Moon Dong-oh, Kim Moon-ok, Lee Jae-dong, Choi Yung-hyun, Lee Min-ki, Kim Gi-young
Faculty of Applied Marine Science, Cheju National University, Jeju Special Self-Governing Province, Republic of Korea.
Acta Pharmacol Sin. 2007 Aug;28(8):1205-14. doi: 10.1111/j.1745-7254.2007.00615.x.
To investigate the molecular mechanisms of ZD1839-induced apoptosis in human leukemic U937 cells.
The inhibition of human leukemic U937 cell growth was assessed by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphnyl-2H-tetrazolim bromide (MTT) assays, lactate dehydrogenase (LDH) release, and cell cycle distribution. The expression of anti- and pro-apoptotic proteins was detected by Western blot analysis.
This study demonstrated that ZD1839 induced apoptosis in leukemic U937 cells by the downregulation of Bcl-2, caspase activation and subsequent apoptotic features. Cotreatment with ZD1839 and the caspase-3 inhibitor z-DEVD-fmk blocked apoptosis, indicating that caspase-3 activation is at least partially responsible for ZD1839-induced apoptosis. The ectopic expression of Bcl-2 attenuated caspase-3 activation, PARP cleavage, and subsequent indicators of apoptosis, including sub-G1 DNA content and LDH release. These results indicate that the downregulation of Bcl-2 plays a major role in the initiation of ZD1839-induced apoptosis, and that the activation of a caspase cascade is involved in the execution of apoptosis. Furthermore, ZD1839 treatment triggered the activation of p38 mitogen-activated protein kinase (MAPK) and the down-regulation of c-Jun-N-terminal kinase (JNK), extracellular signal-regulated kinase (ERK) and phosphatidyl inositol 3-kinase (PI3K)/Akt. The inhibition of the ERK and PI3K/Akt pathways also significantly increased cellular death.
ZD1839 activated caspase-3 and the inhibited Bcl-2 in human leukemic U937 cells through the downregulation of the ERK and PI3K/Akt pathways.
研究ZD1839诱导人白血病U937细胞凋亡的分子机制。
通过3-(4,5-二甲基-2-噻唑基)-2,5-二苯基-2H-四氮唑溴盐（MTT）法、乳酸脱氢酶（LDH）释放及细胞周期分布评估人白血病U937细胞生长的抑制情况。采用蛋白质免疫印迹分析检测抗凋亡和促凋亡蛋白的表达。
本研究表明，ZD1839通过下调Bcl-2、激活半胱天冬酶及随后出现的凋亡特征诱导白血病U937细胞凋亡。ZD1839与半胱天冬酶-3抑制剂z-DEVD-fmk联合处理可阻断凋亡，表明半胱天冬酶-3激活至少部分参与了ZD1839诱导的凋亡。Bcl-2的异位表达减弱了半胱天冬酶-3激活、聚ADP核糖聚合酶（PARP）裂解以及随后的凋亡指标，包括亚G1期DNA含量和LDH释放。这些结果表明，Bcl-2的下调在ZD1839诱导凋亡的起始过程中起主要作用，并且半胱天冬酶级联反应的激活参与了凋亡的执行。此外，ZD1839处理引发了p38丝裂原活化蛋白激酶（MAPK）的激活以及c-Jun氨基末端激酶（JNK）、细胞外信号调节激酶（ERK）和磷脂酰肌醇3激酶（PI3K）/蛋白激酶B（Akt）的下调。ERK和PI3K/Akt信号通路的抑制也显著增加了细胞死亡。
ZD1839通过下调ERK和PI3K/Akt信号通路激活人白血病U937细胞中的半胱天冬酶-3并抑制Bcl-2。
