Meccanismi determinanti instability genomica nei tumori melanocitari e non

Melanoma is one of the highest grade malignant tumour. Environmental factors and genetic mechanisms cause tumour onset and progression. On the basis of genomic damage, cell induces the DNA Repair System or the programmed cell death (apoptosis). In the DNA repair system, the "Mismatch Repair" corrects non-complementary DNA sequences and neutralizes recombination processes between homologue DNA sequences. Genetic alterations, observed in gastrointestinal (G.L) tumours, reflect the presence of genomic instability induced by the high frequency of repeat sequences, known as microsatellite. Microsatellite instability (MSI) represent an epiphenomenon of pathogenic mechanisms of G.I. tumours. Genomic mutations are extremely variable in melanocytic tumours. Through microsatellite analysis, we studied genomic instability in cutaneous melanoma, in which MSI grade and role is not completely known. Our results showed: a) no mutations in mononucleotide repeat sequences, that are present in dinucleotide sequence; b) alterations in trinucleotide repeat sequences. These data suggest that (a) there is a different microsatellite instability pattern in cutaneous melanoma than in gastrointestinal tumours; b) the mechanisms inducing genomic instability in trinucleotide sequences may play an important role in oncogenesis and tumour progression of melanocytic tumours.