Synthesis of 19-substituted geldanamycins with altered conformations and their binding to heat shock protein Hsp90
作者:Russell R. A. Kitson、Chuan-Hsin Chang、Rui Xiong、Huw E. L. Williams、Adrienne L. Davis、William Lewis、Donna L. Dehn、David Siegel、S. Mark Roe、Chrisostomos Prodromou、David Ross、Christopher J. Moody
DOI:10.1038/nchem.1596
日期:2013.4
The benzoquinone ansamycin geldanamycin and its derivatives are inhibitors of heat shock protein Hsp90, an emerging target for novel therapeutic agents both in cancer and in neurodegeneration. However, the toxicity of these compounds to normal cells has been ascribed to reaction with thiol nucleophiles at the quinone 19-position. We reasoned that blocking this position would ameliorate toxicity, and that it might also enforce a favourable conformational switch of the trans-amide group into the cis-form required for protein binding. Here, we report an efficient synthesis of such 19-substituted compounds and realization of our hypotheses. Protein crystallography established that the new compounds bind to Hsp90 with, as expected, a cis-amide conformation. Studies on Hsp90 inhibition in cells demonstrated the molecular signature of Hsp90 inhibitors: decreases in client proteins with compensatory increases in other heat shock proteins in both human breast cancer and dopaminergic neural cells, demonstrating their potential for use in the therapy of cancer or neurodegenerative diseases. The heat shock protein Hsp90 is a potential target for cancer and neurodegeneration drugs. Here, the introduction of a substituent into the 19-position of the naturally occurring inhibitor geldanamycin by chemical synthesis is shown to ameliorate toxicity, and also cause a favourable conformational switch that is required for protein binding.
苯醌类的安赛蜜(geldanamycin)及其衍生物是热休克蛋白Hsp90的抑制剂,Hsp90是癌症和神经退行性疾病中新兴的治疗靶点。然而,这些化合物对正常细胞的毒性被归因于它们与醇类亲核试剂在醌的19位点反应。我们推测,封闭该位置将减轻毒性,同时也可能促使反式酰胺基团转变为蛋白质结合所需的顺式结构。在这里,我们报告了这种19取代化合物的高效合成及我们假设的实现。蛋白质晶体学表明,新化合物与Hsp90结合时,确实呈现出顺式酰胺构象。对细胞中Hsp90抑制的研究展示了Hsp90抑制剂的分子特征:在人体乳腺癌和多巴胺能神经细胞中,客户蛋白减少,其他热休克蛋白相应增加,显示出它们在癌症或神经退行性疾病治疗中的潜力。热休克蛋白Hsp90是癌症和神经退行性药物的潜在靶点。在这里,化学合成将在天然抑制剂安赛蜜的19位引入取代基,显示出减轻毒性,并促使所需的蛋白质结合顺式构象的有利转变。