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At least 937 records · Page 52Linked to original sources
PubMed2004

Enhancement of carcinostatic activity of omega-hydroxy fatty acids by their esterification through increased uptake into tumor cells.

Diverse omega-hydroxy fatty acids (omegaHFAs) and their derivatives were examined for their ability to diminish the cell viability of Ehrlich ascites tumor cells by the mitochondrial dehydrogenase-based WST-1 assay and trypan blue dye exclusion assay. Of the diverse omegaHFAs, hydroxyhexadecanoic acid (omegaH16:0) was appreciably carcinostatic, and hydroxypentadecanoic acid (omegaH15:0) or hydroxypentadecenoic acid (omegaH15:1) was weakly carcinostatic at a dose of 100 micro M, whereas hydroxydodecanoic acid (omegaH12:0) and hydroxyhexadecenoic acid (omegaH16:1) acid were scarcely carcinostatic at the same dose. In contrast their sodium salt derivatives except omegaH16:0 were not carcinostatic. Enhancement of the carcinostatic activity was markedly exerted by ethylesterization of omegaHFAs with the saturated fatty moiety such as omegaH16:0 and omegaH15:0, whereas ethylesters of the unsaturated omegaHFAs such as omegaH15:1 and omegaH16:1 were weakly carcinostatic. Thus intramolecular introduction of a double bond was shown to weaken the carcinostatic activity in case of either omegaHFAs or their ethylester, being in contrast to the conventional knowledge concerning the enhancement of carcinostatic activities of non-hydroxy fatty acids appendant with more double bonds. The intracellular uptake amount of each omegaHFA as quantified by gas chromatography was the following order: omegaH16:0 ethylester (10.1 pg/cell) > omegaH15:0 ethylester (6.4 pg/cell) > omegaH16:0 (3.4 pg/cell) > omegaH15:0 (2.8 pg/cell), which accords with the order of carcinostatic activities of four saturated omegaHFAs in contrast to discord between both the orders for unsaturated omegaHFAs which could be scarcely detected as the intact form within cells. The results indicate that enhancement of carcinostatic activity of omegaH16:0 by ethylesterization was attributed to an appreciable correlation between intracellular uptake amounts and carcinostatic activities for diverse omegaHFAs with saturated fatty moiety, being not true for unsaturated omegaHFAs.

Animals↗
PubMed1991

Cellular internalization, transport, and esterification of iodine-125-NP59 by MA-10 Leydig tumor cells.

The present studies were directed toward understanding the cellular processing of the cholesterol analogue, NP59. NP59 readily entered MA-10 Leydig tumor cells. The cholesterol analogue entered the cells by binding to the plasma membrane and becoming internalized along with plasma membrane cholesterol. Internalized NP59 was readily esterified to NP59 ester. Transport of NP59 within the cell was indistinguishable from transport of cholesterol. Cholesterol and NP59 transport were under the control of cAMP, however, only cholesterol entered the mitochondria and was converted into progesterone. Thus, internalized NP59 could not be removed from the cell by conversion into steroid hormones. Esterified NP59 was metabolically inert and could not be converted back to free NP59 and free fatty acid. Since NP59 was not a substrate for the cholesteryl ester hydrolase, it became trapped in the cell as NP59 ester.

Adosterol↗
PubMed1990

Inhibition of cholesterol synthesis and esterification regulates high density lipoprotein interaction with isolated epithelial cells of human small intestine.

The effect of two inhibitors of 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, lovastatin and monacolin L, and an inhibitor of acyl coenzyme A:cholesterol acyltransferase (ACAT), Sandoz compound 58-035, on the interaction of 125I-labeled high density lipoprotein-3 (HDL3) with isolated human enterocytes was studied. Both HMG-CoA reductase inhibitors inhibited cholesterol synthesis and 125I-labeled HDL3 binding and degradation by enterocytes; a strong correlation between changes in cholesterol synthesis and interaction of 125I-labeled HDL3 with cells was observed. Lovastatin caused reduction of the apparent number of 125I-labeled HDL3 binding sites without affecting the binding affinity. No changes of cell cholesterol content were observed after incubation of cells with lovastatin. Mevalonic acid reversed the effect of lovastatin on 125I-labeled HDL3 binding. Lovastatin blocked up-regulation of the HDL receptor in response to loading of cells with nonlipoprotein cholesterol and modified cholesterol-induced changes of 125I-labeled HDL3 degradation. Lovastatin also reduced HDL-mediated efflux of endogenously synthesized cholesterol from enterocytes. The ACAT inhibitor caused a modest increase of 125I-labeled HDL3 binding to enterocytes and significantly decreased its degradation; both effects correlated with inhibition of cholesteryl ester synthesis. The results allow us to assume that the intracellular free cholesterol pool may play a key role in regulation of the HDL receptor.

