人4-1BBL胞外区/抗CD20 Fab’融合蛋白的构建和表达

研究共刺激分子4-1BBL在肿瘤靶向治疗方面的作用, 用PCR 和overlap PCR 方法构建人4-1BBL胞外区/抗CD20 Fab’融合蛋白表达载体, 并用双脱氧终止法测定DNA 序列; 采用亲和层析法纯化该产物, 并用SDS-PAGE和HPLC鉴定纯化产物; 采用玫瑰花环试验鉴定纯化产物与靶细胞的结合活性。DNA 序列测定结果表明: 人4-1BBL胞外区/抗CD20 Fab’融合蛋白已构建成功。表达可溶性产物的产量达200 mg/L以上, 纯度较高, 具有与激活的Jurkat (4-1BBL+) 和Raji细胞(CD20+)结合的活性。这将为非何杰金氏淋巴瘤免疫治疗、靶向治疗提供新的思路。

Study on the Construction and Expression of the Human 4-1BBL Extracellular Domain/anti-CD20 Fab' Fusion Protein

Several studies have demonstrated the role of 4-1BBL in T cell activation. Furthermore, enhanced 4-1BB/4-1BBL interaction has been shown to amplify T-cell-mediated antitumor immunity in several mouse models. However, when applied in humans, it was difficult to generate sufficient T cells ex vivo and whole cell vaccines to transfer back into patients. To overcome this difficulty, we have focused on producing the human 4-1BBL extracellular domain/anti-CD20 Fab' fusion protein. In this report, PCR and overlap PCR were used to construct the human 4-1BBL extracellular domain/anti-CD20 Fab' expression vector. DNA sequence was analyzed by the Terminus of Dideoxy Nucleotide. The product was purified by affinity chromatography and analyzed by SDS-PAGE and HPLC; its antigen binding activity was examined by rosetting assay. The data of DNA sequence showed that the human 4-1BBL extracellular domain/anti-CD20 Fab' fusion protein was corrected. The fusion protein was recovered in high yield (up to 200 microg/mL) after E-taq purification. The fusion protein was capable of simultaneous binding to stimulated Jurkat cells and Raji cells as shown by cellular rosetting. In conclusion, the human 4-1BBL extracellular domain/anti-CD20 Fab' fusion protein was induced to express in E. coli 16C9. The results of some biological activity experiments indicated that the fusion protein could bind to stimulated Jurkat cells and Raji cells. Furthermore, 4-1BBL-negative tumors can be converted into 4-1BBL-positive tumors by the fusion protein without the need for 4-1BBL gene transfer to the malignant cells.