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A specific missense mutation in GTF2I occurs at high frequency in thymic epithelial tumors

ABSTRACT: Next generation sequencing of 28 thymic epithelial tumors (TETs) revealed a high frequency of GTF2I missense mutation (chr7:74146970T/A) in A thymomas, a relatively indolent subtype. The GTF2I mutation was confirmed in 82% of A and 74% of AB thymomas in a series of 274 TETs but was rare in aggressive subtypes, where recurrent mutations of known cancer genes were identified. Therefore, GTF2I mutation correlated with a better survival. GTF2I Beta and Delta isoforms were expressed in TETs and both mutant isoforms were able to stimulate cell proliferation in vitro. Thymic carcinomas presented a higher number of mutations than thymomas (average 43.5 and 18.4, respectively). Recurrent mutations of known cancer genes, including TP53, CYLD, CDKN2A, BAP1 and PBRM1 were identified in thymic carcinomas. These findings will complement the diagnostic work up of these rare tumors, and also help the development of a molecular classification, and assessment of prognosis and treatment strategies.

ORGANISM(S): Homo sapiens

PROVIDER: GSE57892 | GEO | 2014/06/24

SECONDARY ACCESSION(S): PRJNA248372

REPOSITORIES: GEO

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A specific missense mutation in GTF2I occurs at high frequency in thymic epithelial tumors

Project description:Next generation sequencing of 28 thymic epithelial tumors (TETs) revealed a high frequency of GTF2I missense mutation (chr7:74146970T/A) in A thymomas, a relatively indolent subtype. The GTF2I mutation was confirmed in 82% of A and 74% of AB thymomas in a series of 274 TETs but was rare in aggressive subtypes, where recurrent mutations of known cancer genes were identified. Therefore, GTF2I mutation correlated with a better survival. GTF2I Beta and Delta isoforms were expressed in TETs and both mutant isoforms were able to stimulate cell proliferation in vitro. Thymic carcinomas presented a higher number of mutations than thymomas (average 43.5 and 18.4, respectively). Recurrent mutations of known cancer genes, including TP53, CYLD, CDKN2A, BAP1 and PBRM1 were identified in thymic carcinomas. These findings will complement the diagnostic work up of these rare tumors, and also help the development of a molecular classification, and assessment of prognosis and treatment strategies. Tumor samples of 286 patients were collected from 4 different institutions: National Cancer Institute (Bethesda MD), Pisa University Hospital (Pisa, Italy), Padua University Hospital (Padua, Italy) and IRCCS Istituto Clinico Humanitas (Rozzano, Italy).

2014-06-24 | E-GEOD-57892 | biostudies-arrayexpress

A Knock-in Mouse Model of Thymoma with the GTF2I L424H Mutation

Project description:We previously identified a recurrent mutation L424H in the transcription factor GTF2I in thymic epithelial tumors. The precise role of the GTF2I mutation in these tumors is unclear. Here we describe the generation and characterization of a mouse model in which the Gtf2i L424H mutation was conditionally knocked-in in the Foxn1+ thymic epithelial cells. The Gtf2i mutation impairs development of thymic medulla and maturation of medullary thymic epithelial cells in the young mice and causes tumor formation in the thymus of the aged KI mice. To characterize the molecular features of murine thymomas, we performed digital spatial profiling with GeoMx moue whole transcriptome atlas assay with FFPE thymic tissues of 4 KI and 4 control mice.

2023-01-25 | GSE200784 | GEO

Mutant GTF2I induces cell transformation and metabolic alterations in thymic epithelial cells

Project description:The pathogenesis of thymic epithelial tumors (TETs) is poorly understood. Recently we reported the frequent occurrence of a missense mutation in the GTF2I gene in TETs and hypothesized that GTF2I mutation might contribute to thymic tumorigenesis. Expression of mutant TFII-I altered the transcriptome of normal thymic epithelial cells and upregulated several oncogenic genes. Gtf2i L424H knockin cells exhibited cell transformation, aneuploidy, and increase tumor growth and survival under glucose deprivation or DNA damage. Gtf2i mutation also increased the expression of several glycolytic enzymes, cyclooxygenase-2, and caused modifications of lipid metabolism. Elevated cyclooxygenase-2 expression by Gtf2i mutation was required for survival under metabolic stress and cellular transformation of thymic epithelial cells. Our findings identify GTF2I mutation as a new oncogenic driver that is responsible for transformation of thymic epithelial cells.

