Genetic analysis of three important genes in pigmentation and melanoma susceptibility: CDKN2A, MC1R and HERC2/OCA2.

The CDKN2A gene is regarded as the major familial malignant melanoma (MM) susceptibility gene. Human pigmentation is one of the main modulators of individual risk of developing MM. Therefore, the genes involved in the determination of skin colour and tanning response are potentially implicated in MM predisposition and may be useful predictors of MM risk in the general population. The human melanocortin-1 receptor gene (MC1R) plays a crucial role in pigmentation and also appears to be important in MM. The OCA2 gene has emerged as a new and significant determinant of human iris colour variation. We present a case-control study in Spanish population including 390 consecutive patients with melanoma and 254 control subjects. Sequence analysis of the entire coding region and genotyping of 5 tag-SNPs in the genomic region of MC1R was performed. We identified 27 variants, two reaching statistical significance [R160W (OR: 4.18, 95% CI: 1.24-14.04, P = 0.02) and D294H (OR: 3.10, 95% CI: 1.37-7.01, P = 0.01)] and we detected two novel non-synonymous changes: V92L and T308M. Odds ratio for carrying two functional variants was 4.25 (95% CI: 2.30-7.84, P = 3.63 x 10(-6)). Haplotypes of the entire MC1R region have been established, and we observed an enrichment of a rare European haplotype similar to African values carrying variants V92M and I155T. In addition, three potentially functional SNPs were selected in p16/CDKN2A and in the promoter region of OCA2/HERC2. Our data for CDKN2A gene did not reach statistically significant results for any of the two studied alleles. We found that the variant allele A > G of OCA2/HERC2 (rs12913832) was associated with pigmentation features: eye, hair and skin colour; P-values = 1.8 x 10(-29), 9.2 x 10(-16), 1.1 x 10(-3), respectively, validating previous results.

Pigmentation-related genes and their implication in malignant melanoma susceptibility.

Human pigmentation appears to be one of the main modulators of individual risk of developing malignant melanoma (MM). A large number of genes are known to be involved in rare pigmentary disorders and explain most of the variation in pigmentation phenotypes seen in human populations. This Spanish case-control study included 205 patients with melanoma and 245 control subjects. Thirty-one single nucleotide polymorphisms (SNPs) in genes that had been mainly associated with congenital pigmentation syndromes (ADTB3A, ATRN, CHS1, EDNRB, HPS, KIT, MGRN1, MITF, MLANA, MYO5A, MYO7A, OA1, OCA2, PAX3 and SOX10) were selected. We found that the variant allele of OCA2 R419Q (rs1800407) was associated with increased risk of MM (OR 1.55, 95% CI 1.04-2.31, P = 0.03). This effect on melanoma risk appeared to be stronger among individuals with solar lentigines, or at least 50 nevi. We also describe, for the first time, an association with the variant S1666C (rs2276288) in the MYO7A gene (OR 1.35; 95% CI 1.04-1.76; P = 0.03). Again, this association appeared to be stronger in several phenotypic groups such as individuals with fair skin and those with childhood sunburns. We also found that several variants in the pigmentation genes considered were associated with intermediate phenotypic characteristics. Our findings highlight the potential importance of pigmentation genes in sporadic MM susceptibility.

Genetic analysis of the vitamin D receptor gene in two epithelial cancers: melanoma and breast cancer case-control studies.

