The sphingosine kinase inhibitor N,N-dimethylsphingosine inhibits neointimal hyperplasia.
OBJECTIVE
Sphingosine-1-phosphate and its receptors may be involved in vascular smooth muscle cell (VSMC) proliferation following vascular injury. Here, we evaluate the effect of d-erythro-N,N-dimethylsphingosine (DMS), a sphingosine kinase (SK) inhibitor, on VSMC proliferation, apoptosis and neointimal formation.


METHODS
Growth responses in vitro to fetal calf serum (FCS) were measured by [(3)H]-thymidine incorporation and extracellular signal-regulated kinase-1/2 (ERK-1/2) activation in quiescent primary cultures of porcine VSMC in the presence and absence of various concentrations of the SK inhibitor DMS. In vivo treatment with DMS was delivered with a local endoluminal catheter, following balloon injury of coronary arteries. The artery intimal formation was investigated by angiography, myography and histomorphometry.


RESULTS
In vitro experiments indicated that DMS induced a dose-dependent reduction in [(3)H]-thymidine incorporation and ERK-1/2 activation via a protein kinase C (PKC) independent mechanism with an IC(50) value of 12 +/- 6 and 15 +/- 10 microM respectively. DMS also reduced Akt signalling. Four weeks following in vivo delivery of DMS, complete functional endothelial regeneration was observed in all treatment groups, with significant reduction of intimal formation (vehicle 23.7 +/- 4.6% vs. DMS infusion 8.92 +/- 2.9%, P < 0.05).


CONCLUSIONS
Taken together, these results demonstrate that local administration of the SK inhibitor, DMS, reduced neointimal formation, and this effect could involve inhibition of ERK-1/2 and Akt signalling, and modulation of smooth muscle growth.
McDonald
Robert A
RA
Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow G4 0NR, Scotland, UK.
Pyne
Susan
S
Pyne
Nigel J
NJ
Grant
Anne
A
Wainwright
Cherry L
CL
Wadsworth
Roger M
RM
D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002404:Catheterization; D049109:Cell Proliferation / Q000187:drug effects; D006965:Hyperplasia / Q000473:pathology; D008246:Lysophospholipids; D008297:Male; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism / Q000494:pharmacology; D009131:Muscle, Smooth, Vascular / Q000166:cytology* / Q000187:drug effects* / Q000473:pathology; D032389:Myocytes, Smooth Muscle / Q000378:metabolism; D017853:Phosphotransferases (Alcohol Group Acceptor); D011493:Protein Kinase C / Q000378:metabolism / Q000494:pharmacology; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D013110:Sphingosine / Q000031:analogs & derivatives / Q000494:pharmacology*; D034421:Sus scrofa; D017539:Tunica Intima / Q000187:drug effects* / Q000378:metabolism / Q000473:pathology*; D000099157:Sphingosine Kinase
D008246:Lysophospholipids; D048052:Mitogen-Activated Protein Kinase 3; D017853:Phosphotransferases (Alcohol Group Acceptor); D011493:Protein Kinase C; D047428:Protein Kinase Inhibitors; D051057:Proto-Oncogene Proteins c-akt; D013110:Sphingosine; D000099157:Sphingosine Kinase; C060506:sphingosine 1-phosphate; C061800:N,N-dimethylsphingosine