“死亡蛋白”-Bax的高分子模拟物的构建和肿瘤靶向递送

A polymeric mimic of active Bax is proposed to be developed for the targeted drug delivery of therapeutic peptides to tumor cells with high efficiency. With biocompatible material, i.e. poly-HPMA, as the matrix, and the cyclic peptide cRGDyK as the tumor cell targeting group, Bax-BH3 peptides are going to be used as active sites of the polymeric mimics. The polymer, which possesses one carboxyl group and multiple azide groups, will be synthesized by living polymerization and be covalently modified on its carboxyl group by cyclic peptide cRGDyK. The click chemistry method will be applied under the gentle condition to anchor peptides to polymeric carrier through their alkane group on the C- terminal of peptides. The ability for targeting tumor cell and inducing apoptosis will be determined with cultured cells and mouse models, respectively. In the meantime, the toxicity of these polymeric mimics will be evaluated and the molecular mechanism will be investigated. By using biocompatible materials which are also easily enriched and absorbed by tumor cells, the major significance of this proposal is that this method takes all four aspects of cancer therapeutic peptides into account, including their biostability, activity, membrane permeability and cancer cell-specificity, to functionally perform as active Bax proteins leading to cell apoptosis. Accomplishment of this proposal will provide us a valuable choice for cancer intervention and a new approach to rationally designing biomimetic therapeutics.

本研究旨在用带有功能多肽的有机高分子来模拟“死亡蛋白”即细胞凋亡活性蛋白Bax，从而实现肿瘤细胞的靶向递送和治疗。此高分子模拟物用生物相容性材料pHPMA模拟bax 蛋白中的骨架肽段，并带有部分正电性和荧光基团，以多个Bax-BH3多肽为活性部位，以cRGDyK环肽为肿瘤细胞靶向部位。首先用活性聚合的方法获得具有单一羧基和多个叠氮基团的有机高分子，然后使cRGDyK与高分子的羧基以酰胺键交联，最后采用点击化学的方法在温和条件下让炔基标记的多肽与高分子共价交联。将分别利用细胞和模式动物实验来检测高分子模拟物的肿瘤细胞靶向和诱导细胞凋亡的功能并对其毒性和凋亡分子机制进行研究。本项目主要特色在于用具生物相容性且容易被肿瘤细胞识别并吸收的有机高分子材料来模拟细胞凋亡的关键蛋白Bax以激活相应细胞的凋亡，此法兼顾了抗肿瘤多肽药物的稳定性、活性、细胞膜通透性和靶向性，将为肿瘤治疗提供有价值的新途径。

本研究旨在用带有功能多肽的有机高分子来模拟“死亡蛋白”即细胞凋亡活性蛋白Bax，从而实现肿瘤细胞的靶向递送和治疗。BH3域可以激活Bax并使其低聚核化以诱导细胞凋亡。因此我们选择BH3域内的多肽来模拟BAX活性部分。PHPMA是一种高度亲水的聚合物，具有较好的生物相容性，不易引起免疫反应，由于羟基的存在，已被设计为药物定点递送的载体。这些特性使得pHPMA适合用于模拟bax 蛋白中的骨架肽段。罗丹明B具有荧光性强，不易猝灭的优点，因此选择它作为高分子模拟物的荧光基团。此高分子模拟物用生物相容性材料pHPMA模拟bax 蛋白中的骨架肽段，并带有部分正电性和荧光基团，以多个Bax-BH3多肽为活性部位，以cRGDyK环肽为肿瘤细胞靶向部位。首先用活性聚合的方法获得具有单一羧基和多个叠氮基团的有机高分子，然后使cRGDyK与高分子的羧基以酰胺键交联，最后采用点击化学的方法在温和条件下让炔基标记的多肽与高分子共价交联，所得纳米载体可用于抗肿瘤药物的递送。利用细胞和模式动物实验来检测高分子模拟物的肿瘤细胞靶向和诱导细胞凋亡的功能并对其毒性和凋亡分子机制进行研究。本项目主要特色在于用具生物相容性且容易被肿瘤细胞识别并吸收的有机高分子材料来模拟细胞凋亡的关键蛋白Bax以激活相应细胞的凋亡，并利用肿瘤部位的EPR效应被动靶向到肿瘤部位，pHPMA聚合物载体中含有荧光分子Rob，通过其荧光特性可以更方便的进行药物示踪和成像，在诊断疾病的同时对疾病进行治疗，实现疾病的诊疗一体化和疾病检测的可视化。此法兼顾了抗肿瘤多肽药物的稳定性、活性、细胞膜通透性和靶向性，将为肿瘤治疗提供有价值的新途径。