中文摘要：

目的：研究CCAAT/增强子结合蛋白α（CCAAT/enhancer-binding protein-alpha,C/EBPα）对K562细胞株分化和凋亡的影响及对相关基因的调控,为慢性粒细胞白血病的治疗提供新的治疗靶点。方法：将C/EBPα表达质粒pEGFP-C/EBPα及空载体对照质粒pEGFP分别经阳离子脂质体2000介导转染K562细胞,用G418筛选出C/EBPα稳定表达细胞株。Wright-Giemsa染色观察细胞形态学变化,FCM分析细胞表面分化抗原CD11b的表达、细胞周期及细胞凋亡,电子显微镜观察细胞凋亡,RT-PCR和Western印迹法检测细胞中相关基因Per2、cyclin B1和C-myc的表达。结果：筛选得到稳定表达C/EBPα的细胞株pEGFP-C/EBPα-K562。与空载体转染组及对照组细胞相比,转染组K562细胞分化明显,同时粒系细胞表面分化抗原CD11b表达增加;细胞周期分析发现,转染组细胞中G2期细胞增多,与空载体组和对照组相比,差异有统计学意义（P〈0.05）,同时出现细胞凋亡峰。细胞凋亡检测结果显示,转染组细胞凋亡明显增加（21.1%）,与空载体组（6.0%）和对照组（4.2%）比较,差异有统计学意义（P〈0.05）;电子显微镜观察发现,转染组细胞中出现染色质浓集、断裂和核固缩等现象,并见凋亡小体;RT-PCR和Western印迹法检测发现,C/EBPα明显上调Per2 mRNA和蛋白表达,抑制cyclinB1、C-myc mRNA和蛋白的表达。结论：C/EBPα能促进K562细胞分化,并诱导细胞凋亡,其机制可能是通过对细胞周期相关基因的调控来实现的。

英文摘要：

Objective：To investigate the effects of CCAAT/enhancer-binding protein alpha （C/EBPα） on differentiation and apoptosis of K562 cells and regulation of coherent genes, and provide a new therapeutic target for chronic myelogenous leukemia. Methods：The C/EBPα expression plasmid pEGFP-C/EBPα and empty control plasmid were transfected into K562 cells mediated by cationic liposome 2000, respectively. The resistant cells stably expressing the C/EBPα gene were screened by G418 selection. The morphological changes were observed under light microscope after Wright-Giemsa staining; flow cytometry was performed to analyze the expression of the differentiation antigen CD11b, cell cycle distribution, and apoptosis; the electron microscopy was used to observe cell apoptosis; RT-PCR and Western blotting were used to detect the expression of coherent genes such as Per 2, cyclin B1, and C-myc at the mRNA and protein levels, respectively. Results：This study obtained the pEGFP-C/EBPα-K562 cell line with stable expression of the C/EBPα gene by G418 screening. As compared with either the empty plasmid transfected-group or the control group, pEGFP-C/EBPα-K562 cells differentiated obviously and the expression of differentiation antigen CD11b was up-regulated. Cell cycle analysis showed that the percentage of K562 cells in G2 phase was increased. The difference was significant compared with empty plasmid transfection group and control group （P〈0.05）. Distinguished apoptotic peak appeared simultaneously. Flow cytometry showed more apoptotic cells in the C/EBPα gene transfected group （21.1%） as compared with either the empty plasmid transfected group （6.0%） or control group （4.2%）. The difference was significant （P〈0.05）. Electron microscopy observed chromatin condensation, DNA fragmentation, karyopycnosis, and apoptotic bodies in K562/C/EBPα group. RT-PCR and Western blotting showed that C/EBPα significantly up-regulated Per 2 mRNA and protein expressions, while down-regulated cyclinB1 and C-myc