AML1-ETO融合蛋白对p14^(ARF)基因转录调控的影响

Effect of AML1-ETO Fusion Protein on Transcriptional Regulation of p14^(ARF)

目的:探讨异常转录因子AML1-ETO融合蛋白对p14^(ARF)的转录调控机制。方法:应用荧光实时定量PCR(qRT-PCR)检测转染细胞和对照组细胞以及AML-M2患者白血病细胞p14^(ARF)mRNA的表达;用甲基化特异性聚合酶链反应(MSP)对其p14^(ARF)启动子的甲基化状态进行分析;染色质免疫沉淀技术(Ch IP)研究转染细胞中AML1-ETO与p14^(ARF)启动子之间直接的相互作用情况;应用qRT-PCR检测5-氮杂胞苷(5-Aza)处理后细胞内p14^(ARF) mRNA表达水平。结果:转染了AML1-ETO的U937细胞系和具有AML1-ETO融合基因的AM L-M2患者中,p14^(ARF)的mRNA表达水平下调;p14^(ARF)启动子在对照组细胞株和无AML1-ETO融合基因的AML-M2患者中处于非甲基化状态,在转染细胞株和具有AML1-ETO融合基因的AML-M2患者中处于高甲基化状态;转染细胞沉淀富集的DNA中含有p14^(ARF)的启动子序列;5-Aza能上调p14^(ARF)mRNA的表达。结论:p14^(ARF)是AML1-ETO融合蛋白可能的靶基因,p14^(ARF)启动子高甲基化所致的基因沉默可能是M2b型白血病发生发展的一个重要因素。

Objective： To investigate the effect of transcriptional regulation of aberrant transcription factor AML1-ETO on p14ARF . Methods： P14 ARF expression both in AML1-ETO-expressing cells or U937 nonexpressing cells and in leukemia cells of AML patients with or without t（ 8; 21） was assessed by quantitative PCR. Methylation-specific polymerase chain reaction（ MSP） was used to analyze the methylation status of p14ARF promoter. The chromatin immunoprecipitation（ ChIP）-based PCR was used to investigate the direct interaction between the AML1-ETO and p14ARF promoter in AML1-ETO positive leukemia cell line. And the p14ARF mRNA expression level was detected by qRTPCR after treatment with 5-Aza. Results： AML1-ETO-expressing cell subclone displayed low level of p14ARF mRNA in comparison with the non-transfected U937. In primary bone marrow cells of acute myeloid leukemia containing AML1-ETO,level of p14ARF mRNA was markedly lower when compared with other acute myeloid leukemias lacking this translocation. P14 ARF gene promoter was non-methylated in control group and primary leukemia cells of AML patients without t（ 8; 21） and was hyper-methylated in U937-A/E1-4 and primary leukemia cells of AML patients with t（ 8;21）. The enriched regions in transfected cells were located within p14ARF promoter. 5-Aza could increase the expression of p14ARF . Conclusion： P14 ARF is a possible target gene of AML1-ETO. The p14ARF silencing induced by hypermethlylation may be an important factor for occurrence and development of the M2 b subtype of acute myeloid leukemia.