The Significance Of Methylation Detection Of DAPK And FHIT Gene Promoter In Hematologic Malignancies

ObjectiveTo investigate the methylation status of death-associated protein kinase(DAPK),fragile histidine triad(FHIT)gene promoter and clinical relationship in patients with hematologic malignancies including myelodysplastic syndrome(MDS),acute myelogenous leukemia(AML) and chronic myeloid leukemia(CML).MethodsDAPK promoter methylation was detected by the methylation specific PCR(MSP)in bone marrow samples from patients with MDS, AML and CML.FHIT promoter methylation was detected by the MSP in bone marrow samples from patients with MDS.ResultsDAPK promoter hypermethylation was detectable in 37(62.7%) MDS cases.Correlation was not found between DAPK gene hypermethylation and age,hematologic parameters,chromosomal abnormalities of MDS patients,but found between DAPK gene hypermethylation and sex,bone marrow blast percents of MDS cases. Although the significant difference was not observed in the frequencies of DAPK gene hypermethylation among patients with refractory anemia (RA)(2/5,40.0%),refractory cytopenia with multilineage dysplasia (RCMD)and refractory cytopenia with multilineage dysplasia with ringed blasts(RCMD-RS)(12/22,54.5%),refractory anemia with excess blasts-1(RAEB-1)(8/10,80.0%),refractory anemia with excess blasts-2 (RAEB-2)(9/11,81.8%),refractory anemia with excess blasts in transformation/acute myeloid leukemia(RAEBt/AML)(6/8,75.0%)and 5q- syndrome(0/3,0%)(χ~2 =8.417,P=0.077),it was observed among patients with 5q- syndrome,with normal blasts(RA/RCMD)and with excessive blasts(RAEB-1/RAEB-2/AML)(χ~2=9.824,P=0.007). Furthermore,DAPK gene hypermethylation was more frequent in intermediate/high IPSS groups(Int-1/Int-2/High)than in low IPSS group (Low)(P=0.010).DAPK promoter hypermethylation was detectable in 82(73.2%)AML cases.Correlation was not found between DAPK gene hypermethylation and sex,age,hematologic parameters,chromosomal abnormalities of AML patients(P＞0.05).The frequencies of DAPK gene hypermethylation were as follows:66.7%(14/21,M1),72.5%(29/40, M2),69.2%(9/13,M3),90.0%(18/20,M4),66.7%(8/12,M5)and 66.7%(4/6,M6).The significant difference was not observed in the frequencies of DAPK gene hypermethylation among patients with different subtypes(χ~2=4.417,P=0.491).DAPK promoter hypermethylation was detectable in 25(51.0%)CML cases.Correlation was not found between DAPK gene hypermethylation and age,hematologic parameters,chromosomal abnormalities of CML patients,but found between DAPK gene hypermethylation and sex of CML cases(R=0.374,P=0.008).Correlation was found between the frequencies of DAPK gene hypermethylation and different CML stages (R=0.354,P=0.013).The significant difference was observed in the frequencies of DAPK gene hypermethylation among patients with different CML stages(χ~2=8.659,P=0.013).DAPK gene hypermethylation was more frequent in patients at Accelerated Phase(AP)and at Blast Crisis(BC)than in those at Chronic Phase(CP)(χ~2=7.776,P=0.005).FHIT promoter hypermethylation was detectable in 26(48.1%) MDS cases.Correlation was not found between FHIT gene hypermethylation and sex,hematologic parameters,chromosomal abnormalities of MDS patients,but found between FHIT gene hypermethylation and age of MDS patients.Although the significant difference was not observed in the frequencies of FHIT gene hypermethylation among patients with refractory anemia/refractory anemia with ringed sideroblasts(RA/RARS)(1/6,16.7%),RCMD and RCMD-RS(6/19,31.6%),RAEB-1(7/11,63.6%),RAEB-2(4/7,57.1%) and RAEBt/AML(8/11,72.7%)(χ~2 =8.417,P=0.077),it was observed among patients in early stage(RA/RARS and RCMD)(7/25,28.0%), advanced stage(RAEB-1 and RAEB-2)(11/18,61.1%)and RAEBt/AML (8/11,72.7%)(χ~2=7.938,P=0.019).Furthermore,there was a positive correlation between the frequency of FHIT gene hypermethylation and different IPSS groups(χ~2=10.110,P=0.018).ConclusionsDAPK gene hypermethylation might be one of molecular events involved in the development and progression of myeloid malignancies. FHIT gene hypermethylation might be one of molecular events involved in the disease progression of MDS,and it might be an adverse prognostic factor in MDS.