Intra-patient heterogeneity was detected in 13.3% of patients for both BRAF and NRAS genes and was not associated with clinico-pathological characteristics of melanomas or metastases.
Stage I-III patients with PIK3CA or NRAS mutations developed more distant metastases (3-year risk in PIK3CA mutated and wild type patients: 23.3% vs 11.5%, P = 0.03; multivariate Hazard ratio (HR) = 3.129, P = 0.003; 3-year risk in NRAS mutated and wild type patients: 40.0% vs 12.2%, P = 0.012; multivariate HR = 5.152, P = 0.003).
Patient-derived cultures of the BRAF mutant/NRAS wild type and BRAF wild type/NRAS mutant metastases showed more homogeneous single-cell gene expression patterns with gene expression modules for proliferation and ABC transporters.
This study aimed to determine if BRAF and NRAS mutant and wild-type tumours differ in their site of first tumour metastasis and anatomical metastatic pathway.
Displacement loop instability occurred significantly more frequently in lymph node metastases and distant metastases of patients with early colorectal cancer onset age <60 years ( p = 0.0122 and p = 0.0129), was found with a significant high rate in a small cohort of TP53-mutated distant metastases ( p = 0.0418), and was associated with TP53 wild-type status of primary tumors ( p = 0.0009), but did not correlate with KRAS, NRAS, BRAF, or PIK3CA mutations.
Therefore, we established a large collection of patient-derived xenografts (PDXs), derived from BRAF(V600E), NRAS(Q61), or BRAF(WT)/NRAS(WT) melanoma metastases prior to treatment with BRAF inhibitor and after resistance had occurred.
We report the first two cases of increasing NRAS mutant allele frequency in melanoma metastases and show that the chromosomal mechanism of this homozygosity is an increased polysomy of chromosome 1.
NRAS mutations were associated with vemurafenib use (p = 0.045) and intracranial metastases (p = 0.036), and MEK1/2 mutations correlated with hepatic progression (p = 0.011).
Transcriptome profiling revealed that transcription factor HMGA2, previously unrecognized in melanoma pathogenesis, is significantly upregulated in primary melanoma and metastases (P-values=1.2 × 10(-7) and 9 × 10(-5)) compared with N. HMGA2 overexpression is associated with BRAF/NRAS mutations (P=0.0002).
Consistency in BRAF/NRAS mutations among paired samples was high for lymph node (91%) and visceral metastases (92.5%), but significantly lower for brain (79%; p = 0.0227) and skin (71%; p = 0.0009) metastases.
The cyclin D1 (CCND1) mRNA level decreased in lesions with multiple metastases and was correlated with both the mRNA levels and mutation state of BRAF and NRAS genes.
Multivariate analysis of this population incorporating age, sex, metastases (M1) category, serum lactate dehydrogenase level, and mutation status confirmed that NRAS mutations are associated independently with decreased overall survival (vs WT; P = .005; hazard ratio, 2.05).
The NRAS codon 61 mutation in follicular carcinomas was positively associated with distant metastases through the entire clinical course of the patients (p<0.05), and RAS mutations were associated with poor overall patient survival (p<0.05).
Mutations were observed in 63% of metastases (48% BRAF; 15% NRAS), a nonsignificant increase in mutation frequency after progression from primary melanoma.
In the present clinico-pathological study of a series of 75 CPTC and FVPTC cases, we evaluated the relative contribution of the morphological features of the tumours and their BRAF and N-RAS status for the occurrence of nodal metastases.
These analyses revealed a moderate to strong phosphorylated Akt expression in 78% (21 of 27) of metastases with NRAS mutations and in 73% (54 of 74) of metastases without NRAS mutations.
NRAS was exclusively mutated in nine of 47 (19%) cell lines and two of 16 (13%) metastases, whereas BRAF was solely mutated in 28 of 47 (60%) cell lines and nine of 16 (56%) metastases.
The present paper describes mutational analysis by polymerase chain reaction-single-strand conformation polymorphism (PCR/SSCP) and nucleotide sequence analysis of the genes coding for the p15, p53 and N-ras proteins in 26 metastases from 25 melanoma patients.