Sub Hypomethylation Of Clinical Research Myeloid Neoplasms RAGE-1 Gene

Objective To investigate the methylation status of renal tumor antigen-1(RAGE-1) gene promoter and explore its clinical relevance in patients with myeloid malignancies including acute myeloid leukemia (AML),chronic myeloid leukemia (CML) and myelodysplastic syndrome (MDS).Methods Real-time quantitative PCR(RQ-PCR) was used to analyze RAGE-1mRNA level in the bone marrow mononuclear cells(BMNCs) from94AML cases,45CML patients,25MDS patients and25controls. Real-time quantitative methylation-specific PCR (RQ-MSP) techniques were used to detect the unmethylation level of RAGE-1gene promoter in the BMNCs from the patients with AML (n=121), CML (n=76), MDS (n=80) and controls (n=25). The bisulfite sequencing was performed to analyze the methylation density of RAGE-1promoter in patients with AML.Results The hypomethylation of RAGE-1promoter was present in the hematologic myeloid malignancies:①RAGE-1hypomethylation was observed in52among121AML cases (42.9%); the frequency of RAGE-1hypomethylation was not associated with the sex, age, hemoglobin level, white blood cell counts and platelet counts of patients (P>0.05). The RAGE-1hypomethylation frequency was not associated with FAB subtypes and AML karyotypic groups (P>0.05). The overall survival was significantly longer in patients with hypomethylated RAGE-1than in those without hypomethylated RAGE-1(χ2=5.586, P=0.018). A positive correlation was observed between the level of RAGE-1unmethylation and the level of RAGE-1expression (r=0.632, P=0.011). High relevance between RQ-MSP and bisulfite sequencing was shown. In addition, the overall methylation density of samples was inversely correlated with the level of RAGE-1expression.②RAGE-1promoter hypomethylation was found in33CML cases (43.4%), the hypomethylation incidence was not associated with the sex, age, hemoglobin concentration, white blood cell countsof patients (P>0.05), but correlated with the platelet counts. The patients with RAGE-1promoter hypermethylation had higher platelet counts than those without RAGE-1promoter hypermethylation (P=0.043). The frequencies of RAGE-1promoter hypomethylation in patients of blast crisis, accelerated phase and chronic phase were53.8%(7/13),50.0%(2/4) and40.7%(24/59), respectively. The difference was not statistically significant (P>0.05). The hypomethylation incidence was not associated with chromosomal abnormalities. A positive correlation was found between the level of RAGE-1unmethylation and the level of RAGE-1transcript (r=0.457, P=0.002).③RAGE-1hypomethylation was found in46(57.5%) MDS cases, the methylation alteration of RAGE-1promoter was not associated with the sex, age, hemoglobin level, white blood cell counts, platelet counts and chromosomal abnormalities of patients (P>0.05). There was no significant difference in hypomethylation incidence among WHO, FAB or IPSS subtypes (P>0.05). The overall survival was no significant difference between hypomethylated patients and methylated cases (χ2=0.017, P=0.986). A positive correlation was observed between the level of RAGE-1unmethylation and the level of RAGE-1transcript (r=0.562, P=0.003).Conclusions①RAGE-1promoter hypomethylation is a common molecular event in cases with myeloid malignancies;②RAGE-1promoter hypomethylation is a molecular marker for favorable prognosis in AML patients.