光引发巯基-炔点击化学构建低脱靶双环稳定多肽体系及其生物学应用

Peptides have drawn wide attention for being able to modulate pivotal protein-protein interactions involved in cancer. However, linear peptides suffer from rapid degradation in vivo and are generally lack of cell permeability and cellular activities. Stapled peptides, one of the representative macrocyclic peptidomimetics, could efficiently penetrate cell membrane to access intracellular targets, thus are considered as next generation of therapeutics. However, stapled peptides display insufficient tumor targeting. And the off-target issue in terms of non-specific toxicity induced by the hydrophobic cross-links has largely reduced the safety for their clinical translation. To address these issues, novel bicyclic peptide scaffolds with low off-target toxicity and the ability for dual-targeting of both overexpressed receptors on the cell surface and aberrant intracellular protein-protein interactions are highly desired within the same scaffold. To also address the stability issue of linear peptide ligand for tumor targeting, this project is to: 1. Develop novel alkyl di-thioether cross-linked bicyclic peptide scaffolds with low off-target toxicity via photo-induced thiol-yne click chemistry; 2. Construct bicyclic peptides with dual-targeting ability through fusion of cyclic peptide ligand targeting overexpressed receptors in tumor cells. This project should provide a new chemical tool and approach to stabilize peptides for enhanced tumor targeting, reduced non-specific toxicity, and increased therapeutic index.

多肽可调控重要癌症相关蛋白-蛋白相互作用，因而受到广泛关注。但线性多肽存在稳定性差、细胞穿透性差、细胞活性差等问题，以订书肽为代表的环状稳定多肽克服了上述问题，被认为是下一代治疗性分子。然而订书肽缺乏肿瘤靶向性，并且由于引入疏水性侧链而表现出较强的非特异性毒性，由此引起的脱靶问题降低了临床转化的安全性。本项目拟通过构建新型低脱靶双环稳定多肽体系，提高多肽稳定性，降低其非特异性毒性，并通过双环结构引入靶向肿瘤细胞表面受体的环状多肽配体，在同一骨架中实现提高多肽靶向性、稳定性、细胞穿透能力及细胞活性的目的。本项目的研究内容为：1.利用巯基-炔点击化学的双加成特点，构建低脱靶烷基双硫醚侧链双环稳定多肽体系；2.通过嵌合靶向肿瘤细胞表面受体的环状多肽配体，构建具有双重靶向能力的双环稳定多肽。本项目有望为提高多肽靶向性、降低非特异性毒性、提高疗效提供一种新的工具和手段。

以订书肽(Stapled Peptides)为代表的稳定多肽由于具有更强的稳定性和细胞穿透能力得到了广泛的关注，并被认为是下一代治疗性分子。项目负责人围绕如何提高稳定多肽肿瘤靶向能力和穿透能力这一主线进行研究，主要成果包括：1)基于巯基-炔点击化学双加成特点，发展了一种构建新型含烷基双硫醚侧链的双环稳定多肽方法，实现了利用双环骨架稳定多肽α-螺旋构象并增强其肿瘤靶向能力，为提高稳定多肽的肿瘤靶向性及疗效提供一种通用的手段；2)为提高稳定多肽靶向能力，克服正电性多肽在血液循环中容易被清除的问题，构建了可响应肿瘤微环境pH的可激活稳定多肽纳米药物，利用肿瘤EPR效应选择性地在肿瘤部位富集，增强了肿瘤靶向治疗效果；3)设计并合成了具有疏水性侧链的稳定化穿膜肽，研究了该类稳定化穿膜肽的细胞穿透能力，并探索了稳定化穿膜肽的跨细胞穿透能力，为后续利用该类分子促进药物递送提供了研究基础。本项目研究工作为提高靶向分子的多样性，优化稳定多肽性质，拓展稳定多肽的应用提供了研究基础并具有潜在的应用价值。