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 5

Loss of Cldn2 results in a defective mucosal healing transcriptomic response, which differs from the conserved gene expression profile between WT mice recovering from IBD and patients with IBD.

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Loss of Cldn2 results in a defective mucosal healing transcriptomic resp...
(A) Scatter graph showing differential gene expression between Cldn2KO and WT mice recovering from colitis (n = 3/group). (B and C) Most prominent KEGG pathways and GO biological processes based on gene expression upregulated in Cldn2KO mice versus WT mice during recovery from colitis (n = 3/group). (D) Heatmap depicting differential gene expression, which was primarily associated with cell cycle, apoptosis, inflammation, and immune homeostasis (Cldn2KO versus WT mice; n = 3/group). (E) Most prominent downregulated KEGG pathways in Cldn2KO mice compared with WT mice (n = 3/group). (F and G) Immunoblotting and densitometric analysis of proteins involved in inflammation, proliferation, survival, and apoptosis in mice recovering from colitis (Cldn2KO; n = 5) and WT (n = 4) mice. (H) The gene profile in Cldn2KO mice recovering from colitis differs from the conserved profile between mice and humans. (I) Significant dysregulation of GO biological processes that are associated with mucosal healing in Cldn2KO mice versus WT mice. (J and K) Immunohistochemical analysis for cleaved caspase-3 and Ki67, and proliferation index (WT/Cldn2KO: n = 4/5 mice; 3 fields in each mice Swiss role). (L) Schematics showing that loss of CLDN2 results in impaired mucosal healing. Data in G and K are presented as the mean ± SEM. *P < 0.05, ***P < 0.001, ****P < 0.0001 by 2-tailed unpaired t test. Scale bar: 100 μM.