Duncan James S, Gyenis Laszlo, Lenehan John, Bretner Maria, Graves Lee M, Haystead Timothy A, Litchfield David W
Department of Biochemistry, The University of Western Ontario, London, Ontario N6A 5C1, Canada.
Mol Cell Proteomics. 2008 Jun;7(6):1077-88. doi: 10.1074/mcp.M700559-MCP200. Epub 2008 Feb 7.
Recently protein kinases have emerged as some of the most promising drug targets; and therefore, pharmaceutical strategies have been developed to inhibit kinases in the treatment of a variety of diseases. CK2 is a serine/threonine-protein kinase that has been implicated in a number of cellular processes, including maintenance of cell viability, protection of cells from apoptosis, and tumorigenesis. Elevated CK2 activity has been established in a number of cancers where it was shown to promote tumorigenesis via the regulation of the activity of various oncogenes and tumor suppressor proteins. Consequently the development of CK2 inhibitors has been ongoing in preclinical studies, resulting in the generation of a number of CK2-directed compounds. In the present study, an unbiased evaluation of CK2 inhibitors 4,5,6,7-tetrabromo-1H-benzotriazole (TBB), 4,5,6,7-tetrabromo-1H-benzimidazole (TBBz), and 2-dimethylamino-4,5,6,7-tetrabromo-1H-benzimidazole (DMAT) was carried out to elucidate the mechanism of action as well as inhibitor specificity of these compounds. Utilizing a chemoproteomics approach in conjunction with inhibitor-resistant mutant studies, CK2alpha and CK2alpha' were identified as bona fide targets of TBB, TBBz, and DMAT in cells. However, inhibitor-specific cellular effects were observed indicating that the structurally related compounds had unique biological properties, suggesting differences in inhibitor specificity. Rescue experiments utilizing inhibitor-resistant CK2 mutants were unable to rescue the apoptosis associated with TBBz and DMAT treatment, suggesting the inhibitors had off-target effects. Exploitation of an unbiased chemoproteomics approach revealed a number of putative off-target inhibitor interactions, including the discovery of a novel TBBz and DMAT (but not TBB) target, the detoxification enzyme quinone reductase 2 (QR2). The results described in the present study provide insight into the molecular mechanism of action of the inhibitors as well as drug specificity that will assist in the development of more specific next generation CK2 inhibitors.
最近，蛋白激酶已成为一些最有前景的药物靶点；因此，已经制定了药物策略来抑制激酶以治疗多种疾病。CK2是一种丝氨酸/苏氨酸蛋白激酶，它与许多细胞过程有关，包括维持细胞活力、保护细胞免受凋亡以及肿瘤发生。在许多癌症中已证实CK2活性升高，在这些癌症中，它通过调节各种癌基因和肿瘤抑制蛋白的活性来促进肿瘤发生。因此，CK2抑制剂的研发一直在临床前研究中进行，产生了许多针对CK2的化合物。在本研究中，对CK2抑制剂4,5,6,7-四溴-1H-苯并三唑（TBB）、4,5,6,7-四溴-1H-苯并咪唑（TBBz）和2-二甲基氨基-4,5,6,7-四溴-1H-苯并咪唑（DMAT）进行了无偏评估，以阐明这些化合物的作用机制以及抑制剂特异性。利用化学蛋白质组学方法结合抗抑制剂突变体研究，确定CK2α和CK2α'是细胞中TBB、TBBz和DMAT的真正靶点。然而，观察到了抑制剂特异性的细胞效应，表明结构相关的化合物具有独特的生物学特性，这表明抑制剂特异性存在差异。利用抗抑制剂CK2突变体进行的拯救实验无法拯救与TBBz和DMAT处理相关的凋亡，这表明抑制剂具有脱靶效应。利用无偏化学蛋白质组学方法揭示了许多假定的脱靶抑制剂相互作用，包括发现一种新型的TBBz和DMAT（但不是TBB）靶点，即解毒酶醌还原酶2（QR2）。本研究中描述的结果为抑制剂的分子作用机制以及药物特异性提供了见解，这将有助于开发更具特异性的下一代CK2抑制剂。
