Charakterisierung der physiologischen und onkogenen Funktion von STK33, einer Serin/Threonin-Kinase mit Bedeutung für die KRAS-vermittelte Tumorentstehung
Zusammenfassung der Projektergebnisse
The identification of genes that are essential for the initiation and/or maintenance of malignant tumors has the potential to contribute to the development of new, molecularly targeted therapies. However, many oncogenes, such as mutant KRAS, cannot be inhibited directly. Oncogenic mutations may also lead to secondary dependencies on genes that are not structurally altered, which provides alternative ways for the development of genotype-specific drugs. We previously uncovered that the uncharacterized serine/threonine protein kinase STK33 is required by human cancer cells that are dependent on mutant KRAS. Rational development of STK33 inhibitors requires understanding of the mechanisms by which STK33 promotes cancer cell survival as well as insight into the role of STK33 in normal physiology. We therefore aim to characterize the physiological and oncogenic function of STK33 using various approaches and model systems. First, by using mass spectrometry to determine the STK33 interactome, we discoved that the HSP90/CDC37 chaperone complex binds to and stabilizes STK33 in human cancer cells, and pharmacologic inhibition of HSP90 induced proteasomemediated degradation of STK33 in human cancer cells and triggered apoptosis preferentially in KRAS mutant cells in an STK33-dependent manner. Since several HSP90 inhibitors are currently in clinical development providing the opportunity to test their activity in cancer patients with KRAS mutant tumors, we prospectively investigated resistance mechanisms of HSP90 inhibitors, and revealed two mechanisms of resistance to pharmacologic HSP90 blockade that can aid in patient selection and guide the development of additional HSP90 inhibitors or rational combination therapies. Second, we determined the global proteome and phosphoproteome by mass spectrometry in response to STK33 depletion, and integrative analysis point to a potential scaffold-like, kinase-independent function of STK33 in regulating small GTPases, cytoskeletal structures and cell migration (project ongoing). Finally, we developed Stk33 knockout mice, which showed successful depletion of full length Stk33 in the testis of mice, resulting in a complete infertility of male mice due to defective differentiation of round spermatids into functional spermatozoa caused by a misformed manchette and subsequent disturbed tail development. Unexpectedly, these mice still expressed a shortened, kinase-dead Stk33 protein in other organs, and we therefore generated a new Stk33 knockout mouse, which is currently used to further determine the physiologic and oncogenic function of Stk33.
Projektbezogene Publikationen (Auswahl)
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Targeting of KRAS mutant tumors by HSP90 inhibitors involves degradation of STK33. J Exp Med 209:697-711, 2012
Azoitei N, Hoffmann CM, Ellegast JM, Ball CR, Obermayer K, Gößele U, Koch B, Faber K, Genze F, Schrader M, Kestler HA, Döhner H, Chiosis G, Glimm H, Fröhling S, Scholl C
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CDX2-driven leukemogenesis involves KLF4 repression and deregulated PPARg signaling. J Clin Invest 123:299-314, 2013
Faber K, Bullinger L, Ragu C, Garding A, Mertens D, Miller C, Martin D, Walcher D, Döhner K, Döhner H, Claus R, Plass C, Sykes SM, Lane SW, Scholl C, Fröhling S
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HSP90 supports tumor growth and angiogenesis through PRKD2 protein stabilization. Cancer Res 74:7125-7136, 2014
Azoitei N, Diepold K, Brunner C, Rouhi A, Genze F, Becher A, Kestler H, van Lint J, Chiosis G, Koren J 3rd, Fröhling S, Scholl C, Seufferlein T
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Requirement for CDK6 in MLL-rearranged acute myeloid leukemia. Blood 124:13-23, 2014
Placke T, Faber K, Nonami A, Putwain SL, Salih HR, Heidel FH, Krämer A, Root DE, Barbie DA, Krivtsov AV, Armstrong SA, Hahn WC, Huntly BJ, Sykes SM, Milsom MD, Scholl C, Fröhling S
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Comparative analysis of KRAS codon 12, 13, 18, 61, and 117 mutations using human MCF10A isogenic cell lines. Sci Rep 5:8535, 2015
Stolze B, Reinhart S, Bulllinger L, Fröhling S, Scholl C
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Prospective identification of resistance mechanisms to HSP90 inhibition in KRAS mutant cancer cells. Oncotarget 8:7678-7690, 2017
Rouhi A, Miller C, Grasedieck S, Reinhart S, Stolze B, Döhner H, Kuchenbauer F, Bullinger L, Fröhling S, Scholl C
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Integrative genomic and transcriptomic analysis of leiomyosarcoma. Nat Commun 9:144, 2018
Chudasama P, Mughal SS, Sanders MA, Hübschmann D, Chung I, Deeg KI, Wong SH, Rabe S, Hlevnjak M, Zapatka M, Ernst A, Kleinheinz K, Schlesner M, Sieverling L, Klink B, Schröck E, Hoogenboezem RM, Kasper B, Heilig CE, Egerer G, Wolf S, von Kalle C, Eils R, Stenzinger A, Weichert W, Glimm H, Gröschel S, Kopp HG, Omlor G, Lehner B, Bauer S, Schimmack S, Ulrich A, Mechtersheimer G, Rippe K, Brors B, Hutter B, Renner M, Hohenberger P, Scholl C, Fröhling S
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RET-mediated autophagy suppression as targetable co-dependence in acute myeloid leukemia. Leukemia, 2018
Rudat S, Pfaus A, Cheng YY, Holtmann J, Ellegast JM, Bühler C, Di Marcantonio D, Martinez E, Göllner S, Wickenhauser C, Müller-Tidow C, Lutz C, Bullinger L, Milsom MD, Sykes SM, Fröhling S, Scholl C
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Stk33 is required for spermatid differentiation and male fertility in mice. Dev Biol 433:84-93, 2018
Martins LR, Bung RK, Koch S, Richter K, Schwarzmüller L, Terhardt D, Kurtulmus B, Niehrs C, Rouhi A, Lohmann I, Pereira G, Fröhling S, Glimm H, Scholl C
