PDF(Pubmed)
Abstract：
Aim: This study aimed to decipher the molecular mechanism underlying the synergistic effect of inhibitors of the mevalonate-cholesterol pathway (i.e., statins) and aminopeptidase inhibitors (APis) on APi-sensitive and -resistant acute myeloid leukemia (AML) cells. Methods: U937 cells and their sublines with low and high levels of acquired resistance to (6S)-[(R)-2-((S)-Hydroxy-hydroxycarbamoyl-methoxy-methyl)-4-methyl-pentanoylamino]-3,3 dimethyl-butyric acid cyclopentyl ester (CHR2863), an APi prodrug, served as main AML cell line models. Drug combination effects were assessed with CHR2863 and in vitro non-toxic concentrations of various statins upon cell growth inhibition, cell cycle effects, and apoptosis induction. Mechanistic studies involved analysis of Rheb prenylation required for mTOR activation. Results: A strong synergy of CHR2863 with the statins simvastatin, fluvastatin, lovastatin, and pravastatin was demonstrated in U937 cells and two CHR2863-resistant sublines. This potent synergy between simvastatin and CHR2863 was also observed with a series of other human AML cell lines (e.g., THP1, MV4-11, and KG1), but not with acute lymphocytic leukemia or multiple solid tumor cell lines. This synergistic activity was: (i) specific for APis (e.g., CHR2863 and Bestatin), rather than for other cytotoxic agents; and (ii) corroborated by enhanced induction of apoptosis and cell cycle arrest which increased the sub-G1 fraction. Consistently, statin potentiation of CHR2863 activity was abrogated by co-administration of mevalonate and/or farnesyl pyrophosphate, suggesting the involvement of protein prenylation; this was experimentally confirmed by impaired Rheb prenylation by simvastatin. Conclusion: These novel findings suggest that the combined inhibitory effect of impaired Rheb prenylation and CHR2863-dependent mTOR inhibition instigates a potent synergistic inhibition of statins and APis on human AML cells.
摘要：
目的：本研究旨在破译甲羟戊酸-胆固醇途径抑制剂协同作用的分子机制（即，他汀类药物）和氨肽酶抑制剂（APis）对APi敏感和耐药的急性髓系白血病（AML）细胞。方法：U937细胞及其亚系对（6S）-[（R）-2-（（S）-羟基-羟基氨基甲酰基-甲氧基-甲基）-4-甲基-戊酰基氨基]-3,3二甲基-丁酸环戊酯（CHR2863）具有低和高水平的获得性抗性，APi前药，作为主要的AML细胞系模型。使用CHR2863和体外无毒浓度的各种他汀类药物在细胞生长抑制后评估药物组合效果。细胞周期效应，和凋亡诱导。机制研究涉及mTOR活化所需的Rheb戊烯化的分析。结果：CHR2863与他汀类药物辛伐他汀有很强的协同作用，氟伐他汀,洛伐他汀,普伐他汀在U937细胞和两个CHR2863耐药亚系中得到证实。在一系列其他人类AML细胞系中也观察到辛伐他汀和CHR2863之间的这种有效协同作用（例如，THP1、MV4-11和KG1)，但不是急性淋巴细胞白血病或多种实体瘤细胞系。这种协同活性是：（i）对APis具有特异性（例如，CHR2863和Bestatin)，而不是其他细胞毒性剂；（ii）通过增强诱导凋亡和细胞周期停滞来证实，这增加了亚G1级。始终如一，甲羟戊酸和/或焦磷酸法尼酯的共同给药消除了他汀类药物对CHR2863活性的增强作用，提示参与蛋白质异戊二烯化；辛伐他汀受损的Rheb异戊二烯化实验证实了这一点。结论：这些新发现表明，受损的Rheb戊烯化和CHR2863依赖性mTOR抑制的联合抑制作用激发了他汀类药物和APis对人AML细胞的有效协同抑制。
