MAGE-1 and related MAGE gene expression may be associated with hepatocellular carcinoma

Purpose: The possibility of tumor rejection antigen, encoded by the MAGE-1 gene, being a target for immunotherapy in hepatocellular carcinoma (HCC) pa tients and the cloning of the full-length cDNA of this gene for subsequent studies were explored with the aim of discovering new immunotherapeutic str ategies for HCC. Methods: Expression of the MAGE-1 gene in HCC specimens an d HCC cell lines was examined by the reverse transcription/polymerase chain reaction (RT-PCR) with a pair of specific primers, which gave a 421-bp fra gment. Another pair of primers were then used to amplify the full-length MA GE-1 cDNA by the same method. The PCR products were then digested by restri ction endonucleases and inserted into the plasmid PUC19. After primary sele ction of the recombinants by endonuclease digestion, the sequences of the i nserted gene fragments were confirmed by DNA sequence analysis. Results: In 45 HCC patients, MAGE-1 mRNA was expressed in 27 tumor tissues (60%) and 5 paratumor tissues (11.1%). All the four HCC cell lines positively expresse d the MAGE-1 gene. Owing to the high homology of the MAGE gene family, we o btained three clones of different MAGE genes using the same pair of cloning primers. The three clones were confirmed to be a full-length MAGE-1 gene, a 750-bp fragment of the MAGE-3 gene and a fragment highly homologous to MA GE-6 and MAGE-12 but not identical to any known MAGE genes. Conclusion: The high expression frequency of MAGE-1 gene in HCC suggests the possibility o f using it as a target for immunotherapy in HCC patients. Some MAGE genes o ther than MAGE-1 may also be expressed in HCC together with an unknown MAGE gene that might introduce new targets for immune attacks. The three gene c lones obtained in this study can be used in further investigations and espe cially in the development of new liver cancer vaccines.