下调组蛋白甲基转移酶EZH2对人胰腺癌细胞RUNX3基因表达及增殖、凋亡的影响

Impact of down-regulation of histone methyltransferase enhancer of zeste homolog 2 on RUNX3 expres- sions, proliferation and apoptosis in human pancreatic cancer

目的研究下调组蛋白甲基转移酶EZH2对人胰腺癌细胞RUNX3基因表达以及增殖、凋亡的影响。方法免疫组化、蛋白印迹检测38例胰腺癌组织以及人胰腺癌AsPC-1、PANC-1、BxPC-3细胞内EZH2和RUNX3表达情况；应用脂质体2000转染siEZH2至细胞内，实时．PCR、蛋白印迹检测EZH2和RUNX3的表达变化；MTF、流式细胞仪及裸鼠成瘤实验体内外观察siEZH2对细胞增殖、凋亡的影响；分析EZH2表达与胰腺癌患者临床病理特点及总存活率的相关性。结果与癌旁组织相比，胰腺癌组织及细胞呈EZH2高表达、RUNX3表达缺失（P〈0．05）；沉默EZH2可明显恢复RUNX3蛋白表达，抑制细胞增殖、促进凋亡，减缓裸鼠体内肿瘤的生长（P〈0．05）；并且EZH2表达与肿瘤分期、淋巴结转移呈正相关，与患者总存活率呈负相关（P〈0．05）。结论EZH2能够抑制RUNX3基因表达，进而促进肿瘤细胞增殖；且与胰腺癌恶性程度及不良预后相关。EZH2可能是胰腺癌的潜在临床治疗靶点。

Objective To investigate the impact of down-regulation of histone methyhransferase enhan- cer of zeste homolog 2 （EZH2） on RUNX3 expressions, proliferation and apoptosis in human pancreatic cancer. Methods The expressions of EZH2 and RUNX3 in 38 pancreatic cancer patients and human pancreatic cancer AsPC-1, PANC-1 and BxPC-3 cells were detected by immunohistochemistry and western blot, respectively. Cells were transfeeted with siEZH2 by lipofectamin 2000. Real time-PCR and western blot were used to detect EZH2 and RUNX3 expressions. Cell growth and apoptosis in vitro and vivo were assessed by MTT, flow cytome- try and nude mice experiments, respectively. The correlation among the expressions of EZH2, clinical pathologi- cal features and overall survival rate were analyzed. Results Elevated EZH2 and decreased RUNX3 expres- sions were observed in human pancreatic cancer tissues and cells （P 〈 0.05 ）. Knockdown of EZH2 reduced cell growth and induced apoptosis in vitro and vivo by upregulating RUNX3 protein expression （ P 〈 0.05 ）. In addi- tion, the EZH2 expressions were correlated with tumor stage, lymph node metastasis and poor prognosis （P 〈 0. 05 ）. Conclusions EZH2 expressions were correlated with malignancy and poor prognosis in pancreatic cancer. Tumor cell proliferation was promoted by EZH2 through down-regulation of RUNX3. EZH2 may be a potential therapeutic target for pancreatic cancer.