title: Insulin-like growth factor receptor as a therapeutic target in head and neck cancer.
abstract: OBJECTIVE
  Insulin-like growth factor type I receptor (IGF-IR) plays critical roles in epithelial cancer cell development, proliferation, motility, and survival, and new therapeutic agents targeting IGF-IR are in development. Another receptor tyrosine kinase, the epidermal growth factor receptor (EGFR), is an established therapeutic target in head and neck cancer and IGF-IR/EGFR heterodimerization has been reported in other epithelial cancers. The present study was undertaken to determine the effects of anti-IGF-IR therapeutic targeting on cell signaling and cancer cell phenotypes in squamous cell carcinomas of the head and neck (SCCHN).
  
  
  METHODS
  The therapeutic efficacy of the human anti-IGF-IR antibody IMC-A12 alone and in combination with the EGFR blocking antibody cetuximab (C225) was tested in SCCHN cell lines and in tumor xenografts.
  
  
  RESULTS
  IGF-IR was overexpressed in human head and neck cancer cell lines and tumors. Pretreatment of serum-starved 183A or TU159 SCCHN cell lines with A12 (10 microg/mL) blocked IGF-stimulated activation of IGF-IR, insulin receptor substrate (IRS)-1 and IRS-2, mitogen-activated protein kinase, and phosphatidylinositol 3-kinase. A12 induced G(0)-G(1) cell cycle arrest and blocked cell growth, motility, and anchorage-independent growth. Stimulation of head and neck cancer cells with either IGF or EGF resulted in IGF-IR and EGFR heterodimerization, but only IGF caused activating phosphorylation of both receptors. Combined treatment with A12 and the EGFR blocking antibody C225 was more effective at reducing cell proliferation and migration than either agent alone. Finally, TU159 tongue cancer cell xenografts grown in athymic nude mice were treated thrice weekly for 4 weeks with vehicle, A12 (40 mg/kg i.p.), C225 (40 mg/kg i.p.), or both agents (n=8 mice per group; 2 tumors per mouse). Linear regression slope analysis showed significant differences in median tumor volume over time between all three treatment groups and the control group. Complete regression was seen in 31% (A12), 31% (C225), and 44% (A12 + C225) of tumors.
  
  
  CONCLUSIONS
  Here we found the overexpression of IGF-IR, the functional heterodimerization of IGF-IR and EGFR, and effective therapeutic targeting of these receptors in human head and neck cancer xenografts.
authors.affiliation: Department of Molecular and Cellular Oncology, The University of Texas M. D. Anderson Cancer Center, Houston, Texas 77030, USA.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Barnes
authors.forename: Kazufumi
authors.initials: K
authors.lastname: Ohshiro
authors.forename: Suresh K
authors.initials: SK
authors.lastname: Rayala
authors.forename: Adel K
authors.initials: AK
authors.lastname: El-Naggar
authors.forename: Rakesh
authors.initials: R
authors.lastname: Kumar
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000633:toxicity; D002453:Cell Cycle / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D045744:Cell Line, Tumor; D019281:Dimerization; D066246:ErbB Receptors / Q000235:genetics; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D006258:Head and Neck Neoplasms / Q000235:genetics* / Q000473:pathology; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D018613:Microscopy, Confocal; D017526:Receptor, IGF Type 1 / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism; D013002:Somatomedins / Q000494:pharmacology*; D014183:Transplantation, Heterologous
chemical_list: D000970:Antineoplastic Agents; D013002:Somatomedins; D066246:ErbB Receptors; D017526:Receptor, IGF Type 1