A new strategy for the diagnosis of MAGE-expressing cancers

Abstract

The expression of melanoma antigen gene (MAGE), coding for tumor antigens recognized by cytotoxic T cell, is highly specific to cancer cells, but their use in the detection of a few cancer cells by reverse transcription-polymerase chain reaction (RT-PCR) has been limited by the low frequency of expression of individual MAGE genes. In order to increase MAGE detection rate in RT-PCR assay, here, we designed multiple MAGEs recognizing primers (MMRPs) that can bind to the sequences of cDNA of MAGE-1, -2, -3, -4a, -4b, -5a, -5b and-6 (MAGE 1–6) together. The nested RT-PCR assay using MMRPs, MAGE 1–6 assay, detected MAGE messages of 1 to 5 SNU484 cells in a background of 107 SNU638 cells. MAGE detection rate of MAGE 1–6 assay in cancers was higher than that of nested RT-PCR that detects single MAGE gene expression. The expressions of MAGE genes was detected by MAGE 1–6 assay in 70.4% (19/27) of head and neck cancer tissues, 91.7% (11/12) of breast cancer tissues, 75% (9/12) of lung cancer tissues. However, they were not detected in 18 benign lesions and 20 normal head and neck tissues and 30 blood samples from healthy donor. In conclusions, MAGE 1–6 assay can detect any cancer cells that express at least one of eight MAGE subtype genes, and this method may be very useful for the diagnosis of MAGE-expressing cancers.