NADPH oxidase pathway is involved in aortic contraction induced by A3 adenosine receptor in mice.
ABSTRACT The NADPH oxidase (Nox) subunits 1, 2 (gp91 phox), and 4 are the major sources for reactive oxygen species (ROS) in vascular tissues. In conditions such as ischemia-reperfusion and hypoxia, both ROS and adenosine are released, suggesting a possible interaction. Our aim in this study was to examine the A(3) adenosine receptor (A(3)AR)-induced vascular effects and its relation to ROS and Nox1, 2, and 4 using aortic tissues from wild-type (WT) and A(3)AR knockout (A(3)KO) mice. The selective A(3)AR agonist 2-chloro-N(6)-(3-iodobenzyl)-adenosine-5'-N-methyluronamide (Cl-IBMECA) (10(-10)-10(-5) M) induced contraction of the aorta from WT but not from A(3)KO mice, and this contraction was inhibited by the Nox inhibitor apocynin (10(-5) M) and the ROS scavengers superoxide dismutase-polyethylene glycol and catalase-polyethylene glycol (100 U/ml each). Cl-IBMECA-induced contraction was not affected by the mast cell degranulator compound 48/80 (100 μg/ml) or the stabilizer cromolyn sodium (10(-4) M). In addition, Cl-IBMECA (10(-7) M) increased intracellular ROS generation by 35 ± 14% in WT but not in A(3)KO aorta, and this increase was inhibited by apocynin (10(-5) M), diphenyleneiodonium chloride (10(-5) M), and the A(3)AR antagonist 3-propyl-6-ethyl-5-[(ethylthio)carbonyl]-2 phenyl-4-propyl-3-pyridine carboxylate (MRS1523) (10(-5) M). Furthermore, Cl-IBMECA selectively increased the protein expression of the Nox2 subunit by 150 ± 15% in WT but not in A(3)KO mice without affecting either Nox1 or 4, and this increase was inhibited by apocynin. The mRNA of Nox2 was unchanged by Cl-IBMECA in either WT or A(3)KO aortas. In conclusion, A(3)AR enhances ROS generation, possibly through activation of Nox2, with subsequent contraction of the mouse aorta.
Article: Protection from myocardial stunning by ischaemia and hypoxia with the adenosine A3 receptor agonist, IB-MECA.[show abstract] [hide abstract]
ABSTRACT: Guinea pig isolated working hearts were exposed to 30-min ischaemia by reducing coronary flow to 10%, followed by reperfusion. Aortic output fell to 4.5+/-4.5% of the pre-ischaemic value at reperfusion, recovering to 48.2+/-14.6% at 20-min post-reperfusion; the index of myocardial stunning. IB-MECA (N(6)-(3-iodobenzyl)adenosine-5'-N-methyluronamide, 3 x 10(-7) M), infused from 10 min into ischaemia, did not affect recovery of aortic output 20 min after reperfusion (41.9+/-1.9%). IB-MECA infused at reperfusion, however, significantly protected against stunning, aortic output recovering to 79.6+/-3.9% at 20-min post-reperfusion. Hypoxic gassing (5% CO(2) in nitrogen, 30 min) of guinea pig isolated paced left atria and papillary muscles reduced the developed tension, recovering to 75% 5 min after re-oxygenation. This myocardial stunning was unaffected by IB-MECA (3 x 10(-7) M) added 10 min into hypoxia. IB-MECA added at reoxygenation significantly improved recovery, which was prevented by the adenosine A(3) receptor antagonist, 1-propyl-3-(3-iodo-4-aminobenzyl)-8-(4-oxyacetate)phenylxanthine (I-ABOPX, 1 x 10(-5) M). Thus, stimulation of adenosine A(3) receptors at reperfusion/reoxygenation in guinea pig cardiac preparations protects against myocardial stunning.European Journal of Pharmacology 10/2003; 477(3):235-45. · 2.52 Impact Factor
Article: Adenosine A(3) receptor suppresses prostate cancer metastasis by inhibiting NADPH oxidase activity.[show abstract] [hide abstract]
ABSTRACT: Prostate cancer is the most commonly diagnosed and second most lethal malignancy in men, due mainly to a lack of effective treatment for the metastatic disease. A number of recent studies have shown that activation of the purine nucleoside receptor, adenosine A(3) receptor (A(3)AR), attenuates proliferation of melanoma, colon, and prostate cancer cells. In the present study, we determined whether activation of the A(3)AR reduces the ability of prostate cancer cells to migrate in vitro and metastasize in vivo. Using severe combined immunodeficient mice, we show that proliferation and metastasis of AT6.1 rat prostate cancer cells were decreased by the administration of A(3)AR agonist N(6)-(3-iodobenzyl) adenosine-5'-N-methyluronamide. In vitro studies show that activation of A(3)AR decreased high basal nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity present in these cells, along with the expression of Rac1 and p47(phox) subunits of this enzyme. Inhibition of NADPH oxidase activity by the dominant-negative RacN17 or short interfering (si)RNA against p47(phox) reduced both the generation of reactive oxygen species and the invasion of these cells on Matrigel. In addition, we show that membrane association of p47(phox) and activation of NADPH oxidase is dependent on the activity of the extracellular signal-regulated kinase (ERK)1/2 mitogen-activated protein kinase pathway. We also provide evidence that A(3)AR inhibits ERK1/2 activity in prostate cancer cells through inhibition of adenylyl cyclase and protein kinase A. We conclude that activation of the A(3)AR in prostate cancer cells reduces protein kinase A-mediated stimulation of ERK1/2, leading to reduced NADPH oxidase activity and cancer cell invasiveness.Neoplasia (New York, N.Y.) 11/2009; 11(11):1132-45. · 5.48 Impact Factor