Germline ATM variants predispose to melanoma: a joint analysis across the GenoMEL and MelaNostrum consortia.

PURPOSE: Ataxia-Telangiectasia Mutated (ATM) has been implicated in the risk of several cancers, but establishing a causal relationship is often challenging. Although ATM single-nucleotide polymorphisms have been linked to melanoma, few functional alleles have been identified. Therefore, ATM impact on melanoma predisposition is unclear. METHODS: From 22 American, Australian, and European sites, we collected 2,104 familial, multiple primary (MPM), and sporadic melanoma cases who underwent ATM genotyping via panel, exome, or genome sequencing, and compared the allele frequency (AF) of selected ATM variants classified as loss-of-function (LOF) and variants of uncertain significance (VUS) between this cohort and the gnomAD non-Finnish European (NFE) data set. RESULTS: LOF variants were more represented in our study cohort than in gnomAD NFE, both in all (AF = 0.005 and 0.002, OR = 2.6, 95% CI = 1.56-4.11, p < 0.01), and familial + MPM cases (AF = 0.0054 and 0.002, OR = 2.97, p < 0.01). Similarly, VUS were enriched in all (AF = 0.046 and 0.033, OR = 1.41, 95% CI = 1.6-5.09, p < 0.01) and familial + MPM cases (AF = 0.053 and 0.033, OR = 1.63, p < 0.01). In a case-control comparison of two centers that provided 1,446 controls, LOF and VUS were enriched in familial + MPM cases (p = 0.027, p = 0.018). CONCLUSION: This study, describing the largest multicenter melanoma cohort investigated for ATM germline variants, supports the role of ATM as a melanoma predisposition gene, with LOF variants suggesting a moderate-risk.

Assessing a single SNP located at TERT/CLPTM1L multi-cancer risk region as a genetic modifier for risk of pancreatic cancer and melanoma in Dutch CDKN2A mutation carriers.

Carriers of pathogenic variants in CDKN2A have a 70% life-time risk of developing melanoma and 15-20% risk of developing pancreatic cancer (PC). In the Netherlands, a 19-bp deletion in exon 2 of CDKN2A (p16-Leiden mutation) accounts for most hereditary melanoma cases. Clinical experience suggests variability in occurrence of melanoma and PC in p16-Leiden families. Thereby, the risk of developing cancer could be modified by both environmental and genetic contributors, suggesting that identification of genetic modifiers could improve patients' surveillance. In a recent genome-wide association study (GWAS), rs36115365-C was found to significantly modify risk of PC and melanoma in the European population. This SNP is located on chr5p15.33 and has allele-specific regulatory activities on TERT expression. Herein, we investigated the modifying capacities of rs36115365-C on PC and melanoma in a cohort of 283 p16-Leiden carriers including 29 diagnosed with PC, 171 diagnosed with melanoma, 21 diagnosed with both PC and melanoma and 62 with neither PC nor melanoma. In contrast to previously reported findings, we did not find a significant association of PC risk with risk variant presence as determined by Generalized Estimating Equations (GEE) modelling. Interestingly, carrier-ship of the risk variant had a significant protective effect for melanoma (OR - 0.703 [95% CI - 1.201 to - 0.205], p = 0.006); however, the observed association was no longer significant after exclusion of probands to assess possible influence of ascertainment. Collectively, genetic modifiers for the prediction of PC and melanoma risk in p16-Leiden carriers remain to be determined.

GNAQ and GNA11 mutations and downstream YAP activation in choroidal nevi.

BACKGROUND: Mutations in GNAQ/11 genes are considered an early event in the development of uveal melanoma that may derive from a pre-existing nevus. The Hippo pathway, by way of YAP activation, rather than MAP kinase, has a role in the oncogenic capacity of GNAQ/11 mutations. METHODS: We investigated 16 nevi from 13 human eyes for driver GNAQ/11 mutations using droplet digital PCR and determined whether nevi are clonal by quantifying mutant nevus cell fractions. Immunohistochemistry was performed on 15 nevi to analyse YAP activation. RESULTS: For 15 out of 16 nevi, a GNAQ/11 mutation was detected in the nevus cells albeit at a low frequency with a median of 13%. Nuclear YAP, a transcriptional co-activator in the Hippo tumour-suppressor pathway, was detected in 14/15 nevi. CONCLUSIONS: Our analysis suggests that a mutation in GNAQ/11 occurs in a subset of choroidal nevus cells. We hypothesise that GNAQ/11 mutant-driven extracellular mitogenic signalling involving YAP activation leads to accumulation of wild-type nevus cells.

