Aberrant cyclic adenosine 3':5'-monophosphate metabolism in cultures of tumorigenic rat urothelium.
The cyclic adenosine 3':5'-monophosphate (cyclic AMP) metabolism of stratified normal rat urothelium propagated in vitro on a floating collagen matrix was characterized and used as a basis for identifying potential biochemical lesions in tumorigenic cell lines. The four neoplastic urothelial cell types studied (AY-27, AY-32, AY-33, and AY-34) were derived from Fischer 344 rats fed the carcinogen N-[4-(5-nitro-2-furyl)-2-thiazolyl]formamide. Epinephrine or prostaglandin E1 caused a rise in the cyclic AMP content of normal cultures which was potentiated in the presence of the cyclic nucleotide phosphodiesterase inhibitor 1-methyl-3-isobutylxanthine or by forskolin, a diterpene activator of adenylate cyclase in intact cells. The expected, normal profile of cyclic AMP accumulation in response to beta-adrenergic receptor agonists was epinephrine greater than norepinephrine greater than phenylephrine. By every measure, the tumorigenic AY-27 cells demonstrated an overall decrease of functional adenylate cyclase activity. This was evidenced most by the low accumulation of cyclic AMP observed in response to forskolin. While prostaglandin E1 elicited a heightened cyclic AMP level in these cells, their vanishingly low response to catecholamines also suggested a potential lack of functional beta-adrenergic receptors. Cyclic AMP phosphodiesterase activity was elevated in soluble enzyme preparations obtained from cultures of AY-27 cells. Observations of AY-32 cells were diametrically opposite to the findings with AY-27 cells. In AY-32 cells, prostaglandin E1 receptors appeared to be functionally absent. The beta-adrenergic receptor agonist response profile was abnormal in AY-32 cells. Norepinephrine produced a greater accumulation of cyclic AMP than epinephrine, and phenylephrine stimulated a much greater than normal response. Forskolin stimulation indicated an average level of adenylate cyclase activity in AY-32 cultures. Soluble preparations from AY-32 cells demonstrated a normal amount of cyclic AMP phosphodiesterase activity. AY-33 cells were comparable to normal urothelial cells in all respects save one. These tumorigenic cells had elevated levels of cyclic AMP phosphodiesterase activity. AY-34 cells, like AY-32 cells, were deficient in their responsiveness to prostaglandin E1. However, unlike the other tumorigenic lines, AY-34 cells had an excess of adenylate cyclase as demonstrated by their extraordinary responsiveness to forskolin. In addition, the accumulation of cyclic AMP in AY-34 cells in response to stimulation by epinephrine and norepinephrine, but not phenylephrine, was unusually great.(ABSTRACT TRUNCATED AT 400 WORDS)
Chlapowski
F J
FJ
Nemecek
G M
GM
D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000378:metabolism; D000255:Adenosine Triphosphate / Q000378:metabolism; D000818:Animals; D002250:Carbon Radioisotopes; D002460:Cell Line; D002471:Cell Transformation, Neoplastic; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000378:metabolism*; D004848:Epithelium / Q000378:metabolism; D007700:Kinetics; D051381:Rats; D011919:Rats, Inbred Strains; D014316:Tritium; D001743:Urinary Bladder / Q000378:metabolism*; D001749:Urinary Bladder Neoplasms / Q000378:metabolism*
D002250:Carbon Radioisotopes; D014316:Tritium; D000255:Adenosine Triphosphate; D000242:Cyclic AMP; D015105:3',5'-Cyclic-AMP Phosphodiesterases