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)

Dunning hepatoma has a low activity of deoxycytidylate deaminase, comparable to that of normal adult rat liver. This activity seems inconsistent with the rapid proliferation rate of the tumor. Factors which might affect the activity of deoxycytidylate deaminase in the Dunning hepatoma have been examined in it and compared to the Novikoff hepatoma which has high activity of this enzyme. The low activity in Dunning hepatoma does not appear to be the result of any inhibition or, possibly, proteolytic enzyme as judged by mixing experiments, nor does it appear to be due to in vivo differences in nucleotide concentrations especially deoxycytidine 5'-monophosphate, deoxycytidine 5'-triphosphate, or deoxyguanosine 5'-monophosphate which might either help stabilize the enzyme, allosterically increase its activity, or inhibit it. The Dunning hepatoma does not convert cytosine deoxyriboside to uridine deoxyriboside at a significant rate, and the formation of uridine deoxyriboside from deoxyuridine monophosphate is 1% or less during a 30-min incubation of high-speed supernatant fraction from the tumor in either the presence or absence of fluoride. It is concluded that the Dunning hepatoma probably has intrinsically low deoxycytidylate deaminase activity.
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PMID:Factors affecting deoxycytidylate deaminase activity in some transplantable rat hepatomas. 19 66

The activity of deoxycytidylate aminohydrolase, a pivotal enzyme for pyrimidine biosynthesis in mammalian tissue, is 100x greater in the Novikoff hepatoma harvested from the intraperitoneal cavity than in the same tumor excised from either subcutaneous or intramuscular sites. The increased enzyme activity in the intraperitoneal tumor is not due to an increase in protein synthesis, since there are no significant differences in enzyme activity between normal liver, and either the subcutaneous or intramuscular hepatomas. Evidence is presented which indicates that deoxycytidylate aminohydrolase activity, and the expression of alternate pathways of pyrimidine biosynthesis in the Novikoff hepatoma, is dependent on the localization of the tumor within the host.
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PMID:Deoxycytidylate aminohydrolase activity in the Novikoff hepatoma is dependent on the localization of the tumor. 234 70

Activites of the enzymes DNA polymerase, thymidine kinase, thymidylate kinase, thymidylate synthase, and deoxycytidylate deaminase have been measured in rat and human normal and neoplastic liver, in human fetal liver, and in cell lines derived from human hepatomas and rat transplantable hepatomas. The activities of these enzymes were increased in rat transplantable hepatomas, relative to rat normal or host liver, to a degree corresponding to the rapid growth rate of these tumors. With the exception of thymidine kinase, which did not change, the activities of these enzymes increased in human hepatomas relative to the corresponding host liver (apparently normal liver tissue from the same patient) and to human normal liver. The increases in enzyme activity observed in human hepatomas were small in comparison with those found in the rapidly growing rat hepatomas. The activities of deoxycytidylate deaminase in both human and rat liver tissues were 2 to 3 orders of magnitude higher than those of the other enzymes assayed. Activities of the enzymes of DNA synthesis in a slow-growing cell line derived from a human hepatoma were similar to those in human hepatoma tissues. In the case of rapidly growing cell lines derived from rat and human hepatomas, enzyme activities were higher than those in the corresponding tissues.
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PMID:Activities of some enzymes of pyrimidine and DNA synthesis in a rat transplantable hepatoma and human primary hepatomas, in cell lines derived from these tissues, and in human fetal liver. 624 89