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

We have examined the proteins secreted into the growth medium by normal and transformed cells. Transformed cell lines from several mammalian species all secrete proteins in the 58,000 dalton molecular weight range. These proteins are all immunologically related and are secreted at low levels or not at all by the parental normal cell lines. Secretion of the 58K proteins occurs with either DNA or RNA virus transformation and with spontaneous transformation. The transformed cells also secrete phosphoproteins in the same size range, but these are immunologically distinct from the 58K proteins mentioned above. The sizes of the phosphoproteins are species-specific and unrelated to the transforming virus. Incubation of conditioned media from transformed cell cultures with gamma-32P-ATP labels phosphoproteins of the same sizes, indicating the presence in the media of both protein kinase and substrate. All three properties (58K protein, phosphoprotein, in vitro phosphorylation) are closely correlated with transformation in cells transformed by temperature-sensitive viruses. The biological implications of these results remain unknown, but the results may be relevant to recent data on the (phospho)proteins and protein kinase encoded by RNA tumor viruses and the molecular basis of the transformed phenotype.
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PMID:Transformed mammalian cells secrete specific proteins and phosphoproteins. 8 65

The "thermostable" B. thuringiensis exotoxin is active on cell cultures of Mammals "in vitro", except on the KB strain from a human tumor. The primary cultures are the most sensitive: first, with monkey kidney cells, the growth is inhibited by 0.1 mg of toxin per ml; next, the young rabbit kidney cells react to 0.25 mg of toxin per ml. The established lines of cells come last: human diploid cells (Lyon 4) and heteroploid cells (BHK21C13), with the same active dose of 1 mg of toxin per ml. No protection is obtained by adding ATP to monkey kidney cells at the same time as the exotoxin.
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PMID:[Relative sensitivity of various cell cultures to the thermostable exotoxin of B. thuringiensis]. 10 Aug 34

The way in which the lectins concanavalin A (Con A) and Ricinus communis agglutinin (Ricin) alter the K+ content of Ehrlich ascites tumor cells was investigated. Unidrectional and net fluxes were determined in unwashed cells during a time course following lectin addition. Total influx, ouabain sensitive influx, Mg++- and Na+-K+-ATPase activity were all unaffected. Cell ATP content was normal for at least 19 minutes after exposure to Con A. Early after contact with Ricin or Con A efflux was stimulated 2-3-fold, resulting in net K+ loss, but after 20 minutes efflux had returned to normal. Ricin and Con A acted similarly although Ricin was present at only 1/50 the concentration of Con A. When the findings are evaluated together with previous work it is suggested that a particular membrane glycoprotein may be concerned in the efflux alteration observed.
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PMID:Nature of lectin-induced alteration of potassium transfer in Ehrlich ascites tumor cells. 13 11

The inhibition of the proliferation of hyperdiploid Ehrlich ascites tumor cells in suspension cultures by amobarbital is coupled to an increased glycolytic activity as shown by lactic acid production and glucose consumption; higher concentrations of amobarbital than 1 mM enhance the ATP/ADP ratio of the total cell. The actual activity of pyruvate dehydrogenase of intact cells is completely inhibited in the presence of 2 mM amobarbital as was shown by the 14CO2 evolution from [114C]pyruvate or the incorporation of 14CO2 into the total lipid fraction of the cells from [U-14C]lactate. The pyruvate dehydrogenase complex from Ehrlich ascites tumor cells is completely inhibited by 1 mM amobarbital in vitro. The activity of alpha-oxoglutarate dehydrogenase is inhibited by amobarbital, too, as well as shown by measuring the 14CO2 evolution from [1-14C]glutamate with intact cells. It is suggested that the inhibition of pyruvate dehydrogenase in the presence of amobarbital is the result of a direct action on the enzyme as well as the consequence of a change in the cellular redox state or its energy charge.
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PMID:Multiple effects of amobarbital on Ehrlich ascites tumor cells. Inhibition of pyruvate dehydrogenase. 14 57

