Common genetic variants associated with melanoma risk or naevus count in patients with wildtype MC1R melanoma.

BACKGROUND: Hypomorphic MC1R variants are the most prevalent genetic determinants of melanoma risk in the white population. However, the genetic background of patients with wildtype (WT) MC1R melanoma is poorly studied. OBJECTIVES: To analyse the role of candidate common genetic variants on the melanoma risk and naevus count in Spanish patients with WT MC1R melanoma. METHODS: We examined 753 individuals with WT MC1R from Spain (497 patients and 256 controls). We used OpenArray reverse-transcriptase polymerase chain reaction to genotype a panel of 221 common genetic variants involved in melanoma, naevogenesis, hormonal pathways and proinflammatory pathways. Genetic models were tested using multivariate logistic regression models. Nonparametric multifactor dimensionality reduction (MDR) was used to detect gene-gene interactions within each biological subgroup of variants. RESULTS: We found that variant rs12913832 in the HERC2 gene, which is associated with blue eye colour, increased melanoma risk in individuals with WT MC1R [odds ratio (OR) 1·97, 95% confidence interval (CI) 1·48-2·63; adjusted P < 0·001; corrected P < 0·001]. We also observed a trend between the rs3798577 variant in the oestrogen receptor alpha gene (ESR1) and a lower naevus count, which was restricted to female patients with WT MC1R (OR 0·51, 95% CI 0·33-0·79; adjusted P = 0·002; corrected P = 0·11). This sex-dependent association was statistically significant in a larger cohort of patients with melanoma regardless of their MC1R status (n = 1497; OR 0·71, 95% CI 0·57-0·88; adjusted P = 0·002), reinforcing the hypothesis of an association between hormonal pathways and susceptibility to melanocytic proliferation. Last, the MDR analysis revealed four genetic combinations associated with melanoma risk or naevus count in patients with WT MC1R. CONCLUSIONS: Our data suggest that epistatic interaction among common variants related to melanocyte biology or proinflammatory pathways might influence melanocytic proliferation in individuals with WT MC1R. What is already known about this topic? Genetic variants in the MC1R gene are the most prevalent melanoma genetic risk factor in the white population. Still, 20-40% of cases of melanoma occur in individuals with wildtype MC1R. Multiple genetic variants have a pleiotropic effect in melanoma and naevogenesis. Additional variants in unexplored pathways might also have a role in melanocytic proliferation in these patients. Epidemiological evidence suggests an association of melanocytic proliferation with hormonal pathways and proinflammatory pathways. What does this study add? Variant rs12913832 in the HERC2 gene, which is associated with blue eye colour, increases the melanoma risk in individuals with wildtype MC1R. Variant rs3798577 in the oestrogen receptor gene is associated with naevus count regardless of the MC1R status in female patients with melanoma. We report epistatic interactions among common genetic variants with a role in modulating the risk of melanoma or the number of naevi in individuals with wildtype MC1R. What is the translational message? We report a potential role of hormonal signalling pathways in melanocytic proliferation, providing a basis for better understanding of sex-based differences observed at the epidemiological level. We show that gene-gene interactions among common genetic variants might be responsible for an increased risk for melanoma development in individuals with a low-risk phenotype, such as darkly pigmented hair and skin.

Oncogenic properties via MAPK signaling of the SOX5-RAF1 fusion gene identified in a wild-type NRAS/BRAF giant congenital nevus.

We recently reported an RAF rearrangement without NRAS or BRAF mutations in lesions from Giant Congenital Melanocytic Nevi (CMN). The new gene fusion involves the 5'-end of the promoter-containing N terminus of the SOX5 gene fused to exons 7-16 of the 3'-end of RAF1 gene leading to a SOX5-RAF1 fusion transcript which loses the auto-inhibitory CR1 domain but retains the complete in-frame coding sequence for the C-Terminal kinase domain of the RAF1. Stable expression of SOX5-RAF1 fusion induced growth factor-independent cell growth in murine hematopoietic Ba/F3 cells and melan-a immortalized melanocytes. Besides, it led to the transformation of both Ba/F3 and NIH 3T3 cells as revealed by colony formation assays. Furthermore, its expression results in MAPK activation assessed by increased levels of p-ERK protein in the cytosol of transduced cells. Treatment with Sorafenib and UO126 inhibited proliferation of Ba/F3-SOX5-RAF1 cells in the absence of IL3 but not the PLX 4720, a specific inhibitor of BRAF. Moreover, the tumorigenic and metastatic capacities of SOX5-RAF1 were assessed in vivo. These results indicate that SOX5-RAF1, a driver event for CMN development, has oncogenic capacity. Thus, sequencing of CMN transcriptomes may lead to the identification of this druggable fusion and interfere with the progression toward melanoma.

