Gu Meng-Li, Wang Ya-Mei, Zhou Xin-Xin, Yao Hang-Ping, Zheng Song, Xiang Zun, Ji Feng
Department of Gastroenterology, The First Affiliated Hospital of Medical College of Zhejiang University, Hangzhou, Zhejiang 310003, P.R. China.
State Key Laboratory for Diagnosis and Treatment of Infectious Diseases, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang 310003, P.R. China.
Oncol Rep. 2016 Nov;36(5):2763-2770. doi: 10.3892/or.2016.5080. Epub 2016 Sep 12.
Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasm featured by activated mutations of KIT and PDGFRA. Although overall survival rates have greatly improved by the development of receptor tyrosine kinase inhibitors, most patients ultimately acquire resistance due to secondary mutations of KIT or PDGFRA. Inhibition of the histone acetyltransferases (HATs) CREB‑binding protein (CBP) and p300 results in antineoplastic effects in various cancers. To determine whether CBP/p300 can serve as an antineoplastic target for GISTs, specific short interfering RNA sequences and the selective HAT inhibitor C646 were administered to GIST882 cells. Cell viability, apoptosis and the cell cycle were analysed using the Cell Counting Kit-8, a caspase-3/7 activity assay or Annexin V-fluorescein isothiocyanate/propidium iodide (PI) staining and PI staining. Gene and protein expression levels were measured by quantitative real-time polymerase chain reaction and western blotting, respectively. Transcriptional blockage of CBP, rather than p300, resulted in suppression of cell proliferation. Interestingly, both CBP and p300 depletion enhanced caspase-3/7 activity. A lack of CBP and p300 caused ETS translocation variant 1 (ETV1) downregulation and KIT inhibition in GIST cells. Nevertheless, the absence of CBP, not p300, leads to extracellular signal-regulated kinase 1/2 inactivation and c-Jun NH2-terminal kinase activation, suggesting a more crucial role for CBP than p300 in cell proliferation and survival. Furthermore, proliferation of GIST cells was reduced by administration of C646, a selective HAT inhibitor for CBP/p300. Apoptosis induction and cell cycle arrest were detected after exposure to C646, indicating that its antitumor activities were supported by its antiproliferative and proapoptotic effects. Additionally, C646 treatment attenuated ETV1 protein expression and inactivated KIT-dependent pathways. Taken together, the present study suggests that CBP/p300 may serve as novel antineoplastic targets and that use of the selective HAT inhibitor C646 is a promising antitumor strategy for GISTs.
胃肠道间质瘤（GISTs）是最常见的间叶性肿瘤，其特征为KIT和血小板衍生生长因子受体α（PDGFRA）的激活突变。尽管受体酪氨酸激酶抑制剂的发展使总体生存率有了很大提高，但大多数患者最终会因KIT或PDGFRA的二次突变而产生耐药性。抑制组蛋白乙酰转移酶（HATs）中的CREB结合蛋白（CBP）和p300可在多种癌症中产生抗肿瘤作用。为了确定CBP/p300是否可作为GISTs的抗肿瘤靶点，将特异性小干扰RNA序列和选择性HAT抑制剂C646作用于GIST882细胞。使用细胞计数试剂盒-8、半胱天冬酶-3/7活性检测或膜联蛋白V-异硫氰酸荧光素/碘化丙啶（PI）染色以及PI染色来分析细胞活力、凋亡和细胞周期。分别通过定量实时聚合酶链反应和蛋白质印迹法测量基因和蛋白质表达水平。CBP而非p300的转录阻断导致细胞增殖受到抑制。有趣的是，CBP和p300的缺失均增强了半胱天冬酶-3/7的活性。CBP和p300的缺失导致GIST细胞中ETS易位变异体1（ETV1）下调和KIT抑制。然而，CBP而非p300的缺失导致细胞外信号调节激酶1/2失活和c-Jun氨基末端激酶激活，这表明CBP在细胞增殖和存活中比p300发挥更关键的作用。此外，给予C646（一种针对CBP/p300的选择性HAT抑制剂）可降低GIST细胞的增殖。暴露于C646后检测到凋亡诱导和细胞周期停滞，表明其抗肿瘤活性由其抗增殖和促凋亡作用所支持。此外，C646处理减弱了ETV1蛋白表达并使KIT依赖性途径失活。综上所述，本研究表明CBP/p300可能作为新的抗肿瘤靶点，并且使用选择性HAT抑制剂C646是一种有前景的GISTs抗肿瘤策略。
