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Endometrial cancer is the 6th most commonly diagnosed cancer among women worldwide, causing ~74,000 deaths annually 1. Serous endometrial cancers are a clinically aggressive subtype with a poorly defined genetic etiology 2-4. We used whole exome sequencing (WES) to comprehensively search for somatic mutations within ~22,000 protein-encoding genes among 13 primary serous endometrial tumors. We subsequently resequenced 18 genes that were mutated in more than one tumor, and/or were genes that formed an enriched functional grouping, from 40 additional serous tumors. We identified high frequencies of somatic mutations in CHD4 (17%), EP300 (8%), ARID1A (6%), TSPYL2 (6%), FBXW7 (29%), SPOP (8%), MAP3K4 (6%) and ABCC9 (6%). Overall, 36.5% of serous tumors had mutated a chromatin-remodeling gene and 35% had mutated a ubiquitin ligase complex gene, implicating the frequent mutational disruption of these processes in the molecular pathogenesis of one of the deadliest forms of endometrial cancer.

Purpose: The goal of this study was to comprehensively define the incidence of mutations in all exons of PIK3CA in both endometrioid endometrial cancer (EEC) and nonendometrioid endometrial cancer (NEEC). Experimental Design: We resequenced all coding exons of PIK3CA and PTEN, and exons 1 and 2 of KRAS, from 108 primary endometrial tumors. Somatic mutations were confirmed by sequencing matched normal DNAs. The biochemical properties of a subset of novel PIK3CA mutations were determined by exogenously expressing wild type and mutant constructs in U2OS cells and measuring levels of AKTSer473 phosphorylation. Results: Somatic PIK3CA mutations were detected in 52.4% of 42 EECs and 33.3% of 66 NEECs. Half (29 of 58) of all nonsynonymous PIK3CA mutations were in exons 1–7 and half were in exons 9 and 20. The exons 1–7 mutations localized to the ABD, ABD-RBD linker and C2 domains of p110α. Within these regions, Arg88, Arg93, Gly106, Lys111, Glu365, and Glu453, were recurrently mutated; Arg88, Arg93, and Lys111 formed mutation hotspots. The p110α-R93W, -G106R, -G106V, -K111E, -delP449-L455, and -E453K mutants led to increased levels of phospho-AKTSer473 compared to wild-type p110α. Overall, 62% of exons 1–7 PIK3CA mutants and 64% of exons 9–20 PIK3CA mutants were activating; 72% of exon 1–7 mutations have not previously been reported in endometrial cancer. Conclusions: Our study identified a new subgroup of endometrial cancer patients with activating mutations in the amino-terminal domains of p110α; these patients might be appropriate for consideration in clinical trials of targeted therapies directed against the PI3K pathway. Clin Cancer Res; 17(6); 1331–40. ©2011 AACR.

Background Endometrial cancer (EC) is the 8th leading cause of cancer death amongst American women. Most ECs are endometrioid, serous, or clear cell carcinomas, or an admixture of histologies. Serous and clear ECs are clinically aggressive tumors for which alternative therapeutic approaches are needed. The purpose of this study was to search for somatic mutations in the tyrosine kinome of serous and clear cell ECs, because mutated kinases can point to potential therapeutic targets. Methods In a mutation discovery screen, we PCR amplified and Sanger sequenced the exons encoding the catalytic domains of 86 tyrosine kinases from 24 serous, 11 clear cell, and 5 mixed histology ECs. For somatically mutated genes, we next sequenced the remaining coding exons from the 40 discovery screen tumors and sequenced all coding exons from another 72 ECs (10 clear cell, 21 serous, 41 endometrioid). We assessed the copy number of mutated kinases in this cohort of 112 tumors using quantitative real time PCR, and we used immunoblotting to measure expression of these kinases in endometrial cancer cell lines. Results Overall, we identified somatic mutations in TNK2 (tyrosine kinase non-receptor, 2) and DDR1 (discoidin domain receptor tyrosine kinase 1) in 5.3% (6 of 112) and 2.7% (3 of 112) of ECs. Copy number gains of TNK2 and DDR1 were identified in another 4.5% and 0.9% of 112 cases respectively. Immunoblotting confirmed TNK2 and DDR1 expression in endometrial cancer cell lines. Three of five missense mutations in TNK2 and one of two missense mutations in DDR1 are predicted to impact protein function by two or more in silico algorithms. The TNK2P761Rfs*72 frameshift mutation was recurrent in EC, and the DDR1R570Q missense mutation was recurrent across tumor types. Conclusions This is the first study to systematically search for mutations in the tyrosine kinome in clear cell endometrial tumors. Our findings indicate that high-frequency somatic mutations in the catalytic domains of the tyrosine kinome are rare in clear cell ECs. We uncovered ten new mutations in TNK2 and DDR1 within serous and endometrioid ECs, thus providing novel insights into the mutation spectrum of each gene in EC. Electronic supplementary material The online version of this article (doi:10.1186/1471-2407-14-884) contains supplementary material, which is available to authorized users.

