Article Text

other Versions

PDF
Original article
In oesophageal squamous cells, nitric oxide causes S-nitrosylation of Akt and blocks SOX2 (sex determining region Y-box 2) expression
  1. Kiyotaka Asanuma1,2,3,
  2. Xiaofang Huo1,2,
  3. Agoston Agoston4,
  4. Xi Zhang1,2,
  5. Chunhua Yu1,2,
  6. Edaire Cheng1,5,
  7. Qiuyang Zhang1,2,
  8. Kerry B Dunbar1,2,
  9. Thai H Pham1,6,
  10. David H Wang1,2,7,
  11. Katsunori Iijima3,
  12. Tooru Shimosegawa3,
  13. Robert D Odze4,
  14. Stuart J Spechler1,2,7,
  15. Rhonda F Souza1,2,7
  1. 1Esophageal Diseases Center, VA North Texas Health Care System and the University of Texas Southwestern Medical Center, Dallas, Texas, USA
  2. 2Departments of Medicine, VA North Texas Health Care System and the University of Texas Southwestern Medical Center, Dallas, Texas, USA
  3. 3Division of Gastroenterology, Tohoku University Graduate School of Medicine, Sendai, Miyagi, Japan
  4. 4Department of Pathology, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts, USA
  5. 5Department of Pediatrics, Children's Medical Center and the University of Texas Southwestern Medical Center, Dallas, Texas, USA
  6. 6Department of Surgery, VA North Texas Health Care System and the University of Texas Southwestern Medical Center, Dallas, Texas, USA
  7. 7The Harold C. Simmons Comprehensive Cancer Center, University of Texas Southwestern Medical Center, Dallas, Texas, USA
  1. Correspondence to Dr Rhonda F Souza, Department of Gastroenterology, MC# 111B1, Dallas VA Medical Center, 4500 South Lancaster Road, Dallas, TX 75216, USA; rhonda.souza{at}utsouthwestern.edu

Abstract

Objective Barrett's metaplasia might develop if GORD causes oesophageal squamous cells to convert into columnar cells. Acid and bile exposures upregulate columnar differentiation genes like CDX2 in oesophageal squamous cells, but it is not known if such exposures downregulate squamous differentiation genes like SOX2. In addition to acid and bile, patients with GORD also have high oesophageal concentrations of nitric oxide (NO). This study aims to determine how acid, bile salts and NO affect genes that influence oesophageal cell phenotype.

Design Oesophageal squamous cells from patients with Barrett's oesophagus were exposed to acidic bile salts or NOC-9 (an NO donor). SOX2, p63 (squamous transcription factor) and CDX2 mRNAs were measured by quantitative RT-PCR. SOX2 and its regulatory Akt pathway proteins were evaluated by western blotting. S-nitrosylation by NO was blocked by dithiothreitol. Immunohistochemistry for SOX2 was performed on the oesophagus of rats with surgically induced GORD which were fed diets with and without nitrite supplementation.

Results In oesophageal squamous cells, NO profoundly decreased SOX2 protein and caused a significantly greater decrease in SOX2 mRNA than did acidic bile salts. NO also decreased p63 and increased CDX2 expression. NO caused S-nitrosylation of Akt, blocking its phosphorylation. Akt pathway inhibition by LY294002 or Akt siRNA reduced SOX2 mRNA. Rats fed with nitrite-supplemented diets exhibited weaker SOX2 oesophageal staining than rats fed with normal diets.

Conclusions In oesophageal squamous cells, NO blocks SOX2 expression through Akt S-nitrosylation. NO also increases CDX2 and decreases p63 expression. By triggering molecular events preventing squamous differentiation while promoting intestinal differentiation, NO might contribute to Barrett's pathogenesis.

  • BARRETT'S METAPLASIA
  • GASTROESOPHAGEAL REFLUX DISEASE
  • NITRIC OXIDE

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.