MC1R gene variants and non-melanoma skin cancer: a pooled-analysis from the M-SKIP project.

BACKGROUND: The melanocortin-1-receptor (MC1R) gene regulates human pigmentation and is highly polymorphic in populations of European origins. The aims of this study were to evaluate the association between MC1R variants and the risk of non-melanoma skin cancer (NMSC), and to investigate whether risk estimates differed by phenotypic characteristics. METHODS: Data on 3527 NMSC cases and 9391 controls were gathered through the M-SKIP Project, an international pooled-analysis on MC1R, skin cancer and phenotypic characteristics. We calculated summary odds ratios (SOR) with random-effect models, and performed stratified analyses. RESULTS: Subjects carrying at least one MC1R variant had an increased risk of NMSC overall, basal cell carcinoma (BCC) and squamous cell carcinoma (SCC): SOR (95%CI) were 1.48 (1.24-1.76), 1.39 (1.15-1.69) and 1.61 (1.35-1.91), respectively. All of the investigated variants showed positive associations with NMSC, with consistent significant results obtained for V60L, D84E, V92M, R151C, R160W, R163Q and D294H: SOR (95%CI) ranged from 1.42 (1.19-1.70) for V60L to 2.66 (1.06-6.65) for D84E variant. In stratified analysis, there was no consistent pattern of association between MC1R and NMSC by skin type, but we consistently observed higher SORs for subjects without red hair. CONCLUSIONS: Our pooled-analysis highlighted a role of MC1R variants in NMSC development and suggested an effect modification by red hair colour phenotype.

Cutaneous melanoma: medical specialists' opinions on follow-up and sentinel lymph node biopsy.

BACKGROUND: The purpose, frequency and content of follow-up (FU) visits have been widely debated for all common malignancies, including melanoma. The aim was to gain insight into Dutch medical specialists' opinions on melanoma FU and to assess their views on sentinel lymph node biopsy (SLNB). METHODS: All members of the Dutch Society of Surgical Oncology and the Dutch Society of Dermatology and Venereology were invited to complete a web-based questionnaire, consisting of 25 questions addressing the following topics: 1) respondent characteristics, 2) knowledge of national melanoma guideline, 3) opinions on melanoma FU, and 4) view on the significance of SLNB. RESULTS: A total of 378 respondents (response = 37%) started the survey, including 173 surgeons (46%) and 205 dermatologists (54%). Of these, 97% and 92% agreed that the purpose of FU is detection of local recurrence and second primary, respectively. Concerning frequency of FU in the first 10 years after diagnosis, 42% preferred a less frequent FU than indicated by the current guideline, while 4% preferred more frequent FU. Overall, twenty-five percent agreed that the standard diagnostics of cutaneous melanoma should include a SLNB, the percentage was highest amongst surgical residents (44%). CONCLUSION: The majority of specialists consider melanoma FU to be primarily an instrument to detect recurrences and secondary primaries. The frequency of FU, as prescribed by the current guideline, could be reduced according to 42%. The importance of SLNB seems to be insufficiently addressed in the Dutch guideline and by Dutch medical specialists despite its role in the AJCC staging system.

Association of MC1R variants and host phenotypes with melanoma risk in CDKN2A mutation carriers: a GenoMEL study.

