Human NY-ESO-1 gene encodes for an antigen belonging to cancer/testis (CT) protein. NY-ESO-1 gene is expressed in many human cancers with various histological types, but not in normal tissues except testis. The NY-ESO-1 antigen is a potential target for cancer immunotherapy. We investigated the expression of gene NY-ESO-1 in the samples of hepatocellular carcinoma (HCC) tissues and adjacent liver tissues by RT-PCR. 56 of 124 tumor tissues from HCC patients were NY-ESO-1 positive (45.2%). In contrast, NY-ESO-1 mRNA was not detected in any of the adjacent tissues. A cDNA fragment of 329bp was amplified by RT-PCR from each of the 56 positive samples and sequenced. Four samples were found to have point mutations at 2 sites resulting in a substitution of one amino acid residue. Such substitution is predicted to have a profound effect on the protein structure and hence on the functional motif in the protein. To distinguish whether the substitution is a point mutation or a polymorphism present in normal population, the genomic DNA fragment has been amplified from 10 samples of the peripheral blood mononuclear cells (PBMCs) of healthy donors and sequenced. All the tested samples displayed the same sequence as that had been reported. Thus, the base pair change occurred in HCCs is maybe a point mutation. In HCCs, the expression of NY-ESO-1 has no correlation with other parameters tested, such as tumor markers (aFP, AFU), metastasis, recurrence, and tumor diameter (P<0.05). The relatively high rate of NY-ESO-1 gene expression in HCCs indicates that NY-ESO-1 protein may be a vaccine candidate to be developed as immunotherapy for HCC patients.
