MC1R, ASIP, and DNA Repair in Sporadic and Familial Melanoma in a Mediterranean Population

High- and intermediate-risk susceptibility variants in melanoma families from the Mediterranean area: A multicentre cohort from the MelaNostrum Consortium

BACKGROUND

Most of large epidemiological studies on melanoma susceptibility have been conducted on fair skinned individuals (US, Australia and Northern Europe), while Southern European populations, characterized by high UV exposure and dark-skinned individuals, are underrepresented.

OBJECTIVES

We report a comprehensive pooled analysis of established high- and intermediate-penetrance genetic variants and clinical characteristics of Mediterranean melanoma families from the MelaNostrum Consortium.

METHODS

Pooled epidemiological, clinical and genetic (CDKN2A, CDK4, ACD, BAP1, POT1, TERT, and TERF2IP and MC1R genes) retrospective data of melanoma families, collected within the MelaNostrum Consortium in Greece, Italy and Spain, were analysed. Univariate methods and multivariate logistic regression models were used to evaluate the association of variants with characteristics of families and of affected and unaffected family members. Subgroup analysis was performed for each country.

RESULTS

We included 839 families (1365 affected members and 2123 unaffected individuals). Pathogenic/likely pathogenic CDKN2A variants were identified in 13.8% of families. The strongest predictors of melanoma were ≥2 multiple primary melanoma cases (OR 8.1; 95% CI 3.3-19.7), >3 affected members (OR 2.6; 95% CI 1.3-5.2) and occurrence of pancreatic cancer (OR 4.8; 95% CI 2.4-9.4) in the family (AUC 0.76, 95% CI 0.71-0.82). We observed low frequency variants in POT1 (3.8%), TERF2IP (2.5%), ACD (0.8%) and BAP1 (0.3%). MC1R common variants (≥2 variants and ≥2 RHC variants) were associated with melanoma risk (OR 1.4; 95% CI 1.0-2.0 and OR 4.3; 95% CI 1.2-14.6, respectively).

CONCLUSIONS

Variants in known high-penetrance genes explain nearly 20% of melanoma familial aggregation in Mediterranean areas. CDKN2A melanoma predictors were identified with potential clinical relevance for cancer risk assessment.

Fbxo22 inhibits metastasis in triple-negative breast cancer through ubiquitin modification of KDM5A and regulation of H3K4me3 demethylation

The importance of Fbxo22 in carcinogenesis has been highly documented. Here, we discussed downstream regulatory factors of Fbxo22 in TNBC. RNA-sequencing was conducted for identifying differentially expressed genes, followed by construction of a regulatory network. Expression patterns of Fbxo22/KDM5A in TNBC were determined by their correlation with the prognosis analyzed. Then, regulation mechanisms between Fbxo22 and KDM5A as well as between KDM5A and H3K4me3 were assayed. After silencing and overexpression experiments, the significance of Fbxo22 in repressing tumorigenesis in vitro and in vivo was explored. Fbxo22 was poorly expressed, while KDM5A was highly expressed in TNBC. Patients with elevated Fbxo22, decreased KDM5A, or higher p16 had long overall survival. Fbxo22 reduced the levels of KDM5A by ubiquitination. KDM5A promoted histone H3K4me3 demethylation to downregulate p16 expression. Fbxo22 reduced KDM5A expression to enhance p16, thus inducing DNA damage as well as reducing tumorigenesis and metastasis in TNBC. Our study validated FBXO22 as a tumor suppressor in TNBC through ubiquitination of KDM5A and regulation of p16.

Phenotypic and Genetic Features that Differ Between Hereditary and Sporadic Melanoma: Results of a Preliminary Study from a Single Center from Turkey

INTRODUCTION

Most melanoma patients under our supervision lack characteristic phenotypic features for melanoma. In contrast, history of cancers other than melanoma and early age at onset were common. This observation was in favor of hereditary melanoma.

OBJECTIVES

To search for the phenotypic and genetic features that differ between sporadic and hereditary melanomas.

METHODS

In order to reveal phenotypic features, detailed physical exam was conducted to all melanoma patients (N = 43) and for genetic features. CDKN2A and MC1R mutations were detected with Sanger sequencing method. Assignment to hereditary and sporadic groups was done according to the "melanoma cancer syndrome assessment tool". Patients who were diagnosed before the age of 50 were also assigned to the hereditary melanoma group.

RESULTS

Thirty-one patients were assigned to the hereditary group and 12 to the sporadic group. Fair eye color was statistically significantly higher in the sporadic group (P = 0.000). CDKN2A was detected in only 1 patient in the hereditary group. MC1R mutations were found in 12 out of 13 (92.3%) in the hereditary group with a score =3 points, 13 out of 18 (72.2%) in the early age at onset group and 5 out of 12 (41.7%) in the sporadic group (P = 0.024).

CONCLUSIONS

Incidence of CDKN2A mutations in our hereditary group is in accordance with the reported incidences from Mediterranean countries. The difference between the hereditary and sporadic groups in terms of MC1R mutations supports the idea that MC1R genetic testing might help to determine patients with higher risk for hereditary melanoma.

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.

Genetic Variants and Somatic Alterations Associated with MITF-E318K Germline Mutation in Melanoma Patients

The MITF-E318K variant has been implicated in genetic predisposition to cutaneous melanoma. We addressed the occurrence of MITF-E318K and its association with germline status of CDKN2A and MC1R genes in a hospital-based series of 248 melanoma patients including cohorts of multiple, familial, pediatric, sporadic and melanoma associated with other tumors. Seven MITF-E318K carriers were identified, spanning every group except the pediatric patients. Three carriers showed mutated CDKN2A, five displayed MC1R variants, while the sporadic carrier revealed no variants. Germline/tumor whole exome sequencing for this carrier revealed germline variants of unknown significance in ATM and FANCI genes and, in four BRAF-V600E metastases, somatic loss of the MITF wild-type allele, amplification of MITF-E318K and deletion of a 9p21.3 chromosomal region including CDKN2A and MTAP. In silico analysis of tumors from MITF-E318K melanoma carriers in the TCGA Pan-Cancer-Atlas dataset confirmed the association with BRAF mutation and 9p21.3 deletion revealing a common genetic pattern. MTAP was the gene deleted at homozygous level in the highest number of patients. These results support the utility of both germline and tumor genome analysis to define tumor groups providing enhanced information for clinical strategies and highlight the importance of melanoma prevention programs for MITF-E318K patients.

Behavioral and Psychological Outcomes Associated with Skin Cancer Genetic Testing in Albuquerque Primary Care

Simple Summary

Genetic information is publicly available but research examining the best use of such information has not engaged diverse members of the public. We examined public reactions to melanoma genetic testing (using the melanocortin-1 receptor [MC1R] gene) in a study randomizing (like the flip of a coin) 600 diverse primary care patients to a MC1R test offer or usual care. We found that testing did not improve sun protection and skin cancer screening, nor did it lead worry to increase. However, groups less aware of their skin cancer risk, including those who thought their risk was “unlikely” at the start of the study, showed significant improvements in sun protection at three months. In conclusion, testing might be very helpful for certain people who have the most to learn about their risk, who may become motivated to protect themselves from the damaging effects of the sun as a result of skin cancer genetic testing.

Abstract

Public availability of genetic information is increasing; thus, efforts to improve diversity in basic and translational research in genomics is a top priority. Given the increasing U.S. incidence and mortality of melanoma, and the prevalence of common melanocortin-1 receptor (MC1R) gene melanoma risk variants in the general population, we examined genomic testing of MC1R for skin cancer risk in a randomized controlled trial in Albuquerque, New Mexico primary care. Participants were 48% Hispanic and were randomized 5:1 to a MC1R test invitation or usual care. We assessed 3 month sun protection, skin cancer screening, and skin cancer worry outcomes associated with testing, and key effect moderators (e.g., cancer risk perceptions, and skin cancer risk factors). Our findings indicate that the primary outcomes were unchanged by the MC1R test offer, test acceptance, and level of risk feedback. Moderator analyses showed that those with lower risk perception, and those with skin that readily tans, significantly increased their sun protection in response to higher than average risk feedback. Risk feedback did not prompt cancer worry, and average risk feedback did not erode existing sun protection. This study paves the way for the development of tailored strategies to address low skin cancer risk awareness in this understudied context of public health genomics.

