Development Of Drugs Acting At Adenosine Receptors

作用于腺苷受体的药物的开发

• 批准号: 8349717
• 负责人: Kenneth Alan Jacobson
• 金额: $ 36.14万
• 依托单位: NATIONAL INSTITUTE OF DIABETES AND DIGESTIVE AND KIDNEY DISEASES
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/8349717
• 关键词: Adenine; Adenosine; Adenosine A3 Receptor; Affect; Affinity; Agonist; Anti-Inflammatory Agents; Anti-inflammatory; Autoimmune Process; Binding; Binding Sites; Biochemical; Biological Assay; Brain; California; Cardiac Myocytes; Cardiovascular Diseases; Cell Surface Proteins; Cells; Chronic Obstructive Airway Disease; Clinical Treatment; Clinical Trials; Collaborations; Cooperative Research and Development Agreement; Dependence; Development; Diagnostic; Disease; Endocrine; Enhancers; Eye diseases; Family; Fluorescence Polarization; G-Protein-Coupled Receptors; Gerbils; Glaucoma; Goals; Heart; Hepatitis C virus; Homology Modeling; Human; Immune system; Inflammatory; Ischemia; Korea; Libraries; Ligands; Location; Malignant Neoplasms; Malignant neoplasm of liver; Methodology; Modeling; Modification; Molecular Conformation; Molecular Models; Molecular Structure; Movement; Mus; Muscle Cells; Mutagenesis; Myocardial Ischemia; Neuraxis; Neurodegenerative Disorders; Nucleosides; Nucleotides; Opsin; Patients; Pennsylvania; Peripheral; Pharmaceutical Preparations; Phase; Phase II Clinical Trials; Physiologic Intraocular Pressure; Physiological; Positioning Attribute; Process; Property; Psoriasis; Purinergic P1 Receptors; Radioactivity; Rattus; Receptor Activation; Relative (related person); Reporting; Research; Resolution; Rheumatoid Arthritis; Rhodopsin; Ribose; Role; Rotation; Sampling; San Francisco; Screening procedure; Sequence Analysis; Sequence Homology; Series; Signal Transduction; Skeletal Muscle; Structure; Structure-Activity Relationship; System; Therapeutic; Therapeutic Agents; Therapeutic Clinical Trial; Tissues; Viral Load result; Work; analog; base; clinical efficacy; design; drug discovery; extracellular; eye dryness; interest; molecular modeling; mouse model; novel; receptor; receptor binding; small molecule

The extracellular adenosine receptors have a modulatory role in the nervous, circulatory, endocrine and immunological systems. The prospect of harnessing these effects specifically for therapeutic purposes is attractive. We have recently synthesized highly selective A3 adenosine receptor agonists, antagonists, allosteric modulators. A3 agonists are under development for treating cancer, rheumatoid arthritis, and other diseases. Allosteric enhancers promise to be more specific in their action in an affected tissue, than a classical agonist, which can act at all locations of the receptor in the body. Imidazoquinoline and pyridinylisoquinoline derivatives were found to enhance the actions of agonists of the A3 receptor, and thus may prove to be suitable leads for the development of therapeutic agents based on this concept. We have identified two new classes of allosteric modulators of the A3 receptor and are currently exploring the structure activity relationship (SAR). The potential of A3 agonist therapy is of great interest. We are collaborating with Dr. Bruce Liang and Dr. Asher Shainberg on various aspects of the use of adenosine receptor agonists in protection of the heart. We have designed a mixed agonist of A1 and A3 subtypes, both of which are protective in the heart. A mixed A1/A3 agonist is protective in a model of ischemia in skeletal muscle. The adenosine A3 agonist IB-MECA is currently in clinical trials for use in autoimmune inflammatory diseases and cancer conducted by our CRADA partner Can-Fite Biopharma. This compound has already shown clinical efficacy in Phase 2 trials for treatment of rheumatoid arthritis, psoriasis, and dry eye disease. IB-MECA (CF-101) has just entered Phase 2/3 clinical trials for psoriasis. The 2-chloro analogue is currently in clinical trials for liver cancer, and it was shown to reduce viral load in several patients that are infected with hepatitis C virus. Other more selective A3 agonists from our lab, such as the conformationally constrained MRS3558, are of interest for their protective properties. One of the issues in the development of adenosine receptor ligands is the species dependence. Some compounds that are very potent at a given human adenosine receptor are weak in rat tissue. We have developed adenosine agonists and antagonists that work generally across species. The key to A3 receptor ligands that are potent and selective across species is the use of the nucleoside structure as the starting point in the design process. Nucleosides tend to bind to that receptor subtype with greater consistency across species than nonpurine heterocycles. Adenosine A3 antagonists may be useful for the treatment of glaucoma. Early efforts to identify antagonists of the A3 receptor in our library involved screening of chemically diverse libraries. One of the limitations