Hypoxia inducible factor 1α-mediated LOX expression correlates with migration and invasion in epithelial ovarian cancer

Int J Oncol. 2013 May;42(5):1578-88. doi: 10.3892/ijo.2013.1878. Epub 2013 Mar 29.

Abstract

This study investigated the role of LOX in promoting invasion and metastasis of epithelial ovarian cancer in a hypoxic environment and its specific signal transduction pathway. Immunohistochemical detection of HIF-1α and LOX protein expression was performed on formalin-fixed paraffin sections of normal ovary, benign ovarian tumors, borderline and malignant epithelial ovarian tumor paraffin sample, using Mann-Whitney U test for independent comparisons and Wilcoxon signed-ranks test for paired comparisons. HIF-1α and LOX were knocked down in epithelial ovarian cancer cells (EOC), and HIF-1α/LOX regulation mechanism and LOX catalytic activity under hypoxia/reoxygenation microenvironment were explored. Cell migration and invasion ability in LOX inhibited HO8910 cells were investigated under hypoxia/reoxygenation conditions, using matrigel cell invasion and migration assays. We found that HIF-1α and LOX are highly expressed in epithelial ovarian cancer tissues, and the expression of both proteins is significantly correlated with the tumor grade, tumor diameter and lymph node metastasis. HIF-1α expression is positively correlated with the expression of LOX. Specifically, the expression of LOX and HIF-1α markedly increases under hypoxic conditions and decreases after reoxygenation. siRNA knockdown of LOX or β-aminoproprionitrile (βAPN), an inhibitor of LOX activity, that attenuates LOX activity, downregulates HIF-1α protein expression and inhibits HO8910 migratory and invasive abilities. LOX catalytic activity is significantly reduced under hypoxic conditions. Moreover, EOC cells display a marked increase in LOX-dependent FAK/AKT activation and cell migration following hypoxia/reoxygenation. Collectively, our study demonstrates that the hypoxia-HIF-1α, LOX-FAK/AKT pathway regulates the migration and invasion of epithelial ovarian cancer cells under hypoxia/reoxygenation conditions, thus, promoting metastasis of ovarian cancer.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Carcinoma, Ovarian Epithelial
  • Cell Hypoxia / genetics
  • Cell Line, Tumor
  • Cell Movement
  • Female
  • Focal Adhesion Kinase 1 / metabolism
  • Gene Expression Regulation, Neoplastic
  • Humans
  • Hypoxia-Inducible Factor 1, alpha Subunit / genetics*
  • Hypoxia-Inducible Factor 1, alpha Subunit / metabolism
  • Middle Aged
  • Neoplasm Invasiveness / genetics*
  • Neoplasm Metastasis / genetics
  • Neoplasm Staging
  • Neoplasms, Glandular and Epithelial / genetics*
  • Neoplasms, Glandular and Epithelial / pathology
  • Ovarian Neoplasms / genetics*
  • Ovarian Neoplasms / pathology
  • Protein-Lysine 6-Oxidase / genetics*
  • Protein-Lysine 6-Oxidase / metabolism
  • Proto-Oncogene Proteins c-akt / metabolism

Substances

  • Hypoxia-Inducible Factor 1, alpha Subunit
  • Protein-Lysine 6-Oxidase
  • Focal Adhesion Kinase 1
  • PTK2 protein, human
  • Proto-Oncogene Proteins c-akt