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Li D, Harlan-Williams LM, Kumaraswamy E, Jensen RA. BRCA1-No Matter How You Splice It. Cancer Res 2019; 79:2091-2098. [PMID: 30992324 PMCID: PMC6497576 DOI: 10.1158/0008-5472.can-18-3190] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Revised: 02/09/2019] [Accepted: 03/05/2019] [Indexed: 02/07/2023]
Abstract
BRCA1 (breast cancer 1, early onset), a well-known breast cancer susceptibility gene, is a highly alternatively spliced gene. BRCA1 alternative splicing may serve as an alternative regulatory mechanism for the inactivation of the BRCA1 gene in both hereditary and sporadic breast cancers, and other BRCA1-associated cancers. The alternative transcripts of BRCA1 can mimic known functions, possess unique functions compared with the full-length BRCA1 transcript, and in some cases, appear to function in opposition to full-length BRCA1 In this review, we will summarize the functional "naturally occurring" alternative splicing transcripts of BRCA1 and then discuss the latest next-generation sequencing-based detection methods and techniques to detect alternative BRCA1 splicing patterns and their potential use in cancer diagnosis, prognosis, and therapy.
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Affiliation(s)
- Dan Li
- The University of Kansas Cancer Center, Kansas City, Kansas
| | - Lisa M Harlan-Williams
- The University of Kansas Cancer Center, Kansas City, Kansas
- Department of Anatomy and Cell Biology, University of Kansas Medical Center, Kansas City, Kansas
| | - Easwari Kumaraswamy
- The University of Kansas Cancer Center, Kansas City, Kansas
- Department of Pathology and Laboratory Medicine, University of Kansas Medical Center, Kansas City, Kansas
| | - Roy A Jensen
- The University of Kansas Cancer Center, Kansas City, Kansas.
- Department of Anatomy and Cell Biology, University of Kansas Medical Center, Kansas City, Kansas
- Department of Pathology and Laboratory Medicine, University of Kansas Medical Center, Kansas City, Kansas
- Department of Cancer Biology, University of Kansas Medical Center, Kansas City, Kansas
- Department of Molecular Biosciences, University of Kansas, Lawrence, Kansas
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Harte MT, Gorski JJ, Savage KI, Purcell JW, Barros EM, Burn PM, McFarlane C, Mullan PB, Kennedy RD, Perkins ND, Harkin DP. NF-κB is a critical mediator of BRCA1-induced chemoresistance. Oncogene 2013; 33:713-723. [PMID: 23435429 PMCID: PMC3917825 DOI: 10.1038/onc.2013.10] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/26/2012] [Revised: 12/13/2012] [Accepted: 12/14/2012] [Indexed: 12/17/2022]
Abstract
BRCA1 mediates resistance to apoptosis in response to DNA damaging agents, causing BRCA1 wild-type tumours to be significantly more resistant to DNA damage than their mutant counterparts. In this study we demonstrate that following treatment with the DNA damaging agents etoposide or camptothecin, BRCA1 is required for the activation of NF-κB, and that BRCA1 and NF-κB cooperate to regulate the expression of the NF-κB antiapoptotic targets BCL2 and XIAP. We show that BRCA1 and the NF-κB subunit p65/RelA associate constitutively, whereas the p50 NF-κB subunit associates with BRCA1 only upon DNA damage treatment. Consistent with this BRCA1 and p65 are present constitutively on the promoters of BCL2 and XIAP whereas p50 is recruited to these promoters only in damage treated cells. Importantly, we demonstrate that the recruitment of p50 onto the promoters of BCL2 and XIAP is dependent upon BRCA1, but independent of its NF-κB partner subunit p65. The functional relevance of NF-κB activation by BRCA1 in response to etoposide and camptothecin is demonstrated by the significantly reduced survival of BRCA1 wild type cells upon NF-κB inhibition. This study identifies a novel BRCA1-p50 complex, and demonstrates for the first time that NF-κB is required for BRCA1 mediated resistance to DNA damage. It reveals a functional interdependence between BRCA1 and NF-κB, further elucidating the role played by NF-κB in mediating cellular resistance of BRCA1 wild-type tumours to DNA damaging agents.