Behind the Scene: Exploiting MC1R in Skin Cancer Risk and Prevention

Melanoma and non-melanoma skin cancers (NMSCs) are the most frequent cancers of the skin in white populations. An increased risk in the development of skin cancers has been associated with the combination of several environmental factors (i.e., ultraviolet exposure) and genetic background, including melanocortin-1 receptor (MC1R) status. In the last few years, advances in the diagnosis of skin cancers provided a great impact on clinical practice. Despite these advances, NMSCs are still the most common malignancy in humans and melanoma still shows a rising incidence and a poor prognosis when diagnosed at an advanced stage. Efforts are required to underlie the genetic and clinical heterogeneity of melanoma and NMSCs, leading to an optimization of the management of affected patients. The clinical implications of the impact of germline MC1R variants in melanoma and NMSCs' risk, together with the additional risk conferred by somatic mutations in other peculiar genes, as well as the role of MC1R screening in skin cancers' prevention will be addressed in the current review.

The α-melanocyte-stimulating hormone/melanocortin-1 receptor interaction: A driver of pleiotropic effects beyond pigmentation

Melanocortin-1 Receptor (MC1R), when stimulated by alpha-melanocyte-stimulating hormone (α-MSH), is a driver of eumelanogenesis. Brown/black eumelanin is an effective filter against ultraviolet radiation (UVR) and is a scavenger of free radicals. Several polymorphic variants of MC1R are frequent in red-head people. These polymorphisms reduce the ability of MC1R to promote eumelanogenesis after its activation and spontaneous pheomelanogenesis take place. Since pheomelanin can act as an endogenous photosensitizer, people carrying MC1R polymorphisms are more susceptible to skin cancer. Here, we summarize current knowledge on the biology of MC1R beyond its ability to drive eumelanogenesis. We analyze its capacity to cope with oxidative insult and consequent DNA damage. We describe its ability to transduce through different pathways. We start from the canonical pathway, the cAMP/protein kinase A (PKA) pathway mainly involved in promoting eumelanogenesis, and protection from oxidative damage, and we then move on to describe more recent knowledge concerning ERK pathways, phosphoinositide 3-kinase (PI3K) pathway/AKT, and α-MSH/Peroxisome proliferators activated receptor-γ (PPAR-γ) connection. We describe MC1R polymorphic variants associated with melanoma risk which represent an open window of clinical relevance.

A Framework of Major Tumor-Promoting Signal Transduction Pathways Implicated in Melanoma-Fibroblast Dialogue

Simple Summary

Melanoma cells reside in a complex stromal microenvironment, which is a critical component of disease onset and progression. Mesenchymal or fibroblastic cell type are the most abundant cellular element of tumor stroma. Factors secreted by melanoma cells can activate non-malignant associated fibroblasts to become melanoma associate fibroblasts (MAFs). MAFs promote tumorigenic features by remodeling the extracellular matrix, supporting tumor cells proliferation, neo-angiogenesis and drug resistance. Additionally, environmental factors may contribute to the acquisition of pro-tumorigenic phenotype of fibroblasts. Overall, in melanoma, perturbed tissue homeostasis contributes to modulation of major oncogenic intracellular signaling pathways not only in tumor cells but also in neighboring cells. Thus, targeted molecular therapies need to be considered from the reciprocal point of view of melanoma and stromal cells.

Abstract

The development of a modified stromal microenvironment in response to neoplastic onset is a common feature of many tumors including cutaneous melanoma. At all stages, melanoma cells are embedded in a complex tissue composed by extracellular matrix components and several different cell populations. Thus, melanomagenesis is not only driven by malignant melanocytes, but also by the altered communication between melanocytes and non-malignant cell populations, including fibroblasts, endothelial and immune cells. In particular, cancer-associated fibroblasts (CAFs), also referred as melanoma-associated fibroblasts (MAFs) in the case of melanoma, are the most abundant stromal cells and play a significant contextual role in melanoma initiation, progression and metastasis. As a result of dynamic intercellular molecular dialogue between tumor and the stroma, non-neoplastic cells gain specific phenotypes and functions that are pro-tumorigenic. Targeting MAFs is thus considered a promising avenue to improve melanoma therapy. Growing evidence demonstrates that aberrant regulation of oncogenic signaling is not restricted to transformed cells but also occurs in MAFs. However, in some cases, signaling pathways present opposite regulation in melanoma and surrounding area, suggesting that therapeutic strategies need to carefully consider the tumor–stroma equilibrium. In this novel review, we analyze four major signaling pathways implicated in melanomagenesis, TGF-β, MAPK, Wnt/β-catenin and Hyppo signaling, from the complementary point of view of tumor cells and the microenvironment.

MC1R variants and cutaneous melanoma risk according to histological type, body site, and Breslow thickness: a pooled analysis from the M-SKIP project

Little is known on whether melanocortin 1 receptor (MC1R) associated cutaneous melanoma (CM) risk varies depending on histological subtype and body site, and whether tumour thickness at diagnosis (the most important prognostic factor for CM patients) differs between MC1R variant carriers and wild-type individuals. We studied the association between MC1R variants and CM risk by histological subtype, body site, and Breslow thickness, using the database of the M-SKIP project. We pooled individual data from 15 case-control studies conducted during 2005-2015 in Europe and the USA. Study-specific, multi-adjusted odds ratios were pooled into summary odds ratios (SOR) and 95% confidence intervals (CI) using random-effects models. Six thousand eight hundred ninety-one CM cases and 5555 controls were included. CM risk was increased among MC1R variant carriers vs. wild-type individuals. The increase in risk was comparable across histological subtypes (SOR for any variant vs. wild-type ranged between 1.57 and 1.70, always statistical significant) except acral lentiginous melanoma (ALM), for which no association emerged; and slightly greater on chronically (1.74, 95% CI 1.47-2.07) than intermittently (1.55, 95% CI 1.34-1.78) sun-exposed skin. CM risk was greater for those carrying 'R' vs. 'r' variants; correlated with the number of variants; and was more evident among individuals not showing the red hair colour phenotype. Breslow thickness was not associated with MC1R status. MC1R variants were associated with an increased risk of CM of any histological subtype (except ALM) and occurring on both chronically and intermittently sun-exposed skin.

Effects of the IL6 -174G>C promoter polymorphism and IL-6 serum levels on the progression of cutaneous malignant melanoma

Cutaneous malignant melanoma (CMM) is one of the most immunogenic types of cancer, with a 6-fold higher rate of spontaneous regression than any other malignancy. In addition to responsiveness to different immunotherapies, the immunogenicity of CMM highlights the important role of the host immune system in the response to CMM. The present study aimed to explore the role of two functional promoter polymorphisms [IL6 -174G>C (rs1800785) and TNFA -308G>A (rs1800629)] in the regulation of the genes encoding the pro-inflammatory cytokines interleukin (IL)-6 and tumor necrosis factor-α, specifically in patients with CMM. A total of 76 patients with CMM and 200 control subjects were genotyped using PCR-restriction fragment length polymorphism. The genotype frequencies for both single nucleotide polymorphisms (SNPs) did not differ significantly between the patients and controls (P=0.358 and P=0.810 for IL6 and TNFA, respectively). However, compared with carriers of C-allele genotypes (CG+CC), patients with the IL6 -174GG genotype exhibited more advanced melanoma (Clark scale ≥3; P=0.037) and shorter survival times, particularly those who worked outdoors (in conditions with increased sunlight exposure; P=0.016). Furthermore, the serum IL-6 levels of patients with CMM were significantly higher than those of the control subjects, which were associated with unfavorable blood and serum characteristics and tumor progression (development of new distant metastases; P=0.004), and with a shorter overall survival time (P=0.042). Using a Cox proportional hazard model, the IL6 -174GG genotype was found to be an independent prognostic factor for reduced survival time (P=0.030), together with sex (being male; P=0.004) and occupations with higher exposure to sunlight (P=0.047). In conclusion, the results of the present study indicated that the promoter polymorphisms IL6 -174G>C and TNFA -308G>A are not predisposing factors for CMM. However, the IL6 -174G>C SNP and IL-6 serum concentrations are likely to influence the progression of the disease, and the GG genotype and higher IL-6 serum levels may indicate shorter survival.