BACKGROUND: Carrying the cyclin-dependent kinase inhibitor 2A (CDKN2A) germline mutations is associated with a high risk for melanoma. Penetrance of CDKN2A mutations is modified by pigmentation characteristics, nevus phenotypes, and some variants of the melanocortin-1 receptor gene (MC1R), which is known to have a role in the pigmentation process. However, investigation of the associations of both MC1R variants and host phenotypes with melanoma risk has been limited. METHODS: We included 815 CDKN2A mutation carriers (473 affected, and 342 unaffected, with melanoma) from 186 families from 15 centers in Europe, North America, and Australia who participated in the Melanoma Genetics Consortium. In this family-based study, we assessed the associations of the four most frequent MC1R variants (V60L, V92M, R151C, and R160W) and the number of variants (1, ≥2 variants), alone or jointly with the host phenotypes (hair color, propensity to sunburn, and number of nevi), with melanoma risk in CDKN2A mutation carriers. These associations were estimated and tested using generalized estimating equations. All statistical tests were two-sided. RESULTS: Carrying any one of the four most frequent MC1R variants (V60L, V92M, R151C, R160W) in CDKN2A mutation carriers was associated with a statistically significantly increased risk for melanoma across all continents (1.24 × 10(-6) ≤ P ≤ .0007). A consistent pattern of increase in melanoma risk was also associated with increase in number of MC1R variants. The risk of melanoma associated with at least two MC1R variants was 2.6-fold higher than the risk associated with only one variant (odds ratio = 5.83 [95% confidence interval = 3.60 to 9.46] vs 2.25 [95% confidence interval = 1.44 to 3.52]; P(trend) = 1.86 × 10(-8)). The joint analysis of MC1R variants and host phenotypes showed statistically significant associations of melanoma risk, together with MC1R variants (.0001 ≤ P ≤ .04), hair color (.006 ≤ P ≤ .06), and number of nevi (6.9 × 10(-6) ≤ P ≤ .02). CONCLUSION: Results show that MC1R variants, hair color, and number of nevi were jointly associated with melanoma risk in CDKN2A mutation carriers. This joint association may have important consequences for risk assessments in familial settings.

Episodic Src activation in uveal melanoma revealed by kinase activity profiling.

BACKGROUND: The RAS/RAF/MEK/ERK pathway is involved in the balance between melanocyte proliferation and differentiation. The same pathway is constitutively activated in cutaneous and uveal melanoma (UM) and related to tumour growth and survival. Whereas mutant BRAF and NRAS are responsible for the activation of the RAS/RAF/MEK/ERK pathway in most cutaneous melanoma, mutations in these genes are usually absent in UM. METHODS: We set out to explore the RAS/RAF/MEK/ERK pathway and used mitogen-activated protein kinase profiling and tyrosine kinase arrays. RESULTS: We identified Src as a kinase that is associated with ERK1/2 activation in UM. However, low Src levels and reduced ERK1/2 activation in metastatic cell lines suggest that proliferation in metastases can become independent of Src and RAS/RAF/MEK/ERK signalling. Inhibition of Src led to the growth reduction of primary UM cultures and cell lines, whereas metastatic cell line growth was only slightly reduced. CONCLUSION: We identified Src as an important kinase and a potential target for treatment in primary UM. Metastasis cell lines seemed largely resistant to Src inhibition and indicate that in metastases treatment, a different approach may be required.

Activation of the MAPK pathway is a common event in uveal melanomas although it rarely occurs through mutation of BRAF or RAS.

In contrast to cutaneous melanoma, there is no evidence that BRAF mutations are involved in the activation of the mitogen-activated protein kinase (MAPK) pathway in uveal melanoma, although there is increasing evidence that this pathway is activated frequently in the latter tumours. In this study, we performed mutation analysis of the RAS and BRAF genes in a panel of 11 uveal melanoma cell lines and 19 primary uveal melanoma tumours. In addition, Western blot and immunohistochemical analyses were performed on downstream members of the MAPK pathway in order to assess the contribution of each of these components. No mutations were found in any of the three RAS gene family members and only one cell line carried a BRAF mutation (V599E). Despite this, mitogen-activated protein kinase/extracellular signal-regulated kinase kinase (MEK), ERK and ELK were constitutively activated in all samples. These data suggest that activation of the MAPK pathway is commonly involved in the development of uveal melanoma, but occurs through a mechanism different to that of cutaneous melanoma.

Gene expression profiling identifies tumour markers potentially playing a role in uveal melanoma development.