BACKGROUND: Vitamin D serum levels have been found to be related to sun exposure and diet, together with cell differentiation, growth control and consequently, cancer risk. Vitamin D receptor (VDR) genotypes may influence cancer risk; however, no epidemiological studies in sporadic breast cancer (BC) or malignant melanoma (MM) have been performed in a southern European population. In this study, the VDR gene has been evaluated in two epithelial cancers BC and MM. METHODS: We have conducted an analysis in 549 consecutive and non-related sporadic BC cases and 556 controls, all from the Spanish population, and 283 MM cases and 245 controls. Genotyping analyses were carried out on four putatively functional SNPs within the VDR gene. RESULTS: An association with the minor allele A of the non-synonymous SNP rs2228570 (rs10735810, FokI, Met1Thr) was observed for BC, with an estimated odds ratio (OR) of 1.26 (95% CI = 1.02-1.57; p = 0.036). The synonymous variant rs731236 (TaqI) appeared to be associated with protection from BC (OR = 0.80, 95%CI = 0.64-0.99; p = 0.047). No statistically significant associations with MM were observed for any SNP. Nevertheless, sub-group analyses revealed an association between rs2228570 (FokI) and absence of childhood sunburns (OR = 0.65, p = 0.003), between the 3'utr SNP rs739837 (BglI) and fair skin (OR = 1.31, p = 0.048), and between the promoter SNP rs4516035 and the more aggressive tumour location in head-neck and trunk (OR = 1.54, p = 0.020). CONCLUSION: In summary, we observed associations between SNPs in the VDR gene and BC risk, and a comprehensive analysis using clinical and tumour characteristics as outcome variables has revealed potential associations with MM. These associations required confirmation in independent studies.

Mesenchymal contribution to recruitment, infiltration, and positioning of leukocytes in human melanoma tissues.

To understand factors that regulate leukocyte entry and positioning within human melanoma tissues, we performed a multiparametric quantitative analysis of two separated regions: the intratumoral area and the peritumoral stroma. Using two mesenchymal markers, fibroblast activation protein (FAP) and CD90, we identified three subsets of mesenchymal cells (MCs): (i) intratumoral FAP(+)CD90(low/-) MC, (ii) peritumoral FAP(+)CD90(+) MC, and (iii) FAP(-)CD90(+) perivascular MC. We characterized CD90(+) MCs, which showed a stable CCL2-secretory phenotype when long-term expanded ex vivo, and heavily surrounded peritumoral Duffy antigen receptor for chemokine(+) (DARC) postcapillary venules, supporting a role for these vessels in peritumoral inflammatory leukocyte recruitment. Conversely, the intratumoral area was variably invaded by FAP(+)CD90(low/-) MCs that colocalized with a distinct extracellular matrix (ECM) network. A positive correlation was observed between intratumoral stromal cell/ECM networks and leukocyte infiltration among tumor cells (TCs), as well as in a stroma-dependent xenograft tumor model. Adoptively transferred T lymphocytes preferentially infiltrated tumors composed of TC+MC, compared with TCs only. Altogether, our results suggest that a variety of MCs contribute to regulate different steps of leukocyte tumor infiltration, that is, CD90(+) cells surrounding peritumoral vessels secrete CCL2 to recruit CCR2(+) leukocytes at the tumor periphery, whereas intratumoral FAP(+) cells organize a stromal scaffold that contact guide further invasion among densely packed tumor cells.

MC1R, SLC45A2 and TYR genetic variants involved in melanoma susceptibility in southern European populations: results from a meta-analysis.

BACKGROUND AND METHODS: Seven genetic biomarkers previously associated with melanoma were analysed in a meta-analysis conducted in three South European populations: five red hair colour (RHC) MC1R alleles, one SLC45A2 variant (p.Phe374Leu) and one thermosensitive TYR variant (p.Arg402Gln). The study included 1639 melanoma patients and 1342 control subjects. RESULTS: The estimated odds ratio (OR) associated with carrying at least one MC1R RHC variant was 2.18 (95% confidence interval (CI): 1.86-2.55; p-value=1.02×10(-21)), with an additive effect for carrying two RHC variants (OR: 5.02, 95% CI: 2.88-8.94, p-value=3.91×10(-8)). The SLC45A2 variant, p.Phe374Leu, was significantly and strongly protective for melanoma in the three South European populations studied, with an overall OR value of 0.41 (95% CI: 0.33-0.50; p-value=3.50×10(-17)). The association with melanoma of the TYR variant p.Arg402Gln was also statistically significant (OR: 1.50; 95% CI: 1.11-2.04; p-value=0.0089). Adjustment for all clinical potential confounders showed that melanoma risks attributable to MC1R and SLC45A2 variants strongly persisted (OR: 2.01 95% CI: 1.49-2.72 and OR: 0.50, 95% CI: 0.31-0.80, respectively), while the association of TYR p.Arg402Gln was no longer significant. In addition, stratification of clinical melanoma risk factors showed that the risk of melanoma was strong in those individuals who did not have clinical risk factors. CONCLUSION: In conclusion, our results show without ambiguity that in South European populations, MC1R RHC and SCL45A2 p.Phe374Leu variants are strong melanoma risk predictors, notably in those individuals who would not be identified as high risk based on their phenotypes or exposures alone. The use of these biomarkers in clinical practice could be promising and warrants further discussion.

