Oxidative stress activates the human histidine decarboxylase promoter in AGS gastric cancer cells
Oxidative stress activates the human histidine decarboxylase promoter in AGS gastric cancer cells
复制标题
DOI：
10.1074/jbc.273.36.23046
复制
发表时间：
1998-09-04
影响因子：
4.8
通讯作者：
Wang, TC
中科院分区：
文献类型：
--
作者：
Höcker, M;Rosenberg, I;Wang, TC
氧化应激被认为在许多胃病的发病机制中发挥着作用。我们最近报道，在胃癌（AGS-B）细胞中，胃泌素通过蛋白激酶C和细胞外信号调节激酶（ERK）依赖性途径刺激组氨酸脱羧酶（HDC）启动子活性，并且这种转录反应是由下游顺式作用元件胃泌素反应元件（GAS-RE）介导的。为了研究氧化应激影响胃细胞的机制，我们研究了过氧化氢 (H2O2) 对 AGS-B 细胞中 HDC 启动子活性和细胞内信号传导的影响。 H2O2 (10 mM) 特异性激活 HDC 启动子 10-12 倍，并且这种激活被甘露醇和 N-乙酰半胱氨酸阻断。过氧化氢处理AGS-B细胞增加了ERK-1和ERK-2的磷酸化和激酶活性，但不影响Jun激酶酪氨酸磷酸化或激酶活性。此外，用H2O2处理AGS-B细胞导致c-fos/c-jun mRNA表达和AP-1活性增加，并且还导致表皮生长因子受体（EGFR）和Shc磷酸化增加。 HDC 启动子活性的 H2O2 依赖性刺激被激酶缺陷型 ERK、显性失活（N17 和 N15）Ras 和显性失活 Raf 完全抑制，并被显性失活 EGFR 突变体部分阻断。相反，蛋白激酶 C 阻断不会抑制 HDC 启动子的 H2O2 依赖性诱导。最后，缺失分析表明 H2O2 响应元件可以定位到基础 HDC 启动子的 GAS-RE（核苷酸 2 至 24）。总体而言，这些研究表明氧化应激通过 GAS-RE 以及至少部分涉及 EGFR 的 Ras、Raf 和 ERK 依赖性途径激活 HDC 启动子。
Oxidant stress is thought to play a role in the pathogenesis of many gastric disorders. We have recently reported that histidine decarboxylase (HDC) promoter activity is stimulated by gastrin through a protein kinase C- and extracellular signal-regulating kinase (ERK)-dependent pathway in gastric cancer (AGS-B) cells, and this transcriptional response is mediated by a downstream cis-acting element, the gastrin response element (GAS-RE). To study the mechanism through which oxidant stress affects gastric cells, we examined the effects of hydrogen peroxide (H2O2) on HDC promoter activity and intracellular signaling in AGS-B cells. H2O2 (10 mM) specifically activated the HDC promoter 10-12-fold, and this activation was blocked by both mannitol and N-acetylcysteine. Hydrogen peroxide treatment of AGS-B cells increased the phosphorylation and kinase activity of ERK-1 and ERK-2, but did not affect Jun kinase tyrosine phosphorylation or kinase activity. In addition, treatment of AGS-B cells with H2O2 resulted in increased c-fos/c-jun mRNA expression and AP-1 activity, and also led to increased phosphorylation of epidermal growth factor receptor (EGFR) and Shc. H2O2-dependent stimulation of HDC promoter activity was completely inhibited by kinase-deficient ERKs, dominant-negative (N17 and N15) Ras, and dominant-negative Raf, and partially blocked by a dominant-negative EGFR mutant. In contrast, protein kinase C blockade did not inhibit H2O2-dependent induction of the HDC promoter. Finally, deletion analysis demonstrated that the H2O2 response element could be mapped to the GAS-RE (nucleotides 2 to 24) of the basal HDC promoter. Overall, these studies suggest that oxidant stress activates the HDC promoter through the GAS-RE, and through an Ras-, Raf-, and ERK-dependent pathway at least partially involving the EGFR.