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Somatic mutation profiles of clear cell endometrial tumors revealed by whole exome and targeted gene sequencing.

ABSTRACT: BACKGROUND:The molecular pathogenesis of clear cell endometrial cancer (CCEC), a tumor type with a relatively unfavorable prognosis, is not well defined. We searched exome-wide for novel somatically mutated genes in CCEC and assessed the mutational spectrum of known and candidate driver genes in a large cohort of cases. METHODS:We conducted whole exome sequencing of paired tumor-normal DNAs from 16 cases of CCEC (12 CCECs and the CCEC components of 4 mixed histology tumors). Twenty-two genes-of-interest were Sanger-sequenced from another 47 cases of CCEC. Microsatellite instability (MSI) and microsatellite stability (MSS) were determined by genotyping 5 mononucleotide repeats. RESULTS:Two tumor exomes had relatively high mutational loads and MSI. The other 14 tumor exomes were MSS and had 236 validated nonsynonymous or splice junction somatic mutations among 222 protein-encoding genes. Among the 63 cases of CCEC in this study, we identified frequent somatic mutations in TP53 (39.7%), PIK3CA (23.8%), PIK3R1 (15.9%), ARID1A (15.9%), PPP2R1A (15.9%), SPOP (14.3%), and TAF1 (9.5%), as well as MSI (11.3%). Five of 8 mutations in TAF1, a gene with no known role in CCEC, localized to the putative histone acetyltransferase domain and included 2 recurrently mutated residues. Based on patterns of MSI and mutations in 7 genes, CCEC subsets molecularly resembled serous endometrial cancer (SEC) or endometrioid endometrial cancer (EEC). CONCLUSION:Our findings demonstrate molecular similarities between CCEC and SEC and EEC and implicate TAF1 as a novel candidate CCEC driver gene. Cancer 2017;123:3261-8. © 2017 American Cancer Society.

SUBMITTER: Le Gallo M

PROVIDER: S-EPMC5587124 | biostudies-literature | 2017 Sep

REPOSITORIES: biostudies-literature

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Somatic mutation profiles of clear cell endometrial tumors revealed by whole exome and targeted gene sequencing.

Le Gallo Matthieu M Rudd Meghan L ML Urick Mary Ellen ME Hansen Nancy F NF Zhang Suiyuan S Lozy Fred F Sgroi Dennis C DC Vidal Bel August A Matias-Guiu Xavier X Broaddus Russell R RR Lu Karen H KH Levine Douglas A DA Mutch David G DG Goodfellow Paul J PJ Salvesen Helga B HB Mullikin James C JC Bell Daphne W DW

Cancer 20170509 17

<h4>Background</h4>The molecular pathogenesis of clear cell endometrial cancer (CCEC), a tumor type with a relatively unfavorable prognosis, is not well defined. We searched exome-wide for novel somatically mutated genes in CCEC and assessed the mutational spectrum of known and candidate driver genes in a large cohort of cases.<h4>Methods</h4>We conducted whole exome sequencing of paired tumor-normal DNAs from 16 cases of CCEC (12 CCECs and the CCEC components of 4 mixed histology tumors). Twent ...[more]