Characterization of POU2F1 Gene and Its Potential Impact on the Expression of Genes Involved in Fur Color Formation in Rex Rabbit

The naturally colorful fur of the Rex rabbit is becoming increasingly popular in the modern textile market. Our previous study found that POU class 2 homeobox 1 gene (POU2F1) potentially affects the expression of genes involved in fur color formation in the Rex rabbit, but the function and regulation of POU2F1 has not been reported. In this study, the expression patterns of POU2F1 in Rex rabbits of various colors, as well as in different organs, were analyzed by RT-qPCR. Interference and overexpression of POU2F1 were used to identify the potential effects of POU2F1 on other genes related to fur color formation. The results show that the levels of POU2F1 expression were significantly higher in the dorsal skin of the brown and protein yellow Rex rabbits, compared with that of the black one. POU2F1 mRNAs were widespread in the tissues examined in this study and showed the highest level in the lungs. By transfecting rabbit melanocytes with an POU2F1-overexpression plasmid, we found that the POU2F1 protein was located at the nucleus, and the protein showed the classic characteristics of a transcription factor. In addition, abnormal expression of POU2F1 significantly affected the expression of pigmentation-related genes, including SLC7A11, MITF, SLC24A5, MC1R, and ASIP, revealing the regulatory roles of POU2F1 on pigmentation. The results provide the basis for further exploration of the role of POU2F1 in fur color formation of the Rex rabbit.

Germline mutations predisposing to melanoma

Nearly 15% of melanomas occur in patients with a family history and a subset of these patients have a germline mutation in a melanoma predisposing gene. CDKN2A mutations are responsible for the majority of hereditary melanoma, but many other susceptibility genes have been discovered in recent years, including CDK4, TERT, ACD, TERF2IP, POT1, MITF, MC1R, and BAP1. Additionally, melanoma risk is increased in mixed cancer syndromes caused by mutations in PTEN, BRCA2, BRCA1, RB1, and TP53. While early onset, multiple tumors, and family cancer history remain the most valuable clinical clues for hereditary melanoma, characteristic epithelioid cytology of melanocytic tumors may suggest an underlying BAP1 mutation. Herein, we review the clinical and histopathologic characteristics of melanocytic tumors associated with these germline mutations and discuss the role of genetic counseling.

Evolution of approaches to identify melanoma missing heritability

Introduction: Around 10% of melanoma patients have a positive family history of melanoma and/or related cancers. Although a germline pathogenic variant in a high-risk gene can be identified in up to 40% of these patients, the remaining part of melanoma heritability remains largely unexplained.Areas covered: The aim of this review is to provide an overview of the impact that new technologies and new research approaches had and are having on finding more efficient ways to unravel the missing heritability in melanoma.Expert opinion: High-throughput sequencing technologies have been crucial in increasing the number of genes/loci that might be implicated in melanoma predisposition. However, results from these approaches may have been inferior to the expectations, due to an increase in quantitative information which hasn't been followed at the same speed by an improvement of the methods to correctly interpret these data. Optimal approaches for improving our knowledge on melanoma heritability are currently based on segregation analysis coupled with functional assessment of candidate genes. An improvement of computational methods to infer genotype-phenotype correlations could help address the issue of missing heritability.

The complementary effect of rs1042522 in TP53 and rs1805007 in MC1R is associated with an elevated risk of cutaneous melanoma in Latvian population

Genetic factors serve important roles in melanoma susceptibility. Although much genetic variation has been associated with cutaneous melanoma (CM), little is known about the interactions between genetic variants. The current study investigated the joint effect of rs1042522 in the tumour protein 53 (TP53) gene, rs2279744 in the murine double minute-2 (MDM2) gene and several single nucleotide polymorphisms (SNPs) in the melanocortin 1 receptor (MC1R) gene. All of these genes are interconnected in a single signalling pathway that regulates pigmentation. The current study included 479 individuals, of which, 255 were patients with CM and 224 were controls from the Latvian population. Multifaceted analyses of potential interactions between SNPs were performed, whilst taking into account the pigmentation phenotypes of individuals and tumour characteristics (Breslow thickness and ulceration). Univariate analyses revealed a borderline significant association between rs1042522 in the TP53 gene and CM risk. The results also confirmed a known association with rs1805007 in the MC1R gene. The rs1042522 was also selected as a CM risk factor in multivariate models, suggesting an effect that is independent from and complementary to that of rs1805007. The results indicated that these SNPs need to be taken into account when determining melanoma risk. A strong association between CM and red hair was identified for rs1805007, and rs1805008 in the MC1R gene was mainly associated with red hair. An association was also determined between rs2279744 in the MDM2 gene and brown eye colour. No convincing associations were identified between the analysed SNPs and Breslow thickness of tumours or ulcerations.

Interest and Uptake of MC1R Testing for Melanoma Risk in a Diverse Primary Care Population: A Randomized Clinical Trial

Importance

Germline variants in the MC1R gene are common and confer moderate melanoma risk in those with varied skin types. Approaches to precision skin cancer prevention that include genetic information may promote risk awareness and risk reduction in the general population, including Hispanics.

Objective

To examine prevalence of interest in and uptake of MC1R testing in the general population and examine patterns across demographic and skin cancer risk factors.

Design, Setting, and Participants

A randomized clinical trial examined interest in and uptake of MC1R testing among patients at University of New Mexico General Internal Medicine clinics. Study participants were randomized to either a usual-care condition (National Cancer Institute skin cancer pamphlet for diverse skin types) or an MC1R test offer. Participants were registered clinic patients (≥6 months) and English or Spanish fluent. Of the 600 participants recruited to the overall trial, the present study included those 499 participants randomized to the MC1R test offer.

Interventions

Participants were presented with the option to log onto the study website to read 3 educational modules presenting the rationale, benefits, and drawbacks of MC1R testing.

Main Outcomes and Measures

Main outcomes include website log on (yes vs no), saliva test kit request (yes vs no), and saliva test kit return for MC1R testing (yes vs no). Demographic and skin cancer risk factors were examined as potential predictors of test interest and uptake.

Results

Of the 499 participants (220 [44%] non-Hispanic white, 242 [48%] Hispanic, 396 [79%] female; mean [SD] age, 54 [14.3] years), 232 (46%) elected to learn about MC1R testing by logging onto the website; 204 (88%) of those who logged on decided to request testing; and 167 (82%) of those who requested testing returned the kit. The strongest predictors of website log on were race/ethnicity and education (non-Hispanic whites were more likely to log on [odds ratio for Hispanics vs non-Hispanic whites, 0.5; 95% CI, 0.3-0.7], as were more highly educated individuals [odds ratio for more than high school vs high school or less, 2.7; 95% CI, 1.7-4.3]). The strongest predictor of ordering the test was sunburn history (odds ratio, 5.4; 95% CI, 2.3-12.9 vs no sunburn history).

Conclusions and Relevance

There were moderately high levels of MC1R test interest and uptake in this diverse sample. Addressing potential barriers to testing may be warranted as genomic information becomes integrated into general population approaches to the precision prevention of skin cancer.

Trial Registration

ClinicalTrials.gov identifier: NCT03130569.

Hierarchical modeling of melanocortin 1 receptor variants with skin cancer risk

The human MC1R gene is highly polymorphic among lightly pigmented populations, and several variants in the MC1R gene have been associated with increased risk of both melanoma and nonmelanoma skin cancers. The functional consequences of MC1R gene variants have been studied in vitro and in vivo in postulated causal pathways, such as G-protein-coupled signaling transduction, pigmentation, immune response, inflammatory response, cell proliferation, and extracellular matrix adhesion. In a case-control study nested within the Nurses' Health Study, we utilized hierarchical modeling approaches, incorporating quantitative information from these functional studies, to examine the association between particular MC1R alleles and the risk of skin cancers. Different prior matrices were constructed according to the phenotypic associations in controls, cell surface expression, and enzymatic kinetics. Our results showed the parameter variance estimates of each single nucleotide polymorphism (SNP) were smaller when using a hierarchical modeling approach compared to standard multivariable regression. Estimates of second-level parameters gave information about the relative importance of MC1R effects on different pathways, and odds ratio estimates changed depending on prior models (e.g., the change ranged from -21% to 7% for melanoma risk assessment). In addition, the estimates of prior model hyperparameters in the hierarchical modeling approach allow us to determine the relevance of individual pathways on the risk of each of the skin cancer types. In conclusion, hierarchical modeling provides a useful analytic approach in addition to the widely used conventional models in genetic association studies that can incorporate measures of allelic function.

