Colorectal cancer (CRC) is one of the leading causes of cancer-related deaths in the Veterans armed forces personnel and each year Veterans affairs manages and treats ~175,000 colorectal cancer patients [1]. Although, significant advances are made in the screening/diagnosis of the disease, treatment options remain only moderately successful and primarily include surgical resection and chemotherapy. Importantly, disease progression and metastasis remain the prime cause of the morbidity and mortality among VA-CRC patients. Thus, new therapies with the promise to inhibit CRC progression are urgently needed. Our studies are an important step in that direction. Notably, extensive work from our and other laboratories has confirmed that expression of claudin-1 is highly upregulated in CRC in a stage-specific manner, and is causally associated with CRC growth and progression. Now, using a novel mouse model of intestine-specific claudin-1 overexpression, we show novel role of claudin-1 in the regulation of Notch-signaling and colonocyte maturation/goblet cell differentiation/Muc-2 expression. We further demonstrate multi-fold increase in colonic tumor burden (tumor incidence and growth) and aggressiveness in the offspring generated through the cross between APCmin and claudin-1 transgenic mice. In our continued study, we have now generated evidence that Notch- and Wnt-signaling synergize in claudin-1-dependent manner to augment CRC in APCmin/Cl-1 mice, possibly through the regulation of cancer stem cells. Taken together, our hypothesis is that increased claudin-1 expression induces Notch-hyper activation to dysregulate normal colonic differentiation and homeostasis, and thus induces susceptibility to CRC growth &progression through the synergy between Notch and Wnt- signaling. To test our hypothesis, we propose following specific aims:
Specific Aim 1. Determine that claudin-1 expression modulates Notch-signaling to regulate colon tumorigenesis. Here we will: a) determine that Notch-signaling regulates increased tumorigenesis in APCmin/Cl-1 mice;b) determine whether mucosal inflammation contributes to Claudin-1-dependent increase in colon tumorigenesis and/or aggressiveness;c) determine the mechanism/s underlying Claudin-1-dependent regulation of Notch-activation.
Specific Aim 2. To determine that Notch synergizes with Wnt/b-catenin signaling to regulate claudin-1- dependent increase in colon tumorigenesis. Here, we will determine: a) the impact of inhibition of Wnt/b- catenin-signaling on colon tumorigenesis in APCmin/Cl-1 mice.;b) that claudin-1-dependent increase in Wnt/b- catenin signaling depends upon Notch-activation and to examine the underlying mechanism/s;c) whether claudin-1 expression correlates with Notch and b-catenin/Wnt-activation in colon cancer patients and its potential association with the aggressiveness of cancer.
Specific Aim 3. To investigate the role of APC/ Wnt-signaling in the regulation of colonic Claudin-1 expression. Here, we will: a) examine the role of APC (WT)-Smad4 axis in the regulation of Claudin-1 expression;b) determine the details of the cross-talk between APC and Smad4 in transcriptional regulation of Claudin-1. Our short term goal is to better understand how dysregulation of claudin-1 expression modulates the ability of colon cancer cells to form tumor and further progression. Our long term goal is to develop claudin-1-specific inhibitors that can be delivered specifically to the colon cancer cells and thus to create an anti-CRC drug that is not toxic and inhibits disease progression. We believe such therapeutic interventions can significantly increase survival and quality of life US Veterans who are suffering from colorectal cancer.

Public Health Relevance

Colorectal cancer (CRC) is one of the leading causes of cancer-related morbidity and mortality in the Veterans population. Majority of these patients die due to the disease progression and metastasis. Therefore, therapies that can help prevent disease progression are urgently needed. Claudin-1, a tight junction protein expression is highly upregulated in CRC in a stage- specific manner. Also, mice with colonic Claudin-1overexpression develop more and malignant tumors in the presence of APC mutation. Our aim is to understand how Claudin-1 affects the tumorigenic ability of CRC cells, in order to define the best possible way to harness its use as a target molecule to inhibit CRC-progression. We predict our studies will help unravel novel role of claudin-1 in the regulation of Notch- and Wnt-signaling to regulate CRC-growth &progression through potential regulation of cancer stem cells and will open new therapeutic opportunities.

Agency
National Institute of Health (NIH)
Institute
Veterans Affairs (VA)
Type
Non-HHS Research Projects (I01)
Project #
5I01BX002086-02
Application #
8709811
Study Section
Oncology A (ONCA)
Project Start
2013-07-01
Project End
2017-06-30
Budget Start
2014-07-01
Budget End
2015-06-30
Support Year
2
Fiscal Year
2014
Total Cost
Indirect Cost
Name
Veterans Health Administration
Department
Type
DUNS #
City
Nashville
State
TN
Country
United States
Zip Code
37212
Ahmad, R; Sorrell, M F; Batra, S K et al. (2017) Gut permeability and mucosal inflammation: bad, good or context dependent. Mucosal Immunol 10:307-317
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Ahmad, R; Kumar, B; Chen, Z et al. (2017) Loss of claudin-3 expression induces IL6/gp130/Stat3 signaling to promote colon cancer malignancy by hyperactivating Wnt/?-catenin signaling. Oncogene 36:6592-6604
Ahmad, Rizwan; Rah, Bilal; Bastola, Dhundy et al. (2017) Obesity-induces Organ and Tissue Specific Tight Junction Restructuring and Barrier Deregulation by Claudin Switching. Sci Rep 7:5125
Ahmad, Rizwan; Kumar, Balawant; Pan, Kaichao et al. (2017) HDAC-4 regulates claudin-2 expression in EGFR-ERK1/2 dependent manner to regulate colonic epithelial cell differentiation. Oncotarget 8:87718-87736
Bhat, Ajaz A; Ahmad, Rizwan; Uppada, SrijayaPrakash B et al. (2016) Claudin-1 promotes TNF-?-induced epithelial-mesenchymal transition and migration in colorectal adenocarcinoma cells. Exp Cell Res 349:119-127
Pai, Priya; Rachagani, Satyanarayana; Dhawan, Punita et al. (2016) MUC4 is negatively regulated through the Wnt/?-catenin pathway via the Notch effector Hath1 in colorectal cancer. Genes Cancer 7:154-168
Singh, Amar B; Dhawan, Punita (2015) Claudins and cancer: Fall of the soldiers entrusted to protect the gate and keep the barrier intact. Semin Cell Dev Biol 42:58-65
Bhat, A A; Pope, J L; Smith, J J et al. (2015) Claudin-7 expression induces mesenchymal to epithelial transformation (MET) to inhibit colon tumorigenesis. Oncogene 34:4570-80
Ahmad, R; Chaturvedi, R; Olivares-Villagómez, D et al. (2014) Targeted colonic claudin-2 expression renders resistance to epithelial injury, induces immune suppression, and protects from colitis. Mucosal Immunol 7:1340-53

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