Therapeutic Application of Novel Stat3 Inhibitors in Breast and Pancreatic Cancer

描述(申请人提供)：项目概述许多人类癌症，包括乳腺癌和胰腺癌，都含有异常的STAT3，它是促进肿瘤形成和发展的主要调节因素。在小鼠模型中，阻断异常的STAT3活性可诱导肿瘤细胞的生长抑制和凋亡，以及肿瘤的消退。鉴于人类肿瘤中STAT3活性异常的数量，STAT3抑制剂作为新型抗癌药物具有很高的商业潜力。此外，有效和选择性的STAT3抑制剂将为询问STAT3信号提供极好的分子探针，以促进我们对该蛋白介导肿瘤发生的分子机制的理解，并为抑制该异常蛋白的功能提供新的方向。通过利用STAT3激活的关键结构要求的计算建模，以及对NCI的多样性和平板化SET化学文库的电子筛选，我们确定NSC 42067、NSC 59263和NSC 74859是STAT3-SH2结构域的结合体和STAT3DNA结合活性的抑制剂(IC50值为65-86和lt；M)。在前期工作中，药物在异种移植瘤中诱导选择性抗肿瘤细胞效应和乳腺肿瘤消退，从而为探索它们作为分子探针和新型抗癌药物设计提供了理论基础。虽然预计药物会与STAT3-SH2结构域相互作用，但STAT3抑制的确切模式尚不清楚。我们的总体目标是应用一种综合的多学科方法来批判性地探索这些分子的结构、分子和生物学特性，并利用它们的结构特性来促进设计有效、选择性和有效的类似物。我们假设42067、59263、74859或类似物与STAT3-SH2结构域相互作用，抑制STAT3的功能，并诱导含有异常STAT3的肿瘤的消退。该假说将通过以下具体目标进行检验：(1)探讨42067、59263、74859或类似物与STAT3的体外生化相互作用。对与STAT3的相互作用进行生化、生物物理和结构分析；(2)利用结构信息优化分子，以提高效力和选择性。使用Aim 1的结构信息和建模，以便于设计更有效、更有选择性和更有效的类似物；(3)确定选定药物在体外对乳腺和胰腺癌细胞的生化、分子和生物学效应；以及(4)测试选定药物对乳腺和胰腺肿瘤生长、转移和异种移植血管生成的影响。研究将测量抗肿瘤效果，并探讨体内潜在的分子机制。这些都是重要的研究，将确定药物的分子和生物学特性，并寻找具有抗肿瘤活性的有效的STAT3选择性抑制剂，以开发成新型抗癌药物。公共卫生相关性：许多人类癌症都有异常的STAT3活性，它作为促进肿瘤形成和进展的事件的主调节因子发挥作用。阻断异常的STAT3活性可在小鼠模型中诱导癌细胞生长抑制、细胞凋亡和肿瘤消退。有效和选择性的STAT3抑制剂是询问STAT3信号的优秀研究工具，以促进我们对致癌机制的理解，并代表潜在的新的抗癌药物。我们的建议将新型药物的分子和生物学特性定义为具有抗肿瘤活性的STAT3选择性抑制剂，这些药物可能适合开发成新型抗癌药物。

DESCRIPTION (provided by applicant): Project Summary Many human cancers, including breast and pancreatic cancers, harbor aberrant Stat3 that functions as a master regulator of events that promote tumor formation and progression. Blocking aberrant Stat3 activity induces cancer cell growth inhibition and apoptosis, and tumor regression in mouse models. Given the number of human tumors with aberrant Stat3 activity, there is a high commercial potential for Stat3 inhibitors as novel anticancer drugs. Moreover, effective and selective Stat3 inhibitors will provide excellent molecular probes to interrogate Stat3 signaling to advance our understanding of the molecular mechanisms by which this protein mediates carcinogenesis, and provide new directions to thwart the functions of the aberrant protein. By computational modeling that exploited the key structural requirements for Stat3 activation, together with in silico screening of the NCI's Diversity and Plated sets chemical libraries, we identified agents, NSC 42067, NSC 59263 and NSC 74859, as binders of Stat3-SH2 domain and inhibitors of Stat3 DNA-binding activity (IC50 of 65-86 <M). In preliminary work, agents induced selective antitumor cell effects and breast tumor regression in xenografts, thereby providing the rationale for exploring them as molecular probes and for novel anticancer drug design. While agents are predicted to interact with the Stat3-SH2 domain, the exact mode of Stat3 inhibition is unknown. Our overall objective is to apply an integrated multi-disciplinary approach to critically explore the structural, molecular and biological properties of these molecules and to capitalize on their structural properties to facilitate the design of potent, selective and efficacious analogs. We hypothesize 42067, 59263, 74859, or analogs interact with the Stat3-SH2 domain, inhibit Stat3 function, and induce the regression of tumors harboring aberrant Stat3. The hypothesis will be tested by the following Specific Aims: (1) To probe the biochemical interactions of 42067, 59263, 74859, or analogs with Stat3 in vitro. Perform biochemical, biophysical, and structural analyses of interactions with Stat3; (2) To use structural information to optimize molecules for enhanced potency and selectivity. Use structural information from Aim 1 and modeling to facilitate the design of more potent, selective, and efficacious analogs; (3) To define the biochemical, molecular and biological effects of select agents in breast and pancreatic cancer cells in vitro; and (4) To test select agents for effects on breast and pancreatic tumor growth, metastasis, and angiogenesis in xenografts. Studies will measure antitumor effects and investigate underlying molecular mechanisms in vivo. These are important studies that will define the molecular and biological properties of agents, and identify potent Stat3-selective inhibitors with antitumor activity for development into novel anticancer drugs. PUBLIC HEALTH RELEVANCE: Many human cancers harbor abnormal Stat3 activity that functions as a master regulator of events that promote tumor formation and progression. Blocking abnormal Stat3 activity induces cancer cell growth inhibition, apoptosis, and tumor regression in mouse models. Effective and selective Stat3 inhibitors are excellent research tools to interrogate Stat3 signaling to advance our understanding of the mechanisms leading to cancer, and represent potential new anticancer agents. Our proposal defines the molecular and biological properties of novel agents as Stat3-selective inhibitors that possess antitumor activity and that may be suitable for development into novel anticancer drugs.