Effect of p27 deficiency and rapamycin on intimal hyperplasia: in vivo and in vitro studies using a p27 knockout mouse model.
Rapamycin, an immunosuppressant and antiproliferative agent, reduces intimal hyperplasia after arterial injury in animal models and in a preliminary study in humans. Rapamycin treatment reportedly increases expression of p27, a cyclin-dependent kinase inhibitor. This mechanism was tested using a p27-deficient (p27 -/-) murine model. Aortic smooth muscle cells from wild-type (WT) and p27 -/- mice were isolated and cultured. Cell proliferation, assessed by cell count and (3)H-thymidine incorporation, was inhibited significantly by rapamycin in WT and p27 -/- cells at concentrations of 1 ng/ml, 10 ng/ml, and 100 ng/ml (p < 0.05, versus control). The in vivo effect on intimal hyperplasia was studied in p27 -/- and WT mice after femoral artery transluminal injury. Rapamycin treatment was started 2 days before injury and maintained for 2 weeks (1 mg/kg per 48 hours, ip). No significant differences in intima-to-media ratio were found between WT (1.1 +/- 0.1) and p27 -/- mice (1.0 +/- 0.1) 4 weeks after injury. Rapamycin significantly (p < 0.05) reduced intima-to-media ratios in both WT (0.7 +/- 0.1) and p27 -/- mice (0.5 +/- 0.1), compared with untreated mice. p27 deficiency did not alter the arterial wall proliferative response to injury. The inhibitory effect of rapamycin on intimal hyperplasia occurred via a p27-independent mechanism. The in vitro data showed that this effect was mediated through decreased proliferation and enhanced apoptosis.
Roqué
M
M
Cardiovascular Biology Research Laboratories, Mount Sinai School of Medicine, New York City, New York 10029-6574, USA.
Reis
E D
ED
Cordon-Cardo
C
C
Taubman
M B
MB
Fallon
J T
JT
Fuster
V
V
Badimon
J J
JJ
D000818:Animals; D001011:Aorta / Q000187:drug effects / Q000293:injuries / Q000473:pathology*; D017209:Apoptosis / Q000187:drug effects; D018797:Cell Cycle Proteins; D002455:Cell Division / Q000187:drug effects; D050760:Cyclin-Dependent Kinase Inhibitor p27; D005260:Female; D017353:Gene Deletion; D006965:Hyperplasia; D007166:Immunosuppressive Agents / Q000494:pharmacology*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout / Q000235:genetics; D008869:Microtubule-Associated Proteins / Q000172:deficiency* / Q000235:genetics; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects; D020123:Sirolimus / Q000494:pharmacology*; D025521:Tumor Suppressor Proteins; D017539:Tunica Intima / Q000187:drug effects / Q000293:injuries / Q000473:pathology*; D014949:Wounds, Nonpenetrating / Q000378:metabolism / Q000473:pathology
C493961:Cdkn1b protein, mouse; D018797:Cell Cycle Proteins; D007166:Immunosuppressive Agents; D008869:Microtubule-Associated Proteins; D025521:Tumor Suppressor Proteins; D050760:Cyclin-Dependent Kinase Inhibitor p27; D020123:Sirolimus