title: Design, synthesis, and biological evaluation of substrate-competitive inhibitors of C-terminal Binding Protein (CtBP).
abstract: C-terminal Binding Protein (CtBP) is a transcriptional co-regulator that downregulates the expression of many tumor-suppressor genes. Utilizing a crystal structure of CtBP with its substrate 4-methylthio-2-oxobutyric acid (MTOB) and NAD(+) as a guide, we have designed, synthesized, and tested a series of small molecule inhibitors of CtBP. From our first round of compounds, we identified 2-(hydroxyimino)-3-phenylpropanoic acid as a potent CtBP inhibitor (IC50=0.24μM). A structure-activity relationship study of this compound further identified the 4-chloro- (IC50=0.18μM) and 3-chloro- (IC50=0.17μM) analogues as additional potent CtBP inhibitors. Evaluation of the hydroxyimine analogues in a short-term cell growth/viability assay showed that the 4-chloro- and 3-chloro-analogues are 2-fold and 4-fold more potent, respectively, than the MTOB control. A functional cellular assay using a CtBP-specific transcriptional readout revealed that the 4-chloro- and 3-chloro-hydroxyimine analogues were able to block CtBP transcriptional repression activity. This data suggests that substrate-competitive inhibition of CtBP dehydrogenase activity is a potential mechanism to reactivate tumor-suppressor gene expression as a therapeutic strategy for cancer.
authors.affiliation: Department of Medicinal Chemistry, School of Pharmacy, The Institute for Structural Biology, Drug Discovery, and Development, and the Massey Cancer Center, Virginia Commonwealth University, Richmond, VA 23298, United States.
authors.forename: Sudha
authors.initials: S
authors.lastname: Korwar
authors.affiliation: Division of Hematology, Oncology, & Palliative Care, Department of Human and Molecular Genetics, and the Massey Cancer Center, Virginia Commonwealth University, Richmond, VA 23298, United States.
authors.forename: Benjamin L
authors.initials: BL
authors.lastname: Morris
authors.affiliation: Department of Medicinal Chemistry, School of Pharmacy, The Institute for Structural Biology, Drug Discovery, and Development, and the Massey Cancer Center, Virginia Commonwealth University, Richmond, VA 23298, United States.
authors.forename: Hardik I
authors.initials: HI
authors.lastname: Parikh
authors.affiliation: Department of Medicinal Chemistry, School of Pharmacy, The Institute for Structural Biology, Drug Discovery, and Development, and the Massey Cancer Center, Virginia Commonwealth University, Richmond, VA 23298, United States.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Coover
authors.affiliation: Department of Molecular, Cell, & Cancer Biology, University of Massachusetts Medical School, Worcester, MA 01605, United States.
authors.forename: Tyler W
authors.initials: TW
authors.lastname: Doughty
authors.affiliation: Division of Hematology, Oncology, & Palliative Care, Department of Human and Molecular Genetics, and the Massey Cancer Center, Virginia Commonwealth University, Richmond, VA 23298, United States.
authors.forename: Ian M
authors.initials: IM
authors.lastname: Love
authors.affiliation: Department of Biochemistry & Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605, United States.
authors.forename: Brendan J
authors.initials: BJ
authors.lastname: Hilbert
authors.affiliation: Department of Biochemistry & Molecular Pharmacology, University of Massachusetts Medical School, Worcester, MA 01605, United States.
authors.forename: William E
authors.initials: WE
authors.lastname: Royer
authors.affiliation: Department of Medicinal Chemistry, School of Pharmacy, The Institute for Structural Biology, Drug Discovery, and Development, and the Massey Cancer Center, Virginia Commonwealth University, Richmond, VA 23298, United States.
authors.forename: Glen E
authors.initials: GE
authors.lastname: Kellogg
authors.affiliation: Division of Hematology, Oncology, & Palliative Care, Department of Human and Molecular Genetics, and the Massey Cancer Center, Virginia Commonwealth University, Richmond, VA 23298, United States. Electronic address: steven.grossman@vcuhealth.org.
authors.forename: Steven R
authors.initials: SR
authors.lastname: Grossman
authors.affiliation: Department of Medicinal Chemistry, School of Pharmacy, The Institute for Structural Biology, Drug Discovery, and Development, and the Massey Cancer Center, Virginia Commonwealth University, Richmond, VA 23298, United States. Electronic address: kcellis@vcu.edu.
authors.forename: Keith C
authors.initials: KC
authors.lastname: Ellis
mesh_terms: D000429:Alcohol Oxidoreductases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D000970:Antineoplastic Agents / Q000138:chemical synthesis / Q000737:chemistry / Q000494:pharmacology; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D004268:DNA-Binding Proteins / Q000037:antagonists & inhibitors* / Q000378:metabolism; D015195:Drug Design; D054879:Halogenation; D006801:Humans; D008715:Methionine / Q000031:analogs & derivatives / Q000378:metabolism; D008958:Models, Molecular; D009369:Neoplasms / Q000188:drug therapy / Q000378:metabolism; D010091:Oximes / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology*; D010666:Phenylpropionates / Q000138:chemical synthesis / Q000737:chemistry* / Q000494:pharmacology*; D013329:Structure-Activity Relationship
chemical_list: D000970:Antineoplastic Agents; D004268:DNA-Binding Proteins; D010091:Oximes; D010666:Phenylpropionates; C014632:2-keto-4-methylthiobutyric acid; C035253:3-phenylpropionic acid; D008715:Methionine; D000429:Alcohol Oxidoreductases; C096794:C-terminal binding protein
keywords: C-terminal Binding Protein; CtBP; Dehydrogenase; Hydroxyimine; MTOB; Oxime; Transcriptional co-repressor; Tumor suppressor gene