EphA2-induced angiogenesis in ewing sarcoma cells works through bFGF production and is dependent on caveolin-1

PLoS One. 2013 Aug 12;8(8):e71449. doi: 10.1371/journal.pone.0071449. eCollection 2013.

Abstract

Angiogenesis is the result of the combined activity of the tumor microenvironment and signaling molecules. The angiogenic switch is represented as an imbalance between pro- and anti-angiogenic factors and is a rate-limiting step in the development of tumors. Eph receptor tyrosine kinases and their membrane-anchored ligands, known as ephrins, constitute the largest receptor tyrosine kinase (RTK) subfamily and are considered a major family of pro-angiogenic RTKs. Ewing sarcoma (EWS) is a highly aggressive bone and soft tissue tumor affecting children and young adults. As other solid tumors, EWS are reliant on a functional vascular network for the delivery of nutrients and oxygen and for the removal of waste. Based on the biological roles of EphA2 in promoting angiogenesis, we explored the functional role of this receptor and its relationship with caveolin-1 (CAV1) in EWS angiogenesis. We demonstrated that lack of CAV1 results in a significant reduction in micro vascular density (MVD) on 3 different in vivo models. In vitro, this phenomenon correlated with inactivation of EphA2 receptor, lack of AKT response and downregulation of bFGF. We also demonstrated that secreted bFGF from EWS cells acted as chemoattractant for endothelial cells. Furthermore, interaction between EphA2 and CAV1 was necessary for the right localization and signaling of the receptor to produce bFGF through AKT and promote migration of endothelial cells. Finally, introduction of a dominant-negative form of EphA2 into EWS cells mostly reproduced the effects occurred by CAV1 silencing, strongly suggesting that the axis EphA2-CAV1 participates in the promotion of endothelial cell migration toward the tumors favoring EWS angiogenesis.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bone Neoplasms / genetics
  • Bone Neoplasms / metabolism*
  • Bone Neoplasms / pathology*
  • Caveolin 1 / genetics
  • Caveolin 1 / metabolism*
  • Cell Line, Tumor
  • Cell Movement / genetics
  • Disease Models, Animal
  • Endothelial Cells / metabolism
  • Female
  • Fibroblast Growth Factor 2 / biosynthesis*
  • Fibroblast Growth Factor 2 / genetics
  • Gene Silencing
  • Heterografts
  • Humans
  • Mice
  • Mice, Knockout
  • Neovascularization, Pathologic / genetics
  • Neovascularization, Pathologic / metabolism*
  • Protein Binding
  • Protein Transport
  • Proto-Oncogene Proteins c-akt / metabolism
  • Receptor, EphA2 / genetics
  • Receptor, EphA2 / metabolism*
  • Sarcoma, Ewing / genetics
  • Sarcoma, Ewing / metabolism*
  • Sarcoma, Ewing / pathology*
  • Signal Transduction
  • Transcription, Genetic
  • Tumor Burden / genetics

Substances

  • Caveolin 1
  • Fibroblast Growth Factor 2
  • Receptor, EphA2
  • Proto-Oncogene Proteins c-akt

Grants and funding

This work was funded by the Fondo de Investigaciones Sanitarias-ISCIII-FEDER (CP06/00151; PI080259; PI110038; PI110018; RD09/0076/00028; RD06/0020/0059; RD06/0020/1038). LLT is funded by the Comissionat per a Universitats i Recerca (CUR) from Departament d’Innovació, Universitats i Empresa (DIUE) de la Generalitat de Catalunya i del Fons Social Europeu. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.