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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Research Article Oncology

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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Effect of inhibition of claudin-1 on E-cadherin expression and β-catenin...
Effect of inhibition of claudin-1 on E-cadherin expression and β-catenin/Tcf/Lef activity. (A) Endogenous levels of E-cadherin mRNA were measured by semiquantitative RT-PCR using total RNA from SW620 parental or SW620control cells or 3 individual clones of SW620siRNA cells as described in Methods. Primers for actin were used as internal control in the same reaction. -ve control, without reverse transcriptase. (B) The luciferase reporter activity under the control of human E-cadherin promoter construct was measured in the SW620control and SW620siRNA cells. Each bar represents the mean ± SD of 3 experiments. (C) The endogenous levels of Snail and Slug mRNA measured by semiquantitative RT-PCR using RNA from SW620 parental, SW620control, and SW620siRNA cells. Primers for actin were used as a control. (D) SW480control and SW480claudin-1 or SW620control and SW620siRNA cells were transiently cotransfected with TOPflash or FOPflash reporter constructs and SV40–β-galactosidase as internal control (upper panel). Tcf-mediated gene transcription was determined by the ratio of pTOPflash to pFOPflash luciferase activity. Transfections were done in triplicate, and each bar represents the mean ± SD of 3 experiments. Immunoblot analysis of c-Myc in SW480claudin-1 and SW620siRNA cells compared with their respective control cells (lower panel).