Honokiol induces apoptosis through p53-independent pathway in human colorectal cell line RKO.
OBJECTIVE
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.


CONCLUSIONS
Honokiol can induce RKO cells apoptosis through activating caspase cascade by p53-indepenent pathway.
Wang
Tao
T
Cancer Institute, Second Hospital of Medicine, College of Zhejiang University, Hangzhou 310009, Zhejiang Province, China.
Chen
Fei
F
Chen
Zhe
Z
Wu
Yi-Feng
YF
Xu
Xiao-Li
XL
Zheng
Shu
S
Hu
Xun
X
D000972:Antineoplastic Agents, Phytogenic / Q000627:therapeutic use*; D017209:Apoptosis / Q000187:drug effects*; D001713:Biphenyl Compounds / Q000627:therapeutic use*; D045744:Cell Line, Tumor; D015179:Colorectal Neoplasms / Q000188:drug therapy* / Q000503:physiopathology*; D006801:Humans; D017705:Lignans; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*; D000498:Allyl Compounds; D010636:Phenols
D000972:Antineoplastic Agents, Phytogenic; D001713:Biphenyl Compounds; D017705:Lignans; D016159:Tumor Suppressor Protein p53; C005499:honokiol; D000498:Allyl Compounds; D010636:Phenols