Genetic polymorphisms in DNA repair and oxidative stress pathways associated with malignant melanoma susceptibility.

BACKGROUND: Base excision repair (BER) and nucleotide excision repair (NER) pathways eliminate a wide variety of DNA damage, including UV photoproducts. The ability of each individual to repair DNA damage following different causes might explain at least in part the variability in cancer susceptibility. Moreover, inflammatory response to UV exposure may further contribute to skin carcinogenesis by oxidative stress mechanisms. Single nucleotide polymorphisms in genes encoding various DNA-repair enzymes and oxidative stress factors may be candidate low-penetrance variants with a role in susceptibility to different cancers, particularly in those with aetiologies linked to environmental exposure, such as malignant melanoma (MM). METHODS: In this case-control study, 684 Spanish sporadic MM patients and 406 cancer-free control subjects were included and the role of 46 polymorphisms belonging to 16 BER and NER genes as well as 11 genes involved in oxidative stress processes were investigated. RESULTS: One polymorphism was identified to be individually associated with MM in the Spanish population. The variant was found in the NOS1 oxidative stress gene (rs2682826; p-value=0.01). These results suggest a putative role of oxidative stress processes in the genetic predisposition to melanoma. CONCLUSION: To the authors' knowledge, this is the largest DNA repair-related SNP study in melanoma risk conducted in the Spanish population up to now. Furthermore, it also represents a comprehensive genetic study of several oxidative stress polymorphisms tested in relation to MM susceptibility.

A customized pigmentation SNP array identifies a novel SNP associated with melanoma predisposition in the SLC45A2 gene.

As the incidence of Malignant Melanoma (MM) reflects an interaction between skin colour and UV exposure, variations in genes implicated in pigmentation and tanning response to UV may be associated with susceptibility to MM. In this study, 363 SNPs in 65 gene regions belonging to the pigmentation pathway have been successfully genotyped using a SNP array. Five hundred and ninety MM cases and 507 controls were analyzed in a discovery phase I. Ten candidate SNPs based on a p-value threshold of 0.01 were identified. Two of them, rs35414 (SLC45A2) and rs2069398 (SILV/CKD2), were statistically significant after conservative Bonferroni correction. The best six SNPs were further tested in an independent Spanish series (624 MM cases and 789 controls). A novel SNP located on the SLC45A2 gene (rs35414) was found to be significantly associated with melanoma in both phase I and phase II (P<0.0001). None of the other five SNPs were replicated in this second phase of the study. However, three SNPs in TYR, SILV/CDK2 and ADAMTS20 genes (rs17793678, rs2069398 and rs1510521 respectively) had an overall p-value<0.05 when considering the whole DNA collection (1214 MM cases and 1296 controls). Both the SLC45A2 and the SILV/CDK2 variants behave as protective alleles, while the TYR and ADAMTS20 variants seem to function as risk alleles. Cumulative effects were detected when these four variants were considered together. Furthermore, individuals carrying two or more mutations in MC1R, a well-known low penetrance melanoma-predisposing gene, had a decreased MM risk if concurrently bearing the SLC45A2 protective variant. To our knowledge, this is the largest study on Spanish sporadic MM cases to date.

[Genetic predisposition in cutaneous melanoma]. / Predisposición genética en el melanoma cutáneo.

