Helicobacter pylori Activates IL-6-STAT3 Signaling in Human Gastric Cancer Cells: Potential Roles for Reactive Oxygen Species

• Published in: Helicobacter (Cambridge, Mass.) Vol. 21; no. 5; pp. 405 - 416
• Main Authors: Piao, Juan-Yu, Lee, Hee Geum, Kim, Su-Jung, Kim, Do-Hee, Han, Hyeong-jun, Ngo, Hoang-Kieu-Chi, Park, Sin-Aye, Woo, Jeong-Hwa, Lee, Jeong-Sang, Na, Hye-Kyung, Cha, Young-Nam, Surh, Young-Joon
• Format: Journal Article
• Language: English
• Published: England Blackwell Publishing Ltd 01.10.2016; Wiley Subscription Services, Inc
• Subjects: Blotting, Western; Cell Line, Tumor; Coculture Techniques; Electrophoretic Mobility Shift Assay; Gastric cancer; gastritis; Helicobacter pylori; Helicobacter pylori - immunology; Humans; Immunohistochemistry; Immunoprecipitation; interleukin-6; Interleukin-6 - metabolism; interleukin-6 receptor; Kinases; Oxygen; Phosphorylation; reactive oxygen species; Reactive Oxygen Species - metabolism; Reverse Transcriptase Polymerase Chain Reaction; Rodents; signal transducer and activator of transcription 3; Signal Transduction; STAT3 Transcription Factor - metabolism; Transcriptional Activation; interleukin-6 receptor; signal transducer and activator of transcription 3; Helicobacter pylori; gastritis; interleukin-6; reactive oxygen species
• ISSN: 1083-4389; 1523-5378
• DOI: 10.1111/hel.12298

Background Recent studies have shown that Helicobacter pylori (H. pylori) activates signal transducer and activator of transcription 3 (STAT3) that plays an important role in gastric carcinogenesis. However, the molecular mechanism underlying H. pylori‐mediated STAT3 activation is still not fully understood. In this study, we investigated H. pylori‐induced activation of STAT3 signaling in AGS human gastric cancer cells and the underlying mechanism. Materials and Methods AGS cells were cocultured with H. pylori, and STAT3 activation was assessed by Western blot analysis, electrophoretic mobility shift assay and immunocytochemistry. To demonstrate the involvement of reactive oxygen species (ROS) in H. pylori‐activated STAT3 signaling, the antioxidant N‐acetylcysteine was utilized. The expression and production of interleukin‐6 (IL‐6) were measured by reverse‐transcription polymerase chain reaction and enzyme‐linked immunosorbent assay (ELISA), respectively. The interaction between IL‐6 and IL‐6 receptor (IL‐6R) was determined by the immunoprecipitation assay. Results H. pylori activates STAT3 as evidenced by increases in phosphorylation on Tyr705, nuclear localization, DNA binding and transcriptional activity of this transcription factor. The nuclear translocation of STAT3 was also observed in H. pylori‐inoculated mouse stomach. In the subsequent study, we found that H. pylori‐induced STAT3 phosphorylation was dependent on IL‐6. Notably, the increased IL‐6 expression and the IL‐6 and IL‐6R binding were mediated by ROS produced as a consequence of H. pylori infection. Conclusions H. pylori‐induced STAT3 activation is mediated, at least in part, through ROS‐induced upregulation of IL‐6 expression. These findings provide a novel molecular mechanism responsible for H. pylori‐induced gastritis and gastric carcinogenesis.