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MPGES-1-derived PGE2 suppresses CD80 expression on tumor-associated phagocytes to inhibit anti-tumor immune responses in breast cancer.

Olesch C, Sha W, Angioni C, Sha LK, Açaf E, Patrignani P, Jakobsson PJ, Radeke HH, Grösch S, Geisslinger G, von Knethen A, Weigert A, Brüne B - Oncotarget (2015)

Bottom Line: Pharmacological mPGES-1 inhibition increased CD80 expression, whereas addition of PGE2, a prostaglandin E2 receptor 2 (EP2) agonist, or activation of signaling downstream of EP2 reduced CD80 expression.Genetic ablation of mPGES-1 resulted in markedly reduced tumor growth in PyMT mice.In conclusion, mPGES-1 inhibition elevates CD80 expression by tumor-associated phagocytes to restrict tumor growth.

View Article: PubMed Central - PubMed

Affiliation: Institute of Biochemistry I, Faculty of Medicine, Goethe-University Frankfurt, Frankfurt, Germany.

ABSTRACT
Prostaglandin E2 (PGE2) favors multiple aspects of tumor development and immune evasion. Therefore, microsomal prostaglandin E synthase (mPGES-1/-2), is a potential target for cancer therapy. We explored whether inhibiting mPGES-1 in human and mouse models of breast cancer affects tumor-associated immunity. A new model of breast tumor spheroid killing by human PBMCs was developed. In this model, tumor killing required CD80 expression by tumor-associated phagocytes to trigger cytotoxic T cell activation. Pharmacological mPGES-1 inhibition increased CD80 expression, whereas addition of PGE2, a prostaglandin E2 receptor 2 (EP2) agonist, or activation of signaling downstream of EP2 reduced CD80 expression. Genetic ablation of mPGES-1 resulted in markedly reduced tumor growth in PyMT mice. Macrophages of mPGES-1(-/-) PyMT mice indeed expressed elevated levels of CD80 compared to their wildtype counterparts. CD80 expression in tumor-spheroid infiltrating mPGES-1(-/-) macrophages translated into antigen-specific cytotoxic T cell activation. In conclusion, mPGES-1 inhibition elevates CD80 expression by tumor-associated phagocytes to restrict tumor growth. We propose that mPGES-1 inhibition in combination with immune cell activation might be part of a therapeutic strategy to overcome the immunosuppressive tumor microenvironment.

No MeSH data available.


Related in: MedlinePlus

MPGES-1-deficiency promotes CTL activation by tumor-associated macrophages(A-E) Bone marrow monocytes of WT or mPGES-1−/− mice were pre-stimulated with LPS/IFN-γ for 30 min and cocultured with E0771 tumor spheroids for 24 h. Afterwards, OVA SIINFEKL peptide was added for 1 h followed by addition of spleen-derived OT-I CTLs for another 4 days. Afterwards cocultures were analyzed by flow cytometry. (A) CD80 and (B) CD86 expression of CD11b+ F4/80+ monocyte-derived macrophages (BMDM) is displayed. Data are means ± SEM of four independent experiments. (C) A representative histogram and (D) a quantification of proliferating OT-I T cells is displayed. (E) The relative amount of GrBhi CTLs is shown. Data are means ± SEM of four independent experiments using cells of 4 WT and 4 mPGES-1−/− mice. (F,G) Pre-activated spleen-derived CTLs of WT or mPGES-1−/− mice were cocultured with E0771 tumor spheroids for 3 days. (F) The relative amount of proliferating T cells and (G) the relative amount of GrBhi CTLs is shown. Data are means ± SEM of four independent experiments using cells of 4 WT and 4 mPGES-1−/− mice. p-values were calculated using student's t-test. Asterisks indicate significant differences between experimental groups (*, p ≤ .05).
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Figure 7: MPGES-1-deficiency promotes CTL activation by tumor-associated macrophages(A-E) Bone marrow monocytes of WT or mPGES-1−/− mice were pre-stimulated with LPS/IFN-γ for 30 min and cocultured with E0771 tumor spheroids for 24 h. Afterwards, OVA SIINFEKL peptide was added for 1 h followed by addition of spleen-derived OT-I CTLs for another 4 days. Afterwards cocultures were analyzed by flow cytometry. (A) CD80 and (B) CD86 expression of CD11b+ F4/80+ monocyte-derived macrophages (BMDM) is displayed. Data are means ± SEM of four independent experiments. (C) A representative histogram and (D) a quantification of proliferating OT-I T cells is displayed. (E) The relative amount of GrBhi CTLs is shown. Data are means ± SEM of four independent experiments using cells of 4 WT and 4 mPGES-1−/− mice. (F,G) Pre-activated spleen-derived CTLs of WT or mPGES-1−/− mice were cocultured with E0771 tumor spheroids for 3 days. (F) The relative amount of proliferating T cells and (G) the relative amount of GrBhi CTLs is shown. Data are means ± SEM of four independent experiments using cells of 4 WT and 4 mPGES-1−/− mice. p-values were calculated using student's t-test. Asterisks indicate significant differences between experimental groups (*, p ≤ .05).

