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[摘要]
目的:观察表达异种鸡EGFR(chicren EGFR, cEGFR)与 IgGγFc融合基因的口服减毒鼠伤寒沙门菌疫苗对高表达EGFR 的肺癌Lewis细胞小鼠移植瘤生长的抑制作用。方法:将pVAX1-cEGFR-γFc质粒转化减毒沙门菌SL7207,重组菌SL7207/pVAX1-cEGFR-γFc体外感染小鼠腹腔巨噬细胞,免疫荧光法检测cEGFR-γFc融合蛋白的表达。SL7207/pVAX1-cEGFR-γFc重组菌口服免疫小鼠3次后接种Lewis细胞,Western blotting检测小鼠体内融合蛋白的表达,ELISA法检测免疫小鼠血清抗EGFR抗体的水平。接种Lewis细胞14 d后处死小鼠,瘤体称质量,检测SL7207/pVAX1-cEGFR-γFc疫苗对Lewis肺癌生长的抑制作用,测定荷瘤小鼠的生存时间。结果:成功构建减毒沙门菌疫苗SL7207/pVAX1-cEGFR-γFc,SL7207/pVAX1-cEGFR-γFc感染后,在小鼠后体内外都能检测到cEGFR-γFc融合蛋白的表达;SL7207/pVAX1-cEGFR-γFc疫苗口服免疫后小鼠能够产生高水平的抗EGFR抗体,口服SL7207/pVAX1-cEGFR-γFc疫苗能够有效抑制小鼠Lewis移植瘤的生长,延长荷瘤小鼠的生存时间。结论:异种EGFR口服DNA疫苗能够有效地抑制高表达EGFR肺癌的生长,是EGFR分子靶向治疗的一条新途径。
[Key word]
[Abstract]
Objective:To investigate the inhibitory effect of attenuated salmonella typhimurium vaccine, which expressing xenogeneic chicken EGFR and IgG γFc, on the growth of Lewis lung cancer (expressed high level of EGFR)-implanted tumors in mice. Methods: pVAX1/ cEGFR-γFc plasmid was transformed into attenuated salmonella typhimurium strain SL7207, and the resultant SL7207/pVAX1-cEGFR-γFc bacteria were used to infect murine peripheral macrophage in vitro. Then expression of cEGFR-γFc fusion protein was detected by immunofluorescent assay. Mice were immunized with SL7207/pVAX1-cEGFR-γFc for 3 times, and then inoculated with Lewis cells. Expression of cEGFR-γFc fusion protein in mice tissue was detected by Western blotting analysis, and serum anti-EGFR level was determined by ELISA method. The weight of implanted Lewis tumor was measured after 14 d to investigate the anti-tumor effect of SL7207/pVAX1-cEGFR-γFc vaccine, and the survival time of tumor-bearing mice was also examined. Results: The attenuated salmonella typhimurium DNA vaccine SL7207/pVAX1- cEGFR-γFc was successfully constructed. The cEGFR-γFc fusion protein could be expressed in mouse cells after SL7207/pVAX1-cEGFR-γFc infection in vitro and in vivo. The mice immunized with SL7207/pVAX1-cEGFR-γFc could produce high level of anti-EGFR antibody. The tumor growth was obviously inhibited and the survival time of tumor-bearing mice was also increased in the SL7207/pVAX1-cEGFR-γFc vaccine group. Conclusion: The DNA vaccine expressing xenogeneic EGFR can effectively inhibit the growth of EGFR-positive tumors, which is a new EGFR-targeting therapy strategy.
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[基金项目]
上海市科委基金资助项目(No. 03DZ19263); 上海市普陀区卫生局资助项目(No.PTW08-Z01)