The incidence of cutaneous melanoma has increased worldwide in the last 20 years. Research on potential risk factors, both environmental and genetic, has led us to some new and interesting conclusions. Ultraviolet radiation is clearly the main environmental risk factor for melanoma, but its relationship is complex and controversial. With regard to genetic factors, the discovery of two types of genes was a great advance in further understanding the biology of the melanocyte. CDKN2A (p16) is the prototype of the high-penetrance, low-prevalence gene related to melanoma. This gene has been studied in some families in which several members have been diagnosed with melanoma. In the general population with non-familial melanoma, low-penetrance, high-prevalence genes such as MC1R seem to be more interesting. Studies on the MC1R gene have not only shown its importance in skin and hair pigmentation, but also in the development of melanoma. Functional studies on CDKN2A and MC1R have led us to new and important conclusions. The analysis of data from studies on families, twins and control cases, with the collaboration of several countries, will lead us to new discoveries. For the primary and secondary prevention of this tumor, we must promote public health campaigns on the dangers of sun exposure and the identification of individuals at high risk.

[Prognosis for cutaneous melanoma according to surgical department: comparative study at a tertiary care hospital]. / Pronóstico del melanoma cutáneo según el servicio quirúrgico: estudio comparativo en un hospital de tercer nivel.

INTRODUCTION: Surgical treatment of melanoma is performed by dermatologists and general or plastic surgeons. It is not known whether the type of specialist treating the melanoma results in a different prognosis for these patients. MATERIAL AND METHODS: A retrospective study was carried out on the epidemiological, clinical/histological and evolutional characteristics of all patients diagnosed with melanoma at Hospital Gregorio Marañón over a 10-year period (1994-2003). The differences by hospital department where the patients were treated (dermatology, general surgery and plastic surgery) were noted. RESULTS: Over 90 % of the patients with melanoma were treated by the Dermatology Department. The thickness of the tumors and the presence of histologic ulceration were significantly higher in the melanomas treated by general and plastic surgeons (p <0.05). The differences in overall average survival (105, 55 and 77 months) and disease-free time (88, 24 and 51.3 months) in the melanomas operated on by dermatologists, general surgeons and plastic surgeons, respectively, were significant (p <0.001). CONCLUSIONS: This study confirms that there are significant differences in the clinical and histological characteristics and the life prognosis of patients with cutaneous melanoma treated by different specialists. The melanomas treated by general or plastic surgeons have usually been developing for a longer time, and therefore are thicker and more often ulcerated than those treated by dermatologists, resulting in a lower survival period. With appropriate medical and surgical training, dermatologists are the most suitable specialists for early diagnosis and treatment.

Predisposición genética en el melanoma cutáneo / Genetic predisposition in cutaneous melanoma

La incidencia del melanoma cutáneo ha aumentado en todo el mundo durante los últimos 20 años. La investigación sobre los factores de riesgo potenciales, tanto ambientales como genéticos, nos ha conducido a algunas nuevas e interesantes conclusiones. La radiación ultravioleta es claramente el factor de riesgo ambiental principal para el melanoma, pero su relación es compleja y controvertida. Respecto a los factores genéticos, el descubrimiento de dos clases de genes ha sido un gran avance con más entendimiento de biología del melanocito. CDKN2A (p16) es el prototipo de gen de alta penetrancia y baja prevalencia relacionado con el melanoma. Este gen ha sido estudiado en algunas familias con varios miembros diagnosticados de melanoma. En la población general con melanoma no familiar, los genes de baja penetrancia pero alta prevalencia como el MC1R parecen ser más interesantes. Los estudios sobre el gen MC1R no sólo han mostrado su importancia en la pigmentación de la piel y el pelo, sino también en el desarrollo de melanoma. Los estudios funcionales sobre CDKN2A y MC1R nos han llevado a nuevas conclusiones importantes. El análisis de los datos procedentes de estudios familiares, gemelos y casos-control, con la colaboración de varios países nos llevará a nuevos descubrimientos. Para la prevención primaria y secundaria de este tumor, debemos fomentar la realización de campañas de salud públicas sobre la exposición al sol y el reconocimiento de individuos con alto riesgo