DNA Repair and Immune Response Pathways Are Deregulated in Melanocyte-Keratinocyte Co-cultures Derived From the Healthy Skin of Familial Melanoma Patients.

Familial melanoma accounts for 10% of cases, being CDKN2A the main high-risk gene. However, the mechanisms underlying melanomagenesis in these cases remain poorly understood. Our aim was to analyze the transcriptome of melanocyte-keratinocyte co-cultures derived from healthy skin from familial melanoma patients vs. controls, to unveil pathways involved in melanoma development in at-risk individuals. Accordingly, primary melanocyte-keratinocyte co-cultures were established from the healthy skin biopsies of 16 unrelated familial melanoma patients (8 CDKN2A mutant, 8 CDKN2A wild-type) and 7 healthy controls. Whole transcriptome was captured using the SurePrint G3 Human Microarray. Transcriptome analyses included: differential gene expression, functional enrichment, and protein-protein interaction (PPI) networks. We identified a gene profile associated with familial melanoma independently of CDKN2A germline status. Functional enrichment analysis of this profile showed a downregulation of pathways related to DNA repair and immune response in familial melanoma (P < 0.05). In addition, the PPI network analysis revealed a network that consisted of double-stranded DNA repair genes (including BRCA1, BRCA2, BRIP1, and FANCA), immune response genes, and regulation of chromosome segregation. The hub gene was BRCA1. In conclusion, the constitutive deregulation of BRCA1 pathway genes and the immune response in healthy skin could be a mechanism related to melanoma risk.

Influence of germline genetic variants on dermoscopic features of melanoma.

Nevus count is highly determined by inherited variants and has been associated with the origin of melanoma. De novo melanomas (DNMMs) are more prevalent in patients with a low nevus count and have distinctive dermoscopic features than nevus-associated melanomas. We evaluated the impact of nine single nucleotide polymorphisms (SNPs) of MTAP (rs10811629, rs2218220, rs7023329 and rs751173), PLA2G6 (rs132985 and rs2284063), IRF4 (rs12203592), and PAX3 (rs10180903 and rs7600206) genes associated with nevus count and melanoma susceptibility, and the MC1R variants on dermoscopic features of 371 melanomas from 310 patients. All MTAP variants associated with a low nevus count were associated with regression structures (peppering and mixed regression), blue-whitish veil, shiny white structures, and pigment network. SNPs of PLA2G6 (rs132985), PAX3 (rs7600206), and IRF4 (rs12203592) genes were also associated with either shiny white structures or mixed regression (all corrected p-values ≤ .06). Melanomas from red hair color MC1R variants carriers showed lower total dermoscopy score (p-value = .015) and less blotches than melanomas from non-carriers (p-value = .048). Our results provide evidence that germline variants protective for melanoma risk and/or associated with a low nevus count are associated with certain dermoscopic features, more characteristic of de novo and worse prognosis melanomas.

Melanocortin-1 receptor (MC1R) genotypes do not correlate with size in two cohorts of medium-to-giant congenital melanocytic nevi.

Congenital melanocytic nevi (CMN) are cutaneous malformations whose prevalence is inversely correlated with projected adult size. CMN are caused by somatic mutations, but epidemiological studies suggest that germline genetic factors may influence CMN development. In CMN patients from the U.K., genetic variants in MC1R, such as p.V92M and loss-of-function variants, have been previously associated with larger CMN. We analyzed the association of MC1R variants with CMN characteristics in two distinct cohorts of medium-to-giant CMN patients from Spain (N = 113) and from France, Norway, Canada, and the United States (N = 53), similar at the clinical and phenotypical level except for the number of nevi per patient. We found that the p.V92M or loss-of-function MC1R variants either alone or in combination did not correlate with CMN size, in contrast to the U.K. CMN patients. An additional case-control analysis with 259 unaffected Spanish individuals showed a higher frequency of MC1R compound heterozygous or homozygous variant genotypes in Spanish CMN patients compared to the control population (15.9% vs. 9.3%; p = .075). Altogether, this study suggests that MC1R variants are not associated with CMN size in these non-UK cohorts. Additional studies are required to define the potential role of MC1R as a risk factor in CMN development.

