分子靶向与电荷屏蔽协同修饰的新型低毒抗菌肽及其抗肿瘤应用

Development of anticancer drugs with efficiency and low toxicity remains a considerable challenge. Based on the unique mechanism of membrane damage, antimicrobial peptides are gaining more attention. However, the toxic and side effect hinders the clinical application of antimicrobial peptides. To improve the antitumor application of antimicrobial peptides, in this project, we designed a novel molecular targeting and charge shielding strategy that the lysines side chain aminos of antimicrobial peptide Melittin were conjugated with folate via cleavable linker.. The decreased toxicity and increased selectivity are by masking the Lys positive charges with folate. After the folate targeted Melittin conjugate entering tumor cells, Melittin is released from the conjugate and then recover its membrane disruption activity. The released Melittin can induces cell apoptosis by disrupting mitochondria or facilitate the endosomal escape of macromolecules by ruptureing the endosomal membrane. This strategy is simple and feasible, therefore it also can be used to modify other antimicrobial peptides to develop efficient antitumor drugs or gene vectors. Additionly, this strategy is contributed to the useful exploration of clinical applications of antimicrobial peptide in the antitumor field.

如何发展高效低毒的抗肿瘤药物仍然面临着巨大的挑战。抗菌肽因其独特的作用机制而受到广泛关注，但毒副作用却限制了它的临床抗肿瘤应用。本项目通过发展一类简单、新型的分子靶向和电荷屏蔽协同的修饰策略，以提高抗菌肽的临床应用能力。这种策略将叶酸分子通过可释放的连接子与抗菌肽Melittin的赖氨酸侧链氨基相连，既可以通过叶酸分子增加Melittin的选择性，又可以通过屏蔽赖氨酸侧链所带正电荷而降低Melittin的毒性。另外通过对连接子的筛选和研究，使药物进入肿瘤细胞后更容易将Melittin等抗菌肽释放出来，恢复其破膜活性，进而作用于线粒体诱导细胞凋亡，或者负载基因治疗药物等大分子使其更容易作用于靶位点。这种修饰策略简单易行，因此也可扩展到其它高活性抗菌肽的修饰与应用上，用于发展高效的抗肿瘤药物或肿瘤基因治疗的药物载体，为抗菌肽在抗肿瘤领域的应用进行有益的探索。

传统抗肿瘤药物毒副作用强、易引起多药耐药而影响临床疗效，抗菌肽因其选择性高、作用机制新而受到广泛关注，但天然抗菌肽本身所带的多价正电荷使其仍然具有一定的毒副作用。本项目以天然抗菌肽Melittin等为模板，通过优化和筛选，将叶酸分子通过不同方式偶联到抗菌肽序列中，并对抗菌肽赖氨酸侧链电荷进行屏蔽。抗肿瘤活性和选择性研究表明，叶酸的引入可以提高抗菌肽的靶向性和肿瘤细胞选择性，同时电荷的屏蔽可以降低抗菌肽的毒副作用，表明这种分子靶向与电荷屏蔽协同修饰的设计思路具有可行性，为新型靶向抗肿瘤药物的发展提供了理论支持。同时，我们利用电荷屏蔽和酸激活策略降低了抗菌肽的毒性，并利用抗菌肽自身的靶向性偶联化疗药物提高药效。为抗菌肽在抗肿瘤领域的应用，特别是发展高效的抗肿瘤药物或药物载体方面进行了有益的探索。此外对抗菌肽类似物的抗菌活性和作用机制进行了研究，为新型抗生素的发展提供了研究基础。项目执行以来，已在Mol. Pharm.等重要国际期刊发表高质量SCI论文7篇，获国家发明专利授权1项，并通过项目的实施培养了硕士研究生4名。