Genetic and environmental factors in cutaneous malignant melanoma

Persistent β-Hexachlorocyclohexane Exposure Impacts Cellular Metabolism with a Specific Signature in Normal Human Melanocytes

BACKGROUND

Cutaneous melanoma arises from skin melanocytes and has a high risk of metastatic spread. Despite better prevention, earlier detection, and the development of innovative therapies, melanoma incidence and mortality increase annually. Major clinical risk factors for melanoma include fair skin, an increased number of nevi, the presence of dysplastic nevi, and a family history of melanoma. However, several external inducers seem to be associated with melanoma susceptibility such as environmental exposure, primarily unprotected sun experience, alcohol consumption, and heavy metals. In recent years, epidemiological studies have highlighted a potential risk of β-hexachlorocyclohexane (β-HCH), the most studied organochlorine pesticide, causing cancer induction including melanoma.

METHODS

We evaluated in vitro the impact of this pollutant on epidermal and dermal cells, attempting to describe mechanisms that could render cutaneous cells more prone to oncogenic transformation.

RESULTS

We demonstrated that β-HCH impacts melanocyte biology with a highly cell-type specific signature that involves perturbation of AKT/mTOR and Wnt/β-catenin signaling, and AMPK activation, resulting in lowering energy reserve, cell proliferation, and pigment production.

CONCLUSIONS

In conclusion, long-term exposure to persistent organic pollutants damages melanocyte metabolism in its function of melanin production with a consequent reduction of melanogenesis indicating a potential augmented skin cancer risk.

PTPRC functions as a prognosis biomarker in the tumor microenvironment of cutaneous melanoma

Cutaneous melanoma is one of the most malignant types of skin cancer, with an extremely poor prognosis. Immune cells infiltrated in the tumor microenvironment (TME) affects melanoma initiation, progression, prognosis and immunotherapy strategies in melanoma. The potential utility of TME-related genes as a prognostic model for melanoma and as a predictor of immunotherapeutic response merits further exploration. In this study, we determined that an immune-related gene, protein tyrosine phosphatase receptor type C (PTPRC), was positively correlated with the positive prognosis of melanoma patients. Integration of this gene with TNM classification created a predictive model that showed better performance in determining overall survival than others. PTPRC expression was positively correlated with the levels of immune checkpoint molecules, and PTPRC knockdown significantly enhanced the migration, invasion, and proliferation of melanoma cells. Finally, immunohistochemical results from HPA and Real-time quantitative PCR of clinical tissues confirmed that PTPRC expression was higher in melanoma than in normal skin. In conclusion, PTPRC served as a potential predictor of survival and response to immunotherapy in melanoma patients. The risk model combining the PTPRC and TNM classifications holds the potential to be a promising tool for prognostic prediction of cutaneous melanoma. This will help in the effective clinical management of melanoma patients.

Natural tyrosinase enzyme inhibitors: A path from melanin to melanoma and its reported pharmacological activities

The skin containing melanin pigment acts as a protective barrier and counteracts the UVR and other environmental stressors to maintain or restore disrupted cutaneous homeostasis. The production of melanin pigment is dependent on tyrosine levels. L-tyrosine and L-dihydroxyphenylalanine (L-DOPA) can serve both as a substrates and intermediates of melanin synthetic pathway and as inducers and positive regulators of melanogenesis. The biosynthesis of melanin is stimulated upon exposure to UVR, which can also stimulate local production of hormonal factors, which can stimulate melanoma development by altering the chemical properties of eu- and pheomelanin. The process of melanogenesis can be altered by several pathways. One involves activation of POMC, with the production of POMC peptides including MSH and ACTH, which increase intracellular cAMP levels, which activates the MITF, and helps to stimulate tyrosinase (TYR) expression and activity. Defects in OCA1 to 4 affects melanogenic activity via posttranslational modifications resulting in proteasomal degradation and reducing pigmentation. Further, altering, the MITF factor, helps to regulate the expression of MRGE in melanoma, and helps to increase the TYR glycosylation in ER. CRH stimulates POMC peptides that regulate melanogenesis and also by itself can stimulate melanogenesis. The POMC, P53, ACTH, MSH, MC1R, MITF, and 6-BH4 are found to be important regulators for pigmentation. Melanogenesis can affect melanoma behaviour and inhibit immune responses. Therefore, we reviewed natural products that would alter melanin production. Our special focus was on targeting melanin synthesis and TYR enzyme activity to inhibit melanogenesis as an adjuvant therapy of melanotic melanoma. Furthermore, this review also outlines the current updated pharmacological studies targeting the TYR enzyme from natural sources and its consequential effects on melanin production.

