Dormant tumors circumvent tumor-specific adaptive immunity by establishing a Treg-dominated niche via DKK3
Timothy N. Trotter, Carina E. Dagotto, Delila Serra, Tao Wang, Xiao Yang, Chaitanya R. Acharya, Junping Wei, Gangjun Lei, H. Kim Lyerly, Zachary C. Hartman
Timothy N. Trotter, Carina E. Dagotto, Delila Serra, Tao Wang, Xiao Yang, Chaitanya R. Acharya, Junping Wei, Gangjun Lei, H. Kim Lyerly, Zachary C. Hartman
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Research Article Immunology Oncology

Dormant tumors circumvent tumor-specific adaptive immunity by establishing a Treg-dominated niche via DKK3

Abstract

Approximately 30% of breast cancer survivors deemed free of disease will experience locoregional or metastatic recurrence even up to 30 years after initial diagnosis, yet how residual/dormant tumor cells escape immunity elicited by the primary tumor remains unclear. We demonstrate that intrinsically dormant tumor cells are indeed recognized and lysed by antigen-specific T cells in vitro and elicit robust immune responses in vivo. However, despite close proximity to CD8+ killer T cells, dormant tumor cells themselves support early accumulation of protective FoxP3+ T regulatory cells (Tregs), which can be targeted to reduce tumor burden. These intrinsically dormant tumor cells maintain a hybrid epithelial/mesenchymal state that is associated with immune dysfunction, and we find that the tumor-derived, stem cell/basal cell protein Dickkopf WNT signaling pathway inhibitor 3 (DKK3) is critical for Treg inhibition of CD8+ T cells. We also demonstrate that DKK3 promotes immune-mediated progression of proliferative tumors and is significantly associated with poor survival and immunosuppression in human breast cancers. Together, these findings reveal that latent tumors can use fundamental mechanisms of tolerance to alter the T cell microenvironment and subvert immune detection. Thus, targeting these pathways, such as DKK3, may help render dormant tumors susceptible to immunotherapies.

Authors

Timothy N. Trotter, Carina E. Dagotto, Delila Serra, Tao Wang, Xiao Yang, Chaitanya R. Acharya, Junping Wei, Gangjun Lei, H. Kim Lyerly, Zachary C. Hartman

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Figure 5

D2.1 cells directly induce CD4+ Tregs that can target in vivo.

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D2.1 cells directly induce CD4+ Tregs that can target in vivo. (A) Whole...
(A) Whole Jedi splenocytes were stained with CellTrace and stimulated with anti-CD28 antibodies and GFP200–208 peptides in conditioned medium (CM) from D2A1 cells or D2.1 cells for 3 days followed by flow cytometric analysis. (B) Total T cells (CD45+CD11b–CD4+ or CD45+CD11b–CD8β+) among immune cells (CD45+) at the end of culture. (C) Representative flow plots of CD4+ and CD8+ T cells among CD45+ cells and proportion of total CD4+ and CD8+ cells among CD45+ cells. (D and E) Representative flow plots (left) and quantification of divisions (right) of CellTrace-stained CD8+ cells (D) or CD4+ cells (E) in D2A1 or D2.1 CM. (F) Representative plots (left) and quantification (right) of FoxP3+ Tregs in D2A1 and D2.1 CM after 3 days in culture. (G) CD8+/Treg ratio in T cells in D2A1 or D2.1 CM. All conditions were performed in triplicate. Statistical comparisons were performed by 2-tailed t test (B, C, F, and G) or Šídák’s 2-way ANOVA (D and E). (H) Growth of D2.1 tumors (1 × 106 cells/mammary fat pad) treated with anti-CTLA4 antibodies (n = 10) or isotype control (n = 9) upon reaching 150 mm3. (I) D2.1 (1 × 106 cells/mammary fat pad) were implanted into female FoxP3-DTR mice and received 0 ng/g DT (Untreated) or 5 doses of 25 ng/g every 4 days (arrows) beginning on day 35 (DT Early) or day 70 (DT late). (J) D2.1 tumor volume comparing all Untreated (n = 14) mice to DT Early (n = 9) at time of DT Early euthanasia (left) or comparing remaining Untreated mice to DT Late (n = 8 each) at end of experiment (right). Statistical comparisons for H and J were performed by Šidák’s 2-way ANOVA and P values shown are at the final time point. Data are presented as mean ± SEM.