抑癌候选基因NDRG2在结肠癌组织中的表达

目的分析抑癌候选基因NDRG2在人类结肠肿瘤组织中的表达情况。方法收集30例患者的结肠癌组织及其正常组织，提取总RNA，应用半定量反转录-聚合酶链反应（RT-PCR）检测NDRG2 mRNA的表达水平。为进一步分析NDRG2蛋白质的表达水平，分别提取30例组织的总蛋白，应用蛋白质印迹和免疫组织化学（免疫组化）技术检测其NDRG2的蛋白表达水平。结果RT-PCR结果显示，30例结肠癌组织中，有12例的NDRG2 mRNA表达明显降低。蛋白印迹结果显示，30例结肠肿瘤组织中有12例NDRG2蛋白水平明显下降，与RT-PCR结果一致。免疫组化结果显示，正常组织及肿瘤组织中NDRG2阳性率分别为90．0％（27／30）和53．3％（16／30），组间阳性表达率差异有统计学意义（P〈0．05），NDRG2的表达与患者的年龄、性别、淋巴结转移、浸润深度、Dukes分期无明显相关关系（P〉0．05），而与肿瘤组织分化级别相关，高、中分化组NDRG2阳性表达率高于低分化组（P〈0．05）。结论NDRG2在某些结肠癌组织中呈低表达，而且其表达与结肠癌的分化程度有关，提示其可能对结肠癌的发生或发展有重要的作用。这为研究结肠癌的发病机制提供了进一步的线索。

Expression of candidate tumor suppressor gene N-Myc downstream-regulated gene 2 in colon cancer

OBJECTIVE: To analyze the expression level of candidate tumor suppressor gene N-Myc downstream-regulated gene 2 (NDRG2) in human colon cancer. METHODS: Thirty samples of colon cancer tissues with matched normal colon tissues were collected. The NDRG2 mRNA level was detected by semi-quantitive RT-PCR and the NDRG2 protein level was examined by Western blot and immunohistochemistry. RESULTS: Twelve samples of colon cancer tissues had low NDRG2 mRNA level and low protein level. The positive rates of NDRG2 in normal tissues and the tumorous colon tissues were 90.0%(27/30) and 53.3%(16/30) by immunohistochemistry respectively. There was a significant difference between two groups (P<0.05). The NDRG2 expression was not correlated with age, sex, metastasis of lymph node, depth of infiltration, as well as the Dukes staging(P>0.05), while it was correlated to the histology grading. The positive rate of NDRG2 in the well- and moderate-differentiation group was higher than that in the poor-differentiation group(P<0.05). CONCLUSION: The expression of NDRG2 is low in some colon cancer tissues, which indicates that the low level of NDRG2 expression may be engaged in the development of colon cancer.