Effect of FR194738, a potent inhibitor of squalene epoxidase, on cholesterol metabolism in HepG2 cells.
(E)-N-ethyl-N-(6,6-dimethyl-2-hepten-4-ynyl)-3-[2-methyl-2-(3-thienylmethoxy)propyloxy]benzylamine hydrochloride (FR194738) inhibited squalene epoxidase activity in HepG2 cell homogenates with an IC50 value of 9.8 nM. In the study using intact HepG2 cells, FR194738 inhibited cholesterol synthesis from [14C]acetate with an IC50 value of 4.9 nM, and induced intracellular [14C]squalene accumulation. On the other hand, the 3-hydroxy-3-methylglutaryl (HMG)-CoA reductase inhibitor simvastatin reduced both cholesterol and squalene synthesis from [14C]acetate. Incubation with simvastatin for 18 h produced increases in HMG-CoA reductase activity in HepG2 cells, which was related to the degree of reduction in cholesterol synthesis. The HMG-CoA reductase activity increased by 13- and 19-fold at the concentrations of simvastatin that inhibited cholesterol synthesis by 65% and 82%, respectively. In contrast, FR194738 did not increase HMG-CoA reductase activity at the concentrations that inhibited cholesterol synthesis by 24% and 69%, and moderate increase (4.6-fold) was observed at the concentration that inhibited cholesterol synthesis by 90%. These results suggest that non-sterol metabolite(s) derived from mevalonate prior to the squalene epoxidation step in the cholesterol synthetic cascade have a regulatory role in the suppression of HMG-CoA reductase activity. We speculate that FR194738 inhibits cholesterol synthesis with a minimal change of the regulator(s) and would be highly effective in the treatment of hypercholesterolemia.
Sawada
M
M
Medicinal Biology Research Laboratories, Fujisawa Pharmaceutical Co., Ltd., 1-6, Kashima 2-chome, Osaka 532-8514, Yodogawa, Japan. masae_sawada@po.fujisawa.co.jp
Matsuo
M
M
Hagihara
H
H
Tenda
N
N
Nagayoshi
A
A
Okumura
H
H
Washizuka
K
K
Seki
J
J
Goto
T
T
D001596:Benzylamines / Q000494:pharmacology*; D002784:Cholesterol / Q000096:biosynthesis / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D006801:Humans; D006903:Hydroxymethylglutaryl CoA Reductases / Q000302:isolation & purification / Q000378:metabolism; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000494:pharmacology; D015394:Molecular Structure; D010105:Oxygenases / Q000037:antagonists & inhibitors*; D019821:Simvastatin / Q000031:analogs & derivatives* / Q000494:pharmacology; D013185:Squalene / Q000378:metabolism; D050603:Squalene Monooxygenase; D014407:Tumor Cells, Cultured
D001596:Benzylamines; D004791:Enzyme Inhibitors; C443179:FR 194738; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors; D013185:Squalene; D002784:Cholesterol; C063287:simvastatin acid; D019821:Simvastatin; D006903:Hydroxymethylglutaryl CoA Reductases; D010105:Oxygenases; D050603:Squalene Monooxygenase