title: Protein kinase inhibitor SU6668 attenuates positive regulation of Gli proteins in cancer and multipotent progenitor cells.
abstract: Observations that Glioma-associated transcription factors Gli1 and Gli2 (Gli1/2), executers of the Sonic Hedgehog (Shh) signaling pathway and targets of the Transforming Growth Factor β (TGF-β) signaling axis, are involved in numerous developmental and pathological processes unveil them as attractive pharmaceutical targets. Unc-51-like serine/threonine kinase Ulk3 has been suggested to play kinase activity dependent and independent roles in the control of Gli proteins in the context of the Shh signaling pathway. This study aimed at investigating whether the mechanism of generation of Gli1/2 transcriptional activators has similarities regardless of the signaling cascade evoking their activation. We also elucidate further the role of Ulk3 kinase in regulation of Gli1/2 proteins and examine SU6668 as an inhibitor of Ulk3 catalytic activity and a compound targeting Gli1/2 proteins in different cell-based experimental models. Here we demonstrate that Ulk3 is required not only for maintenance of basal levels of Gli1/2 proteins but also for TGF-β or Shh dependent activation of endogenous Gli1/2 proteins in human adipose tissue derived multipotent stromal cells (ASCs) and mouse immortalized progenitor cells, respectively. We show that cultured ASCs possess the functional Shh signaling axis and differentiate towards osteoblasts in response to Shh. Also, we demonstrate that similarly to Ulk3 RNAi, SU6668 prevents de novo expression of Gli1/2 proteins and antagonizes the Gli-dependent activation of the gene expression programs induced by either Shh or TGF-β. Our data suggest SU6668 as an efficient inhibitor of Ulk3 kinase allowing manipulation of the Gli-dependent transcriptional outcome.
authors.affiliation: Protobios LLC, Mäealuse 4, Tallinn 12618, Estonia; Cellin Technologies LLC, Mäealuse 4, Tallinn 12618, Estonia. Electronic address: alla.maloverjan@ttu.ee.
authors.forename: Alla
authors.initials: A
authors.lastname: Piirsoo
authors.affiliation: Protobios LLC, Mäealuse 4, Tallinn 12618, Estonia; Department of Gene Technology, Tallinn University of Technology, Akadeemia tee 15, Tallinn 12618, Estonia.
authors.forename: Lagle
authors.initials: L
authors.lastname: Kasak
authors.affiliation: Protobios LLC, Mäealuse 4, Tallinn 12618, Estonia.
authors.forename: Mari-Liis
authors.initials: ML
authors.lastname: Kauts
authors.affiliation: Institute of Technology, University of Tartu, Nooruse 1, 50411 Tartu, Estonia.
authors.forename: Mart
authors.initials: M
authors.lastname: Loog
authors.affiliation: Cellin Technologies LLC, Mäealuse 4, Tallinn 12618, Estonia.
authors.forename: Kairit
authors.initials: K
authors.lastname: Tints
authors.affiliation: Cellin Technologies LLC, Mäealuse 4, Tallinn 12618, Estonia.
authors.forename: Piia
authors.initials: P
authors.lastname: Uusen
authors.affiliation: Protobios LLC, Mäealuse 4, Tallinn 12618, Estonia.
authors.forename: Toomas
authors.initials: T
authors.lastname: Neuman
authors.affiliation: Department of Gene Technology, Tallinn University of Technology, Akadeemia tee 15, Tallinn 12618, Estonia.
authors.forename: Marko
authors.initials: M
authors.lastname: Piirsoo
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects; D002478:Cells, Cultured; D018507:Gene Expression Regulation, Developmental / Q000187:drug effects; D053823:Hedgehog Proteins / Q000378:metabolism*; D006801:Humans; D007211:Indoles / Q000494:pharmacology; D051741:Kruppel-Like Transcription Factors / Q000096:biosynthesis / Q000378:metabolism*; D007963:Leukocytes, Mononuclear / Q000166:cytology / Q000378:metabolism; D051379:Mice; D039902:Multipotent Stem Cells / Q000187:drug effects; D009369:Neoplasms / Q000378:metabolism* / Q000473:pathology; D009687:Nuclear Proteins / Q000096:biosynthesis / Q000378:metabolism*; D000078183:Oxindoles; D011422:Propionates; D017346:Protein Serine-Threonine Kinases / Q000096:biosynthesis / Q000378:metabolism; D011758:Pyrroles / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects; D014157:Transcription Factors / Q000096:biosynthesis / Q000378:metabolism*; D016212:Transforming Growth Factor beta / Q000096:biosynthesis / Q000378:metabolism*; D000071676:Zinc Finger Protein GLI1; D000075746:Zinc Finger Protein Gli2
chemical_list: C400551:GLI1 protein, human; C082593:GLI2 protein, human; D053823:Hedgehog Proteins; D007211:Indoles; D051741:Kruppel-Like Transcription Factors; D009687:Nuclear Proteins; D000078183:Oxindoles; D011422:Propionates; D011758:Pyrroles; C509239:SHH protein, human; D014157:Transcription Factors; D016212:Transforming Growth Factor beta; D000071676:Zinc Finger Protein GLI1; D000075746:Zinc Finger Protein Gli2; C412603:orantinib; D017346:Protein Serine-Threonine Kinases; C547386:ULK3 protein, human
keywords: Differentiation; Gli proteins; Inhibitor; Multipotent cells; Signal transduction