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Chehade R, Pettapiece-Phillips R, Salmena L, Kotlyar M, Jurisica I, Narod SA, Akbari MR, Kotsopoulos J. Reduced BRCA1 transcript levels in freshly isolated blood leukocytes from BRCA1 mutation carriers is mutation specific. Breast Cancer Res 2016; 18:87. [PMID: 27534398 PMCID: PMC4989508 DOI: 10.1186/s13058-016-0739-8] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2015] [Accepted: 07/22/2016] [Indexed: 01/07/2023] Open
Abstract
Background BRCA1 mutation carriers face a high lifetime risk of developing both breast and ovarian cancer. Haploinsufficiency is thought to predispose these women to cancer by reducing the pool of available BRCA1 transcript and protein, thereby compromising BRCA1 function. Whether or not cancer-free BRCA1 mutation carriers have lower messenger (m)RNA transcript levels in peripheral blood leukocytes has not been evaluated. The primary aim of this study was to characterize an association between BRCA1 mutation status and BRCA1 mRNA leukocyte expression levels among healthy women with a BRCA1 mutation. Method RNA was extracted from freshly isolated peripheral blood leukocytes of 58 cancer-free, female participants (22 BRCA1 mutation carriers and 36 non-carriers). The expression levels of 236 cancer-associated genes, including BRCA1, were quantified using the Human Cancer Reference gene panel from the Nanostring Technologies nCounter Analysis System. Results Multivariate modeling demonstrated that carrying a BRCA1 mutation was the most significant predictor of BRCA1 mRNA levels. BRCA1 mRNA levels were significantly lower in BRCA1 mutation carriers compared to non-carriers (146.7 counts vs. 175.1 counts; P = 0.002). Samples with BRCA1 mutations within exon 11 had lower BRCA1 mRNA levels than samples with mutations within the 5′ and 3′ regions of the BRCA1 gene (122.1 counts vs. 138.9 and 168.6 counts, respectively; P = 0.003). Unsupervised hierarchical clustering of gene expression profiles from freshly isolated blood leukocytes revealed that BRCA1 mutation carriers cluster more closely with other BRCA1 mutation carriers than with BRCA1 wild-type samples. Moreover, a set of 17 genes (including BRCA1) previously shown to be involved in carcinogenesis, were differentially expressed between BRCA1 mutation carriers and non-carriers. Conclusion Overall, these findings support the concept of BRCA1 haploinsufficiency wherein a specific mutation results in dosage-dependent alteration of BRCA1 at the transcriptional level. This study is the first to show a decrease in BRCA1 mRNA expression in freshly isolated blood leukocytes from healthy, unaffected BRCA1 mutation carriers. Electronic supplementary material The online version of this article (doi:10.1186/s13058-016-0739-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Rania Chehade
- Women's College Research Institute, Women's College Hospital, 76 Grenville Street, 6th Floor, Toronto, ON, Canada.,Faculty of Medicine and Dentistry, University of Alberta, 2J2.00 WC Mackenzie Health Sciences Centre, Edmonton, AB, Canada
| | - Rachael Pettapiece-Phillips
- Women's College Research Institute, Women's College Hospital, 76 Grenville Street, 6th Floor, Toronto, ON, Canada.,Department of Nutritional Sciences, University of Toronto, FitzGerald Building, 150 College Street, Room 316, Toronto, ON, Canada
| | - Leonardo Salmena
- Princess Margaret Cancer Centre, University Health Network, Toronto, ON, Canada.,Department of Pharmacology and Toxicology, University of Toronto, Toronto, ON, Canada
| | - Max Kotlyar
- Princess Margaret Cancer Centre, University Health Network, Toronto, ON, Canada
| | - Igor Jurisica
- Princess Margaret Cancer Centre, University Health Network, Toronto, ON, Canada.,Department of Medical Biophysics and Computer Science, University of Toronto, Toronto, ON, Canada
| | - Steven A Narod
- Women's College Research Institute, Women's College Hospital, 76 Grenville Street, 6th Floor, Toronto, ON, Canada.,Department of Nutritional Sciences, University of Toronto, FitzGerald Building, 150 College Street, Room 316, Toronto, ON, Canada.,Dalla Lana School of Public Health, University of Toronto, 155 College Street Health Science Building, 6th Floor, Toronto, ON, Canada
| | - Mohammad R Akbari
- Women's College Research Institute, Women's College Hospital, 76 Grenville Street, 6th Floor, Toronto, ON, Canada.,Dalla Lana School of Public Health, University of Toronto, 155 College Street Health Science Building, 6th Floor, Toronto, ON, Canada
| | - Joanne Kotsopoulos
- Women's College Research Institute, Women's College Hospital, 76 Grenville Street, 6th Floor, Toronto, ON, Canada. .,Department of Nutritional Sciences, University of Toronto, FitzGerald Building, 150 College Street, Room 316, Toronto, ON, Canada. .,Dalla Lana School of Public Health, University of Toronto, 155 College Street Health Science Building, 6th Floor, Toronto, ON, Canada.
