Regulation of glycogen synthase kinase‐3 by thymosin beta‐4 is associated with gastric cancer cell migration

Abstract

Thymosin beta-4 (Tb4), actin-sequestering protein, plays important roles in many cellular functions including cancer cell migrations. Glycogen synthase kinase (GSK) in Wnt signaling pathway is a key molecule to control intercellular interaction. Here, we investigated whether GSK-3 activity is regulated by Tb4 and it is associated with Tb4-mediated migration in gastric cancer cells. Various expression level of Tb4 was observed in human gastric tumor tissues. Migration in gastric cancer cells, SNU638 and SNU668, was dependent on a relative expression level of Tb4. Cell migration was higher in SNU668 with a higher expression level of Tb4 than that in SNU638 with a lower Tb4. Although the level of phosphorylated(p)-GSK-3a (inactive), b-catenin, E-cadherin and E-cadherin:b-catenin complex was relatively higher, p-GSK-3b (inactive) was lower in SNU638 compared to those in SNU668 cells. LiCl, GSK-3a/b inhibitor, reduced lung metastasis of B16F10 mouse melanoma cells and SNU668 cell migration. Small interference (si)RNA of GSK-3a increased SNU638 cell migration in accordance with the reduction of E-cadherin:b-catenin complex formation through a decrease in b-catenin and E-cadherin. Expression level of GSK-3a/b, b-catenin and E-cadherin in SNU668 and SNU638 was reversed by Tb4-siRNA and by the treatment with acetylatedserine-aspartic acid-lysine-proline (SDKP) tetrapeptide of Tb4, respectively. E-cadherin expression in SNU638 cells was decreased by b-catenin-siRNA. PD98059, MEK inhibitor, or U0126, ERK inhibitor, reduced SNU668 cell migration accompanying an increase in p-GSK-3a, b-catenin and E-cadherin. Taken together, data indicated that the expression of GSK3a, b-catenin and E-cadherin could be negatively regulated by Tb4-induced ERK phosphorylation. It suggests that Tb4 could be a novel regulator to control Wnt signaling pathways.When cancer cells are away from the original place to the secondary location, cancer cell transition happens by the course of cell migration and adhesion in which a wide variety of proteins are involved and form a complex structure accompanying the reorganization of actin cytoskeleton. Thymosin beta-4 (Tb4) proteins regulate intracellular signal transduction and cytoskeleton structure.Tb4 initially isolated from the thymus in 1981 is a small and naturally occurring 43-amino acid peptide present in all cells except erythrocytes. Tb4 is one of b-thymosins that are the most abundant member of highly conserved polar 5-kDa peptides.

TIPE1 suppresses invasion and migration through down‐regulating Wnt/β‐catenin pathway in gastric cancer

“…We found TIPE1 inhibited the expression of Wnt1, a secreted ligand that activates Wnt signalling pathways, which strongly correlates with tumorigenesis and progression [23,25]. Activation of Wnt signalling pathway can promote b-catenin, a key regulator of the Wnt pathway, nuclear translocation through increasing phosphate GSK3b [26]. Indeed our results showed the amount of phosphorylated GSK3b and active b-catenin (dephosphorylated b-catenin) was dramatically inhibited by TIPE1.…”

Thymosin beta-4 regulates activation of hepatic stellate cells via hedgehog signaling

“…Previous research reported that ILK mediated Hh signaling by regulating the localization of SMO in the cilium 30 . It also demonstrated that TB4 stabilized ILK in cardiomyocyte and colon cancer cells and that overexpression of TB4 inactivated GSK3B by hyper-phosphorylating GSK3B 31–33 .…”

Thymosin β4 induces proliferation, invasion, and epithelial-to-mesenchymal transition of oral squamous cell carcinoma

“…Recently, numerous studies have reported that Tβ4 has multiple biological activities to promote angiogenesis (Grant et al 1995(Grant et al , 1999, chemotaxis (Tokura et al 2011), and wound healing (Philp et al 2004). Apparently, human gastric cancer cells, such as SNU668, showing a higher expression level of Tβ4 have a higher migratory potential compared to SNU638 cells showing relatively low expression of Tβ4 (Ryu et al 2012). Upregulation of Tβ4 expression has also been found in melanoma cell lines isolated from metastatic tumors and in clinical metastatic melanoma tissues (Nummela et al 2006).…”