title: Dual targeting of EGFR and focal adhesion kinase in 3D grown HNSCC cell cultures.
abstract: OBJECTIVE
  Epidermal growth factor receptor (EGFR) and focal adhesion kinase (FAK) show frequent overexpression and hyperactivity in various human malignancies including head and neck squamous cell carcinomas (HNSCC). To examine effects of dual EGFR/FAK inhibition on cellular radiosensitivity of HNSCC cells in a more physiological environment, we employed a previously established laminin-rich extracellular matrix (lrECM) based three-dimensional (3D) cell culture model.
  
  
  METHODS
  UTSCC15 and SAS HNSCC cell lines stably transfected with EGFR-CFP or CFP were used. Single or combined EGFR (Cetuximab, siRNA) and FAK (TAE226, siRNA) inhibition were accomplished prior to measuring clonogenic survival and protein expression and phosphorylation. Immunofluorescence enabled visualization of EGFR-CFP and FAK.
  
  
  RESULTS
  Cetuximab resulted in higher radiosensitization in EGFR-CFP overexpressing cell lines than CFP controls. Single EGFR or FAK inhibition mediated radiosensitization, while dual EGFR/FAK targeting further augmented this effect. Despite signaling alterations upon Cetuximab and siRNA knockdown, analysis of protein expression and phosphorylation indicates EGFR and FAK signaling coexistence without obvious overlap.
  
  
  CONCLUSIONS
  Combined EGFR/FAK targeting yielded stronger radiosensitization than either approach alone, which might be based on non-overlapping downstream signaling. Whether dual targeting of EGFR and FAK can reasonably be combined with radiotherapy and chemotherapy needs clarification.
authors.affiliation: OncoRay-National Center for Radiation Research in Oncology, Dresden University of Technology, Germany.
authors.forename: Iris
authors.initials: I
authors.lastname: Eke
authors.forename: Nils
authors.initials: N
authors.lastname: Cordes
mesh_terms: D000911:Antibodies, Monoclonal / Q000494:pharmacology*; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D015153:Blotting, Western; D002294:Carcinoma, Squamous Cell / Q000532:radiotherapy; D018929:Cell Culture Techniques / Q000379:methods*; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D000068818:Cetuximab; D004305:Dose-Response Relationship, Drug; D066246:ErbB Receptors / Q000037:antagonists & inhibitors*; D051416:Focal Adhesion Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors*; D006258:Head and Neck Neoplasms / Q000532:radiotherapy; D006801:Humans; D009025:Morpholines / Q000494:pharmacology*; D010766:Phosphorylation; D011838:Radiation-Sensitizing Agents / Q000494:pharmacology*; D015398:Signal Transduction; D000077195:Squamous Cell Carcinoma of Head and Neck; D014162:Transfection; D014407:Tumor Cells, Cultured / Q000187:drug effects
chemical_list: D000911:Antibodies, Monoclonal; D061067:Antibodies, Monoclonal, Humanized; D000970:Antineoplastic Agents; D009025:Morpholines; D011838:Radiation-Sensitizing Agents; C524632:TAE226; D066246:ErbB Receptors; D051416:Focal Adhesion Protein-Tyrosine Kinases; D000068818:Cetuximab