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Affiliation(s)
- Mary T Harte
- Centre for Cancer Research and Cell Biology, Queen's University Belfast, 97 Lisburn Road, Belfast, Northern Ireland, UK BT9 7BL
| | - Julia J Gorski
- Centre for Cancer Research and Cell Biology, Queen's University Belfast, 97 Lisburn Road, Belfast, Northern Ireland, UK BT9 7BL
| | - Kienan I Savage
- Centre for Cancer Research and Cell Biology, Queen's University Belfast, 97 Lisburn Road, Belfast, Northern Ireland, UK BT9 7BL
| | | | - Eliana M Barros
- Centre for Cancer Research and Cell Biology, Queen's University Belfast, 97 Lisburn Road, Belfast, Northern Ireland, UK BT9 7BL
| | - Philip M Burn
- Centre for Cancer Research and Cell Biology, Queen's University Belfast, 97 Lisburn Road, Belfast, Northern Ireland, UK BT9 7BL
| | - Cheryl McFarlane
- Centre for Cancer Research and Cell Biology, Queen's University Belfast, 97 Lisburn Road, Belfast, Northern Ireland, UK BT9 7BL
| | - Paul B Mullan
- Centre for Cancer Research and Cell Biology, Queen's University Belfast, 97 Lisburn Road, Belfast, Northern Ireland, UK BT9 7BL
| | - Richard D Kennedy
- Centre for Cancer Research and Cell Biology, Queen's University Belfast, 97 Lisburn Road, Belfast, Northern Ireland, UK BT9 7BL
| | | | - D Paul Harkin
- Centre for Cancer Research and Cell Biology, Queen's University Belfast, 97 Lisburn Road, Belfast, Northern Ireland, UK BT9 7BL
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BRCA1 exon 11 alternative splicing, multiple functions and the association with cancer. Biochem Soc Trans 2012; 40:768-72. [PMID: 22817731 DOI: 10.1042/bst20120140] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
BRCA1 (breast cancer early-onset 1) alternative splicing levels are regulated in a cell-cycle- and cell-type-specific manner, with splice variants being present in different proportions in tumour cell lines as well as in normal mammary epithelial cells. The importance of this difference in the pathogenesis of breast cancer has yet to be determined. Developing an understanding of the impact of BRCA1 isoform ratio changes on cell phenotype will be of value in breast cancer and may offer therapeutic options. In the present paper, we describe the splicing isoforms of BRCA1 exon 11, their possible role in cancer biology and the importance of maintaining a balanced ratio.
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BRCA1 185delAG truncation protein, BRAt, amplifies caspase-mediated apoptosis in ovarian cells. In Vitro Cell Dev Biol Anim 2008; 44:357-67. [DOI: 10.1007/s11626-008-9122-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2008] [Accepted: 05/08/2008] [Indexed: 01/11/2023]
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Hasegawa Y, Fukuda S, Shimokawa K, Kondo S, Maeda N, Hayashizaki Y. A RecA-mediated exon profiling method. Nucleic Acids Res 2006; 34:e97. [PMID: 16896013 PMCID: PMC1540731 DOI: 10.1093/nar/gkl497] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022] Open
Abstract
We have developed a RecA-mediated simple, rapid and scalable method for identifying novel alternatively spliced full-length cDNA candidates. This method is based on the principle that RecA proteins allow to carry radioisotope-labeled probe DNAs to their homologous sequences, resulting in forming triplexes. The resulting complex is easily detected by mobility difference on electrophoresis. We applied this exon profiling method to four selected mouse genes as a feasibility study. To design probes for detection, the information on known exonic regions was extracted from public database, RefSeq. Concerning the potentially transcribed novel exonic regions, RNA mapping experiment using Affymetrix tiling array was performed. As a result, we were able to identify alternative splice variants of Thioredoxin domain containing 5, Interleukin1β, Interleukin 1 family 6 and glutamine-rich hypothetical protein. In addition, full-length sequencing demonstrated that our method could profile exon structures with >90% accuracy. This reliable method can allow us to screen novel splice variants from a huge number of cDNA clone set effectively.
