Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:4.6.1.1 (adenylate cyclase)
 19,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The effects of prostaglandins on adenylate cyclase activity have been examined in membranes purified from normal rat liver and from a series of Morris hepatomas. Prostaglandin E1 gave the greatest stimulation (up to two-fold) in all membranes. However, prostaglandins A1, A2, and F2alpha, although stimulatory in liver and four tumor membranes, were inhibitory of adenylate cyclase activity in membranes from two of the fast-growing tumors. Arrhenius plots yielded broken line curves (at 20 degrees C) for the basal activity of all enzymes. Addition of various prostaglandins caused shifts in the broken line curves and/or produced nonbroken (straight) line curves for the liver and many of the hepatoma adenylate cyclases.
Cancer Biochem Biophys 1976 Aug
PMID:Effect of prostaglandins on adenylate cyclase activities in membranes from liver and transplantable hepatomas. 18 16

In the adrenocortical carcinoma cell, in contrast to normal isolated adrenal cells, 10 to 50 muunits of ACTH do not raise the level of adenosine cyclic 3':5'-monophosphate (cyclic AMP), protein kinase activity, and steroidogenesis. This indicates a lesion in the tumor adenylate cyclase system. Two-tenths to 10 mM cyclic AMP and guanosine cyclic 3':5'-monophosphate (cyclic GMP) which stimulate steroidogenesis in a normal cell, activate protein kinase activity in a concentration-response manner without any detectable rise in steroidogenesis in the adrenocortical carcinoma cell. Cycloheximide and actinomycin D do not inhibit the stimulation of the phosphorylation. These results suggest that the tumor cyclic nucleotide-dependent protein kinase activity is unrelated to steroidogenesis and is also not under the transcriptional or translational control steps. Curiously, muM concentrations of cyclic AMP, in contrast to cyclic GMP, stimulate protein kinase activity. In a normal cell, both cyclic AMP and cyclic GMP, in this concentration range, stimulate protein kinase without an increase in steroidogenesis. It is therefore proposed that, in contrast to the normal cell, there is an additional defect in cyclic GMP-dependent protein kinase.
Cancer Res 1977 Feb
PMID:Metabolic regulation and relationship of endogenous protein kinase activity and steroidogenesis in isolated adrenocortical carcinoma cells of the rat. 18 48

A single tumorigenic dose of methylazoxymethanol acetate increased adenylate cyclase activity in total liver homogenates 70-100% by the seventh day after treatment. The increased activity occurred in the plasma membranes rather than in the nuclei and was accompanied by a significant increase in 5'-nucleotidase activity. The data indicate that the carcinogen may alter the structure of the plasma membrane.
Cancer Lett 1975 Nov
PMID:Effect of methylazoxymethanol acetate on adenylate cyclase and 5'-nucleotidase in rat liver plasma membranes. 18

Some of the regulatory mechanisms of cyclic adenosine monophosphate (AMP) production in human brain tumors were investigated by assessing both cyclic AMP levels and adenyl cyclase activity. A large disparity was found between the levels of cyclic AMP of normal brain and brain-tumor tissue. Cyclic AMP levels were much lower in brain tumors (25.8 pmoles (picomoles)/mg protein) than in normal brain (98.8 pmoles/mg protein). These studies also show that the abnormally low levels of cyclic AMP in tumors parallel those of adenyl cyclase. The mean adenyl cyclase activity of brain tissue was found to be 111.0 pmoles of cyclic AMP/min/mg protein, while that of the tumor was only 23.0 pmoles/min/mg protein. Levels of cyclic AMP and adenyl cyclase activity were inversely related to the degree of malignancy. Attempts to stimulate adenyl cyclase in homogenates of human brain and brain tumors resulted in a similar response in both tissues. Norepinephrone was the most effective stimulant and produced a two- to threefold increase in cyclic AMP production, while histamine had no effect. It is concluded that one of the factors governing tumor growth may be a defect in the adenyl cyclase system.
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PMID:Cyclic AMP and adenyl cyclase in brain tumors. 19 76

A calcitonin-responsive adenylate cyclase has been found in a cell line of a poorly differentiated bronchial carcinoma (BEN cells). The cells have previously been shown to secrete an immunoreactive form of calcitonin in culture. Salmon calcitonin (SCT), porcine calcitonin (PCT) and human calcitonin (CT-M) all stimulated adenylate cyclase activity in particulate preparations. CT-M sulphoxide had little effect. The concentrations of the calcitonins required for half the maximum activation of adenylate cyclase were 6-8, 18 and 90 nm respectively. SCT (30pm) and CT-M (60 pm) increased the intracellular concentration of cyclic AMP from 11-2+/-0-2 (s.e.) to 18-2+/-0-2 and 16-7+/-0-2 respectively over a 2-5-min period. SCT (labelled with 125I) bound to particulate preparations of Ben cells, and competition for binding occurred with unlabelled SCT and CT-M. The concentration of SCT required for half the maximum inhibition of [125I]SCT binding was 11 nm. CT-M sulphoxide inhibited only at high concentration (3 micron). The characteristics of the adenylate cyclase response to SCT did not change over the period between cell adhesion (after subculture) and confluence. However, pre-incubation of cells for 4 h with SCT (150 nm) abolished the subsequent adenylate cyclase response of particulate preparations to further hormone. The practical difficulties encountered in purifying and quantifying the large-mol.-wt. form of CT-M secreted by BEN cells has precluded direct investigation of the potential relationship between hormone secretion and the occurrence of the calcitonin receptor. This relationship is discussed in terms of its possible biological significance.
Br J Cancer 1977 Jun
PMID:Calcitonin-responsive adenylate cyclase in a calcitonin-producing human cancer cell line. 19 16

