Hu et al. Journal of Experimental & Clinical Cancer Research 2010, 29:154 http://www.jeccr.com/content/29/1/154 R E S E A R C H Open Access Glycogen synthase kinase-3b inhibition induces nuclear factor- B-mediated apoptosis in pediatric acute lymphocyte leukemia cells Yanni Hu1, Xiaoyan Gu1, Ruiyan Li1, Qing Luo1, Youhua Xu1,2* Abstract Background: Molecular therapies that target genetic abnormalities in leukemic cells and their affected signaling pathways have been emerging in pediatric acute lymphoblastic leukemia (ALL). Glycogen synthase kinase-3b (GSK- 3b) has recently been found to positively regulate the activity of nuclear factor- B (NF- B). Here, we investigated the relationship between GSK-3b inhibition and NF- B in apoptosis of pediatric primary leukemia cells obtained from 39 newly diagnosed ALL children in China. Methods: Bone marrow mononuclear cells (BMMC) were isolated by density gradient centrifugation from the heparinized aspirates of children with ALL. We used immunofluorescence staining to detect nuclear GSK-3b in these cells. After treatment with chemically distinct GSK-3b inhibitors in vitro, NF- B transcriptional activity was identified by means of western blotting and electrophoretic mobility shift assay (EMSA). NF- B-mediated apoptosis was detected by Annexin V-PE/7-AAD double-staining flow cytometry. The expression level of the survivin gene was detected by reverse-transcriptase polymerase chain reaction (RT-PCR). Results: GSK-3b significantly accumulates in the nuclei of ALL cells than in the nuclei of control cells. Cell death induced by GSK-3b inhibition in ALL cells was mediated by a downregulation of NF- B p65 transcriptional activity. GSK-3b inhibition significantly decreased the expression of the NF- B target gene survivin. Conclusions: These results indicate that inhibition of GSK-3b downregulates the NF- B activation pathway, leading to suppression of the expression of an NF- B-regulated gene and promotion of apoptosis in ALL cells in vitro. Furthermore, our findings suggest that GSK-3b or NF- B is a potential therapeutic target in the treatment of pediatric ALL. Introduction Acute lymphocytic leukemia (ALL) is the most common malignancy diagnosed in children, and it accounts for approximately one-third of all pediatric cancers. Although contemporary treatments cure more than 80% of children with ALL, some patients require intensive treatment and many patients still develop serious acute and late complications because of the side effects of the treatments [1]. Therefore, new treatment strategies are needed to improve not only the cure rate but also the quality of life of these children [2]. * Correspondence: xuyouhua0504@sina.com 1Laboratory of Oncology, Affiliated Children’s Hospital, Chongqing Medical University, No.136, Zhongshan 2nd Road, Yuzhong District, Chongqing 86 400014, China Full list of author information is available at the end of the article Glycogen synthase kinase-3 (GSK-3) is a serine/ threonine protein kinase, whose activity is inhibited by a variety of extracellular stimuli including insulin, growth factors, cell specification factors, and cell adhesion [3-5]. Two homologous mammalian GSK-3 isoforms are encoded by different genes, GSK-3a and GSK-3b. Recently, GSK-3 has been recognized as a key compo- nent of a diverse range of cellular functions essential for survival [6]. Fibroblasts from GSK-3b-deficient embryos were sensitized to apoptosis and showed reduced nuclear factor- B (NF- B) function [7]. Furthermore, it has been shown that GSK-3b is a prosurvival factor in pancreatic tumor cells, partly through its ability to regu- late the NF- B pathway [8]. These findings suggest a role for GSK-3b (but not GSK-3a) in the regulation of NF- B activation. Recent experimental evidence has © 2010 Hu et al; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.