Suppression of 3-hydroxy-3-methylglutaryl coenzyme A reductase activity and inhibition of growth of human fibroblasts by 7-ketocholesterol.
Suppression of 3-hydroxy-3-methylglutaryl coenzyme A reductase activity and inhibition of growth of human fibroblasts by 7-ketocholesterol.
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DOI：
10.1016/s0021-9258(19)42106-6
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发表时间：
1974-11
期刊：
影响因子：
--
通讯作者：
M. Brown;J. Goldstein
中科院分区：
文献类型：
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作者：
M. Brown;J. Goldstein
在47种类固醇化合物中，有11种化合物抑制培养的人成纤维细胞中3-羟基-3-甲基戊二酰辅酶A还原酶活性的能力比胆固醇更强。抑制酶活性的唯一一致的结构要求是在甾醇核的3位存在未酯化的氧官能团。在位置6、7或25处酮或羟基的存在显著增强抑制活性。在来自患有家族性高胆固醇血症的纯合子的成纤维细胞中，这些成纤维细胞在遗传上对低密度脂蛋白中所含胆固醇的生理酶抑制具有抵抗力，非脂蛋白类固醇对3-羟基-3-甲基戊二酰辅酶A还原酶活性的抑制程度与正常细胞相同。7-酮基胆固醇，这是100倍，比胆固醇更有效的重量基础上，抑制酶活性在正常细胞超过90%，在2小时内。这种抑制反映在一个类似的显着减少的乙酸，但不是甲羟戊酸到毛地黄皂苷可沉淀的sterols.When正常细胞培养在7-ketocholesterol的存在下，但在没有脂蛋白的情况下，内源性胆固醇合成的抑制7-ketocholesterol导致细胞生长的显着抑制率。这种生长抑制被阻止在培养基中的胆固醇或甲羟戊酸，但不是乙酸的存在。因此，3-羟基-3-甲基戊二酰辅酶A还原酶的活性成为胆固醇生成和成纤维细胞生长的限速因子，在此条件下，外源性胆固醇不可用的细胞。它的结论是，7-酮胆固醇可以提供一个强大的工具，描绘的机制，胆固醇和其他类固醇促进人类细胞的生长培养。
Of 47 steroid compounds tested for their ability to suppress 3-hydroxy-3-methylglutaryl coenzyme A reductase activity in cultured human fibroblasts, 11 were more potent than cholesterol. The only consistent structural requirement for suppression of enzyme activity was the presence of an unesterified oxygen function at position 3 of the sterol nucleus. The presence of a ketone or hydroxyl group at positions 6, 7, or 25 markedly enhanced inhibitory activity. In fibroblasts from a homozygote with familial hypercholesterolemia, which are genetically resistant to physiological enzyme suppression by cholesterol contained in low density lipoproteins, 3-hydroxy-3-methylglutaryl coenzyme A reductase activity was suppressed by nonlipoprotein steroids to the same degree as in normal cells. 7-Ketocholesterol, which was 100 times more potent than cholesterol on a weight basis, suppressed enzyme activity in normal cells by more than 90% in 2 hours. This inhibition was reflected in a similarly marked decrease in the rate of incorporation of acetate, but not mevalonate into digitonin-precipitable sterols.When normal cells were cultured in the presence of 7-ketocholesterol but in the absence of lipoproteins, the suppression of endogenous cholesterol synthesis by 7-ketocholesterol resulted in a marked inhibition of cell growth. This inhibition of growth was prevented by the presence in the culture medium of either cholesterol or mevalonate, but not acetate. Thus, the activity of 3-hydroxy-3-methylglutaryl coenzyme A reductase became the rate-limiting factor both for cholesterogenesis and for growth of fibroblasts under conditions where exogenous cholesterol was not available to the cells. It is concluded that 7-ketocholesterol may provide a powerful tool for delineation of the mechanism by which cholesterol and other steroids promote the growth of human cells in culture.