Article Text

PDF
Original article
Helicobacter pylori-induced cell death is counteracted by NF-κB-mediated transcription of DARPP-32
  1. Shoumin Zhu1,
  2. Mohammed Soutto1,
  3. Zheng Chen1,
  4. DunFa Peng1,
  5. Judith Romero-Gallo2,
  6. Uma S Krishna2,
  7. Abbes Belkhiri1,
  8. M Kay Washington3,
  9. Richard Peek2,
  10. Wael El-Rifai1,4,5
  1. 1Department of Surgery, Vanderbilt University Medical Center, Nashville, Tennessee, USA
  2. 2Department of Medicine, Vanderbilt University Medical Center, Nashville, Tennessee, USA
  3. 3Department of Pathology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
  4. 4Department of Cancer Biology, Vanderbilt University Medical Center, Nashville, Tennessee, USA
  5. 5Department of Veterans Affairs, Tennessee Valley Healthcare System, Nashville, Tennessee, USA
  1. Correspondence to Professor Wael El-Rifai, Vanderbilt Ingram Cancer Center, Vanderbilt University Medical Center, 760 PRB, 2220 Pierce Avenue, Nashville TN 37232-6308, USA; wael.el-rifai{at}vanderbilt.edu

Abstract

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-κB 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-κB reporter and p-NF-κB (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-α 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-κB-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-κB and DARPP-32 expression levels in gastric cancer tissues (r2=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-κB provides a link between infection, inflammation and gastric tumourigenesis.

  • GASTRIC CANCER
  • HELICOBACTER PYLORI
  • GASTRIC INFLAMMATION

Statistics from Altmetric.com

Request permissions

If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.

Linked Articles