Bie Nana, Zhao Xiuyun, Li Zhitao, Qi Gaofu
College of Life Science and Technology, Huazhong Agricultural University, Wuhan, HuBei Province, P.R. China.
J Immunother. 2016 Sep;39(7):260-8. doi: 10.1097/CJI.0000000000000129.
Most of tumor antigens are self-proteins with poor antigenicity because of immune tolerance. Here, we describe DNA shuffling for overcoming the tolerance of tumor antigens such as vascular endothelial growth factor (VEGF), a growth factor associated with tumor angiogenesis. VEGF genes from mouse, rat, human, and chicken were randomly assembled to chimeric genes by DNA shuffling for constructing an expression library, then screened by PCR, SDS-PAGE, and immunization. A chimeric protein named as No. 46 was selected from the library with the strongest immunotherapy effects on mouse H22 hepatocellular carcinoma, which could induce long-lasted and high level of antibodies recognizing VEGF in mice. Immunization with this chimeric protein could significantly inhibit tumor angiogenesis, slow down tumor growth, increase the survival rate of tumor-bearing mice, and inhibit the lung metastases of tumor in mouse. Treatment with the anti-VEGF IgG induced by this chimeric protein also significantly inhibited tumor growth and improved the survival rate of tumor-bearing mice, by blocking the tyrosine phosphorylation of ERK1/2 pathway of VEGF-VEGFR interaction. Our study provides an efficient approach to overcome the immune tolerance of self-antigens for developing novel tumor vaccines.
由于免疫耐受，大多数肿瘤抗原都是抗原性较差的自身蛋白。在此，我们描述了一种用于克服肿瘤抗原免疫耐受的DNA改组技术，例如血管内皮生长因子（VEGF），一种与肿瘤血管生成相关的生长因子。通过DNA改组将来自小鼠、大鼠、人类和鸡的VEGF基因随机组装成嵌合基因，以构建一个表达文库，然后通过PCR、SDS-PAGE和免疫进行筛选。从该文库中筛选出一种名为46号的嵌合蛋白，它对小鼠H22肝癌具有最强的免疫治疗效果，能够在小鼠体内诱导产生持久且高水平的识别VEGF的抗体。用这种嵌合蛋白进行免疫可显著抑制肿瘤血管生成，减缓肿瘤生长，提高荷瘤小鼠的存活率，并抑制小鼠肿瘤的肺转移。由这种嵌合蛋白诱导产生的抗VEGF IgG进行治疗，也通过阻断VEGF-VEGFR相互作用的ERK1/2途径的酪氨酸磷酸化，显著抑制了肿瘤生长并提高了荷瘤小鼠的存活率。我们的研究为开发新型肿瘤疫苗提供了一种克服自身抗原免疫耐受的有效方法。
