Na17 And Mage Gene Expression In 20 Adult Sarcoma Tumors: Retrospective Analysis By Semi-Quantitative Rt-Pcr.

9053 Background: Expression of the MAGE-A family genes has been found in many types of tumors but not in normal adult tissues with the exception of testicular germ cells. A frequency of 20% MAGE mRNA positive sarcomas has been reported previously (Van den Eynde, Curr Opin Immunol 1997). NA17 is another tumor-associated antigen encoded by an intronal sequence from the N-acetylglucosaminyltransferase-V gene, which is significantly expressed in melanomas. Because NA17 and MAGE gene products are presented by HLA class I molecules and recognized by CD8+ cytolytic T lymphocytes in vivo, they have become promising target antigens for tumor vaccination in melanoma patients. Both are evaluated in ongoing melanoma vaccination trials at the Institut Curie. Methods: In 20 surgically resected bone and soft tissue sarcomas, expression of NA17 and Mage 1, 2, 3, 4, 6 and 10 was measured by semi-quantitative RT-PCR. After RNA extraction with CsCl gradient and reverse transcription, expression was quantified by PCR with comparison to dilutions of reference cell lines. All samples were histologically confirmed to contain tumoral tissue, corresponding to bone sarcomas in 8 and soft tissue sarcomas in 12 cases. Results: Analysis by the multimarker RT-PCR revealed an expression of at least one MAGE gene in 6 of 20 tumors, corresponding to a positivity rate of 30%. Among these 6 cases, MAGE 3 was expressed in 6, MAGE 6 in 4, MAGE 1 and MAGE 2 in 3, MAGE 4 and MAGE 10 in 2. For NA17, 5 of 20 samples exhibited positivity (25%). Overall, 8 of 20 tumors (40%) expressed at least one gene, and 4/20 (20%) expressed 3 or more genes simultaneously. Conclusions: This short series shows that NA17 and MAGE genes are expressed in 4/8 bone sarcomas and 4/12 soft tissue sarcomas. Sarcoma patients showing disease progression after conventional treatment might represent eligible candidates for HLA typing and future sarcoma vaccination trial combining NA17 and MAGE antigen immunization. No significant financial relationships to disclose.