Melanocytic nevi, nevus genes, and melanoma risk in a large case-control study in the United Kingdom

Review of the comparative pathological and immunohistochemical features of human and canine cutaneous melanocytic neoplasms

Melanocytic neoplasms originate from melanocytes and melanoma, the malignant form, is a common canine neoplasm and the most aggressive human skin cancer. Despite many similarities between these neoplasms in both species, only a limited number of studies have approached these entities in a comparative manner. Therefore, this review compares benign and malignant melanocytic neoplasms in dogs and humans, exclusively those arising in the haired skin, with regard to their clinicopathological, immunohistochemical and molecular aspects. Shared features include spontaneous occurrence, macroscopic features and microscopic findings when comparing human skin melanoma in the advanced/invasive stage and canine cutaneous melanoma, immunohistochemical markers and several histopathological prognostic factors. Differences include the apparent absence of active mutations in the BRAF gene in canine cutaneous melanoma and less aggressive clinical behaviour in dogs than in humans. Further studies are required to elucidate the aetiology and genetic development pathways of canine cutaneous melanocytic neoplasms. Evaluation of the applicability of histopathological prognostic parameters commonly used in humans for dogs are also needed. The similarities between the species and the recent findings regarding genetic mutations in canine cutaneous melanomas suggest the potential utility of dogs as a natural model for human melanomas that are not related to ultraviolet radiation.

The Level of Agreement between Self-Assessments and Examiner Assessments of Melanocytic Nevus Counts: Findings from an Evaluation of 4548 Double Assessments

Cutaneous melanoma (CM) is a candidate for screening programs because its prognosis is excellent when diagnosed at an early disease stage. Targeted screening of those at high risk for developing CM, a cost-effective alternative to population-wide screening, requires valid procedures to identify the high-risk group. Self-assessment of the number of nevi has been suggested as a component of such procedures, but its validity has not yet been established. We analyzed the level of agreement between self-assessments and examiner assessments of the number of melanocytic nevi in the area between the wrist and the shoulder of both arms based on 4548 study subjects in whom mutually blinded double counting of nevi was performed. Nevus counting followed the IARC protocol. Study subjects received written instructions, photographs, a mirror, and a "nevometer" to support self-assessment of nevi larger than 2 mm. Nevus counts were categorized based on the quintiles of the distribution into five levels, defining a nevus score. Cohen's weighted kappa coefficient (κ) was estimated to measure the level of agreement. In the total sample, the agreement between self-assessments and examiner assessments was moderate (weighted κ = 0.596). Self-assessed nevus counts were higher than those determined by trained examiners (mean difference: 3.33 nevi). The level of agreement was independent of sociodemographic and cutaneous factors; however, participants' eye color had a significant impact on the level of agreement. Our findings show that even with comprehensive guidance, only a moderate level of agreement between self-assessed and examiner-assessed nevus counts can be achieved. Self-assessed nevus information does not appear to be reliable enough to be used in individual risk assessment to target screening activities.

Melanocytic naevi, melanocytomas and emerging concepts

With the elucidation of the genetics of melanocytic tumours, new concepts have emerged. An important one is the identification of 'intermediate' melanocytic tumours, those with genetic progression events beyond those of melanocytic naevi but that are not fully malignant. Thus, melanocytic tumours exist on a genetic spectrum that likely corresponds to biological behaviour. There are multiple pathways to melanoma development with different initiating events and characteristic benign melanocytic neoplasms and the precise placement of tumours on these pathways remains to be established and the corresponding risks of progression quantified. In this review, I discuss the classification of melanocytic naevi based on clinical, histopathological and genetic features, as well as the concept of melanocytomas with discussion of specific recognisable subtypes.

Melanocytic nevi in sentinel lymph nodes: association with cutaneous nevi and clinical relevance in patients with cutaneous melanomas

PURPOSE

Melanocytic nevi in lymph nodes (NNs) are an important histological differential diagnosis of initial sentinel lymph node (SN) metastasis in melanoma. Our aim was to associate NN in SNs with clinicopathologic features and survival rates in 1, 250 patients with SN biopsy for melanoma.

METHODS

To compare patients with present and absent NN, we used Fisher's exact test, Mann-Whitney U test, and multivariate logistic regression models in this retrospective observational study based on a prospectively maintained institutional database.

RESULTS

NN prevalence in axillary, cervical, and groin SNs was 16.5%, 19.4%, and 9.8%, respectively. NN were observed in combination with all growth patterns of melanoma, but more frequently when the primary was histologically associated with a cutaneous nevus. We observed a decreasing NN prevalence with increasing SN metastasis diameter. Multiple logistic regression determined a significantly increased NN probability for SNs of the neck or axilla, for individuals with ≥ 50 cutaneous nevi, midline primary melanomas, and for individuals who reported non-cutaneous malignancies in their parents. Cancer in parents was also significantly more frequently reported by melanoma patients who had more than 50 cutaneous nevi. In SN-negative patients, NN indicated a tendency for slightly lower melanoma-specific survival.

CONCLUSIONS

We found a highly significant association between NN diagnosis and multiple cutaneous nevi and provided circumstantial evidence that cutaneous nevi in the drainage area of lymph nodes are particularly important. The trend toward lower melanoma-specific survival in SN-negative patients with NN suggests that careful differentiation of SN metastases is important.

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.

Body Site Distribution of Acquired Melanocytic Naevi and Associated Characteristics in the General Population of Caucasian Adults: A Scoping Review

The number of melanocytic naevi is a major risk factor for melanoma. The divergent pathway hypothesis proposes that the propensity for naevus proliferation and malignant transformation may differ by body site and exposure to ultraviolet (UV) radiation. This scoping review aimed to summarise the evidence on the number and distribution of naevi (≥ 2 mm) on the body overall and by individual anatomical sites in Caucasian adults, and to assess whether studies used the International Agency for Research on Cancer (IARC) protocol to guide naevus counting processes. Systematic searches of Embase and PubMed identified 661 potentially relevant studies, and 12 remained eligible after full-text review. Studies varied widely in their counting protocols, reporting of naevus counts overall and by body sites, and used counting personnel with differing qualifications. Only one study used the IARC protocol. Studies reported that the highest number of naevi was on the trunk in males and on the arms in females. Body sites which receive intermittent exposure to UV radiation had higher density of naevi. Larger naevi (≥ 5 mm) were detected mostly on body sites intermittently exposed to UV radiation, and smaller naevi (< 5 mm) on chronically exposed sites. Studies reported that environmental and behavioural aspects related to UV radiation exposure, as well as genetic factors, all impact body site and size distribution of naevi. This review found that to overcome limitations of the current evidence, future studies should use consistent naevus counting protocols. Skin surface imaging could improve the reliability of findings. An updated IARC protocol is required that integrates these emerging standards and technologies to guide reliable and reproducible naevus counting in the future.

Higher polygenic risk for melanoma is associated with improved survival in a high ultraviolet radiation setting

BACKGROUND

The role of germline genetic factors in determining survival from cutaneous melanoma (CM) is not well understood.

