MUC1 glycoprotein is overexpressed on the surface of a variety of epithelial tumors and has been under investigation as a target for immunotherapy. A number of cytotoxic lymphocyte clones were generated in our laboratory from breast and pancreatic cancer patients that recognized MUC1 on the surface of tumor cells in a TCR-mediated MHC-unrestricted manner. The purpose of this study was to test the feasibility, efficacy and safety of using MHC-unrestricted MUC1-specific T cell receptor (TCR) gene transfer as a tool for cancer immunotherapy. The TCR £ and £] chains were cloned from one MHC-unrestricted MUC1-specific CTL clone (MA). Various configurations of chimeric TCRs were constructed and were expressed on the surface of a variety of cell lines in vitro. The TCR-deficient T cell line, Jurkat JRT3.5, transfected with the TCR £ and £] chains from MA CTL clone fluxed calcium in response to stimulation by a MUC1+ pancreatic human tumor, HPAF. BWZ murine thymoma cells transfected with a single-chain TCR (scTCR) consisting of the TCR extracellular domain and the CD3 ƒê signaling domain) were triggered to secrete IL-2 in response to stimulation with different MUC1+ tumor cells. The tumor recognition and rejection functions of this scTCR were tested in vivo when SCID mice were reconstituted with bone marrow (BM) cells transduced with scTCR-MFG retroviral supernatant and challenged with HPAF tumor cells. Tumor growth in mice reconstituted with scTCR-transduced BM cells was significantly slower (P<0.05) than that seen in the control group. Tumor sections from TCR-reconstituted mice were infiltrated by neutrophils and macrophages, and to lesser extent, by NK cells. FACS analyses showed that BM cells transduced with scTCR-MFG could differentiate in vivo into multiple immune lineages including T cells, B cells, granulocytes, monocytes and NK cells that express the scTCR. The scTCR was expressed on higher percentages of cells of the innate immune system when compared to T and B cells. Human MUC1 transgenic (Tg.) mice reconstituted with BM cells transduced with this MUC1-specific TCR did not show any signs of autoimmunity, abnormal cellular infiltration or destruction of MUC1-expressing tissues. Transduction of BM with tumor-specific TCR represents a potentially efficacious gene therapy/immunotherapy approach. MUC1-specific MHC-unrestricted TCR will make this treatment applicable to all cancer patients with MUC1+ tumors, regardless of their HLA type
