Oncotarget

Research Papers:

HDAC-4 regulates claudin-2 expression in EGFR-ERK1/2 dependent manner to regulate colonic epithelial cell differentiation

Rizwan Ahmad, Balawant Kumar, Kaichao Pan, Punita Dhawan and Amar B. Singh _

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Oncotarget. 2017; 8:87718-87736. https://doi.org/10.18632/oncotarget.21190

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Abstract

Rizwan Ahmad1,*, Balawant Kumar1,*, Kaichao Pan1, Punita Dhawan1,2 and Amar B. Singh1,2

1Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, Omaha, NE, USA

2VA Nebraska-Western Iowa Health Care System, Omaha, NE, USA

*These authors have contributed equally to this work

Correspondence to:

Amar B. Singh, email: [email protected]

Keywords: epigenetic regulation, differentiation, colon cancer, cell cycle, claudin

Received: June 02, 2017    Accepted: August 23, 2017    Published: September 23, 2017

ABSTRACT

In normal colon, claudin-2 expression is restricted to the crypt bottom containing the undifferentiated and proliferative colonocytes. Claudin-2 expression is also upregulated in colorectal cancer (CRC) and promotes carcinogenesis. However, cellular mechanism/s regulated by increased claudin-2 expression during the CRC and mechanism/s regulating this increase remain poorly understood. Epigenetic mechanisms help regulate expression of cancer-associated genes and inhibition of Histone Deacetylases (HDACs) induces cell cycle arrest and differentiation. Accordingly, based on a comprehensive in vitro and in vivo analysis we here report that Histone Deacetylases regulate claudin-2 expression in causal association with colonocyte dedifferentiation to promote CRC. Detailed differentiation analyses using colon cancer cells demonstrated inverse association between claudin-2 expression and epithelial differentiation. Genetic manipulation studies revealed the causal role of HDAC-4 in regulating claudin-2 expression during this process. Further analysis identified transcriptional regulation as the underlying mechanism, which was dependent on HDAC-4 dependent modulation of the EGFR-ERK1/2 signaling. Accordingly, colon tumors demonstrated marked upregulation of the HDAC-4/ERK1/2/Claudin-2 signaling. Taken together, we demonstrate a novel role for HDAC-4/EGFR/ERK1/2 signaling in regulating claudin-2 expression to modulate colonocyte differentiation. These findings are of clinical significance and highlight epigenetic regulation as potential mechanism to regulate claudin-2 expression during mucosal pathologies including CRC.


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