抗耐药肿瘤特异性细胞穿膜肽-蛋白酶体抑制剂结合物的设计、合成及生物学评价

Covalent peptidyl proteasome inhibitors were employed as anti-multiple myeloma (MM) drugs in clinical. However, the severe side effects and drug resistance were ubiquitous. Therefore, it’s of great significance to develop anti-MM drugs with metabolic stability and efficient transportation profiles to MM cells to solve the abovementioned problems. In this project, previously developed non-covalent peptidyl proteasome inhibitor ZJK-G35 with potent in vitro and ex vivo activities and low toxicity was employed as the lead compound. Based on the metabolic and docking studies of ZJK-G35, new analogues were designed with retained hydrogen bonding interactions and blocked metabolic sites. Additionally, conjugates of tumor specific cell penetrating peptides (tsCPPs) and proteasome inhibitors with poor in vivo activities were combined with a cleavable linker. With the assistance of tsCPPs, small molecular drugs could be rapidly transported into tumor cells instead of normal cells. This technique could avoid the drug metabolism in the process of blood circulation, as well as reduce the toxicity and overcome the drug resistance caused by the deterioration of cell membrane permeability and drug efflux.

作为多发性骨髓瘤的治疗药物，短肽共价结合类蛋白酶体抑制剂普遍存在毒副作用大、易产生耐药等问题，故研发代谢稳定且可高效转运至骨髓瘤细胞的短肽非共价类蛋白酶体抑制剂对解决上述问题具重大意义。本项目以前期研究发现的体外活性优良且毒性较小的短肽非共价结合类蛋白酶体抑制剂ZJK-G35为先导物，在分析其代谢途径、靶标结合模式的基础上，通过封闭代谢位点对其进行结构改造，期望获得活性相当、代谢稳定性显著改善的目标分子。此外，针对部分体内活性欠佳的化合物，我们采用在细胞内可裂解的Linker将其与肿瘤特异性细胞穿膜肽（tsCPPs）共价连接，利用后者的肿瘤组织靶向性，将化合物高效转运至肿瘤细胞内，从而减少其进入正常细胞以及在体循环中的代谢，在发挥抗肿瘤效果的同时，降低药物毒性、克服细胞膜通透性不佳及药物外排引起的耐药。

多发性骨髓瘤是一类严重威胁人类健康的恶性肿瘤，而蛋白酶体抑制剂是治疗多发性骨髓瘤的一类重要药物。目前获批上市的三个蛋白酶体抑制剂均属于短肽共价类化合物，均具有较大的毒副作用。前期工作中，我们发现了一个具有良好体外活性，但体内抗肿瘤活性不足的非共价蛋白酶体抑制剂。为了提高其体内抗肿瘤活性，本研究从两个途径着手：1）采用基于代谢的药物设计策略，结合分子对接，设计并合成了32个羧基末端大基团取代或氨基末端N-烷基化的新型拟肽类化合物。部分目标化合物具有良好的蛋白酶体抑制活性及肿瘤细胞增殖抑制活性，还具有更好的血稳定性及体内蛋白酶体抑制活性，该研究显示了该设计策略对于提高肽类化合物体内活性的可靠性。2）细胞穿膜肽可作为药物载体提高药物的体内活性，但多数穿膜肽缺乏对肿瘤细胞的选择性。本研究对已报道穿膜肽D-R8进行结构修饰，得到8个新的肽类化合物，对其进行肿瘤细胞和正常细胞的细胞增殖抑制活性评价、细胞摄取评价后，优选具有肿瘤特异性的穿膜肽分子与优选的小分子蛋白酶体抑制剂连接，得到了一个复合分子。该分子仍具有较好的蛋白酶体抑制活性。该研究为提高药物体内抗肿瘤活性提供了借鉴与思路。