Wojdacz, Tomasz K6; Windeløv, Johanne Agerlin5; Thestrup, Britta Boserup6; Damsgaard, Tine Engberg7; Overgaard, Jens8; Hansen, Lise Lotte6
1 Department of Biomedicine, Health, Aarhus University2 Department of Clinical Medicine - Department of Experimental Clinical Oncology, Department of Clinical Medicine, Health, Aarhus University3 Department of Clinical Medicine - Plastikkirurgisk afdeling Z, Department of Clinical Medicine, Health, Aarhus University4 Department of Biomedicine - Forskning og uddannelse, Øst, Department of Biomedicine, Health, Aarhus University5 Department of Human Genetics, Faculty of Health Sciences, Aarhus University, Aarhus University6 Department of Biomedicine - Forskning og uddannelse, Øst, Department of Biomedicine, Health, Aarhus University7 Department of Clinical Medicine - Plastikkirurgisk afdeling Z, Department of Clinical Medicine, Health, Aarhus University8 Department of Clinical Medicine - Department of Experimental Clinical Oncology, Department of Clinical Medicine, Health, Aarhus University
INTRODUCTION: Despite similar clinical and pathological features, large numbers of breast cancer patients experience different outcomes of the disease. This, together with the fact that the incidence of breast cancer is growing worldwide, emphasizes an urgent need for identification of new biomarkers for early cancer detection and stratification of patients. METHODS: We used ultrahigh-resolution microarrays to compare genomewide methylation patterns of breast carcinomas (n = 20) and nonmalignant breast tissue (n = 5). Biomarker properties of a subset of discovered differentially methylated regions (DMRs) were validated using methylation-sensitive high-resolution melting (MS-HRM) in a case-control study on a panel of breast carcinomas (n = 275) and non-malignant controls (n = 74). RESULTS: On the basis of microarray results, we selected 19 DMRs for large-scale screening of cases and controls. Analysis of the screening results showed that all DMRs tested displayed significant gains of methylation in the cancer tissue compared to the levels in control tissue. Interestingly, we observed two types of locus-specific methylation, with loci undergoing either predominantly full or heterogeneous methylation during carcinogenesis. Almost all tested DMRs (17 of 19) displayed low-level methylation in nonmalignant breast tissue, independently of locus-specific methylation patterns in cases. CONCLUSIONS: Specific loci can undergo either heterogeneous or full methylation during carcinogenesis, and loci hypermethylated in cancer frequently show low-level methylation in nonmalignant tissue.
Breast Cancer Research (online Edition), 2014, Vol 16