Laboratory of Cell Protection Mechanisms, Institute of Cytology of Russian Academy of Sciences, Tikhoretsky ave, 4, St. Petersburg, 194094, Russia.
A. N. Belozersky Research Institute of Physico-Chemical Biology, Moscow State University, Leninskye gory, house 1, building 40, Moscow, 119992, Russia.
Cell Death Dis. 2018 Jan 18;9(2):41. doi: 10.1038/s41419-017-0160-y.
Hsp70 chaperone controls proteostasis and anti-stress responses in rapidly renewing cancer cells, making it an important target for therapeutic compounds. To date several Hsp70 inhibitors are presented with remarkable anticancer activity, however their clinical application is limited by the high toxicity towards normal cells. This study aimed to develop assays to search for the substances that reduce the chaperone activity of Hsp70 and diminish its protective function in cancer cells. On our mind the resulting compounds alone should be safe and function in combination with drugs widely employed in oncology. We constructed systems for the analysis of substrate-binding and refolding activity of Hsp70 and to validate the assays screened the substances representing most diverse groups of chemicals of InterBioScreen library. One of the inhibitors was AEAC, an N-amino-ethylamino derivative of colchicine, which toxicity was two-orders lower than that of parent compound. In contrast to colchicine, AEAC inhibited substrate-binding and refolding functions of Hsp70 chaperones. The results of a drug affinity responsive target stability assay, microscale thermophoresis and molecular docking show that AEAC binds Hsp70 with nanomolar affinity. AEAC was found to penetrate C6 rat glioblastoma and B16 mouse melanoma cells and reduce there the function of the Hsp70-mediated refolding system. Although the cytotoxic and growth inhibitory activities of AEAC were minimal, the compound was shown to increase the antitumor efficiency of doxorubicin in tumor cells of both types. When the tumors were grown in animals, AEAC administration in combination with doxorubicin exerted maximal therapeutic effect prolonging animal survival by 10-15 days and reducing tumor growth rate by 60%. To our knowledge, this is the first time that this approach to the high-throughput analysis of chaperone inhibitors has been applied, and it can be useful in the search for drug combinations that are effective in the treatment of highly resistant tumors.
热休克蛋白 70 伴侣控制快速更新的癌细胞中的蛋白质稳态和抗应激反应，使其成为治疗化合物的重要靶标。迄今为止，已经提出了几种 HSP70 抑制剂，具有显著的抗癌活性，但其临床应用受到对正常细胞高毒性的限制。本研究旨在开发用于寻找降低 HSP70 伴侣活性并减弱其在癌细胞中保护功能的物质的测定法。我们考虑的是，单独使用这些化合物应该是安全的，并与在肿瘤学中广泛使用的药物联合使用。我们构建了用于分析 HSP70 底物结合和重折叠活性的系统，并筛选了代表 InterBioScreen 文库中最广泛的化学物质组的物质来验证测定法。抑制剂之一是 AEAC，它是秋水仙碱的 N-氨基乙氨基衍生物，其毒性比母体化合物低两个数量级。与秋水仙碱不同，AEAC 抑制 HSP70 伴侣的底物结合和重折叠功能。药物亲和反应靶标稳定性测定、微量热泳动和分子对接的结果表明，AEAC 以纳摩尔亲和力与 HSP70 结合。发现 AEAC 穿透 C6 大鼠神经胶质瘤和 B16 小鼠黑色素瘤细胞，并降低其 HSP70 介导的重折叠系统的功能。尽管 AEAC 的细胞毒性和生长抑制活性最小，但该化合物被证明可以增加两种类型肿瘤细胞中阿霉素的抗肿瘤效率。当在动物中生长肿瘤时，AEAC 联合阿霉素给药发挥最大的治疗效果，将动物的存活时间延长 10-15 天，并将肿瘤生长速度降低 60%。据我们所知，这是首次应用这种高内涵分析伴侣抑制剂的方法，它可用于寻找对高度耐药肿瘤有效的药物组合。
