Institute of Medical and Molecular Toxicology, Chung Shan Medical University, Taichung, Taiwan, ROC.
J Agric Food Chem. 2010 Mar 10;58(5):2943-51. doi: 10.1021/jf9043265.
Idiopathic pulmonary fibrosis (IPF) is a progressive chronic disorder characterized by the activation of fibroblasts and the overproduction of extracellular matrix. Fibroblast resistance to apoptosis leads to increased fibrosis. Targeting fibroblasts with apoptotic agents represents a major therapeutic intervention for debilitating IPF. Gallic acid (3,4,5-trihydroxybenzoic acid), a naturally occurring plant phenol, has been reported to induce apoptosis in tumor cell lines and renal fibroblasts. However, the effects of gallic acid on lung fibroblasts have not been investigated. The aim of the present study is to determine the effects of gallic acid on primary cultured mouse fibroblasts. Our results showed that gallic acid induces the apoptotic death of fibroblasts via both intrinsic and extrinsic apoptotic pathways by the elevation of PUMA, Fas, and FasL protein levels. Moreover, intracellular reactive oxygen species (ROS) generation and 8-hydroxy-2'-deoxyguanosine production were observed in gallic acid-stimulated fibroblasts. Mechanistic studies showed that gallic acid induces early phosphorylation of p53(Ser18) and histone 2AX(Ser139) (H2AX) via ataxia telangiectasia mutated (ATM) activation in response to ROS-provoked DNA damage. When mouse lung fibroblasts were treated with caffeine, an ATM kinase inhibitor, the levels of p53, phosphorylated p53(Ser18), and cell death induced by gallic acid were significantly attenuated. Additionally, pretreatment with antioxidants drastically inhibited the gallic acid-induced 8-hydroxy-2'-deoxyguanosine (8-OH-dG) formation and phosphorylation of p53(Ser18) and ATM(Ser1981), as well as apoptosis. Our results provide the first evidence of the activation of ROS-dependent ATM/p53 signaling as a critical mechanism of gallic acid-induced cell death in primary cultured mouse lung fibroblasts.
特发性肺纤维化（IPF）是一种进行性慢性疾病，其特征在于成纤维细胞的激活和细胞外基质的过度产生。成纤维细胞对细胞凋亡的抵抗导致纤维化增加。用凋亡剂靶向成纤维细胞是治疗进行性特发性肺纤维化的主要治疗干预措施。没食子酸（3,4,5-三羟基苯甲酸）是一种天然存在的植物酚，已被报道可诱导肿瘤细胞系和肾成纤维细胞凋亡。然而，没食子酸对肺成纤维细胞的影响尚未得到研究。本研究旨在确定没食子酸对原代培养的小鼠成纤维细胞的影响。我们的结果表明，没食子酸通过上调 PUMA、Fas 和 FasL 蛋白水平，通过内在和外在凋亡途径诱导成纤维细胞凋亡。此外，在没食子酸刺激的成纤维细胞中观察到细胞内活性氧（ROS）的产生和 8-羟基-2'-脱氧鸟苷的产生。机制研究表明，没食子酸通过 ATM 激活诱导 p53（Ser18）和组蛋白 2AX（Ser139）（H2AX）的早期磷酸化，以响应 ROS 引起的 DNA 损伤。当用 ATM 激酶抑制剂咖啡因处理小鼠肺成纤维细胞时，用没食子酸诱导的 p53、磷酸化 p53（Ser18）和细胞死亡水平明显减弱。此外，抗氧化剂预处理可显著抑制没食子酸诱导的 8-羟基-2'-脱氧鸟苷（8-OH-dG）形成以及 p53（Ser18）和 ATM（Ser1981）的磷酸化和细胞凋亡。我们的研究结果提供了ROS 依赖性 ATM/p53 信号通路激活作为没食子酸诱导原代培养的小鼠肺成纤维细胞死亡的关键机制的第一个证据。
