Claudin-1 regulates cellular transformation and metastatic behavior in colon cancer
Punita Dhawan, … , M. Kay Washington, R. Daniel Beauchamp
Punita Dhawan, … , M. Kay Washington, R. Daniel Beauchamp
Published July 1, 2005
Citation Information: J Clin Invest. 2005;115(7):1765-1776. https://doi.org/10.1172/JCI24543.
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Claudin-1 regulates cellular transformation and metastatic behavior in colon cancer

Abstract

Disruption of the cell-cell junction with concomitant changes in the expression of junctional proteins is a hallmark of cancer cell invasion and metastasis. The role of adherent junction proteins has been studied extensively in cancer, but the roles of tight junction (TJ) proteins are less well understood. Claudins are recently identified members of the tetraspanin family of proteins, which are integral to the structure and function of TJs. Recent studies show changes in expression/cellular localization of claudins during tumorigenesis; however, a causal relationship between claudin expression/localization and cancer has not been established. Here, we report an increased expression of claudin-1 in human primary colon carcinoma and metastasis and in cell lines derived from primary and metastatic tumors. We also report frequent nuclear localization of claudin-1 in these samples. Genetic manipulations of claudin-1 expression in colon cancer cell lines induced changes in cellular phenotype, with structural and functional changes in markers of epithelial-mesenchymal transition. Furthermore, we demonstrate that changes in claudin-1 expression have significant effects on growth of xenografted tumors and metastasis in athymic mice. We further provide data suggesting that the regulation of E-cadherin expression and β-catenin/Tcf signaling is a possible mechanism underlying claudin-1–dependent changes.

Authors

Punita Dhawan, Amar B. Singh, Natasha G. Deane, YiRan No, Sheng-Ru Shiou, Carl Schmidt, John Neff, M. Kay Washington, R. Daniel Beauchamp

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Figure 3

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Effects of siRNA-based inhibition of claudin-1 expression in the metasta...
Effects of siRNA-based inhibition of claudin-1 expression in the metastatic SW620 cells. (A) Western blot analysis of SW620 cells stably expressing claudin-1 siRNA (SW620siRNA). Equal amounts of total protein were subjected to immunoblot analysis using anti–claudin-1 antibody. The clones shown were selected based on similar levels of inhibition of claudin-1 expressions. The same lysates were also subjected to immunoblot analysis for claudin-4 to determine the specificity of the siRNA oligonucleotide. Immunoblotting for vimentin, FSP1, and E-cadherin was performed using the same lysates. (B) The upper panel represents immunofluorescence localization of claudin-1, β-catenin, E-cadherin, and vimentin in SW620siRNA cells. Only SW620control cells are shown, as there were no visible differences between SW620control cells and parental SW620 cells. The lower panel represents results of immunoblot analysis using cytosolic and membrane-specific fractions for expressions of β-catenin and E-cadherin in SW620control and SW620siRNA cells. (C) Representative phase-contrast images of monolayer cultures of SW620control, and SW620siRNA cells. (D) Representative photomicrographs of cell migration by monolayer wound-healing assay using SW620control and SW620siRNA clones. Photomicrographs were obtained 0, 24, 48, and 72 hours after standard scrape wounding, as described in Methods.