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: V Borgdorff, U Rix, G E Winter, M Gridling, A C Müller, F P Breitwieser, C Wagner, J Colinge, K L Bennett, G Superti-Furga, S N Wagner
• Journal: Oncogene (Oncogene) Vol. 33 Issue 19 Pg. 2531-9 (May 08 2014) ISSN: 1476-5594 [Electronic] England
• PMID: 23728343 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• Enzyme Inhibitors
• Indoles
• MITF protein, human
• Microphthalmia-Associated Transcription Factor
• Pyrroles
• RNA, Small Interfering
• AMP-Activated Protein Kinases
• Staurosporine
• midostaurin
• Sunitinib

Topics

• AMP-Activated Protein Kinases (genetics, metabolism)
• Blotting, Western
• Cell Line
• Cell Survival (drug effects)
• Chromatography, Liquid
• Enzyme Inhibitors (pharmacology)
• Fluorescent Antibody Technique
• Humans
• Indoles (pharmacology)
• Mass Spectrometry
• Melanocytes (drug effects, metabolism)
• Melanoma (genetics, metabolism)
• Microphthalmia-Associated Transcription Factor (genetics, metabolism)
• Oncogenes
• Pyrroles (pharmacology)
• RNA Interference
• RNA, Small Interfering
• Staurosporine (analogs & derivatives, pharmacology)
• Sunitinib
• Transfection