Purpose : Vascular smooth muscle cells (VSMCs) migration and proliferation play important roles in chronic allograft rejection. Mycophenolic acid (MPA) inhibits the proliferation of VSMCs, glomerular mesangial cells and fibroblasts as well
as
lymphocytes. Since reactive oxygen species (ROS) and mitogen-activated protein kinase (MAPK) play important roles in the proliferation of VSMCs, the present study examined the effects of MPA on intracellular ROS generation, activation of ERK and
p38
MAPK, and the proliferation of VSMCs cultured under platelet derived growth factor (PDGF).
Methods : Human VSMCs obtained from ATCC were cultured with RPMI-1640 containing 10% fetal bovine serum. Near confluent VSMCs were incubated with serum-free media for 48 hours to arrest and synchronize the cell growth. MPA was administered
1
hour
before the addition of PDGF. 5-(and-6)-chloromethyl-2’,7’-dichlorodihydrofluorescein (DCF)-sensitive intracellular ROS was detected by FACS. Activations of ERK1/ERK2 and p38 MAPK were measured by Western blot analysis. Proliferation of VSMC was
assessed
by [3H]-thymidine incorporation. Results
PDGF administered at 10 ng/ml, which induced human VSMCs proliferation, rapidly increased intracellular ROS by 1.6-fold (P<0.05), ERK1/ERK2 activation by 2.1-fold, (P<0.05) and p38 MAPK activation by 1.9-fold (P<0.05), respectively, as compared
to
the
control. MPA 1 and 10μM effectively inhibited PDGF-induced human VSMCs proliferation. MPA also effectively inhibited PDGF-induced intracellular ROS generation as well as ERK1/ERK2 and p38 MAPK activation.
Conclusion : The present study suggests that MPA inhibits PDGF-induced human VSMCs proliferation, possibly by inhibiting intracellular ROS generation and the phosphorylation of ERK1/ERK2 and p38 MAPK.
|