Ether-permeabilized (nucleotide-permeable) Escherichia coli cells exhibited DNA excision repair when exposed to the following carcinogenic K-region epoxides: 7-methyl- and 7,12-dimethyl-benz[a]anthracene-5,6-oxide, chrysene-5,6-oxide and benzo[a]pyrene-4,5-oxide. This DNA excision repair was missing in uvr A and uvr B mutant cells. The K-region epoxide phenanthrene-9,10-oxide was ineffective in all E. coli strains tested. In contrast to the K-region epoxides which where found active only in wild type cells, 1,2,3,4-diepoxybutane and the 6,7-epoxides of the tumor promoter TPA (12-O-tetradecanoyl-phorbol-13-acetate) elicited DNA repair in uvrA, uvrB mutant cells as well. Enzymic activities catalyzing particular repair steps were identified by determining a) repair polymerization and b) size reduction of denatured DNA. A) An easily quantifiable effect in E. coli wild type cells was epoxide-induced repair polymerization. None of the K-region epoxides tested stimulated DNA repair synthesis in uvrA, uvrB mutant cells, indicating that the uvrA-, uvrB-controlled UV-endonuclease initiated excision repair by cleaving epoxide-damaged DNA. 1,2,3,4-Diepoxybutane and the TPA-6,7-oxides induced DNA repair polymerization in uvr-deficient cells, although to a lesser extent than in wild type cells, suggesting the involvement of uvr-independent incision steps. None of the epoxides induced repair polymerization in a mutant (polA107) lacking the 5'--3'exonucleolytic activity of DNA polymerase I (exonuclease VI). The absence of any repair polymerization in the polA107 mutant indicates that the exonuclease VI plays a central role in removing epoxide-damaged nucleotides. As evidenced by greatly reduced levels of repair polymerization measured in polA1 cells, DNA polymerase I was the main polymerizing enzyme. b) As a consequence of treatment with 7-methyl-benz[a]anthracene-5,6-oxide, DNA from wild type cells, contrary to uvrA mutant cells, showed size reduction after denaturation and sedimentation in alkaline sucrose gradients. This is explained by repair-specific endonucleolytic cleavage of damaged DNA. The incision required the presence of ATP indicating that functional UV-endonuclease needs ATP as a cofactor.
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PMID:Carcinogen-induced DNA repair in nucleotide-permeable Escherichia coli cells. Analysis of DNA repair induced by carcinogenic K-region epoxides and 1,2,3,4-diepoxybutane. 15 97

Ca2+ uptake into Ehrlich ascites tumor cells was studied at 0 degrees C in the presence of mitochondrial inhibitors, conditions that minimized complications caused by sequestration of Ca2+ into organelles or by excretion. Under these conditions Ruthenium Red inhibited Ca2+ uptake, but other previously implicated ions, such as Pi or Mg2+, had no effect. Valinomycin either inhibited or slightly stimulated Ca2+ uptake depending on the presence of excess K+ on the outside or inside of the cell, respectively. Nigericin inhibited Ca2+ transport. Based on these data we propose an electrogenic uptake of Ca2+, possibly via a Ca2+/H+ antiport mechanism. The observation that glucose inhibited Ca2+ uptake suggested that in Ehrlich ascites tumor cells an energy-driven Ca2+ expulsion mechanism is operative, similar to that in erythrocytes. Plasma membrane preparations of ascites tumor cells were found to contain a Ca2+-dependent ATPase. These preparations, when incorporated into liposomes in an inside-out orientation, catalyzed an ATP-dependent uptake of Ca2+.
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PMID:Ca2+ translocation in Ehrlich ascites tumor cells. 15 90

Ehrlich ascites tumor cells containing radioactive ATP were incubated in vitro with a range of concentrations of 2-deoxyglucose in order to produce different rates of ATP catabolism. Concentrations of all radioactive products of ATP catabolism were measured, and apparent rates of adenylate deaminase and inosinate dehydrogenase and of adenylate and inosinate dephosphorylation were calculated. It was concluded that these processes were reggulated primarily by the rate of formation of substrate, and to a lesser extent in some cases, by substrate concentration. No evidence was obtained for regulation of these processes by the concentration of ATP. The deoxyglucose-induced catabolism of radioactive GTP was also studied. When ATP catabolism was induced by incubation with 2,4-dinitrophenol, time courses of accumulation of purine nucleoside monophosphates and rates of alternative pathways of their metabolism were quite different than when deoxyglucose was used.
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PMID:Studies of the regulation of purine nucleotide catabolism. 16 83

