M. Delrio et al., ANTIPROLIFERATIVE EFFECTS OF PCA-4230, A NEW ANTITHROMBOTIC DRUG, IN VASCULAR SMOOTH-MUSCLE CELLS, British Journal of Pharmacology, 120(7), 1997, pp. 1360-1366
1 In the present study we examined the effects of PCA-4230, A novel an
tithrombotic agent, on the growth of cultured A10 vascular smooth musc
le cells (rat aorta). 2 The action of PCA-4230 on cell proliferation a
nd on serum-induced DNA synthesis was determined by measuring the cell
number and the incorporation of the thymidine analogue 5-bromo-2'-deo
xyuridine (BrdU), respectively. 3 PCA-4230 reversibly inhibited vascul
ar smooth muscle cell proliferation. The increase in cell number was s
ignificantly reduced in the presence of 1 and 50 mu M PCA-4230. 4 DNA
synthesis was concentration-dependently inhibited by PCA-4230 (0.5 to
50 mu M) in A10 cells that were synchronized by 48 h serum starvation
and then re-stimulated by serum repletion, with an IC50 value of 13 mu
M. However, serum-induced DNA synthesis in bovine aortic endothelial
cells was not significantly affected by PCA-4230. In addition, PCA-423
0 (50 mu M) caused a significant drop in PDGF-BB-mediated BrdU incorpo
ration in A10 cells. 5 The effect of PCA-4230 on serum-induced DNA syn
thesis was compared to that elicited by nifedipine, another dihydropyr
idine-class inhibitor of vascular smooth muscle proliferation. PCA-423
0 (10 mu M) elicited a degree of inhibition similar to that of nifedip
ine at equimolar concentration. 6 To define the nature of the cell pro
liferation inhibition, an evaluation of cell cycle progression was und
ertaken. Flow cytometry studies of DNA content in synchronized cells r
evealed a block of the serum-inducible cell cycle progression. This in
hibitory effect was markedly reduced when PCA-4230 was added 2 h after
serum repletion. 6 Accordingly, PCA-4230 (50 mu M) caused a 95 and 90
% decrease in the elevation of c-fos and c-jun proto-oncogenes express
ion as evaluated by Northern blot analysis of mRNA induced early after
serum addition. 7 The present results indicate that PCA-4230 inhibits
vascular smooth muscle cell proliferation, in culture, by altering th
e cell cycle progression. Flow cytometric studies of DNA content and t
he down regulation of c-fos and c-jun proto-oncogenes, suggest that th
e drug is acting at the early G(0)/G(1) transition phase. PCA-4230 may
hold promising potential for the prevention of structural abnormaliti
es of blood vessels associated with atherosclerosis and vascular disea
ses.