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2
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Weberpals JI, Tu D, Squire JA, Amin MS, Islam S, Pelletier LB, O'Brien AM, Hoskins PJ, Eisenhauer EA. Breast cancer 1 (BRCA1) protein expression as a prognostic marker in sporadic epithelial ovarian carcinoma: an NCIC CTG OV.16 correlative study. Ann Oncol 2011; 22:2403-2410. [PMID: 21368065 DOI: 10.1093/annonc/mdq770] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
BACKGROUND Breast cancer 1 (BRCA1) protein inactivation in sporadic ovarian carcinoma (OC) is common and low BRCA1 expression is linked with platinum sensitivity. The clinical validation of BRCA1 as a prognostic marker in OC remains unresolved. PATIENTS AND METHODS In 251 patient samples from the NCIC CTG clinical trial, OV.16, BRCA1 protein expression was determined by immunohistochemistry. RESULTS For all patients, when BRCA1 score was analyzed as a continuous variable, there was no significant correlation between BRCA1 protein expression and progression-free survival (PFS) [adjusted hazard ratio (HR) = 1.15 (0.96-1.37), P = 0.12] or response rate [HR = 0.89 (0.70-1.12), P = 0.32]. In the 116 patients with minimal residual disease (RD), higher BRCA1 expression correlated significantly with worse PFS [HR = 1.40 (1.04-1.89), P = 0.03]. Subgroup analysis divided patients with minimal RD into low (BRCA1 ≤2.5) and high (BRCA1 >2.5) expression groups. Patients with low BRCA1 expression had a more favorable outcome [median PFS was 24.7 and 16.6 months in patients with low and high BRCA1, respectively; HR = 0.56 (0.35-0.89), P = 0.01]. CONCLUSIONS This study suggests that BRCA1 protein is a prognostic marker in sporadic OC patients with minimal RD. Further research is needed to evaluate BRCA1 as a predictive biomarker and to target BRCA1 expression to enhance chemotherapeutic sensitivity.
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Affiliation(s)
- J I Weberpals
- Centre for Cancer Therapeutics, Ottawa Hospital Research Institute; The Division of Gynaecologic Oncology, The Ottawa Hospital, Ottawa.
