Konference: 2015 51th ASCO Annual Meeting - účast ČR
Kategorie: Genitourinární nádory
Číslo abstraktu: 4534
Autoři: MUDr. Ludmila Boublíková, Ph.D.; Mgr. Violeta Bakardjieva-Mihaylova; Mgr. Karolina Škvárová Kramarzová, Ph.D.; Mgr. Daniela Kužílková; Doc. MUDr. Tomáš Büchler, Ph.D.; MUDr. Pavel Dušek; MUDr. Marek Grega; MUDr. Blanka Rosová; Doc. MUDr. Zdeňka Vernerová, CSc.; MUDr. Petr Klézl; doc. MUDr. Roman Zachoval, Ph.D.; MUDr. Michal Pešl; MUDr. Marek Krolupper; Doc.MUDr. Martina Kubecová, Ph.D.; MUDr. Vladimíra Stáhalová; prof. MUDr. Marek Babjuk, CSc.; prof. MUDr. Jitka Abrahámová, DrSc.; prof. MUDr. Roman Kodet, CSc.; Prof.MUDr. Jan Trka, Ph.D.
Background: Wilms’ tumor gene 1 (WT1) is a transcription factor essential for normal development of the urogenital system and male gonadal formation. Its alterations have been found in Wilms’ tumor, other malignancies and testicular dysgenesis syndromes. We studied WT1 aberrations to address its role in the pathogenesis of testicular germ cell tumors (TGCT).Methods: In fresh-frozen samples of 85 TGCT (48 seminomas, 37 non-seminomas), 3 stromal tumors and 88 non-neoplastic controls, expression of total WT1 and its four main isoforms was quantified by qPCR. WT1 mutations were detected by direct and next-generation sequencing (NGS). The presence of WT1 protein was evaluated by standard immunohistochemistry.Results: The total WT1 expression was significantly lower (1 log) in TGCT than in the controls and stromal tumors (Kruskal-Wallis p < 0.0001), and was lower in seminomas than non-seminomas. Testicular tissue surrounding TGCT and containing in situ lesions expressed similar WT1 levels like other controls. WT1 isoforms lacking the exon 5 ([EX5-] isoforms A and C) were highly overexpressed in TGCT and stromal tumors in comparison with controls (Kruskal-Wallis, p < 0.0001). The isoform D, containing both main splice sites, was down-regulated in the tumors and this altered expression pattern was independent of total WT1 expression. Direct sequencing of exon 7 and 9 (with clustered hot-spots) could identify only 2 types of SNPs – synonymous rs16754 (31% of TGCT) and intronic rs5030274 (2%). By NGS however, 1 – 3 mutations in WT1 newly occurring in TGCT and not present in the paired controls were found in 59% of 22 analyzed cases. Staining for WT1 protein was positive in controls and undetectable in TGCT cells. Conclusions: The finding of total WT1 down-regulation in TGCT with the difference between seminomas and non-seminomas, the alteration of the isoform pattern with a pronounced shift to [EX5-] variants in TGCT independent of total WT1 levels, and the new occurrence of WT1 mutations in a high proportion of TGCT samples support the role of WT1 as a local tumor-suppressor gene in testicular tissues.
Supported by grants IGA NT/12414-5, GAUK56413, UNCE204012 and CDRO00064203FNM
Datum přednesení příspěvku: 1. 6. 2015