MC1R variants as melanoma risk factors independent of at-risk phenotypic characteristics: a pooled analysis from the M-SKIP project

PURPOSE

Melanoma represents an important public health problem, due to its high case-fatality rate. Identification of individuals at high risk would be of major interest to improve early diagnosis and ultimately survival. The aim of this study was to evaluate whether MC1R variants predicted melanoma risk independently of at-risk phenotypic characteristics.

MATERIALS AND METHODS

Data were collected within an international collaboration - the M-SKIP project. The present pooled analysis included data on 3,830 single, primary, sporadic, cutaneous melanoma cases and 2,619 controls from seven previously published case-control studies. All the studies had information on MC1R gene variants by sequencing analysis and on hair color, skin phototype, and freckles, ie, the phenotypic characteristics used to define the red hair phenotype.

RESULTS

The presence of any MC1R variant was associated with melanoma risk independently of phenotypic characteristics (OR 1.60; 95% CI 1.36-1.88). Inclusion of MC1R variants in a risk prediction model increased melanoma predictive accuracy (area under the receiver-operating characteristic curve) by 0.7% over a base clinical model (P=0.002), and 24% of participants were better assessed (net reclassification index 95% CI 20%-30%). Subgroup analysis suggested a possibly stronger role of MC1R in melanoma prediction for participants without the red hair phenotype (net reclassification index: 28%) compared to paler skinned participants (15%).

CONCLUSION

The authors suggest that measuring the MC1R genotype might result in a benefit for melanoma prediction. The results could be a valid starting point to guide the development of scientific protocols assessing melanoma risk prediction tools incorporating the MC1R genotype.

Ultraviolet Radiations: Skin Defense-Damage Mechanism

UV-radiations are the invisible part of light spectra having a wavelength between visible rays and X-rays. Based on wavelength, UV rays are subdivided into UV-A (320-400 nm), UV-B (280-320 nm) and UV-C (200-280 nm). Ultraviolet rays can have both harmful and beneficial effects. UV-C has the property of ionization thus acting as a strong mutagen, which can cause immune-mediated disease and cancer in adverse cases. Numbers of genetic factors have been identified in human involved in inducing skin cancer from UV-radiations. Certain heredity diseases have been found susceptible to UV-induced skin cancer. UV radiations activate the cutaneous immune system, which led to an inflammatory response by different mechanisms. The first line of defense mechanism against UV radiation is melanin (an epidermal pigment), and UV absorbing pigment of skin, which dissipate UV radiation as heat. Cell surface death receptor (e.g. Fas) of keratinocytes responds to UV-induced injury and elicits apoptosis to avoid malignant transformation. In addition to the formation of photo-dimers in the genome, UV also can induce mutation by generating ROS and nucleotides are highly susceptible to these free radical injuries. Melanocortin 1 receptor (MC1R) has been known to be implicated in different UV-induced damages such as pigmentation, adaptive tanning, and skin cancer. UV-B induces the formation of pre-vitamin D3 in the epidermal layer of skin. UV-induced tans act as a photoprotection by providing a sun protection factor (SPF) of 3-4 and epidermal hyperplasia. There is a need to prevent the harmful effects and harness the useful effects of UV radiations.

Pathophysiology of melanocortin receptors and their accessory proteins

The melanocortin receptors (MCRs) and their accessory proteins (MRAPs) are involved in regulation of a diverse range of endocrine pathways. Genetic variants of these components result in phenotypic variation and disease. The MC1R is expressed in skin and variants in the MC1R gene are associated with ginger hair color. The MC2R mediates the action of ACTH in the adrenal gland to stimulate glucocorticoid production and MC2R mutations result in familial glucocorticoid deficiency (FGD). MC3R and MC4R are involved in metabolic regulation and their gene variants are associated with severe pediatric obesity, whereas the function of MC5R remains to be fully elucidated. MRAPs have been shown to modulate the function of MCRs and genetic variants in MRAPs are associated with diseases including FGD type 2 and potentially early onset obesity. This review provides an insight into recent advances in MCRs and MRAPs physiology, focusing on the disorders associated with their dysfunction.

Characterization of melanoma susceptibility genes in high-risk patients from Central Italy

Genetic susceptibility to cutaneous melanoma has been investigated in Italian high-risk melanoma patients from different geographical regions. CDKN2A, CDK4, and MC1R genes have been screened in most studies, MITF and POT1 were screened in only one study, and none analyzed the TERT promoter. We carried out a mutational analysis of CDKN2A, CDK4 exon 2, POT1 p.S270N, MITF exon 10, MC1R, and the TERT promoter in 106 high-risk patients with familial melanoma (FM) and sporadic multiple primary melanoma (spMPM) from Central Italy and evaluated mutations according to the clinicopathological characteristics of patients and lesions. In FM, CDKN2A mutations were detected in 8.3% of the families, including one undescribed exon 1β mutation (p.T31M), and their prevalence increased with the number of affected relatives within the family. MC1R variants were identified in 65% of the patients and the TERT rs2853669 promoter polymorphism was identified in 58% of the patients. A novel synonymous mutation detected in MITF exon 10 (c.861A>G, p.E287E), although predicted as a splice site mutation by computational tools, could not functionally be confirmed to alter splicing. For spMPM, 3% carried CDKN2A mutations, 79% carried MC1R variants, and 47% carried the TERT rs2853669 promoter polymorphism. MC1R variants were associated with fair skin type and light hair color both in FM and in spMPM, and with a reduction of age at diagnosis in FM patients. Mutations in CDK4 exon 2 and the POT1 p.S270N mutation were not detected. A low frequency of CDKN2A mutations and a high prevalence of MC1R variants characterize high-risk melanoma patients from Central Italy.

Marshaling the Translational Potential of MC1R for Precision Risk Assessment of Melanoma

Melanoma rates have been increasing in the United States, and neither primary (sun protection and avoidance) nor secondary (skin examination) prevention is practiced consistently, even by those with melanoma risk factors. Inherited variation at MC1R is a robust marker for increased risk of melanoma, even among individuals with "sun-resistant" phenotypes. Although MC1R conveys important information about inherited melanoma risk for a broad spectrum of individuals, concerns that MC1R feedback could have negative consequences, including increased distress about melanoma, inappropriate use of health services, and development of a false sense of security, are valid and require empirical examination. The time is right for high-quality research focusing on the translation of MC1R genotype into clinical and public health practice. If studies show MC1R genetic risk screening is effective at motivating behavior change, more melanomas may be detected at earliest stages for which surgical excision is highly curative or a large number of melanomas may be prevented altogether. While other genetic markers for melanoma susceptibility may emerge in the coming years, the burgeoning research agenda on the public health translational potential of MC1R genetic risk screening will inform and usefully advance current and future precision risk assessment of melanoma. Cancer Prev Res; 11(3); 121-4. ©2017 AACR.

Palmitoylation-dependent activation of MC1R prevents melanomagenesis

The melanocortin-1 receptor (MC1R), a G protein-coupled receptor, plays a crucial role in human and mouse pigmentation^1–8. Activation of MC1R in melanocytes by α-melanocyte-stimulating hormone (α-MSH)⁹ stimulates cAMP signaling and melanin production and enhances DNA repair after UV irradiation (UVR)^10–16. Individuals carrying MC1R variants, especially those associated with red hair color, fair skin and poor tanning ability (RHC-variants), are associated with higher risk of melanoma^{5,17,18,19,20}. However, how MC1R activity might be modulated by UV irradiation, why redheads are more prone to developing melanoma, and whether the activity of RHC variants might be restored for therapeutic benefit remain unresolved questions. Here we demonstrate a potential MC1R-targeted intervention strategy to rescue loss-of-function MC1R in MC1R RHC-variants for therapeutic benefit based on activating MC1R protein palmitoylation. Specifically, MC1R palmitoylation, primarily mediated by the protein-acyl transferase (PAT) ZDHHC13, is essential for activating MC1R signaling that triggers increased pigmentation, UVB-induced G1-like cell cycle arrest and control of senescence and melanomagenesis in vitro and in vivo. Using C57BL/6J-MC1R^e/eJ mice expressing MC1R RHC-variants we show that pharmacological activation of palmitoylation rescues the defects of MC1R RHC-variants and prevents melanomagenesis. The results highlight a central role for MC1R palmitoylation in pigmentation and protection against melanoma.

