Methylation and Expression of Retinoblastoma and Transforming Growth Factor-β1 Genes in Epstein-Barr Virus-Associated and -Negative Gastric Carcinomas

Abstract

Background. Retinoblastoma (RB) and transforming growth factor-β1 (TGF-β1) are important tumor-related factors.Methods. A series of 30 EBV-associated gastric carcinoma (EBVaGC) and 38 matched EBV-negative gastric carcinoma (EBVnGC) tissues were examined for the promoter methylation ofRBby methylation-specific PCR (MSP) method. The expression ofRBandTGF-β1in gastric carcinoma tissues was detected by immunohistochemistry.Results. The methylation rate ofRBgene in EBVaGC and EBVnGC was 80.0% (24/30) and 50.0% (19/38), respectively. The difference ofRBmethylation rate between EBVaGC and EBVnGC was significant(χ2=6.490,  P=0.011). There was no significant difference forRBexpression between EBVaGC (43.3%, 13/30) and EBVnGC (63.2%, 24/38), and also forTGF-β1between EBVaGC (56.7%, 17/30) and EBVnGC (63.2%, 24/38).RBmethylation was not reversely correlated withRBexpression in gastric carcinoma tissues(χ2=2.943,  P=0.086,  r=0.208).RBmethylation, loss expression ofRB, andTGF-β1expression were significantly associated with tumor invasion and lymph node metastasis (P<0.05), but was not associated with sex, age, histological subtype (differentiation status) and tumor location.Conclusions. Methylation ofRBis a common event in gastric carcinomas and EBV induces methylation ofRBin EBVaGC, which may contribute to the development of gastric carcinomas. EBV has no significant effect on induction ofTGF-β1expression. Detection ofRBmethylation,RBexpression, andTGF-β1expression may be helpful to judge the status of tumor invasion and lymph node metastasis in gastric carcinomas.