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 anti gen (HLA)-restricted manner. Although expression of MAGE genes has been stu died in cutaneous MMs, little is known about their expression in melanocyti c naevi. We studied MAGE 1, 2, 3, 4, 6 and 12 gene expression in tissue fro m 10 benign melanocytic naevi. 14 dysplastic melanocytic naevi, three cutan eous MMs in situ, four primary cutaneous MMs and three distant metastatic M Ms. MAGE gene expression was determined with reverse transcription-polymera se chain reaction (PCR) using random hexamers to generate cDNA from total t issue homogenate RNA followed by PCR using intron-spanning, MAGE-specific p rimer pairs. Controls were cDNA from MAGE-expressing melanoma cell lines. E xpression of HLA class 1 was used as a cDNA quality control. MAGE 2, 4, 6 a nd 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 express ed 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.