Colorectal Cancer
Copyright ©The Author(s) 2004. Published by Baishideng Publishing Group Inc. All rights reserved.
World J Gastroenterol. Aug 1, 2004; 10(15): 2205-2208
Published online Aug 1, 2004. doi: 10.3748/wjg.v10.i15.2205
Honokiol induces apoptosis through p53-independent pathway in human colorectal cell line RKO
Tao Wang, Fei Chen, Zhe Chen, Yi-Feng Wu, Xiao-Li Xu, Shu Zheng, Xun Hu
Tao Wang, Fei Chen, Zhe Chen, Xiao-Li Xu, Shu Zheng, Xun Hu, Cancer Institute, Second Hospital of Medicine College of Zhejiang University, Hangzhou 310009, Zhejiang Province, China
Yi-Feng Wu, Life Science College of Zhejiang University, Hangzhou 310009, Zhejiang Province, China
Author contributions: All authors contributed equally to the work.
Supported by the Cheung Kong Scholars Program, National Ministry of Education of China, and Li Ka Shing Foundation, Hong Kong
Correspondence to: Professor Xun Hu, Cancer Institute Second Hospital of Medicine College of Zhejiang University, Hangzhou 310009, Zhejiang Province, China. huxun@zju.edu.cn
Telephone: +86-571-87783868 Fax: +86-571-87214404
Received: February 21, 2004
Revised: February 23, 2004
Accepted: March 12, 2004
Published online: August 1, 2004
Abstract

AIM: To investigate the signal pathway of honokiol-induced apoptosis on human colorectal carcinoma RKO cells and to evaluate whether p53 and p53-related genes were involved in honokiol-treated RKO cells.

METHODS: Cell cycle distribution and subdiploid peak were analyzed with a flow cytometer and DNA fragment with electrophoresis on agarose gels. Transcriptional level of Bax, Bcl- 2, Bid and Bcl-xl was accessed by RT-PCR. Western blotting was used to measure p53 protein expression and other factors related to apoptosis. Proliferation inhibition of two cell lines (RKO, SW480) with high expression of p53 and one cell line with p53 negative expression (LS180) was monitored by MTT assay.

RESULTS: Honokiol induced RKO cell apoptosis in a dose-dependent manner. The mRNA expression level and protein level of Bid were up -regulated while that of Bcl-xl was down-regulated, but no changes in Bax and Bcl-2 were observed. Western blotting showed p53 expression had no remarkable changes in honokiol-induced RKO cell apoptosis. LS180 cells treated with honokiol exhibited apparent growth inhibition like RKO cells and Sw480 cells.

CONCLUSION: Honokiol can induce RKO cells apoptosis through activating caspase cascade by p53-indepenent pathway.

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