EGFRvⅢ与HBcAg重组疫苗抗肿瘤作用的实验研究

目的:观察PEP-3/HBcAg融合蛋白疫苗的体内抗肿瘤作用。方法:BALB/c小鼠30只随机分成3组,分别接种PEP-3/HBcAg融合蛋白、HBcAg和生理盐水,待融合蛋白组小鼠体内抗体效价达到1:20000时终止免疫,于每只小鼠背部皮下种植阳性Renca细胞,2×105个/只。观察融合蛋白疫苗的抗肿瘤效应。采用HE染色和免疫组织化学图像分析法检测各组肿瘤组织的坏死情况和EGFRvIII表达水平。结果:融合蛋白组、HBcAg组和生理盐水组的成瘤率分别为50%、100%和100%。生理盐水组肿瘤生长速度最快,HBcAg组次之,融合蛋白组肿瘤出现最晚,生长速度最慢。融合蛋白组成瘤小鼠肿瘤平均质量显著小于生理盐水组和HBcAg组(t=4·731,P=0·044;t=6·890,P=0·040);后两组肿瘤质量无统计学意义(t=0·024,P=0·382)。HBcAg组和生理盐水组移植瘤呈不完全小片状坏死,融合蛋白组移植瘤呈大片状坏死,伴炎细胞浸润。融合蛋白组EGFRvⅢ表达水平明显低于生理盐水组和HBcAg组(t=3·157,P=0·006;t=2·539,P=0·021),后两者EGFRvIII表达水平无统计学差异(t=0·460,P=0·651)。结论:PEP-3/HBcAg融合蛋白疫苗能诱导机体产生保护性免疫反应,并具有抗肿瘤作用。

Antitumor effect of EGFRvⅢ/HBcAg recomibinant vaccine on murine transplanted tumor

AIM: To explore the immune effect of the recomibinant fusion protein EGFRvIII/HBcAg on murine transplanted EGFRvIII positive tumor in vivo. METHODS: BALB/c mice(30) were ramdomedly divided into three groups and immunized by fusion protein, HBcAg and normal sodium(NS). When the antibody titre of the mice immunized by fusion protein reached 1:20 000, the immunization was terminated and the positive renca cells of EGFRvIII were inoculated subcutaneouly into BALB/c mice. The antitumor effect was observed in vivo. Using HE and immunohistochemistry image analysis, the tumor necrosis and EGFRvIII expression were compared among three groups. RESULTS: Tumor growth was inhibited by fusion protein. The tumorigenic rate of fusion protein group, HBcAg group and NS group was 50%, 100% and 100% respectively. Tumor grew fastest in NS group but tumor grew with the slowest speed in fusion protein group. The average tumor weight of fusion protein group was significantly lighter than that of the other two groups (t=4.731, P=0.044; t=6.890, P=0.040), and there was no statistical difference between normal sodium group and HBcAg group (t=0.024, P=0.382). Tumor necrosis was much severe in fusion group. Immunohistochemistry analysis showed that the expression level of EGFRvIII in fusion protein group was lower than that in NS group and HBcAg group(t=3.157, P=0.006; t=2.539, P=0.021), and no statistical difference was observed between the two groups(t=0.460, P=0.651). CONCLUSION: The fusion protein EGFRvIII/HBcAg can induce the protective antitumor immunity against EGFRvIII-positive tumor.