Frequent promoter hypermethylation of BRCA2, CDH13, MSH6, PAX5, PAX6 and WT1 in ductal carcinoma in situ and invasive breast cancer

• Published in: The Journal of pathology Vol. 225; no. 2; pp. 222 - 231
• Main Authors: Moelans, Cathy B, Verschuur-Maes, Anoek HJ, van Diest, Paul J
• Format: Journal Article
• Language: English
• Published: Chichester, UK John Wiley & Sons, Ltd 01.10.2011; Wiley
• Subjects: Biological and medical sciences; BRCA2 protein; Breast cancer; Breast Neoplasms - genetics; Breast Neoplasms - pathology; Cadherins - genetics; Carcinoma; Carcinoma in Situ - genetics; Carcinoma in Situ - pathology; Carcinoma, Ductal, Breast - genetics; Carcinoma, Ductal, Breast - pathology; Cell cycle; CpG islands; DCIS; Development; DNA methylation; DNA Methylation - genetics; DNA repair; DNA-Binding Proteins - genetics; epigenetics; Eye Proteins - genetics; Female; Genes, BRCA2; Genes, Wilms Tumor; Glutathione transferase; Gynecology. Andrology. Obstetrics; Homeodomain Proteins - genetics; Humans; Invasiveness; Investigative techniques, diagnostic techniques (general aspects); Mammary gland diseases; Medical sciences; methylation; Microdissection; MS-MLPA; MSH6 protein; Paired Box Transcription Factors - genetics; Pathology. Cytology. Biochemistry. Spectrometry. Miscellaneous investigative techniques; Pax5 protein; PAX5 Transcription Factor - genetics; Pax6 protein; PAX6 Transcription Factor; Promoter Regions, Genetic - genetics; Promoters; Repressor Proteins - genetics; Transcription factors; Tumor suppressor genes; Tumors; H Cadherin; Ductal carcinoma; Breast disease; Carcinoma in situ; Transcription promoter; In situ; Breast cancer; Wilms tumor gene; Malignant tumor; Repair gene; Mammary gland diseases; Anatomic pathology; Multiplex ligation dependent probe amplification; BRCA2 gene; DCIS; MS-MLPA; Frequency; Invasive cancer; Methylation; Cancer; Tumor suppressor gene
• ISSN: 0022-3417; 1096-9896
• DOI: 10.1002/path.2930

Epigenetic changes are considered to be a frequent event during tumour development. Hypermethylation of promoter CpG islands represents an alternative mechanism to inactivate tumour suppressor genes, DNA repair genes, cell cycle regulators and transcription factors. In search of epigenetic events related to progression, we used MS–MLPA (ME‐0002‐B1, MRC‐Holland, Amsterdam, The Netherlands) to compare the methylation status of 25 breast cancer‐related genes between laser‐microdissected ductal carcinoma in situ (DCIS) and adjacent invasive ductal cancer (IDC) lesions in 33 breast cancer patients. Using absolute methylation percentages or, alternatively, a 15% cut‐off for methylation, promoter methylation in DCIS and IDC was not significantly different for any of the genes studied. Aberrant methylation in at least 50% of both the DCIS and adjacent IDC lesions was observed for PAX6, BRCA2, PAX5, WT1, CDH13 and MSH6. Methylation of MSH6, however, was also frequent in normal breast tissue. In contrast, CDKN2A, CHFR, PYCARD and one of the two analysed RB1 CpG loci were rarely (<5%) methylated in both lesions. CDKN2A and GSTP1 showed significantly (p < 0.002) higher mean methylation levels in increasing grades (I, II, III) of DCIS (1% versus 4% versus 7% for CDKN2A and 6% versus 26% versus 28% for GSTP1). The mean number of methylated genes per sample increased with increasing grades of DCIS (p = 0.014) and IDC (p = 0.109). In contrast to the observations in DCIS, none of the analysed genes showed significantly higher methylation levels with increasing grades of IDC. In conclusion, there were no differences in promoter methylation between DCIS and IDC in the 25 analysed genes, suggesting that DCIS, at the epigenetic level, is as advanced as IDC. Promoter hypermethylation of PAX6, BRCA2, PAX5, WT1, CDH13 and MSH6 seems to be a frequent early event in breast cancer and methylation levels of GSTP1 (and CDKN2A, although still low) seem to increase with increasing DCIS grade. Copyright © 2011 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.