OBJECTIVE

To perform a genome-wide association study (GWAS) meta-analysis of melanoma-specific survival (MSS), and test whether a CM-susceptibility polygenic risk score (PRS) is associated with MSS.

METHODS

We conducted two Cox proportional-hazard GWAS of MSS using data from the Melanoma Institute Australia, a high ultraviolet (UV) radiation setting (MIA; 5,762 patients with melanoma; 800 melanoma deaths) and UK Biobank (UKB: 5,220 patients with melanoma; 241 melanoma deaths), and combined them in a fixed-effects meta-analysis. Significant (P < 5 × 10-8) results were investigated in the Leeds Melanoma Cohort (LMC; 1,947 patients with melanoma; 370 melanoma deaths). We also developed a CM-susceptibility PRS using a large independent GWAS meta-analysis (23,913 cases, 342,870 controls). The PRS was tested for an association with MSS in the MIA and UKB cohorts.

RESULTS

Two loci were significantly associated with MSS in the meta-analysis of MIA and UKB with lead SNPs rs41309643 (G allele frequency 1.6%, HR = 2.09, 95%CI = 1.61-2.71, P = 2.08 × 10-8) on chromosome 1, and rs75682113 (C allele frequency 1.8%, HR = 2.38, 95%CI = 1.77-3.21, P = 1.07 × 10-8) on chromosome 7. While neither SNP replicated in the LMC, rs75682113 was significantly associated in the combined discovery and replication sets. After adjusting for age at diagnosis, sex and the first ten principal components, a one standard deviation increase in the CM-susceptibility PRS was associated with improved MSS in the discovery meta-analysis (HR = 0.88, 95% CI = 0.83-0.94, P = 6.93 × 10-5; I2 = 88%). However, this was only driven by the high UV setting cohort (MIA HR = 0.84, 95% CI = 0.78-0.90).

CONCLUSION

We found two loci potentially associated with MSS. Increased genetic susceptibility to develop CM is associated with improved MSS in a high UV setting.

Defining novel causal SNPs and linked phenotypes at melanoma-associated loci

A number of genomic regions have been associated with melanoma risk through genome-wide association studies; however, the causal variants underlying the majority of these associations remain unknown. Here, we sequenced either the full locus or the functional regions including exons of 19 melanoma-associated loci in 1959 British melanoma cases and 737 controls. Variant filtering followed by Fisher's exact test analyses identified 66 variants associated with melanoma risk. Sequential conditional logistic regression identified the distinct haplotypes on which variants reside, and massively parallel reporter assays provided biological insights into how these variants influence gene function. We performed further analyses to link variants to melanoma risk phenotypes and assessed their association with melanoma-specific survival. Our analyses replicate previously known associations in the melanocortin 1 receptor (MC1R) and tyrosinase (TYR) loci, while identifying novel potentially causal variants at the MTAP/CDKN2A and CASP8 loci. These results improve our understanding of the architecture of melanoma risk and outcome.

Using the Prediction Model Risk of Bias Assessment Tool (PROBAST) to Evaluate Melanoma Prediction Studies

Simple Summary

The rising incidence of cutaneous melanoma over recent decades, combined with a general interest in cancer risk prediction, has led to a high number of published melanoma risk prediction models. The aim of our work was to assess the validity of these models in order to discuss the current state of knowledge about how to predict incident cutaneous melanoma. To assess the risk of bias, we used a standardized procedure based on PROBAST (Prediction model Risk Of Bias ASsessment Tool). Only one of the 42 studies identified was rated as having a low risk of bias. However, it was encouraging to observe a recent reduction of problematic statistical methods used in the analyses. Nevertheless, the evidence base of high-quality studies that can be used to draw conclusions on the prediction of incident cutaneous melanoma is currently much weaker than the high number of studies on this topic would suggest.

Abstract

Rising incidences of cutaneous melanoma have fueled the development of statistical models that predict individual melanoma risk. Our aim was to assess the validity of published prediction models for incident cutaneous melanoma using a standardized procedure based on PROBAST (Prediction model Risk Of Bias ASsessment Tool). We included studies that were identified by a recent systematic review and updated the literature search to ensure that our PROBAST rating included all relevant studies. Six reviewers assessed the risk of bias (ROB) for each study using the published “PROBAST Assessment Form” that consists of four domains and an overall ROB rating. We further examined a temporal effect regarding changes in overall and domain-specific ROB rating distributions. Altogether, 42 studies were assessed, of which the vast majority (n = 34; 81%) was rated as having high ROB. Only one study was judged as having low ROB. The main reasons for high ROB ratings were the use of hospital controls in case-control studies and the omission of any validation of prediction models. However, our temporal analysis results showed a significant reduction in the number of studies with high ROB for the domain “analysis”. Nevertheless, the evidence base of high-quality studies that can be used to draw conclusions on the prediction of incident cutaneous melanoma is currently much weaker than the high number of studies on this topic would suggest.

Citrus-Gene interaction and melanoma risk in the UK Biobank

High citrus consumption may increase melanoma risk; however, little is known about the biological mechanisms of this association, or whether it is modified by genetic variants. We conducted a genome-wide analysis of gene-citrus consumption interactions on melanoma risk among 1563 melanoma cases and 193 296 controls from the UK Biobank. Both the 2-degrees-of-freedom (df) joint test of genetic main effect and gene-environment (G-E) interaction and the standard 1-df G-E interaction test were performed. Three index SNPs (lowest P-value SNP among highly correlated variants [r²  > .6]) were identified from among the 365 genome-wide significant 2-df test results (rs183783391 on chromosome 3 [MITF], rs869329 on chromosome 9 [MTAP] and rs11446223 on chromosome 16 [DEF8]). Although all three were statistically significant for the 2-df test (4.25e-08, 1.98e-10 and 4.93e-13, respectively), none showed evidence of interaction according to the 1-df test (P = .73, .24 and .12, respectively). Eight nonindex, 2-df test significant SNPs on chromosome 16 were significant (P < .05) according to the 1-df test, providing evidence of citrus-gene interaction. Seven of these SNPs were mapped to AFG3L1P (rs199600347, rs111822773, rs113178244, rs3803683, rs73283867, rs78800020, rs73283871), and one SNP was mapped to GAS8 (rs74583214). We identified several genetic loci that may elucidate the association between citrus consumption and melanoma risk. Further studies are needed to confirm these findings.

