The Prediction, Identification And Cross-priming Evaluation Of HLA-A0201 Restricted CTL Epitopes Derived From SSX Gene Family

A vaccine based on antigen epitope has become a dominant strategy in the field of cancer research due to its relatively simple and stable moiety, easy preparation, and rarely potential contamination. This kind of antigen epitopes used currenently is mainly derived from cancer/testis antigen (CT antigen). SSX gene family, a 9-member family, is one of such CT antigens. Certain tumor cell type can express one or more but not all of SSX family member(s). Analyses of mRNA expression of 10 synovial sarcoma cell lines originated from six tissue types showed that 9, 5, 1, 6 and 5 of these cell lines expressed SSX-1, 2, 3, 4, and 5, respectively. The analyses also showed that each of these cell lines expressed at least one of SSX1-5 genes and 60% of these cell lines expressed two of the five genes simultaneously. Investigation of mRNA expression of 26 cases of primary hepatic carcinoma tissues demonstrated that 61.5%, 34.6% and 46.2% of these tissues expressed SSX1, SSX-2, and SSX-5 genes, respectively. It also indicated that 17 tissues (65.4%) could express at least one of these genes and two of three genes could be expressed simultaneously in 4 (15.4%) cancer tissues. There results suggest that epitope-based vaccine targeting only one of certain epitope derived from SSX family member protein would meet its limitaion for actual application. In contrast, epitope-based vaccines targeting epitope(s) shared between all SSX member proteins should be more promising in terms of practical application.In this study, cytotoxic T lymphocyte (CTL) epitopes of 9 members of SSX family were predicted with the super-motif combinding quantity-motif software exploited by Lin. The predicted epitopes were then analyzed further for their antigenicities with the known BIMAS software (http://www-bimas.cit.gov/molbio/hla_bind/) and SYFPEITHI software (http://www.syfpeithi.de/). These analyases showed that each SSX57-65 of the nine genes had high score for the epitope antigenicity, among all the predicted epitopes from the nine SSX...