Esophageal Cancer
Copyright ©2008 The WJG Press and Baishideng. All rights reserved.
World J Gastroenterol. Jul 7, 2008; 14(25): 3982-3989
Published online Jul 7, 2008. doi: 10.3748/wjg.14.3982
Lithium inhibits proliferation of human esophageal cancer cell line Eca-109 by inducing a G2/M cell cycle arrest
Jin-Sheng Wang, Cui-Lian Wang, Ji-Fang Wen, Yong-Jin Wang, Yong-Bin Hu, Hong-Zheng Ren
Jin-Sheng Wang, Ji-Fang Wen, Yong-Bin Hu, Hong-Zheng Ren, Department of Pathology, Xiangya Medical College, Central South University, Changsha 410008, Hunan Province, China
Jin-Sheng Wang, Cui-Lian Wang, Yong-Jin Wang, Department of Pathology, Changzhi Medical College, Changzhi 046000, Shanxi Province, China
Author contributions: Wang JS and Wang CL contributed equally to this work; Wang JS designed the research and wrote the manuscript; Wang CL analyzed the data by Western blotting and RT-PCR; Wen JF corrected the manuscript; Wang YJ dealt with the statistical data; Hu YB analyzed the results of cytobiology and immunofluorescence; and Ren HZ did cell culture.
Correspondence to: Ji-Fang Wen, Professor, Department of Pathology, Xiangya Medical College, Central South University, Changsha 410008, Hunan Province, China. jifangwen@hotmail.com
Telephone: +86-731-2650400
Fax: +86-731-2650400
Received: February 23, 2008
Revised: May 10, 2008
Accepted: May 17, 2008
Published online: July 7, 2008
Abstract

AIM: To investigate the effect of lithium on proliferation of esophageal cancer (EC) cells and its preliminary mechanisms.

METHODS: Eca-109 cells were treated with lithium chloride, a highly selective inhibitor of glycogen synthase kinase 3β (GSK-3β), at different concen-trations (2-30 mmol/L) and time points (0, 2, 4, 6 and 24 h). Cell proliferative ability was evaluated by 3-(4,5-dimethylthiazole-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay, and cell cycle distribution was examined by flow cytometry. Expressions of p-GSK-3β, β-catenin, cyclin B1, cdc2 and cyclin D1 protein were detected by Western blotting, and the subcellular localization of β-catenin was determined by immunofluorescence. The mRNA level of cyclin B1 was detected by reverse transcription polymerase chain reaction (RT-PCR).

RESULTS: Lithium could inhibit the proliferation of Eca-109 cells. Lithium at a concentration of 20 mmol/L lithium for 24 h produced obvious changes in the distribution of cell cycle, and increased the number of cells in G2/M phase (P < 0.05 vs control group). Western blotting showed that lithium inhibited GSK-3β by Ser-9 phosphorylation and stabilized free β-catenin in the cytoplasm. Immunofluorescence further confirmed that free β-catenin actively translocated to the nucleus. Moreover, lithium slightly elevated cyclin D1 protein expression, whereas lowered the cyclin B1 expression after 24 h lithium exposure and no obvious change was observed for cdc2 protein.

CONCLUSION: Lithium can inhibit the proliferation of human esophageal cancer cell line Eca-109 by inducing a G2/M cell cycle arrest, which is mainly mediated through the inhibition of lithium-sensitive molecule, GSK-3β, and reduction of cyclin B1 expression.

Keywords: Lithium; Esophageal cancer; Cell cycle; Glycogen synthase kinase 3β