Targeted inhibition of p38alpha MAPK suppresses tumor-associated endothelial cell migration in response to hypericin-based photodynamic therapy

Biochem Biophys Res Commun. 2005 Nov 25;337(3):928-35. doi: 10.1016/j.bbrc.2005.09.135. Epub 2005 Sep 30.

Abstract

Photodynamic therapy (PDT) is an established anticancer modality and hypericin is a promising photosensitizer for the treatment of bladder tumors. We show that exposure of bladder cancer cells to hypericin PDT leads to a rapid rise in the cytosolic calcium concentration which is followed by the generation of arachidonic acid by phospholipase A2 (PLA2). PLA2 inhibition significantly protects cells from the PDT-induced intrinsic apoptosis and attenuates the activation of p38 MAPK, a survival signal mediating the up-regulation of cyclooxygenase-2 that converts arachidonic acid into prostanoids. Importantly, inhibition of p38alpha MAPK blocks the release of vascular endothelial growth factor and suppresses tumor-promoted endothelial cell migration, a key step in angiogenesis. Hence, targeted inhibition of p38alpha MAPK could be therapeutically beneficial to PDT, since it would prevent COX-2 expression, the inducible release of growth and angiogenic factors by the cancer cells, and cause an increase in the levels of free arachidonic acid, which promotes apoptosis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anthracenes
  • Cell Line
  • Cell Movement / drug effects*
  • Drug Delivery Systems / methods
  • Endothelial Cells / drug effects
  • Endothelial Cells / enzymology*
  • Endothelial Cells / pathology
  • Enzyme Inhibitors / administration & dosage
  • HeLa Cells
  • Humans
  • Mitogen-Activated Protein Kinase 14 / antagonists & inhibitors*
  • Mitogen-Activated Protein Kinase 14 / metabolism*
  • Neovascularization, Pathologic / enzymology*
  • Neovascularization, Pathologic / pathology*
  • Neovascularization, Pathologic / prevention & control
  • Perylene / analogs & derivatives
  • Photochemotherapy / methods*
  • Photosensitizing Agents / administration & dosage
  • Protein Kinase C / antagonists & inhibitors
  • Signal Transduction / drug effects

Substances

  • Anthracenes
  • Enzyme Inhibitors
  • Photosensitizing Agents
  • Perylene
  • hypericin
  • Protein Kinase C
  • Mitogen-Activated Protein Kinase 14