Design and Production of Recombinant TAT Protein Structure, Catalytic Domain of Diphtheria Toxin, and Evaluation of Its Effect on Cell Line

Background and Objectives: Cancer is one of the most deadly diseases in the present age and its conventional therapies have had low success. Toxin therapy of cancer is a new therapeutic approach, which has attracted the attention of pharmaceutical specialists. Diphtheria toxin consists of three functional, transducing, and binding domains, that the functional part inhibits protein synthesis and causes cell death. The purpose of this study was to produce the functional domain of the diphtheria toxin fused with a TAT penetrating peptide and to investigate its degree of lethality on cell line.   Methods: In this study, primer was designed for tat-diph gene and the gene construct containing the sequence of the functional chain of diphtheria toxin and the TAT peptide sequence, were amplified and cloned into prokaryotic expression vector pET-28a containing a sequence of histidine. After transferring into bacterial host (E. coli BL21 DE3), induction of expression was performed using IPTG, then, the resulting protein was purified and the protein expression was confirmed by anti-histidine antibody attached to horseradish peroxidase (HRP) using western blotting technique. In the next step, the lethality of the produced chimeric protein, was evaluated on MCF7 cell line by MTT assay. Data were analyzed by uni pirate and oligo 6 software.   Results: The results of MTT assay indicated that the TAT-Diph recombinant protein adjacent to the MCF7 cell line increased the rate of mortality of the cells.   Conclusion: The results of this study revealed that the recombinant protein with functional domain of diphtheria toxin and AT peptide could have lethal effect on MCF7 cell line.