title: Structure-Based Screen Identification of a Mammalian Ste20-like Kinase 4 (MST4) Inhibitor with Therapeutic Potential for Pituitary Tumors.
abstract: Pituitary tumors of the gonadotrope lineage are often large and invasive, resulting in hypopituitarism. No medical treatments are currently available. Using a combined genetic and genomic screen of individual human gonadotrope pituitary tumor samples, we recently identified the mammalian sterile-20 like kinase 4 (MST4) as a protumorigenic effector, driving increased pituitary cell proliferation and survival in response to a hypoxic microenvironment. To identify novel inhibitors of the MST4 kinase for potential future clinical use, computational-based virtual library screening was used to dock the SelleckChem kinase inhibitor library into the ATP-binding site of the MST4 crystal structure. Several inhibitor candidates were identified with the potential to bind with high affinity. Using a TR-FRET in vitro recombinant kinase assay, hesperadin, initially described as an Aurora kinase inhibitor, exhibited potent inhibition of the MST4 kinase at nanomolar concentrations. The LβT2 gonadotrope pituitary cell hypoxic model was used to test the ability of this inhibitor to antagonize MST4 actions. Under short-term severe hypoxia (1% O2), MST4 protection from hypoxia-induced apoptosis was abrogated in the presence of hesperadin. Similarly, under chronic hypoxia (5%), hesperadin blocked the proliferative and colony-forming actions of MST4 as well as the ability to activate specific downstream signaling and hypoxia-inducible factor-1 effectors. Together, these data identify hesperadin as the first potent, selective inhibitor of the MST4 kinase with the capacity to block pituitary tumor cell growth in a hypoxic microenvironment.
authors.affiliation: Division of Endocrinology, Department of Medicine, University of Colorado School of Medicine, Aurora, Colorado. Research Service, Veterans Affairs Medical Center, Denver, Colorado.
authors.forename: Weipeng
authors.initials: W
authors.lastname: Xiong
authors.affiliation: Department of Pharmaceutical Sciences, University of Colorado School of Pharmacy, Aurora, Colorado.
authors.forename: Christopher J
authors.initials: CJ
authors.lastname: Matheson
authors.affiliation: Division of Endocrinology, Department of Medicine, University of Colorado School of Medicine, Aurora, Colorado. Research Service, Veterans Affairs Medical Center, Denver, Colorado.
authors.forename: Mei
authors.initials: M
authors.lastname: Xu
authors.affiliation: Department of Pharmaceutical Sciences, University of Colorado School of Pharmacy, Aurora, Colorado.
authors.forename: Donald S
authors.initials: DS
authors.lastname: Backos
authors.affiliation: Division of Endocrinology, Department of Medicine, University of Colorado School of Medicine, Aurora, Colorado.
authors.forename: Taylor S
authors.initials: TS
authors.lastname: Mills
authors.affiliation: Division of Endocrinology, Department of Medicine, University of Colorado School of Medicine, Aurora, Colorado.
authors.forename: Smita
authors.initials: S
authors.lastname: Salian-Mehta
authors.affiliation: Division of Endocrinology, Department of Medicine, University of Colorado School of Medicine, Aurora, Colorado. Research Service, Veterans Affairs Medical Center, Denver, Colorado.
authors.forename: Katja
authors.initials: K
authors.lastname: Kiseljak-Vassiliades
authors.affiliation: Department of Pharmaceutical Sciences, University of Colorado School of Pharmacy, Aurora, Colorado.
authors.forename: Philip
authors.initials: P
authors.lastname: Reigan
authors.affiliation: Division of Endocrinology, Department of Medicine, University of Colorado School of Medicine, Aurora, Colorado. Research Service, Veterans Affairs Medical Center, Denver, Colorado. margaret.wierman@ucdenver.edu.
authors.forename: Margaret E
authors.initials: ME
authors.lastname: Wierman
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000737:chemistry* / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects; D001665:Binding Sites; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D004354:Drug Screening Assays, Antitumor; D006801:Humans; D000860:Hypoxia / Q000378:metabolism; D007150:Immunohistochemistry; D007211:Indoles / Q000737:chemistry / Q000494:pharmacology; D008958:Models, Molecular; D008968:Molecular Conformation; D062105:Molecular Docking Simulation; D010911:Pituitary Neoplasms / Q000188:drug therapy / Q000378:metabolism* / Q000473:pathology; D011485:Protein Binding; D047428:Protein Kinase Inhibitors / Q000737:chemistry* / Q000494:pharmacology; D017346:Protein Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000737:chemistry* / Q000378:metabolism*; D021281:Quantitative Structure-Activity Relationship; D013312:Stress, Physiological; D013449:Sulfonamides / Q000737:chemistry / Q000494:pharmacology; D059016:Tumor Microenvironment / Q000187:drug effects; D000099317:Hippo Kinases
chemical_list: D000970:Antineoplastic Agents; D007211:Indoles; D047428:Protein Kinase Inhibitors; D017346:Protein Serine-Threonine Kinases; D013449:Sulfonamides; C430908:STK26 protein, human; D000099317:Hippo Kinases; C474723:hesperadin