Association of Melanoma-Risk Variants with Primary Melanoma Tumor Prognostic Characteristics and Melanoma-Specific Survival in the GEM Study

Genome-wide association studies (GWAS) and candidate pathway studies have identified low-penetrant genetic variants associated with cutaneous melanoma. We investigated the association of melanoma-risk variants with primary melanoma tumor prognostic characteristics and melanoma-specific survival. The Genes, Environment, and Melanoma Study enrolled 3285 European origin participants with incident invasive primary melanoma. For each of 47 melanoma-risk single nucleotide polymorphisms (SNPs), we used linear and logistic regression modeling to estimate, respectively, the per allele mean changes in log of Breslow thickness and odds ratios for presence of ulceration, mitoses, and tumor-infiltrating lymphocytes (TILs). We also used Cox proportional hazards regression modeling to estimate the per allele hazard ratios for melanoma-specific survival. Passing the false discovery threshold (p = 0.0026) were associations of IRF4 rs12203592 and CCND1 rs1485993 with log of Breslow thickness, and association of TERT rs2242652 with presence of mitoses. IRF4 rs12203592 also had nominal associations (p < 0.05) with presence of mitoses and melanoma-specific survival, as well as a borderline association (p = 0.07) with ulceration. CCND1 rs1485993 also had a borderline association with presence of mitoses (p = 0.06). MX2 rs45430 had nominal associations with log of Breslow thickness, presence of mitoses, and melanoma-specific survival. Our study indicates that further research investigating the associations of these genetic variants with underlying biologic pathways related to tumor progression is warranted.

The role of MC1R gene variants and phenotypical features in predicting high nevus count

Variants in the Melanocortin 1 Receptor (MC1R) gene have been associated with an increased risk of melanoma, but the role in nevus count is unclear. We investigated if specific MC1R gene variants or the number of MC1R gene variants and phenotypical features were associated with nevus count. A total of 494 participants of the 'Leiden skin cancer study' were included and the MC1R gene coding sequence was analysed by single-strand conformation polymorphism analysis followed by sequencing of unknown variants. The association between MC1R gene variants and nevus count and the association between age, gender and phenotypical features and nevus count were studied using the Chi-square test. Study of nine frequently occurring MC1R gene variants in participants without skin cancer (n = 203) showed that the 'r' Val60Leu variant was significantly associated with high nevus count (>50 nevi) (P = 0.017). This association was very strong among women (P < 0.001), but not present among men. Having one or two MC1R variants in general did not show a significant difference in the nevus count. Hair colour, skin type, eye colour and age were not significantly associated with nevus count, whereas gender showed a significant association (P = 0.008), with the highest nevus counts in female. The Val60Leu variant of the MC1R gene could be a promising candidate as an independent predictor of high nevus count, particularly in women. This information about the genetic makeup could promote personalized follow-up strategies and might help to prevent skin cancer in the future.

The Interplay between Nevi and Melanoma Predisposition Unravels Nevi-Related and Nevi-Resistant Familial Melanoma

Genetic susceptibility to nevi may affect the risk of developing melanoma, since common and atypical nevi are the main host risk factors implicated in the development of cutaneous melanoma. Recent genome-wide studies defined a melanoma polygenic risk score based on variants in genes involved in different pathways, including nevogenesis. Moreover, a predisposition to nevi is a hereditary trait that may account for melanoma clustering in some families characterized by cases with a high nevi density. On the other hand, familial melanoma aggregation may be due to a Mendelian inheritance of high/moderate-penetrance pathogenic variants affecting melanoma risk, regardless of the nevus count. Based on current knowledge, this review analyzes the complex interplay between nevi and melanoma predisposition in a familial context. We review familial melanoma, starting from Whiteman's divergent pathway model to overall melanoma development, distinguishing between nevi-related (cases with a high nevus count and a high polygenic risk score) and nevi-resistant (high/moderate-penetrance variant-carrier cases) familial melanoma. This distinction could better direct future research on genetic factors useful to identify high-risk subjects.

Cutaneous Melanoma Classification: The Importance of High-Throughput Genomic Technologies

Cutaneous melanoma is an aggressive tumor responsible for 90% of mortality related to skin cancer. In the recent years, the discovery of driving mutations in melanoma has led to better treatment approaches. The last decade has seen a genomic revolution in the field of cancer. Such genomic revolution has led to the production of an unprecedented mole of data. High-throughput genomic technologies have facilitated the genomic, transcriptomic and epigenomic profiling of several cancers, including melanoma. Nevertheless, there are a number of newer genomic technologies that have not yet been employed in large studies. In this article we describe the current classification of cutaneous melanoma, we review the current knowledge of the main genetic alterations of cutaneous melanoma and their related impact on targeted therapies, and we describe the most recent high-throughput genomic technologies, highlighting their advantages and disadvantages. We hope that the current review will also help scientists to identify the most suitable technology to address melanoma-related relevant questions. The translation of this knowledge and all actual advancements into the clinical practice will be helpful in better defining the different molecular subsets of melanoma patients and provide new tools to address relevant questions on disease management. Genomic technologies might indeed allow to better predict the biological - and, subsequently, clinical - behavior for each subset of melanoma patients as well as to even identify all molecular changes in tumor cell populations during disease evolution toward a real achievement of a personalized medicine.

Acral lentiginous melanoma: Basic facts, biological characteristics and research perspectives of an understudied disease

Acral lentiginous melanoma is a histological subtype of cutaneous melanoma that occurs in the glabrous skin of the palms, soles and the nail unit. Although in some countries, particularly in Latin America, Africa and Asia, it represents the most frequently diagnosed subtype of the disease, it only represents a small proportion of melanoma cases in European‐descent populations, which is partially why it has not been studied to the same extent as other forms of melanoma. As a result, its unique genomic drivers remain comparatively poorly explored, as well as its causes, with current evidence supporting a UV‐independent path to tumorigenesis. In this review, we discuss current knowledge of the aetiology and diagnostic criteria of acral lentiginous melanoma, as well as its epidemiological and histopathological characteristics. We also describe what is known about the genomic landscape of this disease and review the available biological models to explore potential therapeutic targets.

Development and external validation study of a melanoma risk prediction model incorporating clinically assessed naevi and solar lentigines

BACKGROUND

Melanoma risk prediction models could be useful for matching preventive interventions to patients' risk.

OBJECTIVES

To develop and validate a model for incident first-primary cutaneous melanoma using clinically assessed risk factors.

METHODS

We used unconditional logistic regression with backward selection from the Australian Melanoma Family Study (461 cases and 329 controls) in which age, sex and city of recruitment were kept in each step, and we externally validated it using the Leeds Melanoma Case-Control Study (960 cases and 513 controls). Candidate predictors included clinically assessed whole-body naevi and solar lentigines, and self-assessed pigmentation phenotype, sun exposure, family history and history of keratinocyte cancer. We evaluated the predictive strength and discrimination of the model risk factors using odds per age- and sex-adjusted SD (OPERA) and the area under curve (AUC), and calibration using the Hosmer-Lemeshow test.

RESULTS

The final model included the number of naevi ≥ 2 mm in diameter on the whole body, solar lentigines on the upper back (a six-level scale), hair colour at age 18 years and personal history of keratinocyte cancer. Naevi was the strongest risk factor; the OPERA was 3·51 [95% confidence interval (CI) 2·71-4·54] in the Australian study and 2·56 (95% CI 2·23-2·95) in the Leeds study. The AUC was 0·79 (95% CI 0·76-0·83) in the Australian study and 0·73 (95% CI 0·70-0·75) in the Leeds study. The Hosmer-Lemeshow test P-value was 0·30 in the Australian study and < 0·001 in the Leeds study.