of this approach is that the antagonists often bind well only at the human, but not murine A3 receptors. We are currently developing other novel A3 antagonists based on nucleotide structures, that have proven to be generally applicable across species. We are currently studying systematically the SAR of adenosine derivatives that affect efficacy as A3 adenosine receptor agonists. Surprisingly, a commonly used A1-selective agonist, cyclopentyladenosine, was found to act as a pure antagonist at the A3 subtype. Other nucleosides may be chemically modified, especially on the ribose moiety, to have reduced efficacy at the A3 receptor. Some of these analogues derived from highly potent A3 agonists, such as 5'-truncated nucleosides, were found to be A3 antagonists. Several novel nucleoside-based antagonists of the A3 receptor, including a rigid spirolactam derivative MRS1292 and a truncated 4'-thioadenosine derivative (collaboration with Prof. Lak Shin Jeong, EHWA Univ., Seoul Korea) were found to lower intraocular pressure a mouse model of glaucoma (demonstrated by Prof. Mort Civan, Univ. of Pennsylvania). We are using mutagenesis to study the determinants of recognition of adenosine within the binding site of the A2A and A3 receptors, and proposing conformational factors involved in receptor activation. Since the four subtypes of adenosine receptors have been cloned it has been possible to conduct molecular modeling of the receptor protein, based on sequence analyses and homology modeling using the high resolution rhodopsin structure as template. We intend to use such a modeling approach for the design of more selective adenosine receptor agonists and antagonists. Recently this project has also focused on the effects of adenosine agonists and antagonists in the central nervous system and in the heart and on the possibility of therapeutics for treating neurodegenerative and cardiovascular diseases. An A3 agonist, administered chronically, proved to be highly cerebroprotective in an ischemic model in gerbils. A3 agonists cause morphological and biochemical changes in astroglial cells. Adenosine is released in large amounts during myocardial ischemia and is capable of activating both A1 or A3 receptors that occur on cardiac myocytes to exert a potent cardioprotective effect. We have shown that synthetic adenosine agonists,selective for either the A1 or A3 subtype, protect ischemic cardiac myocytes in culture and in the isolated perfused heart and thus might be beneficial to the survival of the ischemic heart. We recently succeeded in identifying new chemotypes for antagonists of the A2A receptor using structure-based drug discovery (collaboration with B. Shoichet, Univ. of California, San Francisco). We also introduced a fluorescence polarization assay for affinity at the same receptor, that avoids the use fo radioactivity in the drug discovery/screening process. Adenosine receptor agonists, including those selective for the A2A subtype, are in clinical trials for therapeutic and diagnostic applications. Known A2A receptor agonists, most of which contain large substituents at various positions, display anti-inflammatory and vasodilatory properties. We have discovered a means of reducing the size of the ribose moiety of 4-thioadenosine agonists by truncation that preserves the ability to potently activate the A2A receptor. The same modification in nucleosides that are selective for the A3 receptor was shown previously to convert agonists into antagonists at that subtype, but the present series, modified with an A2A receptor-favoring group at the 2 position of the adenine moiety, maintained the ability to fully activate this subtype. Thus, there is a major difference in the mode of activation between the two subtypes. The coexistence of A2A receptor agonism and A3 receptor antagonism in this series of sterically small nucleosides might prove to be beneficial therapeutically in a synergistic manner. Activation of G protein-coupled receptors (GPCRs) upon agonist binding is a critical step in the signaling cascade for this family of cell surface proteins. In collaboration with the Stevens group, we recently reported the crystal structure of the A2A adenosine receptor bound to an agonist UK-432097 (formerly in clinical trials for COPD) at 2.7 angstrom resolution. Relative to inactive, antagonist-bound A2A receptor, the agonist-bound structure displays an outward tilt and rotation of the cytoplasmic half of helix VI, a movement of helix V and an axial shift of helix III, resembling the changes associated with the active-state opsin structure. Additionally, a seesaw movement of helix VII and a shift of extracellular loop 3 are likely specific to A2A receptor and its ligand. Our results define the UK-432097 as a conformationally selective agonist capable of receptor stabilization in a specific active state, in contrast to other GPCR agonists that sample multiple conformational states.

