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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Effects of siRNA-based inhibition of claudin-1 expression in SW620 cells...
Effects of siRNA-based inhibition of claudin-1 expression in SW620 cells on proliferation, anchorage-independent growth, and invasion. (A) Results of soft agar assay. Experiments were performed as described in Methods. The number of soft agar colonies presented is the mean of colony counts from 3 different experiments. (B) A cell invasion assay was performed using 24-well transwells coated with collagen type I (100 μg/ml). After 72 hours of plating, cells from the top of the filter were removed, and the cells that invaded the coated membrane were fixed and counted. Data are presented as mean colony counts in ten ×20 microscopic fields from duplicate wells. *P < 0.05, as compared to control. (C) Gelatin zymography to determine the activities of MMP-2 and MMP-9 in SW620control cells and in all 3 SW620siRNA clones was performed as described in the Methods. (D) Cellular proliferation was measured in SW620control and SW620siRNA cells using MTT assay at 1, 3, 5, and 7 days after plating equal number of cells. (E) The anoikis assay was performed by plating the SW620control and SW620siRNA cells on polyHEMA-coated culture dishes for 72 hours as described in Methods. Values for control cells were considered 100%, and any differences are expressed relative to that value. Each bar represents the mean ± SD of 3 experiments. (F) The anoikis-induced apoptosis was quantitated using apoptosis-specific ELISA. Values for control cells were considered 100%, and any changes were compared with that value. Each bar represents the mean ± SD of 3 experiments.