| | - D Tu
- The NCIC Clinical Trials Group, Kingston
| | - J A Squire
- The NCIC Clinical Trials Group, Kingston
| | - M S Amin
- The Department of Pathology and Laboratory Medicine, The Ottawa Hospital, Ottawa
| | - S Islam
- The Department of Pathology and Laboratory Medicine, The Ottawa Hospital, Ottawa
| | - L B Pelletier
- The Department of Pathology and Laboratory Medicine, The Ottawa Hospital, Ottawa
| | - A M O'Brien
- Centre for Cancer Therapeutics, Ottawa Hospital Research Institute
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3
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Moreau K, Dizin E, Ray H, Luquain C, Lefai E, Foufelle F, Billaud M, Lenoir GM, Venezia ND. BRCA1 affects lipid synthesis through its interaction with acetyl-CoA carboxylase. J Biol Chem 2005; 281:3172-81. [PMID: 16326698 DOI: 10.1074/jbc.m504652200] [Citation(s) in RCA: 97] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Germ line alterations in BRCA1 (breast cancer susceptibility gene 1) are associated with an increased susceptibility to breast and ovarian cancer. BRCA1 acts as a scaffold protein implicated in multiple cellular functions, such as transcription, DNA repair, and ubiquitination. However, the molecular mechanisms responsible for tumorigenesis are not yet fully understood. We have recently demonstrated that BRCA1 interacts in vivo with acetyl coenzyme A carboxylase alpha (ACCA) through its tandem of BRCA1 C terminus (BRCT) domains. To understand the biological function of the BRCA1.ACCA complex, we sought to determine whether BRCA1 is a regulator of lipogenesis through its interaction with ACCA. We showed here that RNA inhibition-mediated down-regulation of BRCA1 expression induced a marked increase in the fatty acid synthesis. We then delineated the biochemical characteristics of the complex and found that BRCA1 interacts solely with the phosphorylated and inactive form of ACCA (P-ACCA). Finally, we demonstrated that BRCA1 affects lipid synthesis by preventing P-ACCA dephosphorylation. These results suggest that BRCA1 affects lipogenesis through binding to P-ACCA, providing a new mechanism by which BRCA1 may exert a tumor suppressor function.
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Affiliation(s)
- Karen Moreau
- CNRS UMR 5201, Laboratoire de Génétique Moléculaire, Signalisation et Cancer, Faculté deMédecine Rockefeller, 69373 Lyon cedex 08, France
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4
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Auriol E, Billard LM, Magdinier F, Dante R. Specific binding of the methyl binding domain protein 2 at the BRCA1-NBR2 locus. Nucleic Acids Res 2005; 33:4243-54. [PMID: 16052033 PMCID: PMC1181861 DOI: 10.1093/nar/gki729] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The methyl-CpG binding domain (MBD) proteins are key molecules in the interpretation of DNA methylation signals leading to gene silencing. We investigated their binding specificity at the constitutively methylated region of a CpG island containing the bidirectional promoter of the Breast cancer predisposition gene 1, BRCA1, and the Near BRCA1 2 (NBR2) gene. In HeLa cells, quantitative chromatin immunoprecipitation assays indicated that MBD2 is associated with the methylated region, while MeCP2 and MBD1 were not detected at this locus. MBD2 depletion (∼90%), mediated by a transgene expressing a small interfering RNA (siRNA), did not induce MeCP2 or MBD1 binding at the methylated area. Furthermore, the lack of MBD2 at the BRCA1-NBR2 CpG island is associated with an elevated level of NBR2 transcripts and with a significant reduction of induced-DNA-hypomethylation response. In MBD2 knockdown cells, transient expression of a Mbd2 cDNA, refractory to siRNA-mediated decay, shifted down the NBR2 mRNA level to that observed in unmodified HeLa cells. Variations in MBD2 levels did not affect BRCA1 expression despite its stimulation by DNA hypomethylation. Collectively, our data indicate that MBD2 has specific targets and its presence at these targets is indispensable for gene repression.
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Affiliation(s)
| | | | | | - Robert Dante
- To whom correspondence should be addressed. Tel: +33 4 78 78 59 22; Fax: +33 4 78 78 27 20;
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5
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Misiewicz I, Kozar A, Skupinska K, Kowalska E, Lubinski J, Kasprzycka-Guttman T. Inhibition of cell cycle and induction of apoptosis by 2-oxoheksyl isothiocyanate and alyssin in cell lines carrying various inheritedBRCA1 mutations. Drug Dev Res 2005. [DOI: 10.1002/ddr.20007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
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6
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Trenz K, Landgraf J, Speit G. Mutagen sensitivity of human lymphoblastoid cells with a BRCA1 mutation. Breast Cancer Res Treat 2003; 78:69-79. [PMID: 12611459 DOI: 10.1023/a:1022157528247] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Previous results indicated that lymphoblastoid cell lines (LCL) with a BRCA1 mutation are hypersensitive to the chromosome-damaging effects of gamma irradiation or hydrogen peroxide as revealed by the micronucleus test. We now investigated six LCL (three with and three without a BRCA1 mutation) in more detail, to see whether LCL represent a useful model for the investigation of mechanisms responsible for the known mutagen sensitivity of lymphocytes from women carrying a BRCA1 mutation. Our results show that there is no systematic difference in radiation sensitivity between LCL with and without a BRCA1 mutation. Spontaneous and gamma radiation-induced micronucleus frequencies were in same range. Furthermore, cytotoxic effects (reduced cell proliferation, reduced viability) induced by gamma radiation were not different. The only difference found was an induction of micronuclei by 10 microM hydrogen peroxide in BRCA1 cell lines while a concentration of 20 microM hydrogen peroxide was necessary to induce micronuclei in control cells. Comet assay experiments did not reveal differences with regard to the induction and removal of primary DNA damage. Furthermore, expression of BRCA1 mRNA after gamma irradiation showed considerable variability and there was no clear difference between cell lines with and without BRCA mutation. These results indicate that LCL with a BRCA1 mutation do not generally show the same mutagen sensitivity as lymphocytes with the same BRCA1 mutation. Therefore, the use of LCL to study the mechanisms underlying mutagen sensitivity due to a heterozygous BRCA1 mutation seems to be limited.
