title: A dimeric angiogenin immunofusion protein mediates selective toxicity toward CD22+ tumor cells.
abstract: To improve selective cytotoxicity and pharmacokinetics of an anti-CD22 antibody single chain Fv (scFv)-ribonuclease fusion protein, a dimeric derivative was generated. Human angiogenin was fused via a (G4S)3 spacer peptide to the carboxy-terminal end of the stable dimeric anti-CD22 VL-VH zero-linker scFv MLT-7. The dimeric fusion protein and a monovalent counterpart were produced as soluble proteins in the periplasm of Escherichia coli. Comparative studies with homogeneously purified fusion proteins revealed that both constructs specifically bound to the target antigen and retained ribonucleolytic activity. However, they exhibited a markedly different capability for killing CD22+ tumor cells. The monomeric construct inhibited protein synthesis of target cells in a dose-dependent manner, but 50% inhibition (IC50) could be achieved only at the highest tested concentration (>350 nM). In contrast, the dimeric fusion protein efficiently killed CD22+ Raji and Daudi tumor cell lines with IC50 values of 74 nM and 118 nM, respectively. These results show that the therapeutic potential of scFv-ANG fusion proteins can be markedly enhanced by engineering dimeric derivatives.
authors.affiliation: University of Essen, Institute of Immunology, 45122 Essen, Germany. michaela.arndt@medizin.uni-essen.de
authors.forename: Michaela A E
authors.initials: MA
authors.lastname: Arndt
authors.forename: Jürgen
authors.initials: J
authors.lastname: Krauss
authors.forename: Bang K
authors.initials: BK
authors.lastname: Vu
authors.forename: Dianne L
authors.initials: DL
authors.lastname: Newton
authors.forename: Susanna M
authors.initials: SM
authors.lastname: Rybak
mesh_terms: D015703:Antigens, CD / Q000276:immunology; D000944:Antigens, Differentiation, B-Lymphocyte / Q000276:immunology; D000951:Antigens, Neoplasm / Q000276:immunology; D000970:Antineoplastic Agents / Q000633:toxicity*; D015815:Cell Adhesion Molecules / Q000037:antagonists & inhibitors* / Q000276:immunology; D019281:Dimerization; D006801:Humans; D020128:Inhibitory Concentration 50; D037102:Lectins / Q000037:antagonists & inhibitors* / Q000276:immunology; D014176:Protein Biosynthesis / Q000187:drug effects; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism / Q000633:toxicity*; D051918:Sialic Acid Binding Ig-like Lectin 2; D014407:Tumor Cells, Cultured
chemical_list: D015703:Antigens, CD; D000944:Antigens, Differentiation, B-Lymphocyte; D000951:Antigens, Neoplasm; D000970:Antineoplastic Agents; C497867:CD22 protein, human; D015815:Cell Adhesion Molecules; D037102:Lectins; C504236:MLT7-ANG fusion protein, recombinant; D011993:Recombinant Fusion Proteins; D051918:Sialic Acid Binding Ig-like Lectin 2