Helicobacter pylori colonises the stomach of approximately 50% of the global population. Cytotoxin-associated gene A protein (CagA) is one of the important virulent factors responsible for the increased inflammation and increases the risk of developing peptic ulcers and gastric carcinoma. The cytokine interleukin-6 (IL-6) has particularly important roles in the malignant transformation of gastric and intestinal epithelial cells as it is upregulated in H. pylori-infected gastric mucosa. In this study, we investigated the underlying mechanisms of CagA-induced IL-6 up-regulation during H. pylori infection. AGS cells, a human gastric adenocarcinoma cell line, lacking eEF1A1 were infected with CagA+H. pylori (NCTC11637), CagA−H. pylori (NCTC11637ΔcagA), or transduced by Ad-cagA/Ad-GFP. The expression and production of IL-6 were measured by quantitative real-time reverse transcription polymerase chain reaction and enzyme-linked immunosorbent assay, respectively. The interactions among CagA, eukaryotic translation elongation factor 1-alpha 1 (eEF1A1), protein kinase Cδ (PKCδ), and signal transducer and activator of transcription 3 (STAT3) were determined by western blot or co-immunoprecipitation. During H. pylori infection, CagA-M (residues 256‒871aa) was found to interact with eEF1A1-I (residues 1‒240aa). NCTC11637 increased the expression of IL-6 in AGS cells compared with NCTC11637ΔcagA whereas knockdown of eEF1A1 in AGS cells completely abrogated these effects. Moreover, the CagA-eEF1A1 complex promoted the expression of IL-6 in AGS cells. CagA and eEF1A1 cooperated to mediate the expression of IL-6 by affecting the activity of p-STATS727 in the nucleus. Further, CagA-eEF1A1 affected the activity of STAT3 by recruiting PKCδ. However, blocking PKCδ inhibited the phosphorylation of STAT3S727 and induction of IL-6 by CagA. CagA promotes the expression of IL-6 in AGS cells by recruiting PKCδ through eEF1A1 in the cytoplasm to increase the phosphorylation of STAT3S727 in the nucleus. These findings provide new insights into the function of CagA-eEF1A1 interaction in gastric adenocarcinoma.

中文翻译：

---

CagA 协调 eEF1A1 和 PKCδ 在幽门螺杆菌感染的胃上皮细胞中诱导白细胞介素 6 的表达。

幽门螺杆菌在全球约 50% 的人口的胃中定殖。细胞毒素相关基因 A 蛋白 (CagA) 是导致炎症增加并增加发生消化性溃疡和胃癌的风险的重要毒力因素之一。细胞因子白细胞介素 6 (IL-6) 在胃和肠上皮细胞的恶性转化中具有特别重要的作用，因为它在幽门螺杆菌感染的胃粘膜中上调。在这项研究中，我们研究了在幽门螺杆菌感染期间 CagA 诱导的 IL-6 上调的潜在机制。缺乏 eEF1A1 的人胃腺癌细胞系 AGS 细胞被 CagA+H 感染。幽门螺杆菌（NCTC11637），CagA-H。pylori (NCTC11637ΔcagA)，或由 Ad-cagA/Ad-GFP 转导。分别通过定量实时逆转录聚合酶链反应和酶联免疫吸附测定法测量IL-6的表达和产生。CagA、真核翻译延伸因子 1-α 1 (eEF1A1)、蛋白激酶 Cδ (PKCδ) 和信号转导和转录激活因子 3 (STAT3) 之间的相互作用通过蛋白质印迹或免疫共沉淀确定。在幽门螺杆菌感染期间，发现 CagA-M（残基 256-871aa）与 eEF1A1-I（残基 1-240aa）相互作用。与 NCTC11637ΔcagA 相比，NCTC11637 增加了 AGS 细胞中 IL-6 的表达，而 AGS 细胞中 eEF1A1 的敲低完全消除了这些影响。此外，CagA-eEF1A1 复合物促进了 AGS 细胞中 IL-6 的表达。CagA 和 eEF1A1 通过影响细胞核中 p-STATS727 的活性来协同介导 IL-6 的表达。此外，CagA-eEF1A1 通过募集 PKCδ 影响 STAT3 的活性。然而，阻断 PKCδ 抑制了 STAT3S727 的磷酸化和 CagA 对 IL-6 的诱导。CagA 通过细胞质中的 eEF1A1 募集 PKCδ 来促进 AGS 细胞中 IL-6 的表达，从而增加细胞核中 STAT3S727 的磷酸化。这些发现为 CagA-eEF1A1 相互作用在胃腺癌中的作用提供了新的见解。CagA 通过细胞质中的 eEF1A1 募集 PKCδ 来促进 AGS 细胞中 IL-6 的表达，从而增加细胞核中 STAT3S727 的磷酸化。这些发现为 CagA-eEF1A1 相互作用在胃腺癌中的作用提供了新的见解。CagA 通过细胞质中的 eEF1A1 募集 PKCδ 来促进 AGS 细胞中 IL-6 的表达，从而增加细胞核中 STAT3S727 的磷酸化。这些发现为 CagA-eEF1A1 相互作用在胃腺癌中的作用提供了新的见解。