Showing papers on "BAP1 published in 2011"

Germline BAP1 mutations predispose to malignant mesothelioma

Abstract: Because only a small fraction of asbestos-exposed individuals develop malignant mesothelioma, and because mesothelioma clustering is observed in some families, we searched for genetic predisposing factors. We discovered germline mutations in the gene encoding BRCA1 associated protein-1 (BAP1) in two families with a high incidence of mesothelioma, and we observed somatic alterations affecting BAP1 in familial mesotheliomas, indicating biallelic inactivation. In addition to mesothelioma, some BAP1 mutation carriers developed uveal melanoma. We also found germline BAP1 mutations in 2 of 26 sporadic mesotheliomas; both individuals with mutant BAP1 were previously diagnosed with uveal melanoma. We also observed somatic truncating BAP1 mutations and aberrant BAP1 expression in sporadic mesotheliomas without germline mutations. These results identify a BAP1-related cancer syndrome that is characterized by mesothelioma and uveal melanoma. We hypothesize that other cancers may also be involved and that mesothelioma predominates upon asbestos exposure. These findings will help to identify individuals at high risk of mesothelioma who could be targeted for early intervention.

Germline mutations in BAP1 predispose to melanocytic tumors

Abstract: Common acquired melanocytic nevi are benign neoplasms that are composed of small, uniform melanocytes and are typically present as flat or slightly elevated pigmented lesions on the skin. We describe two families with a new autosomal dominant syndrome characterized by multiple, skin-colored, elevated melanocytic tumors. In contrast to common acquired nevi, the melanocytic neoplasms in affected family members ranged histopathologically from epithelioid nevi to atypical melanocytic proliferations that showed overlapping features with melanoma. Some affected individuals developed uveal or cutaneous melanomas. Segregating with this phenotype, we found inactivating germline mutations of BAP1, which encodes a ubiquitin carboxy-terminal hydrolase. The majority of melanocytic neoplasms lost the remaining wild-type allele of BAP1 by various somatic alterations. In addition, we found BAP1 mutations in a subset of sporadic melanocytic neoplasms showing histological similarities to the familial tumors. These findings suggest that loss of BAP1 is associated with a clinically and morphologically distinct type of melanocytic neoplasm.

The nuclear deubiquitinase BAP1 is commonly inactivated by somatic mutations and 3p21.1 losses in malignant pleural mesothelioma

Abstract: Malignant pleural mesotheliomas (MPMs) often show CDKN2A and NF2 inactivation, but other highly recurrent mutations have not been described. To identify additional driver genes, we used an integrated genomic analysis of 53 MPM tumor samples to guide a focused sequencing effort that uncovered somatic inactivating mutations in BAP1 in 23% of MPMs. The BAP1 nuclear deubiquitinase is known to target histones (together with ASXL1 as a Polycomb repressor subunit) and the HCF1 transcriptional co-factor, and we show that BAP1 knockdown in MPM cell lines affects E2F and Polycomb target genes. These findings implicate transcriptional deregulation in the pathogenesis of MPM.

Germline BAP1 mutation predisposes to uveal melanoma, lung adenocarcinoma, meningioma, and other cancers

Abstract: Objective To investigate the potential contribution of germline sequence alterations in the BAP1 gene in uveal melanoma (UM) patients with possible predisposition to hereditary cancer. Design A total of 53 unrelated UM patients with high risk for hereditary cancer and five additional family members of one proband were studied. Mutational screening was carried out by direct sequencing. Results Of the 53 UM patients studied, a single patient was identified with a germline BAP1 truncating mutation, c. 799 C→T (p.Q267X), which segregated in several family members and was associated with UM and other cancers. Biallelic inactivation of BAP1 and decreased BAP1 expression were identified in the UM, lung adenocarcinoma and meningioma tumours from three family members with this germline BAP1 mutation. Germline BAP1 variants of uncertain significance, likely non-pathogenic, were also identified in two additional UM patients. Conclusion This study reports a novel hereditary cancer syndrome caused by a germline BAP1 mutation that predisposes patients to UM, lung carcinoma, meningioma, and possibly other cancers. The results indicate that BAP1 is the candidate gene in only a small subset of hereditary UM, suggesting the contribution of other candidate genes.

