Loss of heterozygosity at the RB-1 locus and pRB immunostaining in epithelial ovarian tumors: a molecular, immunohistochemical, and clinicopathologic study.
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.
Gras
E
E
Department of Pathology, Hospital Santa Creu i Sant Pau, Autonomous University of Barcelona, Spain.
Pons
C
C
Machin
P
P
Matias-Guiu
X
X
Prat
J
J
D018262:Adenocarcinoma, Clear Cell / Q000235:genetics / Q000473:pathology; D002288:Adenocarcinoma, Mucinous / Q000235:genetics / Q000473:pathology; D002277:Carcinoma / Q000737:chemistry / Q000235:genetics* / Q000473:pathology; D018269:Carcinoma, Endometrioid / Q000235:genetics / Q000473:pathology; D002882:Chromosomes, Human, Pair 13; D003536:Cystadenocarcinoma / Q000235:genetics / Q000473:pathology; D005260:Female; D006801:Humans; D007150:Immunohistochemistry; D019656:Loss of Heterozygosity; D010051:Ovarian Neoplasms / Q000737:chemistry / Q000235:genetics* / Q000473:pathology; D016160:Retinoblastoma Protein / Q000032:analysis / Q000235:genetics*
D016160:Retinoblastoma Protein