Lee Jae-Wook, Yang Dong Hee, Park Sojin, Han Hae-Kyoung, Park Jong-Wan, Kim Bo Yeon, Um Sung Hee, Moon Eun-Yi
Department of Bioscience and Biotechnology, Sejong University, Seoul 05006, South Korea.
Department of Pharmacology, College of Medicine, Seoul National University, Seoul 03080, South Korea.
Oncotarget. 2017 Dec 16;9(2):2035-2049. doi: 10.18632/oncotarget.23327. eCollection 2018 Jan 5.
Trichostatin A (TSA) is an anticancer drug that inhibits histone deacetylases (HDACs). Hypoxia-inducible factor 1 (HIF-1) participates in tumor angiogenesis by upregulating target genes, such as vascular endothelial growth factor (VEGF). In the present study, we investigated whether TSA treatment increases HIF-1α stabilization acetylation under normoxic conditions, which would lead to VEGF upregulation and resistance to anticancer drugs. TSA enhanced total HIF-1α and VEGF-HRE reporter activity under normoxic conditions. When cells were transfected with GFP-HIF-1α, treatment with TSA increased the number of green fluorescence protein (GFP)-positive cells. TSA also enhanced the nuclear translocation of HIF-1α protein, as assessed by immunoblotting and as evidenced by increased nuclear localization of GFP-HIF-1α. An increase in the interaction between HIF-1α and the VEGF promoter, which was assessed by a chromatin immunoprecipitation (ChIP) assay, led to activation of the VEGF promoter. TSA acetylated HIF-1α at lysine (K) 674, which led to an increase in TSA-induced VEGF-HRE reporter activity. In addition, TSA-mediated cell death was reduced by the overexpression of HIF-1α but it was rescued by transfection with a HIF-1α mutant (K674R). These data demonstrate that HIF-1α may be stabilized and translocated into the nucleus for the activation of VEGF promoter by TSA-mediated acetylation at K674 under normoxic conditions. These findings suggest that HIF-1α acetylation may lead to resistance to anticancer therapeutics, such as HDAC inhibitors, including TSA.
曲古抑菌素A（TSA）是一种抑制组蛋白脱乙酰酶（HDACs）的抗癌药物。缺氧诱导因子1（HIF-1）通过上调靶基因（如血管内皮生长因子（VEGF））参与肿瘤血管生成。在本研究中，我们调查了TSA处理是否会在常氧条件下增加HIF-1α的稳定性和乙酰化，这将导致VEGF上调和抗癌药物耐药性。TSA在常氧条件下增强了总HIF-1α和VEGF-HRE报告基因活性。当用GFP-HIF-1α转染细胞时，TSA处理增加了绿色荧光蛋白（GFP）阳性细胞的数量。通过免疫印迹评估并由GFP-HIF-1α核定位增加所证实，TSA还增强了HIF-1α蛋白的核转位。通过染色质免疫沉淀（ChIP）分析评估，HIF-1α与VEGF启动子之间的相互作用增加，导致VEGF启动子激活。TSA使HIF-1α在赖氨酸（K）674处乙酰化，这导致TSA诱导的VEGF-HRE报告基因活性增加。此外，HIF-1α的过表达减少了TSA介导的细胞死亡，但用HIF-1α突变体（K674R）转染可挽救这种情况。这些数据表明，在常氧条件下，HIF-1α可能通过TSA介导的K674乙酰化而稳定并转运到细胞核中以激活VEGF启动子。这些发现表明，HIF-1α乙酰化可能导致对抗癌治疗药物（如包括TSA在内的HDAC抑制剂）产生耐药性。
