title: Paclitaxel and cyclosporine A show supra-additive antiproliferative effects on smooth muscle cells by activation of protein kinase C.
abstract: We intended to establish a pharmacologic concept of synergistic antiproliferative effects on smooth muscle cells (SMC) by using paclitaxel and cyclosporine A at clinically applicable doses. Coronary SMC were incubated with paclitaxel and cyclosporine A at concentrations of 10-20 nmol/L and 83-415 nmol/L, respectively. Antiproliferative effects were assessed by cell counts, [3H]thymidine incorporation and cell cycle analysis. In addition, apoptosis was studied by cytoplasmic histone-associated DNA fragments and in vitro protein kinase C activity (PKC) was determined by immunoassay. We found paclitaxel and cyclosporine A to exert a highly supra-additive antiproliferative effect on SMC with significant reductions of cell counts (p < 0.01) and [3H]thymidine incorporation (p < 0.05). SMC were found to be arrested at the G2/M transition. This antiproliferative effect was observed in the absence of DNA fragmentation above values obtained for single compound treatment, which had virtually no impact on cell proliferation. DNA fragmentation started to increase at a drug combination comprising paclitaxel at the higher dose of 20 nmol/L. Under the treatment with both paclitaxel and cyclosporine A, PKC activity showed a 1.8-fold increase (p < 0.05) compared with untreated controls. In conclusion, PKC mediates supra-additive antiproliferative effects of paclitaxel and cyclosporine A on SMC. The data demonstrate a highly efficient pharmacologic concept for the inhibition of SMC proliferation. Further studies are needed to test this concept under in vivo conditions for the prevention of restenosis or transplant vasculopathy by systemic application of cyclosporine A--when already applied for immunosuppressive purposes--and local delivery of paclitaxel.
authors: Institute for Arteriosclerosis Research and Department of Cardiology and Angiology, University of Münster, Germany. sinderm@uni-muenster.de
authors: Jürgen R
authors: JR
authors: Sindermann
authors: Adriane
authors: A
authors: Skaletz-Rorowski
authors: Anke
authors: A
authors: Bartels
authors: Helge
authors: H
authors: Hohage
authors: Gabriele
authors: G
authors: Plenz
authors: Annette
authors: A
authors: Schmidt
authors: Günter
authors: G
authors: Breithardt
mesh_terms: D020533:Angiogenesis Inhibitors / Q000494:pharmacology*; D000818:Animals; D017209:Apoptosis / Q000187:drug effects; D002417:Cattle; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D003324:Coronary Artery Disease / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D023903:Coronary Restenosis / Q000188:drug therapy / Q000378:metabolism / Q000473:pathology; D003331:Coronary Vessels / Q000166:cytology; D016572:Cyclosporine / Q000494:pharmacology*; D004789:Enzyme Activation / Q000187:drug effects; D007166:Immunosuppressive Agents / Q000494:pharmacology*; D009131:Muscle, Smooth, Vascular / Q000166:cytology* / Q000187:drug effects / Q000201:enzymology; D017239:Paclitaxel / Q000494:pharmacology*; D011493:Protein Kinase C / Q000378:metabolism*
chemical_list: D020533:Angiogenesis Inhibitors; D007166:Immunosuppressive Agents; D016572:Cyclosporine; D011493:Protein Kinase C; D017239:Paclitaxel