Hypermethylation of CDKN2A exon 2 in tumor, tumor-adjacent and tumor-distant tissues from breast cancer patients

BMC Cancer

Research Article

Melanie Spitzwieser¹  Elisabeth Entfellner¹  Bettina Werner¹  Margit Cichna-Markl¹  Georg Pfeiler²  Stefan Hacker³  Walter Pulverer⁴ 

[1] Department of Analytical Chemistry, University of Vienna, Währinger Str. 38, 1090, Vienna, Austria;Department of Obstetrics and Gynecology, Division of Gynecology and Gynecological Oncology, Medical University of Vienna, Währinger Gürtel 18-20, 1090, Vienna, Austria;Department of Plastic and Reconstructive Surgery, Medical University of Vienna, Währinger Gürtel 18-20, 1090, Vienna, Austria;Molecular Diagnostics, Austrian Institute of Technology, Muthgasse 11, 1190, Vienna, Austria;

关键词: DNA methylation;    CDKN2A;    Exon 2;    Tumor suppressor genes;    Breast cancer;    Field cancerization;    Tumor-adjacent tissue;    Tumor-distant tissue;    Methylation-sensitive high resolution melting;    Pyrosequencing;   

DOI  :  10.1186/s12885-017-3244-2

 received in 2016-10-26, accepted in 2017-03-29,  发布年份 2017

来源: Springer

【 摘 要 】

BackgroundBreast carcinogenesis is a multistep process involving genetic and epigenetic changes. Tumor tissues are frequently characterized by gene-specific hypermethylation and global DNA hypomethylation. Aberrant DNA methylation levels have, however, not only been found in tumors, but also in tumor-surrounding tissue appearing histologically normal. This phenomenon is called field cancerization. Knowledge of the existence of a cancer field and its spread are of clinical relevance. If the tissue showing pre-neoplastic lesions is not removed by surgery, it may develop into invasive carcinoma.MethodsWe investigated the prevalence of gene-specific and global DNA methylation changes in tumor-adjacent and tumor-distant tissues in comparison to tumor tissues from the same breast cancer patients (n = 18) and normal breast tissues from healthy women (n = 4). Methylation-sensitive high resolution melting (MS-HRM) analysis was applied to determine methylation levels in the promoters of APC, BRCA1, CDKN2A (p16), ESR1, HER2/neu and PTEN, in CDKN2A exon 2 and in LINE-1, as indicator for the global DNA methylation extent. The methylation status of the ESR2 promoter was determined by pyrosequencing.ResultsTumor-adjacent and tumor-distant tissues frequently showed pre-neoplastic gene-specific and global DNA methylation changes. The APC promoter (p = 0.003) and exon 2 of CDKN2A (p < 0.001) were significantly higher methylated in tumors than in normal breast tissues from healthy women. For both regions, significant differences were also found between tumor and tumor-adjacent tissues (p = 0.001 and p < 0.001, respectively) and tumor and tumor-distant tissues (p = 0.001 and p < 0.001, respectively) from breast cancer patients. In addition, tumor-adjacent (p = 0.002) and tumor-distant tissues (p = 0.005) showed significantly higher methylation levels of CDKN2A exon 2 than normal breast tissues serving as control. Significant correlations were found between the proliferative activity and the methylation status of CDKN2A exon 2 in tumor (r = −0.485, p = 0.041) and tumor-distant tissues (r = −0.498, p = 0.036).ConclusionsFrom our results we can conclude that methylation changes in CDKN2A exon 2 are associated with breast carcinogenesis. Further investigations are, however, necessary to confirm that hypermethylation of CDKN2A exon 2 is associated with tumor proliferative activity.

【 授权许可】

CC BY   
© The Author(s). 2017