中文摘要：

目的构建人中期因子（MDK）基因重组逆转录病毒载体，转染人胃癌SGC7901细胞株，为探讨MDK的生物学功能奠定基础。方法扩增人MDK编码序列基因片段，经限制性内切酶酶切后将目的片段插入pLXSN逆转录病毒载体。经酶切及测序鉴定后与pVSVG共转染GP293包装细胞，收集病毒上清感染人胃癌SGC7901细胞，G418筛选获得阳性细胞株。结果酶切及DNA测序证实MDK基因重组逆转录病毒载体构建正确。病毒上清感染SGC7901细胞，G418筛选出阳性克隆，经实时定量PCR及Western blot检测发现SGC7901细胞中MDKmRNA及蛋白表达水平明显上调。结论成功构建了高表达MDK的SGC7901细胞株，为进一步探讨其生物学功能奠定实验基础。

英文摘要：

Objective To construct the recombinant retroviral vector of human midkine （MDK） gene and to transfect the vector into gastric cancer cell line SGC7901. Methods Human MDK cDNA was amplied from BGC823 cell line by high fidelity PCR. Retroviral vector pLXSN carrying MDK cDNA was constructed, and the retroviral producer cell line GP293 was developed by liposome-mediated transfection. SGC7901 cells were transfected with pLXSN-MDK virus and screened by G418. The expression of MDK was detected by real-time PCR and Western blot. Results The retroviral vector pLXSN-MDK was successfully constructed and infected SGC7901 cells,and MDK gene expression was up-regulated in SGC7901/pLXSN-MDK cells. Conclusion SGC7901/pLXSN-MDK gastric cancer cells can be used for the further study on the biological function of MDK.