Evaluation of SEREX defined antigens by mRNA expression analysis in breast cancer tissues of Egyptian patients

The identification of human cancer antigens has opened new approaches to the development of cancer vaccines. Characterization of the defined antigens including mRNA expression analysis, protein analysis, antibody response and epitope identification are important to assess the value of those antigens.The aim of the present work is to identify tumor specific or tumor associated antigens by serological analysis of recombinant cDNA expression library (SEREX). Different cancer cell lines and normal testis were used as a source of cDNA library in this study including lung cancer, renal cancer, colon cancer and ovarian cancer in addition to a testicular library. For immunoscreening, autologous as well as allogeneic sera were obtained. By autologous immunoscreening, we previously reported the SEREX analysis of the lung adenocarcinoma cell line OU-LU-6 including the identification of the cancer/testis antigen XAGE-1b. We also reported the SEREX analysis of the lung adenocarcinoma cell lines OU-LU-17 and OU-LU-11. This work focused on the defined SEREX genes by autologous and allogeneic immunoscreening of the renal cancer cell line RC-1. The total number of defined clones was 51 representing 39 different genes named OYREN-1 through OY-REN-39. The vast majority of clones identified by SEREX are ubiquitously expressed genes. In the renal cancer cell line RC-1, OY-REN-1, 3, 18, 29 and 31 genes were the most frequently isolated (3 of 51), subsequently, OY-REN-2 and 30 were the second most frequent isolated genes, each was represented by 2 of 51 clones. All other genes were represented by a single clone. Within the isolated genes, protein kinase c, Iota (PKCI) which clones had a deletion compared to sequences in the database which might give the chance to identify a new isoform. mRNA expression analysis of PKCI in normal as well as breast cancer tissues showed no cancer specific characteristics compared to the cancer/testis antigen XAGE-1b and c variants. Very interestingly, XAGE-1b antigen showed a significantly high frequency of expression in breast cancer tissues (5/10) taken from Egyptian patients. Using the SEREX defined antigens for mRNA expression in breast cancer tissues may aid the development of diagnostic and immunotherapeutic agents for patients with breast cancer in Egypt.