Loss of heterozygosity at the RB-1 locus and pRB immunostaining in epithelial ovarian tumors: a molecular, immunohistochemical, and clinicopathologic study

Int J Gynecol Pathol. 2001 Oct;20(4):335-40. doi: 10.1097/00004347-200110000-00004.

Abstract

Alterations in the retinoblastoma gene (RB-1) are common in human neoplasia. The frequency of loss of heterozygosity (LOH) at the RB-1 locus on chromosome 13q14 was studied in a series of 51 epithelial ovarian tumors (10 benign, 7 borderline, and 34 malignant). LOH was scored by the absence or reduction of the signal to < 50% of one of the alleles in tumor DNA compared with normal DNA. LOH results were correlated with retinoblastoma protein (pRB) immunostaining. LOH at the RB-1 locus was observed in 9 tumors (17.6%), specifically in 1 of 7 borderline tumors and 8 of 34 ovarian carcinomas (23.5%). Among the malignant tumors, LOH occurred more frequently in carcinomas with serous differentiation (7/23; 30%). A heterogeneous (10% to 70% cells) or diffuse (> 70% cells) pRB immunostaining was less frequent in benign (1/10; 10%) and borderline (2/7; 28%) tumors than in ovarian carcinomas (15/34; 44%), an observation that correlated with the higher proliferative index in carcinomas than in benign and borderline tumors. However, lack or only focal (< 10% cells) pRB immunostaining occurred in the vast majority of tumors with LOH at the RB-1 locus (7/9; 77%), a finding that may suggest a tumor suppressor role for RB-1 in these tumors. The results suggest that RB-1 may play a role in a subset of ovarian carcinomas, particularly those exhibiting serous differentiation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenocarcinoma, Clear Cell / genetics
  • Adenocarcinoma, Clear Cell / pathology
  • Adenocarcinoma, Mucinous / genetics
  • Adenocarcinoma, Mucinous / pathology
  • Carcinoma / chemistry
  • Carcinoma / genetics*
  • Carcinoma / pathology
  • Carcinoma, Endometrioid / genetics
  • Carcinoma, Endometrioid / pathology
  • Chromosomes, Human, Pair 13
  • Cystadenocarcinoma / genetics
  • Cystadenocarcinoma / pathology
  • Female
  • Humans
  • Immunohistochemistry
  • Loss of Heterozygosity*
  • Ovarian Neoplasms / chemistry
  • Ovarian Neoplasms / genetics*
  • Ovarian Neoplasms / pathology
  • Retinoblastoma Protein / analysis
  • Retinoblastoma Protein / genetics*

Substances

  • Retinoblastoma Protein