Implementing an Internet-Delivered Skin Cancer Genetic Testing Intervention to Improve Sun Protection Behavior in a Diverse Population: Protocol for a Randomized Controlled Trial

Background

Limited translational genomic research currently exists to guide the availability, comprehension, and appropriate use of personalized genomics in diverse general population subgroups. Melanoma skin cancers are preventable, curable, common in the general population, and disproportionately increasing in Hispanics.

Objective

Variants in the melanocortin-1 receptor (MC1R) gene are present in approximately 50% of the population, are major factors in determining sun sensitivity, and confer a 2-to-3-fold increase in melanoma risk in the general population, even in populations with darker skin. Therefore, feedback regarding MC1R risk status may raise risk awareness and protective behavior in the general population.

Methods

We are conducting a randomized controlled trial examining Internet presentation of the risks and benefits of personalized genomic testing for MC1R gene variants that are associated with increased melanoma risk. We will enroll a total of 885 participants (462 participants are currently enrolled), who will be randomized 6:1 to personalized genomic testing for melanoma risk versus waiting list control. Control participants will be offered testing after outcome assessments. Participants will be balanced across self-reported Hispanic versus non-Hispanic ethnicity (n=750 in personalized genomic testing for melanoma risk arm; n=135 in control arm), and will be recruited from a general population cohort in Albuquerque, New Mexico, which is subject to year-round sun exposure. Baseline surveys will be completed in-person with study staff and follow-up measures will be completed via telephone.

Results

Aim 1 of the trial will examine the personal utility of personalized genomic testing for melanoma risk in terms of short-term (3-month) sun protection and skin screening behaviors, family and physician communication, and melanoma threat and control beliefs (ie, putative mediators of behavior change). We will also examine potential unintended consequences of testing among those who receive average-risk personalized genomic testing for melanoma risk findings, and examine predictors of sun protection at 3 months as the outcome. These findings will be used to develop messages for groups that receive average-risk feedback. Aim 2 will compare rates of test consideration in Hispanics versus non-Hispanics, including consideration of testing pros and cons and registration of a decision to either accept or decline testing. Aim 3 will examine personalized genomic testing for melanoma risk feedback comprehension, recall, satisfaction, and cancer-related distress in those who undergo testing, and whether these outcomes differ by ethnicity (Hispanic vs non-Hispanic), or sociocultural or demographic factors. Final outcome data collection is anticipated to be complete by October 2017, at which point data analysis will commence.

Conclusions

This study has important implications for personalized genomics in the context of melanoma risk, and may be broadly applicable as a model for delivery of personalized genomic feedback for other health conditions.

MC1R signaling. Intracellular partners and pathophysiological implications

The melanocortin-1 receptor (MC1R) preferentially expressed in melanocytes is best known as a key regulator of the synthesis of epidermal melanin pigments. Its paracrine stimulation by keratinocyte-derived melanocortins also activates DNA repair pathways and antioxidant defenses to build a complex, multifaceted photoprotective response. Many MC1R actions rely on cAMP-dependent activation of two transcription factors, MITF and PGC1α, but pleiotropic MC1R signaling also involves activation of mitogen-activated kinases and AKT. MC1R partners such as β-arrestins, PTEN and the E3 ubiquitin ligase MGRN1 differentially regulate these pathways. The MC1R gene is complex and polymorphic, with frequent variants associated with skin phenotypes and increased cancer risk. We review current knowledge of signaling from canonical MC1R, its splice isoforms and natural polymorphic variants. Recently discovered intracellular targets and partners are also discussed, to highlight the diversity of mechanisms that may contribute to normal and pathological variation of pigmentation and sensitivity to solar radiation-induced damage. This article is part of a Special Issue entitled: Melanocortin Receptors - edited by Ya-Xiong Tao.

CDKN2A and MC1R variants found in Cypriot patients diagnosed with cutaneous melanoma

The prevalence of genetic variants associated to cutaneous melanoma (CM) has never been determined within Cypriot melanomas. This study evaluates the frequency of variants in cyclin-dependent kinase inhibitor 2A (CDKN2A) and melanocortin-1 receptor (MC1R) in 32 patients diagnosed with CM. Other characteristics and risk factors were also assessed. CDKN2A p.Ala148Thr was detected in three of 32 patients, while the control group revealed no variations within CDKN2A. MC1R screening in 32 patients revealed the following variations: p.Val60Leu in 11 patients, p.Arg142His in four patients, p.Thr314Thr in one patient, p.Arg160Trp in one patient, p.Val92Met/p.Thr314Thr in one patient and p.Val92Met/p.Arg142His/p.Thr314Thr in one patient. The control group revealed only p.Val60Leu (in 10 of 45 individuals), which is frequently found in general populations. Two unrelated patients carried CDKN2A p.Ala148Thr in combination with MC1R p.Arg142His, suggesting digenic inheritance that may provide evidence of different gene variants acting synergistically to contribute for CM development. This study confirms the presence of CDKN2A and MC1R variants among Cypriot melanomas and supports existing evidence of a role for these variants in susceptibility to melanoma.

Genetic analysis of melanocortin 1 receptor red hair color variants in a Russian population of Eastern Siberia

The melanocortin 1 receptor is a G_s protein-coupled receptor implicated in melanogenesis regulation. The receptor gene is highly polymorphic, which accounts for the association of several of its single-nucleotide polymorphisms (SNPs) with an increased risk of melanoma. The present study aimed to evaluate the distribution of melanocortin 1 receptor gene variants R151C, R160W, and D294H within the Russian population of Eastern Siberia and its association with melanoma development. Melanoma patients (n=95) admitted to Krasnoyarsk Territorial Oncological Center and healthy controls (n=334) were enrolled in the study. A clinical examination of patients was performed to evaluate the phenotypic features of melanoma patients. SNPs were analyzed by real-time PCR. Clinical examination indicated a more frequent occurrence of fair skin type, blue eyes, blonde and red hair, and more frequent localization of freckles on the neck, trunk, and extremities in the melanoma group of patients. The R151C melanocortin 1 receptor gene variant was found in 18% of melanoma patients and associated with an increased likelihood of melanoma development (odds ratio=6.4; 95% confidence interval: 2.8–14.3; P=0.0001). The two remaining variant alleles of the melanocortin 1 receptor gene occurred with low frequency both in controls and in the melanoma group. The R160W SNP was identified neither in controls nor in melanoma patients. The D294H heterozygous variant was observed in 0.3% of individuals in the control group and in 1.1% of the patients in the melanoma group. Such an asymmetric distribution of the melanocortin 1 receptor within red hair color genotypes in the population under study compared with other populations may be because of Russian genetic homogeneity. Carriers of the mutant R151C allele should exercise caution in terms of exposure to the sun to avoid the risk of melanoma development.

The Role of Interleukin-1 in Inflammatory and Malignant Human Skin Diseases and the Rationale for Targeting Interleukin-1 Alpha

Inflammation plays a major role in the induction and progression of several skin diseases. Overexpression of the major epidermal proinflammatory cytokines interleukin (IL) 1 alpha (IL-1α) and 1 beta (IL-1β) is positively correlated with symptom exacerbation and disease progression in psoriasis, atopic dermatitis, neutrophilic dermatoses, skin phototoxicity, and skin cancer. IL-1β and the interleukin-1 receptor I (IL-1RI) have been used as a therapeutic target for some autoinflammatory skin diseases; yet, their system-wide effects limit their clinical usage. Based on the local effects of extracellular IL-1α and its precursor, pro-IL-1α, we hypothesize that this isoform is a promising drug target for the treatment and prevention of many skin diseases. This review provides an overview on IL-1α and IL-β functions, and their contribution to inflammatory and malignant skin diseases. We also discuss the current treatment regimens, and ongoing clinical trials, demonstrating the potential of targeting IL-1α, and not IL-1β, as a more effective strategy to prevent or treat the onset and progression of various skin diseases.

