Chronic treatment with PDGF-BB and endothelin-1 synergistically induces vascular hyperplasia and loss of contractility in organ-cultured rat tail artery.
OBJECTIVE
In this study, we examined the synergistic effects of the two potent pathogenic factors, platelet-derived growth factor-BB (PDGF-BB) and endothelin-1 (ET-1) to induce vascular hyperplasia using ex vivo organ-culture system.


RESULTS
In organ-cultured rat tail arteries, concomitant treatment with 100 ng/ml PDGF-BB and 300 nM ET-1 for 4 days induced medial hyperplasia with increased smooth muscle cell proliferation. Concomitant treatment with PDGF-BB (10-300 nM) and ET-1 (30 nM-1 μM) dose-dependently suppressed contractile responses to high K(+) and norepinephrine. This dyscontractility was accompanied by decreased α-actin protein expression. In all series of experiments, concomitant treatment with PDGF-BB and ET-1 exhibited stronger effects than sole treatment with PDGF-BB (100 ng/ml) or ET-1 (300 nM). Western blot analysis revealed that concomitant treatment with PDGF-BB and ET-1 synergistically phosphorylated extracellular signal-regulated kinase 1 and 2 (ERK1/2), Akt, and a downstream target of mammalian target of rapamycin (mTOR), p70 ribosomal S6 kinase in cultured artery. Consistently, a MAPK/ERK kinase (MEK) inhibitor, PD98059 (30 μM), a phosphoinositide 3-kinase (PI3K) inhibitor, LY294002, and an mTOR inhibitor, rapamycin (30 nM), partially restored PDGF-BB and ET-1-induced hyperplastic changes.


CONCLUSIONS
We evidenced for the first time at tissue level that PDGF-BB and ET-1 synergistically accelerate vascular smooth muscle hyperplastic changes and lose its contractility, at least partially through ERK1/2, Akt, and mTOR activation.
Department of Veterinary Pharmacology, Graduate School of Agriculture and Life Sciences, The University of Tokyo, 1-1-1 Yayoi, Bunkyo-ku, Tokyo 113-8657, Japan.
Taiki
T
Kida
Hiroko
H
Chuma
Takahisa
T
Murata
Hideyuki
H
Yamawaki
Shigeko
S
Matsumoto
Masatoshi
M
Hori
Hiroshi
H
Ozaki
D000818:Animals; D001158:Arteries / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D000077214:Becaplermin; D015153:Blotting, Western; D049109:Cell Proliferation / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D019332:Endothelin-1 / Q000494:pharmacology*; D006801:Humans; D006965:Hyperplasia; D007150:Immunohistochemistry; D008297:Male; D019950:Mitogen-Activated Protein Kinase 1 / Q000037:antagonists & inhibitors / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000037:antagonists & inhibitors / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D032389:Myocytes, Smooth Muscle / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology; D009924:Organ Culture Techniques; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010766:Phosphorylation; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors / Q000378:metabolism; D020574:Proto-Oncogene Proteins c-sis; D051381:Rats; D017207:Rats, Sprague-Dawley; D011994:Recombinant Proteins / Q000494:pharmacology; D038762:Ribosomal Protein S6 Kinases, 70-kDa / Q000037:antagonists & inhibitors / Q000378:metabolism; D058570:TOR Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D013623:Tail / Q000098:blood supply*; D013997:Time Factors; D014661:Vasoconstriction / Q000187:drug effects*; D014662:Vasoconstrictor Agents / Q000494:pharmacology
D000077214:Becaplermin; D019332:Endothelin-1; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D019869:Phosphatidylinositol 3-Kinases; D000081082:Phosphoinositide-3 Kinase Inhibitors; D010982:Platelet-Derived Growth Factor; D047428:Protein Kinase Inhibitors; D051057:Proto-Oncogene Proteins c-akt; D020574:Proto-Oncogene Proteins c-sis; D011994:Recombinant Proteins; D038762:Ribosomal Protein S6 Kinases, 70-kDa; D058570:TOR Serine-Threonine Kinases; D014662:Vasoconstrictor Agents; C546845:mTOR protein, rat