Genetic Abnormalities in Large to Giant Congenital Nevi: Beyond NRAS Mutations.

Large and giant congenital melanocytic nevi (CMN) are rare melanocytic lesions mostly caused by postzygotic NRAS alteration. Molecular characterization is usually focused on NRAS and BRAF genes in a unique biopsy sample of the CMN. However, large/giant CMN may exhibit phenotypic differences among distinct areas, and patients differ in features such as presence of multiple CMN or spilus-like lesions. Herein, we have characterized a series of 21 large/giant CMN including patients with spilus-type nevi (9/21 patients, 42.8%). Overall, 53 fresh frozen biopsy samples corresponding to 40 phenotypically characterized areas of large/giant CMNs and 13 satellite lesions were analyzed with a multigene panel and RNA sequencing. Mutational screening showed mutations in 76.2% (16/21) of large/giant CMNs. A NRAS mutation was found in 57.1% (12/21) of patients, and mutations in other genes such as BRAF, KRAS, APC, and MET were detected in 14.3% (3/21) of patients. RNA sequencing showed the fusion transcript ZEB2-ALK and SOX5-RAF1 in large/giant CMN from two patients without missense mutations. Both alterations were not detected in unaffected skin and were detected in different areas of affected skin. These findings suggest that large/giant CMN may result from distinct molecular events in addition to NRAS mutations, including point mutations and fusion transcripts.

Genome-wide linkage analysis in Spanish melanoma-prone families identifies a new familial melanoma susceptibility locus at 11q.

The main genetic factors for familial melanoma remain unknown in >75% of families. CDKN2A is mutated in around 20% of melanoma-prone families. Other high-risk melanoma susceptibility genes explain <3% of families studied to date. We performed the first genome-wide linkage analysis in CDKN2A-negative Spanish melanoma-prone families to identify novel melanoma susceptibility loci. We included 68 individuals from 2, 3, and 6 families with 2, 3, and at least 4 melanoma cases. We detected a locus with significant linkage evidence at 11q14.1-q14.3, with a maximum het-TLOD of 3.449 (rs12285365:A>G), using evidence from multiple pedigrees. The genes contained by the subregion with the strongest linkage evidence were: DLG2, PRSS23, FZD4, and TMEM135. We also detected several regions with suggestive linkage evidence (TLOD >1.9) (1q, 6p, 7p, 11q, 12p, 13q) including the region previously detected in melanoma-prone families from Sweden at 3q29. The family-specific analysis revealed three loci with suggestive linkage evidence for family #1: 1q31.1-q32.1 (max. TLOD 2.447), 6p24.3-p22.3 (max. TLOD 2.409), and 11q13.3-q21 (max. TLOD 2.654). Future next-generation sequencing studies of these regions may allow the identification of new melanoma susceptibility genetic factors.

Prognostic role of tumoral PDL1 expression and peritumoral FoxP3+ lymphocytes in vulvar melanomas.

