DNA甲基化通过锌指蛋白185调控慢性粒细胞白血病细胞的增殖

锌指蛋白185(ZNF185)属于LIM结构域蛋白,参与细胞的增殖和分化,在多种肿瘤细胞中具有抑癌基因的功能.ZNF185在正常人血液系统细胞中高表达,但目前对白血病细胞的作用未见研究.采用Western blot检测人外周血中性粒细胞、急性粒细胞白血病细胞系HL-60和慢性粒细胞白血病细胞系K562细胞中ZNF185的表达,发现ZNF185在HL-60和K562细胞中的表达水平显著低于外周血中性粒细胞.为了阐明ZNF185对慢性粒细胞白血病细胞增殖的影响,从人外周血中性粒细胞克隆ZNF185编码序列,转染K562细胞,MTT检测细胞增殖,发现过表达ZNF185显著抑制K562细胞的增殖.甲基化特异PCR分析表明:ZNF185启动子在HL-60和K562细胞中高甲基化,用5-氮杂-2′-脱氧胞苷处理K562细胞,促进ZNF185的表达,显著抑制细胞增殖.研究结果表明,ZNF185启动子高甲基化导致其在K562细胞中的表达降低和细胞增殖抑制作用减弱.可能是慢性粒细胞白血病发生或发展的原因之一.

DNA Methylation Regulates Chronic Myeloid Leukemia Cell Proliferation Through ZNF185

Many studies have demonstrated that ZNF185, a LIM domain protein, acts as a tumor suppressor in several types of tumor cell. However, the role of ZNF185 in leukemia cells remains unclear, though it is highly expressed in the cells of human blood system. In the present study, we found dramatically decreased ZNF185 expression in the acute and chronic myeloid leukemia cell line HL-60 and K562 compared with that in normal neutrophils. To explore the role of ZNF185 in the proliferation of myeloid leukemia cells, complete coding sequence of ZNF185 was cloned and transfected into K562 cells, MTT assay showed that over expression of ZNF185 in K562 cells significantly inhibited its proliferation. To explore the molecular mechanism that regulates ZNF185 expression in myeloid leukemia cells, methylation specific PCR (MSP) was performed to determine the methylation status of ZNF185 promoter in the normal PBL neutrophils, HL-60 and K562 cells. Higher methylation of ZNF185 promoter was detected in HL-60 and K562 cells than that in normal PBL neutrophils. Furthermore, treatment of K562 cells with 5-aza-CdR, a DNA demethylation agent, resulted in demethylation of ZNF185 promoter, increased ZNF185 expression and inhibited K562 cell proliferation. Our results indicate that ZNF185 promoter methylation which reduces ZNF185 expression in K562 cells and its ability to inhibit cell proliferation may be one of the molecular mechanisms that are related to the occurrence or development of chromic myeloid leukemia.