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Affiliation(s)
- Kristina Trenz
- Universitätsklinikum Ulm, Abteilung Humangenetik, Ulm, Germany
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7
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Billard LM, Magdinier F, Lenoir GM, Frappart L, Dante R. MeCP2 and MBD2 expression during normal and pathological growth of the human mammary gland. Oncogene 2002; 21:2704-12. [PMID: 11965543 DOI: 10.1038/sj.onc.1205357] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2001] [Revised: 01/21/2002] [Accepted: 01/22/2002] [Indexed: 11/09/2022]
Abstract
During the last years, a direct link between DNA methylation and repressive chromatin structure has been established. This structural modification is mediated by histone deacetylases targeted to the methylated sequences by Methyl Binding Proteins (MBD). Human cancer cells exhibit both a global hypomethylation and some localized hypermethylations suggesting that the deregulation of the methylation machinery is a central event in tumorigenesis. Therefore, we have investigated in human tissues the expression of two major MBDs, MeCP2 and MBD2, during the proliferation of normal breast and in benign and neoplasic breast tumors. Quantitation of the transcripts indicates that MBD2 mRNAs are 20-30-fold more abundant than MeCP2 transcripts in the adult and fetal human mammary gland. In pathological tissues samples MBD2 mRNA levels are significantly higher (P=0.001) in benign tumors compared with normal breast tissues, whereas MeCP2 expression is not modified in these specimens. In neoplasic samples a deregulation of the expression of both genes was found. The amounts of MBD2 and MeCP2 transcripts vary greatly between samples in cancer cells compared to normal breast tissues or benign tumors, and in invasive ductal carcinomas the amount of MBD2 mRNA is significantly (P=0.03) associated with the tumor size. Taken together these data suggest that upregulation of MBD2 might be associated with breast cell proliferation. In line with this hypothesis MBD2 is also upregulated during the prenatal development of the human mammary gland, but in contrast to that observed in tumor cells, MeCP2 is also coordinately upregulated in the fetal breast tissues, suggesting that deregulation of MeCP2 and MBD2 occurs in human breast cancers.