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Affiliation(s)
- Yuki Hasegawa
- Genome Exploration Research Group, RIKEN Genomic Sciences Center (GSC), RIKEN Yokohama Institute 1-7-22 Suehiro-choTsurumi-ku, Yokohama, Kanagawa 230-0045, Japan
- International Graduate School of Arts and Sciences, Yokohama City University1-7-29 Suehiro-Cho, Tsurumi-Ku, Yokohama 230-0045, Japan
| | - Shiro Fukuda
- Genome Exploration Research Group, RIKEN Genomic Sciences Center (GSC), RIKEN Yokohama Institute 1-7-22 Suehiro-choTsurumi-ku, Yokohama, Kanagawa 230-0045, Japan
| | - Kazuro Shimokawa
- Genome Exploration Research Group, RIKEN Genomic Sciences Center (GSC), RIKEN Yokohama Institute 1-7-22 Suehiro-choTsurumi-ku, Yokohama, Kanagawa 230-0045, Japan
| | - Shinji Kondo
- Genome Exploration Research Group, RIKEN Genomic Sciences Center (GSC), RIKEN Yokohama Institute 1-7-22 Suehiro-choTsurumi-ku, Yokohama, Kanagawa 230-0045, Japan
| | - Norihiro Maeda
- Genome Science Laboratory, Discovery and Research InstituteRIKEN Wako Main Campus, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
| | - Yoshihide Hayashizaki
- Genome Exploration Research Group, RIKEN Genomic Sciences Center (GSC), RIKEN Yokohama Institute 1-7-22 Suehiro-choTsurumi-ku, Yokohama, Kanagawa 230-0045, Japan
- International Graduate School of Arts and Sciences, Yokohama City University1-7-29 Suehiro-Cho, Tsurumi-Ku, Yokohama 230-0045, Japan
- Genome Science Laboratory, Discovery and Research InstituteRIKEN Wako Main Campus, 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
- To whom correspondence should be addressed. Tel: +81 45 503 9222; Fax: +81 45 503 9216;
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Honrado E, Benítez J, Palacios J. The molecular pathology of hereditary breast cancer: genetic testing and therapeutic implications. Mod Pathol 2005; 18:1305-20. [PMID: 15933754 DOI: 10.1038/modpathol.3800453] [Citation(s) in RCA: 125] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Abstract
Cancer arising in carriers of mutations in the BRCA1 and BRCA2 genes differs from sporadic breast cancer of age-matched controls and from non-BRCA1/2 familial breast carcinomas in its morphological, immunophenotypic and molecular characteristics. Most BRCA1 carcinomas have the basal cell phenotype, a subtype of high-grade, highly proliferating, estrogen receptor- and HER2-negative breast carcinomas, characterized by the expression of basal or myoepithelial markers such as basal keratins, P-cadherin, epidermal growth factor receptor, etc. This phenotype is rarely found in BRCA2 carcinomas, which are of higher grade than sporadic age-matched controls, but tend to be estrogen receptor- and progesterone receptor-positive. The expression of the cell-cycle proteins cyclins A, B1 and E and SKP2 is associated with a BRCA1 phenotype, whereas cyclin D1 and p27 expression is associated with BRCA2 carcinomas. Recent studies have shown that hereditary carcinomas that are not attributable to BRCA1/2 mutations have phenotypic similarities to BRCA2 tumors, but tend to be of lower grade and proliferation index. Somatic mutations in the BRCA genes are rarely found in hereditary tumors; by contrast, BRCA1 and BRCA2 loss of heterozygosity (LOH) is found in almost all BRCA1 and BRCA2 carcinomas, respectively. Furthermore, all types of hereditary breast carcinomas have a low frequency of HER2 expression. Finally, comparative genomic hybridization studies have revealed differences in chromosomal gains and losses between genotypes. The pathological and molecular features of hereditary breast cancer can drive specific treatments and influence the process of mutation screening. In addition, detecting molecular changes such as BRCA1/2 LOH in nonatypical cells obtained by random fine-needle aspiration, ductal lavage or nipple aspirate fluid may help to earlier identify carrier women who are at an even higher risk of developing breast carcinoma.
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Affiliation(s)
- Emiliano Honrado
- Human Genetics Department, Centro Nacional de Investigaciones Oncológicas (CNIO), Madrid, Spain
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Abstract
Germline mutations of the BRCA1 gene predispose individuals mainly to the development of breast and/or ovarian cancer. However, the exact function of the gene is still unclear, although the encoded proteins are involved in various cellular processes, including transcriptional regulation and DNA repair pathways. Several BRCA1 splice variants are found in different tissues, but in spite of intense investigations, their regulation and possible functions are poorly understood at the moment. This review summarises current knowledge on the roles of these splice variants and the mechanisms responsible for their formation. Because alternative splicing is now widely accepted as an important source of genetic diversity, elucidating the functions of the BRCA1 splice variants would help in the understanding of the exact role(s) of this tumour suppressor. This should help to resolve the current paradox that, despite its seemingly vital cellular functions, mutations of this gene are associated with tissue specific tumour formation predominantly in the breast and the ovary.
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Affiliation(s)
- T I Orban
- National Institute of Oncology, Department of Molecular Genetics, Budapest, H-1122, Hungary.
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