HGF regulates VEGF expression via the c-Met receptor downstream pathways, PI3K/Akt, MAPK and STAT3, in CT26 murine cells

Int J Oncol. 2013 Feb;42(2):535-42. doi: 10.3892/ijo.2012.1728. Epub 2012 Dec 6.

Abstract

In the present study, we assessed the involvement of hepatocyte growth factor (HGF)/c-Met signalling with vascular endothelial cell growth factor (VEGF) and hypoxia inducible factor (HIF)-1α expression in the downstream pathways phosphatidylinositol 3-kinase (PI3K)/Akt, mitogen-activated protein kinase (MAPK) and signal transducer and activator of transcription 3 (STAT3) in CT26 cells, to determine the mechanisms of the potent anti-angiogenic effect of NK4. We established genetically modified CT26 cells to produce NK4 (CT26-NK4). VEGF expression in subcutaneous CT26 tumours in vivo and in culture supernatants in vitro was determined by ELISA. HIF-1α expression in nuclear extracts was evaluated by western blot analysis. VEGF and HIF-1α mRNA levels were examined by real-time reverse transcription-polymerase chain reaction (RT-PCR). The DNA binding activity of HIF-1α was evaluated using an HIF-1α transcription factor assay kit. Our results demonstrated that VEGF expression was reduced in homografts of CT26-NK4 cells, compared to those of the control cells. In vitro, VEGF expression, which was induced by HGF, was inhibited by anti-HGF antibody, NK4 and by kinase inhibitors (PI3K, LY294002; MAPK, PD98059; and STAT3, Stattic). HGF‑induced HIF‑1α transcriptional activity was also inhibited by the kinase inhibitors. Real-time RT-PCR demonstrated that HGF‑induced HIF‑1α mRNA expression was not inhibited by LY294002 and PD98059, but was inhibited by Stattic. These data suggest that the PI3K/Akt, MAPK and STAT3 pathways, downstream of HGF/c‑Met signalling, are involved in the regulation of VEGF expression in CT26 cells. HGF/c‑Met signalling may be a promising target for anti-angiogenic strategies.

MeSH terms

  • Adenocarcinoma / drug therapy
  • Adenocarcinoma / genetics*
  • Adenocarcinoma / pathology
  • Animals
  • Colonic Neoplasms / drug therapy
  • Colonic Neoplasms / genetics*
  • Colonic Neoplasms / pathology
  • Gene Expression Regulation, Neoplastic
  • Hepatocyte Growth Factor / biosynthesis*
  • Hepatocyte Growth Factor / genetics
  • Hepatocyte Growth Factor / metabolism
  • Humans
  • Hypoxia-Inducible Factor 1, alpha Subunit / genetics
  • MAP Kinase Signaling System / genetics
  • Mice
  • Molecular Targeted Therapy
  • Oncogene Protein v-akt / genetics
  • Oncogene Protein v-akt / metabolism
  • Phosphatidylinositol 3-Kinases / genetics
  • Phosphatidylinositol 3-Kinases / metabolism
  • Proto-Oncogene Proteins c-met / biosynthesis*
  • Proto-Oncogene Proteins c-met / genetics
  • Proto-Oncogene Proteins c-met / metabolism
  • STAT3 Transcription Factor / metabolism
  • Vascular Endothelial Growth Factor A / biosynthesis*
  • Vascular Endothelial Growth Factor A / genetics
  • Vascular Endothelial Growth Factor A / metabolism

Substances

  • HGF protein, mouse
  • Hypoxia-Inducible Factor 1, alpha Subunit
  • STAT3 Transcription Factor
  • Stat3 protein, mouse
  • Vascular Endothelial Growth Factor A
  • vascular endothelial growth factor A, mouse
  • Hepatocyte Growth Factor
  • Phosphatidylinositol 3-Kinases
  • Proto-Oncogene Proteins c-met
  • Oncogene Protein v-akt