CONCLUSIONS

This model had good discrimination and could be used by clinicians to stratify patients by melanoma risk for the targeting of preventive interventions. What's already known about this topic? Melanoma risk prediction models may be useful in prevention by tailoring interventions to personalized risk levels. For reasons of feasibility, time and cost many melanoma prediction models use self-assessed risk factors. However, individuals tend to underestimate their naevus numbers. What does this study add? We present a melanoma risk prediction model, which includes clinically-assessed whole-body naevi and solar lentigines, and self-assessed risk factors including pigmentation phenotype and history of keratinocyte cancer. This model performs well on discrimination, the model's ability to distinguish between individuals with and without melanoma, and may assist clinicians to stratify patients by melanoma risk for targeted preventive interventions.

Dissimilar Appearances Are Deceptive-Common microRNAs and Therapeutic Strategies in Liver Cancer and Melanoma

In this review, we summarize the current knowledge on miRNAs as therapeutic targets in two cancer types that were frequently described to be driven by miRNAs—melanoma and hepatocellular carcinoma (HCC). By focusing on common microRNAs and associated pathways in these—at first sight—dissimilar cancer types, we aim at revealing similar molecular mechanisms that are evolved in microRNA-biology to drive cancer progression. Thereby, we also want to outlay potential novel therapeutic strategies. After providing a brief introduction to general miRNA biology and basic information about HCC and melanoma, this review depicts prominent examples of potent oncomiRs and tumor-suppressor miRNAs, which have been proven to drive diverse cancer types including melanoma and HCC. To develop and apply miRNA-based therapeutics for cancer treatment in the future, it is essential to understand how miRNA dysregulation evolves during malignant transformation. Therefore, we highlight important aspects such as genetic alterations, miRNA editing and transcriptional regulation based on concrete examples. Furthermore, we expand our illustration by focusing on miRNA-associated proteins as well as other regulators of miRNAs which could also provide therapeutic targets. Finally, design and delivery strategies of miRNA-associated therapeutic agents as well as potential drawbacks are discussed to address the question of how miRNAs might contribute to cancer therapy in the future.

New and evolving concepts of melanocytic nevi and melanocytomas

In daily clinical practice melanocytic nevi are commonly encountered. Traditionally, both benign and malignant melanocytic tumors have been sub-classified by their histopathologic characteristics with differing criteria for malignancy applied to each group. Recently, many of the mutations that initiate nevus formation have been identified and specific sets of mutations are found in different subtypes of nevi. Whereas a single mutation appears sufficient to initiate a nevus, but is not enough to result in melanoma, specific combinations of mutations have been identified in some melanocytic tumors that are regarded to be of low biologic potential. The term "melanocytoma" has recently been proposed by the World Health Organization to describe those tumors that demonstrate genetic progression beyond the single mutations that are found in nevi but are not frankly malignant. Melanocytomas occupy intermediate genetic stages between nevus and melanoma and likely have an increased risk of malignant transformation as compared to nevi. This review provides an update on the broad spectrum of melanocytic nevi and melanocytomas and outlines their key histopathologic and genetic features.

Body site-specific genetic effects influence naevus count distribution in women

Body site is highly relevant for melanoma: it affects prognosis and varies according to the patient's sex. The distribution of naevi, a major risk factor for melanoma, at different body sites also varies according to sex in childhood. Using naevus counts at different body sites in 492 unrelated adults from both sexes, we observed that women have an increased number of naevi on the lower limbs compared to men (p = 8.5 × 10^-5 ), showing that a high naevus count on this site persists from childhood throughout life. Then, using data from 3,232 twins, we observed, in women, the lowest naevus count heritability on the trunk (26%), and the highest on the lower limbs (69%). Finally, we showed that, in 2,864 women, six genomic loci previously associated with both naevus count and melanoma risk (IRF4, DOCK8, MTAP, 9q31.2, KITLG and PLA2G6) have an effect on naevus count that is body site-specific, but whose effect sizes are predominantly stronger on the lower limbs. Sex-specific genetic influence on naevus count at different sites may explain differences in site-specific melanoma incidence as well as prognosis between sexes.

Cutaneous nevi and risk of melanoma death in women and men: A prospective study

BACKGROUND

It was unclear whether an increased number of common nevi (moles) predicts melanoma death.

OBJECTIVE

We prospectively examined the association between number of common nevi and risk of melanoma death.

METHODS

Our study used data from the Nurses' Health Study (n = 77,288 women) and Health Professionals Follow-up Study (n = 32,455 men). In 1986, participants were asked about the number of moles they had with a ≥3-mm diameter on the upper extremity, and we stratified their answers into 3 categories (none, 1-2, or ≥3) on the basis of data distribution.

RESULTS

During follow-up (1986-2012), 2452 melanoma cases were pathologically confirmed; among these, we identified 196 deaths due to melanoma. Increased number of nevi was associated with melanoma death; the hazard ratio (HR) for ≥3 nevi compared with no nevi was 2.49 (95% confidence interval [CI] 1.50-4.12) for women and 3.97 (95% CI 2.54-6.22) for men. Among melanoma cases, increased number of nevi was associated with melanoma death in men (≥3 nevi, HR 1.89, 95% CI 1.17-3.05) but not in women. Similarly, the number of nevi was positively associated with Breslow thickness in men only (Ptrend = .01).

LIMITATIONS

This is an epidemiologic study without examination into mechanisms.

CONCLUSION

Increased number of cutaneous nevi was significantly associated with melanoma death. High nevus count might serve as an independent prognostic factor to predict the risk of melanoma death particularly among male melanoma patients.

Risk Factors of Subsequent Primary Melanomas in Austria

Importance

Information on risk factors of subsequent melanomas would be helpful to identify patients at risk after the diagnosis of their first melanomas.

Objective

To determine risk factors of subsequent melanomas.

Design, Setting, and Participants

In this retrospective case-control study, 1648 participants with histologically verified cutaneous melanoma diagnosed from January 1, 1968, though March 16, 2015, were recruited from a tertiary referral center as part of the Molecular Markers of Melanoma study. CDKN2A was sequenced in 514 and MC1R in 953 participants. Data were analyzed from March 7, 2008, through March 25, 2015.

Main Outcomes and Measures

Phenotypic traits and internal and external risk factors for the development of a second, third, or fourth melanoma.