Microarray is a powerful tool to compare the gene expression of different tumour specimens and cell lines simultaneously and quantitatively. To get a better insight into genes that are involved in uveal melanoma tumorigenesis, we compared the gene expression profiles of 12 different uveal melanoma cell lines with three melanocyte cell cultures obtained from healthy donor eyes. Gene expression profiles were obtained by nylon filter arrays, containing 1176 gene spots related to cancer development. The expression levels of selected genes were validated on cell lines and primary uveal melanomas by real time RT-PCR, and were subsequently included in cluster analysis. Four candidate tumour markers, Laminin Receptor 1, Endothelin 2, Von Hippel Lindau Binding protein 1 and Cullin 2, have been selected from genes that were differentially expressed in the uveal melanoma cell lines compared to the normal uveal melanocytes. In primary uveal melanomas, these four markers could discriminate between two classes of uveal melanoma, which may be indicative of a differential disease process.

Melanocortin 1 receptor (MC1R) gene variants are associated with an increased risk for cutaneous melanoma which is largely independent of skin type and hair color.

Individuals carrying melanocortin 1 receptor gene variants have an increased risk for the development of cutaneous melanoma. Melanocortin 1 receptor gene variants are also associated with other risk factors for melanoma such as fair skin and red hair. We evaluated the relationship of melanocortin 1 receptor gene variants, fair skin, red hair and the development of melanoma in 123 patients with cutaneous melanoma and 385 control subjects. To analyze the association between melanocortin 1 receptor gene variants and skin type or hair color we also made use of 453 patients with nonmelanoma skin cancer. We analyzed the coding sequence of the melanocortin 1 receptor gene region by single-stranded conformation polymorphism analysis, followed by DNA sequence analysis. Risk of melanoma dependent on the various melanocortin 1 receptor variant alleles was estimated by exposure odds ratios. The analyses of all different melanocortin 1 receptor gene variants combined, showed that the presence of melanocortin 1 receptor gene variants amounted to a higher melanoma risk, which, in stratified analyses, was independent of skin type and hair color. The odds ratios after adjusting for skin type were 3.6 (95% CI 1.7-7.2) for two variants and 2.7 (95% CI 1.5-5.1) for one variant, respectively. Compound heterozygotes and homozygotes for the Val60Leu, Val92Met, Arg142His, Arg151Cys, Arg160Trp, Arg163Gln, and His260Pro variants had odds ratios of about 4 to develop melanoma, whereas heterozygotes for these variants had half the risk. The presence of the melanocortin 1 receptor gene variant Asp84Glu appeared to impose the highest risk for cutaneous melanoma with odds ratios of 16.1 (95% CI 2.3-139.0) and 8.1 (95% CI 1.2-55.9) in compound heterozygotes and heterozygotes, respectively. The broad confidence intervals, when the different variants were analyzed separately, however, do not allow drawing definite conclusions about the magnitude of these risks. Of the more frequently occurring melanocortin 1 receptor variant alleles the Asp84Glu, Arg142His, Arg151Cys, Arg160Trp, His260Pro, and Asp294His variants were strongly associated with both fair skin and red hair. The Val60Leu, Val92Met, and Arg163Gln variant alleles, however, were only weakly or not associated with fair skin type and/or red hair, which further illustrates the finding that skin type, hair color, and melanoma are independent outcomes of the presence of melanocortin 1 receptor gene variants. We conclude that numerous melanocortin 1 receptor variants predispose to cutaneous melanoma and that possibly the Asp84Glu variant confers the highest risk. This predisposition is largely independent of skin type and hair color.

The melanocortin-1-receptor gene is the major freckle gene.

