Purpose: Proliferation and extracellular matrix (ECM) accumulation in the vascular smooth muscle cell (VSMC) and glomerular mesangial cell (MC) play key roles in the development and the progression of transplant glomerulosclerosis and chronic allograft nephropathy. Tautomycetin (TMC), a newly developed immunosuppressive agent, induces T-lymphocyte apoptosis through the inhibition of tyrosine kinase and protein phosphatase 1. We examined the effects of TMC on platelet-derived growth factor (PDGF)-induced proliferation and ECM synthesis in cultured VSMCs and MCs of Sprague- Dawley rats, and investigated the molecular mechanisms that are involved.
Methods: Different concentrations of TMC were administered 1 hour before the addition of PDGF 10 ng/mL into the growth-arrested and synchronized cells. Cell proliferation was assessed by methylthiazoletetrazolium (MTT) assay. Caspase-3 cleavage, fibronectin secretion, and the activation of Akt, ERK, and p38 MAPK were assessed by Western blot analysis, respectively.
Results: PDGF 10 ng/ mL increased cell proliferation, fibronectin secretion, and the activation of Akt, ERK, and p38 MAPK in both VSMCs and MCs. In both cultured cells, TMC at above 1 μg/mL significantly reduced basal MTT and increased cleavage caspase-3 in a dose-dependent manner. TMC at 100 ng/mL decreased the PDGF-induced VSMC and MC proliferation without cytotoxicity. However, fibronectin secretion and the activation of Akt, ERK, and p38 MAPK were not affected at this low concentration of TMC, respectively.
Conclusion: The present data demonstrated that low-dose TMC reduced PDGF-induced VSMC and MC proliferation without affecting the fibronectin secretion and cellular kinase activation. (J Korean Soc Transplant 2005;19:8-13)
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