The incidence of cutaneous melanoma has increased worldwide in the last 20 years. Research on potential risk factors, both environmental and genetic, has led us to some new and interesting conclusions. Ultraviolet radiation is clearly the main environmental risk factor for melanoma, but its relationship is complex and controversial. With regard to genetic factors, the discovery of two types of genes was a great advance in further understanding the biology of the melanocyte. CDKN2A (p16) is the prototype of the high-penetrance, low-prevalence gene related to melanoma. This gene has been studied in some families in which several members have been diagnosed with melanoma. In the general population with non-familial melanoma, low-penetrance, high-prevalence genes such as MC1R seem to be more interesting. Studies on the MC1R gene have not only shown its importance in skin and hair pigmentation, but also in the development of melanoma. Functional studies on CDKN2A and MC1R have led us to new and important conclusions. The analysis of data from studies on families, twins and control cases, with the collaboration of several countries, will lead us to new discoveries. For the primary and secondary prevention of this tumor, we must promote public health campaigns on the dangers of sun exposure and the identification of individuals at high risk

Pronóstico del melanoma cutáneo según el servicio quirúrgico: estudio comparativo en un hospital de tercer nivel / Prognosis for cutaneous melanoma according to surgical department: comparative study at a tertiary care hospital

Introducción. El tratamiento quirúrgico del melanoma depende de dermatólogos y cirujanos generales o plásticos. Se desconoce si el tratamiento del melanoma por unos u otros especialistas determina un pronóstico distinto para estos pacientes. Material y métodos. Se analizaron de forma retrospectiva las características epidemiológicas, clínico-histológicas y evolutivas de todos los pacientes diagnosticados de melanoma en el Hospital Gregorio Marañón durante un periodo de 10 años (1994-2003). Se observaron las diferencias existentes en función del servicio hospitalario en el que fueron atendidos (dermatología, cirugía general y cirugía plástica). Resultados. Más del 90 % de los pacientes con melanoma fueron atendidos por el Servicio de Dermatología. El espesor tumoral y la presencia de ulceración histológica fueron significativamente superiores en los melanomas atendidos por cirujanos generales y plásticos (p < 0,05). Las diferencias en la supervivencia global media (105, 55 y 77 meses) y el tiempo libre de enfermedad (88, 24 y 51,3 meses) en los melanomas operados por dermatólogos, cirujanos generales y plásticos, respectivamente, fueron significativas (p < 0,001). Conclusiones. El presente estudio confirma las diferencias significativas en las características clínico-histológicas y el pronóstico vital de los pacientes con melanoma cutáneo atendidos por diferentes especialistas. Los atendidos por cirujanos generales o plásticos suelen ser melanomas de mayor tiempo de evolución y, por tanto, de mayor espesor y frecuencia de ulceración que los atendidos por dermatólogos, lo que determina una supervivencia inferior. Una formación médico-quirúrgica adecuada convierte al dermatólogo en el especialista más adecuado para su diagnóstico y tratamiento precoz

Introduction. Surgical treatment of melanoma is performed by dermatologists and general or plastic surgeons. It is not known whether the type of specialist treating the melanoma results in a different prognosis for these patients. Material and methods. A retrospective study was carried out on the epidemiological, clinical/histological and evolutional characteristics of all patients diagnosed with melanoma at Hospital Gregorio Marañón over a 10-year period (1994--2003). The differences by hospital department where the patients were treated (dermatology, general surgery and plastic surgery) were noted. Results. Over 90 % of the patients with melanoma were treated by the Dermatology Department. The thickness of the tumors and the presence of histologic ulceration were significantly higher in the melanomas treated by general and plastic surgeons (p < 0.05). The differences in overall average survival (105, 55 and 77 months) and disease-free time (88, 24 and 51.3 months) in the melanomas operated on by dermatologists, general surgeons and plastic surgeons, respectively, were significant (p < 0.001). Conclusions. This study confirms that there are significant differences in the clinical and histological characteristics and the life prognosis of patients with cutaneous melanoma treated by different specialists. The melanomas treated by general or plastic surgeons have usually been developing for a longer time, and therefore are thicker and more often ulcerated than those treated by dermatologists, resulting in a lower survival period. With appropriate medical and surgical training, dermatologists are the most suitable specialists for early diagnosis and treatment