Effect of 3-Substituted Delta8(14)-15-Ketosterols on Cholesterol Metabolism in Hepatoma Hep G2 Cells

A. F. Kisseleva^1,2, L. E. Goryunova¹, N. V. Medvedeva¹, C. Alquier², and A. Yu. Misharin^1*

¹Institute of Experimental Cardiology, Cardiology Research Center, 3-ya Cherepkovskaya ul. 15a, Moscow, 121552 Russia; fax: (095) 415-2962; E-mail: nmedved@pol.ru

²Laboratory of Human Nutrition (INSERM-U476), av. Mozart 18, 13009 Marseilles, France; fax: (334) 91-75-15-62

^* To whom correspondence should be addressed.

Received July 6, 1998; Revision received December 15, 1998

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The effects of 3-substituted Delta8(14)-15-ketosterols--3beta-(2-hydroxyethoxy)-, 3beta-(2-propenyloxy)-, 3beta-[2(R,S),2,3-oxidopropyloxy]-, 3beta-[2(R,S),2,3-dihydroxypropyloxy]-, 3beta-(2-oxoethoxy)-, 3beta-[2(R,S),2-acetoxy-3-acetamidopropyloxy]-, and 3beta-[2(R,S),2-hydroxy-3-acetamidopropyloxy]-5alpha-cholest-8(14)-en-15-ones--on cholesterol metabolism were studied in human hepatoma Hep G2 cells. 3beta-(2-Propenyloxy)-, 3beta-(2-oxoethoxy)-, and 3beta-[2(R,S),2,3-oxidopropyloxy]-5alpha-cholest-8(14)-en-15-ones inhibited cholesterol biosynthesis without any effect on triglyceride biosynthesis, while 3beta-[2(R,S),2-acetoxy-3-acetamidopropyloxy]- and 3beta-[2(R,S),2-hydroxy-3-acetamidopropyloxy]-5alpha-cholest-8(14)-en-15-ones inhibited both cholesterol biosynthesis and triglyceride biosynthesis at concentrations exceeding 10 µM. 3beta-[2(R,S),2,3-Dihydroxypropyloxy]-5alpha-cholest-8(14)-en-15-one, effectively inhibiting cholesterol biosynthesis, was found also to be toxic in Hep G2 cells at micromolar concentrations. 3beta-[2(R,S),2,3-Oxidopropyloxy]-5alpha-cholest-8(14)-en-15-one effectively inhibited cholesterol acylation. All the tested compounds decreased the HMG-CoA reductase mRNA level at concentrations exceeding 10 µM; however, they did not affect the LDL receptor mRNA level. Among the compounds tested, only 3beta-hydroxy-5alpha-cholest-8(14)-en-15-one decreased the uptake and internalization of LDL-associated cholesteryl esters, being as effective as 25-hydroxycholesterol.

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KEY WORDS: oxysterols, cholesterol metabolism, hepatoma Hep G2 cells

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