Phosphoproteomics of MAPK inhibition in BRAF-mutated cells and a role for the lethal synergism of dual BRAF and CK2 inhibition.

Abstract

Activating mutations in the MAPK pathway are prevalent drivers of several cancers. The chief consequence of these mutations is a hyperactive ERK1/2 MAPK able to promote cell proliferation, producing a critical hallmark of metastatic disease. The biochemistry of the ERK pathway is well characterized; however, how the pathway achieves different outcomes in the face of genetic aberrations of cancer and subsequent treatment with chemical inhibitors is not clear. To investigate this, we used mass spectrometry to complete a global phosphoproteomic analysis of a BRAFV600E thyroid cancer cell line (SW1736) after treatment with the mutation-selective inhibitor vemurafenib (PLX4032) and MEK1/2 inhibitor selumetinib (AZD6244). We identified thousands of phosphorylation events orchestrated in BRAFV600E cells and performed kinase landscape analysis to identify putative kinases regulated in response to MAPK blockade. The abundance of phosphopeptides containing consensus motifs for acidophilic kinases increased after short-term inhibition with these compounds. We showed that coinhibition of the pleiotropic acidophilic protein kinase CK2 (CK2) and BRAFV600E synergistically reduced proliferation in patient-derived melanomas and thyroid cancer cells harboring the BRAF lesion. We investigated this mechanism and show a role for CK2 in controlling AKT activation that was not reliant on changes to PTEN or PDK1 phosphorylation. These findings highlight a role for CK2 blockade in potentiating the antiproliferative effects of BRAF and MEK inhibition in BRAF cancers.

• Authors: Robert Parker, Roderick Clifton-Bligh, Mark P Molloy
• Journal: Molecular cancer therapeutics (Mol Cancer Ther) Vol. 13 Issue 7 Pg. 1894-906 (Jul 2014) ISSN: 1538-8514 [Electronic] United States
• PMID: 24825855 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: ©2014 American Association for Cancer Research.

Chemical References

• AZD 6244
• Benzimidazoles
• Indoles
• Protein Kinase Inhibitors
• Sulfonamides
• Vemurafenib
• BRAF protein, human
• Casein Kinase II
• Proto-Oncogene Proteins B-raf
• Proto-Oncogene Proteins c-akt
• Mitogen-Activated Protein Kinases
• MAP Kinase Kinase Kinases

Topics

• Antineoplastic Combined Chemotherapy Protocols (pharmacology)
• Benzimidazoles (administration & dosage, pharmacology)
• Casein Kinase II (antagonists & inhibitors, metabolism)
• Cell Line, Tumor
• Drug Synergism
• Humans
• Indoles (administration & dosage, pharmacology)
• MAP Kinase Kinase Kinases (antagonists & inhibitors, metabolism)
• MAP Kinase Signaling System (drug effects, genetics)
• Melanoma (drug therapy, enzymology, pathology)
• Mitogen-Activated Protein Kinases (antagonists & inhibitors, metabolism)
• Mutation
• Phosphorylation
• Protein Kinase Inhibitors (pharmacology)
• Proteomics (methods)
• Proto-Oncogene Proteins B-raf (genetics, metabolism)
• Proto-Oncogene Proteins c-akt (metabolism)
• Sulfonamides (administration & dosage, pharmacology)
• Thyroid Neoplasms (drug therapy, enzymology, pathology)
• Vemurafenib