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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 observe the inhibitory effect of oral attenuated Salmonella typhimurium vaccine expressing chimeric EGFR (cEGFR) and IgGγFc fusion gene on the growth of transplanted Lewis lung carcinoma in mice bearing EGFR-overexpressing EGFR. Methods: Plasmids pVAX1-cEGFR-γFc were transformed into attenuated Salmonella typhimurium SL7207 and the recombinant strain SL7207 / pVAX1-cEGFR-γFc was infected in vitro. The expression of cEGFR-γFc fusion protein was detected by immunofluorescence. Lewis cells were inoculated three times with SL7207 / pVAX1-cEG-FR-γ-Fc recombinant plasmids. The expression of fusion protein was detected by Western blotting, and the level of serum anti-EGFR antibody was detected by ELISA. The mice were sacrificed 14 days after inoculation of Lewis cells. The tumor mass was weighed and the growth inhibition of Lewis lung carcinoma was detected by SL7207 / pVAX1-cEGFR-γ Fc vaccine. The survival time of tumor-bearing mice was determined. Results: After inoculated with attenuated Salmonella typhimurium vaccine SL7207 / pVAX1-cEGFR-γFc and SL7207 / pVAX1-cEG-FR-γFc, the expression of cEGFR-γFc fusion protein was detected both in vitro and in vivo. The mice immunized with -cEGFR-γFc vaccine could produce high levels of anti-EGFR antibodies. Oral SL7207 / pVAX1-cEGFR-γFc vaccine can effectively inhibit the growth of Lewis xenografts in mice and prolong the survival of tumor-bearing mice. Conclusion: Oral EGFR oral DNA vaccine can effectively inhibit the growth of EGFR-overexpressing lung cancer, which is a new way of molecular targeted therapy of EGFR.