Results

In total, 1648 patients (53.6% men; mean [SD] age, 54 [15] years) were enrolled, including 1349 with single and 299 with multiple primary melanoma. Mean (SD) age at recruitment was 57 (15) years for the single-melanoma and 62 (14) years for the multiple-melanoma groups. From the internal risk factors, family history (odds ratio [OR], 1.76; 95% CI, 1.22-2.55; P = .006), CDKN2A high-risk mutations (OR, 4.03; 95% CI, 1.28-12.70; P = .02), and high numbers of nevi as a phenotypic risk factor (ORs, 2.23 [95% CI, 1.56-3.28, P < .001] for 20-30 smaller nevi and 2.56 [95% CI, 1.50-4.36; P = .003] for 20-30 larger nevi) were significantly associated with the risk of developing a subsequent primary melanoma using multivariate logistic regression analysis. Nonmelanoma skin cancer (OR, 2.57; 95% CI, 1.84-3.58; P < .001) and signs of actinic skin damage, particularly on the back (ORs, 1.91 [95% CI, 1.12-3.25; P = .04] for freckling and 1.92 [95% CI, 1.29-3.08; P = .007] for solar lentigines), additionally increased risk of a subsequent melanoma. All those factors were also associated with an earlier development of the second melanoma. Patients with 3 melanomas developed their second melanoma earlier than patients with only 2 melanomas (mean [SD] age, 55 [15] years for those with 2 primary melanomas; 52 [15] years for those with 3 primary melanomas). Time spent outdoors, solarium use, outdoor occupation, and hair color had no significant associations in these models.

Conclusions and Relevance

According to the results of this study, internal factors (family history and genetic variants), number of nevi, and actinic damage on the back are more relevant for the development of subsequent melanomas than skin phototype or hair color. Patients with many nevi were younger at the time of the diagnosis of their first melanoma. This finding could help to identify persons at increased risk of developing multiple primary melanomas.

The Melanocortin 1 receptor and its influence on naevi and melanoma in dark-skinned phenotypes

It is well appreciated that melanocortin 1 receptor variants can produce a fair skinned and red-haired phenotype that has a strong association with increased melanoma risk. These patients are easily recognised and given appropriate attention. What may not be appreciated is that darker-skinned individuals may also carry melanocortin 1 receptor variant alleles and that they can also be at increased risk of melanoma. Considering that melanocortin 1 receptor is crucial for melanocyte proliferation, regulation and differentiation do the naevi of these darker-skinned individuals have specific features that help identify them as carrying one of these melanocortin 1 receptor variants and do melanomas that develop in dark-skinned melanocortin 1 receptor variant carriers have particular characteristics?

Novel pleiotropic risk loci for melanoma and nevus density implicate multiple biological pathways

The total number of acquired melanocytic nevi on the skin is strongly correlated with melanoma risk. Here we report a meta-analysis of 11 nevus GWAS from Australia, Netherlands, UK, and USA comprising 52,506 individuals. We confirm known loci including MTAP, PLA2G6, and IRF4, and detect novel SNPs in KITLG and a region of 9q32. In a bivariate analysis combining the nevus results with a recent melanoma GWAS meta-analysis (12,874 cases, 23,203 controls), SNPs near GPRC5A, CYP1B1, PPARGC1B, HDAC4, FAM208B, DOCK8, and SYNE2 reached global significance, and other loci, including MIR146A and OBFC1, reached a suggestive level. Overall, we conclude that most nevus genes affect melanoma risk (KITLG an exception), while many melanoma risk loci do not alter nevus count. For example, variants in TERC and OBFC1 affect both traits, but other telomere length maintenance genes seem to affect melanoma risk only. Our findings implicate multiple pathways in nevogenesis.

Genetic variants associated with skin photosensitivity in a southern European population from Spain

BACKGROUND/PURPOSE

Recent GWAS studies, mostly performed in populations of North European origin, have identified the genetic loci associated with pigmentation, sun sensitivity, freckling and skin cancer susceptibility. Here, we aimed at addressing the genetic determinants of sunlight sensitivity in Spain, a southern European population.

METHODS

Nine SNPs located in 8 pigmentation-related genes (IRF4, TYR, ASP, HERC2, OCA2, BNC2, SLC24A4 and SLC45A2) were genotyped in 456 Spaniards. Additionally, the complete sequence of the MC1R gene was obtained, testing each nonsynonymous mutation supported by the classification as R or r alleles. A standardised questionnaire was used to collect demographic characteristics, pigmentation and sun sensitivity traits, as well as sun exposure habits.

RESULTS

MC1R R alleles and IRF4 rs12203592 were significantly associated with sunlight sensitivity at the Bonferroni-corrected level (P-value < 4.54 × 10^-3 ). Genetic variants in SLC45A2 (rs16891982) and HERC2 (rs12913832) were also found to be significantly associated with skin photosensitivity in our Spanish sample. Interaction analysis using the MDR method revealed epistatic effects when these four variants were considered together.

CONCLUSION

MC1R, IRF4, HERC2 and SLC45A2 play a significant role in skin sensitivity to sunlight in the Spanish population. Moreover, interaction among these four loci seems to modulate the ability of the skin to respond to UV radiation.

Factors Related to Nevus-Associated Cutaneous Melanoma: A Case-Case Study

A proportion of cutaneous melanomas display neval remnants on histologic examination. Converging lines of epidemiologic and molecular evidence suggest that melanomas arising from nevus precursors differ from melanomas arising de novo. In a large, population-based study comprising 636 cutaneous melanomas subjected to dermatopathology review, we explored the molecular, host, and environmental factors associated with the presence of neval remnants. We found that nevus-associated melanomas were significantly associated with younger age at presentation, non-brown eye color, trunk site, thickness of less than 0.5 mm, and BRAF^V600E mutation. Compared with patients with de novo melanomas, those with nevus-associated tumors were more likely to self-report many moles on their skin as a teenager (odds ratio = 1.94, 95% confidence interval = 1.01-3.72) but less likely to report many facial freckles (odds ratio = 0.49, 95% confidence interval = 0.25-0.96). They also had high total nevus counts (odds ratio = 2.18, 95% confidence interval = 1.26-3.78). On histologic examination, nevus-associated melanomas exhibited less dermal elastosis in adjacent skin compared with de novo melanomas (odds ratio = 0.55, 95% confidence interval = 0.30-1.01). These epidemiologic data accord with the emerging molecular paradigm that nevus-associated melanomas arise through a distinct sequence of causal events that differ from those leading to other cutaneous melanomas.

A Randomized Trial of an Advanced Sun Safety Intervention for Vacationers at 41 North American Resorts

Taking vacations in sunny locations is associated with the development of skin cancer. This study tested a multi-component sun protection intervention based on diffusion of innovations theory and transportation theory designed to increase vacationers' comprehensive sun protection, i.e., use of clothing, hats, and shade, and use, pre-application, and reapplication of sunscreen. The trial enrolled 41 warm weather resorts in North America in a pair-matched group randomized pretest-posttest design and assessed samples of adult vacationers at resort outdoor recreation venues regarding sun protection at pretest (n = 3,531) and posttest (n = 3,226). While results showed no overall effect of the intervention on comprehensive sun protection across venues, the intervention produced statistically significant improvements in sun protection at waterside venues (pools and beaches). The intervention's overall effects may have been impeded by a lack of uniformly robust implementation, low interest in skin cancer prevention by guests, or shortcomings of the theories used to create prevention messages. The intervention may have worked best with guests in the highest-risk recreation venue, i.e., waterside recreation where they exposed the most skin. Alternative approaches that alter resort organizations, such as through changes in policy, environmental features, or occupational efforts might be more effective than targeting vacationers with behavior-change messages.

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.

