Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: UMLS:C0027651 (tumor)
 685,946 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

During growth of Ehrlich ascites tumor cells in vivo, the proportion of cells in the S phase of the proliferative cell cycle decreases in a manner analogous to the decreasing growth fraction often associated with the growth of solid tumors. An examination of biochemical parameters that might regulate the growth fraction of Ehrlich ascites tumors by causing accumulation of cells in G1-G0 shows that (a) the tumor progresses from an aerobic to an anerobic state as it approaches the plateau phase of growth, as indicated by lactate dehydrogenase content, but cellular adenosine triphosphate content remains constant; (b) tumor-specific growth inhibitors (chalones) are not detectable in cell-free ascites fluid from plateau-phase tumors; (c) electrophoretically identifiable soluble proteins isolated from tumor cells that have been exposed to labeled amino acids in vivo are qualitatively identical during early and late tumor growth; and (d) ornithine decarboxylase activity increases in a bimodal fashion in the first 10 hr after transplantation of 10(7) cells and then declines rapidly during the first few days of growth. The second (and larger) of the two ornithine decarboxylase increases coincides with the surge of cells from G1-G0 into S phase, suggesting that this enzyme, or the polyamines that it synthesizes, may play a role in controlling the growth fraction of this cell population.
 ...
PMID:The role of adenosine triphosphate, chalones, and specific proteins in controlling tumor growth fraction. 12 98

The levels of superoxide anion production, cytochrome P450, ornithine decarboxylase(E.C.4.1.1.17), catalase(E.C.1.11.1.6), deoxyribonucleic acid, ribonucleic acid and protein have been studied in human kidney and renal clear-cell adenocarcinoma tissues. The levels of superoxide anion production, ornithine decarboxylase, catalase and ribonucleic acid in the tumor tissue are very different from those in the kidney.
 ...
PMID:Superoxide anions and other components of human renal adenocarcinoma. 17 36

Tumor promoters and anti-promoters have been shown to modify the induction of ornithine decarboxylase, the production of plasminogen activator, and the recovery of induced mutations. Data were presented to show that the recovery of mutagen-induced ouabain-resistant mutations in cultured Chinese hamster cells is increased with a tumor-promoter treatment and reduced by anti-promoter treatments. The results suggest that many induced mutations can either be repressed or derepressed by promoters or anti-promoters. The results also support the hypothesis that tumor initiation is due to a mutagenic event, while tumor promotion is the result of an epigenetic process involving cyclic nucleotide modulation of gene expression.
 ...
PMID:In vitro assay for tumor promoters and anti-promoters. 21 6

The effect of different phorbol esters and of mechanical treatment on the activity of ornithine decarboxylase in mouse epidermis in vivo was investigated. The strong promoter 12-O-tetradecanoylphorbol-13-acetate as well as the weak promoters phorbol dibenzoate and the 12-O-tetradecanoylphorbol-13-acetate analog 12-O-tetradeca-2-cis, 4-trans-6,8-tetraenoylphorobol-13-acetate strongly increased the activity of the enzyme and the intraepidermal level of putrescine, with a maximum at 5 hr after application, when applied in doses which evoke comparable proliferative and irritant responses in skin. The hyperplasiogenic but nonirritant and almost nonpromoting 4-O-methyl ether of 12-O-tetradecanoylphorbol-13-acetate did not show such effects. Mechanical removal of the uppermost horny layer led to a considerable increase of ornithine decarboxylase activity after 4 to 8 hr, while skin massage showed only a minute effect under conditions in which both treatments exhibit about the same mitogenic efficiency. Neither manipulation promotes tumor development. After skin massage, the induction of ornithine decarboxylase was influenced neither by treatments which alter the cyclic adenosine 3',5'-monophosphate level in epidermis (inhibition of phosphodiesterase, beta-adrenergic stimulation, and injection of dibutyryl cyclic adenosine 3',5'-monophosphate) nor by injection of epidermal G1 chalone. The results indicate that no clear-cut correlation exists between epithelial cell proliferation, development of hyperplasia, and tumor promotion on the one hand and an activation of epidermal ornithine decarboxylase on the other.
 ...
PMID:Ornithine decarboxylase activity, cell proliferation, and tumor promotion in mouse epidermis in vivo. 22 17

The tumor promoter 12-O-tetradecanoylphorbol-13-acetate and the antileukemic agent mezerein are diterpene esters of plant origin with certain structural similarities. Both compounds, when applied topically to mouse skin, were equipotent on a molar basis in inducing hyperplasia, inflammation, and ornithine decarboxylase activity, as well as in reducing cyclic adenosine 3':5'-monophosphate accumulation in response to beta-adrenergic stimulation. In contrast, mezerein was much less effective as a tumor promoter; the phorbol ester at 8.5 nmol/application yielded 78-fold more tumors than did 8.5 nmol mezerein per application to similarly initiated SENCAR mice. The superiority of the phorbol ester was nearly as great in CD-1 mice.
 ...
PMID:Effects of 12-O-tetradecanoylphorbol-13-acetate and mezerein on epidermal ornithine decarboxylase activity, isoproterenol-stimulated levels of cyclic adenosine 3':5'-monophosphate, and induction of mouse skin tumors in vivo. 22 91

