Epigenetic alteration of p16 and retinoic acid receptor beta genes in the development of epithelial ovarian carcinoma

Tumour Biol. 2014 Sep;35(9):9069-78. doi: 10.1007/s13277-014-2136-1. Epub 2014 Jun 10.

Abstract

Silencing of tumor suppressor and tumor-related genes by promoter hypermethylation is one of the major events in ovarian carcinogenesis. In this study, we analyzed aberrant promoter methylation of p16 and RAR-β genes in 134 epithelial ovarian carcinomas (EOCs), 23 low malignant potential (LMP) tumors, 26 benign cystadenomas, and 15 normal ovarian tissues. Methylation was investigated by methylation-specific PCR (MSP), and the results were confirmed by bisulfite DNA sequencing. Relative gene expression of p16 and RAR-β was done using quantitative reverse transcriptase PCR (qRT-PCR) on 51 EOC cases, 9 LMP tumors, and 7 benign cystadenomas with 5 normal ovarian tissues. Aberrant methylation for p16 and RAR-β was present in 43 % (58/134) and 31 % (41/134) in carcinoma cases, 22 % (05/23) and 52 % (12/23) in LMP tumors, and 42 % (11/26) and 69 % (18/26) in benign cystadenomas. No methylation was observed in any of the normal ovarian tissues. The mRNA expression level of p16 and RAR-β was significantly downregulated in EOC and LMP tumors than the corresponding normal tissues whereas the expression level was normal in benign cystadenomas for p16 and slightly reduced for RAR-β. A significant correlation of p16 promoter methylation was observed with reduced gene expression in EOC. For RAR-β, no significant correlation was observed between promoter methylation and gene expression. Our results suggest that epigenetic alterations of p16 and RAR-β have an important role in ovarian carcinogenesis and that mechanism along with methylation plays a significant role in downregulation of RAR-β gene in ovarian cancer.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Base Sequence
  • Cyclin-Dependent Kinase Inhibitor p16 / genetics*
  • DNA Methylation
  • Down-Regulation
  • Epigenesis, Genetic*
  • Female
  • Gene Expression Regulation, Neoplastic
  • Humans
  • Middle Aged
  • Molecular Sequence Data
  • Neoplasms, Glandular and Epithelial / genetics*
  • Neoplasms, Glandular and Epithelial / pathology
  • Ovarian Neoplasms / genetics*
  • Ovarian Neoplasms / pathology
  • Promoter Regions, Genetic / genetics
  • Proportional Hazards Models
  • Receptors, Retinoic Acid / genetics*
  • Reverse Transcriptase Polymerase Chain Reaction / statistics & numerical data
  • Survival Analysis
  • Young Adult

Substances

  • Cyclin-Dependent Kinase Inhibitor p16
  • Receptors, Retinoic Acid
  • retinoic acid receptor beta