Genetic predisposition to melanoma

Malignant melanoma is a rare, often fatal form of skin cancer with a complex multigenic etiology. The incidence of melanoma is increasing at an alarming rate. A number of heritable factors contribute to a patient's overall melanoma risk, including response to ultraviolet light, nevus number, and pigmentation characteristics, such as eye and hair color. Approximately 5%-10% of melanoma cases are familial, yet the majority of familial cases lack identifiable germ-line mutations in known susceptibility genes. Additionally, most familial melanomas lack germ-line mutations in genes that are commonly mutated in sporadic melanoma. Candidate and systematic genome-wide association studies have led to an improved understanding of the risk factors for melanoma and the identification of susceptibility genes. In this review, we provide an overview of the major risk factors and known genes implicated in familial melanoma susceptibility.

Significance of the Melanocortin 1 and Endothelin B Receptors in Melanocyte Homeostasis and Prevention of Sun-Induced Genotoxicity

The membrane bound melanocortin 1 receptor (MC1R), and the endothelin B receptor (ENDBR) are two G-protein coupled receptors that play important roles in constitutive regulation of melanocytes and their response to ultraviolet radiation (UVR), the main etiological factor for melanoma. The human MC1R is a G_s protein-coupled receptor, which is activated by its agonists α-melanocyte stimulating hormone (α-melanocortin; α-MSH) and adrenocorticotropic hormone (ACTH). The ENDBR is a G_q coupled-receptor, which is activated by Endothelin (ET)-3 during embryonic development, and ET-1 postnatally. Pigmentation and the DNA repair capacity are two major factors that determine the risk for melanoma. Activation of the MC1R by its agonists stimulates the synthesis of eumelanin, the dark brown photoprotective pigment. In vitro studies showed that α-MSH and ET-1 interact synergistically in the presence of basic fibroblast growth factor to stimulate human melanocyte proliferation and melanogenesis, and to inhibit UVR-induced apoptosis. An important function of the MC1R is reduction of oxidative stress and activation of DNA repair pathways. The human MC1R is highly polymorphic, and MC1R variants, particularly those that cause loss of function of the expressed receptor, are associated with increased melanoma risk independently of pigmentation. These variants compromise the DNA repair and antioxidant capacities of human melanocytes. Recently, activation of ENDBR by ET-1 was reported to reduce the induction and enhance the repair of UVR-induced DNA photoproducts. We conclude that α-MSH and ET-1 and their cognate receptors MC1R and ENDBR reduce the risk for melanoma by maintaining genomic stability of melanocytes via modulating the DNA damage response to solar UVR. Elucidating the response of melanocytes to UVR should improve our understanding of the process of melanomagenesis, and lead to effective melanoma chemoprevention, as well as therapeutic strategies.

Melanocortin 1 Receptor: Structure, Function, and Regulation

The melanocortin 1 receptor (MC1R) is a melanocytic Gs protein coupled receptor that regulates skin pigmentation, UV responses, and melanoma risk. It is a highly polymorphic gene, and loss of function correlates with a fair, UV-sensitive, and melanoma-prone phenotype due to defective epidermal melanization and sub-optimal DNA repair. MC1R signaling, achieved through adenylyl cyclase activation and generation of the second messenger cAMP, is hormonally controlled by the positive agonist melanocortin, the negative agonist agouti signaling protein, and the neutral antagonist β-defensin 3. Activation of cAMP signaling up-regulates melanin production and deposition in the epidermis which functions to limit UV penetration into the skin and enhances nucleotide excision repair (NER), the genomic stability pathway responsible for clearing UV photolesions from DNA to avoid mutagenesis. Herein we review MC1R structure and function and summarize our laboratory's findings on the molecular mechanisms by which MC1R signaling impacts NER.

Pigmentary Markers in Danes--Associations with Quantitative Skin Colour, Nevi Count, Familial Atypical Multiple-Mole, and Melanoma Syndrome

To investigate whether pigmentation genes involved in the melanogenic pathway (melanogenesis) contributed to melanoma predisposition, we compared pigmentary genetics with quantitative skin pigmentation measurements, the number of atypical nevi, the total nevus count, and the familial atypical multiple mole and melanoma (FAMMM) syndrome. We typed 32 pigmentary SNP markers and sequenced MC1R in 246 healthy individuals and 116 individuals attending periodic control for malignant melanoma development, 50 of which were diagnosed with FAMMM. It was observed that individuals with any two grouped MC1R variants (missense, NM_002386:c. 456C > A (p.TYR152*), or NM_002386:c.83_84insA (p.Asn29Glnfs*14) had significantly (p<0.001) lighter skin pigmentation of the upper-inner arm than those with none or one MC1R variant. We did not observe any significant association of the MC1R variants with constitutive pigmentation measured on the buttock area. We hypothesize that the effect of MC1R variants on arm pigmentation is primarily reflecting the inability to tan when subjected to UVR. A gender specific effect on skin pigmentation was also observed, and it was found that the skin pigmentation of females on average were darker than that of males (p<0.01). We conclude that MC1R variants are associated with quantitative skin colour in a lightly pigmented Danish population. We did not observe any association between any pigmentary marker and the FAMMM syndrome. We suggest that the genetics of FAMMM is not related to the genetics of the pigmentary pathway.

Germline determinants of clinical outcome of cutaneous melanoma

Cutaneous melanoma (CM) is the most lethal form of skin cancer. Despite the constant increase in melanoma incidence, which is in part due to incremental advances in early diagnostic modalities, mortality rates have not improved over the last decade and for advanced stages remain steadily high. While conventional prognostic biomarkers currently in use find significant utility for predicting overall general survival probabilities, they are not sensitive enough for a more personalized clinical assessment on an individual level. In recent years, the advent of genomic technologies has brought the promise of identification of germline DNA alterations that may associate with CM outcomes and hence represent novel biomarkers for clinical utilization. This review attempts to summarize the current state of knowledge of germline genetic factors studied for their impact on melanoma clinical outcomes. We also discuss ongoing problems and hurdles in validating such surrogates, and we also project future directions in discovery of more powerful germline genetic factors with clinical utility in melanoma prognostication.

Risk factors for keratinocyte skin cancer in patients diagnosed with melanoma, a large retrospective study

BACKGROUND

Melanoma survivors are at an increased risk of developing other malignancies, including keratinocyte skin cancer (KSC). While it is known that many risk factors for melanoma also impact risk of KSC in the general population, no previous study has investigated risk factors for KSC development in melanoma patients.

OBJECTIVE

We assessed associations of personal and clinical characteristics, including skin phenotype and variations in the melanocortin 1 receptor (MC1R) gene, with KSC risk in melanoma patients.

PATIENTS AND METHODS

We used prospective follow-up information on 1200 patients treated for melanoma at the Instituto Valenciano de Oncología, Spain, between 2000 and 2011. We computed hazard ratios and 95% confidence intervals (CIs) for the association of clinical, personal and genetic characteristics with risk of KSC, squamous cell carcinoma (SCC), or basal cell carcinoma (BCC) from Cox proportional hazard models. Five-year cumulative incidence based on competing risk models of SCC, BCC or KSC overall was computed using multivariate subdistribution hazard models. To assess predictive performance of the models, we computed areas under the receiver-operating characteristic curves (AUCs, discriminatory power) using cross-validation.

RESULTS

Median follow-up was 57.2 months; a KSC was detected in 163 patients (13.6%). In multivariable Cox models, age, sex, sunburns, chronic sun exposure, past personal history of non-melanoma skin cancer or other non-cutaneous neoplasia, and the MC1R variants p.D294H and p.R163Q were significantly associated with KSC risk. A cumulative incidence model including age, sex, personal history of KSC, and of other non-cutaneous neoplasia had an AUC of 0.76 (95% CI: 0.71-0.80). When p.D294H and p.R163Q variants were added to the model, the AUC increased to 0.81 (95% CI: 0.77-0.84) (p-value for difference <0.0001).

CONCLUSIONS

In addition to age, sex, skin characteristics, and sun exposure, p.R163Q and p.D294H MC1R variants significantly increased KSC risk among melanoma patients. Our findings may help identify patients who could benefit most from preventive measures.

