IL-12瘤苗联合放疗对小鼠Lewis肺癌作用研究

The Studies onEffects of the Interleukin-12 Tumor Vaccine plus Radiotherapy of Murine Lewis Lung Cancer

目的:建立稳定表达小鼠IL-12(Murine interleukin-12,mIL-12)的小鼠Lewis肺癌(Lewis lung carcino-ma,LLC)瘤苗LLC/mIL-12,评估瘤苗对荷鼠Lewis肺癌C57BL/6小鼠的放疗增敏作用。方法:重组质粒pcD-NA3.1(+)-mIL-12用脂质体转染LLC,G418筛选后获得LLC/mIL-12瘤苗。C57BL/6小鼠皮下接种LLC细胞2×106,成瘤后将小鼠随机分成4组(n=10),第0、7、14d瘤苗组和联合组瘤内注射瘤苗,第1、3、5d放疗和联合组给予2Gy局部照射。第21d处死小鼠,观察肿瘤体积、脾细胞中CTL和NK活性以及肿瘤细胞凋亡。结果:联合组肿瘤体积显著缩小,NK和CTL活性增强,凋亡增加,与其它组相比,P<0.05;放疗组NK和CTL活性降低。结论:LLC/mIL-12瘤苗及放疗均能产生抗瘤反应,且联合组作用更强。瘤苗放疗增敏作用机制是诱导细胞凋亡,增强NK和CTL活性。

Objective： To test LLC/mIL-12, a tumor vaccine for murine Lewis lung carcinoma （LLC）, and to assess radiosensitization of the murine LLC cells after transfection with the murine IL-12 gene in Lewis lung tumor-bearing mice. Methods： The recombinant plasmid pcDNA3.1 （＋） -miL-12 was transfected into the LLC cells via liposome, and then clones positive for LLC/ miL-12 were obtained by screening with G418. Hypodermic inoculation of 2×10^6 LLC cells into the C57BL/6 mice （n=10） was conducted and the mice were randomized into 4 groups after tumorigenesis. The tumor vaccine was administered to the vaccine group and the combination group on day 0, 7 and 14, and local irradiation with 2Gy was administered in the radiotherapy group and the combination group on day 1, 3 and 5. The mice were sacrificed on day 21, and the tumor size, the activity of cytotoxic T lymphocytes （CTL） and natural killer cells （NK）, and the apoptotic activity of the tumor cells were observed. Results： In the combined group the size of tumors was significantly smaller, activity of the NK and CTL was enhanced, and apoptosis was increased, compared to the other groups （P〈0.05）. The activity of the NK and CTL in the radiotherapy group was reduced. Conclusion： Antitumor immune response can be induced in the radiotherapy group and the LLC/mIL-12 vaccine group, but it is much stronger in the combination group. The mechanism of vaccine radiosensitization includes induction of cell apoptosis and enhancement of NK and CTL activity.