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Affiliation(s)
- Lise-Marie Billard
- Laboratoire de Génétique, UMR 5641 CNRS, UCBL1, 8 avenue Rockefeller, 69373 Lyon cedex 08, France
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8
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Pérez-Vallés A, Martorell-Cebollada M, Nogueira-Vázquez E, García-García JA, Fuster-Diana E. The usefulness of antibodies to the BRCA1 protein in detecting the mutated BRCA1 gene. An immunohistochemical study. J Clin Pathol 2001; 54:476-80. [PMID: 11376024 PMCID: PMC1731451 DOI: 10.1136/jcp.54.6.476] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
AIM To assess the value of immunohistochemistry in discriminating between BRCA1 associated and non-BRCA1 associated breast tumours. METHODS Four commercially available anti-BRCA1 antibodies were used on 45 paraffin wax embedded tumoral samples from patients with (seven of 45) and without (38 of 45) BRCA1 germline mutations. In all patients, the BRCA1 gene had been studied previously by means of the protein truncation test (PTT), conformational sensitive gel electrophoresis (CSGE), and direct sequencing of genomic DNA. Immunohistochemistry was carried out using the standard avidin-biotin immunoperoxidase method. Antigen retrieval was carried out by means of microwave pretreatment or autoclaving. The antibody panel used comprised D-20 (1/500), I-20 (1/100), K-18 (1/100), and MS110 (Ab-1; 1/50). RESULTS No immunohistochemical differences in BRCA1 protein expression were found between cases with and without BRCA1 germline mutations. All positive cases showed predominantly cytoplasmic staining, in both tumoral and non-tumoral cells, with the polyclonal antibodies D-20, I-20, and K-18. After heating pretreatment both nuclear and cytoplasmic staining were found in tumoral and non-tumoral cells with the I-20 antibody. Only the monoclonal antibody MS110 showed a predominantly nuclear staining after microwave oven treatment. CONCLUSIONS Commercially available BRCA1 antibodies lack the specificity required to identify the BRCA1 protein and thus are not useful for establishing differences between familial and sporadic breast tumours, or between BRCA1 associated and non-BRCA1 associated breast tumours.
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Affiliation(s)
- A Pérez-Vallés
- Department of Pathology, Hospital General Universitario, Avda. Tres Cruces, s/n, 46014 Valencia, Spain.
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9
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Magdinier F, Billard L, Wittmann G, Frappart L, Benchaïb M, Lenoir GM, Guérin JF, Dante R. Regional methylation of the 5’ end CpG island of
BRCA1
is associated with reduced gene expression in human somatic cells. FASEB J 2000. [DOI: 10.1096/fj.99-0817com] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
| | | | - Gaélle Wittmann
- Laboratoire de GénétiqueUMR 5641 CNRS, UCBL169373Lyon cedex08France
| | - Lucien Frappart
- Laboratoire de GénétiqueUMR 5641 CNRS, UCBL169373Lyon cedex08France
| | - Mehdi Benchaïb
- Laboratoire de Biologie de la Reproduction et du DeveloppementUCBL169373Lyon cedex08France
| | | | - Jean François Guérin
- Laboratoire de Biologie de la Reproduction et du DeveloppementUCBL169373Lyon cedex08France
| | - Robert Dante
- Laboratoire de GénétiqueUMR 5641 CNRS, UCBL169373Lyon cedex08France
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10
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Favy DA, Lafarge S, Rio P, Vissac C, Bignon YJ, Bernard-Gallon D. Real-time PCR quantification of full-length and exon 11 spliced BRCA1 transcripts in human breast cancer cell lines. Biochem Biophys Res Commun 2000; 274:73-8. [PMID: 10903898 DOI: 10.1006/bbrc.2000.3100] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Germline alterations of the BRCA1 tumor suppressor gene have been implicated at least in half of familial breast cancers. Nevertheless, in sporadic breast cancer no mutation of this gene has been characterized to date. In sporadic breast tumors, other BRCA1 gene loss of function mechanisms, such as down-regulation of gene expression, have been suggested. In an effort to better understand the relationship between BRCA1 expression and malignant transformation, we have adapted the new real-time quantitative PCR method based on a 5' nuclease assay and the use of doubly labeled fluorescent TaqMan probes to quantify BRCA1 mRNA. We have compared expression of BRCA1 mRNA with or without exon 11 in the normal breast epithelial cell line MCF10a and in three cancer cell lines (MCF-7, MDA-MB231 and HBL100) by comparing two methods of quantification: the comparative C(T) and the standard curve. We found that the full length BRCA1 mRNA, which encodes the functional nuclear protein, was down-regulated in tumor cells when compared with MCF10a cells.