Transition of proliferating Ehrlich ascites tumor cells (3 days after transplantation) to the non-proliferating status (8--14 days after transplantation) was associated with an increase in total mono (ADP-ribose) protein conjugates. This increase was largely confined to the NH2OH-resistant subfraction. When the amounts of mono-(ADP-ribose) conjugates from 20% trichloroacetic acid precipitates were compared with those from 5% perchloric acid precipitates, no significant differences were seen. This fact excludes histone H1 as a major mono (ADP-ribose) acceptor in vivo in these cells. Transition to the resting state was also associated with a small decrease in NAD levels, and with no significant changes of total ADP-ribose transferase activity. However intrinsic ADP-ribose transferase activity as expressed in permeabilized cells was increased, being correlated with the changes in the level of the NH2OH-resistant mono (ADP-ribose) protein conjugates. This shows that alterations in intrinsic transferase activity may, in general, indicate similar alterations in major subfractions of ADP-ribose conjugates. Intrinsic ADP-ribose transferase activity exhibited an inverse relationship to ornithine decarboxylase activity.
 ...
PMID:Intrinsic ADP-ribose transferase activity versus levels of mono(adp-ribose)protein conjugates in proliferating Ehrlich ascites tumor cells. 23 Oct 3

Hypotheses are presented of the detailed molecular structure of two prostaglandin receptors both concerned in tumor-promotion processes. These structures have been derived by the comparison of the molecular structure of agents active at the site with (i) a simple theoretical protein structure and (ii) the known x-ray structure of phospholipase A2. The first model receptor is stimulatory to the tumor-promotion process and may be located on the control system for ornithine decarboxylase. The binding of PG here is cooperative with the binding of Ca++. Naturally-occurring agonists at this receptor may include members of the cathartic class of drugs such as colocynth, chrysarobin, etc. Naturally-occurring antagonists at this site may include a number of anti-tumor compounds such as datiscoside. The second model receptor (PGE1) is inhibitory to the tumor-promotion process and is located at a specific allosteric site on the x-ray-determined structure of phospholipase A2. This site overlaps for one for lysolecithin (excitatory), for which tumor-promoting phorbol esters such as TPA are agonists and some anti-tumor drugs such as maytansine may be antagonists.
 ...
PMID:On the molecular structure of some prostaglandin receptors. 23 33

A method for producing solid tumors in rat liver or spleen by local inoculation of Yoshida sarcoma or Hirosaki sarcoma was developed by careful selection of rat strains. After development of the tumor, the liver was isolated and perfused with a mixture of calf serum and fluorocarbon. Addition of corticoid hormone to the perfusion fluid induced tyrosine aminotransferase in normal tissue of the liver and to a lesser degree in the tumor tissue. Corticoid did not cause any detectable induction of thymidine kinase in normal tissue of the liver, but caused slight but definite induction of the enzyme in the tumor tissue. Ornithine decarboxylase was induced in the normal tissue by perfusion with serum alone, even without corticoid, but no enzyme induction was observed in the tumor tissue. The low level of this enzyme found in solid tumor tissue might be due to the fact that the enzyme was measured in the late period of tumor growth, because, in experiments with ascites tumor cells, higher enzyme activities were observed in the early period of growth.
 ...
PMID:Induction of ornithine decarboxylase, tyrosine aminotransferase, and thymidine kinase by glucocorticoid in isolated, perfused liver after tumor inoculation. 24 80

12-O-Tetradecanoyl phorbol-13-acetate (TPA), a tumor promoter, stimulates DNA synthesis in mouse epidermal cells in vivo and in vitro. This response appears to be mediated through polyamine metabolism because ornithine decarboxylase (L-ornithine carboxy-lyase, EC 4.1.1.17)activity is markedly increased shortly after promoter exposure and this induction varies in magnitude according to dose and promoter potency of a series of phorbol esters. In vitro, exogenous putrescine (0.01-10 mM) results in a dose-related increase and prolongation of promoter-stimulated DNA DNA synthesis, a phenomenon noted in other systems of polyamine-mediated growth stimulation. The anti-inflammatory steroid fluocinolone acetonide (FA), an inhibitor of tumor promotion, prevents TPA stimulation of epidermal proliferation in vivo and in vitro. In vitro, FA most effectively prevents stimulation of DNA synthesis when applied is not required. Paradoxially, FA potentiates the increase in ornithine decarboxylase activity after TPA administeration both in vivo and in vitro. Furthermore, the inhibition of TPA-stimulated DNA synthesis by FA in vitro can be reversed by exogenous putrescine. These results suggestthat FA exerts its antipromotion effect by reducing the sensitivity of the cell to polyamines or by reducing intracellular polyamine levels.
 ...
PMID:Dissociation of tumor promoter-stimulated ornithine decarboxylase activity and DNA synthesis in mouse epidermis in vivo and in vitro by fluocinolone acetonide, a tumor-promotion inhibitor. 26 43

Morphologic alterations in epithelium, caused by imcompetency of retinoids in a diet, were similar to those, obtained after treatment with chemical carcinogens. This suggests to use various derivatives of nature retinoids for treatment of epithelial tumors in skin and other tissues. Cultures of mouse prostatic gland and skin epithelium from metatarsus of chicken embryo were used for study of antitumoral activity of various synthetic retinoids. The most active preparations proved to be cyclopentenyl- and trimethyl methoxyphenyl ethyl ester derivatives of retinolic acid. The antitumoral effect of retinolic acid and its derivatives appears to involve a tight binding of the preparations with specific protein and inhibition of ornithine decarboxylase in tumor. The enzyme is well known to be related to synthesis of DNA, RNA and protein.
 ...
PMID:[Antineoplastic action of retinol and its derivatives (retinoids)]. 37 86


1 2 3 4 5 6 7 8 9 10 Next >>