MAGE-12 and MAGE-6 are frequently expressed in malignant melanoma

MAGE proteins have been identified as potential specific targets for cancer vaccination. Although MAGE-6 and MAGE-12 were originally identified in mal ignant melanoma there are no studies reporting the frequency of expression of these antigens in this malignancy. These are of relevance particularly f or MAGE-6 as recent studies have identified CTL activity against several ep itopes. We have studied MAGE-1, -2, -3, -4, -6 and -12 gene expression usin g reverse transcription-polymerase chain reaction in 47 melanoma samples an d 11 melanoma cell lines established from these tumours. The tumour samples expressed MAGE-12 (74%) and MAGE-6 (64%) mRNA at much higher frequencies t han the other MAGE genes. MAGE-12 and MAGE-6 were expressed at the highest frequencies, relative to the other MAGE antigens, in early stage lesions. T he frequency of expression of all the MAGE genes was found to be higher in samples from metastatic deposits compared to those from locoregional diseas e. The cell lines all expressed the same or more MAGE antigens than the tum ours from which they were derived. In only one cell line was expression of a MAGE antigen lost. Certain recurring patterns of MAGE expression were obs erved in the tumour samples. MAGE-6 and/or -12 expression were detected in all of those 26 tumour samples that were positive for one or more of MAGE-1 , -2, -3 and -4. Twenty of these 26 samples expressed both antigens. These findings suggest that protocols targeting MAGE-12 and -6 would permit many more patients to be included into clinical cancer vaccination trials. (C) 2 000 Lippincott Williams & Wilkins.