Project description:Cutaneous, ocular and mucosal melanomas are histologically indistinguishable tumors that are driven by different spectrum of genetic alterations. With current methods, identification of the site of origin of a melanoma metastasis is challenging, in particular when the metastasis is the first tumor manifestation. Genome wide DNA methylation profiling has shown promise for the identification of the site of tumor origin in various settings. Here we explore the DNA methylation landscape of melanomas from different sites and analyze if different melanoma origins can be distinguished by their epigenetic profile. We performed DNA methylation analysis, next generation DNA panel sequencing and copy number analysis of 82 non-cutaneous and 25 cutaneous melanoma samples. We further analyzed eight normal melanocyte cell culture preparations by DNA methylation profiling. DNA methylation analysis clearly separated uveal melanomas from melanomas of other primary sites while mucosal, conjunctival and cutaneous melanomas were epigenetically almost identical. Still, we observed DNA methylation differences in cancer-related genes, such as low frequencies of RARB and CDKN2A promoter methylation in mucosal melanomas, while conjunctival melanomas frequently harbored APC promoter methylation. Furthermore, all investigated melanomas of the paranasal sinus showed loss of PTEN expression, mainly caused by promoter methylation. This was less frequently seen in melanomas of other sites. Copy number analysis revealed recurrent amplifications in mucosal melanomas, including chromosome 4q, 5p, 11q and 12q. Most melanomas of the oral cavity showed gains of chromosome 5p with TERT amplification while 11q amplifications were enriched in melanomas of the nasal cavity. Mucosal, conjunctival and cutaneous melanomas show a surprisingly similar DNA methylation profile and identification of the site of origin by DNA methylation testing is likely not feasible. Still, our study shows that there are DNA methylation differences on the gene level in known tumor drivers, related to the anatomical primary site.
Project description:Although identified as the key environmental driver of common cutaneous melanoma, the role of ultraviolet radiation (UVR)-induced DNA damage in mucosal melanoma is poorly defined. We present the largest cohort of mucosal melanomas of conjunctival origin to be analyzed by whole genome sequencing and show a predominance of UVR-associated single base substitution signature 7 (SBS7) in the majority of the samples. Our data shows mucosal melanomas with SBS7 dominance have similar genomic patterns to cutaneous melanomas and therefore this subset could benefit from treatments currently used for common cutaneous melanoma.
Project description:NanoString data on 12 conjunctival melanomas and mucosal melanoma The objective was to compare conjunctival melanoma with other mucosal melanomas at the RNA level using NanoString expression analysis of FFPE material.
Project description:<p>Mucosal melanoma is a deadly disease that carries the worst prognosis amongst subtypes of melanoma. Like all melanomas, mucosal melanomas are frequently driven by activating mutations in the MAPK and/or PI3K pathways; however, unlike melanomas that arise on sun-exposed skin, mucosal melanomas harbor few point mutations. Instead, most somatic alterations involve structural alterations, which appear early during tumor progression. Molecular studies in mucosal melanoma generally only profile point mutations without interrogating copy number alterations, and pathogenic mutations are only found in 30% of cases. We sequenced 38 mucosal melanomas, and in addition to profiling point mutations, we looked for copy number alterations that amplify oncogenes or delete tumor suppressors.</p>
Project description:We conducted whole genome sequencing of 5 mucosal melanomas and their matched DNA from blood. We conducted whole exome sequencing of a further 5 mucosal melanomas and their matched DNA from blood.