title: Effect of trastuzumab interchain disulfide bond cleavage on Fcγ receptor binding and antibody-dependent tumour cell phagocytosis.
abstract: The Fc domain of human IgG1 binds to Fcγ receptors (FcγRs) to induce effector functions such as phagocytosis. There are four interchain disulfide bonds between the H and L chains. In this study, the disulfide bonds within the IgG1 trastuzumab (TRA), which is specific for HER2, were cleaved by mild S-sulfonation or by mild reduction followed by S-alkylation with three different reagents. The cleavage did not change the binding activities of TRA to HER2-bearing SK-BR-3 cells. The binding activities of TRA to FcγRIIA and FcγRIIB were greatly enhanced by modification with mild reduction and S-alkylation with ICH2CONH2 or N-(4-aminophenyl) maleimide, while the binding activities of TRA to FcγRI and FcγRIIIA were decreased by any of the four modifications. However, the interchain disulfide bond cleavage by the different modifications did not change the antibody-dependent cell-mediated phagocytosis (ADCP) of SK-BR-3 cells by activated THP-1 cells. The order of FcγR expression levels on the THP-1 cells was FcγRII > FcγRI > FcγRIII and ADCP was inhibited by blocking antibodies against FcγRI and FcγRII. These results imply that the effect of the interchain disulfide bond cleavage on FcγRs binding and ADCP is dependent on modifications of the cysteine residues and the FcγR isotypes.
authors.affiliation: Faculty of Pharmaceutical Sciences, Tokyo University of Science, Noda, Chiba 278-8510, Japan and Teijin Pharma Limited, 4-3-2 Asahigaoka, Hino-shi, Tokyo 191-8512, Japan mam.suzuki@teijin.co.jp.
authors.forename: Mami
authors.initials: M
authors.lastname: Suzuki
authors.affiliation: Faculty of Pharmaceutical Sciences, Tokyo University of Science, Noda, Chiba 278-8510, Japan and.
authors.forename: Ayaka
authors.initials: A
authors.lastname: Yamanoi
authors.affiliation: Faculty of Pharmaceutical Sciences, Tokyo University of Science, Noda, Chiba 278-8510, Japan and.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Machino
authors.affiliation: Faculty of Pharmaceutical Sciences, Tokyo University of Science, Noda, Chiba 278-8510, Japan and.
authors.forename: Michiko
authors.initials: M
authors.lastname: Ootsubo
authors.affiliation: Faculty of Pharmaceutical Sciences, Tokyo University of Science, Noda, Chiba 278-8510, Japan and.
authors.forename: Ken-ichi
authors.initials: K
authors.lastname: Izawa
authors.affiliation: Faculty of Pharmaceutical Sciences, Tokyo University of Science, Noda, Chiba 278-8510, Japan and.
authors.forename: Junya
authors.initials: J
authors.lastname: Kohroki
authors.affiliation: Faculty of Pharmaceutical Sciences, Tokyo University of Science, Noda, Chiba 278-8510, Japan and.
authors.forename: Yasuhiko
authors.initials: Y
authors.lastname: Masuho
mesh_terms: D000478:Alkylation; D000915:Antibody Affinity; D000920:Antibody-Dependent Cell Cytotoxicity; D000970:Antineoplastic Agents / Q000737:chemistry* / Q000276:immunology / Q000627:therapeutic use; D045744:Cell Line, Tumor; D057899:Cytophagocytosis; D006801:Humans; D007074:Immunoglobulin G / Q000737:chemistry / Q000276:immunology; D007460:Iodoacetamide / Q000737:chemistry; D008301:Maleimides / Q000737:chemistry; D009369:Neoplasms / Q000188:drug therapy / Q000276:immunology*; D017433:Protein Structure, Secondary; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism; D017452:Receptors, IgG / Q000276:immunology*; D000068878:Trastuzumab / Q000737:chemistry* / Q000276:immunology / Q000627:therapeutic use
chemical_list: D000970:Antineoplastic Agents; D007074:Immunoglobulin G; D007460:Iodoacetamide; D008301:Maleimides; D018719:Erb-b2 Receptor Tyrosine Kinases; D017452:Receptors, IgG; D000068878:Trastuzumab; C031489:N-(4-aminophenyl)maleimide; C508053:ERBB2 protein, human
keywords: Fcγ receptors; IgG1; interchain disulfide bonds; phagocytosis; trastuzumab