title: Mutational status of EGFR and KIT in thymoma and thymic carcinoma.
abstract: This study was conducted to evaluate the prevalence of EGFR and KIT mutations in thymomas and thymic carcinomas as a means of exploring the potential for molecularly targeted therapy with tyrosine kinase inhibitors. Genomic DNA was isolated from 41 paraffin-embedded tumor samples obtained from 24 thymomas and 17 thymic carcinomas. EGFR exons 18, 19, and 21, and KIT exons 9, 11, 13, and 17, were analyzed for mutations by PCR and direct sequencing. Protein expression of EGFR and KIT was evaluated immunohistochemically. EGFR mutations were detected in 2 of 20 thymomas, but not in any of the thymic carcinomas. All of the EGFR mutations detected were missense mutations (L858R and G863D) in exon 21. EGFR protein was expressed in 71% of the thymomas and 53% of the thymic carcinomas. The mutational analysis of KIT revealed only a missense mutation (L576P) in exon 11 of one thymic carcinoma. KIT protein was expressed in 88% of the thymic carcinomas and 0% of the thymomas. The results of this study indicate that EGFR and KIT mutations in thymomas and thymic carcinomas are rare, but that many of the tumors express EGFR or KIT protein.
authors.affiliation: Division of Thoracic Oncology, National Cancer Center Hospital East, 6-5-1 Kashiwanoha, Kashiwa, Chiba 277-8577, Japan. kyoh@east.ncc.go.jp
authors.forename: Kiyotaka
authors.initials: K
authors.lastname: Yoh
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Nishiwaki
authors.forename: Genichiro
authors.initials: G
authors.lastname: Ishii
authors.forename: Koichi
authors.initials: K
authors.lastname: Goto
authors.forename: Kaoru
authors.initials: K
authors.lastname: Kubota
authors.forename: Hironobu
authors.initials: H
authors.lastname: Ohmatsu
authors.forename: Seiji
authors.initials: S
authors.lastname: Niho
authors.forename: Kanji
authors.initials: K
authors.lastname: Nagai
authors.forename: Nagahiro
authors.initials: N
authors.lastname: Saijo
mesh_terms: D000328:Adult; D000368:Aged; D004252:DNA Mutational Analysis; D066246:ErbB Receptors / Q000235:genetics* / Q000378:metabolism; D005091:Exons / Q000235:genetics; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007124:Immunoenzyme Techniques; D008297:Male; D008875:Middle Aged; D020125:Mutation, Missense / Q000235:genetics*; D009367:Neoplasm Staging; D016133:Polymerase Chain Reaction; D011379:Prognosis; D019009:Proto-Oncogene Proteins c-kit / Q000235:genetics* / Q000378:metabolism; D013945:Thymoma / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D013953:Thymus Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology
chemical_list: C512478:EGFR protein, human; D066246:ErbB Receptors; D019009:Proto-Oncogene Proteins c-kit