New Strategy for the Identification of Squamous Carcinoma Antigens that Induce Therapeutic Immune Responses in Tumor-Bearing Mice
Session type: Poster / e-Poster / Silent Theatre session
Title: New Strategy for the Identification of Tumor-associated Antigens that Induce Therapeutic Immune Responses in Tumor-bearing Mice
Edward P. Cohen, Professor, emeritus University of Illinois College of Medicine
Here is describe a unique strategy designed to identify dominant tumor antigens associated with lung cancer cells In a squamous carcinoma mouse model of non-small cell lung cancer, the antigen-discovery strategy is based on the finding that genes encoding Dominant Tumor-associated Antigens (TAA) are expressed in a highly immunogenic form by a nonmalignant, allogeneic fibroblast cell line transfected with a cDNA expression library from lung cancer cells. A unique strategy was developed that resulted in the identification of Cyp2e1, a derivative of cytochrome p450, as an immune dominant tumor antigen in murine squamous carcinoma cells and growth factor receptor bound protein 10 (GRB10) as an immune dominant tumor antigen in murine breast cancer cells.
Aliquots of the suspension of transfected cells were divided into 10-15 small pools (initial inoculums 10E3, Small starting inoculums increase the likelihood that some pools will contain greater numbers of cells that express cancer antigens than others) and then dividing the transfected cell-populations from each pool into two portions. One portion was maintained frozen/viable for later recovery. The remaining portion was co incubated with (mitomycin C-treated) squamous carcinoma cells. (ELISPOT interferon gamma-release and 51-Cr release cytotoxicity) were used to identify pools that stimulated immunity to the squamous carcinoma cells to the greatest and to the least extent. Cells from these pools were reestablished in culture, the cell-numbers were expanded and subdivided for additional rounds of immune selection. Cyp2e1, a derivative to cytochrome p40 was identified as a dominant tumor antigen. A vaccine was prepared by transfer of an expression vector specifying the candidate gene into an allogeneic cell line followed by immunization of mice with squamous cell cancer.