Functional annotation and investigation of the 10q24.33 melanoma risk locus identifies a common variant that influences transcriptional regulation of OBFC1

The 10q24.33 locus is known to be associated with susceptibility to cutaneous malignant melanoma (CMM), but the mechanisms underlying this association have been not extensively investigated. We carried out an integrative genomic analysis of 10q24.33 using epigenomic annotations and in vitro reporter gene assays to identify regulatory variants. We found two putative functional single nucleotide polymorphisms (SNPs) in an enhancer and in the promoter of OBFC1, respectively, in neural crest and CMM cells, one, rs2995264, altering enhancer activity. The minor allele G of rs2995264 correlated with lower OBFC1 expression in 470 CMM tumors and was confirmed to increase the CMM risk in a cohort of 484 CMM cases and 1801 controls of Italian origin. Hi-C and chromosome conformation capture (3C) experiments showed the interaction between the enhancer-SNP region and the promoter of OBFC1 and an isogenic model characterized by CRISPR-Cas9 deletion of the enhancer-SNP region confirmed the potential regulatory effect of rs2995264 on OBFC1 transcription. Moreover, the presence of G-rs2995264 risk allele reduced the binding affinity of the transcription factor MEOX2. Biologic investigations showed significant cell viability upon depletion of OBFC1, specifically in CMM cells that were homozygous for the protective allele. Clinically, high levels of OBFC1 expression associated with histologically favorable CMM tumors. Finally, preliminary results suggested the potential effect of decreased OBFC1 expression on telomerase activity in tumorigenic conditions. Our results support the hypothesis that reduced expression of OBFC1 gene through functional heritable DNA variation can contribute to malignant transformation of normal melanocytes.

A Review of Epidemiology and Cancer Biology of Malignant Melanoma

Malignant melanoma is a neoplasm originating in the melanocytes in the skin. Although malignant melanoma is the third most common cutaneous cancer, it is recognized as the main cause of skin cancer-related mortality, and its incidence is rising. The natural history of malignant melanoma involves an inconsistent and insidious skin cancer with great metastatic potential. Increased ultra-violet (UV) skin exposure is undoubtedly the greatest risk factor for developing cutaneous melanoma; however, a plethora of risk factors are now recognized as causative. Moreover, modern oncology now considers melanoma proliferation a complex, multifactorial process with a combination of genetic, epigenetic, and environmental factors all known to be contributory to tumorgenesis. Herein, we wish to outline the epidemiological, molecular, and biological processes responsible for driving malignant melanoma proliferation.

Incidence and survival of cutaneous melanoma in Belgium and the Netherlands from 2004 to 2016: striking differences and similarities of two neighbouring countries

BACKGROUND

Cutaneous melanoma (CM) is a multifactorial disease, with both environmental and genetic factors involved. The incidence of CM has risen rapidly during the last decades, making it a growing public health problem.

OBJECTIVES

The purpose of this retrospective study was to compare incidence and survival data of CM between two neighbouring countries, Belgium (BE) and the Netherlands (NL).

METHODS

Data were collected by the Belgian Cancer Registry (BCR) and the Netherlands Cancer Registry (NCR) from 1 January 2004 until 31 December 2016. Mucosal melanoma, in situ CM and melanoma in children from 0 to 14 years were excluded. Age-standardized incidence rates were calculated using the World Standard Population (WSR) per 100 000 persons. Five-year relative survival ratios were calculated using the Ederer II methodology.

RESULTS

Total number of CM was higher in NL (63 789) compared with BE (27 679). The WSR was 1.5 times higher in NL compared with BE (27.7 vs. 18.6/100 000/year). The WSR of stage IV tumours was higher in BE than in NL (0.3 vs. 0.2/100 000/year). Five-year relative survival of stage IV tumours was higher in BE compared with NL (27.2% vs. 13.7%).

CONCLUSIONS

Incidence of CM was higher in NL, indicating a higher risk of CM diagnosis. Stage IV tumours were relatively more frequent in BE for both sexes, while relative survival of stage IV tumours was higher in BE. As geographical location and latitude of both neighbouring countries are almost identical, other factors like differences in behaviour, follow-up and/or treatment may explain these differences.

