A specific and potent immunotoxin composed of antibody ZME-018 and the plant toxin gelonin.

Abstract

Murine monoclonal antibody ZME-018 recognizes a 240 Kda glycoprotein present on the surface of most human melanoma cells and on over 80% of human biopsy specimens tested. Gelonin is a ribosome-inactivating plant toxin similar in nature and rivaling the activity of ricin A chain. ZME-018 was coupled to purified gelonin using the reagents SPDP and 2-iminothiolane. The ZME-gelonin conjugate was purified by S-300 Sephacryl and Blue Sepharose chromatography, removing unreacted gelonin and antibody, respectively. PAGE analysis showed that ZME was coupled to 1, 2, or 3 gelonin molecules. The ZME-gelonin conjugate was 10(6)-fold more active than gelonin itself in inhibiting the growth of log-phase human melanoma cells in culture. The immunoconjugate was not cytotoxic to antigen negative T-24 (human bladder carcinoma) cells. Treatment of melanoma cells with recombinant IFN-alpha or TNF substantially augmented the cytotoxicity of the immunoconjugate while treatment with IFN-gamma had a minor effect. Using the human tumor colony assay of melanoma cells obtained from fresh biopsy specimens, greater than 90% growth suppression was observed in 2 of 4 samples tested at a concentration of 250 ng/ml. In addition, 25% growth suppression was observed with a third sample tested, and no growth suppression was observed in 1 sample. Thus, clonogenic melanoma cells are sensitive in vitro to the cytotoxic activity of this immunotoxin at concentrations which we presume are pharmacologically relevant.

• Authors: M G Rosenblum, J L Murray, L Cheung, R Rifkin, S Salmon, R Bartholomew
• Journal: Molecular biotherapy (Mol Biother) Vol. 3 Issue 1 Pg. 6-13 (Mar 1991) ISSN: 0952-8172 [Print] United States
• PMID: 1906286 (Publication Type: Journal Article)

Chemical References

• Antibodies, Neoplasm
• Immunotoxins
• Interferon Type I
• Plant Proteins
• Protein Synthesis Inhibitors
• Ribosome Inactivating Proteins, Type 1
• Tumor Necrosis Factor-alpha
• GEL protein, Gelonium multiflorum
• Interferon-gamma

Topics

• Antibodies, Neoplasm
• Cytotoxicity, Immunologic
• Humans
• Immunotoxins (isolation & purification, pharmacology)
• Interferon Type I (pharmacology)
• Interferon-gamma (pharmacology)
• Melanoma (immunology)
• Plant Proteins (pharmacology)
• Protein Synthesis Inhibitors (pharmacology)
• Ribosome Inactivating Proteins, Type 1
• Tumor Necrosis Factor-alpha (pharmacology)
• Tumor Stem Cell Assay