NF-κB regulates GDF-15 to suppress macrophage surveillance during early tumor development
Nivedita M. Ratnam ... David J. Wang, Denis C. Guttridge
Nivedita M. Ratnam ... David J. Wang, Denis C. Guttridge
Published September 11, 2017
Citation Information: J Clin Invest. 2017. doi:10.1172/JCI91561.
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Categories: 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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GDF-15 protects transformed cells against macrophages and promotes tumor...

Figure 1

GDF-15 protects transformed cells against macrophages and promotes tumor development in vivo.

(A) p65–/–Ras MEFs were cocultured with peritoneal macrophages (MΦ) with normal or conditioned media from p65+/+Ras MEFs. Graph represents cell survival scored by trypan blue exclusion, normalized to untreated p65–/–Ras MEFs. n = 6. Data are shown as mean ± SEM. *P ≤ 0.05, 1-way ANOVA. (B) Gdf-15 analyzed by qRT-PCR in Ras MEFs normalized to Gapdh ± SEM. *P ≤ 0.05, Student’s t test. n = 3. (C) GDF-15 ELISA from Ras MEF–conditioned media. n = 3. Data are shown as mean ± SEM. *P ≤ 0.05, Student’s t test. (D) Ras MEFs were cocultured with macrophages and GDF-15–neutralizing antibody (GDF-15 Ab) at concentrations of 0, 25, 625, and 2,500 ng/ml. Graph represents cell survival similar to that shown in A. Data are shown as mean ± SEM from 2 independent experiments, each performed in triplicate. *P ≤ 0.05, 1-way ANOVA. (E) p65–/–Ras MEFs were cocultured with macrophages and recombinant GDF-15 (rGDF-15) at concentrations of 0, 5, and 10 ng/ml. Graph represents cell survival similar to that shown in A. Data represent mean ± SEM derived from 2 independent experiments, each performed in triplicate. *P ≤ 0.05, 1-way ANOVA. (F) p65+/+Ras MEFs (1 × 106) were injected subcutaneously into SCID mice. Cohorts of mice (n = 5) were intravenously injected with GDF-15 antibody (20 μg/mouse) or IgG control (20 μg/mouse) and tumor sizes measured. Arrowheads indicate time points for injections. Data are shown as mean ± SEM. *P ≤ 0.05, SPSS repeated measures, general linear model. (G) Single clones from Ras MEFs expressing Gdf-15 shRNA or scrambled control (sh control) were subcutaneously injected into SCID mice and tumor sizes measured. Data represent mean tumor diameter from 2 single clones (Scr-1 and Scr-2 for scrambled controls and C2 and D2 for Gdf-15–knockdown) injected into 5 mice each. Data are shown as mean ± SEM. *P ≤ 0.05, SPSS repeated measures, general linear model.