期刊
GUT
卷 66, 期 5, 页码 802-812出版社
BMJ PUBLISHING GROUP
DOI: 10.1136/gutjnl-2016-312141
关键词
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资金
- National Cancer Institute [R01CA93999]
- Department of Veterans Affairs
- Vanderbilt SPORE in Gastrointestinal Cancer [P50 CA95103]
- Vanderbilt Ingram Cancer Center [P30 CA68485]
- Vanderbilt Digestive Disease Research Center [DK058404]
Objective DARPP-32 is a frequently amplified and overexpressed gene that promotes several oncogenic functions in gastric cancer. Herein, we investigated the relationship between Helicobacter pylori infection, proinflammatory NF-kappa B activation and regulation of DARPP-32. Design The study used in vivo and in vitro experiments. Luciferase reporter, quantitative real-time PCR, immunoblot, chromatin immunoprecipitation (ChIP), cell viability, H. pylori infection, tissue microarrays and immunohistochemical assays were used. Results Our results indicated that H. pylori infection increased the DARPP-32 mRNA and protein levels in gastric cancer cell lines and gastric mucosa of mice. H. pylori infection increased the activity of NF-kappa B reporter and p-NF-kappa B (S536) protein level in vitro and in vivo. To investigate the transcriptional regulation of DARPP-32, we cloned a 3019 bp of the DARPP-32 promoter into the luciferase reporter (pGL3-Luc). Both H. pylori infection and tumour necrosis factor-a treatment induced DARPP-32 reporter activity (p<0.01). Using deletion constructs of DARPP-32 promoter and ChIP assay, we demonstrated that the sequence -996 to -1008 bp containing putative NF-kappa B-binding sites is the most active region. The induction of DARPP-32 expression by H. pylori infection counteracted H. pylori-induced cell death through activation of serine/threonine-specific protein kinase (AKT), as determined by ATP-Glo and clonogenic survival assays. Immunohistochemistry analysis demonstrated a significant positive correlation between NF-kappa B and DARPP-32 expression levels in gastric cancer tissues (r(2)=0.43, p<0.01). Conclusions Given the high frequency of DARPP-32 overexpression and its prosurvival oncogenic functions, the induction of DARPP-32 expression following H. pylori infection and activation of NF-kappa B provides a link between infection, inflammation and gastric tumourigenesis.
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