Ephelides and solar lentigines are different types of pigmented skin lesions. Ephelides appear early in childhood and are associated with fair skin type and red hair. Solar lentigines appear with increasing age and are a sign of photodamage. Both lesions are strong risk indicators for melanoma and non-melanoma skin cancer. Melanocortin-1-receptor (MC1R) gene variants are also associated with fair skin, red hair and melanoma and non-melanoma skin cancer. The purpose of this study was to investigate the relationship between MC1R gene variants, ephelides and solar lentigines. In a large case-control study, patients with melanoma and non-melanoma skin cancer and subjects without a history of skin cancer were studied. In all participants, the presence of ephelides in childhood and solar lentigines by physical examination was assessed according to strict definitions. The entire coding sequence of the MC1R gene was analyzed by single-strand conformation polymorphism analysis followed by sequence analyses. Carriers of one or two MC1R gene variants had a 3- and 11-fold increased risk of developing ephelides, respectively (both P < 0.0001), whereas the risk of developing severe solar lentigines was increased 1.5- and 2-fold (P = 0.035 and P < 0.0001), respectively. These associations were independent of skin type and hair color, and were comparable in patients with and without a history of skin cancer. The population attributable risk for ephelides to MC1R gene variants was 60%, i.e. 60% of the ephelides in the population was caused by MC1R gene variants. A dosage effect was found between the degree of ephelides and the number of MC1R gene variants. As nearly all individuals with ephelides were carriers of at least one MC1R gene variant, our data suggest that MC1R gene variants are necessary to develop ephelides. The results of the study also suggest that MC1R gene variants play a role, although less important, in the development of solar lentigines.

Characterization of melanocortin-1 receptor gene variants in uveal melanoma patients.

PURPOSE: Allelic variations of the melanocortin-1 receptor (MC1R) gene have been linked to red hair and sun-sensitive skin types and may play a role in the susceptibility to develop cutaneous malignant melanoma (CMM). To define the role of MC1R gene in uveal melanoma, a case control study was performed, in which the presence of MC1R gene variations in uveal melanoma patients was compared with that of healthy controls. METHODS: MC1R gene variants were analyzed in 162 uveal melanoma patients and 255 healthy controls. After genomic DNA was isolated from venous blood, the MC1R gene was amplified by polymerase chain reaction (PCR) and examined for the presence of variants by single-strand conformation polymorphism (SSCP) analysis. Participants were asked to complete a questionnaire regarding skin type, eye color, and hair color. RESULTS: No disparity was found between the distribution of the MC1R gene variants in both groups. Furthermore, no associations between MC1R genotype and pigment phenotype were found. In contrast to CMM, uveal melanoma patients did not show specific MC1R gene variants. Compared with controls, most uveal melanoma patients had blue eyes (65%, P = 0.060) and skin type III (56%); however, in the uveal melanoma group the presence of dark blond hair was significantly elevated (46%, P = 0.030). These findings are in contrast with studies on CMM, where most patients have skin type II and red/fair hair. CONCLUSIONS: These data suggest that MC1R variants do not play a role in the susceptibility to develop uveal melanoma. Furthermore, most uveal melanoma patients share phenotypic characteristics that differ from findings in CMM patients.

Melanocortin-1 receptor variant R151C modifies melanoma risk in Dutch families with melanoma.

Germline mutations of the cell-cycle regulator p16 (also called "CDKN2A") in kindreds with melanoma implicate this gene in susceptibility to malignant melanoma. Most families with familial atypical multiple-mole melanoma (FAMMM) who are registered at the Leiden dermatology clinic share the same p16-inactivating deletion (p16-Leiden). Incomplete penetrance and variable clinical expression suggest risk modification by other genetic and/or environmental factors. Variants of the melanocortin-1 receptor (MC1R) gene have been shown to be associated with red hair, fair skin, and melanoma in humans. Carriers of the p16-Leiden deletion in Dutch families with FAMMM show an increased risk of melanoma when they also carry MC1R variant alleles. The R151C variant is overrepresented in patients with melanoma who are from families with the p16-Leiden mutation. Although some of the effect of the R151C variant on melanoma risk may be attributable to its effect on skin type, our analyses indicate that the R151C variant contributes an increased melanoma risk even after statistical correction for its effect on skin type. These findings suggest that the R151C variant may be involved in melanoma tumorigenesis in a dual manner, both as a determinant of fair skin and as a component in an independent additional pathway.

Promoter hypermethylation: a common cause of reduced p16(INK4a) expression in uveal melanoma.

