Promoter hypermethylation inactivates CDKN2A, CDKN2B and RASSF1A genes in sporadic parathyroid adenomas

Sci Rep. 2017 Jun 9;7(1):3123. doi: 10.1038/s41598-017-03143-8.


Cyclin D1, a G1-S phase regulator, is upregulated in parathyroid adenomas. Since cyclin-dependent kinase (CDK) inhibitors, CDKN2A and CDKN2B, and RASSF1A (Ras-association domain family 1, isoform A) are involved in G1-S phase arrest and act as potential tumor suppressor genes, we aimed to study potential methylation-mediated inactivation of these genes in parathyroid adenomas. Gene expressions of cyclin D1 (CCND1) and regulatory molecules (CDKN2A, CDKN2B and RASSF1A) was analysed in parathyroid adenoma tissues (n = 30). DNA promoter methylation of cyclin D1 regulators were assessed and correlated with clinicopathological features of the patients. Gene expression analysis showed a relative fold reductions of 0.35 for CDKN2A (p = 0.01), 0.45 for CDKN2B (P = 0.02), and 0.39 for RASSF1A (p < 0.01) in adenomatous compared to normal parathyroid tissue. There was an inverse relationship between the expressions of CDKN2A and CDKN2B with CCND1. In addition, the promoter regions of CDKN2A, CDKN2B, and of RASSF1A were significantly hyper-methylated in 50% (n = 15), 47% (n = 14), and 90% (n = 27) of adenomas respectively. In contrast, no such aberrant methylation of these genes was observed in normal parathyroid tissue. So, promoter hypermethylation is associated with down-regulation of CCND1 regulatory genes in sporadic parathyroid adenomas. This dysregulated cell cycle mechanism may contribute to parathyroid tumorigenesis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenoma / genetics*
  • Adolescent
  • Adult
  • Cyclin D1 / genetics
  • Cyclin-Dependent Kinase Inhibitor p15 / genetics*
  • Cyclin-Dependent Kinase Inhibitor p16
  • Cyclin-Dependent Kinase Inhibitor p18 / genetics*
  • DNA Methylation*
  • Down-Regulation*
  • Epigenesis, Genetic
  • Female
  • Gene Expression Profiling
  • Gene Expression Regulation, Neoplastic
  • Humans
  • Male
  • Middle Aged
  • Parathyroid Neoplasms / genetics*
  • Promoter Regions, Genetic
  • Sequence Analysis, DNA
  • Tumor Suppressor Proteins / genetics*
  • Young Adult


  • CCND1 protein, human
  • CDKN2A protein, human
  • CDKN2B protein, human
  • Cyclin-Dependent Kinase Inhibitor p15
  • Cyclin-Dependent Kinase Inhibitor p16
  • Cyclin-Dependent Kinase Inhibitor p18
  • RASSF1 protein, human
  • Tumor Suppressor Proteins
  • Cyclin D1