title: EGFR is not a major driver for osteosarcoma cell growth in vitro but contributes to starvation and chemotherapy resistance.
abstract: BACKGROUND
  Enhanced signalling via the epidermal growth factor receptor (EGFR) is a hallmark of multiple human carcinomas. However, in recent years data have accumulated that EGFR might also be hyperactivated in human sarcomas. Aim of this study was to investigate the influence of EGFR inhibition on cell viability and its interaction with chemotherapy response in osteosarcoma cell lines.
  
  
  METHODS
  We have investigated a panel of human osteosarcoma cell lines regarding EGFR expression and downstream signalling. To test its potential applicability as therapeutic target, inhibition of EGFR by gefitinib was combined with osteosarcoma chemotherapeutics and cell viability, migration, and cell death assays were performed.
  
  
  RESULTS
  Osteosarcoma cells expressed distinctly differing levels of functional EGFR reaching in some cases high amounts. Functionality of EGFR in osteosarcoma cells was proven by EGF-mediated activation of both MAPK and PI3K/AKT pathway (determined by phosphorylation of ERK1/2, AKT, S6, and GSK3β). The EGFR-specific inhibitor gefitinib blocked EGF-mediated downstream signal activation. At standard in vitro culture conditions, clinically achievable gefitinib doses demonstrated only limited cytotoxic activity, however, significantly reduced long-term colony formation and cell migration. In contrast, under serum-starvation conditions active gefitinib doses were distinctly reduced while EGF promoted starvation survival. Importantly, gefitinib significantly supported the anti-osteosarcoma activities of doxorubicin and methotrexate regarding cell survival and migratory potential.
  
  
  CONCLUSIONS
  Our data suggest that EGFR is not a major driver for osteosarcoma cell growth but contributes to starvation- and chemotherapy-induced stress survival. Consequently, combination approaches including EGFR inhibitors should be evaluated for treatment of high-grade osteosarcoma patients.
authors.affiliation: Department of Orthopaedics, Medical University of Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria. florian.sevelda@meduniwien.ac.at.|Institute of Cancer Research and Comprehensive Cancer Center, Department of Medicine I, Medical University Vienna, Borschkegasse 8a, 1090, Vienna, Austria. florian.sevelda@meduniwien.ac.at.
authors.forename: Florian
authors.initials: F
authors.lastname: Sevelda
authors.affiliation: Institute of Cancer Research and Comprehensive Cancer Center, Department of Medicine I, Medical University Vienna, Borschkegasse 8a, 1090, Vienna, Austria. lisa.mayr@meduniwien.ac.at.
authors.forename: Lisa
authors.initials: L
authors.lastname: Mayr
authors.affiliation: Department of Orthopaedics, Medical University of Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria. bernd.kubista@meduniwien.ac.at.
authors.forename: Bernd
authors.initials: B
authors.lastname: Kubista
authors.affiliation: Institute of Cancer Research and Comprehensive Cancer Center, Department of Medicine I, Medical University Vienna, Borschkegasse 8a, 1090, Vienna, Austria. daniela.loetsch@meduniwien.ac.at.
authors.forename: Daniela
authors.initials: D
authors.lastname: Lötsch
authors.affiliation: Institute of Cancer Research and Comprehensive Cancer Center, Department of Medicine I, Medical University Vienna, Borschkegasse 8a, 1090, Vienna, Austria. sushilla.vanschoonhoven@meduniwien.ac.at.
authors.forename: Sushilla
authors.initials: S
authors.lastname: van Schoonhoven
authors.affiliation: Department of Orthopaedics, Medical University of Vienna, Waehringer Guertel 18-20, 1090, Vienna, Austria. reinhard.windhager@meduniwien.ac.at.
authors.forename: Reinhard
authors.initials: R
authors.lastname: Windhager
authors.affiliation: Institute of Cancer Research and Comprehensive Cancer Center, Department of Medicine I, Medical University Vienna, Borschkegasse 8a, 1090, Vienna, Austria. christine.pirker@meduniwien.ac.at.
authors.forename: Christine
authors.initials: C
authors.lastname: Pirker
authors.affiliation: Institute of Cancer Research and Comprehensive Cancer Center, Department of Medicine I, Medical University Vienna, Borschkegasse 8a, 1090, Vienna, Austria. michael.micksche@meduniwien.ac.at.
authors.forename: Michael
authors.initials: M
authors.lastname: Micksche
authors.affiliation: Institute of Cancer Research and Comprehensive Cancer Center, Department of Medicine I, Medical University Vienna, Borschkegasse 8a, 1090, Vienna, Austria. walter.berger@meduniwien.ac.at.
authors.forename: Walter
authors.initials: W
authors.lastname: Berger
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis; D001859:Bone Neoplasms / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism*; D002453:Cell Cycle; D045744:Cell Line, Tumor; D002465:Cell Movement; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D019008:Drug Resistance, Neoplasm / Q000235:genetics; D066246:ErbB Receptors / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D000077156:Gefitinib; D015870:Gene Expression; D006801:Humans; D012516:Osteosarcoma / Q000188:drug therapy / Q000235:genetics / Q000378:metabolism*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D011799:Quinazolines / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D000970:Antineoplastic Agents; D047428:Protein Kinase Inhibitors; D011799:Quinazolines; D019869:Phosphatidylinositol 3-Kinases; D066246:ErbB Receptors; D051057:Proto-Oncogene Proteins c-akt; D000077156:Gefitinib