Hypoxia-induced Transcriptional Activation and Increased mRNA Stability of Vascular Endothelial Growth Factor in C6 Glioma Cells

doi:10.1074/jbc.270.34.19761

Hypoxia-induced Transcriptional Activation and Increased mRNA Stability of Vascular Endothelial Growth Factor in C6 Glioma Cells (*)

From the Max-Planck-Institut für physiologische und klinische Forschung, W. G. Kerckhoff-Institut, Abteilung Molekulare Zellbiologie, Parkstraβe 1, 61231 Bad Nauheim, Germany

^¶To whom correspondence should be addressed:
Max-Planck-Institut für physiologische und klinische, Forschung, Abteilung Molekulare Zellbiologie, Parkstraβe 1, 61231 Bad Nauheim, Germany
. Fax: 49-6032-72259; Tel.: 49-6032-705278.

↵^§ Current address: Ludwig Institute for Cancer Research, Melbourne Tumour Biology Branch, Royal Melbourne Hospital, Victoria 3050, Australia.

Abstract

Vascular endothelial growth factor (VEGF) is an endothelial specific angiogenic mitogen secreted from various cell types including tumor cells. Increasing evidence suggests that VEGF is a major regulator of physiological and pathological angiogenesis, and the VEGF/VEGF receptor system has been shown to be necessary for glioma angiogenesis. Hypoxia seems to play a critical role in the induction of VEGF expression during glioma progression. C6 glioma cells provide an in vivo glioma model for the study of tumor angiogenesis, and the expression of VEGF in C6 cells has been shown to be up-regulated by hypoxia in vitro. However, little is known about the molecular mechanism of hypoxic induction of VEGF. Here, we demonstrate that hypoxic induction of VEGF in C6 cells is due to both transcriptional activation and increased stability of mRNA. Nuclear run-on assays revealed a fast and lasting transcriptional activation, whereas the determination of mRNA half-life showed a slower increase of mRNA stability during hypoxia. Reporter gene studies revealed that hypoxia responsive transcription-activating elements were present in the 5′-flanking region of the VEGF gene. These results suggested that several distinct molecular mechanisms were involved in hypoxia-induced gene expression and were activated in a biphasic manner.

Footnotes

↵* This work was supported in part by the German-Israeli Foundation and the Alexander von Humboldt Foundation. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore by hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.
↵¹ The abbreviations used are:

VEGF

vascular endothelial growth factor

EPO

erythropoietin

Pipes

1,4-piperazinediethanesulfonic acid

kb

kilobase(s)

bp

base pair(s).
↵²Breier, G., Clauss, M., and Risau, W., Dev. Dynamics, in press.
↵³E. Ikeda and W. Risau, unpublished data.
- Received March 13, 1995.
- Revision received June 13, 1995.