The VEGF pathway and the AKT/mTOR/p70S6K1 signalling pathway in human epithelial ovarian cancer

Br J Cancer. 2009 Mar 24;100(6):971-8. doi: 10.1038/sj.bjc.6604921. Epub 2009 Feb 24.

Abstract

Vascular endothelial growth factor (VEGF)-A inhibitors exhibit unseen high responses and toxicity in recurrent epithelial ovarian cancer suggesting an important role for the VEGF/VEGFR pathway. We studied the correlation of VEGF signalling and AKT/mTOR signalling. Using a tissue microarray of clinical samples (N=86), tumour cell immunohistochemical staining of AKT/mTOR downstream targets, pS6 and p4E-BP1, together with tumour cell staining of VEGF-A and pVEGFR2 were semi-quantified. A correlation was found between the marker for VEGFR2 activation (pVEGFR2) and a downstream target of AKT/mTOR signalling (pS6) (R=0.29; P=0.002). Additional gene expression analysis in an independent cDNA microarray dataset (N=24) showed a negative correlation (R=-0.73, P<0.0001) between the RPS6 and the VEGFR2 gene, which is consistent as the gene expression and phosphorylation of S6 is inversely regulated. An activated tumour cell VEGFR2/AKT/mTOR pathway was associated with increased incidence of ascites (chi(2), P=0.002) and reduced overall survival of cisplatin-taxane-based patients with serous histology (N=32, log-rank test, P=0.04). These data propose that VEGF-A signalling acts on tumour cells as a stimulator of the AKT/mTOR pathway. Although VEGF-A inhibitors are classified as anti-angiogenic drugs, these data suggest that the working mechanism has an important additional modality of targeting the tumour cells directly.

MeSH terms

  • Adult
  • Aged
  • Aged, 80 and over
  • Angiogenesis Inhibitors / pharmacology
  • Angiogenesis Inhibitors / therapeutic use
  • Female
  • Humans
  • Immunohistochemistry
  • Middle Aged
  • Neoplasms, Glandular and Epithelial / drug therapy*
  • Neoplasms, Glandular and Epithelial / physiopathology
  • Ovarian Neoplasms / drug therapy*
  • Ovarian Neoplasms / physiopathology
  • Protein Kinases / physiology*
  • Proto-Oncogene Proteins c-akt / physiology*
  • Ribosomal Protein S6 Kinases, 70-kDa / analysis
  • Ribosomal Protein S6 Kinases, 70-kDa / genetics
  • Ribosomal Protein S6 Kinases, 70-kDa / physiology*
  • Signal Transduction / physiology*
  • TOR Serine-Threonine Kinases
  • Tissue Array Analysis
  • Vascular Endothelial Growth Factor A / analysis
  • Vascular Endothelial Growth Factor A / antagonists & inhibitors
  • Vascular Endothelial Growth Factor A / physiology*
  • Vascular Endothelial Growth Factor Receptor-2 / analysis
  • Vascular Endothelial Growth Factor Receptor-2 / genetics
  • Vascular Endothelial Growth Factor Receptor-2 / physiology

Substances

  • Angiogenesis Inhibitors
  • VEGFA protein, human
  • Vascular Endothelial Growth Factor A
  • Protein Kinases
  • MTOR protein, human
  • Vascular Endothelial Growth Factor Receptor-2
  • Proto-Oncogene Proteins c-akt
  • Ribosomal Protein S6 Kinases, 70-kDa
  • TOR Serine-Threonine Kinases