Zhong Wen-Bin, Wang Chih-Yuan, Chang Tien-Chun, Lee Wen-Sen
Graduate Institute of Physiology, College of Medicine, National Taiwan University, Taipei 110, Taiwan.
Endocrinology. 2003 Sep;144(9):3852-9. doi: 10.1210/en.2003-0098.
Lovastatin has been used to treat hypercholesterolemia through blocking the mevalonate biosynthesis pathway. Inhibition of mevalonate synthesis may result in antiproliferation and cell apoptosis. The aim of the present study was to examine the apoptotic effect of lovastatin in human ARO cells and delineate its underlying molecular mechanism. Our results showed that lovastatin dose- and time-dependently induced apoptosis in ARO cells. Pretreatment with cycloheximide dose-dependently suppressed lovastatin-induced apoptosis, suggesting that de novo protein synthesis is required for lovastatin effect on the induction of apoptosis in ARO cells. Treatment of the cells with 50 microM lovastatin induced cytochrome c translocation from mitochondria to cytosol; increases in caspase-2, -3, and -9 activity; and poly (ADP-ribose) polymerase degradation in a time-dependent manner. However, administration of mevalonate or geranylgeraniol, but not farnesol, dose-dependently prevented lovastatin-induced poly (ADP-ribose) polymerase degradation and the occurrence of apoptosis, but treatment with geranylgeranyl transferase inhibitor, GGTI-298, which blocks the geranylgeranylation, induced an increase in the percentage of the apoptotic cells. These data suggest that geranylgeranylation is required for survival of the lovastatin-treated ARO cells. To support this notion, we demonstrate that lovastatin dose-dependently decreased the translocation of RhoA and Rac1, but not Ras, from cytosol to membrane fraction. Moreover, the lovastatin-induced translocation inhibitions in RhoA and Rac1 were prevented by mevalonate and geranylgeraniol but not farnesol. In conclusion, our data suggest that lovastatin induced apoptosis in ARO cells by inhibiting protein geranylgeranylation of the Rho family but not farnesylation of the Ras family.
洛伐他汀已被用于通过阻断甲羟戊酸生物合成途径来治疗高胆固醇血症。抑制甲羟戊酸合成可能导致细胞增殖抑制和凋亡。本研究的目的是检测洛伐他汀对人ARO细胞的凋亡作用，并阐明其潜在的分子机制。我们的结果表明，洛伐他汀在ARO细胞中呈剂量和时间依赖性地诱导凋亡。用环己酰亚胺预处理呈剂量依赖性地抑制洛伐他汀诱导的凋亡，这表明从头合成蛋白质是洛伐他汀对ARO细胞诱导凋亡作用所必需的。用50微摩尔/升洛伐他汀处理细胞会导致细胞色素c从线粒体转位至胞质溶胶；半胱天冬酶-2、-3和-9的活性增加；以及聚（ADP-核糖）聚合酶以时间依赖性方式降解。然而，给予甲羟戊酸或香叶基香叶醇，但不是法尼基醇，呈剂量依赖性地阻止了洛伐他汀诱导的聚（ADP-核糖）聚合酶降解和凋亡的发生，但是用香叶基香叶基转移酶抑制剂GGTI-298处理，其阻断香叶基香叶基化，会导致凋亡细胞百分比增加。这些数据表明香叶基香叶基化是洛伐他汀处理的ARO细胞存活所必需的。为支持这一观点，我们证明洛伐他汀呈剂量依赖性地减少RhoA和Rac1从胞质溶胶向膜组分的转位，但不影响Ras的转位。此外，甲羟戊酸和香叶基香叶醇可阻止洛伐他汀诱导的RhoA和Rac1转位抑制，但法尼基醇则不能。总之，我们的数据表明，洛伐他汀通过抑制Rho家族的蛋白质香叶基香叶基化而不是Ras家族的法尼基化来诱导ARO细胞凋亡。
