cGMP-independent anti-tumour actions of the inhibitor of soluble guanylyl cyclase, ODQ, in prostate cancer cell lines.
OBJECTIVE
Soluble guanylyl cyclase (sGC) is a receptor for nitric oxide that generates cGMP. This second messenger molecule has established roles in cellular physiology; however, less is known about its effects in tumour cells.


METHODS
The effects of 1H-[1,2,4]oxadiazolo[4,3-a]quinoxalin-1-one (ODQ) and 4H-8-bromo-1,2,4-oxadiazolo(3,4-d)benz(b)(1,4)oxazin-1-one (NS2028), both selective sGC inhibitors on proliferation, death and migration were determined in prostate cancer cell lines.


RESULTS
Western blot analysis confirmed the presence of alpha1 and beta1 subunits of sGC in LNCaP and PC-3 cells. Sodium nitroprusside (SNP) increased cGMP accumulation in LNCaP and PC-3, but not DU-145 cells. SNP-stimulated cGMP production in LNCaP cells was dose-dependently reduced by ODQ, with more than 90% inhibition being observed at 0.1 microM. ODQ activated caspase-3 in all three cell lines, but not in normal prostate epithelial cells, at concentrations over 10 muM. High concentrations of ODQ also promoted DNA fragmentation and nucleosome accumulation in the cytosol of LNCaP cells. Interestingly, the chemically related inhibitor, NS2028 was without effect on caspase-3. In addition, ODQ inhibited LNCaP, Du145 and PC-3 cell growth. Finally, although fibroblast growth factor-2 did not enhance cGMP levels in LNCaP cells, its ability to stimulate LNCaP motility was abolished by ODQ.


CONCLUSIONS
These observations taken together suggest that the action of ODQ in LNCaP cells did not reflect sGC inhibition. We conclude that ODQ promotes cell death and inhibits growth and migration of prostate cancer cells and that these actions are independent of its effects on GMP levels.
Haramis
G
G
'G.P. Livanos and M. Simou' Laboratories, Department of Critical Care and Pulmonary Services, Evangelismos Hospital, University of Athens School of Medicine, Athens, Greece.
Zhou
Z
Z
Pyriochou
A
A
Koutsilieris
M
M
Roussos
C
C
Papapetropoulos
A
A
D000970:Antineoplastic Agents / Q000494:pharmacology*; D053148:Caspase 3 / Q000378:metabolism; D016923:Cell Death / Q000187:drug effects; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D006152:Cyclic GMP / Q000096:biosynthesis / Q000378:metabolism*; D053938:DNA Fragmentation / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006162:Guanylate Cyclase / Q000037:antagonists & inhibitors*; D006801:Humans; D008297:Male; D009599:Nitroprusside / Q000494:pharmacology; D010069:Oxadiazoles / Q000494:pharmacology*; D010078:Oxazines / Q000494:pharmacology*; D011471:Prostatic Neoplasms / Q000378:metabolism / Q000473:pathology; D034622:RNA Interference; D012995:Solubility
D000970:Antineoplastic Agents; D004791:Enzyme Inhibitors; C111257:NS 2028; D010069:Oxadiazoles; D010078:Oxazines; D009599:Nitroprusside; D053148:Caspase 3; D006162:Guanylate Cyclase; D006152:Cyclic GMP