Promoter methylation status of VEGF receptor genes: a possible epigenetic biomarker to anticipate the efficacy of intracellular-acting VEGF-targeted drugs in cancer cells

Epigenetics. 2012 Feb;7(2):191-200. doi: 10.4161/epi.7.2.18973.

Abstract

We evaluated whether the inhibitory effects of vascular endothelial growth factor (VEGF)-targeted drugs on the proliferation of cancer cells differed according to VEGF receptor (VEGFR) genes, Flt1 and KDR, promoter methylation status. Five hyper-VEGFR-methylation and six no-VEGFR-methylation cancer cells were used for the present study, together with human umbilical endothelial cells (HUVECs) as a control. No-VEGFR-methylation cancer cells showed higher expression of Flt1 and KDR than hyper-VEGFR-methylation cancer cells. Hyper-VEGFR-methylation cancer cells only showed increased expression and protein levels of Flt1 and KDR after treatment with the demethylase 5-aza-2'-deoxycytidine. Two drugs (a VEGF-specific-antibody, bevacizumab, and a KDR-specific-antibody) targeting extracellular VEGF-VEGFR signaling and two VEGF-specific-tyrosine kinase inhibitors (PTK/ZK and sunitinib) targeting intracellular VEGFR signaling were used in the cell proliferation assay. HUVECs showed dose- and time-dependent proliferation decrease with all tested drugs over a 72 h incubation period. No- or hyper-VEGFR-methylation cancer cells showed no significant proliferation differences after treatment with VEGF-specific-antibody or VEGFR2-specific-antibody. After PTK/ZK or sunitinib treatment, no-VEGFR-methylation cancer cells showed dose- or time-dependent decreases in proliferation. Hyper-VEGFR-methylation cancer cells also showed proliferation inhibition by VEGF-specific-tyrosine kinase inhibitors after demethylation of Flt1 and KDR. Proliferation inhibition synergistically increased after combination of demethylation with PTK/ZK in hyper-VEGF-methylation cancer cells. We observed that intracellular targeting of VEGF-VEGFR signaling could be more effective than extracellular targeting of the pathway in the suppression of proliferation of some cancer cells. In particular, the efficacy of intracellular targeting of VEGF-specific-tyrosine kinase inhibitors might be influenced by the epigenetic alteration of VEGFRs.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antineoplastic Agents / pharmacology
  • Antineoplastic Agents / therapeutic use
  • Biomarkers, Tumor / genetics*
  • Cell Line, Tumor
  • Cell Proliferation / drug effects
  • CpG Islands / genetics
  • DNA Methylation / drug effects
  • DNA Methylation / genetics*
  • Epigenesis, Genetic* / drug effects
  • Extracellular Signal-Regulated MAP Kinases / metabolism
  • Human Umbilical Vein Endothelial Cells / metabolism
  • Humans
  • Intracellular Space / drug effects
  • Intracellular Space / metabolism
  • Molecular Targeted Therapy
  • Neoplasms / drug therapy*
  • Neoplasms / enzymology
  • Neoplasms / genetics
  • Neoplasms / pathology
  • Phosphorylation / drug effects
  • Promoter Regions, Genetic / genetics*
  • Protein Kinase Inhibitors / pharmacology
  • Protein Kinase Inhibitors / therapeutic use
  • Proto-Oncogene Proteins c-akt / metabolism
  • Receptors, Vascular Endothelial Growth Factor / genetics*
  • Treatment Outcome
  • Vascular Endothelial Growth Factor A / antagonists & inhibitors*
  • Vascular Endothelial Growth Factor A / metabolism

Substances

  • Antineoplastic Agents
  • Biomarkers, Tumor
  • Protein Kinase Inhibitors
  • Vascular Endothelial Growth Factor A
  • Receptors, Vascular Endothelial Growth Factor
  • Proto-Oncogene Proteins c-akt
  • Extracellular Signal-Regulated MAP Kinases