Hypermethylation of the RASSF1A gene in gliomas

Abstract

Background Promoter methylation is an important pathway in transcriptional silencing of tumor suppressor genes (TSGs) in brain tumors. The identified 3p21.3 tumor suppressor gene RAS association domain family protein 1A ( RASSF1A) is highly methylated in primary lung, breast and other tumors. We investigated the promoter methylation and gene expression of RASSF1A in gliomas. Methods The methylation status of the promoter region of RASSF1A, p16 INK4A and death-associated protein kinase ( DAPK) genes was analyzed by methylation-specific PCR (MSP) in 41 surgically resected gliomas. RASSF1A expression was also detected by reverse-transcription polymerase chain reaction (RT-PCR) in 28 glioma tissues. Results The frequencies of RASSF1A, p16 INK4A and DAPK promoter methylation were 13/41 (31.7%), 3/41 (7.3%) and 6/41 (14.6%) respectively. However, the methylations of those genes were not correlated with the clinical characteristics of patients (tumor grade, tumor types and sex). Among 28 glioma tissues, 6 showed the loss of the gene (21.4%). Promoter hypermethylation of RASSF1A is associated with loss of gene expression in glioma tissues. ( p=0.022). Conclusions Our results suggested that the RASSF1A gene might play an important role in glioma carcinogenesis. It also gives us an insight for future glioma medical therapy with a demethylating agent.