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Affiliation(s)
- D A Favy
- Laboratoire d'Oncologie Moléculaire, EA 2145, Centre Jean Perrin, 58, rue Montalembert B.P.392, Clermont-Ferrand Cedex1, 63011, France
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11
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Annab LA, Terry L, Cable PL, Brady J, Stampfer MR, Barrett JC, Afshari CA. Establishment and characterization of a breast cell strain containing a BRCA1 185delAG mutation. Gynecol Oncol 2000; 77:121-8. [PMID: 10739701 DOI: 10.1006/gyno.2000.5734] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Abstract
OBJECTIVE The aim of this study was to examine whether cells containing the heterozygous form of a BRCA1 185delAG mutation would exhibit abnormal growth or an altered response to DNA damage. METHODS A primary culture of human mammary epithelial cells (90P) was obtained from the nontumor breast tissue of a 35-year-old patient who had undergone a mastectomy for removal of a breast tumor. These cells were immortalized (90PE6E7) following retroviral infection with HPV-16 viral E6/E7. genes. Both the 90P cell strain and the cell line were characterized for their ability to grow in culture, form colonies in soft agar, and produce tumors in athymic nude mice compared to normal breast epithelial cells containing wild-type BRCA1. 90P cells were also analyzed for cellular response to gamma radiation and H(2)O(2). RESULTS These cells were confirmed to contain a frameshift mutation, 185delAG, of the BRCA1 gene. Despite being heterozygous for wild-type BRCA1, the 220-kDa full-size BRCA1 protein was abundantly expressed. 90P and 90PE6E7 cells grew at a similar rate and were anchorage dependent. 90PE6E7 also failed to form tumors in athymic nude mice. Finally, 90P cells exhibited a survival response similar to that of normal mammary epithelial cells to radiation damage and exposure to oxidative stress. CONCLUSION To our knowledge the 90P cells and the 90PE6E7 cells are the first characterized, non-tumor-derived breast epithelial cells that are heterozygous for the BRCA1 germline mutation 185delAG. Our conclusion is that these BRCA1 mutant cells appear to have growth and stress response characteristics similar to those of normal human breast cells, which is consistent with the hypothesis that loss of heterozygosity must occur to impair putative BRCA1 function.
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Affiliation(s)
- L A Annab
- Laboratory of Molecular Carcinogenesis, National Institute of Environmental Health Sciences, Research Triangle Park, North Carolina 27709, USA.
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12
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Magdinier F, Dalla Venezia N, Lenoir GM, Frappart L, Dante R. BRCA1 expression during prenatal development of the human mammary gland. Oncogene 1999; 18:4039-43. [PMID: 10435628 DOI: 10.1038/sj.onc.1202780] [Citation(s) in RCA: 20] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
Germ-line alterations of BRCA1 are associated with elevated risk of breast cancer. Evidence for the involvement of Brca1 in cellular differentiation and morphogenesis has been obtained in mouse models during embryogenesis. Although the presence of well-conserved functional domains might suggest a similar function for both human and mouse genes, very few data on BRCA1 expression in human fetal tissues are available. We have, therefore, investigated the expression of BRCA1 in the mammary gland from human female fetuses aged between 15 and 33 weeks. Quantification of BRCA1 transcripts, using a competitive reverse transcriptase PCR method, indicates a progressive decrease in BRCA1 expression with increasing fetal age between the 15th and 30th week of gestation. Subsequently, the amount of BRCA1 transcripts becomes similar to that found in adult mammary gland. Analysis of BRCA1 protein revealed, in fetal samples, a 220 kDa band corresponding to the 220 kDa BRCA1 protein described in human cell lines. These later experiments confirm that the relative level of the 220 kDa BRCA1 protein is highest in the early stages of mammary gland development. The temporal patterns of BRCA1 expression in human fetuses suggest a role for BRCA1 in the morphogenesis and differentiation of the human mammary gland.
