微型核糖核酸基因let-7a-3在急性骨髓性白血病病人之甲基化情形

Abstract

Let-7 family miRNAs repress several genes involved in cell cycle, including RAS and HMGA2 . By this way, they play specific roles in cell proliferation, differentiation and the other biological processes. Let-7a-3 belongs to the archetypal let-7 miRNA gene family and was found to be regulated by epigenetic regulation. Recent study showed that let-7a-3 was methylated in epithelial ovarian cancer and methylation status was associated with survival of patients. In this study, we speculate the methylation status of let-7a-3 and its significance in acute myeloid leukemia. Combined bisulfite restriction analysis（COBRA）were used to evaluate the let-7a-3 methylation status in 90 AML patients. We found that let-7a-3 was methylated in 73 patients（81.1％）, partial methylated in 11 patients（12.2％）and unmethylated in 6 patients（6.7％）. Of them, 16 patients were simultaneously analyzed for methylation status of 33 CpG sites in let-7a-3 promoter region by using bisulfite sequencing PCR method （BSSP）. BSSP demonstrated similar results to the COBRA method, showing the methylation levels ranged from 56％ to 86％ in patients with let-7a-3 methylated, 45％ to 58％ in patients with let-7a-3 partial methylated and 12％ to 15％ in patients with let-7a-3 unmethylated. Chi-square test was performed to assess the association of let-7a-3 methylation status with patients’ age, gender and FAB subtype . We found that let-7a-3 methylation status was negatively correlated with karyotype and CEBPA methylation significantly（0.006 and 0.002, respectively）. Kaplan-Meier survival analysis showed that let-7a-3 methylation in AML patients with intermediate karyotype or CEBPA unmethylation had better prognosis.