洛伐他汀对NB4细胞ras基因p21Ras膜结合作用影响的体外试验

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p21^Ras总蛋白、膜蛋白的表达。结果:①LOV抑制NB4细胞增殖,IC50为12.59μmol/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;p21^Ras总蛋白水平也无变化,而细胞膜表面p21^Ras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p21^Ras蛋白异戊二烯化、阻滞p21^Ras蛋白与细胞膜结合;不影响ras癌基因以及p21^Ras总蛋白的表达。

Effects of lovastatin on ras expression and p21Ras membrane localization in human promyelocytic leukemia NB4 cells in vitro

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.