Tumors often display unrestricted cell cycling attributable to a dysfunctional G(1)-S checkpoint. One of the mechanisms leading to such a defect is the inactivation of the cyclin-dependent kinase inhibitor p16(INK4a). Although inactivation of p16(INK4a) is observed in a wide range of tumors, including cutaneous melanoma, genetic alteration of p16(INK4a) is reportedly uncommon in uveal melanoma. Here we show that the p16(INK4a) promoter is hypermethylated in 6 of 12 uveal melanoma cell lines and in 7 of 22 primary uveal melanomas analyzed. Five of seven patients with a methylated primary tumor died of metastatic disease compared with 2 of 15 patients with a nonmethylated primary tumor. We also show that all uveal melanoma cell lines with a hypermethylated p16(INK4a) promoter have lost p16(INK4a) expression but have maintained the expression of p14(ARF). Treatment of uveal melanoma cell lines with 5-aza-2'-deoxycytidine results in demethylation of p16(INK4a) and in reexpression of p16(INK4a) mRNA, which is maintained upon withdrawal of the 5-aza-2'-deoxycytidine. In conclusion, p16(INK4a) promoter methylation appears to be a common event in uveal melanoma and is accompanied by the loss of p16(INK4a) expression.

Cutaneous squamous cell carcinoma and p53 codon 72 polymorphism: a need for screening?

The association between human papillomavirus (HPV)-associated cervical cancer and cutaneous squamous cell carcinoma and codon 72 polymorphism in the p53 gene is not unequivocal. Especially, it is not known whether carriers of the arginine form have an increased risk of cancer that necessitates screening. The alternative is that the polymorphism is a tumor marker instead of a risk factor. We set out a case-control study to determine the risk of squamous cell carcinoma of the skin in individuals with the p53 codon 72 arginine genotype in order to establish the possible need for screening. The distribution of the different p53 codon 72 genotypes was examined in 86 subjects with a history of cutaneous squamous cell carcinoma and in 168 controls. Additionally, 121 subjects who had had histologically proven basal cell carcinoma and 108 subjects who had had non-familial malignant melanoma were tested. p53 polymorphism was evaluated by polymerase chain reaction (PCR) using DNA samples from peripheral blood lymphocytes. In a subgroup of patients with squamous cell carcinoma and controls, the presence of epidermodyplasia verruciformis human papillomavirus (EV-HPV) DNA was determined in plucked eyebrow hair. Differences in the distributions of the genotypes among cases and controls were calculated, and univariate and multivariate analyses were performed to assess the risk to develop cutaneous squamous cell carcinoma in the presence of the p53 codon 72 arginine genotype. Frequency distributions of the three different genotypes (homozygous for the arginine allele, heterozygous for the two alleles, and homozygous for the proline allele) were similar among the squamous cell carcinoma group and the control group: 47.1%, 46.0% and 6.9% versus 47.8%, 45.8% and 6.4%, respectively. Statistical analysis showed no significant differences between these groups. In patients with squamous cell carcinoma and controls who harbored EV-HPV DNA in their plucked eyebrow hair, similar results were obtained. The distributions of the p53 codon 72 genotypes in the basal cell carcinoma and malignant melanoma group were also not significantly different from the control group. p53 codon 72 arginine homozygosity does not appear to represent a significant risk factor for cutaneous squamous cell carcinoma and screening seems not to be indicated. Mol. Carcinog. 30:56-61, 2001.

Melanocortin-1 receptor gene variants determine the risk of nonmelanoma skin cancer independently of fair skin and red hair.

Melanocortin-1 receptor (MC1R) gene variants are associated with fair skin and red hair and, independently of these, with cutaneous malignant melanoma. The association of MC1R gene variants with nonmelanoma skin cancer is largely unknown. A total of 838 subjects were included in the present study: 453 patients with nonmelanoma skin cancer and 385 subjects with no skin cancer. The coding sequence of the human MC1R gene was tested using single-stranded conformation polymorphism analysis followed by sequencing of unknown variants. Risk of skin cancer dependent on the various MC1R gene variants was estimated using the exposure odds ratio. We investigated whether subjects with MC1R variant alleles were at increased risk of developing nonmelanoma skin cancer and, if so, whether this increased risk was mediated by fair skin and red hair. A total of 27 MC1R gene variants were found. The number of carriers of one, two, or three MC1R gene variants was 379 (45.2%), 208 (24.8%), and 7 (0.9%), respectively. A strong association between MC1R gene variants and fair skin and red hair was established, especially the variants Arg151Cys and Arg160Trp (P < .0001). Carriers of two variant alleles were at increased risk for developing cutaneous squamous cell carcinoma (odds ratio 3.77; 95% confidence interval [CI] 2.11-6.78), nodular basal cell carcinoma (odds ratio 2.26; 95% CI 1.45-3.52), and superficial multifocal basal cell carcinoma (odds ratio 3.43; 95% CI 1.92-6.15), compared with carriers of two wild-type alleles. Carriers of one variant allele had half the risk. The highest relative risks of nonmelanoma skin cancer were found in carriers of the Asp84Glu, His260Pro, and Asp294His variant alleles, and the risk was only slightly lower for carriers of the Val60Leu, Val92Met, Arg142His, Arg151Cys, and Arg160Trp variant alleles. When subjects were stratified by skin type and hair color, analysis showed that these factors did not materially change the relative risks. These findings indicate that MC1R gene variants are important independent risk factors for nonmelanoma skin cancer.