The α9 Nicotinic Acetylcholine Receptor Mediates Nicotine-Induced PD-L1 Expression and Regulates Melanoma Cell Proliferation and Migration

Cigarette smoking is associated with an increased risk of melanoma metastasis. Smokers show higher PD-L1 expression and better responses to PD-1/PD-L1 inhibitors than nonsmokers. Here, we investigate whether nicotine, a primary constituent of tobacco, induces PD-L1 expression and promotes melanoma cell proliferation and migration, which is mediated by the α9 nicotinic acetylcholine receptor (α9-nAChR). α9-nAChR overexpression in melanoma using melanoma cell lines, human melanoma tissues, and assessment of publicly available databases. α9-nAChR expression was significantly correlated with PD-L1 expression, clinical stage, lymph node status, and overall survival (OS). Overexpressing or knocking down α9-nAChR in melanoma cells up- or downregulated PD-L1 expression, respectively, and affected melanoma cell proliferation and migration. Nicotine-induced α9-nAChR activity promoted melanoma cell proliferation through stimulation of the α9-nAChR-mediated AKT and ERK signaling pathways. In addition, nicotine-induced α9-nAchR activity promoted melanoma cell migration via activation of epithelial-mesenchymal transition (EMT). Moreover, PD-L1 expression was upregulated in melanoma cells after nicotine treatment via the transcription factor STAT3 binding to the PD-L1 promoter. These results highlight that nicotine-induced α9-nAChR activity promotes melanoma cell proliferation, migration, and PD-L1 upregulation. This study may reveal important insights into the mechanisms underlying nicotine-induced melanoma growth and metastasis through α9-nAChR-mediated carcinogenic signals and PD-L1 expression.

Focus on cutaneous and uveal melanoma specificities

Cutaneous melanoma (CM) and uveal melanoma (UM) derive from cutaneous and uveal melanocytes that share the same embryonic origin and display the same cellular function. However, the etiopathogenesis and biological behaviors of these melanomas are very different. CM and UM display distinct landscapes of genetic alterations and show different metastatic routes and tropisms. Hence, therapeutic improvements achieved in the last few years for the treatment of CM have failed to ameliorate the clinical outcomes of patients with UM. The scope of this review is to discuss the differences in tumorigenic processes (etiologic factors and genetic alterations) and tumor biology (gene expression and signaling pathways) between CM and UM. We develop hypotheses to explain these differences, which might provide important clues for research avenues and the identification of actionable vulnerabilities suitable for the development of new therapeutic strategies for metastatic UM.

Melanoma Epidemiology and Prevention

The epidemiology of melanoma is complex, and individual risk depends on sun exposure, host factors, and genetic factors, and in their interactions as well. Sun exposure can be classified as intermittent, chronic, or cumulative (overall) exposure, and each appears to have a different effect on type of melanoma. Other environmental factors, such as chemical exposures-either through occupation, atmosphere, or food-may increase risk for melanoma, and this area warrants further study. Host factors that are well known to be important are the numbers and types of nevi and the skin phenotype. Genetic factors are classified as high-penetrant genes, moderate-risk genes, or low-risk genetic polymorphisms. Subtypes of tumors, such as BRAF-mutated tumors, have different risk factors as well as different therapies. Prevention of melanoma has been attempted using various strategies in specific subpopulations, but to date optimal interventions to reduce incidence have not emerged.

P, Tarantini L, Calista D, Cavalleri T, Angelici L, Consonni D, Pier A. B, Angela C. P, Maria T. L, Bollati V. Blood DNA methylation, nevi number, and the risk of melanoma

