title: Expression of selected gene for acquired drug resistance to EGFR-TKI in lung adenocarcinoma.
abstract: BACKGROUND
  Individualized treatment is an attractive challenge that may allow for more effective and safer treatment of human disease. Activating mutations in the epidermal growth factor receptor (EGFR) gene in lung adenocarcinoma are associated with a dramatic clinical response to EGFR-tyrosine kinase inhibitors (TKIs). However, patients often experience a relapse after treatment with EGFR-TKIs, even when the tumors are initially highly sensitive. However, the "whole picture" regarding acquired resistance remains unclear.
  
  
  METHODS
  Tumor specimens were collected from 11 lung adenocarcinoma patients before and after treatment with gefitinib. The status of the EGFR and K-ras genes were investigated by PCR-based analyses. Immunohistochemistry and real-time PCR assays were used to evaluate the MET gene in terms of its tyrosine phosphorylation and amplification, respectively. The expression of HGF, PTEN, and EGR-1, and changes in the epithelial-mesenchymal transition (EMT) status including the expression of E-cadherin and gamma-catenin as epithelial markers, and vimentin and fibronectin as mesenchymal markers, were evaluated by immunohistochemistry.
  
  
  RESULTS
  Seven (64%) of the gefitinib refractory tumors exhibited a secondary threonine-to-methionine mutation at codon 790 in EGFR (T790M). All of the tumors had wild type K-ras gene expression. No MET amplification was detected in any of the samples, nor was there phosphorylation of MET detected in any of the resistant samples. Neither MET gene amplification, nor the overexpression of HGF was observed in samples without the T790M mutation. A strong expression of HGF was detected in 6 of 8 specimens with the T790M mutation. Three (38%) of 8 cases showed a loss of PTEN in samples with the T790M mutation. A loss of EGR-1 was detected in 2 (29%) of 7 cases, including one tumor without PTEN. Four (57%) of 7 cases showed positive expression of phosphorylated Akt (p-Akt). A change in the EMT status between pre-and post-treatment was observed in 4 (44%) of 9 cases. In all examined samples cases, some alterations of gene or proteins were observed.
  
  
  CONCLUSIONS
  The current results showed that these alterations in gene or protein expression can account for all resistant mechanisms. This phenomenon suggests the existence of complicated relationships among acquired resistance-related genes.
authors.affiliation: Second Department of Surgery, School of Medicine, University of Occupational and Environmental Health, Yahatanishiku, Kitakyushu, Japan. hidetaka@med.uoeh-u.ac.jp
authors.forename: Hidetaka
authors.initials: H
authors.lastname: Uramoto
authors.forename: Hidehiko
authors.initials: H
authors.lastname: Shimokawa
authors.forename: Takeshi
authors.initials: T
authors.lastname: Hanagiri
authors.forename: Michihiko
authors.initials: M
authors.lastname: Kuwano
authors.forename: Mayumi
authors.initials: M
authors.lastname: Ono
mesh_terms: D000230:Adenocarcinoma / Q000235:genetics / Q000473:pathology / Q000628:therapy*; D000368:Aged; D000369:Aged, 80 and over; D000970:Antineoplastic Agents / Q000008:administration & dosage* / Q000494:pharmacology; D015415:Biomarkers / Q000378:metabolism; D015820:Cadherins / Q000235:genetics / Q000378:metabolism; D019008:Drug Resistance, Neoplasm / Q000235:genetics; D051766:Early Growth Response Protein 1 / Q000235:genetics / Q000378:metabolism; D058750:Epithelial-Mesenchymal Transition / Q000187:drug effects / Q000235:genetics; D066246:ErbB Receptors / Q000037:antagonists & inhibitors; D005260:Female; D005353:Fibronectins / Q000235:genetics / Q000378:metabolism; D000077156:Gefitinib; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D008175:Lung Neoplasms / Q000235:genetics / Q000473:pathology / Q000628:therapy*; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local; D051059:PTEN Phosphohydrolase / Q000235:genetics / Q000378:metabolism; D011518:Proto-Oncogene Proteins / Q000235:genetics / Q000378:metabolism*; D019859:Proto-Oncogene Proteins c-met / Q000235:genetics / Q000378:metabolism; D016283:Proto-Oncogene Proteins p21(ras); D011799:Quinazolines / Q000008:administration & dosage* / Q000494:pharmacology; D051185:gamma Catenin / Q000235:genetics / Q000378:metabolism; D018631:ras Proteins / Q000235:genetics / Q000378:metabolism*
chemical_list: D000970:Antineoplastic Agents; D015415:Biomarkers; D015820:Cadherins; C497325:EGR1 protein, human; D051766:Early Growth Response Protein 1; D005353:Fibronectins; C117307:KRAS protein, human; D011518:Proto-Oncogene Proteins; D011799:Quinazolines; D051185:gamma Catenin; D066246:ErbB Receptors; D019859:Proto-Oncogene Proteins c-met; D051059:PTEN Phosphohydrolase; D016283:Proto-Oncogene Proteins p21(ras); D018631:ras Proteins; D000077156:Gefitinib