Tumor cell–intrinsic EPHA2 suppresses antitumor immunity by regulating PTGS2 (COX-2)
Nune Markosyan, … , Ben Z. Stanger, Robert H. Vonderheide
Nune Markosyan, … , Ben Z. Stanger, Robert H. Vonderheide
Published June 4, 2019
Citation Information: J Clin Invest. 2019;129(9):3594-3609. https://doi.org/10.1172/JCI127755.
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Research Article Immunology Oncology

Tumor cell–intrinsic EPHA2 suppresses antitumor immunity by regulating PTGS2 (COX-2)

Abstract

Resistance to immunotherapy is one of the biggest problems of current oncotherapeutics. While T cell abundance is essential for tumor responsiveness to immunotherapy, factors that define the T cell–inflamed tumor microenvironment are not fully understood. We used an unbiased approach to identify tumor-intrinsic mechanisms shaping the immune tumor microenvironment (TME), focusing on pancreatic adenocarcinoma because it is refractory to immunotherapy and excludes T cells from the TME. From human tumors, we identified ephrin-A receptor 2 (EPHA2) as a candidate tumor-intrinsic driver of immunosuppression. Epha2 deletion reversed T cell exclusion and sensitized tumors to immunotherapy. We found that prostaglandin endoperoxide synthase 2 (PTGS2), the gene encoding cyclooxygenase-2, lies downstream of EPHA2 signaling through TGF-β and is associated with poor patient survival. Ptgs2 deletion reversed T cell exclusion and sensitized tumors to immunotherapy; pharmacological inhibition of PTGS2 was similarly effective. Thus, EPHA2/PTGS2 signaling in tumor cells regulates tumor immune phenotypes; blockade may represent a therapeutic avenue for immunotherapy-refractory cancers. Our findings warrant clinical trials testing the effectiveness of therapies combining EPHA2/TGF-β/PTGS2 pathway inhibitors with antitumor immunotherapy and may change the treatment of notoriously therapy-resistant pancreatic adenocarcinoma.

Authors

Nune Markosyan, Jinyang Li, Yu H. Sun, Lee P. Richman, Jeffrey H. Lin, Fangxue Yan, Liz Quinones, Yogev Sela, Taiji Yamazoe, Naomi Gordon, John W. Tobias, Katelyn T. Byrne, Andrew J. Rech, Garret A. FitzGerald, Ben Z. Stanger, Robert H. Vonderheide

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Figure 4

PTGS2 is a potential tumor cell–intrinsic regulator of TME.

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PTGS2 is a potential tumor cell–intrinsic regulator of TME. (A) Heatmap ...
(A) Heatmap of differentially expressed genes in Epha2-WT and Epha2-KO tumor cells from subcutaneously implanted tumors from indicated clones (n = 3–8/group). (B) Overlap of the genes enriched in Epha2-WT (vs. Epha2-KO) and T cell–low (vs. T cell–high) tumors. (C) Seventeen coenriched genes identified (B) in Epha2-WT and Epha2-KO tumor cells from subcutaneously implanted mouse tumors (clone 6694c2). (D) Boxplot of Ptgs2 gene expression (tpm) in mouse tumor cells of subcutaneously implanted T cell–low and T cell–high tumors (n = 8/group). (E) PTGS2 expression in human PDA samples in the upper and lower deciles of cytolytic index (n = 14/group). PDA samples retrieved from the TCGA data portal. (F) Survival of patients in the upper and lower deciles of PTGS2 expression (n = 17/group, TCGA PDA data set). (G) HOMER analysis of promoter regions of differentially expressed genes. Prediction of transcriptional regulators enriched in Epha2-WT and Epha2-KO tumor cells (n = 3–8/group). (H) TGF-β signaling GSEA in Epha2-WT versus Epha2-KO tumor cells (n = 3–8/group). (I) Relative expression of Ptgs2 mRNA in PDA tumor cell clones treated with either PBS or TGF-β for 72 hours. Data from n = 5 independent experiments. Color key represents the normalized Z score. (J) Relative expression of Ptgs2 mRNA in control (ctrl, empty vector transduced) and Smad3- and Smad4-KO 6419c5 PDA tumor cell lines. Data from n = 4 independent experiments. EV, empty vector. (K and L) Flow cytometric analysis of immune cell populations in control and Smad3-KO and Smad4-KO tumors (n = 8–10/group). (D, J–L) Data are presented as boxplots, with horizontal lines and error bars indicating mean and range, respectively. (E) Data are presented as mean with error bars indicating SEM. Statistical differences determined by Students’ t test (D and E) or 1-way ANOVA with Tukey’s HSD post test (J–L). The log-rank P value was calculated using GraphPad Prism (F). *P < 0.05; **P < 0.01; ***P < 0.001; ****P < 0.0001.