PMID: 28485815

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Project description:Clear cell renal cell carcinoma (ccRCC) is among the most aggressive histologic subtypes of kidney cancer, representing about 3% of all human cancers. Patients at stage IV have nearly 60% of mortality in 2-3 years after diagnosis. To date, most ccRCC studies have used DNA microarrays and targeted sequencing of a small set of well-established, commonly altered genes. An exception is the large multi-omics study of The Cancer Genome Atlas Kidney Renal Clear Cell Carcinoma (TCGA-KIRC), which identified new ccRCC genes based on whole exome-sequencing (WES) data, and molecular prognostic signatures based on transcriptomics, epigenetics and proteomics data. Applying WES to simultaneously interrogate virtually all exons in the human genome for somatic variation, here we analyzed the burden of coding somatic mutations in metastatic ccRCC primary tumors, and its association with patient mortality from cancer, in patients who received VEGF receptor-targeting drugs as the first-line therapy. To this end, we sequenced the exomes of ten tumor-normal pairs of ccRCC patient tissues from primary biopsies at >100× mean depth and called somatic coding variation. Mutation burden analysis prioritized 138 genes linked to patient mortality. A gene set enrichment analysis evidenced strong statistical support for the abundance of genes involved in the development of kidney cancer (p = 2.31 × 10-9) and carcinoma (p = 1.22 × 10-5), with 49 genes having direct links with kidney cancer according to the published records. Two of these genes, SIPA1L2 and EIF3A, demonstrated independent associations with mortality in TCGA-KIRC project data. Besides, three mutational signatures were found to be operative in the tumor exomes, one of which (COSMIC signature 12) has not been previously reported in ccRCC. Selection analysis yielded no detectable evidence of overall positive or negative selection, with the exome-wide number of nonsynonymous substitutions per synonymous site reflecting largely neutral tumor evolution. Despite the limited sample size, our results provide evidence for candidate genes where somatic mutation burden is tentatively associated with patient mortality in metastatic ccRCC, offering new potential pharmacological targets and a basis for further validation studies.

Project description:BackgroundWhile the somatic mutation profiles of renal cell carcinoma (RCC) have been revealed by several studies worldwide, the overwhelming majority of those were not derived from Chinese patients. The landscape of somatic alterations in RCC from Chinese patients still needs to be elucidated to determine whether discrepancies exist between Chinese patients and sufferers from other countries and regions.MethodsWe collected specimens from 26 Chinese patients with primary RCC, including 15 clear cell renal cell carcinoma (ccRCC) samples, 5 papillary renal cell carcinoma (PRCC) samples and 6 chromophobe renal cell carcinoma (ChRCC) samples. Genomic DNAs were isolated from paired tumor-normal tissues and subjected to whole exome sequencing (WES). Immunohistochemistry analysis was performed to detect the programmed death ligand 1 (PD-L1) expression in tumor tissues.ResultsA total of 1920 nonsynonymous somatic variants in exons and 86 mutations at splice junctions were revealed. The tumor mutation burden of ccRCC was significantly higher than that of ChRCC (P < 0.05). For both ccRCC and PRCC, the most frequent substitution in somatic missense mutations was T:A > A:T, which was different from that recorded in the COSMIC database. Among eight significantly mutated genes in ccRCC in the TCGA database, six genes were verified in our study including VHL (67%), BAP1 (13%), SETD2 (13%), PBRM1 (7%), PTEN (7%) and MTOR (7%). All the mutations detected in those genes had not been reported in ccRCC before, except for alterations in VHL and PBRM1. Regarding the frequently mutated genes in PRCC in our study, DEPDC4 (p.E293A, p.T279A), PNLIP (p.N401Y, p.F342L) and SARDH (p.H554Q, p.M1T) were newly detected gene mutations predicted to be deleterious. As the most recurrently mutated gene in ChRCC in the TCGA dataset, TP53 (p.R81Q) was somatically altered only in one ChRCC case in this study. The HIF-1 signaling pathway was the most affected pathway in ccRCC, while the PI3K-Akt signaling pathway was altered in all of the three RCC types. Membranous PD-L1 expression was positive in tumor cells from 6/26 (23%) RCC specimens. The PD-L1-positive rate was higher in RCC samples with the somatically mutated genes CSPG4, DNAH11, INADL and TMPRSS13 than in specimens without those (P < 0.05).ConclusionsUsing WES, we identified somatic mutations in 26 Chinese patients with RCC, which enriched the racial diversity of the somatic mutation profiles of RCC subjects, and revealed a few discrepancies in molecular characterizations between our study and published datasets. We also identified numerous newly detected somatic mutations, which further supplements the somatic mutation landscape of RCC. Moreover, 4 somatically mutated genes, including CSPG4, DNAH11, INADL and TMPRSS13, might be promising predictive factors of PD-L1-positive expression in RCC tumor cells.

Dataset Information

Somatic mutation profiles of clear cell endometrial tumors revealed by whole exome and targeted gene sequencing.

Publications

Somatic mutation profiles of clear cell endometrial tumors revealed by whole exome and targeted gene sequencing.

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