一个低丰度表达胃癌下调新基因的克隆及意义

Isolation of a down-regulated novel gene with lower abundance in gastric cancer

目的从成功建立的用于筛选胃癌下调新基因的抑制消减杂交cDNA文库中克隆新基因片段，并行马拉松末端扩增；检测新基因在胃癌及正常胃黏膜组织中的表达，分析该基因与胃癌的相关性。方法随机挑选860个阳性克隆测序，寻找新基因片段。RACE cDNA马拉松末端快速扩增。新基因行Northern印记杂交，并在25例胃癌黏膜与正常胃黏膜RNA进行新基因半定量RT—PCR。新基因行生物信息的分析。结果筛选到一233bp的新基因片段（拷贝数1／860），经cDNA末端快速扩增，得到了长度802bp的新基因。命名为GDDM，被国际GenBank收录，收录号：AF494508。它在胃癌中的表达明显下调（GDDM／β-actin 36．919±6．290 Vs 4．496±0．637，P〈0．01）。染色体定位4q31．1。结论克隆到一胃癌下调低丰度表达新基因GDDM，它可能参与胃癌的发生发展。

Objective To clone novel gene from suppression subtraction library established for screening down-regulated genes in gastric carcinoma, and the effects of novel gene on gastric tumorigenicity were analyzed. Methods Sequencing results of 860 positive colonies chosen randomly were compared by Blast program in GenBank. Novel gene fragment was amplified by rapid amplification of cDNA ends （RACE）. The mRNA expression of novel gene was detected by Northern blot and semi-quantitative PCR in 25 cases of gastric carcinoma tissue and counterpart normal gastric mucosa. The structure and chromosomal location of novel gene were investigated by Bio-message technique. Results A 233 bp novel gene fragment was screened out from 860 clones and a 802 bp novel gene was obtained by RACE. The novel gene was named as GDDM, registered in the number of AF494508 by GenBank. The mRNA expression of GDDM in gastric carcinoma tissue （4.496±0.637） was significantly lower than that in the counterpart normal gastric mucosa （36.919±6.290）（P〈0.01）. Chromosomal location of GDDM gene was at 4q31. Conclusion The cloned novel gene, GDDM, is down-regulated in gastric carcinoma, ant it is likely to be involved in gastric tumorigenicity.