title: Biological Characterization of an Improved Pyrrole-Based Colchicine Site Agent Identified through Structure-Based Design.
abstract: A refined model of the colchicine site on tubulin was used to design an improved analog of the pyrrole parent compound, JG-03-14. The optimized compound, NT-7-16, was evaluated in biological assays that confirm that it has potent activities as a new colchicine site microtubule depolymerizer. NT-7-16 exhibits antiproliferative and cytotoxic activities against multiple cancer cell lines, with IC(50) values of 10-16 nM, and it is able to overcome drug resistance mediated by the expression of P-glycoprotein and the βIII isotype of tubulin. NT-7-16 initiated the concentration-dependent loss of cellular microtubules and caused the formation of abnormal mitotic spindles, leading to mitotic accumulation. The direct interaction of NT-7-16 with purified tubulin was confirmed, and it was more potent than combretastatin A-4 in these assays. Binding studies verified that NT-7-16 binds to tubulin within the colchicine site. The antitumor effects of NT-7-16 were evaluated in an MDA-MB-435 xenograft model and it had excellent activity at concentrations that were not toxic. A second compound, NT-9-21, which contains dichloro moieties in place of the 3,5-dibromo substituents of NT-7-16, had a poorer fit within the colchicine site as predicted by modeling and the Hydropathic INTeractions score. Biological evaluations showed that NT-9-21 has 10-fold lower potency than NT-7-16, confirming the modeling predictions. These studies highlight the value of the refined colchicine-site model and identify a new pyrrole-based colchicine-site agent with potent in vitro activities and promising in vivo antitumor actions.
authors.affiliation: Department of Pharmacology and Cancer Therapy & Research Center, University of Texas Health Science Center at San Antonio, San Antonio, Texas (C.C.R., A.L.R., S.L.M.); Department of Chemistry University of Richmond, Richmond Virginia (N.T., J.T.G.); Department of Medicinal Chemistry and Institute of Structural Biology and Drug Discovery, Virginia Commonwealth University, Richmond, Virginia (C.D., G.E.K.); and Medicinal Chemistry & Drug Discovery, Chesterfield, Missouri (J.A.S.).
authors.forename: Cristina C
authors.initials: CC
authors.lastname: Rohena
authors.affiliation: Department of Pharmacology and Cancer Therapy & Research Center, University of Texas Health Science Center at San Antonio, San Antonio, Texas (C.C.R., A.L.R., S.L.M.); Department of Chemistry University of Richmond, Richmond Virginia (N.T., J.T.G.); Department of Medicinal Chemistry and Institute of Structural Biology and Drug Discovery, Virginia Commonwealth University, Richmond, Virginia (C.D., G.E.K.); and Medicinal Chemistry & Drug Discovery, Chesterfield, Missouri (J.A.S.).
authors.forename: Nakul S
authors.initials: NS
authors.lastname: Telang
authors.affiliation: Department of Pharmacology and Cancer Therapy & Research Center, University of Texas Health Science Center at San Antonio, San Antonio, Texas (C.C.R., A.L.R., S.L.M.); Department of Chemistry University of Richmond, Richmond Virginia (N.T., J.T.G.); Department of Medicinal Chemistry and Institute of Structural Biology and Drug Discovery, Virginia Commonwealth University, Richmond, Virginia (C.D., G.E.K.); and Medicinal Chemistry & Drug Discovery, Chesterfield, Missouri (J.A.S.).
authors.forename: Chenxiao
authors.initials: C
authors.lastname: Da
authors.affiliation: Department of Pharmacology and Cancer Therapy & Research Center, University of Texas Health Science Center at San Antonio, San Antonio, Texas (C.C.R., A.L.R., S.L.M.); Department of Chemistry University of Richmond, Richmond Virginia (N.T., J.T.G.); Department of Medicinal Chemistry and Institute of Structural Biology and Drug Discovery, Virginia Commonwealth University, Richmond, Virginia (C.D., G.E.K.); and Medicinal Chemistry & Drug Discovery, Chesterfield, Missouri (J.A.S.).
authors.forename: April L
authors.initials: AL
authors.lastname: Risinger
authors.affiliation: Department of Pharmacology and Cancer Therapy & Research Center, University of Texas Health Science Center at San Antonio, San Antonio, Texas (C.C.R., A.L.R., S.L.M.); Department of Chemistry University of Richmond, Richmond Virginia (N.T., J.T.G.); Department of Medicinal Chemistry and Institute of Structural Biology and Drug Discovery, Virginia Commonwealth University, Richmond, Virginia (C.D., G.E.K.); and Medicinal Chemistry & Drug Discovery, Chesterfield, Missouri (J.A.S.).
authors.forename: James A
authors.initials: JA
authors.lastname: Sikorski
authors.affiliation: Department of Pharmacology and Cancer Therapy & Research Center, University of Texas Health Science Center at San Antonio, San Antonio, Texas (C.C.R., A.L.R., S.L.M.); Department of Chemistry University of Richmond, Richmond Virginia (N.T., J.T.G.); Department of Medicinal Chemistry and Institute of Structural Biology and Drug Discovery, Virginia Commonwealth University, Richmond, Virginia (C.D., G.E.K.); and Medicinal Chemistry & Drug Discovery, Chesterfield, Missouri (J.A.S.).
authors.forename: Glen E
authors.initials: GE
authors.lastname: Kellogg
authors.affiliation: Department of Pharmacology and Cancer Therapy & Research Center, University of Texas Health Science Center at San Antonio, San Antonio, Texas (C.C.R., A.L.R., S.L.M.); Department of Chemistry University of Richmond, Richmond Virginia (N.T., J.T.G.); Department of Medicinal Chemistry and Institute of Structural Biology and Drug Discovery, Virginia Commonwealth University, Richmond, Virginia (C.D., G.E.K.); and Medicinal Chemistry & Drug Discovery, Chesterfield, Missouri (J.A.S.).
authors.forename: John T
authors.initials: JT
authors.lastname: Gupton
authors.affiliation: Department of Pharmacology and Cancer Therapy & Research Center, University of Texas Health Science Center at San Antonio, San Antonio, Texas (C.C.R., A.L.R., S.L.M.); Department of Chemistry University of Richmond, Richmond Virginia (N.T., J.T.G.); Department of Medicinal Chemistry and Institute of Structural Biology and Drug Discovery, Virginia Commonwealth University, Richmond, Virginia (C.D., G.E.K.); and Medicinal Chemistry & Drug Discovery, Chesterfield, Missouri (J.A.S.). Mooberry@uthscsa.edu.
authors.forename: Susan L
authors.initials: SL
authors.lastname: Mooberry
mesh_terms: D000818:Animals; D001665:Binding Sites / Q000502:physiology; D003078:Colchicine / Q000737:chemistry / Q000378:metabolism*; D018360:Crystallography, X-Ray; D005260:Female; D006367:HeLa Cells; D006801:Humans; D051379:Mice; D008819:Mice, Nude; D062105:Molecular Docking Simulation / Q000379:methods*; D011758:Pyrroles / Q000737:chemistry / Q000378:metabolism*; D013329:Structure-Activity Relationship; D014404:Tubulin / Q000737:chemistry / Q000378:metabolism*
chemical_list: D011758:Pyrroles; D014404:Tubulin; D003078:Colchicine