| Carbamyl phosphate synthetases in rat liver neoplasms. | |
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MedLine Citation:
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PMID: 162860 Owner: NLM Status: MEDLINE |
Abstract/OtherAbstract:
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Isozymes of carbamyl phosphate synthetase (CPS), CPS I, a mitochondrial enzyme found exclusively in liver and involved in urea synthesis, and of CPS II, a soluble cytoplasmic enzyme widely distributed in animal tissues, were assayed in rat liver and in a series of rat liver neoplasms ranging widely in growth rate and degree of differentiation. CPS I was absent from fast-growing, poorly differentiated hepatomas, such as the Novikoff hepatoma and Morris hepatomas 3924A and 9098F, but was present in slow-growing, well- and highly differentiated Morris hepatomas. However, there was no close correlation between the growth rate or degree of differentiation and the CPS I activity. Activity was very high, at levels comparable with normal liver at about 9 UNITS/G, IN SLOW-GROWING, HEPATOMAS 21, 47C, and 28A but was very low in other slow-growing highly differentiated hepatomas 9618A, 66, and 16. CPS II activity was present in normal liver and all hepatomas examined, but with very low activity, of the order of 1% or less of that of CPS I activity, with maximal values at 5 to 70 milliunits/g. Again, there was no clear correlation with growth rate; the activity was lowest in fast-growing, poorly differentiated hepatomas. A striking observation was a marked lowering of CPS I activity in livers of rats bearing large, slow-growing tumors that have high CPS I activity. As the tumors grew larger and the liver CPS I decreased, a relatively constant total CPS I activity was maintained, suggesting the existence of a homeostatic mechanism. The effect was not observed in rats bearing either fast-growing hepatomas or slow-growing hepatomas with low CPS I activity and was not due to some specific nutritional effects of the tumor on the host. |
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Authors:
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D Lawson; W K Paik; H P Morris; S Weinhouse |
Publication Detail:
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Type: Journal Article; Research Support, U.S. Gov't, P.H.S. |
Journal Detail:
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Title: Cancer research Volume: 35 ISSN: 0008-5472 ISO Abbreviation: Cancer Res. Publication Date: 1975 Jan |
Date Detail:
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Created Date: 1975-04-16 Completed Date: 1975-04-16 Revised Date: 2006-11-15 |
Medline Journal Info:
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Nlm Unique ID: 2984705R Medline TA: Cancer Res Country: UNITED STATES |
Other Details:
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Languages: eng Pagination: 156-63 Citation Subset: IM |
Export Citation:
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APA/MLA Format Download EndNote Download BibTex |
| MeSH Terms | |
Descriptor/Qualifier:
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Animals Carbamates Carbon Radioisotopes Carcinoma, Hepatocellular / analysis, enzymology* Cell Division Cell Fractionation Fasting Isoenzymes / metabolism Liver / enzymology* Liver Neoplasms / analysis, enzymology* Male Neoplasms, Experimental / analysis, enzymology Phosphotransferases / analysis, metabolism* Rats |
| Chemical | |
Reg. No./Substance:
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0/Carbamates; 0/Carbon Radioisotopes; 0/Isoenzymes; EC 2.7.-/Phosphotransferases |
From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine
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