Gonadotropic hormones are required for the induction and maintenance of tumors arising in ovaries that have been transplanted to the spleens of gonadectomized mice. The characteristics of gonadotropin receptors for human chorionic gonadotropin (HCG)-luteinizing hormone on cells from these tumors of varying size, age, and morphology have been determined. The specific binding of 125I-labeled HCG to cells obtained by collagenase digestion, 15 to 65 weeks postimplantation from granulosa cell or luteinized cell, or mixed granulosa-luteal tumors was analyzed by Scatchard plot. Neither the size, weight, duration of implantation, nor histological morphology affected the receptor-binding affinity [equilibrium dissociation constant (Kd), 6 X 10(-10) M], and, presumably, the receptor is qualitatively similar. In contrast, the number of HCG receptors per cell increased 17-fold and was related to the degree of morphological luteinization of the tumor. HCG-sensitive adenyl cyclase was also demonstrated and compared to HCG binding in a highly luteinized tumor.
Cancer Res 1977 Aug
PMID:Gonadotropin receptors in experimentally induced ovarian tumors in mice. 19 83

Fluoride-stimulated adenylate cyclase is demonstrated inisolated tumor cells of transplantable rat pituitary tumor MtT-F4 in vitro. The intracellular cyclic adenosine 3':5'-monophosphate is lowered in the cells incubated in the presence of synthetic somatostatin. Contrary to the findings reported for normal pituitary, however, the immunoreactive growth hormone release does not change when either somatostatin or phosphodiesterase inhibitors are present in the incubation medium. The presence of dibutyryl cyclic adenosine 3':5'-monophosphate (5 mM) in the incubation medium does not change the rate of growth hormone release by isolated tumor cells.
Cancer Res 1977 Aug
PMID:Effect of somatostatin on growth hormone release by MtT-F4 rat pituitary tumor in vitro. 19 84

The adenylate cyclase activity was measured in chick embryo fibroblasts (CEF) infected with temperature-sensitive mutants (ts) of avian sarcoma virus (ASV). When CEF transformed with a (ts) mutant at 36 degrees C were incubated at the non-permissive temperature (41 degrees C), recovery from the low adenylate cyclase activity detectable in the transformed state was slower than the disappearance of signs of morphological transformation. After a downward shift of the temperature the activity decreased and this change was also slower than the alteration of cell morphology. The affinity of the enzyme system for ATP also changed after, and not during, morphological alteration. No significant difference was observed between the cAMP levels in ASV-transformed and non-infected CEF. These findings are consistent with the idea that adenylate cyclase is not involved in cell transformation and that the change in its activity is secondary to cell transformation.
Int J Cancer 1977 Oct 15
PMID:Adenylate cyclase activity and the cAMP level are not directly correlated with transformation by avian sarcoma viruses. 19 47

A well-differentiated ductal adenocarcinoma of the Syrian golden hamster induced by N-nitrosobis(2-oxopropyl)amine was transplantable to both nude mice and inbred Syrian hamsters. The tumor grew rapidly in the nude mouse (12-fold increase in size at 45 days) in contrast to its growth in hamster (3-fold increase in size at 45 days). A curious finding associated with the slow-growing tumor in the hamster was an intense infiltration of the neoplasm by polymorphonuclear leukocytes unattended by either necrosis or infection. The neoplasm produced mucin and rapidly and specifically bound 125I-labeled secretin, although the degree of nonspecific binding (40.5%) was higher than that of control hamster pancreas (23%). Unstimulated adenyl cyclase activity (pmol cyclic adenosine 3':5'-monophosphate per mg protein) of the neoplasm was significantly higher [3.76 +/- 0.55 (S.E.)] than that of unstimulated normal hamster pancreas (1.03 +/- 0.44). Secretin did not significantly change the level of cyclic adenosine 3':5'-monophosphate (3.3 +/- 0.56) from the unstimulated level in the neoplasm, in contrast to its effect on normal pancreas where the level was increased 3-fold (3.1 +/- 0.75).
Cancer Res 1979 Feb
PMID:Transplantable ductal adenocarcinoma of the Syrian hamster pancreas. 21 89

The glucagon-sensitive adenylate cyclase system, viewed from the perspective of its behavior with isolated membrane preparations, displays far more complex regulatory characteristics than could have been envisioned from its behavior in the intact cell. What has emerged from our studies with isolated hepatic membranes is that glucagon can exert at least three actions which we believe are interdependent: desentization of the receptor, activation of adenylate cyclase, and promotion of adenosine inhibition of adenylate cyclase activity. Although the molecular basis remains unknown, GTP is intimately involved in the three processes. Undoubtedly, further levels of complexity will develop when the enzyme system is dissected and its components become amenable to study at the molecular level. At the moment, it is clear that adenylate cyclase systems are provided with a plethora of regulatory processes for controlling cyclic AMP production both in the absence and presence of hormones.
Natl Cancer Inst Monogr 1978 May
PMID:The actions of hormones on adenylate cyclase systems. 21 57


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