title: Kinetics of EGFR expression during fractionated irradiation varies between different human squamous cell carcinoma lines in nude mice.
abstract: OBJECTIVE
  Preclinical and clinical data indicate that high pretherapeutic EGFR expression is associated with poor local tumour control, possibly caused by a high repopulation rate of clonogenic cells during radiotherapy in these tumours. Previous data reported from our laboratory showed a correlation between EGFR expression and acceleration of repopulation in poorly differentiated FaDu human squamous cell carcinoma (SCC) during fractionated irradiation. To test whether this is a general phenomenon, two further SCC were investigated in the present study.
  
  
  METHODS
  GL and UT-SCC-14, two moderately well differentiated and keratinising hSCC, were grown as xenografts in nude mice. Functional data on the repopulation kinetics during fractionated irradiation for these tumour models have been previously determined. The expression of EGFR during fractionation was analysed by immunohistochemistry. Endpoints were the membrane-staining score and the proportion of EGFR-positive cells (EGFR labelling index).
  
  
  RESULTS
  Different kinetics of EGFR expression during fractionated RT were found. In UT-SCC-14, EGFR staining score and labelling index increased significantly during radiotherapy. In GL SCC, the EGFR expression was unchanged. Both tumours are characterized by a small but significant repopulation rate during radiotherapy.
  
  
  CONCLUSIONS
  The expression of EGFR may change significantly during fractionated irradiation. No clear correlation between EGFR expression and the repopulation kinetics of clonogenic tumour cells during fractionated irradiation was found. The changes in EGFR expression during irradiation warrant further investigation on their prognostic implications and on their importance for therapeutic interventions.
authors: Clinic of Radiation Oncology, Medical Faculty Carl Gustav Carus, University of Technology, Dresden, Germany. wolfgang.eicheler@mailbox.tu-dresden.de
authors: Wolfgang
authors: W
authors: Eicheler
authors: Mechthild
authors: M
authors: Krause
authors: Franziska
authors: F
authors: Hessel
authors: Daniel
authors: D
authors: Zips
authors: Michael
authors: M
authors: Baumann
mesh_terms: D000818:Animals; D002294:Carcinoma, Squamous Cell / Q000378:metabolism / Q000473:pathology / Q000532:radiotherapy*; D045744:Cell Line, Tumor; D019583:Dose Fractionation, Radiation; D066246:ErbB Receptors / Q000378:metabolism*; D006801:Humans; D007150:Immunohistochemistry; D051379:Mice; D008819:Mice, Nude; D009368:Neoplasm Transplantation; D014407:Tumor Cells, Cultured
chemical_list: D066246:ErbB Receptors