Effect of an intervention on observed sun protection by vacationers in a randomized controlled trial at North American resorts

During vacations, many individuals receive high-risk sun exposure that is associated with skin cancer. Vacationers in outdoor recreation venues (pretest n=4347; posttest n=3986) at warm-weather destination resorts in North America (n=41) were enrolled in a pair-matched, group-randomized pretest-posttest controlled quasi-experimental design in 2012-14. Print, audiovisual, and online messages based on Transportation Theory and Diffusion of Innovation Theory and promoting advanced sun protection (e.g., use of clothing, hats, shade and pre-application/reapplication of sunscreen and reliable cues to high UV) were delivered through resort channels. Vacationers' sun protection practices observed by trained research staff (i.e., body coverage and shade use analyzed individually and in combined scores) did not differ by experimental condition (p>0.05) or intervention implementation (p>0.05). However, recreation venue moderated intervention impact. The intervention improved sun protection at waterside recreation venues (z-score composite: intervention pre=-22.74, post=-15.77; control pre=-27.24, post=-23.24) but not non-waterside venues (z-score composite: intervention pre=20.43, post=20.53; control pre=22.94, post=18.03, p<0.01). An additional analysis showed that resorts with greater program implementation showed more improvements in sun protection by vacationers at waterside (z=score composite: high implementation pre=-25.45, post=-14.05; low implementation pre=-24.70, post=-21.40) compared to non-waterside (z-score composite: high implementation pre=14.51, post=19.98; low implementation pre=24.03, post=18.98, p<0.01) recreation venues. The intervention appeared effective with the vacationers in recreation venues with the highest-risk for sun exposure, waterside venues. However, it was not effective throughout all the resort venues, possibly because of the sun-seeking desires of vacationers, information overload at the resorts, and constraints on clothing styles and sun protection by recreation activity.

Meta-analysis of the Correlation Between Interleukin-6 Promoter Polymorphism -174G/C and Interferon Regulatory Factor 4 rs12203592 Polymorphism With Skin Cancer Susceptibility

Inflammation is a process whereby the immune system responds to a disease or injury. Chronic inflammation, however, has been linked to several types of cancers such as skin cancer. Molecular epidemiological studies were carried out in recent years evaluating interferon regulatory factor 4 (IRF4) rs12203592 and interleukin-6 (IL-6) gene -174G/C polymorphism associated with skin cancer risk for different groups of people. However, the results are still conflicting, not conclusive. We performed a meta-analysis to investigate the association between cancer susceptibility and IL-6 -174G/C (1130 cases and 1260 controls from 7 studies) and IRF4 rs12203592 polymorphisms (3879 cases and 6759 controls from 9 studies) in different inheritance models. We assess the strength of association of odds ratio (ORs), 95% confidence interval (CI). Overall, significantly elevated skin cancer risk was found when all studies were pooled into the meta-analysis of IL-6 -174G/C (For GC vs. GG: OR = 1.28, 95% CI, 1.06-1.54, I = 0, Pheterogeneity = 0.816; for CC/GC vs. GG: OR = 1.26, 95% CI, 1.05-1.50, I = 0, Pheterogeneity = 0.618). However, for IRF4 rs12203592 polymorphism, significantly increased risk of skin cancer was observed in TT versus CC (OR = 1.99, 95% CI, 1.30-3.07, I = 76.7%, Pheterogeneity < 0.001) and in recessive model (OR = 1.91, 95% CI, 1.31-2.77, I = 69.9%, Pheterogeneity < 0.001). This meta-analysis indicates that the IL-6 gene -174G/C and IRF4 rs12203592 polymorphisms may be associated with an increased skin cancer risk.

Five-point checklist for skin cancer detection in primary care

BACKGROUND

Skin cancer screening interventions often relay on the involvement of general practitioners (GPs). Many interventions up to now have been directed to training approaches focusing on the clinical features of skin malignancies to increase GPs skill in skin cancer recognition.

METHODS

Based on the available current knowledge about skin cancer epidemiology and risk factors, we built up a 5-point checklist to help GPs in triaging patients to be referred to a dermatologist.

RESULTS

Five-point check-list: 1) visible sun damaged skin on exposed areas (red and brown to black macules and crusts on visible skin); 2) more than 20 nevi on the arms; 3) one or more ABCD positive lesions (flat, large and asymmetric macules); 4) one or more EFG positive lesions (elevated, firm and growing skin lesions); 5) a pigmented lesion larger than 1.5 cm in diameter.

CONCLUSIONS

Our aim was to provide a short list of practical rules, easy to adopt into a routine practice, in order to achieve a more effective triage of patients requiring a dermatology consultation for skin cancer examination. The novelty of the proposed method relies on the approach. The proposed method does not require the GP to diagnose skin cancer. The aim is to involve GPs in the selection of patients to be referred to the specialist, in order to reduce the waiting time while avoiding the risk to leave cancers untreated.

A population-based analysis of germline BAP1 mutations in melanoma

Germline mutation of the BRCA1 associated protein-1 (BAP1) gene has been linked to uveal melanoma, mesothelioma, meningioma, renal cell carcinoma and basal cell carcinoma. Germline variants have also been found in familial cutaneous melanoma pedigrees, but their contribution to sporadic melanoma has not been fully assessed. We sequenced BAP1 in 1,977 melanoma cases and 754 controls and used deubiquitinase assays, a pedigree analysis, and a histopathological review to assess the consequences of the mutations found. Sequencing revealed 30 BAP1 variants in total, of which 27 were rare (ExAc allele frequency <0.002). Of the 27 rare variants, 22 were present in cases (18 missense, one splice acceptor, one frameshift and two near splice regions) and five in controls (all missense). A missense change (S98R) in a case that completely abolished BAP1 deubiquitinase activity was identified. Analysis of cancers in the pedigree of the proband carrying the S98R variant and in two other pedigrees carrying clear loss-of-function alleles showed the presence of BAP1-associated cancers such as renal cell carcinoma, mesothelioma and meningioma, but not uveal melanoma. Two of these three probands carrying BAP1 loss-of-function variants also had melanomas with histopathological features suggestive of a germline BAP1 mutation. The remaining cases with germline mutations, which were predominantly missense mutations, were associated with less typical pedigrees and tumours lacking a characteristic BAP1-associated histopathological appearances, but may still represent less penetrant variants. Germline BAP1 alleles defined as loss-of-function or predicted to be deleterious/damaging are rare in cutaneous melanoma.

Melanocytic Nevi and the Genetic and Epigenetic Control of Oncogene-Induced Senescence

Melanocytic nevi represent benign clonal proliferations of the melanocytes in the skin that usually remain stable in size and behavior or disappear during life. Infrequently, melanocytic nevi undergo malignant transformation to melanoma. Understanding molecular and cellular mechanisms underlying oncogene-induced senescence should help identify pathways underlying melanoma development, leading to the development of new strategies for melanoma prevention and early detection.