Germline mutations determining increased cutaneous malignant melanoma (CMM) risk have been identified in familial and sporadic CMM cases, but they account only for a small proportion of CMM cases. Recent evidence suggests that germline epimutations (e.g. DNA methylation alterations), which can be inherited similarly to genomic mutations and can be detected in normal body cells (including blood), might increase susceptibility to cancer. The aim of the study was to identify germline epimutations of genes that were found to be mutated in familial CMM (p16, p14, CDK4, MC1R, hTERT), immune and inflammatory genes (ICAM-1, TNFα), DNA mismatch repair gene (MLH1), and repetitive elements (ALU, LINE-1, HERV-w). We measured DNA methylation using bisulfite pyrosequencing in peripheral blood mononuclear cells from 167 CMM cases and 164 sex-matched and age-matched controls. We used multivariable logistic regression models to evaluate the association between methylation levels and CMM status or presence of dysplastic nevi. We found an association between the risk of CMM and peripheral blood mononuclear cell methylation levels of TNFα [odds ratio (OR)=1.11, 95% confidence interval (CI)=1.03-1.18], CDK4 (OR=0.76, 95% CI=0.64-0.91), and MLH1 (OR=1.12, 95% CI=1.02-1.22). In control participants, the risk of developing dysplastic nevi was associated with methylation levels of TNFα (OR=0.81, 95% CI=0.69-0.95), hTERT (OR=0.90, 95% CI=0.82-0.99), and ALU (OR=1.56, 95% CI=1.02-2.39). Epimutations in CMM susceptibility genes and in genes involved in response to oxidative damage are associated with the risk of developing CMM or dysplastic nevi. Further studies measuring methylation levels of these genes in prospectively collected samples are warranted to further elucidate their role in the development and progression of CMM.

A germline oncogenic MITF mutation and tumor susceptibility

MITF (Microphthalmia-associated transcription factor) is a lineage specific transcription factor that plays a critical role in melanocyte homeostasis and whose deregulation has been shown to contribute to melanoma disease. A germline mutation in MITF, impairing SUMOylation and predisposing to cutaneous malignant melanoma, was recently identified. Interestingly, an association of the MITF mutation with coexisting melanoma and renal cell carcinoma was also shown. Collectively, these data suggest that MITF has an important oncogenic function in tumorigenesis of multiple tissues/melanocytes and kidney cells.

Melanoma: from melanocyte to genetic alterations and clinical options

Metastatic melanoma remained for decades without any effective treatment and was thus considered as a paradigm of cancer resistance. Recent progress with understanding of the molecular mechanisms underlying melanoma initiation and progression revealed that melanomas are genetically and phenotypically heterogeneous tumors. This recent progress has allowed for the development of treatment able to improve for the first time the overall disease-free survival of metastatic melanoma patients. However, clinical responses are still either too transient or limited to restricted patient subsets. The complete cure of metastatic melanoma therefore remains a challenge in the clinic. This review aims to present the recent knowledge and discoveries of the molecular mechanisms involved in melanoma pathogenesis and their exploitation into clinic that have recently facilitated bench to bedside advances.

A kinase-independent function of CDK6 links the cell cycle to tumor angiogenesis

In contrast to its close homolog CDK4, the cell cycle kinase CDK6 is expressed at high levels in lymphoid malignancies. In a model for p185BCR-ABL+ B-acute lymphoid leukemia, we show that CDK6 is part of a transcription complex that induces the expression of the tumor suppressor p16INK4a and the pro-angiogenic factor VEGF-A. This function is independent of CDK6's kinase activity. High CDK6 expression thus suppresses proliferation by upregulating p16INK4a, providing an internal safeguard. However, in the absence of p16INK4a, CDK6 can exert its full tumor-promoting function by enhancing proliferation and stimulating angiogenesis. The finding that CDK6 connects cell-cycle progression to angiogenesis confirms CDK6's central role in hematopoietic malignancies and could underlie the selection pressure to upregulate CDK6 and silence p16INK4a.

Novel germline CDK4 mutations in patients with head and neck cancer

BACKGROUND

Cyclin-dependent kinase 4 (CDK4) together with its regulatory subunit cyclin D1, governs cell cycle progression through G1 phase. Cyclin-dependent kinase inhibitors, including p16INK4A in turn regulate CDK4. In particular, deregulation of the p16/CDK4/cyclin D1 complex has been established in a variety of human tumors including gliomas, sarcomas, melanoma, breast and colorectal cancer. However, changes in CDK4 have rarely been observed.

METHOD

In this study we used a combination of PCR-SSCP and direct sequencing for mutational screening of CDK4. DNA was isolated from peripheral blood leukocyte of patients with squamous cell carcinoma of head and neck, for screening germline mutations in coding regions of CDK4.

RESULTS

Variations observed in exon 2 and 5 were three missense mutations, g5051G > C (Ser52Thr), g5095G > C (Glu67Gln), g5906C > A, g5907C > G (Pro194Ser) and novel frame shift mutations g7321_23delTGA, g7121_7122insG, g7143delG in exon 7 and 3'UTR respectively.

CONCLUSION

In conclusion, two novel mutations were found in N terminal domain which indicates that CDK4 mutation may play a major role in the development and progression of squamous cell carcinoma of head and neck.

