Liver Cancer
Copyright ©2008 The WJG Press and Baishideng. All rights reserved.
World J Gastroenterol. Jul 21, 2008; 14(27): 4309-4318
Published online Jul 21, 2008. doi: 10.3748/wjg.14.4309
Essential oil of Curcuma wenyujin induces apoptosis in human hepatoma cells
Yu Xiao, Feng-Qing Yang, Shao-Ping Li, Guang Hu, Simon Ming-Yuen Lee, Yi-Tao Wang
Yu Xiao, State Drug Clinical Trial Agency, Science & Technology Department, Sichuan Provincial People’s Hospital, Sichuan Academy of Medical Science, Chengdu 610072, Sichuan Province, China
Yu Xiao, Feng-Qing Yang, Shao-Ping Li, Guang Hu, Simon Ming-Yuen Lee, Yi-Tao Wang, Institute of Chinese Medical Sciences, University of Macau, Av. Padre Tomás Pereira S.J., Taipa, Macao, China
Simon Ming-Yuen Lee, Institute of Chinese Medicine, the Chinese University of Hong Kong, Hong Kong, China
Author contributions: Xiao Y performed biological research; Yang FQ performed chemical extraction and analysis; Xiao Y and Hu G prepared manuscript; Li SP, Lee SM and Wang YT contributed guidance and manuscript revision.
Correspondence to: Dr. Simon Ming-Yuen Lee, Institute of Chinese Medical Sciences, University of Macau, Av. Padre Tomas Pereira, SJ, Taipa, Macao, China. simonlee@umac.mo
Telephone: +853-3974691
Fax: +853-28841358
Received: July 20, 2007
Revised: May 9, 2008
Accepted: May 16, 2008
Published online: July 21, 2008
Abstract

AIM: To investigate the effects of the essential oil of Curcuma wenyujin (CWO) on growth inhibition and on the induction of apoptosis in human HepG2 cancer cells.

METHODS: The cytotoxic effect of drugs on HepG2 cells was measured by 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. DNA fragmentation was visualized by agarose gel electrophoresis. Cell cycle and mitochondrial transmembrane potential (ΔΨm) were determined by flow cytometry (FCM). Cytochrome C immunostaining was evaluated by fluorescence microscopy. Caspase-3 enzymatic activity was assayed by the cleavage of Ac-DEVD-R110. Cleaved PARP and active caspase-3 protein levels were measured by FCM using BD™ CBA Human Apoptosis Kit.

RESULTS: Treatment with CWO inhibited the growth of HepG2 cells in a dose-dependent manner, and the IC50 of CWO was approximately 70 &mgr;g/mL. CWO was found to inhibit the growth of HepG2 cells by inducing a cell cycle arrest at S/G2. DNA fragmentation was evidently observed at 70 &mgr;g/mL after 72 h of treatment. During the process, cytosolic HepG2 cytochrome C staining showed a markedly stronger green fluorescence than in control cells in a dose-dependent fashion, and CWO also caused mitochondrial transmembrane depolarization. Furthermore, the results clearly demonstrated that both, activity of caspase-3 enzyme and protein levels of cleaved PARP, significantly increased in a dose-dependent manner after treatment with CWO.

CONCLUSION: CWO exhibits an antiproliferative effect in HepG2 cells by inducing apoptosis. This growth inhibition is associated with cell cycle arrest, cytochrome C translocation, caspase 3 activation, Poly-ADP-ribose polymerase (PARP) degradation, and loss of mitochondrial membrane potential. This process involves a mitochondria-caspase dependent apoptosis pathway. As apoptosis is an important anti-cancer therapeutic target, these results suggest a potential of CWO as a chemotherapeutic agent.

Keywords: Essential oil; Curcuma wenyujin; Apoptosis; HepG2; Caspase-3; Mitochondrial; Cytochrome C; Cleaved Poly-ADP-ribose polymerase