Vasodilator-stimulated phosphoprotein (VASP) phosphorylation provides a biomarker for the action of exisulind and related agents that activate protein kinase G.
Recent studies provide evidence that exisulind and two potent derivatives, CP461 and CP248, induce apoptosis in colon cancer cells by inhibiting cyclic GMP (cGMP)-specific phosphodiesterases (phosphodiesterases 2 and 5). This causes an increase in intracellular levels of cGMP, thus activating the cGMP-dependent protein kinase G (PKG), which then activates pathways that lead to apoptosis. To further examine this mechanism and to provide a potential in vivo biomarker for activation of this pathway, we examined phosphorylation of the vasodilator-stimulated phosphoprotein (VASP), a ubiquitously expressed endogenous substrate for PKG. We found that VASP was phosphorylated after treating SW480 colon cancer cells with exisulind, CP461, or CP248. CP248-induced VASP phosphorylation was inhibited by a specific PKG inhibitor but not by a protein kinase A inhibitor. The drug 3-(5'-hydroxymethyl-2'-furyl)-benzylindazole and nitric oxide donors that activate cellular guanylyl cyclase and thus increase cellular levels of cGMP also caused VASP phosphorylation. With all of these agents, the phosphorylation of VASP was associated with increased intracellular levels of cGMP and the induction of apoptosis. We also demonstrated direct in vivo phosphorylation of VASP with constitutively activated mutants of PKG. These results suggest that VASP phosphorylation can provide a useful endogenous cellular biomarker for anticancer agents that cause cGMP-mediated apoptosis.
Deguchi
Atsuko
A
Herbert Irving Comprehensive Cancer Center, Columbia University, New York, New York 10032, USA.
Soh
Jae-Won
JW
Li
Han
H
Pamukcu
Rifat
R
Thompson
W Joseph
WJ
Weinstein
I Bernard
IB
D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D017209:Apoptosis; D015415:Biomarkers; D015153:Blotting, Western; D019556:COS Cells; D015815:Cell Adhesion Molecules / Q000378:metabolism*; D017868:Cyclic AMP-Dependent Protein Kinases / Q000037:antagonists & inhibitors; D006152:Cyclic GMP / Q000378:metabolism; D017869:Cyclic GMP-Dependent Protein Kinases / Q000378:metabolism*; D004789:Enzyme Activation; D004791:Enzyme Inhibitors; D006801:Humans; D008840:Microfilament Proteins; D009154:Mutation; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation; D013467:Sulindac / Q000031:analogs & derivatives* / Q000378:metabolism* / Q000494:pharmacology; D013997:Time Factors; D014407:Tumor Cells, Cultured; D000098662:Vasodilator-Stimulated Phosphoprotein
C439285:(5-fluoro-2-methyl-1-(4-pyridyl)methylene-3-(N-benzyl)-indene)-acetamide hydrochloride; D000970:Antineoplastic Agents; D015415:Biomarkers; D015815:Cell Adhesion Molecules; D004791:Enzyme Inhibitors; D008840:Microfilament Proteins; D010726:Phosphodiesterase Inhibitors; D010750:Phosphoproteins; D000098662:Vasodilator-Stimulated Phosphoprotein; D013467:Sulindac; D017868:Cyclic AMP-Dependent Protein Kinases; D017869:Cyclic GMP-Dependent Protein Kinases; D006152:Cyclic GMP; C025463:sulindac sulfone