Indoor tanning and the MC1R genotype: risk prediction for basal cell carcinoma risk in young people

Basal cell carcinoma (BCC) incidence is increasing, particularly in young people, and can be associated with significant morbidity and treatment costs. To identify young individuals at risk of BCC, we assessed existing melanoma or overall skin cancer risk prediction models and built a novel risk prediction model, with a focus on indoor tanning and the melanocortin 1 receptor gene, MC1R. We evaluated logistic regression models among 759 non-Hispanic whites from a case-control study of patients seen between 2006 and 2010 in New Haven, Connecticut. In our data, the adjusted area under the receiver operating characteristic curve (AUC) for a model by Han et al. (Int J Cancer. 2006;119(8):1976-1984) with 7 MC1R variants was 0.72 (95% confidence interval (CI): 0.66, 0.78), while that by Smith et al. (J Clin Oncol. 2012;30(15 suppl):8574) with MC1R and indoor tanning had an AUC of 0.69 (95% CI: 0.63, 0.75). Our base model had greater predictive ability than existing models and was significantly improved when we added ever-indoor tanning, burns from indoor tanning, and MC1R (AUC = 0.77, 95% CI: 0.74, 0.81). Our early-onset BCC risk prediction model incorporating MC1R and indoor tanning extends the work of other skin cancer risk prediction models, emphasizes the value of both genotype and indoor tanning in skin cancer risk prediction in young people, and should be validated with an independent cohort.

Sporadic melanoma in South-Eastern Italy: the impact of melanocortin 1 receptor (MC1R) polymorphism analysis in low-risk people and report of three novel variants

Environmental and genetic risk factors are involved in the development of melanoma. The role of the melanocortin 1 receptor (MC1R) gene has been investigated and differences according to geographic areas have been described. To evaluate the role of some clinical and genetic risk factors in melanoma development, we performed a case-control study involving 101 melanoma patients and 103 controls coming from South-Eastern Italy (Puglia), after achieving informed consent. We confirmed the role of known clinical risk factors for melanoma. Furthermore, 42 MC1R polymorphisms were observed. Three of these variants (L26V, H232L, D294Y) were not previously reported in the literature. Their predicted impact on receptor function was evaluated using bioinformatic tools. We report an overall frequency of MC1R variants in our population higher than in Northern or Central Italy. The most common polymorphism found was V60L, that has been recently reported to spread among South Mediterranean population. This variant influenced phenotypic characteristics of our population while it did not impinge on melanoma risk. An increased risk of melanoma was associated with two or more MC1R variants, when at least one was RHC, compared to people carrying the MC1R consensus sequence or a single MC1R polymorphism. Interestingly, we observed an increased risk of melanoma in subjects with darker skin and lower nevus count, usually considered at low risk, when carrying MC1R polymorphisms.

MC1R variants increased the risk of sporadic cutaneous melanoma in darker-pigmented Caucasians: a pooled-analysis from the M-SKIP project

The MC1R gene is a key regulator of skin pigmentation. We aimed to evaluate the association between MC1R variants and the risk of sporadic cutaneous melanoma (CM) within the M-SKIP project, an international pooled-analysis on MC1R, skin cancer and phenotypic characteristics. Data included 5,160 cases and 12,119 controls from 17 studies. We calculated a summary odds ratio (SOR) for the association of each of the nine most studied MC1R variants and of variants combined with CM by using random-effects models. Stratified analysis by phenotypic characteristics were also performed. Melanoma risk increased with presence of any of the main MC1R variants: the SOR for each variant ranged from 1.47 (95%CI: 1.17-1.84) for V60L to 2.74 (1.53-4.89) for D84E. Carriers of any MC1R variant had a 66% higher risk of developing melanoma compared with wild-type subjects (SOR; 95%CI: 1.66; 1.41-1.96) and the risk attributable to MC1R variants was 28%. When taking into account phenotypic characteristics, we found that MC1R-associated melanoma risk increased only for darker-pigmented Caucasians: SOR (95%CI) was 3.14 (2.06-4.80) for subjects with no freckles, no red hair and skin Type III/IV. Our study documents the important role of all the main MC1R variants in sporadic CM and suggests that they have a direct effect on melanoma risk, independently on the phenotypic characteristics of carriers. This is of particular importance for assessing preventive strategies, which may be directed to darker-pigmented Caucasians with MC1R variants as well as to lightly pigmented, fair-skinned subjects.

Inherited variation at MC1R and ASIP and association with melanoma-specific survival

Melanocortin-1 receptor (MC1R) is a marker of melanoma risk in populations of European ancestry. However, MC1R effects on survival are much less studied. We investigated associations between variation at MC1R and survival in an international, population-based series of single primary melanoma patients enrolled into the Genes, Environment, and Melanoma study. MC1R genotype data was available for 2,200 participants with a first incident primary melanoma diagnosis. We estimated the association of MC1R genotypes with melanoma-specific survival (i.e., death caused by melanoma) and overall survival using COX proportional hazards modeling, adjusting for established prognostic factors for melanoma. We also conducted stratified analyses by Breslow thickness, tumor site, phenotypic index, and age. In addition, we evaluated haplotypes involving polymorphisms near the Agouti signaling protein gene (ASIP) locus for their impacts on survival. Melanoma-specific survival was inversely associated with carriage of MC1R variants in the absence of consensus alleles compared to carriage of at least one consensus allele (hazard ratio (HR) = 0.60; 95% confidence interval (CI): 0.40, 0.90). MC1R results for overall survival were consistent with no association. We did not observe any statistical evidence of heterogeneity of effect estimates in stratified analyses. We observed increased hazard of melanoma-specific death among carriers of the risk haplotype TG near the ASIP locus (HR = 1.37; 95% CI: 0.91, 2.04) when compared to carriers of the most common GG haplotype. Similar results were noted for overall survival. Upon examining the ASIP TG/TG diplotype, we observed considerably increased hazard of melanoma-specific death (HR = 5.11; 95% CI: 1.88, 13.88) compared to carriers of the most common GG/GG diplotype. Our data suggest improved melanoma-specific survival among carriers of two inherited MC1R variants.

MC1R, the cAMP pathway, and the response to solar UV: extending the horizon beyond pigmentation

The melanocortin 1 receptor (MC1R) is a G protein-coupled receptor crucial for the regulation of melanocyte proliferation and function. Upon binding melanocortins, MC1R activates several signaling cascades, notably the cAMP pathway leading to synthesis of photoprotective eumelanin. Polymorphisms in the MC1R gene are a major source of normal variation of human hair color and skin pigmentation, response to ultraviolet radiation (UVR), and skin cancer susceptibility. The identification of a surprisingly high number of MC1R natural variants strongly associated with pigmentary phenotypes and increased skin cancer risk has prompted research on the functional properties of the wild-type receptor and frequent mutant alleles. We summarize current knowledge on MC1R structural and functional properties, as well as on its intracellular trafficking and signaling. We also review the current knowledge about the function of MC1R as a skin cancer, particularly melanoma, susceptibility gene and how it modulates the response of melanocytes to UVR.

A large French case-control study emphasizes the role of rare Mc1R variants in melanoma risk

BACKGROUND

The MC1R gene implicated in melanogenesis and skin pigmentation is highly polymorphic. Several alleles are associated with red hair and fair skin phenotypes and contribute to melanoma risk.

OBJECTIVE

This work aims to assess the effect of different classes of MC1R variants, notably rare variants, on melanoma risk. Methods. MC1R coding region was sequenced in 1131 melanoma patients and 869 healthy controls. MC1R variants were classified as RHC (R) and non-RHC (r). Rare variants (frequency < 1%) were subdivided into two subgroups, predicted to be damaging (D) or not (nD).

RESULTS

Both R and r alleles were associated with melanoma (OR = 2.66 [2.20-3.23] and 1.51 [1.32-1.73]) and had similar population attributable risks (15.8% and 16.6%). We also identified 69 rare variants, of which 25 were novel. D variants were strongly associated with melanoma (OR = 2.38 [1.38-4.15]) and clustered in the same MC1R domains as R alleles (intracellular 2, transmembrane 2 and 7).

CONCLUSION

This work confirms the role of R and r alleles in melanoma risk in the French population and proposes a novel class of rare D variants as important melanoma risk factors. These findings may improve the definition of high-risk subjects that could be targeted for melanoma prevention and screening.

