Claudin-2 protects against colitis-associated cancer by promoting colitis-associated mucosal healing
Rizwan Ahmad, Balawant Kumar, Ishwor Thapa, Raju Lama Tamang, Santosh K. Yadav, Mary K. Washington, Geoffrey A. Talmon, Alan S. Yu, Dhundy K. Bastola, Punita Dhawan, Amar B. Singh
Rizwan Ahmad, Balawant Kumar, Ishwor Thapa, Raju Lama Tamang, Santosh K. Yadav, Mary K. Washington, Geoffrey A. Talmon, Alan S. Yu, Dhundy K. Bastola, Punita Dhawan, Amar B. Singh
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Research Article Gastroenterology

Claudin-2 protects against colitis-associated cancer by promoting colitis-associated mucosal healing

Abstract

Patients with inflammatory bowel disease (IBD) are susceptible to colitis-associated cancer (CAC). Chronic inflammation promotes the risk for CAC. In contrast, mucosal healing predicts improved prognosis in IBD and reduced risk of CAC. However, the molecular integration among colitis, mucosal healing, and CAC remains poorly understood. Claudin-2 (CLDN2) expression is upregulated in IBD; however, its role in CAC is not known. The current study was undertaken to examine the role for CLDN2 in CAC. The AOM/DSS-induced CAC model was used with WT and CLDN2-modified mice. High-throughput expression analyses, murine models of colitis/recovery, chronic colitis, ex vivo crypt culture, and pharmacological manipulations were employed in order to increase our mechanistic understanding. The Cldn2KO mice showed significant inhibition of CAC despite severe colitis compared with WT littermates. Cldn2 loss also resulted in impaired recovery from colitis and increased injury when mice were subjected to intestinal injury by other methods. Mechanistic studies demonstrated a possibly novel role of CLDN2 in promotion of mucosal healing downstream of EGFR signaling and by regulation of Survivin expression. An upregulated CLDN2 expression protected from CAC and associated positively with crypt regeneration and Survivin expression in patients with IBD. We demonstrate a potentially novel role of CLDN2 in promotion of mucosal healing in patients with IBD and thus regulation of vulnerability to colitis severity and CAC, which can be exploited for improved clinical management.

Authors

Rizwan Ahmad, Balawant Kumar, Ishwor Thapa, Raju Lama Tamang, Santosh K. Yadav, Mary K. Washington, Geoffrey A. Talmon, Alan S. Yu, Dhundy K. Bastola, Punita Dhawan, Amar B. Singh

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Figure 3

Colitis-mediated regulation of CLDN2 expression is context dependent and biphasic.

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Colitis-mediated regulation of CLDN2 expression is context dependent and...
(A and B) Epithelial enriched fractions of WT mouse colon that were untreated, subjected to DSS-induced colitis and recovery, or chronic DSS-induced colitis (n = 3/group). (C and D) Representative images and IHC intensity analysis using anti-CLDN2 antibody (n = 5/group). (E) Coimmunofluorescence image analysis for CLDN2 and SCA-1 in colon Swiss roll of mice subjected to acute DSS-induced colitis, DSS-induced colitis/recovery, or chronic DSS-induced colitis (n = 5/group). (F and G) Coimmunofluorescence and quantitative analysis using anti-CLDN2 and -Ki67 antibodies (n = 6/group). (H and I) MTT assay and RT-qPCR analysis using Caco2 cells subjected to DSS-induced injury and subsequent recovery (n = 3 independent experiments). (J) Immunoblot analysis for CLDN2, ECAD, c-Myc, and P27/Kip1 (n = 3 independent experiments). (K) Model depicting regulation of CLDN2 during colitis (injury phase) and recovery (repair/regeneration phase). Data in B, D, G, and H–J are presented as the mean ± SEM. *P < 0.05, **P < 0.01, ***P < 0.001, ****P < 0.0001, $$$$P < 0.0001 by 1-way ANOVA with Tukey’s test. Scale bar: 100 μM (C, E, and F); 200 μM (C).