Genetics of primary intraocular tumors

Primary intraocular neoplasms are tumors that originate within the eye. The most common malignant primary intraocular tumor in adults is uveal melanoma and the second is primary intraocular lymphoma or vitreoretinal (intraocular) lymphoma. The most common malignant intraocular tumor in children is retinoblastoma. Genetics plays a vital role in the diagnosis and detection of ocular tumors. In uveal melanoma, monosomy 3 is the most common genetic alteration and somatic mutations of BAP1, a tumor suppressor gene, have been reported in nearly 50% of primary uveal melanomas. The retinoblastoma gene RB1 is the prototype tumor suppressor gene-mutations in RB1 alleles lead to inactivated RB protein and the development of retinoblastoma. Immunoglobulin heavy chain (IgH) or T-cell receptor (TCR) gene rearrangement is observed in B-cell or T-cell primary vitreoretinal lymphoma, respectively. Other factors related to the genetics of these three common malignancies in the eye are discussed and reviewed.

CDKN2A mutations in melanoma families from Uruguay

BACKGROUND

Familial melanoma, a cluster of several cases within a single family, accounts for approximately 10% of cases of melanoma. Hereditary melanoma is defined as two or more first-degree relatives having melanoma. A member of a melanoma-prone family has a 35-70-fold increased relative risk of developing a melanoma. Genetic susceptibility is linked to the major susceptibility genes CDKN2A and CDK4, and the minor susceptibility gene MC1R.

OBJECTIVES

To determine the clinical and genetic characteristics of cutaneous melanoma in melanoma-prone families from Uruguay.

METHODS

We studied 13 individuals from six melanoma-prone families living in Uruguay. Phenotype, familial and personal history were recorded. Molecular screening of CDKN2A and CDK4 was done by polymerase chain reaction-single strand conformational polymorphism analysis. The MC1R gene was sequenced.

RESULTS

Mutations in CDKN2A were detected in five of six families: c.-34G>T, p.G101W and p.E88X. A novel germline mutation p.E88X, associated with hereditary melanoma in two unrelated families, is described. We hypothesize that a founder effect occurred probably in the Mediterranean region. No mutations in CDK4 were detected. Six different MC1R variants, all previously reported, were present in Uruguayan families.

CONCLUSIONS

The overall rate of deleterious CDKN2A mutations in our familial melanoma pedigrees, even though the sample size is small, was considerably higher (83%) than the often quoted range.

Clinical and Molecular Characterization of Patients at Risk for Hereditary Melanoma in Southern Brazil

Melanoma is the most dangerous of all common skin cancers, due to its propensity to metastasize. Therefore, identification of at-risk populations may allow early detection of disease at a curable stage. In Europe and North America, between 8-14% of melanoma patients have a family history of the disease, and a subset of these individuals possess germline mutations in the CDKN2A gene, which encodes the p16(INK4A) and p14(ARF) tumor suppressors. We identified 30 patients (29 families) from Southern Brazil, who had a family history of melanoma and/or pancreatic cancer; or a personal history of multiple primary melanoma. We screened this cohort for mutations in the CDKN2A and CDK4 genes, and detected two functional mutations: a G-34T transversion in 5'untranslated region; and a M53I alteration encoded in exon 2. Both mutants have been previously associated with melanoma and demonstrate founder effects. We conclude that germline mutations of CDKN2A occur in the Brazilian population, and that these mutations likely originated in Europe.

Do sex and site matter? Different age distribution in melanoma of the trunk among Swedish men and women

BACKGROUND

Recent research on cutaneous malignant melanoma (CMM) points to the coexistence of several biological pathways linked to the anatomical site of the lesion, which could lead to this neoplasm. Although the different anatomical distribution of CMM by sex is usually attributed to gender-specific patterns of sun exposure, it has been suggested that an alternative explanation might lie in gender-specific site susceptibility.

OBJECTIVES

This paper aimed at analysing the age distribution of CMM by site and sex to gain in-depth knowledge of differences between the sexes.

METHODS

Using a large Swedish cohort comprising 2 992 166 workers, Poisson models were fitted to estimate age-specific incidence rates by site and sex, duly adjusted for several factors that might account for changes in environmental exposures (period, birth cohort, socioeconomic level, latitude and rurality).

