Study On The Analysis And Clinical Significance Of RASSF2A Gene Methylation In Diffuse Large B Cell Lymphoma

Objective: Lymphoma is one of hematologic malignancies discovered for a long time.In rencent years,its incidence is rising.Although the treatment of lymphoma continues to improve,the survival of more than half of who suffer from lymphoma can be prolonged,but there are still part of the patient died of the progression of lymphoma.So calls for concern about lymphoma etiology,early diagnosis and targeted therapy are necessary.In recent years,more and more studies showed that epigenetic plays a more and more important role in the formation and development of various tumors,and the DNA methylation is one of the most widely studied epigenetic mechanisms.RASSF2 is one of Ras association domain family,which is a tumor suppressor gene.RASSF2 including RASSF2A,RASSF2B and RASSF2C three transcripts.And RASSF2A has a role in promoting cell apoptosis and inhibiting growth,At the same time it can also inhibit the expression of inflammatory cytokines to inhibit tumor invasion.Researches showed that hypermethylation of RASSF2A promoter in colon cancer,colon cancer cell lines and colon adenoma is very common,at the same time in stomach cancer,endometrial cancer,nasopharyngeal cancer,lung cancer can also detect RASSF2A promoter methylation.the promoter high hypermethylation is an important mechanism which leads to RASSF2A inactivation.For now,there is no report on RASSF2A in lymphoma.This study applied reverse transcription-polymerase chain reaction(Reverse Transcriptase-PCR,RT-PCR)and methylation-specific polymerase chain reaction(Methylation-Specific PCR,MSP)method,by comparison with normal human peripheral blood,discuss the RASSF2A methylation status and mRNA expression between diffuse large B-cell lymphoma patients peripheral blood,and study their relationship with clinical data,and then provide a theoretical basis for diffuse large B-cell lymphoma pathogenesis,clinical diagnosis and treatment.Methods:1 Detect RASSF2A gene methylation status in the peripheral blood between the diffuse large B-cell lymphoma patients and normal human by the MSP,and then analyze the relationship between gene methylation and the clinical data.2 Detect the relative expression of the mRNA of RASSF2A in the peripheral blood between the diffuse large B-cell lymphoma patients and normal human by RT-PCR,and then analyze the relationship between the relative expression of the mRNA of RASSF2A and the clinical data.3 Using the SPSS19.0 software to analyze the statistical data.Results:1 The methylation frequency of RASSF2A gene was 42.5%(17/40)in diffuse large B-cell lymphoma patients' peripheral blood,and 10.0%(4/40)in the normal human peripheral blood,respectively.The difference was statistically significant(P<0.05).Methylation frequency of RASSF2A gene was associated with LDH,extranodal involvment or not and Ki-67(P<0.05).Methylation status of RASSF2A gene was not associated with age,gender,bone marrow and A/B symptom,GCB/Non-GCB,,IPI,clinical stage and ?2 microglobulin(P>0.05).2 The mRNA expression of RASSF2A gene in diffuse large B cell lymphoma patients peripheral blood(0.49±0.13)was significantly lower than that in normal human peripheral blood(0.56±0.17)(P<0.05).The expression of RASSF2A gene was correlated with LDH,extranodal involvment or not,IPI and Ki-67(P<0.05).However,it was not associated with age,gender,bone marrow or not,A/B symptom,GCB/Non-GCB,clinical stage,?2 microglobulin(P>0.05).3 The mRNA expression of RASSF2A gene in diffuse large B cell lymphoma with promoter methylation of the gene(0.41±0.12)was significantly lower than that in diffuse large B cell lymphoma without methylation of the gene(0.55±0.11)(P<0.05).Conclusion:1 The promoter methylation frequency of RASSF2A in diffuse large B cell lymphoma peripheral blood was significantly higher than that in normal human,which suggests that promoter methylation of RASSF2A gene may be associated with the occurrence of diffuse large B cell lymphoma.2 The expression of RASSF2A in diffuse large B cell lymphoma peripheral blood was lower than that in normal human,which suggests that RASSF2A gene may act as a tumor suppressor gene in diffuse large B cell lymphoma.3 The relatively low expression and the hypermethylation of RASSF2A gene were detected in diffuse large B cell lymphoma peripheral blood,which suggests that aberrant promoter hypermethylation of RASSF2A gene may be associated with its low expression.4 The methylation status of RASSF2A gene in diffuse large B cell lymphoma was correlated with LDH and Ki-67 and extranodal involvment or not,which suggests that promoter methylation of RASSF2A may be associated with tumor invasiveness,tumor malignant process and tumor prognosis.