89780

WNT3A

PURPOSE: Posterior capsular opacification (PCO) is caused mainly by the epithelial-mesenchymal transition (EMT), proliferation, and migration of human lens epithelial (HLE) cells. wingless (Wnt) signaling has been implicated in the fibrotic process by inducing EMT and increasing the proliferation of epithelial cells. This study investigated the role of Wnt3a in PCO formation. METHODS: Wnt3a was overexpressed in the HLE B-3 cell line by transfected Wnt3a-pcDNA3 plasmid. The expressions of Wnt/beta-catenin signaling component proteins, including beta-catenin, E-cadherin, fibronectin, c-Myc, and cyclin D1, were detected by western blot analysis and immunocytofluorescence to confirm the efficiency of transfection efficiency and analyze the effects of overexpression. HLE migration ability was evaluated by transwell migration and wound healing assays, whereas HLE proliferation was analyzed by MTT [3-(4,5-dimethylthiazol-2-yl) -2,5-diphenyltetrazolium bromide] assay and flow cytometry. RESULTS: Overexpression of Wnt3a resulted in upregulated expression of beta-catenin, c-Myc, and cyclin D1. expression of the lens epithelial marker E-cadherin was down-regulated in Wnt3a-overexpressing HLE B-3 cells, whereas that of the mesenchymal marker fibronectin was upregulated. In addition, the morphology of HLE B-3 cells changed from the classic spindle shape to an irregular form. Overexpression of Wnt3a could enhance the ability of migration as determined by transwell migration and wound healing assays as well as promoted the proliferation of HLE B-3 cells by MTT assay and flow cytometry analysis. CONCLUSIONS: Wnt3a can induce EMT, migration, and proliferation of HLE cells and may be a valuable therapeutic target for the prevention and treatment of PCO.

INTRODUCTION: epithelial-mesenchymal transition (EMT) contributes to the progression and metastasis of cancer cells and is associated with a more invasive phenotype of cancer. The Wnt/beta-catenin signaling pathway is one of the major pathways involved in EMT regulation. Many studies provide evidence that beta-catenin, the key regulator of the canonical Wnt signaling pathway, is important in regulating EMT in cancer. However, the roles of Wnt3a, the representative canonical Wnt ligand, in EMT and colon cancer progression have not yet been fully explored. METHODS: The expression levels of Wnt3a and EMT-associated proteins (E-cadherin, vimentin, and beta-catenin) were assessed by immunohistochemistry in human colon cancer tissues to evaluate the clinicopathological significance of Wnt3a, as well as the correlation between Wnt3a and EMT. We then upregulated Wnt3a expression in HCT116 colon cancer cells, established a nude mouse xenograft model, detected the expression of EMT and Wnt/beta-catenin signaling-associated proteins, and observed invasion and clone-initiating abilities. RESULTS: In 203 human colon cancer tissue samples, Wnt3a protein overexpression was related to colon cancer histological differentiation (P = 0.004), clinical stage (P = 0.008), presence of metastasis and recurrence (P = 0.036), and survival time (P = 0.007) of colon cancer patients. Wnt3a expression was notably concomitant with EMT immunohistochemical features, such as reduced expression of the epithelial marker E-cadherin (P = 0.012), increased expression of the mesenchymal marker vimentin (P = 0.002), and cytoplasmic distribution of beta-catenin (P = 0.021). Results of in vitro and in vivo experiments showed that Wnt3a overexpression could alter cell morphology, regulate EMT-associated protein expression, and enhance clone-initiation and invasion. Dkk1 (antagonist of Wnt/beta-catenin signaling) could also partially reverse the expression of EMT-associated proteins in Wnt3a-overexpressing cells. CONCLUSIONS: Wnt3a expression was associated with EMT and promoted colon cancer progression. The EMT-inducing effect was partially due to the stimulative effect of Wnt3a on the Wnt/beta-catenin pathway.

Paraxial mesoderm is the tissue which gives rise to the skeletal muscles and vertebral column of the body. A gene regulatory network operating in the formation of paraxial mesoderm has been described. This network hinges on three key factors, Wnt3a, Msgn1 and Tbx6, each of which is critical for paraxial mesoderm formation, since absence of any one of these factors results in complete absence of posterior somites. In this study we determined and compared the spatial and temporal patterns of expression of Wnt3a, Msgn1 and Tbx6 at a time when paraxial mesoderm is being formed. Then, we performed a comparative characterization of mutants in Wnt3a, Msgn1 and Tbx6. To determine the epistatic relationship between these three genes, and begin to decipher the complex interplay between them, we analyzed double mutant embryos and compared their phenotypes to the single mutants. Through the analysis of molecular markers in mutants, our data support the bipotential nature of the progenitor cells for paraxial mesoderm and establish regulatory relationships between genes involved in the choice between neural and mesoderm fates.CI - Copyright (c) 2012 Elsevier Inc. All rights reserved.