细胞外腺苷受体在神经、循环、内分泌和免疫系统中具有调节作用。利用这些效应专门用于治疗目的的前景是有吸引力的。我们最近合成了高选择性A3腺苷受体激动剂、拮抗剂、变构调节剂。 A3 激动剂正在开发用于治疗癌症、类风湿性关节炎和其他疾病。与经典激动剂相比，变构增强剂有望在受影响的组织中发挥更特异的作用，后者可以作用于体内受体的所有位置。发现咪唑喹啉和吡啶基异喹啉衍生物可以增强A3受体激动剂的作用，因此可能被证明是基于这一概念开发治疗剂的合适先导。我们已经鉴定出两类新的 A3 受体变构调节剂，目前正在探索结构活性关系 (SAR)。 A3 激动剂疗法的潜力引起了人们极大的兴趣。 我们正在与 Bruce Liang 博士和 Asher Shainberg 博士就使用腺苷受体激动剂保护心脏的各个方面进行合作。 我们设计了 A1 和 A3 亚型的混合激动剂，这两种亚型都对心脏有保护作用。 混合 A1/A3 激动剂对骨骼肌缺血模型具有保护作用。 腺苷 A3 激动剂 IB-MECA 目前正在进行由我们的 CRADA 合作伙伴 Can-Fite Biopharma 进行的用于治疗自身免疫炎症性疾病和癌症的临床试验。 该化合物已在治疗类风湿关节炎、牛皮癣和干眼病的 2 期试验中显示出临床疗效。 IB-MECA (CF-101) 刚刚进入银屑病 2/3 期临床试验。 2-氯类似物目前正在进行肝癌的临床试验，并被证明可以减少几名感染丙型肝炎病毒的患者的病毒载量。我们实验室的其他更具选择性的 A3 激动剂，例如构象受限的 MRS3558，因其保护特性而令人感兴趣。 腺苷受体配体开发中的问题之一是物种依赖性。一些对特定人类腺苷受体非常有效的化合物在大鼠组织中却很弱。我们开发了普遍适用于不同物种的腺苷激动剂和拮抗剂。 A3 受体配体在物种间有效且具有选择性的关键是使用核苷结构作为设计过程的起点。 与非嘌呤杂环相比，核苷倾向于与该受体亚型结合，在物种间具有更高的一致性。 腺苷A3拮抗剂可用于治疗青光眼。在我们的文库中鉴定 A3 受体拮抗剂的早期工作涉及筛选化学多样化的文库。这种方法的局限性之一是拮抗剂通常仅与人类 A3 受体结合良好，而不能与小鼠 A3 受体结合。我们目前正在开发其他基于核苷酸结构的新型 A3 拮抗剂，这些拮抗剂已被证明普遍适用于跨物种。我们目前正在系统地研究影响 A3 腺苷受体激动剂功效的腺苷衍生物的 SAR。令人惊讶的是，人们发现常用的 A1 选择性激动剂环戊基腺苷可作为 A3 亚型的纯拮抗剂。其他核苷可能经过化学修饰，尤其是核糖部分，以降低对 A3 受体的功效。其中一些衍生自高效 A3 激动剂的类似物，例如 5'-截短核苷，被发现是 A3 拮抗剂。 