MYC gene numerical aberrations in actinic keratosis and cutaneous squamous cell carcinoma.

BACKGROUND: The genetic alterations that drive the transition from actinic keratoses (AKs) to cutaneous squamous cell carcinomas (SCCs) have not been defined precisely. Amplification and/or overexpression of the MYC proto-oncogene have been demonstrated in several human, malignant tumours including head and neck SCCs.

OBJECTIVES: To evaluate the presence of MYC genomic aberrations in both AKs and SCCs.

METHODS: Skin biopsy specimens corresponding to AKs, SCCs and control samples were included in two paraffin-embedded tissue microarrays. MYC cytogenetic profile was evaluated by fluorescence in situ hybridization (FISH). The results obtained were compared with MYC immunohistochemical expression.

RESULTS: Twenty-three AKs and 30 SCCs were evaluated. MYC numerical aberrations were observed in eight of 23 (35%) AKs and 19 of 30 (63%) SCCs (P = 0.05). MYC numerical aberrations were more frequent in moderately to poorly differentiated SCCs (77%) when compared with well-differentiated SCCs (25%; P = 0.027). A significant association between copy number gains of MYC by FISH analysis and MYC protein expression was demonstrated.

CONCLUSIONS: MYC gains and amplifications are frequent cytogenetic abnormalities in SCCs and may play a relevant role in promoting SCC undifferentiation and tumoral progression.