Allosteric drugs targeting Aurora kinases for the treatment of cancer

人们一致认为，未来的癌症治疗将涉及基于肿瘤的特定特征选择的靶向药物的组合，以个性化的医学方法。因此，未来的个性化治疗需要更多的选择性靶向药物，可以用于联合治疗。蛋白激酶是主要的药物靶点，在过去十年中开发了许多针对ATP结合位点的药物。然而，大多数药物都是非选择性的。作为替代方案，人们对蛋白激酶的变构、非ATP结合位点调节剂的开发越来越感兴趣。在过去的12年中，我们发现并表征了AGC蛋白激酶大家族中的变构调节位点（PIF口袋）。我们也是开发技术的先驱，通过用低分子量化合物靶向变构PIF口袋来间接激活或抑制AGC激酶。Aurora激酶（AurA、AurB和AurC）与AGC蛋白激酶密切相关，并且通过辅助蛋白TPX 2和INCENP的结合而被激活，所述辅助蛋白TPX 2和INCENP分别与AurA和AurB的PIF口袋位点结合。极光激酶是细胞分裂的重要调节剂，在多种癌症类型中过表达，并且是用于治疗癌症的有希望的药物靶标。值得注意的是，AurA稳定了N-Myc，在20-30%的儿童癌症神经母细胞瘤中作为致癌伙伴一起起作用。据认为，通过变构化合物抑制AurA激酶将使AurA/N-Myc复合物不稳定，导致N-Myc降解，从而更有效地治疗癌症。作为该应用的初步工作，我们使用中等通量筛选并鉴定了人AurA的低分子量调节剂，其从变构口袋中置换TPX 2，表明了变构作用机制。我们还获得了一种热门化合物PSx 137的详细信息，该化合物在体外抑制AurA活性，促进人类癌细胞细胞周期停滞在G2/S期，并且对培养中的这些细胞有毒。本申请旨在分析PSx 137和其他新鉴定化合物的结构作用机制，并获得与变构化合物复合的Aurora蛋白的晶体结构。结构信息将确认变构化合物的结合位点，并使我们能够理解PIF口袋位点和活性位点之间的变构通信和串扰的机制，这些细节在很大程度上仍然未知。此外，对当前应用的研究将为合理提高极光激酶的这种变构调节剂的效力和选择性以用于抗癌药物的开发提供信息。该项目符合法兰克福大学医院在转化研究方面的主要承诺。

There is consensus that the future treatment of cancer will involve the combination of targeted drugs, selected based on the particular characteristics of the tumors, in a personalized medicine approach. Thus, future personalized therapies require a larger set of selective targeted drugs that could be used in combination therapies. Protein kinases are major drug targets and numerous drugs directed to the ATP-binding site have been developed over the last decade. However, most of those drugs are very unselective. As an alternative, there is increasing interest in the development of allosteric, non-ATP-binding site regulators of protein kinases. Over the last 12 years, we discovered and characterized an allosteric regulatory site (PIF-pocket) in the large family of AGC protein kinases. We were also pioneers in developing the technology to pharmacologically activate or inhibit AGC kinases by targeting the allosteric PIF-pocket with low-molecular-weight compounds. Aurora kinases (AurA, AurB, and AurC) are closely related to AGC protein kinases and are activated by the binding of the auxiliary proteins TPX2 and INCENP, which bind to a PIF-pocket-site of AurA and AurB, respectively. Aurora kinases are important regulators of cell division, are overexpressed in a variety of cancer types, and are promising drug targets for the treatment of cancers. Notably, AurA stabilizes N-Myc, acting together as oncogenic partners in 20-30% of childhood cancer neuroblastoma. It is considered that AurA kinase inhibition by allosteric compounds will destabilize AurA/N-Myc complexes, lead to N-Myc degradation, and thus be more effective for the treatment of cancers. As preliminary work to this application, we used medium-throughput screening and identified low-molecular-weight modulators of human AurA, which displace TPX2 from the allosteric pocket, indicating an allosteric mechanism of action. We also obtained detailed information on one hit compound, PSx137, which inhibits AurA activity in vitro, promotes the arrest of the cell cycle of human cancer cells in the G2/S stage, and is toxic to these cells in culture. The current application aims to analyze the structural mechanism of action of PSx137 and other novel identified compounds and to obtain crystal structures of Aurora proteins in complex with the allosteric compounds. The structural information will confirm the binding site of the allosteric compounds and allow us to understand the mechanisms underlying allosteric communication and crosstalk between the PIF-pocket-site and the active site, details which remain largely unknown. In addition, the research on the current application will provide information for the rational improvement of the potency and selectivity of such allosteric regulators of Aurora kinases for the development of anti-cancer drugs. The project is in line with major undertakings of the Frankfurt University Hospital in translational research.