几种新型核苷类 A3 受体拮抗剂，包括刚性螺内酰胺衍生物 MRS1292 和截短的 4'-硫腺苷衍生物（与韩国首尔 EHWA 大学 Lak Shin Jeong 教授合作）被发现可以降低小鼠模型的眼内压青光眼（由宾夕法尼亚大学 Mort Civan 教授演示）。 我们正在利用诱变研究 A2A 和 A3 受体结合位点内腺苷识别的决定因素，并提出参与受体激活的构象因素。由于腺苷受体的四种亚型已被克隆，因此可以基于序列分析和使用高分辨率视紫红质结构作为模板的同源性建模来进行受体蛋白的分子建模。我们打算使用这种建模方法来设计更具选择性的腺苷受体激动剂和拮抗剂。 最近，该项目还关注腺苷激动剂和拮抗剂在中枢神经系统和心脏中的作用，以及治疗神经退行性疾病和心血管疾病的可能性。事实证明，长期施用 A3 激动剂在沙鼠的缺血模型中具有高度的脑保护作用。 A3 激动剂引起星形胶质细胞的形态和生化变化。心肌缺血时腺苷会大量释放，能够激活心肌细胞上的 A1 或 A3 受体，发挥有效的心脏保护作用。我们已经证明，对 A1 或 A3 亚型具有选择性的合成腺苷激动剂可以保护培养物和离体灌注心脏中的缺血心肌细胞，因此可能有利于缺血心脏的存活。 我们最近利用基于结构的药物发现成功地鉴定了 A2A 受体拮抗剂的新化学型（与旧金山加利福尼亚大学 B. Shoichet 合作）。我们还引入了荧光偏振测定法来检测同一受体的亲和力，从而避免了在药物发现/筛选过程中使用放射性。 腺苷受体激动剂，包括对 A2A 亚型具有选择性的腺苷受体激动剂，正处于治疗和诊断应用的临床试验中。已知的 A2A 受体激动剂大多数在不同位置含有大量取代基，具有抗炎和血管舒张特性。我们发现了一种通过截短来减小 4-硫腺苷激动剂核糖部分大小的方法，从而保留有效激活 A2A 受体的能力。先前显示对 A3 受体具有选择性的核苷的相同修饰可将激动剂转化为该亚型的拮抗剂，但本系列在腺嘌呤部分的 2 位处用 A2A 受体有利基团进行修饰，保持了完全激活该亚型。因此，两种亚型之间的激活模式存在重大差异。这一系列空间小核苷中 A2A 受体激动剂和 A3 受体拮抗剂的共存可能被证明以协同方式在治疗上有益。 激动剂结合后 G 蛋白偶联受体 (GPCR) 的激活是该细胞表面蛋白家族信号级联中的关键步骤。 我们最近与 Stevens 小组合作，以 2.7 埃的分辨率报道了与激动剂 UK-432097（之前用于 COPD 临床试验）结合的 A2A 腺苷受体的晶体结构。相对于无活性的拮抗剂结合的 A2A 受体，激动剂结合的结构显示出螺旋 VI 的细胞质一半的向外倾斜和旋转、螺旋 V 的移动和螺旋 III 的轴向移位，类似于与活性相关的变化。状态视蛋白结构。此外，螺旋 VII 的跷跷板运动和细胞外环 3 的移动可能是 A2A 受体及其配体特异的。我们的结果将 UK-432097 定义为一种构象选择性激动剂，能够使受体稳定在特定的活性状态，这与其他采样多种构象状态的 GPCR 激动剂不同。