Hypoxia-Inducible Factor 1 Regulates Vascular Endothelial... : Pancreas (original) (raw)

Article

Hypoxia-Inducible Factor 1 Regulates Vascular Endothelial Growth Factor Expression in Human Pancreatic Cancer

Büchler, Peter*; Reber, Howard A.*; Büchler, Manuela*; Shrinkante, Shailesh†; Büchler, Markus W.†; Friess, Helmut†; Semenza, Gregg L.‡; Hines, Oscar J.*

*Department of Surgery, UCLA School of Medicine, Los Angeles, California, U.S.A.; †Department of Surgery, University of Heidelberg, Germany; and ‡Departments of Pediatrics and Medicine and Institute of Genetic Medicine, The Johns Hopkins University, School of Medicine, Baltimore, Maryland, U.S.A.

Manuscript received March 21, 2002;

revised manuscript accepted June 24, 2002.

Address correspondence and reprint requests to Dr. Oscar J. Hines, Division of General Surgery, UCLA School of Medicine, 72–215 CHS, 10833 Le Conte Avenue, Los Angeles, CA 90095–6904. E-mail: [email protected]

Abstract

Introduction

The microenvironment of low oxygen that is present in human pancreatic cancer in vivo may actively influence tumor growth as well as neovascularization.

Aims

To determine whether hypoxia-inducible factor 1 (HIF-1) is specifically activated by hypoxia in vitro in pancreatic cancer cells and correlated these findings with tumor specimens.

Methodology

Hypoxic regulation of vascular endothelial growth factor (VEGF) was studied by northern blot analysis and enzyme-linked immunosorbent assay. Electrophoretic mobility shift assays and western blot analysis were used to demonstrate hypoxic activation of HIF-1. The relationship between HIF-1 and VEGF in human pancreatic cancer specimens was studied by immunohistochemical analysis, northern blot analysis, and in situ hybridization.

Results

Studies in vivo of human pancreatic cancer tissue showed co-localization of VEGF mRNA, which is produced in ductal cancer cells, and HIF-1α protein, which was detectable in cell nuclei of the same cells. HIF-1α mRNA expression was dramatically upregulated (≈13-fold) in these specimens as well. In vitro, all pancreatic cancer cell lines increased VEGF production when exposed to low oxygen levels, by highly specific activation of HIF-1 DNA binding activity to the VEGF promoter. Cancer cell lines with high constitutive levels of HIF-1α protein were found to produce higher basal levels of VEGF.

Conclusion

We conclude that HIF-1 is the regulatory link between tumor hypoxia and VEGF production in pancreatic cancer, thus establishing a biochemical pathway between tumor hypoxia and neoangiogenesis in this highly aggressive neoplasm.