Targeting Mitotic Kinases Inhibitors for Cancer Therapy

描述（由申请人提供）：最近伊马替尼治疗费城染色体阳性慢性粒细胞白血病的成功使酪氨酸和丝氨酸/苏氨酸激酶成为癌症治疗的主要靶点。由于目前只有一小部分人类kinome可以被合理选择性和有效的抑制剂靶向，因此迫切需要制定有效发现和优化新抑制剂的策略。为了实现这一目标，我们最近开发了一个atp竞争性激酶抑制剂的化合物库。利用我们收集的新化合物（大约2000种），我们测试了16种培养的肿瘤细胞系，以测试这些化合物诱导凋亡的能力。这项研究发现了一种化合物ON1231320，它对整个16个肿瘤细胞系具有显著的细胞毒性，对正常细胞几乎没有或没有细胞毒性。对285种激酶的激酶抑制实验表明，该化合物对Plk2/Snk具有显著的特异性，Plk2/Snk是一种参与中心体复制和有丝分裂过程的激酶。最重要的是，Plk2最近被认为是连接细胞代谢和细胞周期的激酶之一。在癌细胞中经常观察到对糖酵解依赖性增加的线粒体功能障碍（称为Warburg效应），在线粒体功能障碍条件下识别促进细胞存活的途径具有治疗意义。最近的一项研究表明，在HCT116人结肠癌细胞系中靶向消融SCO2基因会导致线粒体呼吸的消融，而PLK2是SCO2-/-细胞中表达最高的基因。即使在线粒体呼吸缺陷的人类癌细胞中，PLK2水平的适度降低，也会导致它们在小鼠体内形成异种移植物的能力消失。我们的研究结果表明，ON1231320是一种有效的肿瘤细胞死亡诱导剂，在体内具有良好的安全性。我们建议在体外和体内研究该化合物对肿瘤生长的影响，以确定ON1231320如何作为一种新的癌症化疗药物。该提案的目的是：1。测定ON01231320对Plk2的抑制动力学；2. 确定ON1231320对Plk2介导的下游信号事件的影响，并评估其在缺氧、遗传毒性和呼吸缺陷环境下对肿瘤细胞生长的影响；3. 在异种移植物模型中表征ON1231320的PK特性，以确定抑制肿瘤生长所需的Plk2抑制程度，评估ON1231320浓度与化合物抗肿瘤活性的关系，并评估使用PBMN作为替代品的有效性；和4。进一步探讨ON1231320联合奥沙利铂、5-氟尿嘧啶、紫杉醇、阿霉素等细胞毒性抗癌药物在乳腺癌和结直肠癌模型系统中诱导细胞凋亡和肿瘤消退的作用。

DESCRIPTION (provided by applicant): The recent success of imatinib for the treatment of Philadelphia chromosome positive chronic myelogenous leukemia has made tyrosine and serine/threonine kinases major targets for cancer therapy. As only a small fraction of the human kinome can currently be targeted by a reasonably selective and potent inhibitor, there is an urgent need to develop strategies for efficient discovery and optimization of new inhibitors. Towards this goal, we have recently developed a compound library of ATP-competitive kinase inhibitors. Using our collection of novel compounds (approximately 2,000), we tested a panel of 16 cultured tumor cell lines for the ability of these compounds to induce apoptotic death. This search revealed a compound, ON1231320, that had remarkable cytotoxicity against the entire panel of 16 tumor cell lines, with little or no cytotoxicity towards normal cells. Kinase inhibition assays against a panel of 285 kinases revealed that this compound had a remarkable specificity towards Plk2/Snk, a kinase involved in centrosome duplication and mitotic progression. Most importantly, Plk2 has recently been implicated as one of the kinases that links cellular metabolism to cell cycle. Mitochondrial dysfunction with increased dependence on glycolysis is frequently observed in cancer cells (known as the Warburg effect) and identification of pathways that promote cell survival under conditions of mitochondrial dysfunction have therapeutic implications. In a recent study, it has been shown that targeted ablation of SCO2 gene in HCT116 human colon cancer cell line results in the ablation of mitochondrial respiration and that PLK2 is the most highly expressed gene in SCO2-/-cells. Even a modest reduction in PLK2 levels in human cancer cells with defects in mitochondrial respiration results in the elimination of their ability to form xenografts in mice. Our results show that ON1231320 is a potent inducer of tumor cell death and has an excellent safety profile in vivo. We propose to study the effects of this compound on tumor growth in vitro and in vivo to determine how ON1231320 will serve as a novel cancer chemotherapeutic. The aims of the proposal are: 1. To determine the kinetics of inhibition of Plk2 by ON01231320; 2. To determine the effects of ON1231320 on downstream signaling events mediated by Plk2 and evaluate its effect on tumor cell growth under hypoxic, genotoxic and defective respiratory contexts; 3. Characterize the PK properties of ON1231320 in xenograft models to determine the degree of inhibition of Plk2 that is required for inhibition of tumor growth and assess how ON1231320 concentrations are related to antitumor activity of the compound and to evaluate the validity of using PBMN as surrogates; and 4. To further explore the effects of combination therapy using ON1231320 and cytotoxic anti-cancer agents such as oxaliplatin, 5-fluorouracil, paclitaxel and doxorubicin to induce apoptosis and tumor regression in breast and colorectal cancer model systems.