Rat (3Y1) and hamster embryo brain cells were transformed by wild-type adenovirus type 12 or the DNA-minus temperature-sensitive mutant ts401. The ts401-transformed 3Y1 cells, but not the wild-type transformants, displayed a temperature-sensitive response with respect to the following characteristics of the transformed phenotype: morphology, saturation density, growth rate, cloning in soft agar, colony formation on plastic at low cell densities in 1% serum medium, and the T antigen(s). Temperature shift-down experiments showed that the density-dependent inhibition of growth of the ts401-transformed cells was reversible, as was, to some extent, the low efficiency of colony formation at low cell densities in 1% serum. Examination of hamster transformants for their ability to clone in soft agar at permissive and nonpermissive temperatures showed that this property was temperature dependent, again only in the ts401 transformants and not in the wild-type transformants. Alteration in uptake of 2-deoxyglucose or in intracellular cyclic AMP content was not a characteristic of the adenovirustransformed phenotype in the 3Y1 cells. The findings suggest that an active 401 function is required for maintenance of the adenovirus-transformed cell phenotype.
The responsiveness of a growth-regulated rat 3Y1 cell line and five clones of 3Y1 cells transformed by the highly oncogenic human adenovirus type 12 to the catecholamine hormone (-)-isoproterenol was studied. The untransformed cells contained beta-adrenergic receptors characterized by specific binding of the beta-adrenergic receptor antagonist (-)-[3H]dihydroalprenolol, a 9- to 12-fold increase in cyclic AMP production in intact cells after incubation with 10 microM (-)-isoproterenol, and significantly increased adenylate cyclase (ATP pyrophosphatelyase [cyclizing], EC 4.6.1.1) activity in the presence of the hormone. In contrast, (-)-isoproterenol (10 to 100 microM) had no apparent effect on cyclic AMP production or the basal adenylate cyclase activity in the transformed cell lines. Binding studies revealed that untransformed cells contained approximately 19,400 beta-adrenergic receptor sites per cell. Three transformed cell clones tested showed a three- to fourfold loss of beta-adrenergic receptors.
The responsiveness of a growth-regulated rat 3Y1 cell line and five clones of 3Y1 cells transformed by the highly oncogenic human adenovirus type 12 to the catecholamine hormone (-)-isoproterenol was studied. The untransformed cells contained beta-adrenergic receptors characterized by specific binding of the beta-adrenergic receptor antagonist (-)-[3H]dihydroalprenolol, a 9- to 12-fold increase in cyclic AMP production in intact cells after incubation with 10 microM (-)-isoproterenol, and significantly increased adenylate cyclase (ATP pyrophosphatelyase [cyclizing], EC 4.6.1.1) activity in the presence of the hormone. In contrast, (-)-isoproterenol (10 to 100 microM) had no apparent effect on cyclic AMP production or the basal adenylate cyclase activity in the transformed cell lines. Binding studies revealed that untransformed cells contained approximately 19,400 beta-adrenergic receptor sites per cell. Three transformed cell clones tested showed a three- to fourfold loss of beta-adrenergic receptors.
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