Yun Ji Ho, Park Young Gyun, Lee Kyung-Mi, Kim Jungho, Nho Chu Won
Natural Products Research Center, KIST Gangneung Institute, Gangneung, Gangwon-do, Korea.
Department of Life Science, Sogang University, Seoul, Korea.
Mol Nutr Food Res. 2015 Jun;59(6):1053-62. doi: 10.1002/mnfr.201400739. Epub 2015 Apr 29.
Octamer-binding transcription factor 4 (Oct4) is a key regulator of pluripotent embryonic stem cell maintenance. However, increasing evidence has suggested that Oct4 is also expressed in cancer stem cells (CSCs) and is associated with tumor progression and chemoresistance. Curcumin (CUR) is a widely used cancer chemopreventive agent, and it has been used to treat several diseases including cancers. Here, we investigated whether CUR-induced apoptotic cell death by inhibiting Oct4 levels and examining molecular mechanisms in NCCIT human embryonic carcinoma cells.
CUR significantly inhibited Oct4 transcription levels in a dose-dependent manner by dual luciferase experiment, also decreased mRNA and protein levels in NCCIT human embryonic carcinoma cells, which express high levels of endogenous Oct4. Interestingly, we found that CUR treatment increased apoptotic cell death including subG0/G1 contents, cleavage caspases, and pro-apoptotic protein, as confirmed with a series of loss-of-function experiments using Oct4 siRNA. Furthermore, CUR induced marked total level of glycogen synthase kinase 3 beta (GSK-3β), resulting in an increase in apoptotic cell death, was evaluated using chemical inhibitor of GSK3-3β.
These data suggest that CUR induces apoptotic cell death through Oct4 inhibition and GSK-3β activation. Thus, CUR may be a useful cancer chemopreventive agent to suppress tumor progression or to improve chemoresistance by eliminating CSCs.
八聚体结合转录因子4（Oct4）是多能胚胎干细胞维持的关键调节因子。然而，越来越多的证据表明，Oct4也在癌症干细胞（CSCs）中表达，并与肿瘤进展和化疗耐药性相关。姜黄素（CUR）是一种广泛使用的癌症化学预防剂，已被用于治疗包括癌症在内的多种疾病。在此，我们研究了CUR是否通过抑制Oct4水平并检测NCCIT人胚胎癌细胞中的分子机制来诱导凋亡性细胞死亡。
通过双荧光素酶实验，CUR以剂量依赖性方式显著抑制Oct4转录水平，同时也降低了NCCIT人胚胎癌细胞中的mRNA和蛋白质水平，这些细胞内源性Oct4表达水平较高。有趣的是，我们发现CUR处理增加了凋亡性细胞死亡，包括亚G0/G1期细胞含量、半胱天冬酶裂解以及促凋亡蛋白，这通过使用Oct4 siRNA进行的一系列功能丧失实验得以证实。此外，使用GSK3 - 3β化学抑制剂评估发现，CUR诱导糖原合酶激酶3β（GSK - 3β）总水平显著升高，导致凋亡性细胞死亡增加。
这些数据表明，CUR通过抑制Oct4和激活GSK - 3β诱导凋亡性细胞死亡。因此，CUR可能是一种有用的癌症化学预防剂，可通过消除CSCs来抑制肿瘤进展或改善化疗耐药性。