[From gene to disease; from p16 to melanoma]. / Van gen naar ziekte; van p16 naar melanoom.

Approximately 10% of human cutaneous melanoma cases occur in families with the familial atypical multiple mole melanoma (FAMMM) syndrome, which is characterised by the familial occurrence of melanomas and atypical precursor naevi. A melanoma-associated gene has been mapped to 9p2l, encoding for the tumour suppressor gene CDKN2A. Worldwide, germline mutations in melanoma kindreds implicate this cell cycle regulator (p16) as a susceptibility gene for malignant melanoma. Most FAMMM families registered at the Leiden Pigmented Lesions Clinic share the same CDKN2A inactivating deletion (P16-Leiden). Presymptomatic DNA diagnosis will now be available for P16-Leiden positive FAMMM family members at the Leiden University Medical Centre.

Risk of developing pancreatic cancer in families with familial atypical multiple mole melanoma associated with a specific 19 deletion of p16 (p16-Leiden).

Familial atypical multiple mole melanoma (FAMMM) is an autosomal dominant disease characterized by the familial occurrence of malignant melanoma of the skin and multiple atypical precursor lesions. Germline mutations in the p16 (CDKN2A) gene have been reported in at least a quarter of such families. An association has been reported between p16 mutations and pancreatic cancer. The aim of this study was to assess the risk of developing pancreatic and other cancers in Dutch FAMMM families with a 19 bp deletion in exon 2 of the p16 gene (p16-Leiden). Mutation analysis was performed in 27 families suspected of FAMMM. Clinical and pathological data were collected from all relatives affected with cancer. A p16-Leiden mutation was identified in 19 families. These families included 86 patients with melanoma. The second most frequent cancer was pancreatic cancer, which was observed in 15 patients from 7 families. The mean age at diagnosis of pancreatic cancer was 58 years (range 38-77 years). The estimated cumulative risk of developing pancreatic cancer in putative mutation carriers by age 75 years was 17%. In 8 p16-Leiden-negative families, no cases of pancreatic cancer occurred. p16 mutation carriers have a considerable risk of developing pancreatic cancer. Further studies should evaluate the value of surveillance of the pancreas in these high-risk families.

Skin equivalent: an attractive model to evaluate early melanoma metastasis.

The growth patterns and morphological phenotype of four human melanoma cell lines with different metastatic potentials were investigated in submerged and in air-exposed (skin equivalent) keratinocyte-melanoma cell co-cultures. In contrast to the submerged co-cultures, all four cell lines formed sharply demarcated tumour cell nests within the epidermal compartment of the skin equivalent model, with the morphology highly mimicking the in vivo situation. Differences among the melanoma cell lines tested were observed with respect to the number of clusters formed and the ability to exhibit invasive growth. Only the two metastatic cell lines were able to invade the dermal compartment. Screening of cellular adhesion molecules revealed that the expression patterns in different cell lines were heterogeneous and remained unchanged during the whole culture period, irrespective of whether the melanoma cells were located in the epidermal or dermal compartment. A correlation was found between expression of a lower number of different cellular adhesion molecules and the ability to acquire invasive growth capability. Our results indicate that melanoma cells exhibit a heterogeneous growth behaviour when co-cultured with human keratinocytes, and the air-exposed skin equivalent model was shown to be suitable for studying differences in growth patterns and potential invasive behaviour.