Frequent Occurrence of NRAS and BRAF Mutations in Human Acral Naevi

Genetic and methylation profiles distinguish benign, malignant and spitzoid melanocytic tumors

Accurate classification of melanocytic tumors is important for prognostic evaluation, treatment and follow-up protocols of patients. The majority of melanocytic proliferations can be classified solely based on clinical and pathological criteria, however in select cases a definitive diagnostic assessment remains challenging and additional diagnostic biomarkers would be advantageous. We analyzed melanomas, nevi, Spitz nevi and atypical spitzoid tumors using parallel sequencing (exons of 611 genes and 507 gene translocation analysis) and methylation arrays (850k Illumina EPIC). By combining detailed genetic and epigenetic analysis with reference-based and reference-free DNA methylome deconvolution we compared Spitz nevi to nevi and melanoma and assessed the potential for these methods in classifying challenging spitzoid tumors. Results were correlated with clinical and histologic features. Spitz nevi were found to cluster independently of nevi and melanoma and demonstrated a different mutation profile. Multiple copy number alterations and TERT promoter mutations were identified only in melanomas. Genome-wide methylation in Spitz nevi was comparable to benign nevi while the Leukocytes UnMethylation for Purity (LUMP) algorithm in Spitz nevi was comparable to melanoma. Histologically difficult to classify Spitz tumor cases were assessed which, based on methylation arrays, clustered between Spitz nevi and melanoma and in terms of genetic profile or copy number variations demonstrated worrisome features suggesting a malignant neoplasm. Comprehensive sequencing and methylation analysis verify Spitz nevi as an independent melanocytic entity distinct from both nevi and melanoma. Combined genetic and methylation assays can offer additional insights in diagnosing difficult to classify Spitzoid tumors.

PTEN as a target in melanoma

PTEN is a well-known tumour suppressor protein that is frequently found to be mutated, inactivated or deleted in a wide range of different cancers. Its tumour suppressive properties result predominantly from its inhibitory effects on the PI3K-AKT signalling pathway. In melanoma, numerous different PTEN mutations have been identified in both melanoma cell lines and melanoma tissue. A number of different molecules can act on PTEN to either promote its suppression of melanoma, while other molecules may antagonise PTEN to inhibit its mechanism of action against melanoma. This review will discuss how the interactions of PTEN with other molecules may have a positive or negative impact on melanoma pathogenesis, giving rise to the potential for PTEN-targeted therapies against melanoma.

Skin cancer biology and barriers to treatment: Recent applications of polymeric micro/nanostructures

Background

Skin cancer has been the leading type of cancer worldwide. Melanoma and non-melanoma skin cancers are now the most common types of skin cancer that have been reached to epidemic proportion. Based on the rapid prevalence of skin cancers, and lack of efficient drug delivery systems, it is essential to surge the possible ways to prevent or cure the disease.

Aim of review

Although surgical modalities and therapies have been made great progress in recent years, however, there is still an urgent need to alleviate its increased burden. Hence, understanding the precise pathophysiological signaling mechanisms and all other factors of such skin insults will be beneficial for the development of more efficient therapies.

Key scientific concepts of review

In this review, we explained new understandings about onset and development of skin cancer and described its management via polymeric micro/nano carriers-based therapies, highlighting the current key bottlenecks and future prospective in this field. In therapeutic drug/gene delivery approaches, polymeric carriers-based system is the most promising strategy. This review discusses that how polymers have successfully been exploited for development of micro/nanosized systems for efficient delivery of anticancer genes and drugs overcoming all the barriers and limitations associated with available conventional therapies. In addition to drug/gene delivery, intelligent polymeric nanocarriers platforms have also been established for combination anticancer therapies including photodynamic and photothermal, and for theranostic applications. This portfolio of latest approaches could promote the blooming growth of research and their clinical availability.

Novel genetic alteration in congenital melanocytic nevus: MAP2K1 germline mutation with BRAF somatic mutation

Congenital melanocytic nevus (CMN) represent a benign proliferative skin disease in the epidermis and dermis. CMN are historically known to be associated with activating NRAS or BRAF mutations. Melanoma frequently harbors the BRAF p.Val600Glu mutation, which is also commonly found in benign nevi. A recent study reported mutation of MAP2K1, a downstream effector of the RAS-RAF-MEK pathway, in melanoma with an overall frequency of 8%. Later, in 2019, Jansen P detected one activating MAP2K1 mutation in acral nevi. However, it is unknown whether MAP2K1 mutations are common in CMN, and how MAP2K1 contributes to the pathogenesis of CMN remains to be determined.In this study, we report one patient clinically and histologically diagnosed with CMN, with the MAP2K1 germline mutation and a BRAF p.Val600Glu somatic hit in the lesion. To the best of our knowledge, this is the first report of the coexistence of mutated BRAF and MAP2K1 in CMN, which may suggest that MAP2K1 mutations contribute to the occurrence and development of nevus expanding our knowledge of the genetics of CMN.

Targeted next generation sequencing (NGS) to classify melanocytic neoplasms

This study piloted a pan-solid-tumor next generation sequence (NGS)-based laboratory developed test as a diagnostic aid in melanocytic tumors. 31 cases (4 "epithelioid" nevi, 5 blue nevi variants, 7 Spitz tumors [3 benign and 4 malignant] and 15 melanomas) were evaluated. All tumors [median diameter 7 mm (range 4-15 mm); median thickness 2.25 mm (range 0.25-12 mm)] yielded satisfactory results. The number of small nucleotide variants/tumor was significantly different between melanoma (median 18/tumor, range 4-71) and all other lesions (median 8/tumor, range 3-17) (P < 0.004) and malignant (median 16/tumor, range 4-71) vs benign lesions (median 7/tumor, range 3-14) (P = 0.01). BRAF, MET, NTRK1, and ROS fusions only occurred in benign Spitz tumors; EML4 fusion, BRAF, MAP2K1 and TERT mutations occurred in malignant Spitz tumors and/or melanoma. Amplifications and NRAS and NF1 mutations only occurred in melanoma. Most melanomas contained >1 pathogenic alteration. Developed NGS-based criteria correctly classified all malignant lesions in this series. 10/12 cases showed concordance with FISH; consensus diagnosis agreed with NGS classification in FISH-non-concordant cases. This pilot study suggests that NGS may be an effective diagnostic adjunct comparable to FISH, but further studies with larger numbers of cases are needed.

Giant congenital melanocytic nevus of the scalp: from clinical-histological to molecular diagnosis

Congenital melanocytic nevus (CMN) is a benign proliferative skin disease in the epidermis and dermis. Large to giant CMNs are estimated to be associated with an increased lifetime risk of malignancy. It is necessary to estimate and monitor the risk of malignant transformation for giant CMNs. To date, the clinical “ABCD” criteria and immunohistochemistry studies can be confusing and, to some extent, subjective. Accordingly, the elucidation of genomic analyses of nevi is required to better understand the malignant transformation of CMNs. Here, we describe two large to giant CMNs of the scalp with opposite clinical-histological and molecular evaluations of potential malignancy risk. To our knowledge, this is the first description of a genetic study of large to giant CMNs of the scalp in East Asia. We recommend reviewing the molecular diagnosis together with careful medical history and histological information to facilitate the evaluation of the potential malignancy risk.