title: Synergistic association of Notch and NFκB signaling and role of Notch signaling in modulating epithelial to mesenchymal transition in colorectal adenocarcinoma.
abstract: Notch1 signaling plays a key role in normal developmental processes and in cancer. The association between Notch activation and development of cancer has been well documented. Notch activation and outcome of the disease depend upon the crosstalk with other regulatory pathways including Nuclear Factor kappa B (NFκB) pathway. In this study, we have investigated the interaction of Notch intracellular domain (NICD) with NFκBp65 in colorectal cancer which resulted in the upregulation of Bcl-xL resulting in the inhibition of apoptosis. Mesenchymal marker Slug expression and down regulation of E-cadherin, an epithelial phenotypic marker were demonstrated in colon cancer tissues. The study was also illustrated by using the gamma secretase inhibitor, N-[N-(3,5-difluorophenacetyl)-L-alanyl]-S-phenylglycine t-butyl ester (DAPT) in HT29 cells. Immunohistochemistry (NICD, NFκBp65, and Slug) and double immunofluorescence analysis (NICD, NFκBp65) revealed that NICD and NFκBp65 were highly expressed in HT29 cells and in tumor tissue compared to normal tissue. Slug and Bcl-xL protein expressions were significantly reduced in DAPT treated HT 29 cells. Immunoprecipitation and dual staining emphasized the strong interaction of NICD with NFκBp65 in adenocarcinoma than in normal tissue. It appeared that Notch1 and NFκB could independently contribute to tumor progression. However, their interaction and synergism might be the determinants that would affect the outcome of the disease and therapeutic interventions.
authors.affiliation: Unit of Biochemistry, Department of Zoology, University of Madras, School of Life Sciences, Guindy Campus, Chennai 600 025, Tamil Nadu, India.
authors.forename: Natarajan
authors.initials: N
authors.lastname: Gopalakrishnan
authors.affiliation: Department of Biochemistry, University of Madras, Guindy Campus, Chennai 600 025, Tamil Nadu, India.
authors.forename: Niranjali Devaraj
authors.initials: ND
authors.lastname: Sivasithamparam
authors.affiliation: Unit of Biochemistry, Department of Zoology, University of Madras, School of Life Sciences, Guindy Campus, Chennai 600 025, Tamil Nadu, India. Electronic address: hdrajum@yahoo.com.
authors.forename: Halagowder
authors.initials: H
authors.lastname: Devaraj
mesh_terms: D000230:Adenocarcinoma / Q000378:metabolism / Q000473:pathology*; D015820:Cadherins / Q000378:metabolism; D015179:Colorectal Neoplasms / Q000378:metabolism / Q000473:pathology*; D004151:Dipeptides / Q000494:pharmacology; D058750:Epithelial-Mesenchymal Transition; D019073:HT29 Cells / Q000187:drug effects; D006801:Humans; D017434:Protein Structure, Tertiary; D051881:Receptor, Notch1 / Q000378:metabolism*; D012016:Reference Values; D015398:Signal Transduction; D000071250:Snail Family Transcription Factors; D051996:Transcription Factor RelA / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism; D051020:bcl-X Protein / Q000378:metabolism
chemical_list: C494811:BCL2L1 protein, human; D015820:Cadherins; D004151:Dipeptides; C419410:N-(N-(3,5-difluorophenacetyl)alanyl)phenylglycine tert-butyl ester; C497761:NOTCH1 protein, human; D051881:Receptor, Notch1; C000604407:SNAI1 protein, human; D000071250:Snail Family Transcription Factors; D051996:Transcription Factor RelA; D014157:Transcription Factors; D051020:bcl-X Protein
keywords: Apoptosis; Colorectal cancer; DAPT; NFκB; Slug