Endometrial cancers (ECs) arise from the inner epithelial lining of the uterus. At diagnosis, the majority of ECs are carcinomas of endometrioid, serous, or clear cell histologies, or an admixture of at least two of these histological subtypes. Serous and clear ECs are rare at presentation but contribute disproportionately to mortality from EC. Thus, there is an acute need for novel therapeutic approaches to treat serous and clear cell ECs. Small molecule inhibitors directed against tyrosine kinases have shown clinical efficacy in other types of cancer in which the target kinase is mutationally activated. Here, we used Sanger sequencing to systematically search for somatic mutations within 527 exons that encode the catalytic domains of 85 tyrosine kinases from 23 serous, 10 clear cell, and 5 mixed histology ECs. For mutated genes, we extended the screen to another 73 ECs (21 serous, 10 clear cell, 42 endometrioid). Genes that were mutated in both the primary and secondary screens were resequenced in a tertiary screen to search for mutations in all coding exons among the entire panel of 111 endometrial tumors. Overall, we uncovered nonsynonymous somatic mutations of ACK1, DDR1, and KDR in 5.4%, 3.6%, and 1% of ECs. Serous tumors had mutated ACK1, DDR1 and KDR in 2.3%, 4.5%, and 2.3% of cases. Clear cell tumors had mutated ACK1 in 5% of cases. Endometrioid tumors had mutated DDR1 in 2.3% of cases. Immunoblotting confirmed that ACK1 and DDR1 are endogenously expressed in endometrial cancer cell-lines. Eighty-seven percent (7 of 8) of ACK1 mutations and 50% (2 of 4) of DDR1 mutations are predicted to impact protein function. To our knowledge this is the first report of ACK1 and DDR1 mutations in endometrial cancer. Our findings warrant future studies to determine whether the ACK1 and DDR1 mutations uncovered here are pathogenic. Citation Format: Meghan L. Rudd, Hassan Mohamed, Jessica C. Price, Mary Ellen Urick, Andrea J. O'Hara, Matthieu Le Gallo, NISC Comparative Sequencing Program, Pedro Cruz, Suiyuan Zhang, James Mullikin, Maria J. Merino, Daphne W. Bell. Mutational analysis of the tyrosine kinome in serous and clear cell endometrial cancers. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 5312. doi:10.1158/1538-7445.AM2013-5312

ATAD5, the human ortholog of yeast Elg1, plays a role in PCNA deubiquitination. Since PCNA modification is important to regulate DNA damage bypass, ATAD5 may be important for suppression of genomic instability in mammals in vivo. To test this hypothesis, we generated heterozygous (Atad5+/m) mice that were haploinsuffficient for Atad5. Atad5+/m mice displayed high levels of genomic instability in vivo, and Atad5+/m mouse embryonic fibroblasts (MEFs) exhibited molecular defects in PCNA deubiquitination in response to DNA damage, as well as DNA damage hypersensitivity and high levels of genomic instability, apoptosis, and aneuploidy. Importantly, 90% of haploinsufficient Atad5+/m mice developed tumors, including sarcomas, carcinomas, and adenocarcinomas, between 11 and 20 months of age. High levels of genomic alterations were evident in tumors that arose in the Atad5+/m mice. Consistent with a role for Atad5 in suppressing tumorigenesis, we also identified somatic mutations of ATAD5 in 4.6% of sporadic human endometrial tumors, including two nonsense mutations that resulted in loss of proper ATAD5 function. Taken together, our findings indicate that loss-of-function mutations in mammalian Atad5 are sufficient to cause genomic instability and tumorigenesis., Author Summary Genomic instability is a hallmark of tumorigenesis, suggesting that mutations in genes suppressing genomic instability contribute to this phenotype. In this study, we demonstrate for the first time that haploinsufficiency for Atad5, a protein that is important in stabilizing stalled DNA replication forks by regulating PCNA ubiquitination during DNA damage bypass, predisposes >90% of mice to tumorigenesis in multiple organs. In heterozygous Atad5 mice, both somatic cells and the spontaneous tumors showed high levels of genomic instability. In a subset of sporadic human endometrial tumors, we identified heterozygous loss-of-function somatic mutations in the ATAD5 gene, consistent with the role of mouse Atad5 in suppressing tumorigenesis. Collectively, our findings suggest that ATAD5 may be a novel tumor suppressor gene.