The protein kinase activities of a transplantable, insulin-producing hamster islet cell tumor were characterized using gel filtration, sucrose density gradient centrifugation and acrylamide gel electrophoresis. The post-microsomal supernatant fluid contains 70-80% of the protein kinase activity present in crude homogenates. A cAMP-dependent protein kinase, PK I (Mr 170,000), represents 25% of the soluble protein kinase activity assayed with protamine as substrate. It dissociates in the presence of cAMP into a cAMP-binding protein, R2 (Mr 90,000) and a catalytic subunit C (Mr 33,000). The dissociation induced by cAMP seems to be facilitated by the addition of Mg2+ and ATP. The regulatory subunit, R2, changes its gel filtration pattern in the presence of 0.5 M NaCl suggesting dissociation into a smaller subunit, R1 (Mr 44,000). By analogy with purified beef heart protein kinase (Erlichman et al., 1973) and skeletal muscle protein kinase, PK I. The presence in crude homogenates of a free cAMP-binding protein indistinguishable from the R2 derived by dissociation of PK I, suggests that PK I is partially dissociated in vivo. A cAMP-independent (casein) kinase (Mr 210,000) elutes with PK I on columns of Sepharose 6B. Another cAMP-independent protein kinase, PK II (Mr 88,000), is the predominatn form of soluble protein kinase accounting for approximately 75% of the soluble protein kinase activity detected using protaimine as substrate. This cAMP-independent protein kinase changes its gel filtration pattern in the presence of 0.5 M NaCl giving rise to a form which appears to have the same Mr (33,000) as the catalytic subunit of PK I. Studies comparing the catalytic subunit C of PK I with PK II and its salt-induced smaller molecular form demonstrate facile association of C with the cAMP-binding protein of purified bovine heart protein kinase to yield a hybrid holoenzyme, whereas PK II and its smaller form fail to recombine in this fashion. The 33,000 dalton forms derived from PK I (by cAMP) and PK II (by salt) also show different substrate specificities. It would appear, therefore, that pK II is a cAMP-independent protein kinase unrelated to PK I.
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PMID:Characterization of the protein kinases in a transplantable islet cell tumor of the Syrian hamster. 17 65

ACTH stimulated steroidogenesis and cAMP (adenosine 3',5'-monophosphate) accumulation in an adrenocortical mouse tumor cell line (clone Y1) with Kd values which differed by more than one order of magnitude (5.2 X 10(-11) M and 7 X 10(-10) M, respectively). All of the cAMP formed in response to added ACTH appeared extracellularly in 5- or 30-min incubations. ACTH, at 5 and 10 muU/ml, stimulated steroidogenesis to 25% and 40% of maximum activity; and increased the extracellular accumulation of cAMP 1.4-fold and 2.3-fold, respectively. The effects of ACTH appeared to be via an action on intracellular ATP, specific for cAMP and dependent on an ACTH-sensitive adenylate cyclase system. These observations indicate that ACTH increases cAMP accumulation in Y1 cells at virtually all steroidogenic concentrations and suggest that cAMP is an essential component of ACTH-stimulated steroidogenesis.
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PMID:Steroidogenesis and extracellular cAMP accumulation in adrenal tumor cell cultures. 17 21

The activity of purified RNA polymerase II from Novikoff ascites tumor cells is stimulated 5-7-fold by a purified protein factor. This protein factor, designated HLF2, has extensive protein kinase activity and catalyzed the incorporation of gamma-32G from ATP into protein under normal RNA polymerase assay conditions. Protein phosphorylation is totally dependent on the presence of HLF2 and is stimulated 2-3-fold by the presence of highly purified RNA polymerase II. The purification procedure developed for the isolation of the polymerase stimulatory factor resulted in a 4000-fold purification of a protein kinase. Chromatography on carboxymethylcellulose, phosphocellulose, and Sephadex G-100 did not resolve polymerase stimulatory activity from protein kinase activity. Adenylimidodiphosphate (AMP-PNP), an inhibitor of protein kinases, inhibited the stimulatory activity of purified factor by 80%. The heat denaturation profile of protein kinase was paralleled by the loss of polymerase stimulatory activity. Concentrations of (NH4)2SO4 which are known to inhibit polymerase stimulation (Lee and Dahmus, 1973) also inhibit protein kinase activity. The protein kinase activity associated with stimulatory factor catalyzes the phosphorylation of basic proteins such as protamine or histone. The protein kinase is not stimulated by cyclic 3', 5'-AMP or -GMP over a concentration range of 10(-6)-10(-4)M. Furthermore, protein kinase activity is not inhibited by either the regulatory subunit of rabbit muscle protein kinase or by the heat-stable inhibitor of cyclic 3', 5'-AMP-dependent protein kinases. Protein kinase activity is stimulated by KCl or NH4Cl and is inhibited by MnCl2. The apparent Km values, determined in the presence of 4 mM Mg2+, are 0.02 mM for ATP, and 4.1 mM for GTP.
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PMID:Stimulation of ascites tumor RNA polymerase II by protein kinase. 17 56


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