Methylation Status Of RASSF1A Promoter And The Association With Clinicopathologic Characteristics In Retinoblastoma

ObjectiveTo detect the methylation status of RASSF1A promoter in retinoblastoma tissue or in peripheral blood of patients with retinoblastoma. To investigate the association of the methylation status of RASSF1A promoter with clinicopathologic characteristics or the risk of recurrence after enucleation.MethodsIt was an experimental study on the parafin-embeded retinoblastoma tissue sections,and an case-control study on retinoblastoma case and normal healthy people.Methylation status of RASSF1A promoter in 39 RB tissues and in 25 corresponding peripheral blood samples of RB were detected by methylation specific PCR (MSP), The association between methylation status of RASSF1A promoter and clinicopathologic characteristics the differences of methylation rate among different groups were analyzed by Fisher's exact probability test.Results1. The percentage of RASSF1A hypermethylation in RB tissues (66.7%) ) was much higher than in normal retinal tissue.2. The RASSF1A hypermethylation percentage in tumor tissues of the unilateral RB was higher significantly than of the bilateral RB(P<0.01).3. There was no significant statistics difference in RASSF1A methylation rate of peripheral blood between RB patients 32%(8/25) and normal healthy people(0/5).4. Compared with optic nerve un-invaded group(1/14),the rate of RASSF1A promoter methylation in peripheral blood in optic nerve invadedgroup (7/10) was much higher.5.The ratio of RB recurrence after enucleation was 36.4%(8/22).Therewas no significantly statistics difference between RASSF1A methylated group and unmethylated group(P>0.05).Conclusion1. RASSF1A promoter hypermethylation was a common epigenetical event with high frequency in retinoblastoma, specially in unilateral RB.2. RASSF1A promoter hypermethylation in tissues might be helpful in diagnosis of retinoblastoma.3. RASSF1A promoter hypermethylation in peripheral blood of RBpatients might have portential prediction to the risk of recurrence in retinoblastoma.