Distribution of MC1R variants among melanoma subtypes: p.R163Q is associated with lentigo maligna melanoma in a Mediterranean population

BACKGROUND

Cutaneous melanoma tumour is classified into clinicohistopathological subtypes that may be associated with different genetic and host factors. Variation in the MC1R gene is one of the main factors of risk variation in sporadic melanoma. The relationship between MC1R variants and the risk of developing a specific subtype of melanoma has not been previously explored.

OBJECTIVES

To analyse whether certain MC1R variants are associated with particular melanoma subtypes with specific clinicohistopathological features.

METHODS

An association study was performed between MC1R gene variants and clinicopathological subtypes of primary melanoma derived from 1679 patients.

RESULTS

We detected 53 MC1R variants (11 synonymous and 42 nonsynonymous). Recurrent nonsynonymous variants were p.V60L (30·0%), p.V92M (11·7%), p.D294H (9·4%), p.R151C (8·8%), p.R160W (6·2%), p.R163Q (4·2%) p.R142H (3·3%), p.I155T (3·8%), p.V122M (1·5%) and p.D84E (1·0%). Melanoma subtypes showed differences in the total number of MC1R variants (P = 0·028) and the number of red hair colour variants (P = 0·035). Furthermore, an association between p.R163Q and lentigo maligna melanoma was detected under a dominant model of heritance (odds ratio 2·16, 95% confidence interval 1·07-4·37; P = 0·044). No association was found between p.R163Q and Fitzpatrick skin phototype, eye colour or skin colour, indicating that the association was independent of the role of MC1R in pigmentation. No association was observed between MC1R polymorphisms and other melanoma subtypes.

CONCLUSIONS

Our findings suggest that certain MC1R variants could increase melanoma risk due to their impact on pathways other than pigmentation, and may therefore be linked to specific melanoma subtypes.

Comparison between familial and sporadic cutaneous melanoma in Valencia, Spain

Some clinical, pathological and genetic features have been associated to familial melanoma, particularly multiple melanoma and earlier age at diagnosis. To compare the clinical, epidemiological and pathological differences between familial and sporadic melanoma patients in Valencia, Spain, a series of 959 patients with cutaneous melanoma were selected at a single institution. For this study the following variables were selected: age, sex, melanoma site and presence of solar lentigines on the melanoma surrounding skin, histological subtype, tumor thickness, stage, family and personal history of cutaneous melanoma and of other neoplasias, personal history of non-melanoma skin cancer, past personal history of severe sunburns, cutaneous phenotype (phototype, hair and eyes colors number of common nevus, number of atypical nevi, presence of solar lentigines). Forty-one (4.28%) familial and 918 sporadic melanoma were identified. Among the multiple variables studied, a younger age at diagnosis (median age of 42 vs 53 years), higher frequency of the presence of at least one clinically atypical nevus (36.1% vs 17.7%), multiple melanomas (12.2% vs 3.4%) and red/blonde hair (33.3% vs 18.9%), and a lower rate of cases with solar lentigines in melanoma site (33.3% vs 56.3%) were found for familial cases. Except for hair color and age, the other variables remained statistically significant after the multivariate study. Interestingly, no acral melanomas were found among the familial cases. In summary, phenotypic risk factors for familial melanoma are a tendency to develop multiple melanomas, to have clinically atypical nevi and to present less actinic damage at the melanoma site. All these results enhance the relevancy of genetic susceptibility associated to the ability to produce atypical nevi and partly to a higher sensitivity to the sun.

Corroboration of polymorphisms in the aromatase (CYP19A1) gene with response to neoadjuvant therapy with letrozole in postmenopausal women with stages II-II ER/PgR-positive breast cancer

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Background: Aromatase (CYP19A1) is the main enzyme implicated in estrogen biosynthesis. Polymorphisms in CYP19A1 can affect both aromatase expression and activity leading to changes in the estrogen levels. These changes have been previously associated with pathogenesis of estrogen-dependent diseases, including breast cancer. The purpose of this study is to evaluate whether the genotype of CYP19A1 can have an effect on the response to endocrine therapy with the aromatase inhibitor letrozole (L). Methods: We retrospectively analyzed a series of 58 postmenopausal women with stage II-III ER/PgR[+] breast cancer treated with L as neoadjuvant therapy. Response was evaluated by radiology (mammogram or ultrasound) at four months L (OMS) and data was available in 56 cases. A total of ten single nucleotide polymorphisms (SNPs) spanning the gene, a TCT insertion/deletion and a (TTTA)n repeat were evaluated. The (TTTA)n repeat was analyzed by using GeneScan to detect polymorphism length, TCT Ins/Del by direct sequencing and SNPs by allelic discrimination using TaqMan SNP Genotyping Assays (Applied Biosystems). Logistic regression analysis was used to estimate the most accurate predictive model for response to therapy. Results: Median age of our series was 77 years (range: 68 to 90). Twenty women (36%) responded to 4 months L, while 38 (67%) did not (2 PD and 36 EE). Allelic frequencies were determined for each polymorphism and the global genotype data was evaluated in a logistic regression analysis. In a first step, the analysis with the genetic information for the 12 polymorphisms resulted in a model that predicted radiological response to L with an accuracy of 80% (85% specifity, 69% sensibility). However, a reduction to 4 informative polymorphisms generated a simpler predictive model with an accuracy of 76% (76.5% specifity, 75% sensibility). Conclusions: Polymorphism analysis of CYP19A1 could predict for response to neoadjuvant therapy with L. A validation of this predictive model in an independent series is ongoing.

No significant financial relationships to disclose.