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Impact of VEGF‐dependent tumour micro‐environment on EDB fibronectin expression by subcutaneous human tumour xenografts in nude mice
Author(s) -
Coltrini Daniela,
Ronca Roberto,
Belleri Mirella,
Zardi Luciano,
Indraccolo Stefano,
Scarlato Valentina,
Giavazzi Raffaella,
Presta Marco
Publication year - 2009
Publication title -
the journal of pathology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.964
H-Index - 184
eISSN - 1096-9896
pISSN - 0022-3417
DOI - 10.1002/path.2626
Subject(s) - cancer research , fibronectin , biology , angiogenesis , microbiology and biotechnology , extracellular matrix , transfection , vascular endothelial growth factor , nude mouse , cell culture , vegf receptors , genetics
Fibronectin (FN) is an extracellular matrix cell‐adhesive glycoprotein. The alternative spliced isoform EDB‐FN (extra domain B containing FN) is highly expressed in tumour blood vessels and stroma and represents a candidate for tumour targeting. To investigate the impact of different angiogenic micro‐environments on EDB‐FN expression, we used a tumour model in which human endometrial adenocarcinoma Tet‐FGF2 cells overexpressing fibroblast growth factor‐2 (FGF2) driven by the tetracycline‐responsive promoter were further transfected with a VEGF antisense cDNA, generating AS‐VEGF/Tet‐FGF2 cells. In this model, the expression of FGF2 plus VEGF results in fast‐growing, highly vascularized Tet‐FGF2 tumours. Down‐regulation of FGF2 production by tetracycline administration and/or of VEGF production by AS‐VEGF transduction inhibited tumour growth and vascularization, with profound changes in tumour micro‐environment. Quantitative RT‐PCR analysis using human EDB‐FN primers shows that subcutaneous grafting in immunodeficient mice is per se sufficient to cause a dramatic up‐regulation of EDB‐FN expression by these cells, as well as by human oesophageal cancer KYSE 30 cells and renal carcinoma Caki‐1 cells. However, in vivo down‐regulation of VEGF expression, as occurs in AS‐VEGF/Tet‐FGF2 tumours, and to a lesser extent of FGF2 expression, as occurs in tetracycline‐treated Tet‐FGF2 tumour‐bearing animals, causes significant inhibition of EDB‐FN production in tumour grafts, as shown by immunohistochemistry and quantitative RT‐PCR analysis. Accordingly, treatment of Tet‐FGF2 tumour‐bearing animals with the neutralizing anti‐murine VEGF receptor‐2 antibody DC101, or of Caki‐1 tumour‐bearing animals with the anti‐VEGF antibody bevacizumab, inhibited EDB‐FN expression in tumour grafts. EDB‐FN down‐regulation was paralleled by a decrease in vascularity, thus confirming EDB‐FN as a marker of tumour angiogenesis. These data demonstrate that the angiogenic micro‐environment, and in particular the VEGF/VEGFR‐2 system, plays a key role in modulating EDB‐FN expression by tumour cells in vivo . This may have implications for the design of therapeutic strategies targeting EDB‐FN in combination with anti‐angiogenic and/or cytotoxic drugs. Copyright © 2009 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.