Uehara Yutaka, Mochizuki Masato, Matsuno Kenji, Haino Takeharu, Asai Akira
Center for Drug Discovery, Graduate School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka 422-8526, Japan.
Biochem Biophys Res Commun. 2009 Mar 13;380(3):627-31. doi: 10.1016/j.bbrc.2009.01.137. Epub 2009 Jan 27.
Constitutive activation of the oncogenic transcription factor STAT3 frequently occurs in various human malignancies. STAT3 activation involves dimerization via intermolecular pTyr-SH2 interaction. Thus, antagonizing this interaction is a feasible approach to inhibit STAT3 activation for cancer therapy. In order to identify selective STAT3 inhibitors, we developed a biochemical HTS system based on AlphaScreen technology, which measures the abilities of test compounds to antagonize pTyr-SH2 interactions. We screened our chemical libraries using this system and identified 5,15-diphenylporphyrin (5,15-DPP) as a selective STAT3-SH2 antagonist. Selective inhibition of STAT3 nuclear translocation and DNA biding activity was observed in cells treated with 5,15-DPP. IL-6-dependent dimerization of STAT3, c-myc promoter binding and c-myc protein expression were all suppressed by 5,15-DPP, whereas no decrement in either expression or phosphorylation level of STAT3 was observed. Thus, the HTS assay system represented herein may be useful for identifying novel STAT3-SH2 antagonists.
致癌转录因子STAT3的组成性激活在多种人类恶性肿瘤中频繁发生。STAT3激活涉及通过分子间pTyr-SH2相互作用形成二聚体。因此，拮抗这种相互作用是抑制STAT3激活以进行癌症治疗的一种可行方法。为了鉴定选择性STAT3抑制剂，我们基于AlphaScreen技术开发了一种生化高通量筛选系统，该系统可测量测试化合物拮抗pTyr-SH2相互作用的能力。我们使用该系统筛选了我们的化学文库，并鉴定出5,15-二苯基卟啉（5,15-DPP）作为选择性STAT3-SH2拮抗剂。在用5,15-DPP处理的细胞中观察到STAT3核转位和DNA结合活性的选择性抑制。STAT3的IL-6依赖性二聚化、c-myc启动子结合和c-myc蛋白表达均被5,15-DPP抑制，而未观察到STAT3的表达或磷酸化水平有任何降低。因此，本文介绍的高通量筛选测定系统可能有助于鉴定新型STAT3-SH2拮抗剂。
