Expression of MAGE-1 and-3 genes and gene products in human hepatocellularcarcinoma

MAGE gene family encodes peptides recognized by autologous cytotoxic T lymp hocytes in a major histocompatibility complex (MHC) class-I restricted fash ion. In the present study, we have performed reverse-transcription polymera se chain reaction (RT-PCR) for the genes, as well as immunohistochemical an alysis and Western blotting of MAGE-1 and -3 proteins in 33 surgically rese cted hepatocellular carcinomas (HCCs). MAGE-1 and -3 mRNAs were constitutiv ely expressed exclusively in 78 and 42% of HCCs respectively. On immunohist ochemistry with monoclonal antibodies, 77B for MAGE-1 and 57B for MAGE-3, M AGE-1 and -3 proteins were recognized in cytoplasm of only six among 33 (18 %) and two of 29 HCCs (7%) respectively. The distribution pattern was mostl y focal in HCC nodules. By contrast, the Western blot analysis revealed tha t the MAGE-1 (46 kDa) and -3 proteins (48 kDa) were expressed in 80 and 60% of 15 HCCs examined respectively. The proteins of MAGE-1 and -3 were also expressed exclusively in HCCs regardless of the histological grading and cl inical staging. Our results indicate that the detection of the genes by RT- PCR or the proteins by Western blotting is useful for differentiating early HCCs from noncancerous lesions. and that the peptides derived from MAGE-1 and -3 proteins might be suitable targets for immunotherapy of human HCC. ( C) 1999 Cancer Research Campaign.