title: Characterization of a chimeric monoclonal antibody against the insulin-like growth factor-I receptor.
abstract: The insulin-like growth factors (IGFs) signaling system has been shown to play important roles in neoplasia. The IGF receptor type 1 (IGF-IR) is overexpressed in many types of solid and hematopoietic malignancies, and there is substantial experimental and clinical evidence that targeting IGF-IR is a promising therapeutic strategy against cancer. It has been previously reported that a mouse monoclonal antibody (mAb), 4G11, blocked IGF-I binding to IGF-IR and downregulated the IGF-IR in MCF-7 cells. We cloned this antibody, constructed a human-mouse chimeric antibody, designated m590, and characterized it. The chimeric IgG1 m590 bound to cell-associated IGF-IR on NWT c43 stably transfected cells and MCF-7 breast cancer cells as efficiently as the parental murine antibody. Using purified IGF-IR extracellular domains, we found that both the chimeric m590 and the parental 4G11 antibodies bind to conformational epitopes on IGF-IR. Neither of these antibodies bound to the insulin receptor (IR) ectodomain. Furthermore, IgG1 m590 blocked the binding of IGF-I and IGF-II to IGF-IR, and inhibited both IGF-I and IGF-II induced phosphorylation of IGF-IR in MCF-7 cells. These results suggest that m590 could be an useful antibody in diagnosis and treatment of cancer, as well as a research tool.
authors.affiliation: Center for Cancer Research Nanobiology Program, CCR, NCI-Frederick, NIH, Frederick, MD, USA. zhangmy@hku.hk
authors.forename: Mei-Yun
authors.initials: MY
authors.lastname: Zhang
authors.forename: Yang
authors.initials: Y
authors.lastname: Feng
authors.forename: Yanping
authors.initials: Y
authors.lastname: Wang
authors.forename: Dimiter S
authors.initials: DS
authors.lastname: Dimitrov
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D000911:Antibodies, Monoclonal / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D001483:Base Sequence; D045744:Cell Line, Tumor; D006801:Humans; D007128:Immunoglobulin Fragments / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D051379:Mice; D008969:Molecular Sequence Data; D017526:Receptor, IGF Type 1 / Q000276:immunology* / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000276:immunology / Q000378:metabolism; D015398:Signal Transduction; D014162:Transfection
chemical_list: D000911:Antibodies, Monoclonal; D007128:Immunoglobulin Fragments; D011994:Recombinant Proteins; D007334:Insulin-Like Growth Factor I; D017526:Receptor, IGF Type 1