RESULTS

Incidence rates were 17.4 cases per 100 000 person-years in men and 16.5 in women. Sex differences were particularly striking for CMM of the trunk, where both crude and adjusted incidence rates displayed a steady increase with age in men, but reached a plateau in women at around four cases per 100 000 person-years from the 40-45-year age group (perimenopausal period) upwards. There was an almost fivefold increase in the sex ratio for this body site between the younger and older age groups, a difference which could not be attributed to period or cohort effects.

CONCLUSIONS

If different aetiological pathways can be assumed to lead to melanoma, then disparities between men and women, particularly in CMM of the trunk, suggest that a possible interaction between site and sex should be borne in mind.

The effect of the sun on expression of beta-catenin, p16 and cyclin d1 proteins in melanocytic lesions

BACKGROUND

The tumour suppressor gene product, p16, is often inactivated during melanoma malignant progression. Although the importance of p16 in melanomas is well documented, its relationship with cyclin D1, beta-catenin and ultraviolet radiation (UVR) remains unclear.

AIM

To determine the role of these cell cycle-related proteins and high-risk sun exposure in the biological behaviour of melanocytic lesions.

METHODS

We used immunohistochemistry to examine 28 melanocytic naevi (MN; 9 congenital and 19 acquired types) and 24 primary cutaneous malignant melanomas (CMM; 19 nodular melanomas, 3 lentigo maligna melanomas, 1 acral lentiginous melanoma and 1 superficial spreading melanoma) for the presence of p16, cyclin D1 and beta-catenin. The melanocytic lesions were classified into two groups to examine the effects of UVR on these three proteins: high risk of sun exposure (chronically sun damaged; CSD), or low risk of sun exposure (nonchronically sun damaged; non-CSD). We evaluated the relationship between the production of these proteins and the histopathological and clinical characteristics of the lesions.

RESULTS

Production of p16 was repressed in most CMM, but not in MN (P < 0.0001). Cyclin D1 was overproduced in CMM but not in MN, and beta-catenin was frequently overproduced both in MN and CMM. Overproduction of beta-catenin was not common in CSD melanocytic lesions, but was more frequent in non-CSD melanocytic lesions (P = 0.027).

CONCLUSION

An immunohistochemical panel including melanocytic markers enriched by p16 and cyclin D1 could be used to differentiate some borderline melanocytic lesions. In addition, the Wnt/beta-catenin pathway was more frequently activated in non-CSD than in CSD melanocytic lesions.

Cutaneous phenotype and MC1R variants as modifying factors for the development of melanoma in CDKN2A G101W mutation carriers from 4 countries

The G101W founder mutation is the most common CDKN2A mutation in Italy, Spain, and France. As the background of modifying genes, environmental exposures, and sun behavior vary across countries, studying G101W carriers from distinct countries offers a unique opportunity to evaluate possible modifying factors in melanoma development. We evaluated 76 G101W cases and 59 carrier controls from France, Italy, Spain, and the United States. Hair color and dysplastic nevi distributions differed significantly in cases and controls across the 4 study groups. Cases also varied significantly for eye color, freckling, and nevi. The distribution of MC1R variants in cases differed significantly across study groups because 12% of Italian melanoma patients had > or =2 MC1R variants vs. >50% for the other case groups. Several MC1R covariates showed significant associations with melanoma risk in all groups combined and in the American, French, and Spanish samples; no significant findings were observed in the Italian sample. In multiple-case families, the number and type of MC1R variants varied significantly between multiple-primary-melanoma and single-primary-melanoma patients from the 4 groups; there was also a significant decrease in median age at melanoma diagnosis as the number or type of MC1R variants increased. The variation in the effects of the cutaneous phenotypic and MC1R factors across the study sample suggests that these factors differentially contribute to development of melanoma even on a common genetic background of a germline CDKN2A mutation. Differences in melanoma risk across geographic regions justify the need for individual studies in each country before counseling should be considered.

Does melanoma behave differently in younger children than in adults? A retrospective study of 33 cases of childhood melanoma from a single institution

OBJECTIVE

To ascertain whether childhood melanoma presents any peculiar clinical features or differences in prognosis with respect to adults, we retrospectively analyzed the data from 33 patients who were up to 14 years of age and treated for cutaneous melanoma at the Istituto Nazionale Tumori, Milan, over a 25-year period.

