Department of Pharmacology, Shenyang Pharmaceutical University, Shenyang, China.
Cancer Biol Ther. 2010 Jan;9(2):96-108. doi: 10.4161/cbt.9.2.10287. Epub 2010 Jan 9.
The antiproliferative effects and apoptosis inducing abilities of four 18beta-glycyrrhetinic acid (GA) derivatives, methyl 2-cyano-3,11-dioxooleana-1,12-dien-30-oate (CDODO-Me-11), methyl 2-cyano-3,12-dioxooleana-1,12-dien-30-oate (CDODO-Me-12) and their non-esters were investigated in human leukemia cells. Methyl esterification and switching a keto group from position C(11) to C(12) significantly increased the antiproliferative effects. CDODO-Me-11 and CDODO-Me-12 were 10-fold more potent than their non-esters, respectively. CDODO-Me-12 was 10-fold more effective than CDODO-Me-11 in inducing apoptosis which was correlated with the activation of caspase-8 and caspase-9. Western blot analyses revealed that CDODO-Me-12 and CDODO-Me-11 downregulated the levels of anti-apoptosis proteins, c-FLIP, XIAP and Mcl-1, without altering the protein levels of Bcl-2 and the death receptors DR4 and DR5. Both agents decreased the levels of the mitochondrial membrane potential without altering the intracellular H(2)O(2) levels. Jurkat cells without expression of caspase-8 were not sensitive to CDODO-Me-12, but were somewhat responsive to CDODO-Me-11. K562 cells with higher intracellular reduced glutathione (GSH ) levels were less responsive to CDODO-Me-12 apoptosis induction than U937 cells even though both cell lines were equally sensitive to CDODO-Me-11 apoptosis induction. Both agents depleted intracellular GSH levels and exogenous GSH reversed apoptosis induction by either agent in HL-60 cells. N-acetylcysteine (NAC) significantly attenuated apoptosis induction by CDODO-Me-12, but only weakly, that by CDODO-Me-11. UV spectrophotometric analysis revealed that both agents interacted with GSH while only CDODO-Me-12 had high reactivity with NAC. These data suggest that both agents induce apoptosis requiring to bind to functional proteins with thiol groups and that GSH may play a protective role by forming inactive adducts with them.
四种 18β-甘草次酸（GA）衍生物，即甲基 2-氰基-3,11-二氧代齐墩果-1,12-二烯-30-酸甲酯（CDODO-Me-11）、甲基 2-氰基-3,12-二氧代齐墩果-1,12-二烯-30-酸甲酯（CDODO-Me-12）及其非酯类化合物在人白血病细胞中的抗增殖作用和诱导凋亡能力进行了研究。甲酯化和将酮基从 C（11）位转换到 C（12）位显著增强了抗增殖作用。CDODO-Me-11 和 CDODO-Me-12 分别比它们的非酯类化合物强 10 倍。CDODO-Me-12 在诱导凋亡方面比 CDODO-Me-11 有效 10 倍，这与 caspase-8 和 caspase-9 的激活有关。Western blot 分析表明，CDODO-Me-12 和 CDODO-Me-11 下调了抗凋亡蛋白 c-FLIP、XIAP 和 Mcl-1 的水平，而不改变 Bcl-2 和死亡受体 DR4 和 DR5 的蛋白水平。两种药物均降低了线粒体膜电位水平，而不改变细胞内 H2O2 水平。没有 caspase-8 表达的 Jurkat 细胞对 CDODO-Me-12 不敏感，但对 CDODO-Me-11 有一定反应。与 U937 细胞相比，具有较高细胞内还原型谷胱甘肽（GSH）水平的 K562 细胞对 CDODO-Me-12 诱导凋亡的反应性较低，尽管两种细胞系对 CDODO-Me-11 诱导凋亡的反应性相同。两种药物均耗尽细胞内 GSH 水平，外源性 GSH 逆转了 HL-60 细胞中任何一种药物诱导的凋亡。N-乙酰半胱氨酸（NAC）显著减弱了 CDODO-Me-12 诱导的凋亡，但对 CDODO-Me-11 的作用较弱。紫外分光光度分析表明，两种药物均与 GSH 相互作用，而只有 CDODO-Me-12 与 NAC 具有高反应性。这些数据表明，两种药物均通过与具有巯基的功能蛋白结合诱导凋亡，GSH 可能通过与它们形成无活性的加合物来发挥保护作用。
