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Genotypic and gene expression studies in Congenital Melanocytic Nevi: insight into initial step of tumoral melanogenesis

ABSTRACT: Large Congenital Melanocytic Naevi have a higher propensity to malignant transformation compared to acquired naevi. They thus represent a good model for studying initial steps of melanocarcinogenesis. We have performed genotypic (karyotype, FISH and mutational analyses) and differential expression studies on a large cohort of medium (n=3) and large (n=24) congenital melanocytic naevi. Unlike malignant melanoma, chromosomal abnormalities were rare and single, a feature probably reflecting the benignity of these lesions. Mutational screening showed a high frequency of NRAS mutations in our series, while BRAF mutations were less common. Differential expression study between tumoral and normal melanocytes did not show significant alterations of cellular processes such as cell proliferation, cell migration/invasion, angiogenesis, apoptosis, and immune/inflammatory responses. However, significant down-regulation of genes involved in pigmentation and up-regulation of genes playing a role in DNA protection were observed. Lastly, our micro-arrays displayed up-regulation of genes mediating chemoresistance in cancer. As alteration of pigmentation mechanisms can trigger oxidative damage, increased expression of genes involved in maintenance of DNA integrity might reflect the ability of naevocytic cells to self protection against cellular stress. Furthermore, the observed alterations linked to chemoresistance might partially account for the well known inefficacy of chemotherapy in malignant melanoma. Keywords: cell type comparison

ORGANISM(S): Homo sapiens

PROVIDER: GSE8525 | GEO | 2008/07/01

SECONDARY ACCESSION(S): PRJNA101651

REPOSITORIES: GEO

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