Curability difference between autochthonous mouse tumors and their transplants in association with immune gene expression

Compared with transplanted tumors, autochthonous tumors are difficult to cure using experimental radiation therapy in mice. Here we analyzed differences in immune-related gene expression profiles between mouse fibrosarcomas subcutaneously induced by 3-methylcholanthrene (3MC) and their corresponding transplanted tumors. The immune genes examined were Pd1, Pdl1, Pdl2, Cd3d, Cd8a, Cd8b, Ifnγ, Itga2, Gzmb, and Foxp3. Among 12 tumors, one was non-transplantable and showed a benign phenotype with an abundance of DX5+ natural killer cells and CD8+ T cells together with increased IFNγ expression and mRNA levels of all immune genes except for Itga2. The other 11 transplantable tumors showed increased expression of Pd1, Pdl1, Pdl2, Cd3d, Cd8b, and Ifnγ following transplantation into syngeneic mice. These effects of transplantation highlight the relevance of immune gene expression status to the curability of tumors.