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Affiliation(s)
- F Magdinier
- Laboratoire de Génétique, UMR 5641 CNRS, UCBL1, Lyon, France
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13
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Favy DA, Rio P, Maurizis JC, Hizel C, Bignon YJ, Bernard-Gallon DJ. Prolactin-dependent up-regulation of BRCA1 expression in human breast cancer cell lines. Biochem Biophys Res Commun 1999; 258:284-91. [PMID: 10329379 DOI: 10.1006/bbrc.1999.0602] [Citation(s) in RCA: 23] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
We report experimental evidence that BRCA1, a breast and ovarian cancer susceptibility gene, is up-regulated in response to prolactin (PRL) stimulation. Expression of the BRCA1 gene was monitored in 2 human breast cancer cell lines (MCF-7 and T-47D) and in the normal mammary epithelial cell line MCF10a. Using competitive RT-PCR, we have shown that PRL induced an increase in BRCA1 mRNA level in MCF-7 and T-47D cell lines at a dose resulting in the maximal enhancement of cell proliferation. The up-regulation was 12-fold in MCF-7 cells and 2-fold in T-47D cells. No increase in BRCA1 mRNA level was observed in the MCF10a cell line. The level of BRCA1 protein was quantified using an affinity chromatography strategy. At the protein level, PRL treatment induced a 4-fold increase of BRCA1 protein expression in MCF-7 and a 6-fold increase in T-47D cells, whereas BRCA1 protein expression was not affected by PRL in MCF10a.
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Affiliation(s)
- D A Favy
- Laboratoire d'Oncologie Moléculaire, INSERM CRI 9502 and EA 2145, Centre Jean Perrin, 58, rue Montalembert, Clermont-Ferrand, Cedex 1, 63011, France
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14
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Rio PG, Maurizis JC, Peffault de Latour M, Bignon YJ, Bernard-Gallon DJ. Quantification of BRCA1 protein in sporadic breast carcinoma with or without loss of heterozygosity of the BRCA1 gene. Int J Cancer 1999; 80:823-6. [PMID: 10074913 DOI: 10.1002/(sici)1097-0215(19990315)80:6<823::aid-ijc5>3.0.co;2-3] [Citation(s) in RCA: 42] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
In sporadic breast cancer, no mutations of the BRCA1 gene have been reported so far, whereas BRCA1 mRNA is markedly decreased in invasive breast cancer. To elucidate the contribution of the BRCA1 gene in sporadic breast cancer, we quantified the BRCA1 protein, using [125I] labeling of whole-cell proteins, lentil-lectin affinity chromatography, immunoprecipitation by anti-BRCA1 antibodies (C-20, D-20, I-20 and K-18), purification of the immune complex by protein A affinity chromatography and chromato-focusing. As loss of 1 allele may lead to a decreased expression of the gene, 10 tumors were previously checked for loss of heterozygosity (LOH) of the BRCA1 gene, using 3 intragenic microsatellite markers. Our results indicated that the BRCA1 gene product was decreased in the 4 tumors with LOH compared with matched normal breast tissues. Reduced amounts of BRCA1 protein were also detected in 3 of 6 tumors without LOH. Our quantitative method allowed us to demonstrate that the BRCA1 protein level was decreased in sporadic invasive breast carcinomas with or without LOH of the BRCA1 gene, implying multiple mechanisms of BRCA1 expression down-regulation in these tumors. Our data suggest that the amount of BRCA1 protein present may play an important role in human sporadic breast carcinoma.
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Affiliation(s)
- P G Rio
- Laboratoire d'Oncologie Moléculaire, INSERM CRI 9502 and EA 2145, Centre Jean Perrin, Clermont-Ferrand, France
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15
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Abstract
Current evidence strongly supports a role for the breast cancer susceptibility genes, BRCA1 and BRCA2, in both normal development and carcinogenesis. Valuable clues regarding the function of these genes have been garnered through studies of their patterns of expression. A central feature of the in vivo pattern of BRCA1 and BRCA2 expression is that each of these putative tumor suppressor genes is expressed at maximal levels in rapidly proliferating cells. This feature is consistent with in vitro observations that BRCA1 and BRCA2 are expressed in a cell cycle-dependent manner. This feature is also well illustrated during mammary gland development wherein the expression of BRCA1 and BRCA2 is induced in rapidly proliferating cellular compartments undergoing differentiation, such as terminal end buds during puberty and developing alveoli during pregnancy. Strikingly, the spatial and temporal patterns of BRCA1 and BRCA2 expression are virtually indistinguishable during embryonic development and in multiple adult tissues despite the fact that these genes are unrelated. These observations have contributed to the emerging hypothesis that these genes function in similar regulatory pathways.
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Affiliation(s)
- L A Chodosh
- Department of Molecular and Cellular Engineering, University of Pennsylvania School of Medicine, Philadelphia 19104-6100, USA.
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