Dipyridamole inhibits PDGF-stimulated human peritoneal mesothelial cell proliferation.
BACKGROUND
It has been proposed that proliferation of human peritoneal mesothelial cells (HPMCs) accompanied by collagen synthesis may contribute to the development of peritoneal fibrosis (PF) in patients of long-term continuous ambulatory peritoneal dialysis (CAPD). However, the precise molecular mechanism regulating HPMC proliferation has never been reported. Dipyridamole has been reported to have potential as an antiproliferative and antifibrotic agent. We investigated the mechanism and effect of dipyridamole in regulation of HPMC proliferation.


METHODS
HPMCs were cultured from human omentum by an enzyme digestion


METHODS
Cell proliferation was measured by the methyltetrazolium assay and intracellular cAMP was measured using an enzyme immunoassay kit. Cell-cycle distribution of HPMC was analyzed by flow cytometry. Extracellular signal-regulated protein kinase (p44/p42 ERK) activity and expressions of cell-cycle proteins (cyclin D(1), CDK4, pRB and p27(Kip1)) were determined by Western blotting.


RESULTS
The addition of DP suppressed PDGF-stimulated HPMC proliferation by cell-cycle arrest at the G1 phase. The antimitogenic effect of dipyridamole was mediated through the cAMP pathway. PDGF (25 ng/mL) increased the ERK1/2 activity of HPMC within 15 minutes, which maximized at 30 minutes, and the pretreatment with dipyridamole (17 microg/mL) substantially reduced the ERK response to PDGF by approximately 78.5%. PDGF induced elevated protein levels of cyclin D(1), but the CDK4 protein level did not change. Dipyridamole and DBcAMP had no effect on the levels of cyclin D(1) and CDK4 in PDGF-stimulated HPMC. PDGF decreased p27(Kip1) and induced pRB phosphorylation of HPMC. In contrast, dipyridamole prevented PDGF-induced p27(Kip1) degradation and attenuated PDGF-stimulated pRB phosphorylation.


CONCLUSIONS
Dipyridamole appears to inhibit PDGF-stimulated HPMC proliferation through attenuated ERK activity, preservation of p27(Kip1), and decreased pRB phosphorylation. Thus, dipyridamole may have therapeutic efficacy to prevent or alleviate PF.
Hung
K Y
KY
Department of Internal Medicine, Center for Optoelectronic Biomedicine, National Taiwan University, Taipei, Taiwan, ROC.
Chen
C T
CT
Yen
C J
CJ
Lee
P H
PH
Tsai
T J
TJ
Hsieh
B S
BS
D003994:Bucladesine / Q000494:pharmacology; D018797:Cell Cycle Proteins / Q000378:metabolism*; D002455:Cell Division / Q000187:drug effects; D000242:Cyclic AMP / Q000378:metabolism; D050760:Cyclin-Dependent Kinase Inhibitor p27; D016213:Cyclins / Q000378:metabolism; D004176:Dipyridamole / Q000494:pharmacology*; D004789:Enzyme Activation; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D004847:Epithelial Cells / Q000187:drug effects; D016193:G1 Phase; D006801:Humans; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D010537:Peritoneum / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D010982:Platelet-Derived Growth Factor / Q000037:antagonists & inhibitors*; D025521:Tumor Suppressor Proteins
D018797:Cell Cycle Proteins; D016213:Cyclins; D004791:Enzyme Inhibitors; D010982:Platelet-Derived Growth Factor; D025521:Tumor Suppressor Proteins; D050760:Cyclin-Dependent Kinase Inhibitor p27; D003994:Bucladesine; D004176:Dipyridamole; D000242:Cyclic AMP; D020928:Mitogen-Activated Protein Kinases