This project considers the involvement of induced immunogenicity in the cure and prevention of rat glioblastoma in the brain as well as the cure and prevention of hepatocarcinoma. We plan to inject parental glioma C6 cells into rat brain. After the tumor is established, transfected cells expressing insulin-like growth factor-I (IGF-I) antisense RNA will be injected either directly into the brain tumor or subcutaneously at a distal site. Such treatment cures experimentally established subcutaneous and brain glioblastoma tumors via an immune response. Therefore, brain tumors will be analyzed by immunocytochemistry for the identification of the immune system cell types participating in the cure in three additional rodent glioblastoma cell lines with an established tumors in the syngeneic animal in order to determine the generality of the phenomenon. The possibility that irradiated cells (incapable of division) can activate the immune system in other cell lines as they do with C6 cells will be studied with all additional cell lines. Glioma cells transfected with antisense vector blocking the expression of IGF type-I receptor will be generated and injected to test whether the receptor participates in an intracrine mechanism(s) underlying tumorigenicity and immunogenicity. The interrelationships between the expression of IGF-I and the major histocompatibility complex-I (MHC-I) will be followed. Other participants in immune recognition, such as cell surface and soluble co-stimulatory molecules, will be assessed. Severe Combined Immune Deficiency (SCID) mice will be implanted with patients lymphocytes in mice carrying glioblastoma tumor of the same donor. This system will he used to study immunogenicity of transfected tumor cells expressing antisense IGF-I cDNA. The second model system, hepatocell carcinoma (generated by the BRL-3A cell line) will also be studied. These cells express IGF-II as does fetal liver. They will be transfected with antisense episome-based IGF-II plasmid and the tumorigenicity and ability to involve the immune response in vivo will be studied. The potential role of IGF receptors in altered tumor cell immunogenicity will be evaluated through antisense gene transfer by a double transfection with IGF type-I and type-II receptors.
