Wei, Wei‐Zen

Abstract Earlier, we demonstrated the essential role of Kruppel-like transcription factor, TIEG1, in TGF-β–induced regulatory T cell (Treg) development. In this article, we demonstrate that IL-6, which promotes Th17 development, abrogated TIEG1 nuclear translocation and inhibited TGF-β–induced Treg development. Tyrosine kinase Tyk2-mediated phosphorylation of TIEG1 at Tyr179 promoted noncanonical K-27–linked polyubiquitination, which inhibited TIEG1 nuclear translocation. To test the role of TIEG1-regulated Treg/Th17 development in antitumor immunity, we analyzed TRAMP-C2 tumor growth in TIEG1−/− mice. The defective Treg development and elevated Th17 response resulted in enhanced immune reactivity in the tumor and inhibition of TRAMP-C2 tumor growth in TIEG1−/− mice. Thus, our results uncovered a novel regulatory mechanism that modulates Tregs and may regulate tumor progression.

Abstract Immune reactivity to self-antigens in both cancer and autoimmune diseases can be enhanced by systemic immune modulation, posing a challenge in cancer immunotherapy. To distinguish the genetic and immune regulation of tumor immunity versus autoimmunity, immune responses to human ErbB-2 (Her-2) and mouse thyroglobulin (mTg) were tested in transgenic mice expressing Her-2 that is overexpressed in several cancers, and HLA-DRB1*0301 (DR3) that is associated with susceptibility to several human autoimmune diseases, as well as experimental autoimmune thyroiditis (EAT). To induce Her-2 response, mice were electrovaccinated with pE2TM and pGM-CSF encoding the extracellular and transmembrane domains of Her-2 and the murine granulocyte macrophage colony-stimulating factor, respectively. To induce EAT, mice received mTg i.v. with or without lipopolysaccharide. Depletion of regulatory T cells (Treg) with anti-CD25 monoclonal antibody enhanced immune reactivity to Her-2 as well as mTg, showing control of both Her-2 and mTg responses by Treg. When immunized with, Her-2xDR3 and B6xDR3 mice expressing H2bxDR3 haplotype developed more profound mTg response and thyroid pathology than Her-2 or B6 mice that expressed the EAT-resistant H2b haplotype. In Her-2xDR3 mice, the response to mTg was further amplified when mice were also immunized with pE2TM and pGM-CSF. On the contrary, Her-2 reactivity was comparable whether mice expressed DR3 or not. Therefore, induction of Her-2 immunity was independent of DR3 but development of EAT was dictated by this allele, whereas Tregs control the responses to both self-antigens. These results warrant close monitoring of autoimmunity during cancer immunotherapy, particularly in patients with susceptible MHC class II alleles. [Cancer Res 2007;67(14):7020–7]