title: MET gene amplification or EGFR mutation activate MET in lung cancers untreated with EGFR tyrosine kinase inhibitors.
abstract: We analyzed MET protein and copy number in NSCLC with or without EGFR mutations untreated with EGFR tyrosine kinase inhibitors (TKIs). MET copy number was examined in 28 NSCLC and 4 human bronchial epithelial cell lines (HBEC) and 100 primary tumors using quantitative real-time PCR. Positive results were confirmed by array comparative genomic hybridization and fluorescence in-situ hybridization. Total and phospho-MET protein expression was determined in 24 NSCLC and 2 HBEC cell lines using Western blot. EGFR mutations were examined for exon 19 deletions, T790M, and L858R. Knockdown of EGFR with siRNA was performed to examine the relation between EGFR and MET activation. High-level MET amplification was observed in 3 of 28 NSCLC cell lines and in 2 of 100 primary lung tumors that had not been treated with EGFR-TKIs. MET protein was highly expressed and phosphorylated in all the 3 cell lines with high MET amplification. In contrast, 6 NSCLC cell lines showed phospho-MET among 21 NSCLC cell lines without MET amplification (p = 0.042). Furthermore, those 6 cell lines harboring phospho-MET expression without MET amplification were all EGFR mutant (p = 0.0039). siRNA-mediated knockdown of EGFR abolished phospho-MET expression in examined 3 EGFR mutant cell lines of which MET gene copy number was not amplified. By contrast, phospho-MET expression in 2 cell lines with amplified MET gene was not down-regulated by knockdown of EGFR. Our results indicated that MET amplification was present in untreated NSCLC and EGFR mutation or MET amplification activated MET protein in NSCLC.
authors.affiliation: Department of Cancer and Thoracic Surgery, Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama University, Okayama, Japan.
authors.forename: Takafumi
authors.initials: T
authors.lastname: Kubo
authors.forename: Hiromasa
authors.initials: H
authors.lastname: Yamamoto
authors.forename: William W
authors.initials: WW
authors.lastname: Lockwood
authors.forename: Ilse
authors.initials: I
authors.lastname: Valencia
authors.forename: Junichi
authors.initials: J
authors.lastname: Soh
authors.forename: Michael
authors.initials: M
authors.lastname: Peyton
authors.forename: Masaru
authors.initials: M
authors.lastname: Jida
authors.forename: Hiroki
authors.initials: H
authors.lastname: Otani
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Fujii
authors.forename: Mamoru
authors.initials: M
authors.lastname: Ouchida
authors.forename: Nagio
authors.initials: N
authors.lastname: Takigawa
authors.forename: Katsuyuki
authors.initials: K
authors.lastname: Kiura
authors.forename: Kenji
authors.initials: K
authors.lastname: Shimizu
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Date
authors.forename: John D
authors.initials: JD
authors.lastname: Minna
authors.forename: Marileila
authors.initials: M
authors.lastname: Varella-Garcia
authors.forename: Wan L
authors.initials: WL
authors.lastname: Lam
authors.forename: Adi F
authors.initials: AF
authors.lastname: Gazdar
authors.forename: Shinichi
authors.initials: S
authors.lastname: Toyooka
mesh_terms: D000368:Aged; D001980:Bronchi / Q000166:cytology; D002289:Carcinoma, Non-Small-Cell Lung / Q000235:genetics / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D004847:Epithelial Cells / Q000166:cytology; D066246:ErbB Receptors / Q000037:antagonists & inhibitors / Q000235:genetics*; D005260:Female; D005784:Gene Amplification; D006801:Humans; D008175:Lung Neoplasms / Q000235:genetics* / Q000378:metabolism*; D008297:Male; D008875:Middle Aged; D009154:Mutation; D011518:Proto-Oncogene Proteins / Q000096:biosynthesis* / Q000235:genetics*; D019859:Proto-Oncogene Proteins c-met; D034741:RNA, Small Interfering / Q000378:metabolism; D017978:Receptors, Growth Factor / Q000096:biosynthesis* / Q000235:genetics*
chemical_list: D004791:Enzyme Inhibitors; D011518:Proto-Oncogene Proteins; D034741:RNA, Small Interfering; D017978:Receptors, Growth Factor; D066246:ErbB Receptors; C491743:MET protein, human; D019859:Proto-Oncogene Proteins c-met