The prognostic role of PDL1 expression, CD8+ and FoxP3+ lymphocytes in vulvar melanomas has not been studied. We correlated PDL1 expression and CD8+ and FoxP3+ immune infiltrates with clinicopathologic variables and patient outcomes in a series of 75 vulvar melanomas. Tumoral PDL1 expression (>5%) was seen in 23% of cases. By Fisher exact test, PDL1 expression and peritumoral FoxP3+ lymphocytes significantly correlated with less disease-specific death. By linear regression analysis, correlations between tumoral PDL1 expression with the density of tumoral CD8+ and peritumoral CD8+ lymphocytes, tumoral FoxP3+ with tumoral CD8+ lymphocytes, and peritumoral FoxP3+ with peritumoral CD8+ lymphocytes were observed. By univariate analyses, tumor thickness >4 mm predicted poorer progression-free survival, melanoma-specific survival, and overall survival. PDL1 expression >5% and peritumoral CD8+, peritumoral FoxP3+, and tumoral FoxP3+ lymphocytes correlated with better overall survival. By multivariate analyses, high peritumoral FoxP3+ lymphocytes independently predicted better melanoma-specific survival (P = .023), and tumor thickness independently predicted poorer progression-free survival (P = .05) and overall survival (P = .039). In conclusion, our study shows that, independent from tumor thickness, an increased density of peritumoral FoxP3+ lymphocytes may positively impact survival in a subset of vulvar melanomas. Tumoral PDL1 expression correlated with tumoral as well as peritumoral CD8+ and FoxP3+ lymphocytes, supportive of an adaptive immune response. Although the frequency of PDL1 expression is low in vulvar melanoma, its expression may identify a subset of vulvar melanoma that might respond to immunotherapy.

Melanocortin 1 receptor (MC1R) polymorphisms' influence on size and dermoscopic features of nevi.

The melanocortin 1 receptor (MC1R) is a highly polymorphic gene. The loss-of-function MC1R variants ("R") have been strongly associated with red hair color phenotype and an increased melanoma risk. We sequenced the MC1R gene in 175 healthy individuals to assess the influence of MC1R on nevus phenotype. We identified that MC1R variant carriers had larger nevi both on the back [p-value = .016, adjusted for multiple parameters (adj. p-value)] and on the upper limbs (adj. p-value = .007). Specifically, we identified a positive association between the "R" MC1R variants and visible vessels in nevi [p-value = .033, corrected using the FDR method for multiple comparisons (corrected p-value)], dots and globules in nevi (corrected p-value = .033), nevi with eccentric hyperpigmentation (corrected p-value = .033), a high degree of freckling (adj. p-value = .019), and an associative trend with presence of blue nevi (corrected p-value = .120). In conclusion, the MC1R gene appears to influence the nevus phenotype.

AURKA Overexpression Is Driven by FOXM1 and MAPK/ERK Activation in Melanoma Cells Harboring BRAF or NRAS Mutations: Impact on Melanoma Prognosis and Therapy.

The cell cycle-related genes AURKA and FOXM1 are overexpressed in melanoma. We show here that AURKA overexpression is associated with poor prognosis in three independent cohorts of melanoma patients and correlates with the presence of genomic amplification of AURKA locus and BRAFV600E mutation. AURKA overexpression may also be driven by increased promoter activation through elements such as ETS and FOXM1 found within the 5' proximal promoter region. Activated MAPK/ERK signaling pathway mediates robust AURKA promoter activation, thereby knockdown of BRAFV600E and ERK inhibition results in reduced AURKA transcription and expression. We show a positive correlation between FOXM1 and AURKA expression in three independent cohorts of melanoma patients. FOXM1 silencing decreases expression of AURKA and late cell cycle genes in melanoma cells. We further found that FOXM1 expression levels are significantly higher in tumors carrying the BRAFV600E mutation compared with the wild-type BRAF (BRAFwt). Accordingly, the knockdown of BRAFV600E also reduces the expression of FOXM1 in BRAFV600E cells. Moreover, Aurora kinase A and FOXM1 inhibition by either genetic knockdown or pharmacologic inhibitors impair melanoma growth and survival both in culture and in vivo, underscoring their therapeutic value for melanoma patients who fail to benefit from BRAF/MEK signaling inhibition.

A Common Variant in the MC1R Gene (p.V92M) is associated with Alzheimer's Disease Risk.

