Yuyama Y, Dohi T, Morita H, Furukawa K, Oshima M
Division of Biochemistry and Nutrition, International Medical Center of Japan, Tokyo.
Cancer. 1995 Mar 15;75(6):1273-80. doi: 10.1002/1097-0142(19950315)75:6<1273::aid-cncr2820750609>3.0.co;2-o.
The content of the GM2 ganglioside and the activity of UDP-GalNAc: GM3 beta-1,4N-acetylgalactosaminyltransferase (beta-1,4GalNAcT), which synthesizes GM2, increased in gastric cancer tissues and gastric cancer cell lines as compared with that in normal gastric mucosa.
Expression of beta-1,4GalNAcT mRNA and a concentration of GM2 in the human gastrointestinal tissues were examined. Beta-1,4GalNAcT mRNA in human surgical specimens, which was not detectable with Northern blotting because of the paucity of absolute amounts expressed, was detected with competitive reverse transcription-polymerase chain reaction (PCR) method using an internal standard cRNA that could be amplified by the same primers as target mRNA in PCR. The quantification of GM2 was examined using immunostaining of thin-layer chromatography.
In 10 of 10 gastric carcinomas and 6 of 13 colonic carcinomas, mRNA expression was more enhanced than that in the normal mucosa of each patient. The alteration of GM2 content in carcinoma from normal tissue generally was correlated to the change in the expression of beta-1,4GalNAcT mRNA with a few exceptions. One gastric cancer sample had a higher level of mRNA with a lower GM2 content than the corresponding normal tissue, and two colonic carcinoma tissue specimens had a lower level of mRNA with a higher GM2 content.
These results suggest that expression of the beta-1,4GalNAcT gene is a key step in the molecular mechanisms underlying the regulation of cancer-associated GM2 expression in the stomach and the colon.
与正常胃黏膜相比，胃癌组织和胃癌细胞系中GM2神经节苷脂的含量以及合成GM2的UDP-N-乙酰半乳糖胺：GM3β-1,4-N-乙酰半乳糖胺基转移酶（β-1,4GalNAcT）的活性增加。
检测人胃肠道组织中β-1,4GalNAcT mRNA的表达和GM2的浓度。人手术标本中的β-1,4GalNAcT mRNA由于表达的绝对量很少，无法用Northern印迹法检测到，因此使用竞争性逆转录-聚合酶链反应（PCR）方法，用一种内部标准cRNA进行检测，该cRNA在PCR中可以被与靶mRNA相同的引物扩增。使用薄层色谱免疫染色法检测GM2的定量。
在10例胃癌中的10例以及13例结肠癌中的6例中，mRNA表达比每位患者的正常黏膜中更增强。癌组织中GM2含量相对于正常组织的改变通常与β-1,4GalNAcT mRNA表达的变化相关，但有少数例外。一个胃癌样本的mRNA水平较高，但GM2含量低于相应的正常组织，两个结肠癌组织标本的mRNA水平较低，但GM2含量较高。
这些结果表明，β-1,4GalNAcT基因的表达是胃和结肠中与癌症相关的GM2表达调控分子机制的关键步骤。
