NF-κB regulates GDF-15 to suppress macrophage surveillance during early tumor development
Nivedita M. Ratnam, Jennifer M. Peterson, Erin E. Talbert, Katherine J. Ladner, Priyani V. Rajasekera, Carl R. Schmidt, Mary E. Dillhoff, Benjamin J. Swanson, Ericka Haverick, Raleigh D. Kladney, Terence M. Williams, Gustavo W. Leone, David J. Wang, Denis C. Guttridge
Nivedita M. Ratnam, Jennifer M. Peterson, Erin E. Talbert, Katherine J. Ladner, Priyani V. Rajasekera, Carl R. Schmidt, Mary E. Dillhoff, Benjamin J. Swanson, Ericka Haverick, Raleigh D. Kladney, Terence M. Williams, Gustavo W. Leone, David J. Wang, Denis C. Guttridge
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Research Article Cell biology Immunology

NF-κB regulates GDF-15 to suppress macrophage surveillance during early tumor development

Abstract

Macrophages are attracted to developing tumors and can participate in immune surveillance to eliminate neoplastic cells. In response, neoplastic cells utilize NF-κB to suppress this killing activity, but the mechanisms underlying their self-protection remain unclear. Here, we report that this dynamic interaction between tumor cells and macrophages is integrally linked by a soluble factor identified as growth and differentiation factor 15 (GDF-15). In vitro, tumor-derived GDF-15 signals in macrophages to suppress their proapoptotic activity by inhibiting TNF and nitric oxide (NO) production. In vivo, depletion of GDF-15 in Ras-driven tumor xenografts and in an orthotopic model of pancreatic cancer delayed tumor development. This delay correlated with increased infiltrating antitumor macrophages. Further, production of GDF-15 is directly regulated by NF-κB, and the colocalization of activated NF-κB and GDF-15 in epithelial ducts of human pancreatic adenocarcinoma supports the importance of this observation. Mechanistically, we found that GDF-15 suppresses macrophage activity by inhibiting TGF-β–activated kinase (TAK1) signaling to NF-κB, thereby blocking synthesis of TNF and NO. Based on these results, we propose that the NF-κB/GDF-15 regulatory axis is important for tumor cells in evading macrophage immune surveillance during the early stages of tumorigenesis.

Authors

Nivedita M. Ratnam, Jennifer M. Peterson, Erin E. Talbert, Katherine J. Ladner, Priyani V. Rajasekera, Carl R. Schmidt, Mary E. Dillhoff, Benjamin J. Swanson, Ericka Haverick, Raleigh D. Kladney, Terence M. Williams, Gustavo W. Leone, David J. Wang, Denis C. Guttridge

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Figure 2

GDF-15 is required for early development of Panc02 tumors.

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GDF-15 is required for early development of Panc02 tumors. (A) Kaplan-Me...
(A) Kaplan-Meier curve assessing the effects of GDF-15 expression on patient survival obtained from 165 patients in TCGA and 108 patients from a published study on the GEO database (ref. 13). Blue line represents PDAC patients with low GDF-15 expression, white line represents patients with medium GDF-15, and red line indicates patients with high GDF-15. Asterisks compare GDF-15 high and low groups. (B) Panc02 cells expressing an shRNA against Gdf-15 (2 clones, numbers 12 and 15) were cocultured with peritoneal macrophages for 48 hours. The cells were then stained for annexin V, 7-AAD, and CD11b and analyzed by flow cytometry. CD11b– cells positive for annexin V, 7-AAD, or both were graphed as percentage of cell death. Data represent mean ± SEM from 2 individual experiments, performed in triplicate. *P ≤ 0.05, 1-way ANOVA. (C) Panc02 control and Panc02 Gdf-15–knockdown cells (described above as clone 12) were injected orthotopically into the tail of the pancreas in C57BL/6 mice. Tumor weight was measured as weight of pancreas with tumor minus average weight of Matrigel-injected pancreas. Data represent the average tumor weight from cohorts of 5 to 7 mice per group per time point ± SEM. *P ≤ 0.05, SPSS repeated measures, general linear model. (D) Control and Gdf-15–knockdown orthotopic tumors described in C were sectioned and analyzed for H&E, Ki67, and CC3. Original magnification, ×20. Scale bars: 15 μm. (E) Ki67 and CC3 staining was quantitated and graphed from 5 mice per condition at each time point, from 5 random fields of view of the tumor area per mouse. Mean ± SEM. *P ≤ 0.05, Student’s t test.