中文摘要：

STGC3基因是一个新近克隆的肿瘤相关基因，前期的体外实验研究结果表明，STGC3基因在CNE2鼻咽癌细胞系高表达，可明显抑制CNE2的生长增殖．采用Tet／p TRE-STGC3／CNE2细胞系接种于裸鼠皮下，以强力霉素（Dox）诱导STGC3基因高表达，观测STGC3基因高表达对CNE2裸鼠体内成瘤的影响，并探讨其可能作用机制．运用RT-PCR、蛋白质印迹及免疫组织化学方法，分别从mRNA和蛋白质水平，分析瘤组织中STGC3基因的表达；用流式细胞仪检测移植瘤组织内肿瘤细胞的凋亡情况；用免疫组织化学方法，检测移植瘤组织凋亡相关蛋白Bcl-2和Bax的表达．研究结果显示，STGC3蛋白表达主要定位于细胞核内，Dox诱导STGC3基因在Tet／p TRE-STGC3／CNE2细胞系高表达，Tet／pTRE-STGC3／CNE2细胞系裸鼠体内成瘤受到明显抑制，与对照组比较，移植瘤成瘤时间晚、生长慢、肿块小、细胞凋亡率高，Bax蛋白表达增强，Bcl-2蛋白表达减少，差异有显著性意义（P〈0．01）．此体内实验研究结果与前期体外实验结果一致，进一步证明STGC3基因对肿瘤细胞生长具有抑制作用．

英文摘要：

STGC3, a novel tumor related gene, was cloned recently. The previous studies indicated that STGC3 can inhibit the proliferation of CNE2 cell line in vitro. To examine the effect of STGC3 on the tumorigenicity of CNE2 cell line and explore its mechanism in nude mice. The Tet/pTRE/CNE2-STGC3 cell line was planted under the front leg skin of nude mice and induced by doxycycline （Dox）. The mRNA and protein level of STGC3 in transplanted tumor tissues were detected with RT-PCR and Western Blotting. The apoptosis ratio of the tumor cell was analyzed with flow cytometry. STGC3, Bcl-2 and Bax proteins were examined by immunohistochemistry method. The results indicated that high level of STGC3 expression can inhibit tumorigenicity of CNE2 cell line in nude mice. Tumor grew slowly, later and smaller. Cell apoptotic percentage increased. Bcl-2 protein expression was down-regulated and Bax protein expression was up-regulated in Tet/pTRE/CNE2-STGC3 cell line （P 〈 0.01）. The data indicated that STGC3 had a role as a tumor suppressor gene in vivo, which was in line with the results in vitro.