Mechanism of anti-proliferation caused by YC-1, an indazole derivative, in cultured rat A10 vascular smooth-muscle cells.
An indazole derivative, YC-1, was identified in this study to be capable of reversibly and effectively inhibiting proliferation of rat A10 vascular smooth-muscle cells (VSMCs) in vitro. YC-1 (1-100 microM) dose-dependently inhibited [3H]thymidine incorporation into DNA in rat A10 VSMCs that were synchronized by serum depletion and then restimulated by addition of 10% foetal calf serum (FCS), whereas FCS-induced [3H]thymidine incorporation into rat synchronized endothelial cells was unaffected by this agent. The dose of YC-1 required to cause inhibition of FCS-induced proliferation was similar to that necessary for the formation of cellular cyclic GMP (cGMP). Guanylate cyclase activity in soluble fractions of VSMCs was activated by YC-1 (1-100 microM), whereas cGMP-specific phosphodiesterase activity was unaffected by this compound. The anti-proliferative effect of YC-1 was mimicked by 8-bromo-cGMP, a membrane-permeable cGMP analogue, and was antagonized by KT 5823 (0.2 microM), a selective inhibitor of protein kinase G. The anti-proliferative effect of YC-1 was also antagonized by Methylene Blue (50 microM), a guanylate cyclase inhibitor, and was potentiated by 3-isobutyl-1-methylxanthine (500 microM), a phosphodiesterase inhibitor. These results verified that YC-1 is a direct soluble guanylate cyclase activator in A10 VSMCs, and the anti-proliferative effect of YC-1 is mediated by cGMP. YC-1 still inhibited FCS-induced DNA synthesis even when added 10-18 h after restimulation of the serum-deprived A10 VSMCs with 10% FCS. Flow cytometry in synchronized populations revealed an acute blockage of FCS-inducible cell-cycle progression at a point in the G1/S-phase in YC-1 (100 microM)-treated cells. The inhibition of proliferation by YC-1 was demonstrated to be independent of cell damage, as documented by several criteria of cell viability. In conclusion, YC-1 reversibly and effectively inhibited the proliferation of VSMCs, suggesting that it has potential as a therapeutic agent in the prevention of vascular diseases.
Yu
S M
SM
Department of Pharmacology, Chang Gung Medical College, Kwei-San, Tao-Yuan, Taiwan.
Cheng
Z J
ZJ
Guh
J H
JH
Lee
F Y
FY
Kuo
S C
SC
D000818:Animals; D002453:Cell Cycle / Q000187:drug effects; D002455:Cell Division / Q000187:drug effects; D002478:Cells, Cultured; D006152:Cyclic GMP / Q000032:analysis; D005434:Flow Cytometry; D007191:Indazoles / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology*; D009131:Muscle, Smooth, Vascular / Q000378:metabolism*; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology*; D051381:Rats
D007191:Indazoles; D010975:Platelet Aggregation Inhibitors; C090937:3-(5'-hydroxymethyl-2'-furyl)-1-benzylindazole; D006152:Cyclic GMP