Despite the recent identification of some novel risk genes for Alzheimer's disease (AD), the genetic etiology of late-onset Alzheimer's disease (LOAD) remains largely unknown. The inclusion of these novel risk genes to the risk attributable to the APOE gene accounts for roughly half of the total genetic variance in LOAD. The evidence indicates that undiscovered genetic factors may contribute to AD susceptibility. In the present study, we sequenced the MC1R gene in 525 Spanish LOAD patients and in 160 controls. We observed that a common MC1R variant p.V92M (rs2228479), not related to pigmentation traits, was present in 72 (14%) patients and 15 (9%) controls and confers increased risk of developing LOAD (OR: 1.99, 95% CI: 1.08-3.64, p = 0.026), especially in those patients whose genetic risk could not be explained by APOE genotype. This association remains and even increased in the subset of 69 patients with typical AD cerebrospinal fluid profile (OR: 3.40 95% CI: 1.40-8.27, p = 0.007). We did not find an association between p.V92M and age of onset of AD. Further studies are necessary to elucidate the role of MC1R in brain cells through the different MC1R pathways.

IRF4 rs12203592 functional variant and melanoma survival.

Inherited genetic factors may modulate clinical outcome in melanoma. Some low-to-medium risk genes in melanoma susceptibility play a role in melanoma outcome. Our aim was to assess the role of the functional IRF4 SNP rs12203592 in melanoma prognosis in two independent sets (Barcelona, N = 493 and Essen, N = 438). Genotype association analyses showed that the IRF4 rs12203592 T allele increased the risk of dying from melanoma in both sets (Barcelona: odds ratio [OR] = 6.53, 95% CI 1.38-30.87, Adj p = 0.032; Essen: OR = 1.68, 95% CI 1.04-2.72, Adj p = 0.035). Survival analyses only showed significance for the Barcelona set (hazard ratio = 4.58, 95% CI 1.11-18.92, Adj p = 0.036). This SNP was also associated with tumour localization, increasing the risk of developing melanoma in head or neck (OR = 1.79, 95% CI 1.07-2.98, Adj p = 0.032) and protecting from developing melanoma in the trunk (OR = 0.59, 95% CI 0.41-0.85, Adj p = 0.004). These findings suggest for the first time that IRF4 rs12203592 plays a role in the modulation of melanoma outcome and confirms its contribution to the localization of the primary tumour.

Genomic analysis and clinical management of adolescent cutaneous melanoma.

Melanoma in young children is rare; however, its incidence in adolescents and young adults is rising. We describe the clinical course of a 15-year-old female diagnosed with AJCC stage IB non-ulcerated primary melanoma, who died from metastatic disease 4 years after diagnosis despite three lines of modern systemic therapy. We also present the complete genomic profile of her tumour and compare this to a further series of 13 adolescent melanomas and 275 adult cutaneous melanomas. A somatic BRAFV600E mutation and a high mutational load equivalent to that found in adult melanoma and composed primarily of C>T mutations were observed. A germline genomic analysis alongside a series of 23 children and adolescents with melanoma revealed no mutations in known germline melanoma-predisposing genes. Adolescent melanomas appear to have genomes that are as complex as those arising in adulthood and their clinical course can, as with adults, be unpredictable.

Genomic expression differences between cutaneous cells from red hair color individuals and black hair color individuals based on bioinformatic analysis.

The MC1R gene plays a crucial role in pigmentation synthesis. Loss-of-function MC1R variants, which impair protein function, are associated with red hair color (RHC) phenotype and increased skin cancer risk. Cultured cutaneous cells bearing loss-of-function MC1R variants show a distinct gene expression profile compared to wild-type MC1R cultured cutaneous cells. We analysed the gene signature associated with RHC co-cultured melanocytes and keratinocytes by Protein-Protein interaction (PPI) network analysis to identify genes related with non-functional MC1R variants. From two detected networks, we selected 23 nodes as hub genes based on topological parameters. Differential expression of hub genes was then evaluated in healthy skin biopsies from RHC and black hair color (BHC) individuals. We also compared gene expression in melanoma tumors from individuals with RHC versus BHC. Gene expression in normal skin from RHC cutaneous cells showed dysregulation in 8 out of 23 hub genes (CLN3, ATG10, WIPI2, SNX2, GABARAPL2, YWHA, PCNA and GBAS). Hub genes did not differ between melanoma tumors in RHC versus BHC individuals. The study suggests that healthy skin cells from RHC individuals present a constitutive genomic deregulation associated with the red hair phenotype and identify novel genes involved in melanocyte biology.

The p. R151C Polymorphism in MC1R Gene Modifies the Age of Onset in Spanish Huntington's Disease Patients.

