title: Differential effects of imatinib on PDGF-induced proliferation and PDGF receptor signaling in human arterial and venous smooth muscle cells.
abstract: Platelet-derived growth factor (PDGF) has been implicated in smooth muscle cell (SMC) proliferation, a key event in the development of myointimal hyperplasia in vascular grafts. Recent evidence suggests that the PDGF receptor (PDGFR) tyrosine kinase inhibitor, imatinib, can prevent arterial proliferative diseases. Because hyperplasia is far more common at the venous anastomosis than the arterial anastomosis in vascular grafts, we investigated whether imatinib also inhibited venous SMC (VSMC) proliferation, and examined possible differences in its mechanism of action between VSMC and arterial SMC (ASMC). Human ASMC and VSMC were stimulated with PDGF-AB, in the presence or absence of imatinib (0.1-10 microM). Proliferation was assayed using the 5-bromo-2'-deoxyuridine (BrdU) incorporation assay, while PDGFR, Akt and ERK1/2-mitogen activated protein kinase (MAPK) signaling pathways were investigated by immunoblotting. The proliferative response to PDGF at 50 and 100 ng/ml was 32 and 43% greater, respectively, in VSMC than in ASMC. Similarly, PDGF-stimulated proliferation was more sensitive to inhibition by imatinib in VSMC than ASMC (IC(50) = 0.05 microM vs. 0.4 microM; P < 0.01). Imatinib also more effectively inhibited PDGF-induced phosphorylation of PDGFRbeta and Akt in VSMC, compared to ASMC. These data highlight inherent pharmacodynamic differences between VSMC and ASMC in receptor and cell signaling functions and suggest that imatinib therapy may be useful for the prevention of venous stenosis in vascular grafts.
authors.affiliation: Department of Medicine, University of Utah, 85 North Medical Drive East, Salt Lake City, UT 84112, USA.
authors.forename: Li
authors.initials: L
authors.lastname: Li
authors.forename: Donald K
authors.initials: DK
authors.lastname: Blumenthal
authors.forename: Takahisa
authors.initials: T
authors.lastname: Masaki
authors.forename: Christi M
authors.initials: CM
authors.lastname: Terry
authors.forename: Alfred K
authors.initials: AK
authors.lastname: Cheung
mesh_terms: D001158:Arteries / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D001549:Benzamides; D015153:Blotting, Western; D002453:Cell Cycle / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects*; D002478:Cells, Cultured; D005434:Flow Cytometry; D006801:Humans; D000068877:Imatinib Mesylate; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D010766:Phosphorylation; D010879:Piperazines / Q000494:pharmacology*; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology*; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D011743:Pyrimidines / Q000494:pharmacology*; D017479:Receptors, Platelet-Derived Growth Factor / Q000378:metabolism*; D014680:Veins / Q000166:cytology / Q000187:drug effects / Q000378:metabolism
chemical_list: D001549:Benzamides; D010879:Piperazines; D010982:Platelet-Derived Growth Factor; D011743:Pyrimidines; D000068877:Imatinib Mesylate; D017479:Receptors, Platelet-Derived Growth Factor; D051057:Proto-Oncogene Proteins c-akt; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3