Anticholesteremic Agents↗
PubMed1990

Acetyltransferase and sulfotransferase which activate mutagens and carcinogens through O-esterification mechanisms.

The regulatory mechanism of acetyltransferase and sulfotransferase, which are involved in the activation of carcinogenic arylamines and their N-hydroxy derivatives, has been studied. Cytosolic N-acetylation of 2-aminofluorene (2-AF) in hamster liver and skin showed tri-modal distribution in the presence of acetyl CoA, whereas no clear segregation was detected in the N-hydroxyarylacetamide-supported N-acetylation and acetyl CoA-dependent O-acetylation of N-hydroxy-Glu-P-1. From hamster livers, two forms of acetyltransferase, AT-I and AT-II, were purified and characterized to have different catalytic and chemical properties. AT-I was detectable in all the hamsters examined, but AT-II was detected only in the animals showing high rates of 2-AF N-acetylation. Cross-matings of the intra- and inter-phenotypes of three different acetylators (rapid, intermediate, and slow) indicate the genetic inheritance of the arylamine N-acetylation, which follows a Mendelian co-dominant trait. Cytosolic sulfotransferase catalyzes the activation of N-hydroxyarylamines and N-hydroxyarylacetamides through the enzymatic O-sulfonylation. The reaction often shows a sex-related difference in rats. Among three sulfotransferases isolated (HAST I, II, and PST I), the level of HASTs was correlated with the 3'-phosphoadenosine 5'-phosphosulfate (PAPS)-dependent activating capacity of N-hydroxy-2-acetylaminofluorene (N-hydroxy-AAF) in rat livers. In addition, hepatic content of HASTs was decreased by hypophysectomy and restored by the intermittent administration of growth hormone, which mimics the male secretory profile. These results indicate that the sex-related difference in secretory profile of pituitary growth hormone is a major determinant of the male-dominant sulfation in this species.(ABSTRACT TRUNCATED AT 250 WORDS)

2-Acetylaminofluorene↗
PubMed1990

Lipoprotein degradation and cholesterol esterification in primary cell cultures of rabbit atherosclerotic lesions.

Lipoprotein metabolism and cholesterol accumulation in atherosclerotic lesions was studied using enzymatically isolated primary cell cultures from aortas of rabbits made atherosclerotic by cholesterol feeding. The cultures consisted of macrophages and smooth muscle cells, thus resembling, in composition, fatty streak lesions. The mean (+/- SD) cholesteryl ester content of the dispersed cells was 1059 +/- 445 micrograms/mg cell protein, but it declined steeply during 1 week in primary culture. The uptake of low-density lipoprotein (LDL), beta-migrating very low-density lipoprotein (beta-VLDL), and acetylated LDL (acetyl-LDL), labeled with 125I or with the fluorescent probe 1,1'-dioctadecyl-3,3,3',3'- tetramethylindocarbocyanine (DiI), was studied in 2-day-old primary cultures. DiI-acetyl-LDL was avidly taken up by the macrophages and, to a lesser extent, by some smooth muscle cells. The uptake of DiI-beta-VLDL by the macrophages was weaker and less homogeneous than that of DiI-acetyl-LDL. The degradation rates of 125I-labeled beta-VLDL, LDL and acetyl-LDL were 135 +/- 54, 195 +/- 20, and 697 +/- 14 ng/mg cell protein/8 hours, respectively. Incubation with unlabeled acetyl-LDL enhanced the incorporation of [3H]oleate into cholesteryl esters and increased the cellular cholesteryl ester content. These results suggest that arterial macrophages and, to some extent, smooth muscle cells from cholesterol-fed rabbits actively metabolize acetyl-LDL and are thus capable of accumulating cholesteryl esters by uptake of modified forms of LDL.

Animals↗
PubMed1990

The fate of 131I-17-iodoheptadecanoic acid during lactate loading: its oxidation is strongly inhibited in favor of its esterification. A radiochemical study in the canine heart.

The influence of lactate loading on fatty acid metabolism (pH = 7.4) by the normal canine heart was investigated radiochemically using the radioiodinated fatty acid 131I-17-iodoheptadecanoic acid (131I-17-HDA). Fatty acid metabolism was studied during control conditions (n = 8) and after lactate loading (n = 7). In the canine heart total myocardial 131I-17-HDA radioactivity (uptake) was not changed during the lactate intervention. The oxidation decreased fivefold (measured as free 131I-iodide ion) from 70% to 14% (p less than 0.0001, Student's t-test). Thin-layer chromatography of cardiac lipids demonstrated that the non-oxidized 131I-17-HDA was mainly stored in the triglycerides and phosphoglycerides. These results suggest that lactate inhibits cardiac 131I-HDA oxidation.

Animals↗