The Signifcance Of Unmethylation Of PRAME Gene Promoter In Hematologic Myeloid Malignancies

Objective To investigate the methylation status of preferentially expressed antigen of melanoma(PRAME) gene promoter and its clinical correlation in patients with hematologic malignancies including myelody splastic syndrome(MDS),acute myeloid leukemia(AML) and chronic myeloid leukemia(CML).Methods The real-time quantitative methylation-specific PCR (RQ-MSP) technique with EvaGreen dye was established and used to detect the unmethylation level of PRAME promoter in the bone marrow mononuclear cells from the patients with MDS(n=57),AML(n=107) CML(n=49) and controls(n=25).Real-tithe quantitative PCR(RQ-PCR) technique with EvaGreen dye was established to measure the expreesion level of PRAME promoter in 56 cases with AML,30 cases with CML and 20 cases with nonmalignant hematological diseases.Reslttlts The unmethylation level of PRAME promoter in 25 controls was(0～100%,median 25.29%).The transcript of PRAME in 20 controls was(0～0.01%,median 0.18%).The unmethylation level of PRAME promoter was found in MDS,AML and CML.①In 57 casas with MDS, PRAME promoter unpomethylation level was(0～1869.59%,median 17.17%).Correlation was not found between PRAME promoter hypomethylation and sex,age,hematologic parameters,FAB classifycation of MDS ppatients(P＞0.05).According to FAB classification,PRAME promoter unpomethylation level increased during disease progresssion(refractory anemia with excess blasts in transformation,RAEB-t＞refractory anemia with excess blasts,RAEB＞refractory anemia,RA/refractory anemia ring siderobla,RAS).The significant difference was observed in the promoter hypomethylation among the patients with RAEB-t,RAEB and RA/RAS(P＜0.05).PRAME promoter hypomethylation was correlated with WHO classification(r=0.265;P=0.048).In WHO classification,PRAME promoter unmethylation level alterlated following in the order(RAEB-1/ RAEB-2/AML＞RA/fractory cytopenia with mμltilineage dyspla sia, RCMD＞Sq-syndrome)(P=0.02).PRAME promoter unmethylation was correlated with IPSS grouping(r=0.347;P=0.01).The unmethylation level in Int-2/High was significantly higher than Low/Int-1(P=0.01).②In 107 AML patients,PRAME promoter unmethylation level(0～5295.76%,median 83.25%) was more than in controls(P＜0.05).No correlation was between PRAME promoter hypomethylation and the sex, ag,WBC counts,platelet counts and FAB classfication of AML patients (P＞0.05).In FAB classfication,the level of unmethylation of PRAME promoter was as follows the order(M2＞M3＞M5＞M1＞M4＞M6) and significant difference was observed among them.In prognosis group of chromosomes with AML patients,the amount unmethylation of PRAME in low-risk group was significantly higher than in the risk group and high-risk group(P＜0.05).The unmethylation level in AML-M2 patients with t(8;21) transcription-positiv were significantly higher than those without t(8;21) transcription(P＜0.05).In 56 AML patients,PRAME expression level was 0～21618.09%,median was 9.79%.Significant different was between the AML patients and 20 controls(P＜0.05).No correlation was between the expression of PRAME and the sex,ag,WBC counts,platelet counts and FAB classfication(P＞0.05).In FAB classfication,the level of expression was as follows the order (M2＞M3＞M4＞M1＞M5) and significant difference was observed among them(P＜0.05).In prognosis group of chromosomes with AML patients, the expression level of PRAME in low-risk group was significantly higher than in the risk group and high-risk group(P＜0.05).PRAME expression level in AML-M2 patients with t(8;21) transcription-positiv were significantly higher than those without t(8;21) transcription(P＜0.05). Correlation was observed between the unmethylation level of PRAME promoter and PRAME expression(r=0.618,P＜0.001).③In 49 CML patients,PRAME promoter unmethylation level(0～28039.05%,median 25.17%) was more than in controls(P＜0.05).Correlation was not found between PRAME promoter hypomethylation and the age,sex, hemoglobin concentration,platelet counts of CML patients(P＞0.05),but found between PRAME promoter hypomethylation and the expression of bcr/abl(r=0.697,P＜0.037).The level of PRAME promoter unmethylation in CML patients at AP and BC were higher than at CP.In 30 CML patients the expression level of PRAME(0.00%～772.25%,median 8.28%) was more than in controls(P＜0.05).Correlation was not found between PRAME expression and the age,sex,hemoglobin concentration, platelet counts of CML patients(P＞0.05),but found between the expression of PRAME and bcr/abl(r=0.617,P=0.003).The expression level in CML patients at AP and BC were higher than at CP.Correlation was also found between the PRAME promoter unmethylation and expression(r=0.612,P=0.009).Conclusions PRAME promoter hypomethylation might be involved in the development of myeloid malignancies including MDS,AML and CML.