Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0019204 (hepatocellular carcinoma)
 71,386 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

1. Incubation of human and rat hepatoma cells with insulin (1 mU/10(6) cells) decreases their content of adenosine 3':5'-monophosphate by more than half after 1 h and by about a quarter after 4 h. 2. The activities of the ATP-metabolising enzymes, adenylate kinase and Mg2+-adenosine triphosphatase are significantly increased by insulin within 1 h and after 4 h. Activity of succinate dehydrogenase and lactic dehydrogenase showed no change at either time interval. 3. Insulin markedly stimulated glucose 6-phosphate dehydrogenase activity within 1 h but by 4 h the increase was less apparent. Glutamate dehydrogenase activity by contrast was not increased by 1 h but was elevated at 4 h.
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PMID:The influence of insulin on various enzyme activities in human and rat hepatoma cells. 17 8

Adenylate kinases, purified from adult rat liver and skeletal muscle and from a fast growing hepatoma, were examined in the presence of a series of prostaglandins. Prostaglandins A1, A2, E1, E2 and F2alpha stimulated liver adenylate kinase 27% to 149%. All of these protaglandins stimulated the skeletal muscle enzyme from 47% to 82%. While prostaglandins A2 and E2 stimulated, prostaglandins A1 and F2alpha inhibited, and prostaglandin E1 was without effect on the hepatoma adenylate kinase.
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PMID:Prostaglandin regulation of adenylate kinases purifed from liver, skeletal muscle, and hepatoma. 18 63

DNA polymerase-beta was purified from Novikoff hepatoma and used as an antigen in an in vitro immunization system to produce monoclonal antibodies. These reagents surprisingly showed cross-reactivity to a number of proteins, including several DNA polymerases. Nearly all of these proteins possess nucleotide binding sites, which suggested the potential value of using the monoclonals to elucidate structure-function relationships within polymerase-beta. Furthermore, these antibodies were able to partially neutralize (40-50%) polymerase-beta activity, and this effect could be blocked by dNTP1 but not by dNMP or rNTP. The limited neutralization phenomenon is at least partially explained by the weak binding affinity of these antibodies. Scatchard analysis of immunoprecipitation data predicted a Kd of 1.8 x 10(-8) M. Epitope mapping studies showed that the region of polymerase-beta recognized by one of the monoclonal antibodies is within residues 235-335, and sequence homology studies indicated that the epitope is probably located in the region of amino acids 283-320. At least a portion of this area, namely residues 301-308 and 311-315, appears to be part of a nucleotide binding domain which has sequence homology with a portion of the highly conserved ATP binding site in adenylate kinase.
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PMID:Structure-function analysis of DNA polymerase-beta using monoclonal antibodies: identification of a putative nucleotide binding domain. 138 Aug 29

It has been proposed that hexokinase bound to mitochondria occupies a preferred site to which ATP from oxidative phosphorylation is channeled directly (Bessman, S. (1966) Am. J. Medicine 40, 740-749). We have investigated this problem in isolated Zajdela hepatoma mitochondria. Addition of ADP to well-coupled mitochondria in the presence of an oxidizable substrate initiates the synthesis of glucose 6-phosphate via bound hexokinase. This reaction is only partially inhibited by oligomycin, carboxyatractyloside, carbonyl cyanide m-chlorophenylhydrazone (CCCP) or any combination of these, suggesting a source of ATP in addition to oxidative phosPhorylation. This source appears to be adenylate kinase, since Ado2P5, an inhibitor of the enzyme, suppresses hexokinase activity by about 50% when added alone or suppresses activity completely when added together with any of the inhibitors of oxidative phosphorylation. Ado2P5 does not uncouple oxidative phosphorylation nor does it inhibit ADP transport (state 3 respiration) or hexokinase. The relative amount of ATP contributed by adenylate kinase is dependent upon the ADP concentration. At low ADP concentrations, glucose phosphorylation is supported by oxidative phosphorylation, but as the adenine nucleotide translocator becomes saturated the ATP contributed by adenylate kinase increases due to the higher apparent Km of the enzyme. Under conditions of our standard experiment ([ADP] = 0.5 mM), adenylate kinase provides about 50% of the ATP used by hexokinase in well-coupled mitochondria. In spite of this, externally added ATP supported higher initial rates of hexokinase activity than ADP. Our findings demonstrate that oxidative phosphorylation is not a specific or preferential source of ATP for hexokinase bound to hepatoma mitochondria. The apparent lack of a channeling mechanism for ATP to hexokinase in these mitochondria is discussed.
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PMID:Adenylate kinase is a source of ATP for tumor mitochondrial hexokinase. 299 May 72