An Emerging Model for BAP1’s Role in Regulating Cell Cycle Progression

Abstract: BRCA1-associated protein-1 (BAP1) is a 729 residue, nuclear-localized deubiquitinating enzyme (DUB) that displays tumor suppressor properties in the BAP1-null NCI-H226 lung carcinoma cell line. Studies that have altered BAP1 cellular levels or enzymatic activity have reported defects in cell cycle progression, notably at the G1/S transition. Recently BAP1 was shown to associate with the transcriptional regulator host cell factor 1 (HCF-1). The BAP1/HCF-1 interaction is mediated by the HCF-1 Kelch domain and an HCF-1 binding motif (HBM) within BAP1. HCF-1 is modified with ubiquitin in vivo, and ectopic studies suggest BAP1 deubiquitinates HCF-1. HCF-1 is a chromatin-associated protein thought to both activate and repress transcription by linking appropriate histone-modifying enzymes to a subset of transcription factors. One known role of HCF-1 is to promote cell cycle progression at the G1/S boundary by recruiting H3K4 histone methyltransferases to the E2F1 transcription factor so that genes required for S-phase can be transcribed. Given the robust associations between BAP1/HCF-1 and HCF-1/E2Fs, it is reasonable to speculate that BAP1 influences cell proliferation at G1/S by co-regulating transcription from HCF-1/E2F-governed promoters

Germline BAP1 mutations and tumor susceptibility.

Abstract: Two new studies describe germline mutations in BAP1 in putatively dissimilar cancer-related syndromes. The spectrum of neoplasms associated with these germline mutations suggest that BAP1 has an important tumor suppressor function in multiple tissues.

Abstract LB-125: Germline mutations in BAP1 predispose to melanocytic nevi and melanoma

Abstract: Proceedings: AACR 102nd Annual Meeting 2011‐‐ Apr 2‐6, 2011; Orlando, FL We describe an autosomal-dominant syndrome characterized by multiple non-pigmented, exophytic melanocytic nevi and an increased susceptibility for melanoma, caused by germline mutations in the histone deubiquitinase BAP1. To identify the causative alterations, we performed comprehensive genomic analyses in two unrelated families with numerous dermal nevi composed largely of large, epithelioid melanocytes with abundant amphophilic cytoplasm and large, pleomorphic, vesicular nuclei with prominent nucleoli. Both families each had one proband with uveal melanoma, and three probands in one family had cutaneous melanoma. Array-based comparative genomic hybridization (aCGH) revealed losses of parts of or the entire chromosome 3 in 11 of 22 neoplasms studied. Genotypic analyses revealed that the deletions invariably affected the chromosome from the unaffected parent. Genome partitioning of the minimally deleted region on chromosome 3p21 followed by massively parallel sequencing revealed two different inactivating germline mutations of the BAP1 tumor suppressor gene that in both families segregated with the phenotype. In almost all tumors the remaining wild type BAP1 allele was eliminated by deletion, separate inactivating mutations, or loss of heterozygosity. 35 of 40 nevi (88%) showed mutations in BRAF, while the uveal melanomas had mutations in GNAQ. Our data identify BAP1 as a highly penetrant susceptibility gene for melanocytic neoplasia. Somatic BAP1 mutations have recently been reported in uveal melanoma and linked to the metastatic phenotype. Our observation of frequent bi-allelic inactivation of BAP1 in nevi indicates that the role of BAP1 in melanocytic neoplasia is more complex, and may differ depending on other factors such as the type of melanocyte (uveal or cutaneous) and the co-existing oncogenic mutation. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr LB-125. doi:10.1158/1538-7445.AM2011-LB-125