METHODS

Primary lesions were amelanotic in half of the cases and raised in 73%. Lower extremities were the most common primary sites. Histologically, 9 cases were classified as nodular type, and median thickness was 2.5 mm. Nine children had nodal involvement at diagnosis, 2 in-transit metastases, and 1 distant spread. Surgery was the mainstay of treatment; 9 patients underwent lymph node dissection, 3 received chemotherapy, and 2 received radiotherapy.

RESULTS

With a median follow-up of 122 months, 5-year event-free survival and overall survival were 60% and 70%, respectively. Age seemed to correlate with survival, event-free survival being 90% in children under 10 and 47% in older patients, although the initial microstaging seemed worse in the former.

CONCLUSION

By comparison with adult cases, childhood melanoma can have a higher percentage of atypical clinical features (amelanotic and raised lesions), nodular histotype, and thick lesions. Although we have no data to support any suggestion of biological differences between young children and adolescents or adults, our findings give the impression that melanoma behaves differently in the younger age group.

Familial malignant melanoma - overview

Approximately 3-15% of all malignant melanomas (MM) are familial cases. MM is a highly heterogeneous tumour type from a genetic perspective. Pedigrees with disease confined to a single generation of siblings or MM occurring among second- or third-degree relatives suggest multifactorial polygenic inheritance. However, not infrequently, within large families aggregations of MM are consistent with autosomal dominant inheritance, suggesting a hereditary syndrome caused by germline alterations of a single gene. Several different genes are involved in the development of MM. However, even when taken together they are responsible for less than 20% of all MM cases. It is thus necessary to perform association studies focused on genetic markers that could be used in identifying patients with a high risk of MM. Evaluation of aggregations of MM and other malignancies, like breast cancer, could be essential in identifying relatives of MM probands being at high risk of developing malignancies other than MM. The ultimate goal is to apply in these cases prevention recommendations and surveillance protocols to reduce the disease risk.

Cutaneous melanoma: hints from occupational risks by anatomic site in Swedish men

AIMS

To improve knowledge of the epidemiology of melanoma by comparing occupational risks of cutaneous melanoma (CM) by anatomic site in Swedish workers.

METHODS

Male workers employed in 1970 and living in the country in 1960 were followed up from 1971 to 1989 using the Swedish Registers of Death and Cancer. A more specifically exposed subcohort included men reporting the same occupation in 1960 and 1970. For each location, occupational risk ratios (RRs) were extracted from Poisson regression models adjusted by age, period, town size, and geographical area. To diminish the influence of socioeconomic factors, intrasector analyses, comparing only jobs belonging to the same occupational sector, were performed. Risk patterns for different locations were compared.

RESULTS

High RRs for different sites were found among workers exposed to UV sources (dentists, physiotherapists, and lithographers), and sun exposed workers (harbour masters, and lighthouse/related work). Risk excesses were seen in fur tailors, tanners/fur dressers, patternmakers/cutters, electrical fitters/wiremen, telephone/telegraph installers/repairmen, and some glass/pottery/tile workers. Results for lower and upper limbs were significantly correlated but somewhat independent of those found in thorax, the most frequent location. Correlation between head/neck and thorax was moderate. Specific risk excesses were found for rolling mill workers in head/neck, for chimney sweeps in upper limbs, and for aircraft pilots/navigators/flight engineers in lower limbs.

CONCLUSIONS

High RRs in the trunk among occupations with UV exposure from artificial sources suggest an effect not restricted to exposed sites. An unusual distribution of cases and RRs in chimney sweeps, rolling-mill, or glass/pottery/tile workers suggests local effects of exposures. The not previously reported risk excess in this job and in fur related processes, and the RR in electrical fitters and telephone/telegraph installers deserve further investigation. Disparities between locations, as RRs in thorax and limbs, may reflect differences in aetiological mechanisms.

Melanoma hereditário: prevalência de fatores de risco em um grupo de pacientes no Sul do Brasil

FUNDAMENTOS: Aproximadamente 10% dos casos de melanoma são atribuíveis a mutações em genes de predisposição, sendo, portanto, hereditários. OBJETIVOS: Este estudo avalia a prevalência de fatores de risco para melanoma hereditário em um grupo de pacientes com melanoma no sul do Brasil. CASUÍSTICA E MÉTODOS: Foram estudados 195 pacientes com diagnóstico de melanoma admitidos consecutivamente no Hospital de Clínicas de Porto Alegre entre janeiro de 1999 e junho de 2000. RESULTADOS: A idade média ao diagnóstico de melanoma foi de 48 anos em homens e 44,9 anos em mulheres. Dos 133 pacientes cuja história familiar encontrava-se registrada no prontuário, 13 (9,8%) apresentavam história familiar de melanoma. A presença de ao menos um fator de risco importante para predisposição hereditária ao melanoma foi constatada em 31 pacientes (16%; IC 95% 10,9% - 21,1%). CONCLUSÃO: A possibilidade de influência do fator hereditário no Brasil estimula a procura ativa de fatores de risco genético em pacientes com melanoma, já que a identificação de famílias de alto risco pode ter grande impacto sobre a morbimortalidade de seus integrantes.

