Broadened ligand responsiveness of androgen receptor mutants obtained by random amino acid substitution of H874 and mutation hot spot T877 in prostate cancer
Broadened ligand responsiveness of androgen receptor mutants obtained by random amino acid substitution of H874 and mutation hot spot T877 in prostate cancer
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DOI：
10.1002/ijc.10495
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发表时间：
2002-07-20
影响因子：
6.4
通讯作者：
Trapman, J
中科院分区：
文献类型：
--
作者：
Steketee, K;Timmerman, L;Trapman, J
在内分泌治疗抗性前列腺癌的子集中，已经检测到氨基酸取代H874 Y、T877 A和T877 S，其拓宽了雄激素受体（AR）的配体结合结构域（LBD）的配体特异性。为了增加我们对前列腺癌中这些特定位置的氨基酸取代的作用的了解，对密码子874和877进行随机诱变。在酵母读出系统中筛选AR突变体对5 α-二氢睾酮、孕酮和脱氢表雄酮的反应性。在位置874处，仅组氨酸至酪氨酸取代可扩大AR配体特异性。在位置877处，发现4个配体特异性加宽置换：T877 A、T877 S、T877 C和T877 G。后2种在前列腺癌中未发现。在哺乳动物（Hep 3B）细胞中测试AR突变体对13种不同配体的响应性。所有突变体均显示出各自的配体特异性谱。重要的是，AR（H874 Y）和AR（T877 A）可以被皮质醇激活。根据AR LBD的三维结构，T877直接与雄激素的17 β-羟基相互作用。在位置877处鉴定的所有氨基酸取代具有比野生型受体中的苏氨酸更小的侧链，这表明配体结合口袋中增加的空间在加宽的配体特异性中是重要的。由于H874不直接与配体相互作用，因此预期其被酪氨酸取代会间接改变配体结合口袋构象。对于T877 C和T877 G置换，需要2点突变，而对于H874 Y、T877 A和T877 S置换，仅1点突变就足够了。这很可能解释了后3种在前列腺癌中被发现。(C)2002 Wiley-Liss，Inc.
In a subset of endocrine therapy-resistant prostate cancers, amino acid substitutions H874Y, T877A and T877S, which broaden ligand specificity of the ligand binding domain (LBD) of the androgen receptor (AR), have been detected. To increase our knowledge of the role of amino acid substitutions at these specific positions in prostate cancer, codons 874 and 877 were subjected to random mutagenesis. AR mutants were screened in a yeast readout system for responsiveness to 5alpha-dihydrotestosterone, progesterone and dehydroepiandrosterone. At position 874, only the histidine to tyrosine substitution could broaden AR ligand specificity. At position 877, 4 ligand specificity broadening substitutions were found: T877A, T877S, T877C and T877G. The latter 2 were not found in prostate cancer. The AR mutants were tested in mammalian (Hep3B) cells for responsiveness to 13 different ligands. All mutants displayed their own ligand specificity spectrum. Importantly, AR(H874Y) and AR(T877A) could be activated by cortisol. According to the 3-dimensional structure of the AR LBD, T877 interacts directly with the 17beta-hydroxyl group of androgens. All amino acid substitutions identified at position 877 had smaller side chains than the threonine in the wild-type receptor, indicating that increased space in the ligand binding pocket is important in broadened ligand specificity. Because H874 does not interact directly with the ligand, its substitution by a tyrosine is expected to change the ligand binding pocket conformation indirectly. For T877C and T877G substitutions, 2-point mutations are required, and for H874Y, T877A and T877S substitutions, only a 1-point mutation is sufficient. This most likely explains that the latter 3 have been found in prostate cancer. (C) 2002 Wiley-Liss, Inc.