VIB Center for Inflammation Research, 9052 Ghent, Belgium.
Unit for Structural Biology, Department of Biochemistry and Microbiology, Ghent University, 9052 Ghent, Belgium.
Sci Adv. 2021 Mar 26;7(13). doi: 10.1126/sciadv.abe1682. Print 2021 Mar.
The therapeutic scope of antibody and nonantibody protein scaffolds is still prohibitively limited against intracellular drug targets. Here, we demonstrate that the Alphabody scaffold can be engineered into a cell-penetrating protein antagonist against induced myeloid leukemia cell differentiation protein MCL-1, an intracellular target in cancer, by grafting the critical B-cell lymphoma 2 homology 3 helix of MCL-1 onto the Alphabody and tagging the scaffold's termini with designed cell-penetration polypeptides. Introduction of an albumin-binding moiety extended the serum half-life of the engineered Alphabody to therapeutically relevant levels, and administration thereof in mouse tumor xenografts based on myeloma cell lines reduced tumor burden. Crystal structures of such a designed Alphabody in complex with MCL-1 and serum albumin provided the structural blueprint of the applied design principles. Collectively, we provide proof of concept for the use of Alphabodies against intracellular disease mediators, which, to date, have remained in the realm of small-molecule therapeutics.
抗体和非抗体蛋白支架的治疗范围仍然受到限制，无法针对细胞内药物靶点。在这里，我们证明了 Alphabody 支架可以通过将 MCL-1 的关键 B 细胞淋巴瘤 2 同源性 3 螺旋嫁接在 Alphabody 上，并在支架的末端标记设计的细胞穿透多肽，从而被工程化为针对诱导髓系白血病细胞分化蛋白 MCL-1（癌症中的一种细胞内靶点）的穿透细胞蛋白拮抗剂。引入白蛋白结合部分将工程化的 Alphabody 的血清半衰期延长至治疗相关水平，并且在基于骨髓瘤细胞系的小鼠肿瘤异种移植中给予其可降低肿瘤负担。与 MCL-1 和血清白蛋白结合的这种设计的 Alphabody 的晶体结构提供了应用设计原则的结构蓝图。总的来说，我们提供了使用 Alphabody 对抗细胞内疾病介质的概念验证，迄今为止，这些介质仍处于小分子治疗的领域。
