氢醌对人骨髓单个核细胞TOPO Ⅱα表达的影响及其可能机制

目的：观察苯代谢物氢醌（hydroquinone,HQ）对人骨髓单个核细胞拓扑异构酶Ⅱα（TOPOⅡα）表达的影响,探讨TOPOⅡα在HQ所致造血毒性中的作用及其调控机制。方法：50μmol/L HQ培养10h的正常人骨髓单个核细胞设为实验组,等体积灭菌蒸馏水培养10h为对照组。Western blot测定TOPOⅡα含量的变化,RT-PCR测定TOPOⅡαmRNA表达水平的改变,ChIP技术观察HQ对骨髓单个核细胞TOPOⅡα启动子组蛋白乙酰化、甲基化水平的影响。结果：①与对照组相比,人骨髓单个核细胞50μmol/L HQ处理10h后,TOPOⅡα含量、TOPOⅡαmRNA水平明显下降,差异有显著性（P〈0.01）;②TOPOⅡα含量降低伴随着TOPOⅡα启动子组蛋白H4乙酰化、组蛋白H3K4甲基化水平的明显降低（P〈0.01）、组蛋白H3K9甲基化水平升高（P〈0.05）,不伴有组蛋白H3乙酰化水平的改变（P〉0.05）。结论：HQ能抑制造血细胞TOPOⅡα的表达;组蛋白化学修饰可能在苯代谢物所致的造血毒性中发挥一定的作用。

Effect of hydroquinone on expression of topoisomerase enzyme Ⅱαin human bone marrow mononuclear cells and the possible mechanism

Objective： To observe the effects of hydroquinone （HQ） on the expression of topoisomerase Ⅱα （TOPO Ⅱα） in human bone marrow mononuclear cells,and to explore the possible regulatory mechanism of TOPO Ⅱα involving in the toxicity of HQ to hematopoietic cells.Methods： Human bone marrow mononuclear cells was exposed to 50 μmol/L HQ for 10 h （used the cells which were exposed to sterile distilled water for 10 h as control）.The expression levels of TOPO Ⅱα mRNA and protein were detected with RT-PCR technique and Western blot method,respectively.The Chromatin Immunoprecipitation （ChIP） assay was carried out to study the possible mechanism of TOPO Ⅱα expression changes.Results： The protein and mRNA expression of TOPO Ⅱα after treated with HQ for 10 h were significantly lower than that in the control （P 0.01）.The decreased content of TOPO Ⅱα was associated with descended level of histone H4 acetylation （P 0.01）,H3K4 methylation （P 0.01） and heightened level of H3K9 methylation of TOPO Ⅱα promoter （P 0.05） than that in the control with the significant difference,but without accompanied with descented level of histone H3 acetylation （P0.05）.Conclusion： HQ can repress the expression of TOPOⅡα in human bone marrow mononuclearcells.The changes of histone chemical modification play definite important role in the benezen’s hematopoietic toxicity.