The increase in Bcl-2 expression mediated by mutated ras therefore qualifies as a rational explanation for the enhanced chemoresistance of human melanoma expressing mutated N-Ras.
We have evaluated five real-time ARMS assays: BRAF 1799T>A, [this includes V600E and V600K] and NRAS 182A>G [Q61R] and 181C>A [Q61K] in melanoma, EGFR 2573T>G [L858R], 2235-2249del15 [E746-A750del] in non-small-cell lung cancer, and compared the results to DNA sequencing of the mutation 'hot-spots' in these genes in formalin-fixed paraffin-embedded tumour (FF-PET) DNA.
This study investigated the utility of protein expression phenotyping to provide an integrated assessment of gene expression programs in BRAF/NRASmelanoma which would be useful for prognosis and may predict response to MEK inhibition.
These preliminary results suggest that BRAF and NRAS mutation status should be determined in prospective phase II studies of HSP90 inhibitors in melanoma.
Our results suggest that the combination of BRAF and NRAS mutation analysis with fusion gene detection contributes to diagnosis of malignant melanoma and clear cell sarcoma, and that insulin-like growth factor 1R might be a novel target for the treatment of these two malignancies.
In this study, we identify a novel cytoplasmic intergenic lincRNA (MIRAT), which is upregulated following prolonged MAPK inhibition in NRAS mutant melanoma and modulates MAPK signaling by binding to the MEK scaffold protein IQGAP1.
PLA2G6 rs132985*T was associated with BRAF V600E (OR = 1.32, 95% CI = 1.05-1.67) and BRAF other (OR = 1.82, 95% CI = 1.11-2.98), but not BRAF V600K or NRAS+ melanoma.
NRAS mutations were most frequently detected in acral melanomas (9.3 %), followed by melanomas without chronic sun-induced damage (7.0 %) and mucosal melanomas (4.8 %), and were not detected in melanomas with chronic sun-induced damage.
However, the analysis of the same DNAs for a different polymorphism based on the presence of additional TaqI sites in the variable tandem repeat region of HRAS1 showed that the total frequency of a group of allelic variants, named Tp, was significantly higher in melanoma patients than in normal donors.
Our results, though carried on cell lines, provide a novel insight into the effect of mutations in the B-RAF and N-RAS genes on global gene expression in melanoma and highlight the complexity of mechanisms involved in tumour initiation and maintenance.
The increased apoptotic rates caused by the combination treatment were significantly reduced through siRNA knockdown of ATF4 and BIM, confirming its critical roles in this process.<b>Conclusions:</b> The data presented herein encourage further advanced <i>in vivo</i> and clinical studies to evaluate MEKi in combination with ER stress inducing BRAFi as a strategy to treat rapidly progressing NRAS-mutant melanoma.<i></i>.
As an example, we detail the detection of a point mutation at codon 61 of the human N-ras gene in DNA from a formalin-fixed paraffin-embedded malignant melanoma specimen.
Mutational analysis of human NRAS genes in malignant melanoma: rapid methods for oligonucleotide hybridization and manual and automated direct sequencing of products generated by the polymerase chain reaction.
Each example of an activated ras gene showed a mutation at the 61st codon of the protein, with the exception of one melanoma which showed a mutation at codon 13 of the N-ras gene; (2) all the melanomas displaying an activated ras gene had a similar cell surface phenotype and appear to come from a similar phase of differentiation; (3) 5-6% of noncultured primary and metastatic melanomas have mutated ras genes; (4) no ras gene mutations were found in any precursor lesion, specifically normal nevi and dysplastic nevi; (5) immunoperoxidase analysis of paraffin-embedded specimens indicated no quantitative or qualitative alterations in p21 expression that correlate with tumor progression; (6) there were no observable differences in p21 expression between melanoma cells growing exponentially or in plateau phase, or between melanoma cells with or without ras mutations; nor were any cell kinetic differences found between cells with and without mutated ras genes.