Characterization of the Methylthioadenosine Phosphorylase Polymorphism rs7023954 - Incidence and Effects on Enzymatic Function in Malignant Melanoma

Deficiency of methylthioadenosine phosphorylase (MTAP) supports melanoma development and progression through accumulation of its substrate 5’-methylthioadenosine (MTA), which leads amongst others to a constitutive inhibition of protein arginine methyltransferases (PRMTs) and activation of the transcription factor AP-1 via the receptor ADORA2B. Genetic association studies have also suggested that genetic polymorphism in MTAP may modulate the risk of melanoma. Here, we investigated the only globally common non-synonymous single nucleotide polymorphism (SNP) reported to date for MTAP. The SNP rs7023954 is located in exon 3 (c.166G>A), and leads to the conservative substitution of one branched-chain amino acid residue (valine) for another (isoleucine) at position 56 (p.Val56Ile). Whereas genotype frequencies in normal and primary melanoma tissues or cell lines were in Hardy-Weinberg equilibrium based on cDNA amplicon sequencing, a marked (P = 0.00019) deviation was observed in metastatic melanoma tissues and cell lines due to a deficit of heterozygotes. Enzyme assays conducted on the co-dominantly expressed alleles revealed no difference in the conversion rate of MTA to adenine and 5-methylthioribose-1-phosphate, indicating that this known enzymatic activity does not modulate the tumor suppressive function of MTAP.

Association of nevus count with prevention attitudes and behaviors before melanoma diagnosis

Although melanoma risk factors are commonly known to healthcare professionals, the extent to which the at-risk public is either aware of these factors or perceives their risk accordingly has rarely been studied. We sought to investigate whether the presence of known melanoma risk factors, such as high total nevus and atypical nevus counts, was associated with increased prevention attitudes and behaviors, such as skin self-examinations and physician skin examinations. This was a retrospective study of 566 individuals recently diagnosed with melanoma in two large academic centers. Most prevention attitudes and behaviors did not vary on the basis of total nevi or atypical nevi counts. However, younger patients (<60 years) with many total nevi (>50) were more likely than those with fewer nevi (<20) to believe that they were at-risk for melanoma (42 vs. 23%; P<0.05), and more likely to state that they had been instructed on the signs of melanoma (36 vs. 21%; P<0.05). Patient and health provider recognition of the impact of nevus count on melanoma risk presents a unique and mostly untapped opportunity for earlier detection.

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.

The CDKN2A/p16(INK) (4a) 5'UTR sequence and translational regulation: impact of novel variants predisposing to melanoma

Many variants of uncertain functional significance in cancer susceptibility genes lie in regulatory regions, and clarifying their association with disease risk poses significant challenges. We studied 17 germline variants (nine of which were novel) in the CDKN2A 5'UTR with independent approaches, which included mono and bicistronic reporter assays, Western blot of endogenous protein, and allelic representation after polysomal profiling to investigate their impact on CDKN2A mRNA translation regulation. Two of the novel variants (c.-27del23, c.-93-91delAGG) were classified as causal mutations (score ≥3), along with the c.-21C>T, c.-34G>T, and c.-56G>T, which had already been studied by a subset of assays. The novel c.-42T>A as well as the previously described c.-67G>C were classified as potential mutations (score 1 or 2). The remaining variants (c.-14C>T, c.-20A>G, c.-25C>T+c.-180G>A, c.-30G>A, c.-40C>T, c.-45G>A, c.-59C>G, c.-87T>A, c.-252A>T) were classified as neutral (score 0). In conclusion, we found evidence that nearly half of the variants found in this region had a negative impact on CDKN2A mRNA translation, supporting the hypothesis that 5'UTR can act as a cellular Internal Ribosome Entry Site (IRES) to modulate p16(INK) (4a) translation.

Association of Interferon Regulatory Factor-4 Polymorphism rs12203592 With Divergent Melanoma Pathways

BACKGROUND

Solar elastosis and neval remnants are histologic markers characteristic of divergent melanoma pathways linked to differences in age at onset, host phenotype, and sun exposure. However, the association between these pathway markers and newly identified low-penetrance melanoma susceptibility loci remains unknown.

METHODS

In the Genes, Environment and Melanoma (GEM) Study, 2103 Caucasian participants had first primary melanomas that underwent centralized pathology review. For 47 single-nucleotide polymorphisms (SNPs) previously identified as low-penetrant melanoma risk variants, we used multinomial logistic regression to compare melanoma with solar elastosis and melanoma with neval remnants simultaneously to melanoma with neither of these markers, excluding melanomas with both markers. All statistical tests were two-sided.

RESULTS

IRF4 rs12203592 was the only SNP to pass the false discovery threshold in baseline models adjusted for age, sex, and study center. rs12203592*T was associated positively with melanoma with solar elastosis (odds ratio [OR] = 1.47, 95% confidence interval [CI] = 1.18 to 1.82) and inversely with melanoma with neval remnants (OR = 0.65, 95% CI = 0.48 to 0.87) compared with melanoma with neither marker (P global = 3.78 x 10(-08)). Adjusting for phenotypic characteristics and total sun exposure hours did not materially affect rs12203592's associations. Distinct early- and late-onset age distributions were observed in patients with IRF4 rs12203592 [CC] and [TT] genotypes, respectively.

CONCLUSIONS

Our findings suggest a role of IRF4 rs12203592 in pathway-specific risk for melanoma development. We hypothesize that IRF4 rs12203592 could underlie in part the bimodal age distribution reported for melanoma and linked to the divergent pathways.

Germline TERT promoter mutations are rare in familial melanoma

Germline CDKN2A mutations occur in 40 % of 3-or-more case melanoma families while mutations of CDK4, BAP1, and genes involved in telomere function (ACD, TERF2IP, POT1), have also been implicated in melanomagenesis. Mutation of the promoter of the telomerase reverse transcriptase (TERT) gene (c.-57 T>G variant) has been reported in one family. We tested for the TERT promoter variant in 675 multicase families wild-type for the known high penetrance familial melanoma genes, 1863 UK population-based melanoma cases and 529 controls. Germline lymphocyte telomere length was estimated in carriers. The c.-57 T>G TERT promoter variant was identified in one 7-case family with multiple primaries and early age of onset (earliest, 15 years) but not among population cases or controls. One family member had multiple primary melanomas, basal cell carcinomas and a bladder tumour. The blood leukocyte telomere length of a carrier was similar to wild-type cases. We provide evidence confirming that a rare promoter variant of TERT (c.-57 T>G) is associated with high penetrance, early onset melanoma and potentially other cancers, and explains <1 % of UK melanoma multicase families. The identification of POT1 and TERT germline mutations highlights the importance of telomere integrity in melanoma biology.

Genetics of melanoma progression: the rise and fall of cell senescence

There are many links between cell senescence and the genetics of melanoma, meaning both familial susceptibility and somatic-genetic changes in sporadic melanoma. For example, CDKN2A, the best-known melanoma susceptibility gene, encodes two effectors of cell senescence, while other familial melanoma genes are related to telomeres and their maintenance. This article aimed to analyze our current knowledge of the genetic or epigenetic driver changes necessary to generate a cutaneous metastatic melanoma, the commonest order in which these occur, and the relation of these changes to the biology and pathology of melanoma progression. Emphasis is laid on the role of cell senescence and the escape from senescence leading to cellular immortality, the ability to divide indefinitely.

