VEGFR1 and PKCα signaling control melanoma vasculogenic mimicry in a VEGFR2 kinase-independent manner

Melanoma Res. 2011 Apr;21(2):91-8. doi: 10.1097/CMR.0b013e328343a237.

Abstract

We have recently shown that vascular endothelial growth factor-A (VEGFA), a major regulator of tumor vascularization, is essential for the organization of tumor cells into capillary-like structure (CLS), which is a hallmark of tumor vasculogenic mimicry (VM). Herein we further dissect the involvement of VEGFA and its downstream transducers, VEGF receptor 1 (VEGFR1), VEGFR2, and protein kinase C (PKC) in melanoma VM. The knockdown of VEGFR1 in three melanoma cell lines completely disrupts Matrigel-induced CLS formation, whereas inhibition of VEGFR2 kinase with a specific inhibitor, protein tyrosine kinase inhibitor II (PTKi-II), does not affect the process, indicating that VEGFR2 signaling is not involved in VEGFA-mediated melanoma VM. Furthermore, among tested PKC isoforms, only PKCα and δ are expressed in the melanoma cells during CLS formation. Pretreatment with selective PKCα and δ inhibitors blocked CLS formation. However, inhibition of PKCα, but not PKCδ, completely destroyed the previously formed CLS. Moreover, knockdown of PKCα, but not PKCδ, using small interfering RNAs abrogated CLS formation, suggesting that PKCα is the major contributory factor in melanoma VM. In-vivo experiments indicate that disruption of PKCα signaling significantly reduces the signs of VM in allografted B16/F10 melanoma. These findings may contribute to the development of new therapeutic agents that target melanoma VM.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Line, Tumor
  • Female
  • Humans
  • Indoles / pharmacology
  • Melanoma / blood supply*
  • Melanoma / enzymology
  • Melanoma / pathology
  • Melanoma, Experimental / blood supply
  • Melanoma, Experimental / enzymology
  • Melanoma, Experimental / pathology
  • Mice
  • Mice, Inbred C57BL
  • Neovascularization, Pathologic / enzymology*
  • Neovascularization, Pathologic / pathology
  • Protein Kinase C-alpha / antagonists & inhibitors
  • Protein Kinase C-alpha / metabolism*
  • Pyrroles / pharmacology
  • RNA, Small Interfering / administration & dosage
  • RNA, Small Interfering / genetics
  • Signal Transduction
  • Skin Neoplasms / blood supply*
  • Skin Neoplasms / enzymology
  • Skin Neoplasms / pathology
  • Transfection
  • Vascular Endothelial Growth Factor Receptor-1 / genetics
  • Vascular Endothelial Growth Factor Receptor-1 / metabolism*
  • Vascular Endothelial Growth Factor Receptor-2 / metabolism*

Substances

  • Indoles
  • Pyrroles
  • RNA, Small Interfering
  • Ro 32-0432
  • Vascular Endothelial Growth Factor Receptor-1
  • Vascular Endothelial Growth Factor Receptor-2
  • Protein Kinase C-alpha