Tumstatin-CD137L融合蛋白的分子改构及成药性研究

由于外源重组蛋白在体内快速降解、体内循环半衰期短，已成为制约重组蛋白成药的主要因素之一。现有延长蛋白质药物半衰期的策略均存在不同程度的缺陷，研究蛋白质药物的新型长效化手段迫在眉睫。本课题组前期构建的兼具抑制肿瘤微环境血管再生和激活机体免疫应答的双功能融合蛋白Tumstatin-CD137L，同样存在体内半衰期短这一严重缺陷。因此，针对Tumstatin-CD137L双功能融合蛋白体内半衰期短这一决定成药性的关键制约因素，本课题拟采用遗传密码扩充技术和本课题独创的D型氨基酸定点引入技术对融合蛋白中涉及体内稳定性的关键氨基酸位点进行系统改造而引入非天然或D型氨基酸，预期在保留或提高重组Tumstatin-CD137L融合蛋白的抗肿瘤活性基础上，有效延长体内半衰期，为改善蛋白质药物的成药性提供新的策略和手段。

Due to the rapid degradation of recombinant proteins in vivo, the short half-life in the circulation has become one of the major obstacles to limit the development of recombinant proteins as therapeutic agents. Given different degrees of shortcomings with current strategies, it is urgent and essential to develop new techniques to prolong the half-life of therapeutic proteins. The bifunctional recombinant Tumstatin-CD137L proteins that we previously constructed could inhibit angiogenesis in the tumor microenvironment and activate the immune response, also have this serious issue on the short in vivo half-life. To address this important question associated with the druggability of Tumstatin-CD137L proteins, the present study will employ the techniques of genetic code expansion and our newly developed D-amino acid incorporation to redesign and reconstruct the recombinant Tumstatin-CD137L proteins, in which the stability-related amino acid residues will be systematically mutated to unnatural or D-amino acids to prevent degradation. The desired proteins will not only maintain or increase their antitumor activity, but also exhibit prolonged in vivo half-lives. This investigation will provide a new strategy and effective tools to improve the druggability of therapeutic fusion proteins.