全反式维甲酸诱导K562细胞铁代谢变化的研究

目的 探讨全反式维甲酸(ATRA)对K562白血病细胞中铁代谢相关基因表达产物(H-Fn、TfR及IRP2)的影响及其相互关系.方法 应用联苯胺、瑞氏、非特异性酯酶、硝基四氮唑蓝还原试验4种染色方法 ,观察ATRA对K562细胞的诱导分化特点;应用流式细胞术检测经ATRA处理后,K562细胞表面抗原CD71及CDl3表达水平的变化;应用RNA/蛋白带移动分析方法 (RNA/protein band-shift assay)检测铁调节蛋白(IRP)的结合活性;采用放射免疫分析法测定K562细胞内铁蛋白含量的变化;采用RT-PCR方法 对ATRA处理的K562细胞H-Fn、TfR及IRP2 mRNA水平的表达进行检测,同时对RT-PCR产物克隆测序.结果 K562细胞经ATRA诱导,出现粒系分化的形态学特征,中幼粒细胞及以后阶段的细胞数明显增多.细胞表面抗原CD71下降而CD13表达升高.ATRA处理组的H-Fn mRNA水平较对照组升高,而IRP2及TfR mRNA减少;处理组IRP结合活性较对照组明显下降,但铁蛋白含量升高.结论 ATRA诱导K562细胞向粒系方向分化过程中,伴有一系列铁代谢相关基因表达产物的改变,其上游调控机制有待进一步探讨.

Iron metabolism in K562 cell differentiation induced by ATRA

Objective To investigate the effects of all trans-retinoic acid (ATRA) on the expressions of iron metabolism-related genes and their products in K562 cells and the possible relationship. Methods (1) The characteristics of K562 leukemic cell differentiation induced by ATRA was evaluated by Benzidine, Wright's, NSE and NBT staining.(2) The expression levels of cellular surface antigens (CD71 and CD 13) in K562 cells cultured with ATRA were measured by flow cytometry. (3) IRP/IRE binding activity was assessed by RNA/protein band-shift assay.(4) Ferritin was determined by radioimmunoassay.(5) The mRNA expression levels of H-Fn, TfR and IRP2 in K562 cells cultured with different concentrations of ATRA were delineated by RT-PCR method, confirmed by sequencing of RT-PCR products. Results K562 cells could be induced to differentiate into neutrophils by ATRA, confirmed by cytochemical staining. The expression of CD71 decreased while CD13 increased. The mRNA expression levels of TfR and IRP2 were decreased while mRNA expression level of H-Fn was increased in K562 cells cultured with ATRA, compared to that in control cells. Concomitantly,IRP binding activity was significantly decreased but the level of ferritin was significantly increased in K562 cells cultured with ATRA. Conclusions During the course of K562 cells induction and differentiation to myelocytes by ATRA, the expression level of iron metabolism-related genes and products were changed but the upstream-regulation mechanism still remains unclear.