OXIDATIVE STRESS INCREASES A(1) ADENOSINE RECEPTOR EXPRESSION BY ACTIVATING NUCLEAR FACTOR KAPPA-B

The A(1) adenosine receptor (A(1)AR) contributes to the cytoprotective action of adenosine under conditions known to generate reactive oxyge n species (ROS). Pharmacological manipulation of A(1)AR expression has been shown to modulate this cytoprotective role. In this study, we pr ovide evidence that ROS generated could increase the expression of the A(1)AR and thereby offset the detrimental effects of ROS. Incubation of DDT1MF-2 smooth muscle cells with ROS-generating chemotherapeutic a gents, such as cisplatin (2.5 mu M) or H2O2 (10 mu M), elicited an inc rease in A(1)AR expression within 24 hr. The induction by H2O2 was red uced by the ROS scavenger catalase but not superoxide dismutase. Inhib ition of nuclear factor kappa B (NF kappa B) by pyrrolidine dithiocarb amate (200 mu M), dexamethasone (100 nM), or genistein (1 mu M) abroga ted the cisplatin-mediated increase in A(1)AR. Cisplatin promoted rapi d translocation of NF kappa B (but not AP-1) to the nucleus, as detect ed by electrophoretic mobility shift assays and by Western blotting. A putative NF kappa B sequence in the A,AR promoter effectively compete d with labeled KB probe for binding in nuclear preparations derived fr om DDT1MF-2 cells. Transient transfection of DDT1MF-2 cells with the A ,AR promoter coupled to firefly luciferase reporter gene led to cispla tin-inducible and pyrrolidine dithiocarbamate-sensitive luciferase act ivity, suggesting the presence of functional NF kappa B binding site(s ) in the A(1)AR promoter sequence. Treatment of cells with (R)-phenyli sopropyladenosine (1 mu M), an agonist of the A(1)AR, reduced cisplati n-mediated lipid peroxidation, which was reversed after blockade of th e A(1)AR. These data suggest that ROS can increase the expression of t he A(1)AR by activating NF kappa B regulatory site(s) on this gene and thereby enhance the cytoprotective role of adenosine.