2022-03-02 | GSE127909 | GEO

GTF2I mutation induces metabolic alterations and cell transformation in thymic epithelial cells [II]

Project description:The molecular mechanisms underlying the pathogenesis of TETs are poorly understood. Recently we reported a common missense mutation on GTF2I gene in thymic tumors and hypothesized that GTF2I mutation might contribute to thymic tumorigenesis. Expression of mutant TFII-I altered the transcriptome of thymic epithelial cells and up-regulated several oncogenic genes. Using CRISPR/Cas9n, Gtf2i T1211A knock-in cells exhibited distinct features of cancerous cells including cell transformation, aneuploidy, tumor growth in xenograft, and survival after DNA damage or glucose deprivation. We also observed that Gtf2i mutation increased the expression of several glycolytic enzymes, cyclooxygenase-2, and altered lipid metabolism. Elevated COX-2 expression by Gtf2i mutation was required for survival under metabolic stress and cellular transformation of thymic epithelial cells. Our findings identify GTF2I mutation as a new oncogenic driver mutation that is responsible for transformation of thymic epithelial cells.

2022-03-02 | GSE127908 | GEO

GTF2I mutation induces metabolic alterations and cell transformation in thymic epithelial cells [I]

2022-03-02 | GSE127907 | GEO

Homo sapiens

Project description:GTF2I Mutations are Common in Thymic Epithelial Tumors

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A large microRNA cluster on chromosome 19 is a transcriptional hallmark of WHO type A and AB thymomas

Project description:Thymomas are one of the most rarely diagnosed malignancies. To better understand its biology and to identify therapeutic targets, we performed next-generation RNA sequencing. The RNA was sequenced from 13 thymic malignancies and 3 normal thymus glands. Validation of microRNA expression was performed on a separate set of 35 thymic malignancies. For cell-based studies, a thymoma cell line was used. Hierarchical clustering revealed 100% concordance between gene expression clusters and WHO subtype. A substantial differentiator was a large microRNA cluster on chr19q13.42 that was significantly overexpressed in all A and AB tumors and whose expression was virtually absent in the other thymomas and normal tissues. Overexpression of this microRNA cluster activates the PI3K/AKT/mTOR pathway. Treatment of a thymoma AB cell line with a panel of PI3K/AKT/mTOR inhibitors resulted in marked reduction of cell viability. A large microRNA cluster on chr19q13.42 is a transcriptional hallmark of type A and AB thymomas. Furthermore, this cluster activates the PI3K pathway, suggesting the possible exploration of PI3K inhibitors in patients with these subtypes of tumor. This work has led to the initiation of a phase II clinical trial of PI3K inhibition in relapsed or refractory thymomas. 13 thymic malignancies and 3 Normal Thymus RNA-Sequenced in triplicate

2016-04-06 | E-GEOD-79978 | biostudies-arrayexpress

Deciphering Tissue-based Proteome Signatures Revealed Novel Subtyping and Prognostic Markers for Thymic Epithelial Tumors

Project description:Thymic epithelial tumors (TETs) belong to a group of tumors that rarely occur, but have unresolved mechanisms and heterogeneous clinical behaviors. Current care of TET patients demands biomarkers of high sensitivity and specificity for accurate histological classification and prognosis management. In this study, 90 fresh-frozen tissue samples were recruited to generate a quantitative and systematic view of proteomic landscape of TETs by data independent acquisition mass spectrometry (DIA-MS) leading to discovery of novel classifying molecules among different TET subtypes.

2020-10-26 | PXD016498 | Pride

A large microRNA cluster on chromosome 19 is a transcriptional hallmark of WHO type A and AB thymomas

2016-04-06 | GSE79978 | GEO

GTF2I mutation induces metabolic alterations and cell transformation in thymic epithelial cells [II]

Project description:GTF2I mutation induces metabolic alterations and cell transformation in thymic epithelial cells [II]

| PRJNA525778 | ENA