Mentions: Following the hypothesis that a reduced occurrence of mPGES-1−/− PyMT tumors was due to enhanced immune control, we wondered if elevated CD80 expression in mPGES-1−/− murine macrophages translates into CTL activation. First, we asked whether enhanced CD80 was observed in mPGES-1−/− BMDM stimulated with LPS/IFN-γ compared to WT macrophages. Interestingly, mPGES-1−/− BMDM, which barely produced PGE2, did not show alterations in CD80 or CD86 induction compared to WT BMDM after stimulation with LPS/IFN-γ (Figure S3C,D). Thus, not only an activating stimulus per se, but also the tumor milieu might be necessary to reveal immune modulating effects of PGE2. These selective immune modulating effects of PGE2 might be most apparent in a set-up that comprises both inflammatory (LPS/IFN-γ) as well as anti-inflammatory (breast tumor microenvironment) components. To test this hypothesis we generated tumor spheroids of E0771 murine mammary carcinoma cells. These spheroids were incubated with LPS/IFN-γ-stimulated WT or mPGES-1−/− bone marrow monocytes for 24 h, followed by addition of OVA SIINFEKL as a model antigen and spleen-derived OT-I CTLs for another 4 days. These T cells specifically recognize the OVA SIINFEKL peptide, resulting in a model of antigen-specific CTL activation in the tumor microenvironment. In this setting, mPGES-1−/− monocyte-derived tumor spheroid-infiltrating macrophages indeed expressed higher CD80, but not CD86, levels compared to wildtype macrophages (Figure 7A,B). These data corroborated our findings in the PyMT model. Spheroid-infiltrating OT-I cells displayed higher rates of proliferation (Figure 7C,D) and GrB expression (Figure 7E) when spheroids contained mPGES-1−/− monocyte-derived macrophages compared to WT macrophages. These data support the notion that reduced tumor growth in mPGES-1−/− PyMT mice was due to enhanced immune control. Importantly, infiltration of pre-activated WT or mPGES-1−/− spleen CTLs did not affect T cell proliferation or GrB expression (Figure 7F,G). These novel data demonstrate that mPGES-1-deficiency does not affect basic CTL function. Thus, a direct impact of mPGES-1-deficiency on CTL function in PyMT tumors was unlikely contributing to the phenotype of mPGES-1−/− PyMT mice. We conclude that mPGES-1−/− TAMs support CTL activation. This might be an important mechanism in restricting tumor occurrence in mPGES-1−/− PyMT mice.


MPGES-1-derived PGE2 suppresses CD80 expression on tumor-associated phagocytes to inhibit anti-tumor immune responses in breast cancer.

Olesch C, Sha W, Angioni C, Sha LK, Açaf E, Patrignani P, Jakobsson PJ, Radeke HH, Grösch S, Geisslinger G, von Knethen A, Weigert A, Brüne B - Oncotarget (2015)

