Li Hongyu, Li Manmei, Wang Guocai, Shao Fangyuan, Chen Wenbo, Xia Chao, Wang Sheng, Li Yaolan, Zhou Guangxiong, Liu Zhong
Institute of Traditional Chinese Medicine and Natural Products, College of Pharmacy, Jinan University Guangzhou, China.
Faculty of Health Sciences, University of Macau Macau, China.
Front Pharmacol. 2016 Mar 29;7:77. doi: 10.3389/fphar.2016.00077. eCollection 2016.
Elephantopus mollis (EM) is a traditional herbal medicine with multiple pharmacological activities. However, the efficacy of EM in treating human leukemia is currently unknown. In the current study, we report that EM23, a natural sesquiterpene lactone isolated from EM, inhibits the proliferation of human chronic myeloid leukemia (CML) K562 cells and acute myeloid leukemia (AML) HL-60 cells by inducing apoptosis. Translocation of membrane-associated phospholipid phosphatidylserines, changes in cell morphology, activation of caspases, and cleavage of PARP were concomitant with this inhibition. The involvement of the mitochondrial pathway in EM23-mediated apoptosis was suggested by observed disruptions in mitochondrial membrane potential. Mechanistic studies indicated that EM23 caused a marked increase in the level of reactive oxygen species (ROS). Pretreatment with N-acetyl-L-cysteine, a ROS scavenger, almost fully reversed EM23-mediated apoptosis. In EM23-treated cells, the expression levels of thioredoxin (Trx) and thioredoxinreductase (TrxR), two components of the Trx system involved in maintaining cellular redox homeostasis, were significantly down-regulated. Concomitantly, Trx regulated the activation of apoptosis signal-regulating kinase 1 (ASK1) and its downstream regulatory targets, the p38, JNK, and ERK MAPKs. EM23-mediated activation of ASK1/MAPKs was significantly inhibited in the presence of NAC. Furthermore, tumor necrosis factor alpha (TNF-α)-mediated activation of nuclear factor-κB (NF-κB) was suppressed by EM23, as suggested by the observed blockage of p65 nuclear translocation, phosphorylation, and reversion of IκBα degradation following EM23 treatment. Taken together, these results provide important insights into the anticancer activities of the EM component EM23 against human CML K562 cells and AML HL-60 cells.
软叶地胆草是一种具有多种药理活性的传统草药。然而，其治疗人类白血病的疗效目前尚不清楚。在本研究中，我们报告从软叶地胆草中分离出的一种天然倍半萜内酯EM23，通过诱导凋亡抑制人类慢性髓性白血病（CML）K562细胞和急性髓性白血病（AML）HL-60细胞的增殖。膜相关磷脂酰丝氨酸的易位、细胞形态的改变、半胱天冬酶的激活以及PARP的裂解与这种抑制作用相伴发生。线粒体膜电位的破坏提示线粒体途径参与了EM23介导的凋亡。机制研究表明，EM23导致活性氧（ROS）水平显著升高。用ROS清除剂N-乙酰-L-半胱氨酸预处理几乎完全逆转了EM23介导的凋亡。在EM23处理的细胞中，参与维持细胞氧化还原稳态的Trx系统的两个组分硫氧还蛋白（Trx）和硫氧还蛋白还原酶（TrxR）的表达水平显著下调。同时，Trx调节凋亡信号调节激酶1（ASK1）及其下游调节靶点p38、JNK和ERK丝裂原活化蛋白激酶（MAPK）的激活。在NAC存在下，EM23介导的ASK1/MAPK激活被显著抑制。此外，如EM23处理后观察到的p65核转位受阻、磷酸化以及IκBα降解的逆转所示，EM23抑制了肿瘤坏死因子α（TNF-α）介导的核因子κB（NF-κB）激活。综上所述，这些结果为软叶地胆草成分EM23对人类CML K562细胞和AML HL-60细胞的抗癌活性提供了重要见解。
