Melanoma antigen-encoding gene expression in melanocytic naevi and cutaneous malignant melanomas

Melanoma antigen-encoding (MAGE) genes encode peptides which are expressed by a proportion of malignant melanomas (MMs) and can be recognized in vitro by autologous cytolytic T lymphocytes in a human leucocyte-associated antigen (HLA)-restricted manner. Although expression of MAGE genes has been studied in cutaneous MMs, little is known about their expression in melanocytic naevi. We studied MAGE 1, 2, 3, 4, 6 and 12 gene expression in tissue from 10 benign melanocytic naevi, 14 dysplastic melanocytic naevi, three cutaneous MMs in situ, four primary cutaneous MMs and three distant metastatic MMs. MAGE gene expression was determined with reverse transcription-polymerase chain reaction (PCR) using random hexamers to generate cDNA from total tissue homogenate RNA followed by PCR using intron-spanning, MAGE-specific primer pairs. Controls were cDNA from MAGE-expressing melanoma cell lines. Expression of HLA class 1 was used as a cDNA quality control. MAGE 2, 4, 6 and 12 gene expression was not detected in any of the lesions studied. MAGE 1 and 3 gene expression was also not detected in any of the cases of benign and dysplastic melanocytic naevi and in situ MMs. One of four primary MMs expressed the MAGE 3 gene. Two of three distant metastatic MMs also expressed the MAGE 3 gene and one of these additionally expressed the MAGE 1 gene. Thus, MAGE gene expression appears to be a late event in the evolution of MMs.