MPGES-1-deficiency promotes CTL activation by tumor-associated macrophages(A-E) Bone marrow monocytes of WT or mPGES-1−/− mice were pre-stimulated with LPS/IFN-γ for 30 min and cocultured with E0771 tumor spheroids for 24 h. Afterwards, OVA SIINFEKL peptide was added for 1 h followed by addition of spleen-derived OT-I CTLs for another 4 days. Afterwards cocultures were analyzed by flow cytometry. (A) CD80 and (B) CD86 expression of CD11b+ F4/80+ monocyte-derived macrophages (BMDM) is displayed. Data are means ± SEM of four independent experiments. (C) A representative histogram and (D) a quantification of proliferating OT-I T cells is displayed. (E) The relative amount of GrBhi CTLs is shown. Data are means ± SEM of four independent experiments using cells of 4 WT and 4 mPGES-1−/− mice. (F,G) Pre-activated spleen-derived CTLs of WT or mPGES-1−/− mice were cocultured with E0771 tumor spheroids for 3 days. (F) The relative amount of proliferating T cells and (G) the relative amount of GrBhi CTLs is shown. Data are means ± SEM of four independent experiments using cells of 4 WT and 4 mPGES-1−/− mice. p-values were calculated using student's t-test. Asterisks indicate significant differences between experimental groups (*, p ≤ .05).
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Figure 7: MPGES-1-deficiency promotes CTL activation by tumor-associated macrophages(A-E) Bone marrow monocytes of WT or mPGES-1−/− mice were pre-stimulated with LPS/IFN-γ for 30 min and cocultured with E0771 tumor spheroids for 24 h. Afterwards, OVA SIINFEKL peptide was added for 1 h followed by addition of spleen-derived OT-I CTLs for another 4 days. Afterwards cocultures were analyzed by flow cytometry. (A) CD80 and (B) CD86 expression of CD11b+ F4/80+ monocyte-derived macrophages (BMDM) is displayed. Data are means ± SEM of four independent experiments. (C) A representative histogram and (D) a quantification of proliferating OT-I T cells is displayed. (E) The relative amount of GrBhi CTLs is shown. Data are means ± SEM of four independent experiments using cells of 4 WT and 4 mPGES-1−/− mice. (F,G) Pre-activated spleen-derived CTLs of WT or mPGES-1−/− mice were cocultured with E0771 tumor spheroids for 3 days. (F) The relative amount of proliferating T cells and (G) the relative amount of GrBhi CTLs is shown. Data are means ± SEM of four independent experiments using cells of 4 WT and 4 mPGES-1−/− mice. p-values were calculated using student's t-test. Asterisks indicate significant differences between experimental groups (*, p ≤ .05).
Mentions: Following the hypothesis that a reduced occurrence of mPGES-1−/− PyMT tumors was due to enhanced immune control, we wondered if elevated CD80 expression in mPGES-1−/− murine macrophages translates into CTL activation. First, we asked whether enhanced CD80 was observed in mPGES-1−/− BMDM stimulated with LPS/IFN-γ compared to WT macrophages. Interestingly, mPGES-1−/− BMDM, which barely produced PGE2, did not show alterations in CD80 or CD86 induction compared to WT BMDM after stimulation with LPS/IFN-γ (Figure S3C,D). Thus, not only an activating stimulus per se, but also the tumor milieu might be necessary to reveal immune modulating effects of PGE2. These selective immune modulating effects of PGE2 might be most apparent in a set-up that comprises both inflammatory (LPS/IFN-γ) as well as anti-inflammatory (breast tumor microenvironment) components. To test this hypothesis we generated tumor spheroids of E0771 murine mammary carcinoma cells. These spheroids were incubated with LPS/IFN-γ-stimulated WT or mPGES-1−/− bone marrow monocytes for 24 h, followed by addition of OVA SIINFEKL as a model antigen and spleen-derived OT-I CTLs for another 4 days. These T cells specifically recognize the OVA SIINFEKL peptide, resulting in a model of antigen-specific CTL activation in the tumor microenvironment. In this setting, mPGES-1−/− monocyte-derived tumor spheroid-infiltrating macrophages indeed expressed higher CD80, but not CD86, levels compared to wildtype macrophages (Figure 7A,B). These data corroborated our findings in the PyMT model. Spheroid-infiltrating OT-I cells displayed higher rates of proliferation (Figure 7C,D) and GrB expression (Figure 7E) when spheroids contained mPGES-1−/− monocyte-derived macrophages compared to WT macrophages. These data support the notion that reduced tumor growth in mPGES-1−/− PyMT mice was due to enhanced immune control. Importantly, infiltration of pre-activated WT or mPGES-1−/− spleen CTLs did not affect T cell proliferation or GrB expression (Figure 7F,G). These novel data demonstrate that mPGES-1-deficiency does not affect basic CTL function. Thus, a direct impact of mPGES-1-deficiency on CTL function in PyMT tumors was unlikely contributing to the phenotype of mPGES-1−/− PyMT mice. We conclude that mPGES-1−/− TAMs support CTL activation. This might be an important mechanism in restricting tumor occurrence in mPGES-1−/− PyMT mice.

Bottom Line: Pharmacological mPGES-1 inhibition increased CD80 expression, whereas addition of PGE2, a prostaglandin E2 receptor 2 (EP2) agonist, or activation of signaling downstream of EP2 reduced CD80 expression.Genetic ablation of mPGES-1 resulted in markedly reduced tumor growth in PyMT mice.In conclusion, mPGES-1 inhibition elevates CD80 expression by tumor-associated phagocytes to restrict tumor growth.

View Article: PubMed Central - PubMed

Affiliation: Institute of Biochemistry I, Faculty of Medicine, Goethe-University Frankfurt, Frankfurt, Germany.

ABSTRACT
Prostaglandin E2 (PGE2) favors multiple aspects of tumor development and immune evasion. Therefore, microsomal prostaglandin E synthase (mPGES-1/-2), is a potential target for cancer therapy. We explored whether inhibiting mPGES-1 in human and mouse models of breast cancer affects tumor-associated immunity. A new model of breast tumor spheroid killing by human PBMCs was developed. In this model, tumor killing required CD80 expression by tumor-associated phagocytes to trigger cytotoxic T cell activation. Pharmacological mPGES-1 inhibition increased CD80 expression, whereas addition of PGE2, a prostaglandin E2 receptor 2 (EP2) agonist, or activation of signaling downstream of EP2 reduced CD80 expression. Genetic ablation of mPGES-1 resulted in markedly reduced tumor growth in PyMT mice. Macrophages of mPGES-1(-/-) PyMT mice indeed expressed elevated levels of CD80 compared to their wildtype counterparts. CD80 expression in tumor-spheroid infiltrating mPGES-1(-/-) macrophages translated into antigen-specific cytotoxic T cell activation. In conclusion, mPGES-1 inhibition elevates CD80 expression by tumor-associated phagocytes to restrict tumor growth. We propose that mPGES-1 inhibition in combination with immune cell activation might be part of a therapeutic strategy to overcome the immunosuppressive tumor microenvironment.

No MeSH data available.


Related in: MedlinePlus