Overcoming mutation-based resistance to antiandrogens with rational drug design.
Overcoming mutation-based resistance to antiandrogens with rational drug design.
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DOI：
10.7554/elife.00499
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发表时间：
2013-04-09
期刊：
影响因子：
7.7
通讯作者：
Sawyers CL
中科院分区：
文献类型：
--
作者：
Balbas MD;Evans MJ;Hosfield DJ;Wongvipat J;Arora VK;Watson PA;Chen Y;Greene GL;Shen Y;Sawyers CL
第二代抗雄激素Enzalutamide最近获批用于去势抵抗性前列腺癌患者。尽管取得了成功，但反应的持续时间往往有限。对于先前的抗雄激素，抗性的一种机制是雄激素受体（AR）的突变。为了前瞻性地鉴定可能赋予Enzalutamide耐药性的AR突变，我们进行了基于突变的诱变筛选，并鉴定了一种新突变F876 L，其将Enzalutamide转化为AR激动剂。AR F876 L的异位表达挽救了Enzalutamide处理的生长抑制。对抗雄激素-AR复合物进行的分子动力学模拟表明，F876 L取代通过重新定位共激活因子招募螺旋12来增强拮抗作用的机制。然后，该模型提供了集中化学筛选的基本原理，该化学筛选基于现有的抗雄激素支架，鉴定了三种有效拮抗AR F876 L（和AR WT）以抑制对Enzalutamide耐药的前列腺癌细胞生长的新型化合物。http://dx.doi.org/10.7554/eLife.00499.001前列腺癌是男性最常见的癌症，也是第二大致命癌症。前列腺癌的所有阶段都依赖于男性性激素，也称为雄激素，因为这些激素结合并激活雄激素受体。一类被称为“抗雄激素”的药物可以有效地治疗前列腺癌，因为它们与雄激素受体结合而不激活它们，从而阻止雄激素结合。然而，即使是高效抗雄激素药物（如Enzalutamide）在许多患者中的疗效也很短，了解导致耐药的生物学机制是转化型前列腺癌研究的主要目标之一。抗雄激素药物可通过雄激素受体的突变导致受体被激活而不是抑制而产生耐药性。然而，Enzalutamide还没有发现这样的突变，研究人员热衷于了解它们是否存在，如果存在，则产生克服它们的前列腺癌新药。为了识别可能导致耐药的突变，Balbas等人设计了一种新的人前列腺癌细胞筛选方法，并显示具有特定突变（称为F876 L）的雄激素受体可被enzalutamide激活。更全面的生物学研究表明，携带突变的前列腺癌细胞在接受药物治疗时继续生长。Balbas et al.还表明，这种突变可以在长期接受enzalutamide治疗的人前列腺癌细胞中自发发生。Balbas et al.推断该突变可能改变了Enzalutamide与雄激素受体结合的方式，并使用受体和药物形成的复合物的计算机引导结构建模来研究这可能如何发生。这些研究表明，含有F876 L突变的雄激素受体区域与药物直接接触，并为抑制作用的丧失提供了结构解释。由于这些研究显示了Enzalutamide可能如何与雄激素受体结合，因此还提出了对Enzalutamide进行化学修饰以恢复其对突变型受体的抑制活性的方法。Balbas等人随后设计并合成了一系列新化合物，建模数据表明这些化合物可以作为突变受体的抑制剂。这些化合物中的几种抑制雄激素受体的突变体和野生型形式的活性，并抑制Enzalutamide耐药和非耐药前列腺癌细胞的生长。Balbas等人的工作概述了发现癌症基因中临床相关突变的一般筛选策略，并显示了计算机技术如何在缺乏蛋白质-药物复合物晶体结构的情况下加速药物发现。它还强调如何理解药物结合其靶点的方式可以刺激改进候选药物的合理设计。DOI：http://dx.doi.org/10.7554/eLife.00499.002网站
The second-generation antiandrogen enzalutamide was recently approved for patients with castration-resistant prostate cancer. Despite its success, the duration of response is often limited. For previous antiandrogens, one mechanism of resistance is mutation of the androgen receptor (AR). To prospectively identify AR mutations that might confer resistance to enzalutamide, we performed a reporter-based mutagenesis screen and identified a novel mutation, F876L, which converted enzalutamide into an AR agonist. Ectopic expression of AR F876L rescued the growth inhibition of enzalutamide treatment. Molecular dynamics simulations performed on antiandrogen–AR complexes suggested a mechanism by which the F876L substitution alleviates antagonism through repositioning of the coactivator recruiting helix 12. This model then provided the rationale for a focused chemical screen which, based on existing antiandrogen scaffolds, identified three novel compounds that effectively antagonized AR F876L (and AR WT) to suppress the growth of prostate cancer cells resistant to enzalutamide. DOI: http://dx.doi.org/10.7554/eLife.00499.001 Prostate cancer is the most commonly diagnosed cancer in men, and the second most lethal. All stages of prostate cancer depend upon male sex hormones, also known as androgens, to grow because these hormones bind and activate androgen receptors. A class of drugs termed ‘antiandrogens’ can effectively treat prostate cancer because they bind to androgen receptors without activating them, thereby preventing androgens from binding. However, the efficacy of even highly potent antiandrogen drugs, such as enzalutamide is short-lived in many patients, and understanding the biological mechanisms that cause drug resistance is one of the major objectives in translational prostate cancer research. Resistance can arise through mutations of the androgen receptor that result in the receptor being activated, rather than inhibited, by antiandrogen drugs. However, no such mutations are known yet for enzalutamide, and researchers are keen to understand whether they exist and, if so, to generate new drugs for prostate cancer that overcome them. To identify mutations that may lead to resistance, Balbas et al. designed a new screening method in human prostate cancer cells and showed that androgen receptors with a specific mutation (called F876L) can be activated by enzalutamide. More comprehensive biological studies showed that prostate cancer cells harboring the mutation continued to grow when treated with the drug. Balbas et al. also showed that this mutation can arise spontaneously in human prostate cancer cells treated long term with enzalutamide. Balbas et al. reasoned that the mutation likely altered the way enzalutamide binds to the androgen receptor, and used computer-guided structural modeling of the complex formed by the receptor and the drug to investigate how this might occur. These studies indicated that the region of the androgen receptor containing the F876L mutation comes into direct contact with the drug, and provided a structural explanation for the loss of inhibition. Because these studies showed how enzalutamide might bind to the androgen receptor, they also suggested ways in which enzalutamide could be chemically modified to restore its inhibitory activity against the mutant receptor. Balbas et al. then designed and synthesized a set of novel compounds, which the modeling data suggested could act as inhibitors of the mutant receptor. Several of these compounds inhibited the activity of both mutant and wild-type forms of the androgen receptor, and suppressed the growth of both enzalutamide-resistant and nonresistant prostate cancer cells. The work of Balbas et al. outlines a general screening strategy for the discovery of clinically relevant mutations in cancer genes, and shows how in silico technologies can accelerate drug discovery in the absence of a crystal structure of a protein–drug complex. It also emphasizes how understanding the manner in which a drug binds its target can stimulate rational design of improved drug candidates. DOI: http://dx.doi.org/10.7554/eLife.00499.002