洛伐他汀对NB4细胞ras基因p21^(Ras)膜结合作用影响的体外试验

Effects of lovastatin on ras expression and p21^(Ras) membrane localization in human promyelocytic leukemia NB4 cells in vitro

目的 :探讨洛伐他汀 (LOV)对人白血病NB4细胞的作用及其机制。方法 :以MTT比色法首先观察LOV对NB4细胞增殖的影响 ;利用逆转录 -聚合酶链反应半定量测定LOV作用于NB4细胞不同时间H -ras、K -ras、N -ras癌基因mRNA表达水平 ;同时采用流式细胞术测定NB4细胞p2 1Ras总蛋白、膜蛋白的表达。结果 :①LOV抑制NB4细胞增殖 ,IC5 0为 12 5 9μmol/L。②NB4细胞H、K、N -ras基因表达均为阳性。③LOV处理不同时间的NB4细胞H、K、N -ras基因转录水平无明显变化 ;p2 1Ras总蛋白水平也无变化 ,而细胞膜表面p2 1Ras蛋白水平随时间进行性下降。结论 :LOV抑制NB4细胞增殖。LOV靶向HMG -CoA还原酶 ,抑制p2 1Ras蛋白异戊二烯化、阻滞p2 1Ras蛋白与细胞膜结合 ;不影响ras癌基因以及p2 1Ras总蛋白的表达。

AIM: To explore the effects of cholestoral and mevalonate synthesis inhibitor lovastatin (LOV) on the proliferation of NB4 cells and elucidate the mechanisms. METHODS: Cell proliferation was analyzed by MTT assay;the expression of H, K, N- ras oncogenes in NB4 cells at different time point after LOV treatment were determined by semi-quantitative RT-PCR. Both total p21 Ras protein and p21 Ras protein on the cellular membrane were examined by flow cytometry. RESULTS:①LOV inhibited the proliferation of NB4 cells. ②All three kinds of ras were expressed in NB4 cells. ③LOV caused no increase in H, K, N- ras mRNA level. Amount of total p21 Ras protein did not change as the time varied. Concomitantly,p21 Ras protein localized on the cellular membrane decreased. CONCLUSION:LOV inhibits the proliferation of NB4 cells. Targeting HMG-CoA reductase, LOV blocks the isoprenylation of p21 Ras protein which affects its anchorage on the cellular membrane. No change in the H, K, N- ras mRNA and total p21 Ras protein expression is detected.