for the treatment of cancer, and comprise of antibodies linked to toxins. also vascular endothelial growth factor (vegf) plays a key role in tumor angiogenesis, and the blockade of vegf receptor-2 (vegfr2) inhibits angiogenesis and tumor growth. the aim of this study was to produce anti-vegfr2/rpe (pseudomonas exotoxin) 38 it to test its cytotoxic activity and mechanism of action. materials and methods: in this basic research and experimental study, at first, dna that encodes recombinant pe38 protein was inductively expressed in escherichia coli (e.coli) and purified by nickel-sepharose chromatography and further analyzed by western blot. then, for production of it, rpe38 was chemically conjugated to anti-vegfr2. the cytotoxicity response of it treatment was evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (mtt) test in human umbilical vein endothelial cell (huvec) and michigan cancer foundation-7 (mcf-7) (vegfr2+) cell lines. the mechanism of it cytotoxicity was observed by annexin v staining and flow cytometry. continuous variables were compared with the analysis of variance (anova; for all groups). p values less than 0.05 were considered statistically significant. results: sds-page showed 98% purity of rpe38 and it. in vitro dose-dependent cytotoxicity assay demonstrated that anti-vegfr2/pe38 is toxic to vegfr2-positive cells. it treatment significantly inhibited proliferation of huvec and mcf-7 in a vegfr2-specific manner as compared with the control groups (p<0.05). flow cytometry showed that the mechanism of it induced cell death is mediated by apoptosis. conclusion: it treatment also caused remarkable synergistic cytotoxicity characterized by decreased cell viability, and an increased apoptotic index by both anti-vegfr2 and pe38. thus these results raise the possibility of using anti-vegfr2/pe38 it for cancer therapy because nearly all tumors induce local angiogenesis with high vegfr expression.