p53 Codon 72 Arg Homozygotes Are Associated with an Increased Risk of Cutaneous Melanoma

The p53 gene plays an important role in cell cycle control, facilitating DNA repair activities in response to DNA damage. Aberrant cell cycle control impairs DNA repair and increases the probability of mutations that can lead to carcinogenesis. The p53 gene is polymorphic at codon 72 (Arg/Pro) of its protein, which is functionally distinct, leading to inquiry into its role in carcinogenesis. In this hospital-based case-control study of 289 newly diagnosed patients with melanoma and 308 cancer-free control subjects, we evaluated whether the p53 codon 72 variant is associated with risk of cutaneous melanoma (CM). The controls were frequency-matched to the cases by age, sex, and ethnicity. The frequency of the p53 Arg allele was 78.2% in cases and 73.2% in controls (p=0.045), and the genotype frequencies of p53 Arg/Arg, Arg/Pro, and Pro/Pro were 62.6%, 31.1%, and 6.3%, respectively, in the cases, and 53.9%, 38.6%, and 7.5%, respectively, in the controls (p=0.096). Logistic regression analysis revealed that the p53 Arg/Arg genotype was associated with a significantly increased risk of melanoma (adjusted odds ratio (OR)=1.43; 95% confidence interval (CI)=1.02-2.02) compared with other genotypes, and this association was more evident in subgroups of older subjects (OR=2.32; 95% CI=1.39-388), and subjects with Fitzpatrick's skin type III or IV (OR=1.69; 95% CI=1.11-2.59). In conclusion, this study found some evidence that in subjects over 50, p53 Arg/Arg genotype is associated with increased risk of CM as compared to genotypes Arg/Pro or Pro/Pro. Further larger studies are needed to substantiate our findings.

CDKN2A as a uveal and cutaneous melanoma susceptibility gene

A few families have been described whose members are affected by either cutaneous melanoma (CM) or uveal melanoma (UM), suggesting that a common susceptibility could exist. Although CDKN2A is the main CM predisposing gene, thus far no germline CDKN2A mutations have been described in families with both CM and UM. We report a Gly67Ser missense CDKN2A germline mutation in a melanoma-prone family, where one carrier was affected by UM and the other by a CM. Immunohistochemistry performed on the UM tissue block revealed loss of CDKN2A protein staining in tumor cells. These observations demonstrate that CDKN2A is also a UM susceptibility gene.

Biomarkers in melanoma: predisposition, screening and diagnosis

Melanoma's incidence and mortality for certain groups has appeared to level off after a steady increase over the last half century. This trend is suspected to be due to better detection and removal of thin, biological early melanomas. However, to date, no prospective evidence exists to clearly demonstrate the efficacy of prevention and early detection in decreasing melanoma mortlity. Nonetheless, many studies suggest that both self-assessment of risk factors or clinician examination can identify a proportion of patients at highest risk for melanoma who may benefit from behavior modification (primary prevention) and routine screening (secondary prevention). Compromising these goals is the fact that neither the clinical or histologic diagnosis of melanoma is 100% accurate. Clinical diagnosis of melanoma, based on evaluation of a skin lesion's color and shape, correlates best with the experience of the clinician. Ancillary technologies have been developed to improve clinical accuracy of suspicious skin lesions but a subset of melanomas exist that do not fall in the spectrum of the 'ABCDE' guidelines commonly used for melanoma identification. Similarly, at the histologic level (the 'gold standard' of diagnosis), overlap exists between benign and malignant melanocytic proliferations leading to both over and underdiagnosis of melanoma. A better understanding of melanoma's pathogenesis has identified disease-related biomarkers that may more reliably differentiate a melanocytic nevus from melanoma. In this paper, we review current and novel, potentially more accurate, biomarkers and supplementary technologies that can be used for the prevention, screening and diagnosis of melanoma.