Early-response gene signalling is induced by angiogenic oligosaccharides of hyaluronan in endothelial cells. Inhibition by non-angiogenic, high-molecular-weight hyaluronan.
The degradation products of hyaluronan are known to stimulate endothelial-cell proliferation and to promote neovascularization associated with angiogenesis, whilst native high-molecular-weight hyaluronan is inhibitory to these processes. To investigate the cellular signalling pathways coupled to hyaluronan-induced responses in angiogenesis, we have analyzed early-response gene expression in vitro, in cultured bovine aortic endothelial cells. Angiogenic oligosaccharides of hyaluronan induced rapid transient up-regulation of the immediate early genes c-fos, c-jun, jun-B, Krox-20 and Krox-24. In contrast, native hyaluronan when used alone failed to elicit a significant change in expression of any of the genes tested, and when used in combination with angiogenic oligosaccharides of hyaluronan, gave a dose-dependent inhibition of induced gene expression. However, prior addition of angiogenic hyaluronan, as little as one minute before addition of high-molecular-weight hyaluronan, abrogated this inhibition, suggesting that positive or negative responses associated with hyaluronan signalling are integrated at a very early stage following receptor binding. Conversely, prior addition of high-molecular-weight hyaluronan led to an irreversible block in gene expression and proliferative response. These data are consistent with native hyaluronan antagonizing the angiogenic response in part by blocking a signalling cascade at or immediately following ligand-receptor interaction. Finally, we demonstrated that chronic exposure to oligosaccharides of hyaluronan is essential for cell proliferation, indicating that short-term immediate early-gene signalling is insufficient to elicit the proliferation of endothelial cells.
Deed
R
R
Paterson Institute for Cancer Research, Manchester, UK.
Rooney
P
P
Kumar
P
P
Norton
J D
JD
Smith
J
J
Freemont
A J
AJ
Kumar
S
S
D000818:Animals; D002417:Cattle; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D004268:DNA-Binding Proteins / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D051767:Early Growth Response Protein 2; D004730:Endothelium, Vascular / Q000187:drug effects / Q000378:metabolism*; D005786:Gene Expression Regulation; D018960:Hyaluronan Receptors / Q000378:metabolism; D006820:Hyaluronic Acid / Q000494:pharmacology*; D017874:Immediate-Early Proteins / Q000378:metabolism*; D007150:Immunohistochemistry; D018919:Neovascularization, Physiologic / Q000187:drug effects; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism; D015854:Up-Regulation
D004268:DNA-Binding Proteins; D051767:Early Growth Response Protein 2; D018960:Hyaluronan Receptors; D017874:Immediate-Early Proteins; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D014157:Transcription Factors; D006820:Hyaluronic Acid