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. 2008;10(1):R12.
doi: 10.1186/bcr1858. Epub 2008 Feb 12.

BRCA1 promoter methylation in peripheral blood DNA of mutation negative familial breast cancer patients with a BRCA1 tumour phenotype

Cameron Snell  1 , Michael Krypuy, Ee Ming Wong; kConFab investigators; Maurice B Loughrey, Alexander Dobrovic
Affiliations

BRCA1 promoter methylation in peripheral blood DNA of mutation negative familial breast cancer patients with a BRCA1 tumour phenotype

Cameron Snell et al. Breast Cancer Res. 2008.

Abstract

Introduction: Individuals with germline mutations in the BRCA1 gene have an elevated risk of developing breast cancer, and often display characteristic clinicopathological features. We hypothesised that inactivation of BRCA1 by promoter methylation could occur as a germline or an early somatic event that predisposes to breast cancer with the phenotype normally associated with BRCA1 germline mutation.

Methods: We examined seven cases from breast-ovarian cancer families with tumours that showed BRCA1-like pathology but did not have detectable BRCA1 or BRCA2 germline mutations present. Methylation levels were tested by several quantitative techniques including MethyLight, methylation-sensitive high resolution melting (MS-HRM) and a newly developed digital MS-HRM assay.

Results: In one patient, methylation of 10% of the BRCA1 alleles was detected in the peripheral blood DNA, consistent with 20% of cells having one methylated allele. Buccal mucosa DNA from this individual displayed approximately 5% BRCA1 methylation. In two other patients, methylation of BRCA1 was detected in the peripheral blood at significantly lower but still readily detectable levels (approximately 1%). Tumour DNAs from these three patients were heavily methylated at BRCA1. The other patients had no detectable BRCA1 methylation in their peripheral blood. One of seven age-matched controls showed extremely low levels of methylation in their peripheral blood (approximately 0.1%).

Conclusion: These results demonstrate that in some cases of breast cancer, low-level promoter methylation of BRCA1 occurs in normal tissues of the body and is associated with the development of BRCA1-like breast cancer.

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Figures

Figure 1
Figure 1
Map of the BRCA1 promoter region studied by the MethyLight and MS-HRM assays. The numbering of the promoter is according to that used by Rice et al. [24]. TSS denotes the transcription start site. The positions of the primers flanking the MethyLight and MS-HRM amplicons are indicated as well as the position of the MethyLight probe.
Figure 2
Figure 2
Methylation analysis of BRCA1 in KCF3. (a) MethyLight results for BRCA1 and control gene HMBS for samples from KCF3. The BRCA1 MethyLight assay indicates the presence of methylated DNA for the peripheral blood leukocyte (PBL), buccal mucosa (BUC) and tumour (TUM) of KCF3. The HMBS control gene indicates the amount of bisulfite modified DNA for each sample of KCF3. (b) Methylation-sensitive high resolution melting (MS-HRM) results for samples from KCF3. The PBL sample (pink curve) and the BUC sample (green curve) show methylation levels close to the 10% methylated control. The TUM sample (orange curve) shows a much higher level of methylation.
Figure 3
Figure 3
Digital methylation-sensitive high resolution melting (MS-HRM) and sequencing for KCF3 peripheral blood DNA. The blue curve indicates the unmethylated control. The black curve indicates the methylated control. The green curves indicate unmethylated amplicons. The red curves indicate methylated amplicons. Sequencing for the unmethylated and methylated controls are shown above the digital MS-HRM results. Sequences of the indicated red amplicons (lettered) are shown to right of the figure where the letter to the right of the chromatograph corresponds to the curve shown.
Figure 4
Figure 4
Methylation analysis of BRCA1 in KCF1 and KCF4. (a) MethyLight results for BRCA1 and the control gene HMBS for samples from KCF1 and KCF4. The BRCA1 MethyLight assay indicates the presence of methylated DNA for the peripheral blood (PBL) and tumour (TUM) for both individuals. (b) The methylation-sensitive high resolution melting (MS-HRM) assay also shows the presence of methylation in the peripheral blood and tumour for both individuals.
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References

    1. Miki Y, Swensen J, Shattuck-Eidens D, Futreal PA, Harshman K, Tavtigian S, Liu Q, Cochran C, Bennett LM, Ding W, Bell R, Rosenthal J, Hussey C, Than T, McClure M, Frye C, Hattier T, Phelps R, Haugen-Strano A, Katcher H, Yakumo K, Gholami Z, Shaffer D, Stone S, Bayer S, Wray C, Bogden R, Dayananth P, Ward J, Tonin P, et al. A strong candidate for the breast and ovarian cancer susceptibility gene BRCA1. Science. 1994;266:66–71. doi: 10.1126/science.7545954. - DOI - PubMed
    1. Eisinger F, Stoppa-Lyonnet D, Longy M, Kerangueven F, Noguchi T, Bailly C, Vincent-Salomon A, Jacquemier J, Birnbaum D, Sobol H. Germ line mutation at BRCA1 affects the histoprognostic grade in hereditary breast cancer. Cancer Res. 1996;56:471–474. - PubMed
    1. Pathology of familial breast cancer: differences between breast cancers in carriers of BRCA1 or BRCA2 mutations and sporadic cases. Breast Cancer Linkage Consortium. Lancet. 1997;349:1505–1510. doi: 10.1016/S0140-6736(96)10109-4. - DOI - PubMed
    1. Armes JE, Egan AJ, Southey MC, Dite GS, McCredie MR, Giles GG, Hopper JL, Venter DJ. The histologic phenotypes of breast carcinoma occurring before age 40 years in women with and without BRCA1 or BRCA2 germline mutations: a population-based study. Cancer. 1998;83:2335–2345. doi: 10.1002/(SICI)1097-0142(19981201)83:11<2335::AID-CNCR13>3.0.CO;2-N. - DOI - PubMed
    1. Johannsson OT, Idvall I, Anderson C, Borg A, Barkardottir RB, Egilsson V, Olsson H. Tumour biological features of BRCA1-induced breast and ovarian cancer. Eur J Cancer. 1997;33:362–371. doi: 10.1016/S0959-8049(97)89007-7. - DOI - PubMed

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