CRAF inhibition induces apoptosis in melanoma cells with non-V600E BRAF mutations.
Oncogene
; 28(1): 85-94, 2009 Jan 08.
Article
in En
| MEDLINE
| ID: mdl-18794803
ABSTRACT
Here, we identify a panel of melanoma lines with non-V600E mutations in BRAF. These G469E- and D594G-mutated melanomas were found to exhibit constitutive levels of phospho-extracellular signal-regulated kinase (pERK) and low levels of phospho-mitogen-activated protein kinase/ERK kinase (pMEK) and were resistant to MEK inhibition. Upon treatment with the CRAF inhibitor sorafenib, these lines underwent apoptosis and associated with mitochondrial depolarization and relocalization of apoptosis-inducing factor, whereas the BRAF-V600E-mutated melanomas did not. Studies have shown low-activity mutants of BRAF (G469E/D594G) instead signal through CRAF. Unlike BRAF, CRAF directly regulates apoptosis through mitochondrial localization where it binds to Bcl-2 and phosphorylates BAD. The CRAF inhibitor sorafenib was found to induce a time-dependent reduction in both BAD phosphorylation and Bcl-2 expression in the D594G/G469E lines only. Knockdown of CRAF using a lentiviral shRNA suppressed both Bcl-2 expression and induced apoptosis in the D594G melanoma line but not in a V600E-mutated line. Finally, we showed in a series of xenograft studies that sorafenib was more potent at reducing the growth of tumors with the D594G mutation than those with the V600E mutation. In summary, we have identified a group of melanomas with low-activity BRAF mutations that are reliant upon CRAF-mediated survival activity.
Full text:
1
Collection:
01-internacional
Database:
MEDLINE
Main subject:
Apoptosis
/
Drug Resistance, Neoplasm
/
Proto-Oncogene Proteins c-raf
/
Proto-Oncogene Proteins B-raf
/
Melanoma
Type of study:
Prognostic_studies
Limits:
Humans
Language:
En
Journal:
Oncogene
Journal subject:
BIOLOGIA MOLECULAR
/
NEOPLASIAS
Year:
2009
Document type:
Article
Affiliation country:
United States