Solid Tumour Target Discovery Laboratory, Newcastle Cancer Centre, Northern Institute for Cancer Research, Newcastle University, Newcastle upon Tyne, Tyne and Wear, United Kingdom.
PLoS One. 2012;7(10):e45539. doi: 10.1371/journal.pone.0045539. Epub 2012 Oct 8.
Tip60 (KAT5) is a histone acetyltransferase (HAT enzyme) involved in multiple cellular processes including transcriptional regulation, DNA damage repair and cell signalling. In prostate cancer, aggressive cases over-express Tip60 which functions as an androgen receptor co-activator via direct acetylation of lysine residues within the KLKK motif of the receptor hinge region. The purpose of this study was to identify and characterise a Tip60 acetylase inhibitor. High-throughput screening revealed an isothiazole that inhibited both Tip60 and p300 HAT activity. This substance (initially identified as 4-methyl-5-bromoisothiazole) and other isothiazoles were synthesised and assayed against Tip60. Although an authentic sample of 4-methyl-5-bromoisothiazole was inactive against Tip60, in an in vitro HAT assay, 1,2-bis(isothiazol-5-yl)disulfane (NU9056) was identified as a relatively potent inhibitor (IC(50) 2 µM). Cellular activity was confirmed by analysis of acetylation of histone and non-histone proteins in a prostate cancer cell line model. NU9056 treatment inhibited cellular proliferation in a panel of prostate cancer cell lines (50% growth inhibition, 8-27 µM) and induced apoptosis via activation of caspase 3 and caspase 9 in a concentration- and time-dependent manner. Also, decreased androgen receptor, prostate specific antigen, p53 and p21 protein levels were demonstrated in response to treatment with NU9056. Furthermore, pre-treatment with NU9056 inhibited both ATM phosphorylation and Tip60 stabilization in response to ionising radiation. Based on the activity of NU9056 and the specificity of the compound towards Tip60 relative to other HAT enzymes, these chemical biology studies have identified Tip60 as a potential therapeutic target for the treatment of prostate cancer.
Tip60（KAT5）是一种组蛋白乙酰转移酶（HAT 酶），参与多种细胞过程，包括转录调控、DNA 损伤修复和细胞信号转导。在前列腺癌中，侵袭性病例过度表达 Tip60，它通过直接乙酰化受体铰链区域 KLKK 基序内的赖氨酸残基，作为雄激素受体共激活剂发挥作用。本研究的目的是鉴定和表征 Tip60 乙酰转移酶抑制剂。高通量筛选发现一种异噻唑，可抑制 Tip60 和 p300 HAT 活性。该物质（最初鉴定为 4-甲基-5-溴异噻唑）和其他异噻唑被合成并针对 Tip60 进行了测定。尽管 4-甲基-5-溴异噻唑的真实样品对 Tip60 无活性，但在体外 HAT 测定中，1,2-双（异噻唑-5-基）二硫烷（NU9056）被鉴定为相对有效的抑制剂（IC50 为 2 µM）。在前列腺癌细胞模型中分析组蛋白和非组蛋白蛋白的乙酰化，证实了细胞活性。NU9056 处理抑制了一系列前列腺癌细胞系的细胞增殖（50%生长抑制，8-27 µM），并通过 caspase 3 和 caspase 9 的浓度和时间依赖性激活诱导细胞凋亡。此外，NU9056 处理还导致雄激素受体、前列腺特异性抗原、p53 和 p21 蛋白水平降低。此外，NU9056 的预处理抑制了电离辐射后 ATM 磷酸化和 Tip60 的稳定。基于 NU9056 的活性以及该化合物相对于其他 HAT 酶对 Tip60 的特异性，这些化学生物学研究表明 Tip60 是治疗前列腺癌的潜在治疗靶点。