Genome-wide meta-analysis identifies five new susceptibility loci for cutaneous malignant melanoma

Thirteen common susceptibility loci have been reproducibly associated with cutaneous malignant melanoma (CMM). We report the results of an international 2-stage meta-analysis of CMM genome-wide association studies (GWAS). This meta-analysis combines 11 GWAS (5 previously unpublished) and a further three stage 2 data sets, totaling 15,990 CMM cases and 26,409 controls. Five loci not previously associated with CMM risk reached genome-wide significance (P < 5 × 10(-8)), as did 2 previously reported but unreplicated loci and all 13 established loci. Newly associated SNPs fall within putative melanocyte regulatory elements, and bioinformatic and expression quantitative trait locus (eQTL) data highlight candidate genes in the associated regions, including one involved in telomere biology.

Interactions between ultraviolet light and MC1R and OCA2 variants are determinants of childhood nevus and freckle phenotypes

BACKGROUND

Melanocytic nevi (moles) and freckles are well known biomarkers of melanoma risk, and they are influenced by similar UV light exposures and genetic susceptibilities to those that increase melanoma risk. Nevertheless, the selective interactions between UV exposures and nevus and freckling genes remain largely undescribed.

METHODS

We conducted a longitudinal study from ages 6 through 10 years in 477 Colorado children who had annual information collected for sun exposure, sun protection behaviors, and full body skin exams. MC1R and HERC2/OCA2 rs12913832 were genotyped and linear mixed models were used to identify main and interaction effects.

RESULTS

All measures of sun exposure (chronic, sunburns, and waterside vacations) contributed to total nevus counts, and cumulative chronic exposure acted as the major driver of nevus development. Waterside vacations strongly increased total nevus counts in children with rs12913832 blue eye color alleles and facial freckling scores in those with MC1R red hair color variants. Sunburns increased the numbers of larger nevi (≥2 mm) in subjects with certain MC1R and rs12913832 genotypes.

CONCLUSIONS

Complex interactions between different UV exposure profiles and genotype combinations determine nevus numbers and size, and the degree of facial freckling.

IMPACT

Our findings emphasize the importance of implementing sun-protective behavior in childhood regardless of genetic make-up, although children with particular genetic variants may benefit from specifically targeted preventive measures to counteract their inherent risk of melanoma. Moreover, we demonstrate, for the first time, that longitudinal studies are a highly powered tool to uncover new gene-environment interactions that increase cancer risk.

Independent replication of a melanoma subtype gene signature and evaluation of its prognostic value and biological correlates in a population cohort

Development and validation of robust molecular biomarkers has so far been limited in melanoma research. In this paper we used a large population-based cohort to replicate two published gene signatures for melanoma classification. We assessed the signatures prognostic value and explored their biological significance by correlating them with factors known to be associated with survival (vitamin D) or etiological routes (nevi, sun sensitivity and telomere length). Genomewide microarray gene expressions were profiled in 300 archived tumors (224 primaries, 76 secondaries). The two gene signatures classified up to 96% of our samples and showed strong correlation with melanoma specific survival (P=3 x 10(-4)), Breslow thickness (P=5 x 10(-10)), ulceration (P=9.x10-8) and mitotic rate (P=3 x 10(-7)), adding prognostic value over AJCC stage (adjusted hazard ratio 1.79, 95%CI 1.13-2.83), as previously reported. Furthermore, molecular subtypes were associated with season-adjusted serum vitamin D at diagnosis (P=0.04) and genetically predicted telomere length (P=0.03). Specifically, molecular high-grade tumors were more frequent in patients with lower vitamin D levels whereas high immune tumors came from patients with predicted shorter telomeres. Our data confirm the utility of molecular biomarkers in melanoma prognostic estimation using tiny archived specimens and shed light on biological mechanisms likely to impact on cancer initiation and progression.

Development and validation of a melanoma risk score based on pooled data from 16 case-control studies

BACKGROUND

We report the development of a cutaneous melanoma risk algorithm based upon seven factors; hair color, skin type, family history, freckling, nevus count, number of large nevi, and history of sunburn, intended to form the basis of a self-assessment Web tool for the general public.

METHODS

Predicted odds of melanoma were estimated by analyzing a pooled dataset from 16 case-control studies using logistic random coefficients models. Risk categories were defined based on the distribution of the predicted odds in the controls from these studies. Imputation was used to estimate missing data in the pooled datasets. The 30th, 60th, and 90th centiles were used to distribute individuals into four risk groups for their age, sex, and geographic location. Cross-validation was used to test the robustness of the thresholds for each group by leaving out each study one by one. Performance of the model was assessed in an independent UK case-control study dataset.

RESULTS

Cross-validation confirmed the robustness of the threshold estimates. Cases and controls were well discriminated in the independent dataset [area under the curve, 0.75; 95% confidence interval (CI), 0.73-0.78]. Twenty-nine percent of cases were in the highest risk group compared with 7% of controls, and 43% of controls were in the lowest risk group compared with 13% of cases.

CONCLUSION

We have identified a composite score representing an estimate of relative risk and successfully validated this score in an independent dataset.

IMPACT

This score may be a useful tool to inform members of the public about their melanoma risk.

Epidemiological and genetic factors underlying melanoma development in Italy

Among human cancers, melanoma remains one of the malignancies with an ever-growing incidence in white populations. Recent advances in biological and immunological therapeutic approaches as well as increased efforts for secondary prevention are contributing to improve the survival rates. It is likely that a significant fall in mortality rates for melanoma will be achieved by further increase of the early detection through a more accurate selection of the higher-risk individuals (i.e., carriers of predisposing genetic alterations). A similar scenario occurs in Italy. In the present review, we have considered data on incidence, survival and mortality rates of melanoma in Italian population, including evaluation of the main risk factors and genetic mutations underlying disease susceptibility.

Fine mapping of genetic susceptibility loci for melanoma reveals a mixture of single variant and multiple variant regions

At least 17 genomic regions are established as harboring melanoma susceptibility variants, in most instances with genome-wide levels of significance and replication in independent samples. Based on genome-wide single nucleotide polymorphism (SNP) data augmented by imputation to the 1,000 Genomes reference panel, we have fine mapped these regions in over 5,000 individuals with melanoma (mainly from the GenoMEL consortium) and over 7,000 ethnically matched controls. A penalized regression approach was used to discover those SNP markers that most parsimoniously explain the observed association in each genomic region. For the majority of the regions, the signal is best explained by a single SNP, which sometimes, as in the tyrosinase region, is a known functional variant. However in five regions the explanation is more complex. At the CDKN2A locus, for example, there is strong evidence that not only multiple SNPs but also multiple genes are involved. Our results illustrate the variability in the biology underlying genome-wide susceptibility loci and make steps toward accounting for some of the "missing heritability."