title: Inhibition of cytokine production and cytotoxic activity of human antimelanoma specific CD8+ and CD4+ T lymphocytes by adenosine-protein kinase A type I signaling.
abstract: The goal of this study was to investigate the effects of adenosine and its stable analogue 2-chloroadenosine (CADO) on the cytotoxic activity and cytokine production by human antimelanoma specific CD8+ and CD4+ T-helper type 1 (Th1) clones. The cytotoxic activity of CD8+ T cells was inhibited by adenosine and CADO. Using Lab MAP multiplex technology, we found that adenosine inhibits production of various cytokines and chemokines by CD8+ and CD4+ T cells. Studies with CGS21680, a specific agonist of adenosine A2A receptor (AdoRA2A), and ZM241385, an AdoRA2-selective antagonist, indicate that the inhibitory effects of adenosine are mediated via cyclic AMP (cAMP)-elevating AdoRA2A, leading to protein kinase A (PKA) activation. Using cAMP analogues with different affinities for the A and B sites of the regulatory subunits of PKAI and PKAII, we found that activation of PKAI, but not of PKAII, mimicked the inhibitory effects of adenosine on T-cell cytotoxic activity and cytokine production. Inhibitors of the PKA catalytic subunits (H89 and PKA inhibitor peptide 14-22) failed to abrogate the inhibitory effects of CADO. In contrast, Rp-8-Br-cAMPS that antagonizes binding of cAMP to the regulatory I subunit and PKA activation was efficient in blocking the inhibitory effect of adenosine on the functional activity of T cells. Our findings on the ability of adenosine to inhibit the effector function of antimelanoma specific T cells suggest that intratumor-produced adenosine could impair the function of tumor-infiltrating T lymphocytes. Thus, blocking the inhibitory activity of tumor-produced adenosine might represent a new strategy for improvement of cancer immunotherapy.
authors.affiliation: Department of Pathology, School of Medicine, University of Pittsburgh, Pittsburgh, Pennsylvania, USA.
authors.forename: Tatiana
authors.initials: T
authors.lastname: Raskovalova
authors.forename: Anna
authors.initials: A
authors.lastname: Lokshin
authors.forename: Xiaojun
authors.initials: X
authors.lastname: Huang
authors.forename: Yunyun
authors.initials: Y
authors.lastname: Su
authors.forename: Maja
authors.initials: M
authors.lastname: Mandic
authors.forename: Hassane M
authors.initials: HM
authors.lastname: Zarour
authors.forename: Edwin K
authors.initials: EK
authors.lastname: Jackson
authors.forename: Elieser
authors.initials: E
authors.lastname: Gorelik
mesh_terms: D015762:2-Chloroadenosine / Q000378:metabolism; D000241:Adenosine / Q000031:analogs & derivatives / Q000378:metabolism*; D015496:CD4-Positive T-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D018414:CD8-Positive T-Lymphocytes / Q000276:immunology* / Q000378:metabolism; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D016207:Cytokines / Q000096:biosynthesis*; D003602:Cytotoxicity, Immunologic; D006801:Humans; D008545:Melanoma / Q000276:immunology*; D043705:Receptor, Adenosine A2A / Q000378:metabolism; D015398:Signal Transduction / Q000276:immunology
chemical_list: D016207:Cytokines; D043705:Receptor, Adenosine A2A; D015762:2-Chloroadenosine; D017868:Cyclic AMP-Dependent Protein Kinases; D000241:Adenosine