Hypoxia-induced reactive oxygen species cause chromosomal abnormalities in endothelial cells in the tumor microenvironment

PLoS One. 2013 Nov 15;8(11):e80349. doi: 10.1371/journal.pone.0080349. eCollection 2013.

Abstract

There is much evidence that hypoxia in the tumor microenvironment enhances tumor progression. In an earlier study, we reported abnormal phenotypes of tumor-associated endothelial cells such as those resistant to chemotherapy and chromosomal instability. Here we investigated the role of hypoxia in the acquisition of chromosomal abnormalities in endothelial cells. Tumor-associated endothelial cells isolated from human tumor xenografts showed chromosomal abnormalities, >30% of which were aneuploidy. Aneuploidy of the tumor-associated endothelial cells was also shown by simultaneous in-situ hybridization for chromosome 17 and by immunohistochemistry with anti-CD31 antibody for endothelial staining. The aneuploid cells were surrounded by a pimonidazole-positive area, indicating hypoxia. Human microvascular endothelial cells expressed hypoxia-inducible factor 1 and vascular endothelial growth factor A in response to either hypoxia or hypoxia-reoxygenation, and in these conditions, they acquired aneuploidy in 7 days. Induction of aneuploidy was inhibited by either inhibition of vascular endothelial growth factor signaling with vascular endothelial growth factor receptor 2 inhibitor or by inhibition of reactive oxygen species by N-acetyl-L-cysteine. These results indicate that hypoxia induces chromosomal abnormalities in endothelial cells through the induction of reactive oxygen species and excess signaling of vascular endothelial growth factor in the tumor microenvironment.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Cycle / genetics
  • Chromosome Aberrations*
  • Chromosomes, Human, Pair 17 / genetics*
  • Endothelial Cells / metabolism*
  • Humans
  • Hypoxia / metabolism
  • Hypoxia / physiopathology*
  • Hypoxia-Inducible Factor 1 / metabolism
  • Karyotype
  • Mice
  • Reactive Oxygen Species / metabolism*
  • Tumor Cells, Cultured
  • Tumor Microenvironment / genetics*
  • Vascular Endothelial Growth Factor A / metabolism
  • Vascular Endothelial Growth Factor Receptor-2 / metabolism

Substances

  • Hypoxia-Inducible Factor 1
  • Reactive Oxygen Species
  • Vascular Endothelial Growth Factor A
  • Vascular Endothelial Growth Factor Receptor-2

Grant support

This article was supported in part by a grant-in-aid for scientific research from the Ministry of Education, Science and Culture of Japan (23112501 and 21659458 to KH). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.