Cancer/testis (CT) antigens are a subgroup of tumor antigens with a restricted expression in normal testis and in different histological types of tumors. These antigens are considered promising candidates for cancer immunotherapy and the identification of new CT antigens is essential for the development of polyvalent cancer vaccines designed to overcome tumor heterogeneity and antigen loss. Immunological techniques such as T-lymphocyte epitope cloning and SEREX were initially used to identify new CT antigens. However, due to their restricted expression pattern, non-immunological techniques relying on differential mRNA expression have also been successfully used for the characterization of CT antigens. In the current study, we mined the Ludwig Transcriptome Database in order to identify in silico transcripts expressed exclusively in normal testis and/or tumors. After computational selection, the expression pattern of CT antigen candidates was validated by RT PCR using panels of cDNAs from 21 normal tissues and 17 tumor cell lines. A total of 1.255 candidates was identified and 93 of them were selected for experimental validation. Seven candidates showed to be expressed exclusively in testis among the 21 normal tissues analyzed and the expression of five of them was also detected in several tumor cell lines validating them as novel CT antigens. Furthermore, we were able to identify six novel candidates to cancer/testis/brain antigens (CTB). These antigens are expressed within normal tissues only in testis and brain and in different histological types of tumors. The expression of two of them was also detected in cell lines validating them as novel CTB antigens. Expression analysis in 160 samples derived from 9 different types of tumors is being carried out to confirm these results.
[Proc Amer Assoc Cancer Res, Volume 46, 2005]