4488

MSX2

In our study, we found that bone morphogenetic protein 4 (BMP4) has a novel effect as an inducer of epithelial-mesenchymal transition (EMT) on Panc-1 cells, a human pancreatic carcinoma cell line. BMP4-treated Panc-1 cells showed loose cell contacts and a scattered, fibroblast-like appearance along with E-cadherin downregulation, Vimentin upregulation and enhanced cell migration, which are characteristic of EMT. BMP4 treatment also induced homeobox gene MSX2 expression, which we previously showed to be associated with EMT in pancreatic carcinoma cells. BMP4 treatment activated the Smad signaling pathway, and extracellular signal-related kinase (ERK) and p38 mitogen-activated kinase (MAPK) pathways in these cells. MSX2 was markedly induced by BMP4 through the ERK and p38 MAPK pathways in collaboration with the Smad signaling pathway. The repression of E-cadherin, induction of Vimentin and enhanced cell migration disappeared when siRNA-based MSX2 downregulated pancreatic cancer cells were treated with BMP4. These findings indicate that BMP4 may be involved in pancreatic carcinoma development through the promotion of EMT and that MSX2 is indispensable to this process.CI - 2007 Wiley-Liss, Inc.

MSX2 is thought to be a regulator of organ development and a downstream target of the ras signaling pathway; however, little is known about the role of MSX2 in the development of pancreatic cancers, most of which harbor a K-ras gene mutation. Therefore, we examined whether the presence of MSX2 correlates with the malignant behavior of pancreatic cancer cells. BxPC3 pancreatic cancer cells that stably overexpress MSX2 showed a flattened and scattered morphology accompanied by a change in localization of E-cadherin and beta-catenin from membrane to cytoplasm. Cell proliferation rate, cell migration, and anchorage-independent cell growth were enhanced in MSX2-expressing cells. Injection of MSX2-expressing cells into the pancreas of nude mice resulted in a significant increase in liver metastases and peritoneal disseminations compared with injection of control cells. Microarray analysis revealed a significant induction of Twist 1 expression in cells that express MSX2. When MSX2 was inactivated in pancreatic cancer cells following transfection with an MSX2-specific small interfering RNA, Twist 1 was down-regulated. Immunohistochemistry of human pancreatic carcinoma tissue revealed that MSX2 was frequently expressed in cancer cells, and that increased expression of MSX2 significantly correlated with higher tumor grade, vascular invasion, and Twist 1 expression. These data indicate that MSX2 plays a crucial role in pancreatic cancer development by inducing changes consistent with epithelial to mesenchymal transition through enhanced expression of Twist 1.

Bone morphogenetic proteins (BMPs) initiate differentiation in human embryonic stem cells (hESCs) but the exact mechanisms have not been fully elucidated. We demonstrate here that SLUG and MSX2, transcription factors involved in epithelial-mesenchymal transitions, essential features of gastrulation in development and tumor progression, are important mediators of BMP4-induced differentiation in hESCs. Phosphorylated Smad1/5/8 colocalized with the SLUG protein at the edges of hESC colonies where differentiation takes place. The upregulation of the BMP target SLUG was direct as shown by the binding of phosphorylated Smad1/5/8 to its promoter, which interrupted the formation of adhesion proteins, resulting in migration. Knockdown of SLUG by short hairpin RNA blocked these changes, confirming an important role for SLUG in BMP-mediated mesodermal differentiation. Furthermore, BMP4-induced MSX2 expression leads to mesoderm formation and then preferential differentiation toward the cardiovascular lineage.CI - (c) 2013 AlphaMed Press.

epithelial-mesenchymal transition (EMT) is a process occurring during both embryogenesis and early stages of invasive cancer. epithelial cells that undergo EMT become more migratory and invasive with a mesenchymal morphology. Herein we assess EMT induction in a mouse mammary epithelial cell line driven by Msx2, a homeobox-containing transcription factor important during mammary gland development. NMuMG cells, a normal mouse mammary epithelial cell line, stably transfected with a Msx2 cDNA showed downregulation of an epithelial marker E-cadherin and upregulation of the mesenchymal markers vimentin and N-cadherin. Furthermore, overexpression of Cripto-1, a member of the epidermal growth factor-CFC protein family already known to be involved in EMT, was detected in Msx2-transfected cells. The expression of Cripto-1 was accompanied by activation of the tyrosine kinase c-Src pathway and an increase in the invasive ability of the cells. Functional assays also demonstrated inhibition of the invasive behavior of the Msx2-transfected cells by a c-Src specific inhibitor. Moreover, immunohistochemistry of human infiltrating breast carcinomas showed positive staining for Msx2 only in the infiltrating tumor cells while the non-infiltrating tumor cells were negative. These results suggest that Msx2 may play a significant role in promoting EMT in epithelial cells that acquire properties involved in tumor invasion. J. Cell. Physiol. 219: 659-666, 2009. Published 2009 Wiley-Liss, Inc.