异种EGFR口服DNA疫苗抑制小鼠Lewis肺癌的生长

Oral DNA vaccine expressing xenogeneic EGFR inhibits growth of Lewis lung cancer in mice

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-cEG-FR-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-cEG-FR-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。

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.