Nojima D, Nakajima K, Li L C, Franks J, Ribeiro-Filho L, Ishii N, Dahiya R
Department of Urology, Veterans Affairs Medical Center and University of California San Francisco, 94121, USA.
Mol Carcinog. 2001 Sep;32(1):19-27. doi: 10.1002/mc.1060.
CpG methylation in the promoter region has been shown to be important in the regulation of genes implicated in malignant transformation. The present study was designed to test the hypothesis that CpG methylation of the promoter region of the E-cadherin gene may inactivate its expression in renal cell carcinoma. To test this hypothesis, five kidney cancer cell lines and 34 microdissected renal cell carcinoma samples were analyzed for gene and protein expression by reverse transcription-polymerase chain reaction and immunohistochemistry, respectively. CpG methylation in the promoter regions of the E-cadherin gene was analyzed by the sodium bisulfite genome sequencing technique. Our results show that all normal renal tissue expressed the E-cadherin gene and protein. Of the renal cancer tissues analyzed, 67% (23 of 34) lacked E-cadherin expression, with an associated increase in methylation, compared with normal tissue. E-cadherin gene promoter was methylated in all renal cancer cell lines and was accompanied by a loss of E-cadherin gene and protein expression. The treatment of renal cancer cell lines with the demethylating agent 5-aza-2'-deoxycytidine restored E-cadherin mRNA expression in all renal cancer cell lines. This is the first report that shows inactivation of the E-cadherin gene and protein in renal cell carcinoma through CpG hypermethylation in the promoter region of this gene. The results of these experiments may contribute to an understanding of the role of E-cadherin inactivation in renal cell carcinoma.
启动子区域的CpG甲基化已被证明在调控与恶性转化相关的基因中起重要作用。本研究旨在验证以下假设：E-钙黏蛋白基因启动子区域的CpG甲基化可能使其在肾细胞癌中表达失活。为验证这一假设，分别采用逆转录-聚合酶链反应和免疫组织化学方法，对5种肾癌细胞系和34个显微切割的肾细胞癌样本进行了基因和蛋白表达分析。采用亚硫酸氢钠基因组测序技术分析了E-钙黏蛋白基因启动子区域的CpG甲基化情况。我们的结果显示，所有正常肾组织均表达E-钙黏蛋白基因和蛋白。在分析的肾癌组织中，67%（34个样本中的23个）缺乏E-钙黏蛋白表达，与正常组织相比，甲基化水平相应增加。所有肾癌细胞系中E-钙黏蛋白基因启动子均发生甲基化，同时伴有E-钙黏蛋白基因和蛋白表达缺失。用去甲基化剂5-氮杂-2'-脱氧胞苷处理肾癌细胞系后，所有肾癌细胞系中E-钙黏蛋白mRNA表达均得以恢复。这是首份显示通过该基因启动子区域的CpG高甲基化使肾细胞癌中E-钙黏蛋白基因和蛋白失活的报告。这些实验结果可能有助于理解E-钙黏蛋白失活在肾细胞癌中的作用。
