Pfizer Oncology, Pfizer, San Diego, CA 92121, USA.
Proc Natl Acad Sci U S A. 2010 May 18;107(20):9446-51. doi: 10.1073/pnas.0911863107. Epub 2010 May 3.
Despite abundant evidence that aberrant Rho-family GTPase activation contributes to most steps of cancer initiation and progression, there is a dearth of inhibitors of their effectors (e.g., p21-activated kinases). Through high-throughput screening and structure-based design, we identify PF-3758309, a potent (K(d) = 2.7 nM), ATP-competitive, pyrrolopyrazole inhibitor of PAK4. In cells, PF-3758309 inhibits phosphorylation of the PAK4 substrate GEF-H1 (IC(50) = 1.3 nM) and anchorage-independent growth of a panel of tumor cell lines (IC(50) = 4.7 +/- 3 nM). The molecular underpinnings of PF-3758309 biological effects were characterized using an integration of traditional and emerging technologies. Crystallographic characterization of the PF-3758309/PAK4 complex defined determinants of potency and kinase selectivity. Global high-content cellular analysis confirms that PF-3758309 modulates known PAK4-dependent signaling nodes and identifies unexpected links to additional pathways (e.g., p53). In tumor models, PF-3758309 inhibits PAK4-dependent pathways in proteomic studies and regulates functional activities related to cell proliferation and survival. PF-3758309 blocks the growth of multiple human tumor xenografts, with a plasma EC(50) value of 0.4 nM in the most sensitive model. This study defines PAK4-related pathways, provides additional support for PAK4 as a therapeutic target with a unique combination of functions (apoptotic, cytoskeletal, cell-cycle), and identifies a potent, orally available small-molecule PAK inhibitor with significant promise for the treatment of human cancers.
尽管有大量证据表明，异常的 Rho 家族 GTPase 激活有助于癌症起始和进展的大多数步骤，但它们的效应物（例如，p21 激活激酶）抑制剂却很少。通过高通量筛选和基于结构的设计，我们鉴定出 PF-3758309，这是一种有效的（K(d) = 2.7 nM），ATP 竞争性，吡咯并吡唑抑制剂，可抑制 PAK4。在细胞中，PF-3758309抑制 PAK4 底物 GEF-H1 的磷酸化（IC(50) = 1.3 nM）和一组肿瘤细胞系的无锚定生长（IC(50) = 4.7 +/- 3 nM）。使用传统和新兴技术的集成，对 PF-3758309 的生物学作用的分子基础进行了表征。PF-3758309/PAK4 复合物的晶体结构特征定义了效力和激酶选择性的决定因素。全局高内涵细胞分析证实，PF-3758309 调节已知的 PAK4 依赖性信号节点，并确定与其他途径（例如 p53）的意外联系。在肿瘤模型中，PF-3758309 在蛋白质组学研究中抑制 PAK4 依赖性途径，并调节与细胞增殖和存活有关的功能活性。PF-3758309 阻断多种人类肿瘤异种移植物的生长，在最敏感的模型中，其血浆 EC(50)值为 0.4 nM。这项研究定义了 PAK4 相关途径，为 PAK4 作为具有独特功能组合（凋亡，细胞骨架，细胞周期）的治疗靶标提供了更多支持，并鉴定出一种有效的，可口服的小分子 PAK 抑制剂，具有治疗人类癌症的巨大潜力。