High- and low-penetrance cutaneous melanoma susceptibility genes

The aim of this review is to report the current understanding of the molecular genetics of melanoma predisposition. To date, two high-penetrance melanoma susceptibility genes, cyclin-dependent kinas inhibitor (CDKN)2A on chromosome 9p21 and cyclin-dependent kinase (CDK4) on 12q13, have been identified. Germline inactivating mutations of the CDKN2A gene are the most common cause of inherited susceptibility to melanoma. Worldwide, a few families have been found to harbor CDK4 mutations. However, predisposing alterations to familial melanoma are still unknown in a large proportion of kindreds. Other melanoma susceptibility loci have been mapped through genome-wide linkage analysis, although the putative causal genes at these loci have yet to be identified. Much ongoing research is being focused on the identification of low-penetrance melanoma susceptibility genes that confer a lower melanoma risk with more frequent variations. Specific variants of the MC1R gene have been demonstrated to confer an increase in melanoma risk. In addition, conflicting data are available on other potential low-penetrance genes encoding proteins involved in pigmentation, cell growth and differentiation, DNA repair or detoxifying of metabolites.

Clinical characteristics of patients with cutaneous melanoma according to variants in the melanocortin 1 receptor gene

INTRODUCTION

Patients with cutaneous melanoma who are carriers of polymorphisms in the melanocortin 1 receptor gene (MC1R) have distinctive clinical characteristics. The objective of this study was to determine the clinical characteristics associated with differing degrees of functional impairment of the melanocortin 1 receptor, as determined by the number and type (R and r) of MC1R polymorphisms.

MATERIAL AND METHODS

In total, 1044 consecutive patients with melanoma diagnosed in our hospital after January 2000 were selected from the melanoma database. These patients were divided into 3 groups according to a score based on nonsynonymous MC1R polymorphisms. The frequencies of epidemiologic, phenotypic, and histologic variables and personal and family history of cancer were compared.

RESULTS

Patients with a score of 3 or more were more likely to develop melanoma before the age of 50 years (odds ratio [OR]=1.47), have a tumor on the head or neck (OR=3.04), have a history of basal cell carcinoma or cutaneous squamous cell carcinoma (OR=1.70), have atypical nevi (OR=1.74), and have nevi associated with the melanoma (OR=1.87).

CONCLUSIONS

The use of a scoring system for MC1R polymorphisms allowed us to identify associations between the degree of functional impairment of the melanogenesis pathway and the clinical characteristics of the patients and melanoma presentation.

MC1R gene variants and sporadic malignant melanoma susceptibility in the Canary Islands population

Several MC1R variants are associated with increased risk of malignant melanoma (MM) in a variety of populations. We aim to examine the influence of the MC1R variants (RHC: D84E, R151C, R160W; NRHC: V60L, R163Q and the synonymous polymorphism T314T) on the MM risk in a population from the Canary Islands. Overall, 1,046 Caucasian individuals were included in the study. A thousand of them were genotyped for MC1R variants: 509 were sporadic MM patients and 491 were healthy control subjects from general population. The analysis was adjusted for age, sex, hair colour, eye colour, skin phototype and ancestry. We found that carriers of the R151C and R163Q variants were at an increased risk for melanoma OR 2.76 (1.59-4.78) and OR 5.62 (2.54-12.42), respectively. The risk of carrying RHC variants was 3.04 (1.90-4.86). Current study confirms the increased MM risk for R151C carriers. It also supports the association between R163Q variant and MM risk in the population on the Canary Islands, as opposed to reported on northern populations. These results highlight the importance of the sample population selection in this kind of studies.

Association of genetic variants in CDK6 and XRCC1 with the risk of dysplastic nevi in melanoma-prone families

Dysplastic nevi (DN) is a strong risk factor for cutaneous malignant melanoma (CMM), and it frequently occurs in melanoma-prone families. To identify genetic variants for DN, we genotyped 677 tagSNPs in 38 melanoma candidate genes that are involved in pigmentation, DNA repair, cell cycle control, and melanocyte proliferation pathways in a total of 504 individuals (310 with DN, 194 without DN) from 53 melanoma-prone families (23 CDKN2A mutation positive and 30 negative). Conditional logistic regression, conditioning on families, was used to estimate the association between DN and each SNP separately, adjusted for age, sex, CMM and CDKN2A status. P-values for SNPs in the same gene were combined to yield gene-specific p-values. Two genes, CDK6 and XRCC1, were significantly associated with DN after Bonferroni correction for multiple testing (P=0.0001 and 0.00025, respectively), whereas neither gene was significantly associated with CMM. Associations for CDK6 SNPs were stronger in CDKN2A mutation positive families (rs2079147, P_interaction=0.0033), whereas XRCC1 SNPs had similar effects in mutation-positive and negative families. The association for one of the associated SNPs in XRCC1 (rs25487) was replicated in two independent datasets (random effect meta-analysis: P<0.0001). Our findings suggest that some genetic variants may contribute to DN risk independently of their association with CMM in melanoma-prone families.

UV radiation and the skin

UV radiation (UV) is classified as a "complete carcinogen" because it is both a mutagen and a non-specific damaging agent and has properties of both a tumor initiator and a tumor promoter. In environmental abundance, UV is the most important modifiable risk factor for skin cancer and many other environmentally-influenced skin disorders. However, UV also benefits human health by mediating natural synthesis of vitamin D and endorphins in the skin, therefore UV has complex and mixed effects on human health. Nonetheless, excessive exposure to UV carries profound health risks, including atrophy, pigmentary changes, wrinkling and malignancy. UV is epidemiologically and molecularly linked to the three most common types of skin cancer, basal cell carcinoma, squamous cell carcinoma and malignant melanoma, which together affect more than a million Americans annually. Genetic factors also influence risk of UV-mediated skin disease. Polymorphisms of the melanocortin 1 receptor (MC1R) gene, in particular, correlate with fairness of skin, UV sensitivity, and enhanced cancer risk. We are interested in developing UV-protective approaches based on a detailed understanding of molecular events that occur after UV exposure, focusing particularly on epidermal melanization and the role of the MC1R in genome maintenance.

Colorful DNA polymorphisms in humans

In this review article we summarize current knowledge on how variation on the DNA level influences human pigmentation including color variation of iris, hair, and skin. We review recent progress in the field of human pigmentation genetics by focusing on the genes and DNA polymorphisms discovered to be involved in determining human pigmentation traits, their association with diseases particularly skin cancers, and their power to predict human eye, hair, and skin colors with potential utilization in forensic investigations.

Genetic variants in PARP1 (rs3219090) and IRF4 (rs12203592) genes associated with melanoma susceptibility in a Spanish population

Background

Few high penetrance genes are known in Malignant Melanoma (MM), however, the involvement of low-penetrance genes such as MC1R, OCA2, ASIP, SLC45A2 and TYR has been observed. Lately, genome-wide association studies (GWAS) have been the ideal strategy to identify new common, low-penetrance susceptibility loci. In this case–control study, we try to validate in our population nine melanoma associated markers selected from published GWAS in melanoma predisposition.

Methods

We genotyped the 9 markers corresponding to 8 genes (PARP1, MX2, ATM, CCND1, NADSYN1, CASP8, IRF4 and CYP2R1) in 566 cases and 347 controls from a Spanish population using KASPar probes. Genotypes were analyzed by logistic regression and adjusted by phenotypic characteristics.

Results

We confirm the protective role in MM of the rs3219090 located on the PARP1 gene (p-value 0.027). Additionally, this SNP was also associated with eye color (p-value 0.002). A second polymorphism, rs12203592, located on the IRF4 gene was associated with protection to develop MM for the dominant model (p-value 0.037). We have also observed an association of this SNP with both lentigines (p-value 0.014) and light eye color (p-value 3.76 × 10^-4). Furthermore, we detected a novel association with rs1485993, located on the CCND1 gene, and dark eye color (p-value 4.96 × 10^-4). Finally, rs1801516, located on the ATM gene, showed a trend towards a protective role in MM similar to the one firstly described in a GWAS study.

Conclusions

To our knowledge, this is the first time that these SNPs have been associated with MM in a Spanish population. We confirmed the proposed role of rs3219090, located on the PARP1 gene, and rs12203592, located on the IRF4 gene, as protective to MM along the same lines as have previous genome-wide associated works. Finally, we have seen associations between IRF4, PARP1, and CCND1 and phenotypic characteristics, confirming previous results for the IRF4 gene and presenting novel data for the last two, suggesting that pigmentation characteristics correlated with eye color are potential mediators between PARP1 and MM protection.