Potentiation of adenosine A1 receptor-mediated inositol phospholipid hydrolysis by tyrosine kinase inhibitors in CHO cells.
1. The effect of protein tyrosine kinase inhibitors on human adenosine A1 receptor-mediated [3H]-inositol phosphate ([3H]-IP) accumulation has been studied in transfected Chinese hamster ovary cells (CHO-A1) cells. 2. In agreement with our previous studies the selective adenosine A1 receptor agonist N6-cyclopentyladenosine (CPA) stimulated the accumulation of [3H]-IPs in CHO-A1 cells. Pre-treatment with the broad spectrum tyrosine kinase inhibitor genistein (100 microM; 30 min) potentiated the responses elicited by 1 microM (199+/-17% of control CPA response) and 10 microM CPA (234+/-15%). Similarly, tyrphostin A47 (100 microM) potentiated the accumulation of [3H]-IPs elicited by 1 microM CPA (280+/-32%). 3. Genistein (EC50 = 13.7+/-1.2 microM) and tyrphostin A47 (EC50 = 10.4+/-3.9 microM) potentiated the [3H]-IP response to 1 microM CPA in a concentration-dependent manner. 4. Pre-incubation with the inactive analogues of genistein and tyrphostin A47, daidzein (100 microM; 30 min) and tyrphostin A1 (100 microM; 30 min), respectively, had no significant effect on the accumulation of [3H]-IPs elicited by 1 microM CPA. 5. Genistein (100 microM) had no significant effect on the accumulation of [3H]-IPs produced by the endogenous thrombin receptor (1 u ml(-1); 100+/-10% of control response). In contrast, tyrphostin A47 produced a small augmentation of the thrombin [3H]-IP response (148+/-13%). 6. Genistein (100 microM) had no effect on the [3H]-IP response produced by activation of the endogenous Gq-protein coupled CCK(A) receptor with the sulphated C-terminal octapeptide of cholecystokinin (1 microM CCK-8; 96+/-6% of control). In contrast, tyrphostin A47 (100 microM) caused a small but significant increase in the response to 1 microM CCK-8 (113+/-3% of control). 7. The phosphatidylinositol 3-kinase inhibitor LY 294002 (30 microM) and the MAP kinase kinase inhibitor PD 98059 (50 microM) had no significant effect on the [3H]-IP responses produced by 1 microM CPA and 1 microM CCK-8. 8. These observations suggest that a tyrosine kinase-dependent pathway may be involved in the regulation of human adenosine A1 receptor mediated [3H]-IP responses in CHO-A1 cells.
Dickenson
J M
JM
Institute of Cell Signalling and School of Biomedical Sciences, Queen's Medical Centre, Nottingham.
Hill
S J
SJ
D000818:Animals; D016466:CHO Cells; D006224:Cricetinae; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D019833:Genistein / Q000494:pharmacology; D006801:Humans; D006868:Hydrolysis; D007295:Inositol Phosphates / Q000378:metabolism*; D020929:Mitogen-Activated Protein Kinase Kinases; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D011494:Protein Kinases / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D043886:Receptor, Cholecystokinin A; D011949:Receptors, Cholecystokinin / Q000378:metabolism; D018047:Receptors, Purinergic P1 / Q000378:metabolism*; D018179:Receptors, Thrombin / Q000378:metabolism; D014162:Transfection; D014316:Tritium; D020032:Tyrphostins / Q000494:pharmacology
D004791:Enzyme Inhibitors; D007295:Inositol Phosphates; D043886:Receptor, Cholecystokinin A; D011949:Receptors, Cholecystokinin; D018047:Receptors, Purinergic P1; D018179:Receptors, Thrombin; D020032:Tyrphostins; D014316:Tritium; C060152:tyrphostin 47; D019833:Genistein; D011494:Protein Kinases; D019869:Phosphatidylinositol 3-Kinases; D011505:Protein-Tyrosine Kinases; D020929:Mitogen-Activated Protein Kinase Kinases