Cytotoxic properties of DAB486EGF and DAB389EGF, epidermal growth factor (EGF) receptor-targeted fusion toxins

• Published in: The Journal of biological chemistry Vol. 266; no. 31; pp. 21118 - 21124
• Main Authors: Shaw, J.P., Akiyoshi, D.E., Arrigo, D.A., Rhoad, A.E., Sullivan, B., Thomas, J., Genbauffe, F.S., Bacha, P., Nichols, J.C.
• Format: Journal Article
• Language: English
• Published: Bethesda, MD Elsevier Inc 05-11-1991; American Society for Biochemistry and Molecular Biology
• Subjects: Adenosine Diphosphate Ribose - metabolism; Biological and medical sciences; Cell Death - drug effects; Cell receptors; Cell structures and functions; Diphtheria Toxin - chemistry; Epidermal Growth Factor - chemistry; ErbB Receptors - metabolism; Escherichia coli - genetics; Fundamental and applied biological sciences. Psychology; Genetic Engineering; Hormone receptors. Growth factor receptors. Cytokine receptors. Prostaglandin receptors; Humans; In Vitro Techniques; Molecular and cellular biology; Peptide Elongation Factor 2; Peptide Elongation Factors - metabolism; Plasmids; Recombinant Fusion Proteins - metabolism; Recombinant Fusion Proteins - toxicity; Human; Toxin; Cytotoxicity; Tumor; Growth factor; Biological receptor
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(18)54828-6

Elevated expression of the receptor for epidermal growth factor (EGF) is a characteristic of several malignancies including those of the breast, bladder, prostate, lung, and neuroglia. To therapeutically target the cytotoxic action of diphtheria toxin to EGF receptor-expressing tumor cells, we have constructed a hybrid gene in which the sequences for the binding domain of diphtheria toxin have been replaced by those for human EGF. The resulting fusion toxins, DAB486EGF and DAB389EGF, bind specifically to the EGF receptor and inhibit protein synthesis in a variety of EGF receptor expressing human tumor cell lines with an IC50 as low as 0.1 pM. Comparisons of DAB486EGF and DAB389EGF showed that DAB389EGF was consistently 10- to 100-fold more cytotoxic than DAB486EGF. Like diphtheria toxin, the cytotoxic action of DAB389EGF results from ADP-ribosylation of elongation factor-2 and is sensitive to the action of chloroquine. Studies of the kinetics of cellular intoxication showed that a 15-min exposure of EGF receptor-expressing A431 cells to DAB389EGF results in complete protein synthesis inhibition within 4 h. Furthermore, inhibition of protein synthesis results in elimination of human tumor cell colonies. These findings show that DAB389EGF is a potential therapeutic agent for a wide variety of EGF receptor-expressing solid tumors.