Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee.
Division of Gastroenterology, Hepatology, and Nutrition, Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee; Veterans Affairs Tennessee Valley Healthcare System, Nashville, Tennessee.
Gastroenterology. 2014 Jun;146(7):1739-51.e14. doi: 10.1053/j.gastro.2014.02.005. Epub 2014 Feb 13.
BACKGROUND & AIMS: The gastric cancer-causing pathogen Helicobacter pylori up-regulates spermine oxidase (SMOX) in gastric epithelial cells, causing oxidative stress-induced apoptosis and DNA damage. A subpopulation of SMOX(high) cells are resistant to apoptosis, despite their high levels of DNA damage. Because epidermal growth factor receptor (EGFR) activation can regulate apoptosis, we determined its role in SMOX-mediated effects.
SMOX, apoptosis, and DNA damage were measured in gastric epithelial cells from H. pylori-infected Egfr(wa5) mice (which have attenuated EGFR activity), Egfr wild-type mice, or in infected cells incubated with EGFR inhibitors or deficient in EGFR. A phosphoproteomic analysis was performed. Two independent tissue microarrays containing each stage of disease, from gastritis to carcinoma, and gastric biopsy specimens from Colombian and Honduran cohorts were analyzed by immunohistochemistry.
SMOX expression and DNA damage were decreased, and apoptosis increased in H. pylori-infected Egfr(wa5) mice. H. pylori-infected cells with deletion or inhibition of EGFR had reduced levels of SMOX, DNA damage, and DNA damage(high) apoptosis(low) cells. Phosphoproteomic analysis showed increased EGFR and erythroblastic leukemia-associated viral oncogene B (ERBB)2 signaling. Immunoblot analysis showed the presence of a phosphorylated (p)EGFR-ERBB2 heterodimer and pERBB2; knockdown of ErbB2 facilitated apoptosis of DNA damage(high) apoptosis(low) cells. SMOX was increased in all stages of gastric disease, peaking in tissues with intestinal metaplasia, whereas pEGFR, pEGFR-ERBB2, and pERBB2 were increased predominantly in tissues showing gastritis or atrophic gastritis. Principal component analysis separated gastritis tissues from patients with cancer vs those without cancer. pEGFR, pEGFR-ERBB2, pERBB2, and SMOX were increased in gastric samples from patients whose disease progressed to intestinal metaplasia or dysplasia, compared with patients whose disease did not progress.
In an analysis of gastric tissues from mice and patients, we identified a molecular signature (based on levels of pEGFR, pERBB2, and SMOX) for the initiation of gastric carcinogenesis.
胃癌病原体幽门螺杆菌在胃上皮细胞中上调精脒氧化酶（SMOX），导致氧化应激诱导的细胞凋亡和 DNA 损伤。尽管 SMOX（高）细胞的 DNA 损伤水平很高，但其中一个亚群细胞对凋亡具有抗性。因为表皮生长因子受体（EGFR）的激活可以调节细胞凋亡，所以我们确定了它在 SMOX 介导的效应中的作用。
在感染了幽门螺杆菌的 Egfr（wa5）小鼠（EGFR 活性减弱）、Egfr 野生型小鼠的胃上皮细胞中或用 EGFR 抑制剂孵育或 EGFR 缺失的感染细胞中，测量 SMOX、细胞凋亡和 DNA 损伤。进行了磷酸蛋白质组学分析。使用免疫组织化学分析了来自哥伦比亚和洪都拉斯队列的每个疾病阶段（从胃炎到癌）的两个独立组织微阵列和胃活检标本。
在感染了幽门螺杆菌的 Egfr（wa5）小鼠中，SMOX 表达和 DNA 损伤减少，细胞凋亡增加。缺失或抑制 EGFR 的幽门螺杆菌感染细胞中 SMOX、DNA 损伤和 DNA 损伤（高）细胞凋亡（低）的水平降低。磷酸蛋白质组学分析显示 EGFR 和红细胞生成性白血病相关病毒癌基因 B（ERBB2）信号增强。免疫印迹分析显示存在磷酸化（p）EGFR-ERBB2 异二聚体和 pERBB2；敲低 ErbB2 促进了 DNA 损伤（高）细胞凋亡（低）细胞的凋亡。SMOX 在胃疾病的所有阶段均增加，在具有肠化生的组织中达到高峰，而 pEGFR、pEGFR-ERBB2 和 pERBB2 主要在显示胃炎或萎缩性胃炎的组织中增加。主成分分析将患有癌症和没有癌症的患者的胃炎组织分开。与疾病未进展到肠化生或异型增生的患者相比，疾病进展到肠化生或异型增生的患者的胃组织中 pEGFR、pEGFR-ERBB2、pERBB2 和 SMOX 增加。
在对来自小鼠和患者的胃组织进行分析后，我们确定了一个分子特征（基于 pEGFR、pERBB2 和 SMOX 的水平），用于启动胃癌的发生。
