PT  - JOURNAL ARTICLE
AU  - M. Michael Dcona
AU  - Priyadarshan K. Damle
AU  - Francisco Zarate-Perez
AU  - Benjamin L. Morris
AU  - Zaid Nawaz
AU  - Michael J. Dennis
AU  - Xiaoyan Deng
AU  - Sudha Korwar
AU  - Sahib J. Singh
AU  - Keith C. Ellis
AU  - William E. Royer
AU  - Dipankar Bandyopadhyay
AU  - Carlos Escalante
AU  - Steven R. Grossman
TI  - Active-Site Tryptophan, the Target of Antineoplastic C-Terminal Binding Protein Inhibitors, Mediates Inhibitor Disruption of CtBP Oligomerization and Transcription Coregulatory Activities
AID  - 10.1124/mol.118.114363
DP  - 2019 Jul 01
TA  - Molecular Pharmacology
PG  - 99--108
VI  - 96
IP  - 1
4099  - http://molpharm.aspetjournals.org/content/96/1/99.short
4100  - http://molpharm.aspetjournals.org/content/96/1/99.full
SO  - Mol Pharmacol2019 Jul 01; 96
AB  - C-terminal binding proteins (CtBP1/2) are oncogenic transcriptional coregulators and dehydrogenases often overexpressed in multiple solid tumors, including breast, colon, and ovarian cancer, and associated with poor survival. CtBPs act by repressing expression of genes responsible for apoptosis (e.g., PUMA, BIK) and metastasis-associated epithelial–mesenchymal transition (e.g., CDH1), and by activating expression of genes that promote migratory and invasive properties of cancer cells (e.g., TIAM1) and genes responsible for enhanced drug resistance (e.g., MDR1). CtBP’s transcriptional functions are also critically dependent on oligomerization and nucleation of transcriptional complexes. Recently, we have developed a family of CtBP dehydrogenase inhibitors, based on the parent 2-hydroxyimino-3-phenylpropanoic acid (HIPP), that specifically disrupt cancer cell viability, abrogate CtBP’s transcriptional function, and block polyp formation in a mouse model of intestinal polyposis that depends on CtBP’s oncogenic functions. Crystallographic analysis revealed that HIPP interacts with CtBP1/2 at a conserved active site tryptophan (W318/324; CtBP1/2) that is unique among eukaryotic D2-dehydrogenases. To better understand the mechanism of action of HIPP-class inhibitors, we investigated the contribution of W324 to CtBP2’s biochemical and physiologic activities utilizing mutational analysis. Indeed, W324 was necessary for CtBP2 self-association, as shown by analytical ultracentrifugation and in vivo cross-linking. Additionally, W324 supported CtBP’s association with the transcriptional corepressor CoREST, and was critical for CtBP2 induction of cell motility. Notably, the HIPP derivative 4-chloro-HIPP biochemically and biologically phenocopied mutational inactivation of CtBP2 W324. Our data support further optimization of W318/W324-interacting CtBP dehydrogenase inhibitors that are emerging as a novel class of cancer cell–specific therapeutic.