Mishra et al. Journal of Molecular Signaling 2010, 5:9 http://www.jmolecularsignaling.com/content/5/1/9 Open Access RESEARCH ARTICLE © 2010 Mishra 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. Research article Glycogen Synthase Kinase-3beta regulates Snail and beta-catenin during gastrin-induced migration of gastric cancer cells Prajna Mishra 1 , Subramanian Senthivinayagam 1 , Ajay Rana 2,3 and Basabi Rana* 1,2,3 Abstract Background: The gastrointestinal peptide hormone gastrin is known to regulate various cellular processes including proliferation, migration and metastasis in gastrointestinal (GI) cells. The studies described here were undertaken to elucidate in detail the signaling pathways mediating the migratory responses of amidated gastrin (G17) and to understand the involvement of the serine/threonine kinase Glycogen Synthase Kinase-3 beta (GSK3β) in this. Results: Our results indicate that incubation of gastric cancer cells overexpressing CCK2 receptor (AGSE cells) with G17 results in a dose and time dependent increase of GSK3β Ser9 phosphorylation, indicative of an inhibition of the kinase. Pretreatment with a pharmacological inhibitor of PI3Kinase pathway (Wortmannin) was unable to antagonize G17- induced GSK3β Ser9 phosphorylation, suggesting that this might involve PI3Kinase-independent pathways. Treatment with G17 was also associated with increased Snail expression, and β-catenin nuclear translocation, both of which are GSK3β downstream targets. Pretreatment with a pharmacological inhibitor of GSK3β (AR-A014418) augmented Snail expression and β-catenin nuclear translocation in the absence of G17, whereas overexpression of a phosphorylation deficient mutant of GSK3β (S9A) abrogated Snail promoter induction. These suggested that G17 modulates Snail and β-catenin pathways via inhibiting GSK3β. In addition, overexpression of GSK3β wild type (WT ) or S9A mutant inhibited G17-induced migration and MMP7 promoter induction. G17 studies designed following small interference RNA (siRNA)-mediated knockdown of Snail and β-catenin expression indicated a significant reduction of G-17-induced migration and MMP7 promoter induction following combined knockdown of both proteins. Conclusion: Our studies indicate that inhibition of GSK3β is necessary to activate G17-induced migratory pathways in gastric cancer cells. Inhibition of GSK3β leads to an induction of Snail expression and β-catenin nuclear translocation, both of which participate to promote G17-induced migration. Background Gastric cancer is the second leading cause of cancer- related deaths worldwide [1], and are often characterized as highly aggressive and unresponsive to therapy [2]. The major risk factor contributing to this disease include Heli- cobacter pylori (H. pylori) infection, diet as well as genetic background [3,4]. Interestingly, studies during the past two decades have also demonstrated that the gastrointes- tinal (GI) peptide hormone gastrin might contribute towards the pathobiology of gastric cancers. In addition to regulating gastric acid secretion, mature gastrin (G-17) and its unprocessed intermediate forms progastrin and glycine extended gastrin (Gly-G) can regulate growth in a variety of cancer cells [5,6]. Results from transgenic mice show that mice overexpressing the amidated form of gas- trin have increased proliferation of gastric mucosa [7], which can synergize with Helicobacter infection leading to the development of invasive gastric cancer [8]. Pro- longed hypergastrinemia increases the relative risk of developing colon cancer [9] and might promote adenoma to carcinoma progression [10]. Recent studies have con- firmed gastrin to be an essential cofactor for carcinogene- sis of gastric corpus [11]. In addition, significantly high levels of plasma gastrin has been reported in patients with gastric cancer, with high expression of gastrin and * Correspondence: brana@lumc.edu 1 Department of Medicine, Division of Gastroenterology, Hepatology and Nutrition, Loyola University Chicago, 2160 South First Avenue, Maywood, IL 60153, USA Full list of author information is available at the end of the article