Regulation of RKIP Function by Helicobacter pylori in Gastric Cancer
Regulation of RKIP Function by Helicobacter pylori in Gastric Cancer
Helicobacter pylori (H. pylori) is a gram-negative, spiral-shaped bacterium that infects more than half of the world's population and is a major cause of gastric adenocarcinoma. The mechanisms that link H. pylori infection to gastric carcinogenesis are not well understood. In the present study, we report that the Raf-kinase inhibitor protein (RKIP) has a role in the induction of apoptosis by H. pylori in gastric epithelial cells. Western blot and luciferase transcription reporter assays demonstrate that the pathogenicity island of H. pylori rapidly phosphorylates RKIP, which then localizes to the nucleus where it activates its own transcription and induces apoptosis. Forced overexpression of RKIP enhances apoptosis in H. pylori-infected cells, whereas RKIP RNA inhibition suppresses the induction of apoptosis by H. pylori infection. While inducing the phosphorylation of RKIP, H. pylori simultaneously targets non-phosphorylated RKIP for proteasome-mediated degradation. The increase in RKIP transcription and phosphorylation is abrogated by mutating RKIP serine 153 to valine, demonstrating that regulation of RKIP activity by H. pylori is dependent upon RKIP's S153 residue. In addition, H. pylori infection increases the expression of Snail, a transcriptional repressor of RKIP. Our results suggest that H. pylori utilizes a tumor suppressor protein, RKIP, to promote apoptosis in gastric cancer cells.
- Rhode Island Hospital United States
- Brown University United States
- RHODE ISLAND HOSPITAL
- BROWN UNIVERSITY
STAT3 Transcription Factor, Transcription, Genetic, Science, Apoptosis, Phosphatidylethanolamine Binding Protein, Helicobacter Infections, Bacterial Proteins, Stomach Neoplasms, Cell Line, Tumor, Humans, Phosphorylation, Protein Kinase C, Antigens, Bacterial, Helicobacter pylori, Interleukin-6, Protein Stability, Q, R, Protein Transport, Medicine, Snail Family Transcription Factors, Research Article, Transcription Factors
STAT3 Transcription Factor, Transcription, Genetic, Science, Apoptosis, Phosphatidylethanolamine Binding Protein, Helicobacter Infections, Bacterial Proteins, Stomach Neoplasms, Cell Line, Tumor, Humans, Phosphorylation, Protein Kinase C, Antigens, Bacterial, Helicobacter pylori, Interleukin-6, Protein Stability, Q, R, Protein Transport, Medicine, Snail Family Transcription Factors, Research Article, Transcription Factors
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