title: Relationship of EGFR mutations, expression, amplification, and polymorphisms to epidermal growth factor receptor inhibitors in the NCI60 cell lines.
abstract: OBJECTIVE
  The mechanism of sensitivity and resistance to epidermal growth factor receptor (EGFR) inhibitors is incompletely understood, particularly in cancers other than non-small-cell lung cancer (NSCLC). To understand the variable response to this class of drugs, we used the NCI60 cancer cell lines. We aimed to determine if there are interactions between EGFR expression, mutations, polymorphisms, and gene amplification, and whether these factors are associated with variability in response to EGFR inhibitors.
  
  
  METHODS
  The EGFRVIII and tyrosine kinase (TK) domain mutations were examined in the NCI60 cancer cell lines. Five polymorphisms, -216G/T, -191C/A, intron 1 (CA)n, R497K, and 2607A/G, were genotyped. EGFR amplification was also assessed with high-density single-nucleotide polymorphism chip and real-time PCR, respectively. The results were correlated with cytotoxicity data for erlotinib and other 11 EGFR inhibitors, as well as other publicly available data for these lines.
  
  
  RESULTS
  All 12 inhibitors behaved similarly. No EGFRVIII but putative TK mutations in two cell lines were found. Both mutant cell lines were insensitive to all inhibitors. Meanwhile, response did not correlate with EGFR amplification but with EGFR gene expression, especially in the cell lines with relatively normal gene status. In addition, EGFR expression was associated with the -216G/T polymorphism but not with the intron 1 (CA)n polymorphism. A combination of -216G/T and R497K polymorphisms was weakly associated with drug response.
  
  
  CONCLUSIONS
  These observations suggest that in addition to TK mutations, germ-line variability may also contribute to the pharmacodynamics of EGFR inhibitors, particularly when EGFR is genetically normal.
authors.affiliation: Department of Medicine, The University of Chicago, 5841 South Maryland Avenue, Chicago, IL 60637, USA.
authors.forename: Wanqing
authors.initials: W
authors.lastname: Liu
authors.forename: Xiaolin
authors.initials: X
authors.lastname: Wu
authors.forename: Wei
authors.initials: W
authors.lastname: Zhang
authors.forename: Raquel C
authors.initials: RC
authors.lastname: Montenegro
authors.forename: Donna Lee
authors.initials: DL
authors.lastname: Fackenthal
authors.forename: Jared A
authors.initials: JA
authors.lastname: Spitz
authors.forename: Lyn Mickley
authors.initials: LM
authors.lastname: Huff
authors.forename: Federico
authors.initials: F
authors.lastname: Innocenti
authors.forename: Soma
authors.initials: S
authors.lastname: Das
authors.forename: Edwin H
authors.initials: EH
authors.lastname: Cook
authors.forename: Nancy J
authors.initials: NJ
authors.lastname: Cox
authors.forename: Susan E
authors.initials: SE
authors.lastname: Bates
authors.forename: Mark J
authors.initials: MJ
authors.lastname: Ratain
mesh_terms: D045744:Cell Line, Tumor; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D066246:ErbB Receptors / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000235:genetics*; D005784:Gene Amplification; D006801:Humans; D015810:Linkage Disequilibrium; D009154:Mutation; D011110:Polymorphism, Genetic; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D017434:Protein Structure, Tertiary / Q000235:genetics; D011505:Protein-Tyrosine Kinases / Q000737:chemistry
chemical_list: D047428:Protein Kinase Inhibitors; C410723:epidermal growth factor receptor VIII; D066246:ErbB Receptors; D011505:Protein-Tyrosine Kinases