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J Biomol Screen. 2015 Jun;20(5):663-72. doi: 10.1177/1087057114561400. Epub 2014 Dec 4.

Small Molecule, NSC95397, Inhibits the CtBP1-Protein Partner Interaction and CtBP1-Mediated Transcriptional Repression.

Author information

1
Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO, USA.
2
Division of Preclinical Innovation, National Center for Advancing Translational Sciences (NCATS), National Institutes of Health, Rockville, MD, USA.
3
Department of Dermatology, University of Colorado School of Medicine, Aurora, CO, USA.
4
Department of Biochemistry and Molecular Genetics, University of Colorado School of Medicine, Aurora, CO, USA qinghong.zhang@ucdenver.edu marc.ferrer@nih.gov rui.zhao@ucdenver.edu.

Abstract

Carboxyl-terminal binding protein (CtBP) is a transcriptional corepressor that suppresses multiple proapoptotic and epithelial genes. CtBP is overexpressed in many human cancers, and its overexpression increases stem cell-like features, epithelial-mesenchymal transition, and cancer cell survival. Knockdown of CtBP also increases apoptosis independent of p53 in cell culture. Therefore, targeting CtBP with small molecules that disrupt its interaction with transcription factor partners may be an effective cancer therapy. To elicit its corepressing effect, CtBP binds to a conserved peptide motif in each transcription factor partner. We developed an AlphaScreen high-throughput screening assay to monitor the interaction between CtBP and E1A (which mimics the interaction between CtBP and its transcriptional partners). We screened the LOPAC library of 1280 bioactive compounds and identified NSC95397, which inhibits the CtBP-E1A interaction (IC50 = 2.9 µM). The inhibitory activity of NSC95397 was confirmed using two secondary assays and a counterscreen. NSC95397 also behaved as a weak substrate of CtBP dehydrogenase activity and did not inhibit another dehydrogenase, lactase dehydrogenase. Finally, NSC95397 was able to disrupt CtBP-mediated transcriptional repression of a target gene. These studies present a new possibility for the development of a therapeutic agent targeting tumors through disrupting the CtBP transcriptional complex.

KEYWORDS:

AlphaScreen; CtBP1; E1A; NSC95397; protein-protein interaction

PMID:
25477201
PMCID:
PMC4486263
DOI:
10.1177/1087057114561400
[Indexed for MEDLINE]
Free PMC Article

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