title: A chemical biology approach identifies AMPK as a modulator of melanoma oncogene MITF.
abstract: The microphthalmia-associated transcription factor (MITF) is indispensable for the viability of melanocytic cells, is an oncogene in melanoma and has a cell type-specific expression pattern. As the modulation of MITF activity by direct chemical targeting remains a challenge, we assessed a panel of drugs for their ability to downregulate MITF expression or activity by targeting its upstream modulators. We found that the multi-kinase inhibitors midostaurin and sunitinib downregulate MITF protein levels. To identify the target molecules shared by both the drugs in melanocytic cells, a chemical proteomic approach was applied and AMP-activated kinase (AMPK) was identified as the relevant target for the observed phenotype. RNA interference and chemical inhibition of AMPK led to a decrease in MITF protein levels. Reduction of MITF protein levels was the result of proteasomal degradation, which was preceded by enhanced phosphorylation of MITF mediated by ERK. As expected, downregulation of MITF protein levels by AMPK inhibition was associated with decreased viability. Together, these results identify AMPK as an important regulator for the maintenance of MITF protein levels in melanocytic cells.
authors.affiliation: 1] Division of Immunology, Allergy and Infectious Diseases, Department of Dermatology, Medical University of Vienna, Vienna, Austria [2] CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria.
authors.forename: V
authors.initials: V
authors.lastname: Borgdorff
authors.affiliation: CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria.
authors.forename: U
authors.initials: U
authors.lastname: Rix
authors.affiliation: CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria.
authors.forename: G E
authors.initials: GE
authors.lastname: Winter
authors.affiliation: CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria.
authors.forename: M
authors.initials: M
authors.lastname: Gridling
authors.affiliation: CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria.
authors.forename: A C
authors.initials: AC
authors.lastname: Müller
authors.affiliation: CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria.
authors.forename: F P
authors.initials: FP
authors.lastname: Breitwieser
authors.affiliation: Division of Immunology, Allergy and Infectious Diseases, Department of Dermatology, Medical University of Vienna, Vienna, Austria.
authors.forename: C
authors.initials: C
authors.lastname: Wagner
authors.affiliation: CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria.
authors.forename: J
authors.initials: J
authors.lastname: Colinge
authors.affiliation: CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria.
authors.forename: K L
authors.initials: KL
authors.lastname: Bennett
authors.affiliation: CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria.
authors.forename: G
authors.initials: G
authors.lastname: Superti-Furga
authors.affiliation: 1] Division of Immunology, Allergy and Infectious Diseases, Department of Dermatology, Medical University of Vienna, Vienna, Austria [2] CeMM Research Center for Molecular Medicine of the Austrian Academy of Sciences, Vienna, Austria.
authors.forename: S N
authors.initials: SN
authors.lastname: Wagner
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*; D015153:Blotting, Western; D002460:Cell Line; D002470:Cell Survival / Q000187:drug effects; D002853:Chromatography, Liquid; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005455:Fluorescent Antibody Technique; D006801:Humans; D007211:Indoles / Q000494:pharmacology; D013058:Mass Spectrometry; D008544:Melanocytes / Q000187:drug effects / Q000378:metabolism*; D008545:Melanoma / Q000235:genetics / Q000378:metabolism*; D051739:Microphthalmia-Associated Transcription Factor / Q000235:genetics / Q000378:metabolism*; D009857:Oncogenes; D011758:Pyrroles / Q000494:pharmacology; D034622:RNA Interference; D034741:RNA, Small Interfering; D019311:Staurosporine / Q000031:analogs & derivatives / Q000494:pharmacology; D000077210:Sunitinib; D014162:Transfection
chemical_list: D004791:Enzyme Inhibitors; D007211:Indoles; C497234:MITF protein, human; D051739:Microphthalmia-Associated Transcription Factor; D011758:Pyrroles; D034741:RNA, Small Interfering; D055372:AMP-Activated Protein Kinases; D019311:Staurosporine; C059539:midostaurin; D000077210:Sunitinib