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

Summary 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.