Haeffner E W, Hoffmann C J, Stoehr M, Scherf H
Cancer Res. 1984 Jun;44(6):2668-76.
Ascites tumor cells can be cultivated at a reduced serum concentration if cholesterol (2.50 mg per 100 ml of medium) is added to the culture medium. At serum concentrations of 3%, optimal growth properties are obtained; below 3%, cell cultures usually perish after a few days. Cells grown in the presence of added cholesterol have an elevated content of this molecule per cell as well as in the plasma membrane, and they also show a cholesterol concentration-dependent rate of proliferation. Precursors of the cholesterol-biosynthetic pathway like mevalonic acid, added in mM amounts, or squalene and lanosterol cannot be substituted for cholesterol itself. This is due to the observation that the biosynthetic pathway is blocked at the stage of lanosterol conversion to cholesterol. Cholesterol de novo synthesis from acetate is regulated by the cholesterol content of the cells, which also affects the production of ubiquinone and dolichol. Growth factors such as insulin, prostaglandin F2 alpha, and transferrin added to the medium do not mimic the cholesterol-induced effect. Distribution of DNA during cell cycle and the cell density-dependent reduction in macromolecule synthesis is very similar to the control cells. In contrast, cells without added cholesterol show reduced growth properties accompanied by the accumulation of cells in the mitotic and G2 phase. The cholesterol/phospholipid ratio of the plasma membranes of cholesterol-rich cells is about 15% lower than of the control cells and 40% higher compared to the cholesterol-poor cells, which, however, does not significantly alter the membrane fluidity between the cholesterol-rich and -poor cells as revealed by fluorescence polarization measurements. The most dramatic behavior of the cholesterol-rich cells is their tendency to form aggregates, which is demonstrated either by concanavalin A-induced agglutination or by cell density-dependent aggregation shown by interference microscopy in vivo.
如果在培养基中添加胆固醇（每100毫升培养基2.50毫克），腹水肿瘤细胞可以在降低的血清浓度下培养。在血清浓度为3%时，可获得最佳生长特性；低于3%时，细胞培养物通常在几天后死亡。在添加胆固醇的情况下生长的细胞，每个细胞以及质膜中该分子的含量都会升高，并且它们还表现出胆固醇浓度依赖性的增殖速率。胆固醇生物合成途径的前体，如以毫摩尔量添加的甲羟戊酸、角鲨烯和羊毛甾醇，不能替代胆固醇本身。这是由于观察到生物合成途径在羊毛甾醇转化为胆固醇的阶段被阻断。从乙酸盐从头合成胆固醇受细胞胆固醇含量的调节，这也会影响泛醌和多萜醇的产生。添加到培养基中的生长因子，如胰岛素、前列腺素F2α和转铁蛋白，不会模拟胆固醇诱导的效应。细胞周期中DNA的分布以及大分子合成中细胞密度依赖性的降低与对照细胞非常相似。相比之下，未添加胆固醇的细胞生长特性降低，伴有细胞在有丝分裂期和G2期的积累。富含胆固醇的细胞的质膜胆固醇/磷脂比，比对照细胞低约15%，比胆固醇含量低的细胞高40%，然而，荧光偏振测量显示，这并没有显著改变富含胆固醇和胆固醇含量低的细胞之间的膜流动性。富含胆固醇的细胞最显著的行为是它们形成聚集体的倾向，这通过伴刀豆球蛋白A诱导的凝集或体内干涉显微镜显示的细胞密度依赖性聚集得到证明。