The expansion of CAG repeats (≥36 CAG) in the HTT gene is the only known genetic cause of Huntington's disease (HD) and the main determinant of the course of the disease. The length of the expanded CAG repeats correlates inversely with the age of onset (AOO) but does not completely determine it. We investigated the role of the melanocortin 1 receptor (MC1R) gene as a modifier factor of AOO in 600 HD patients from Spain. We sequenced the entire region of the MC1R gene and analyzed all the nonsynonymous MC1R genetic variants with a minor allele frequency of at least 0.01 in HD patients. The variability in AOO attributable to the CAG repeats and MC1R polymorphisms was evaluated using a multiple linear regression model. We found that the loss-of-function p. R151C MC1R polymorphism has a significant influence on the AOO (P = 0.004; Bonferroni-corrected P = 0.032) which explains 1.42% of the variance in AOO that cannot be accounted for by the expanded CAG repeat. Our results suggest that the MC1R gene could modify the AOO in Spanish HD patients and encourage the evaluation of loss-of-function MC1R polymorphisms in other HD populations with a higher frequency of these MC1R polymorphisms.

Inherited functional variants of the lymphocyte receptor CD5 influence melanoma survival.

Despite the recent progress in treatment options, malignant melanoma remains a deadly disease. Besides therapy, inherited factors might modulate clinical outcome, explaining in part widely varying survival rates. T-cell effector function regulators on antitumor immune responses could also influence survival. CD5, a T-cell receptor inhibitory molecule, contributes to the modulation of antimelanoma immune responses as deduced from genetically modified mouse models. The CD5 SNPs rs2241002 (NM_014207.3:c.671C > T, p.Pro224Leu) and rs2229177 (NM_014207.3:c.1412C > T, p.Ala471Val) constitute an ancestral haplotype (Pro224-Ala471) that confers T-cell hyper-responsiveness and worsens clinical autoimmune outcome. The assessment of these SNPs on survival impact from two melanoma patient cohorts (Barcelona, N = 493 and Essen, N = 215) reveals that p.Ala471 correlates with a better outcome (OR= 0.57, 95% CI = 0.33-0.99, Adj. p = 0.043, in Barcelona OR = 0.63, 95% CI = 0.40-1.01, Adj. p = 0.051, in Essen). While, p.Leu224 was associated with increased melanoma-associated mortality in both cohorts (OR = 1.87, 95% CI = 1.07-3.24, Adj. p = 0.030 in Barcelona and OR = 1.84, 95% CI = 1.04-3.26, Adj. p = 0.037, in Essen). Furthermore survival analyses showed that the Pro224-Ala471 haplotype in homozygosis improved melanoma survival in the entire set of patients (HR = 0.27, 95% CI 0.11-0.67, Adj. p = 0.005). These findings highlight the relevance of genetic variability in immune-related genes for clinical outcome in melanoma.

Time and tumor type (primary or metastatic) do not influence the detection of BRAF/NRAS mutations in formalin fixed paraffin embedded samples from melanomas.

BACKGROUND: BRAF and NRAS mutation detection is crucial for advanced melanoma treatment. Our aim was to evaluate how different characteristics from formalin-fixed paraffin-embedded (FFPE) samples, age of the block or DNA concentration could influence the success of BRAF and NRAS mutational screening. METHODS: DNA was obtained from 144 FFPE samples (62 primary melanoma, 43 sentinel lymph nodes [SLN] and 39 metastasis). BRAF and NRAS were sequenced by Sanger sequencing. RESULTS: Complete sequencing results were obtained from 75% (108/144) of the samples, and at least one gene was sequenced in 89% (128/144) of them. BRAF was mutated in 55% (29/53) and NRAS in 11% (5/45) of the primary melanomas sequenced. DNA concentration correlated with the tumor area used for DNA extraction (mm2) (adj p-value<0.01, r=0.73). The age of the block did not affect sequencing success. In 60% of samples kept for more than 10 years, both BRAF and NRAS were successfully sequenced. CONCLUSIONS: Preserving sufficient tumor area in FFPE blocks is important. It is necessary to keep the FFPE blocks, no matter their age, as they are necessary to decide the best treatment for the melanoma patient.