title: Anti-epidermal growth factor receptor monoclonal antibody cetuximab inhibits EGFR/HER-2 heterodimerization and activation.
abstract: Human carcinomas frequently express one or more members of the epidermal growth factor receptor family. Two family members, epidermal growth factor receptor (EGFR) and c-erbB2/neu (HER2), homodimerize or heterodimerize upon activation with ligand and trigger potent mechanisms of cellular proliferation, differentiation and migration. In this study, we examined the effect of the anti-EGFR monoclonal antibody Erbitux (cetuximab) on human tumor cells expressing both EGFR and HER2. Investigation of the effect of cetuximab on the activation of EGFR-EGFR, EGFR-HER2 and HER2-HER2 homodimers and heterodimers was conducted using the NCI-N87 human gastric carcinoma cell line. Treatment of NCI-N87 cells with cetuximab completely inhibited formation of EGFR-EGFR homodimers and EGFR-HER2 heterodimers. Activation of HER2-HER2 homodimers was not appreciably stimulated by exogenous ligand and was not inhibited by cetuximab treatment. Furthermore, cetuximab inhibited EGF-induced EGFR and HER2 phosphorylation in CAL27, NCI-H226 and NCI-N87 cells. The activation of downstream signaling molecules such as AKT, MAPK and STAT-3 were also inhibited by cetuximab in these cells. To examine the effect of cetuximab on the growth of tumors in vivo, athymic mice bearing established NCI-N87 or CAL27 xenografts were treated with cetuximab (1 mg, i.p., q3d). The growth of NCI-N87 and CAL27 tumors was significantly inhibited with cetuximab therapy compared to the control groups (p<0.0001 in both cases). In the CAL27 xenograft model, tumor growth inhibition by cetuximab treatment was similar to that by cetuximab and trastuzumab combination treatment. Immunohistological analysis of cetuximab-treated tumors showed a decrease in EGFR-HER2 signaling and reduced tumor cell proliferation. These results suggest that cetuximab may be useful in the treatment of carcinomas co-expressing EGFR and HER2.
authors.affiliation: ImClone Systems Incorporated, New York, NY, USA.
authors.forename: Dipa
authors.initials: D
authors.lastname: Patel
authors.forename: Rajiv
authors.initials: R
authors.lastname: Bassi
authors.forename: Andrea
authors.initials: A
authors.lastname: Hooper
authors.forename: Marie
authors.initials: M
authors.lastname: Prewett
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Hicklin
authors.forename: Xiaoqiang
authors.initials: X
authors.lastname: Kang
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000627:therapeutic use*; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D000068818:Cetuximab; D019281:Dimerization; D066246:ErbB Receptors / Q000276:immunology*; D005434:Flow Cytometry; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D010766:Phosphorylation / Q000187:drug effects; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D015398:Signal Transduction / Q000187:drug effects; D013274:Stomach Neoplasms / Q000188:drug therapy* / Q000276:immunology / Q000378:metabolism; D014183:Transplantation, Heterologous; D014410:Tumor Stem Cell Assay
chemical_list: D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents; D000068818:Cetuximab; D066246:ErbB Receptors; D018719:Erb-b2 Receptor Tyrosine Kinases