Expression of MAGE-A3 and/or PRAME tumor antigens in South Korean gastric cancer patients

Abstract

MAGE-A3 (Melanoma AntiGen-A3) and PRAME (Preferentially expressed Antigen of MElanoma) are two tumor-associated antigens (TAAs) which have been extensively tested to develop antigen-specific cancer immunotherapy. This study aimed at determining the rate of expression of these TAAs in gastric cancer (GC), the association between clinico-pathological factors and TAA mRNA expression as well as investigating TAA expression as potential prognostic marker for patients' overall survival (OS). In addition, the association between the methylation status of the MAGE-A3 promoter region and its mRNA expression was examined. Archival formalin-fixed paraffin-embedded tissue specimens of resected tumors from 250 GC patients were investigated for TAA mRNA expression by quantitative reverse transcription polymerase chain reaction (qRT-PCR) and for protein expression of MAGE-A by immunohistochemistry. The methylation status of the MAGE-A3 promoter region was assessed by methylation-specific PCR. MAGE-A3 mRNA and protein expression was detected in 23.4% and 19.6% of the tumors, respectively, and 23.0% displayed an unmethylated MAGE-A3 promoter. The overall concordance between the three methods used to investigate expression of MAGE-A (3) was 75.0%. PRAME mRNA expression was found in 20.4% of the tumors, and 33.8% of them expressed at least one of the TAAs. Unlike the tumors in other organs, mRNA expression of either TAA was not associated with any of the clinic-pathological factors examined and neither did it show any potential as a prognostic biomarker for OS. No association was found between OS and the methylation status of the MAGE-A3 promoter region or with the tumor's protein expression of MAGE-A.