Down-regulation of Bcl-2 is mediated by NF-κB activation in Helicobacter pylori- induced apoptosis of gastric epithelial cells

Nursing Policy and Research Institute, Biobehavioral Research Center, Yonsei University College of Nursing, Seoul, Korea.
Scandinavian Journal of Gastroenterology (Impact Factor: 2.36). 10/2010; 46(2):148-55. DOI: 10.3109/00365521.2010.525255
Source: PubMed


Bcl-2 family is involved in the regulation of apoptosis. NF-κB activation is associated with either the expression of Bcl-2 or down-regulation of Bcl-2 depending on cell types and stimuli. Previously, we showed NF-κB activation, decrease in the level of Bcl-2, and apoptosis in Helicobacter pylori (H. pylori)-infected gastric epithelial cells. The present study aims to investigate the relation of Bcl-2 expression and NF-κB activation in H. pylori-induced apoptotic cell death of AGS (gastric adenocarcinoma) cells.
AGS cells were transfected with mutant IκBα to suppress NF-κB activation or Bcl-2 gene to induce overexpression of Bcl-2. mRNA expression of Bcl-2, p53 and Bax, DNA fragmentation, cell viability, and the numbers of apoptotic cells were determined.
H. pylori induced decrease in Bcl-2, but increase in p53 and Bax at the levels of mRNA and protein in AGS cells. H. pylori-induced increment of apoptotic cells and decrease in Bcl-2 level were inhibited in the cells transfected with mutant IκBα gene as compared with the cells transfected with control vector. H. pylori-induced apoptosis determined by apoptotic cells, DNA fragmentation, and cell viability was inhibited in the cells transfected with Bcl-2 gene.
Down-regulation of Bcl-2 is mediated by NF-κB activation, which may be the underlying mechanism of apoptosis in H. pylori-infected gastric epithelial cells.

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    • "Moreover, Bcl-2 proteins control the release of mitochondrial cyt c by regulating mitochondrial permeability. Recent studies have shown that NF-κB acts upstream of apoptosis-related genes, including Bcl-2 [52]. In this study, we found that treatment with an NO donor inhibited Bcl-2 expression. "
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    • "Monocyte-derived human dendritic cells release cytokines and increase expression of major histocompatibility class II proteins [21]. Moreover, H. pylori infection can enhance cell proliferation [8], [22] as to retrieve gastric mucosa damage and apoptosis of gastric epithelial cells [18], [23]. Thus, to counteract H. pylori infection, host activates gene transcription involved in defense mechanism, inflammatory and immunological reaction, cell proliferation and apoptosis. "
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