Chen Y M, Shiu J Y, Tzeng S J, Shih L S, Chen Y J, Lui W Y, Chen P H
Division of Preventative Medicine, Institute of Public Health, School of Medicine, National Yang-Ming University, Taipei, Taiwan, Republic of China.
Int J Cancer. 1998 Mar 2;75(5):787-93. doi: 10.1002/(sici)1097-0215(19980302)75:5<787::aid-ijc20>3.0.co;2-2.
Messenger RNA differential display was used to study liver-gene expression in paired tumor and non-tumor tissues from hepatocellular carcinoma (HCC) patients. mRNA differential display and Northern-blot analyses showed that a 0.8-kb cDNA fragment was diminished or absent from the tumorous tissues of 7 HCC patients. The cDNA fragment was sequenced and found to have 98.7% nucleotide sequence homology with human glycine-N-methyltransferase cDNA (GNMT). In addition, there was no detectable level of GNMT expression in 4 human HCC cell lines, SK-Hep1, Hep 3B, HuH-7 and HA22T, examined by Northern-blot assay. A full-length GNMT cDNA clone-9-1-2 was obtained by screening a Taiwanese liver cDNA library. In comparison with the GNMT cDNA sequence reported elsewhere, clone 9-1-2 had 4 nucleotide differences resulting in 1 amino-acid change. Immunohistochemical staining with rabbit anti-recombinant GNMT serum showed that GNMT protein almost completely disappeared in liver-cancer cells, while it was abundant in the non-tumorous liver cells. Down-regulation of GNMT gene expression may be involved in the pathogenesis of liver cancer.
运用信使核糖核酸差异显示技术，研究肝细胞癌（HCC）患者配对的肿瘤组织和非肿瘤组织中的肝脏基因表达。信使核糖核酸差异显示和Northern杂交分析表明，7例HCC患者的肿瘤组织中一个0.8kb的互补脱氧核糖核酸片段减少或缺失。对该互补脱氧核糖核酸片段进行测序，发现其与人类甘氨酸-N-甲基转移酶互补脱氧核糖核酸（GNMT）具有98.7%的核苷酸序列同源性。此外，通过Northern杂交分析检测发现，在4种人类肝癌细胞系SK-Hep1、Hep 3B、HuH-7和HA22T中未检测到GNMT表达水平。通过筛选台湾肝脏互补脱氧核糖核酸文库获得了全长GNMT互补脱氧核糖核酸克隆9-1-2。与其他地方报道的GNMT互补脱氧核糖核酸序列相比，克隆9-1-2有4个核苷酸差异，导致1个氨基酸变化。用兔抗重组GNMT血清进行免疫组织化学染色显示，GNMT蛋白在肝癌细胞中几乎完全消失，而在非肿瘤肝细胞中含量丰富。GNMT基因表达下调可能与肝癌的发病机制有关。