Mitochondrial ATPase and adenylate kinase activity of hepatoma cells were inhibited by hematoporphyrin derivative (HPD) followed by photoirradiation. Inhibition of ATPase activity was a dose- and time-related event. Malonaldehyde (MDA) content of mitochondrial membranes was markedly increased by HPD plus light. The content of mouse liver microsomal cytochrome P-450 was greatly increased after intraperitoneal injection of HPD for 4 days (5 mg/kg/day). The liver weight, and levels of liver microsomal G-6-phosphatase, MDA and triglyceride (TG) showed no difference in treated vs. control animals. The data presented here demonstrate that mitochondria may be a sensitive site of action of HPD photosensitization, and inactivation of ATPase and adenylate kinase may be an important contributing factor to tumor cell damage and death.
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PMID:Photosensitization of mitochondrial adenosine-triphosphatase and adenylate kinase by hematoporphyrin derivative in vitro. 300 50

Monosubstituted derivatives of adenosine 5'-phosphate (AMP) with substituents of 1-3 atoms or group replacements at any of 11 positions have been synthesized and examined as substrates and inhibitors of the rat muscle adenylate kinase isozyme (AK-M), and the rat AK II and III isozymes predominant in poorly differentiated hepatoma tissue and normal liver tissue, respectively. Inhibition indexes of the compounds were expressed as KM (AMP)/Ki for competitive inhibition or as KM (AMP)/KM when only KM was available. Substituents at N(1), N6, or C(8) or on ionizable phosphate oxygen reduced inhibition below measurable levels; 2'-deoxy-AMP and adenosine 5'-sulfate had identical inhibition indexes with all three isozymes; compounds with substituents at C(2), O(2'), O(3'), C(4'), C(5'), or O(5') had higher inhibition indexes with AK-M than with AK II or III and the same or similar indexes for AK II and III. The most effective and/or selective inhibitors were 2-NHMe-AMP (index with AK-M, 0.2; index ratio, AK-M/AK III, 9.1), 2'-O-Me-AMP (index with AK-M, 0.14; index ratio, AK-M/AK III, 8.2), 2',3'-O-CMe2-AMP (index with AK-M, 0.25; index ratio, AK-M/AK II, 6.6), 4'-allyl-AMP (index with AK-M, 0.97; index ratio, AK-M/AK III, 8.1), and 5'(S)-Et-AMP (index with AK-M, 0.64; index ratio, AK-M/AK II, 11.2). The study provides additional evidence that the attachment of simple substituents to various atoms in turn of a substrate is a potentially useful approach in early stages of the attempted design of isozyme-selective inhibitors.
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PMID:Species- or isozyme-specific enzyme inhibitors. 7. Selective effects in inhibitions of rat adenylate kinase isozymes by adenosine 5'-phosphate derivatives. 628 70

Oxygen is an important regulator of gene expression in mammalian cells, though the extent of operation and the organization of the inducible mechanisms involved are still largely undetermined. To define better the response to hypoxia, we have used differential display PCR to identify genes whose expression is induced in HeLa cells exposed to 1% oxygen. Among six genes whose induction by hypoxia was newly defined in this way, three were of known function, encoding the glucose transporter isoform 3 (Glut-3), adenylate kinase isoenzyme 3 (AK-3), and tissue factor, two were expressed sequence tags (ESTs), and one corresponded to a new sequence. One regulator of the transcriptional response to hypoxia has recently been identified as a heterodimeric DNA-binding complex termed hypoxia-inducible factor-1 (HIF-1), which is also inducible by the iron chelator, desferrioxamine. Of the six hypoxically regulated genes, at least four were also induced by exposure of the cells to desferrioxamine. To analyse further the mechanisms underlying induction of the genes identified in the differential display, inducible expression was compared in wild-type mouse hepatoma cells (Hepa-1), and mutant derivatives (c4) which fail to generate HIF-1, due to a functional defect in one component, HIF-1 beta. Two types of response were defined. For Glut-3 and AK-3, mutant (c4) cells showed almost complete loss of the inducible response to both hypoxia and desferrioxamine. In contrast, tissue factor mRNA was more inducible by both stimuli in c4 than wild-type cells. These studies demonstrate the critical importance of HIF-1 beta in newly recognized responses to hypoxia, and provide further evidence of the importance of this system of gene regulation in mammalian cells; they also demonstrate responses to both hypoxia and desferrioxamine which are independent of HIF-1 beta and which appear exaggerated in HIF-1 beta-deficient cells.
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PMID:Identification of hypoxically inducible mRNAs in HeLa cells using differential-display PCR. Role of hypoxia-inducible factor-1. 891 36