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DNA methylation analysis by DREAM of UV irradiated melanocytes

ABSTRACT: Ultraviolet radiation (UVR) is the greatest risk factor for melanoma development. While the role of UVR in DNA mutagenesis is generally accepted, the role of UVR-induced mutations in melanomagenesis remains controversial. To understand better how UVR is contributing to melanoma development, we investigated the non-mutational effect of UVR on the epigenome, specifically DNA methylation. Aberrant DNA methylation changes are a hallmark in melanoma and there are few reports on the effects of UVR on DNA methylation. We exposed melanocytes to UVR and cultured them for one-month to detect heritable and stable changes in DNA methylation. We found both hyper and hypo methylated sites after UVR exposure. While many of these changes occurred outside of promoters and areas of active gene expression, there were changes in promoter DNA methylation changes that correlated with changes in gene expression. These changes also correlated with those found in melanoma and UVR sensitive sites were prognostic of patient overall survival. Our work shows UVR-induced DNA methylation changes in melanocytes and may be a novel non-mutational mechanism in which UVR contributes to melanoma development.

ORGANISM(S): Mus musculus Homo sapiens

PROVIDER: GSE169695 | GEO | 2024/03/25

REPOSITORIES: GEO

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Project description:Melanoma is the deadliest form of skin cancer with rising incidence and mortality rates. Oncogenic mutation in BRAF gene is the single most frequent genetic alteration in human melanoma; however, this event per se is not sufficient to produce melanoma in vivo. We have investigated whether epigenetic changes, specifically aberrant DNA methylation and dysregulation of gene expression, alone or in combination with this genetic event, are involved in the genesis of human melanoma. We have constructed the whole M-bM-^@M-^XM-bM-^@M-^Xof primary human melanomas in relation to their BRAF mutational status. Our methylation profiling identified a large number of hyper- or hypomethylated genes in melanoma tumors, many of which being novel and having the potential to serve as biomarkers. Gene ontology analysis revealed that gene categories involved in neuronal cell morphology and development, and skin and neurological disorders were highly enriched. Frequently methylated targets included developmental regulatory transcription factors and homeobox genes, which are mostly subjected to bivalent histone marking and Polycomb occupancy in embryonic stem cells. Notably, several genes involved in the MEK-ERK and the PI3K pathways, two of the most frequently perturbed pathways in human melanoma, showed extensive methylation changes. Gene expression profiling identified a long list of dysregulated genes, many of which being involved in melanocytes development and differentiation, and showing concomitant aberrant DNA methylation. Sub-typing of the melanoma tumors based on BRAF mutational status revealed that tumors with a mutated BRAF had distinctive and more pronounced changes in both DNA methylation and gene expression profiles than tumors carrying the wildtype BRAF. The differentially compromised methylome and transcriptome of melanomas (dependent on BRAF mutation) deserves special attention because many epigenetic alterations, including DNA methylation-mediated regulation of gene expression, are potentially reversible. The dichotomous integrity of epigenome in human melanoma holds great promise for the field of personalized medicine. Methylome: Eleven primary human melanoma speciemens versus five normal human melanocyte samples. Transcriptome: Ten primary human melanoma speciemens versus four normal human melanocyte samples

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DNA methylation analysis by DREAM of UV irradiated melanocytes

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