title: KIT mutations are common in testicular seminomas.
abstract: Expression of KIT tyrosine kinase is critical for normal germ cell development and is observed in the majority of seminomas. Activating mutations in KIT are common in gastrointestinal stromal tumors and mastocytosis. In this study we examined the frequency and spectrum of KIT mutations in 54 testicular seminomas, 1 ovarian dysgerminoma and 37 non-seminomatous germ cell tumors (NSGCT). Fourteen seminomas (25.9%) contained exon 17 point mutations including D816V (6 cases), D816H (3 cases), Y823D (2 cases), and single examples of Y823C, N822K, and T801I. No KIT mutations were found in the ovarian dysgerminoma or the NSGCTs. In transient transfection assays, mutant isoforms D816V, D816H, Y823D, and N822K were constitutively phosphorylated in the absence of the natural ligand for KIT, stem cell factor (SCF). In contrast, activation of T801I and wild-type KIT required SCF. Mutants N822K and Y823D were inhibited by imatinib mesylate (Gleevec, previously STI571) whereas D816V and D816H were both resistant to imatinib mesylate. Biochemical evidence of KIT activation, as assessed by KIT phosphorylation and KIT association with phosphatidylinositol (PI) 3-kinase in tumor cell lysates, was largely confined to seminomas with a genomic KIT mutation. These findings suggest that activating KIT mutations may contribute to tumorigenesis in a subset of seminomas, but are not involved in NSGCT.
authors.affiliation: Division of Hematology and Oncology, Oregon Health and Science University Cancer Institute and Portland Veterans Affairs Medical Center, Portland, Oregon 97239, USA.
authors.forename: Kathleen
authors.initials: K
authors.lastname: Kemmer
authors.forename: Christopher L
authors.initials: CL
authors.lastname: Corless
authors.forename: Jonathan A
authors.initials: JA
authors.lastname: Fletcher
authors.forename: Laura
authors.initials: L
authors.lastname: McGreevey
authors.forename: Andrea
authors.initials: A
authors.lastname: Haley
authors.forename: Diana
authors.initials: D
authors.lastname: Griffith
authors.forename: Oscar W
authors.initials: OW
authors.lastname: Cummings
authors.forename: Cecily
authors.initials: C
authors.lastname: Wait
authors.forename: Ajia
authors.initials: A
authors.lastname: Town
authors.forename: Michael C
authors.initials: MC
authors.lastname: Heinrich
mesh_terms: D000818:Animals; D015153:Blotting, Western; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D004252:DNA Mutational Analysis; D004273:DNA, Neoplasm / Q000032:analysis*; D004407:Dysgerminoma / Q000235:genetics; D005260:Female; D018237:Germinoma / Q000235:genetics; D006801:Humans; D007150:Immunohistochemistry; D008297:Male; D009154:Mutation; D010051:Ovarian Neoplasms / Q000235:genetics; D011233:Precipitin Tests; D019009:Proto-Oncogene Proteins c-kit / Q000235:genetics*; D018239:Seminoma / Q000235:genetics*; D013736:Testicular Neoplasms / Q000235:genetics*; D014162:Transfection
chemical_list: D004273:DNA, Neoplasm; D019009:Proto-Oncogene Proteins c-kit