Abstract
Abstract Disruption of cell-cell junctions and changes in the expression of junctional proteins is a critical event in the progression of cancer. We have previously reported a tumor stage specific increase in the expression of a tight junction protein, Claudin-1, in colorectal cancer and its association with tumor-growth and metastasis. Furthermore, our studies have shown that in colon cancer cells, claudin-1 expression is regulated by a complex interaction between APC, Smad4 and β-catenin, three important regulators of colorectal carcinogenesis. We wanted to investigate the consequence of overexpression of claudin -1 in vivo specifically in the colon. We have generated a transgenic mouse model in which Claudin-1 is expressed under the control of the villin promoter. The villin promoter is expressed in the adult intestinal epithelium and has been frequently used for intestinal-specific overexpression of several genes of interest. Western blot analysis demonstrated a robust expression of claudin-1 in the colon, small intestine and cecum of transgenic mice while low levels of expression were present in wild type mice. These results are confirmed with immunohistochemistry analysis where claudin-1 was largely expressed on the membrane in the same tissues. Colonic permeability was assayed using FITC-dextran, however, there was no significant difference between the flux of FITC-dextran in wild-type and transgenic mice. Real-Time PCR analysis for inflammatory cytokine expression showed a decrease in IL-10 mRNA in transgenic mice compared to that of wild-type mice. Further, treatment with Dextran Sodium Sulfate (DSS) to induce colitis showed a significant decrease in body weight of claudin-1 transgenic mice as compared to wild type mice on DSS. An increase in disease severity was observed in transgenic mice as determined by histology scoring, as well as a significant difference in the ratio of colon weight to colon length. Claudin-1 expression in transgenic mice is localized to the membrane, where it maintains its normal function. Further experiments with this model include combined treatment with DSS and AOM to examine the effect of Claudin -1 overexpression in inflammation-induced-tumorigenesis as well as performing crosses with sporadic models of tumorigenesis involving mutations in the APC gene, to examine the role of claudin-1 upregulation in tumor formation and progression. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4331. doi:10.1158/1538-7445.AM2011-4331
Published Version
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