The intracellular transport of low density lipoprotein-derived cholesterol is inhibited in Chinese hamster ovary cells cultured with 3-beta-[2-(diethylamino)ethoxy]androst-5-en-17-one.
In mammalian cells, low density lipoprotein (LDL) is bound, internalized, and delivered to lysosomes where LDL-cholesteryl esters are hydrolyzed to unesterified cholesterol. The mechanisms of intracellular transport of LDL-cholesterol from lysosomes to other cellular sites and LDL-mediated regulation of cellular cholesterol metabolism are unknown. We have identified a pharmacological agent, U18666A (3-beta-[2-diethyl-amino)ethoxy]androst-5-en-17-one), which impairs the intracellular transport of LDL-derived cholesterol in cultured Chinese hamster ovary (CHO) cells. U18666A blocks the ability of LDL-derived cholesterol to stimulate cholesterol esterification, and to suppress 3-hydroxy-3-methylglutaryl-coenzyme A reductase and LDL receptor activities. However, U18666A does not impair 25-hydroxycholesterol-mediated regulation of these processes. In addition, U18666A impedes the ability of LDL-derived cholesterol to support the growth of CHO cells. However, U18666A has only moderate effects on growth supported by non-lipoprotein cholesterol. LDL binding, internalization, and lysosomal hydrolysis of LDL-cholesteryl esters are not affected by the presence of U18666A. Analysis of intracellular cholesterol transport reveals that LDL-derived cholesterol accumulates in the lysosomes of U18666A-treated CHO cells which results in impaired movement of LDL-derived cholesterol to other cell membranes.
Liscum
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Department of Physiology, Tufts University School of Medicine, Boston, Massachusetts 02111.
Faust
J R
JR
D000736:Androstenes / Q000494:pharmacology*; D000818:Animals; D000924:Anticholesteremic Agents / Q000494:pharmacology*; D001692:Biological Transport; D002460:Cell Line; D002462:Cell Membrane / Q000378:metabolism; D008078:Cholesterol, LDL / Q000037:antagonists & inhibitors / Q000378:metabolism*; D006224:Cricetinae; D003412:Cricetulus; D003864:Depression, Chemical; D006868:Hydrolysis; D006888:Hydroxycholesterols / Q000378:metabolism; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D025782:Hydroxymethylglutaryl-CoA-Reductases, NADP-dependent; D011973:Receptors, LDL / Q000378:metabolism
D000736:Androstenes; D000924:Anticholesteremic Agents; D008078:Cholesterol, LDL; D006888:Hydroxycholesterols; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D011973:Receptors, LDL; C006261:3-beta-(2-(diethylamino)ethoxy)androst-5-en-17-one; C007997:25-hydroxycholesterol; D025782:Hydroxymethylglutaryl-CoA-Reductases, NADP-dependent