Tumor Biology

, Volume 35, Issue 5, pp 4047–4056 | Cite as

Methylation of miR-124a-1, miR-124a-2, and miR-124a-3 genes correlates with aggressive and advanced breast cancer disease

  • Riadh Ben Gacem
  • Olfa Ben Abdelkrim
  • Sonia Ziadi
  • Myriam Ben Dhiab
  • Mounir Trimeche
Research Article


Aberrant DNA methylation on CpG islands is one of the most consistent epigenetic changes in human cancers, and the process of methylation is catalyzed by the DNA methyltransferases DNMT1, DNMT3a, and DNMT3b. Recent reports demonstrate that deregulation of miR-124a, one of the frequently methylated microRNAs in human cancers, is related to carcinogenesis. The aim of this study was to evaluate the frequencies of methylation of the three genomic loci encoding the miR-124a in primary breast cancers and to investigate their relationships with the clinicopathological characteristics of the tumors and with the expression levels of DNMT1, DNMT3a, and DNMT3b. The methylation status of the three genomic loci encoding the miR-124a (miR-124a-1, miR-124a-2, and miR-124a-3) was analyzed in fresh-frozen tumor samples using methylation-specific PCR in a large series of invasive breast ductal carcinomas (n = 60). Results were correlated to several clinicopathological characteristics of the tumors and to the expression levels of DNMT1, DNMT3a, and DNMT3b, determined by immunohistochemistry. Promoter hypermethylation of miR-124a-1, miR-124a-2, and miR-124a-3 was detected in 53.3, 70, and 36.7 % of cases, respectively. Methylation of miR-124a-2 correlated to patients with age higher than 45 years (P = 0.008) and to postmenopausal patients (P = 0.03), whereas methylation of miR-124a-3 correlated significantly to tumor size >20 mm (P = 0.03). Interestingly, simultaneous methylation of the three genes encoding miR-124a correlated significantly with the presence of lymph node metastasis (P = 0.01) and high mitotic score (P = 0.03). No significant correlation was found between promoter hypermethylation of miR-124a and expression of hormone receptors or HER2/neu. With regard to DNMT expression, no correlation was found between DNMT1 or DNMT3a expression and promoter methylation of any tested microRNA. However, DNMT3b overexpression correlates significantly with the hypermethylation of miR-124a-3 (P = 0.03). Our data indicates that miR-124a-1, miR-124a-2, and miR-124a-3 genes are frequently methylated in breast cancer and play a role in tumor growth and aggressivity.


microRNA Methylation Breast cancer 



This work was supported by the “Ministère de l'Enseignement Supérieur, de la Recherche Scientifique et Technologie” and the “Ministère de la Santé” of Tunisia.

Conflicts of interest


Supplementary material

13277_2013_1530_MOESM1_ESM.doc (46 kb)
Supplementary Table1 Association between DNMT1, -3a, and -3b overexpressions and miR-124a promoter hypermethylation (DOC 46 kb)


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Copyright information

© International Society of Oncology and BioMarkers (ISOBM) 2013

Authors and Affiliations

  • Riadh Ben Gacem
    • 1
  • Olfa Ben Abdelkrim
    • 1
  • Sonia Ziadi
    • 1
  • Myriam Ben Dhiab
    • 1
  • Mounir Trimeche
    • 1
  1. 1.Department of PathologyFarhat-Hached HospitalSousseTunisia

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