Isolation of mutant adrenocortical tumor cells resistant to cyclic nucleotides.
A somatic cell genetic approach was used to study the role of cyclic nucleotides in adrenal steroidogenesis. 8-Bromoadenosine 3',5'-monophosphate (8BrcAMP) stimulated steroidogenesis (K'd=0.1 mM) in cultured mouse adrenocortical tumor cells (Clone Y1). In addition, 8BrcAMP inhibited Y1 cell growth and caused Y1 cell monolayers to assume a rounded morphology. As a consequence, 8BrcAMP (at concentrations greater than or equal to 0.4 mM) reduced the relative plating efficiency of Y1 cells to less than 10(-5). Y1 cells were mutagenized with ethyl methanesulfonate (300 microgram/ml) and grown in the presence of 0.4 mM 8BrcAMP. A surviving colony (8BrcAMPr-1) was shown to be resistant to growth inhibition (relative plating efficiency at 1.0 mM 8BrcAMP=50 percent)) and to morphological changes induced by 8BrcAMP. 8BrcAMPr-1 cells had diminished steroidogenic responses to cyclic nucleotides and to ACTH (less than or equal to 33 percent of maximum). In 8BrcAMP(R)-1 cells, adenylate cyclase activity remained responsive to ACTH, and cyclic AMP phosphodiesterase activity was not increased. These data suggest that 8BrcAMPr-1 cells are defective at a point common to cyclic AMP action on growth, morphology and steroidogenesis. The associated decrease in responsiveness of the steroidogenic pathway to ACTH suggests that ACTH-regulated steroidogenesis is via a cyclic nucleotide-mediated mechanism.
D015105:3',5'-Cyclic-AMP Phosphodiesterases / Q000378:metabolism; D000262:Adenylyl Cyclases / Q000378:metabolism; D000306:Adrenal Cortex Neoplasms / Q000378:metabolism*; D000310:Adrenal Gland Neoplasms / Q000378:metabolism*; D000324:Adrenocorticotropic Hormone / Q000494:pharmacology; D000818:Animals; D001966:Bromine; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D000242:Cyclic AMP / Q000494:pharmacology*; D004273:DNA, Neoplasm / Q000378:metabolism; D004351:Drug Resistance; D051379:Mice; D009154:Mutation; D013256:Steroids / Q000096:biosynthesis; D014970:Xanthines / Q000494:pharmacology
D004273:DNA, Neoplasm; D013256:Steroids; D014970:Xanthines; D000324:Adrenocorticotropic Hormone; D000242:Cyclic AMP; D015105:3',5'-Cyclic-AMP Phosphodiesterases; D000262:Adenylyl Cyclases; D001966:Bromine