Differential sensitivity of melanoma cell lines with BRAFV600E mutation to the specific Raf inhibitor PLX4032.

Abstract

Blocking oncogenic signaling induced by the BRAFV600E mutation is a promising approach for melanoma treatment. We tested the anti-tumor effects of a specific inhibitor of Raf protein kinases, PLX4032/RG7204, in melanoma cell lines. PLX4032 decreased signaling through the MAPK pathway only in cell lines with the BRAFV600E mutation. Seven out of 10 BRAFV600E mutant cell lines displayed sensitivity based on cell viability assays and three were resistant at concentrations up to 10 muM. Among the sensitive cell lines, four were highly sensitive with IC50 values below 1 muM, and three were moderately sensitive with IC50 values between 1 and 10 muM. There was evidence of MAPK pathway inhibition and cell cycle arrest in both sensitive and resistant cell lines. Genomic analysis by sequencing, genotyping of close to 400 oncogeninc mutations by mass spectrometry, and SNP arrays demonstrated no major differences in BRAF locus amplification or in other oncogenic events between sensitive and resistant cell lines. However, metabolic tracer uptake studies demonstrated that sensitive cell lines had a more profound inhibition of FDG uptake upon exposure to PLX4032 than resistant cell lines. In conclusion, BRAFV600E mutant melanoma cell lines displayed a range of sensitivities to PLX4032 and metabolic imaging using PET probes can be used to assess sensitivity.

• Authors: Jonas N Søndergaard, Ramin Nazarian, Qi Wang, Deliang Guo, Teli Hsueh, Stephen Mok, Hooman Sazegar, Laura E MacConaill, Jordi G Barretina, Sarah M Kehoe, Narsis Attar, Erika von Euw, Jonathan E Zuckerman, Bartosz Chmielowski, Begoña Comin-Anduix, Richard C Koya, Paul S Mischel, Roger S Lo, Antoni Ribas
• Journal: Journal of translational medicine (J Transl Med) Vol. 8 Pg. 39 (Apr 20 2010) ISSN: 1479-5876 [Electronic] England
• PMID: 20406486 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't)

Chemical References

• Indoles
• Protein Kinase Inhibitors
• Sulfonamides
• Vemurafenib
• Phosphatidylinositol 3-Kinases
• BRAF protein, human
• Proto-Oncogene Proteins B-raf
• Proto-Oncogene Proteins c-akt

Topics

• Amino Acid Substitution (genetics)
• Animals
• Apoptosis (drug effects)
• Cell Cycle (drug effects)
• Cell Line, Tumor
• Cell Survival (drug effects)
• Diagnostic Imaging
• Drug Resistance, Neoplasm (drug effects)
• Genome, Human (genetics)
• Humans
• Indoles (pharmacology)
• MAP Kinase Signaling System (drug effects)
• Melanoma (enzymology, genetics, pathology)
• Mice
• Mutation (genetics)
• Phosphatidylinositol 3-Kinases (metabolism)
• Phosphorylation (drug effects)
• Protein Kinase Inhibitors (pharmacology)
• Proto-Oncogene Proteins B-raf (antagonists & inhibitors, genetics)
• Proto-Oncogene Proteins c-akt (metabolism)
• Sulfonamides (pharmacology)
• Vemurafenib
• Xenograft Model Antitumor Assays