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Phosphoproteomics identify arachidonic-acid-regulated signal transduction pathways modulating macrophage functions in ovarian cancer

ABSTRACT: Arachidonic acid (AA) is a polyunsaturated fatty acid present at high concentrations in the ovarian cancer (OC) microenvironment and is associated with poor clinical outcome. In the present study, we elucidate a potential link between AA and pro-tumorigenic macrophage polarization. Methods: AA-triggered signal transduction was studied in primary monocyte-derived macrophages (MDMs) by phosphoproteomics, transcriptional profiling, measurement of intracellular Ca2+ accumulation and reactive oxygen species production in conjunction with bioinformatic analyses. Functional effects were investigated by actin filament staining, quantification of macropinocytosis and analysis of extracellular vesicle release. Results: We identified the ASK1 - p38 (MAPK13/14) axis as a central constituent of signal transduction pathways triggered by non-metabolized AA. This pathway was induced by the Ca2+-triggered activation of calmodulin kinase II, and to a minor extent by ROS generation in a subset of donors. Activated p38 in turn was linked to a transcriptional stress response associated with a poor relapse-free survival. Consistent with the phosphorylation of the p38 substrate HSP27 and the (de)phosphorylation of multiple regulators of Rho family GTPases, AA impaired actin filament organization and inhibited actin-driven macropinocytosis. AA also affected the phosphorylation of proteins regulating vesicle biogenesis, and consistently, AA enhanced the release of tetraspanin-containing exosomes. Finally, we identified phospholipase A2 Group 2A (PLA2G2A) as the clinically most relevant enzyme producing extracellular AA, providing further potentially theranostic options. Conclusion: Our results suggest that AA contributes to an unfavorable clinical outcome of OC by promoting the pro-tumorigenic phenotype of tumor-associated macrophages. Besides critical AA-regulated signal transduction proteins identified in the present study, PLA2G2A might represent a potential prognostic tool and therapeutic target to interfere with OC progression.

INSTRUMENT(S): Q Exactive

ORGANISM(S): Homo Sapiens (human)

TISSUE(S): Peritoneal Macrophage, Macrophage

DISEASE(S): Malignant Neoplasm Of Ovary

SUBMITTER: Johannes Graumann

LAB HEAD: Rolf Müller

PROVIDER: PXD021038 | Pride | 2020-10-05

REPOSITORIES: Pride

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Phosphoproteomics identify arachidonic-acid-regulated signal transduction pathways modulating macrophage functions with implications for ovarian cancer.

Dietze Raimund R Hammoud Mohamad K MK Gómez-Serrano María M Unger Annika A Bieringer Tim T Finkernagel Florian F Sokol Anna M AM Nist Andrea A Stiewe Thorsten T Reinartz Silke S Ponath Viviane V Preußer Christian C von Strandmann Elke Pogge EP Müller-Brüsselbach Sabine S Graumann Johannes J Müller Rolf R

Theranostics 20210101 3

Arachidonic acid (AA) is a polyunsaturated fatty acid present at high concentrations in the ovarian cancer (OC) microenvironment and associated with a poor clinical outcome. In the present study, we have unraveled a potential link between AA and macrophage functions. <b>Methods:</b> AA-triggered signal transduction was studied in primary monocyte-derived macrophages (MDMs) by phosphoproteomics, transcriptional profiling, measurement of intracellular Ca<sup>2+</sup> accumulation and reactive oxyg ...[more]

PMID: 33391540

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Project description:Progression and relapse-free survival of ovarian carcinoma are associated with the abundance of immunosuppressed CD163highCD206high tumor-associated macrophages (TAMs) and high levels of polyunsaturated fatty acids (PUFAs), in particular arachidonic acid (AA), in the tumor microenvironment. In the present study, we have investigated whether both associations are functionally linked. Methods: The effect of PUFAs on cytokine-mediated pro-inflammatory signal transduction was studied in primary monocyte-derived macrophages (MDMs) by transcriptomics, bioinformatics, phosphoprotein analysis of signal transduction proteins and MS-based proteomics of lipid rafts. Results: Pathway analysis of transcriptional profiles revealed that high CD163 and CD206/MRC1 expression in TAMs is strongly associated with an inhibition of cytokine-triggered signal transduction. This is mirrored by an impairment of the transcriptional response to interferon-beta (IFNbeta), IFNgamma and IL-6 in monocyte-derived macrophages (MDMs) by AA. This AA-mediated inhibition of pro-inflammatory signaling is caused by dysfunctions of the cognate receptors, as indicated by the inhibition by PUFAs of JAK1, JAK2, STAT1 and STAT3 phosphorylation, with the strongest inhibitory effects exerted by AA and its non-metabolizable analog ETYA. AA/ETYA treatment of MDMs results in altered composition of lipid rafts, including reduced amounts of the interferon receptor IFNAR1, STAT1 and other immune-regulatory proteins. The AA-mediated inhibition of IFN-triggered STAT1 phosphorylation was reversed by water-soluble cholesterol, known to prevent the perturbation of lipid raft structure by PUFAs. Conclusion: Our data suggest that AA, and to a lesser degree other PUFAs, impair pro-inflammatory signaling in macrophages, at least in part by altering the structure of lipid rafts, and thereby contribute to the reeducation of tumor-associated macrophages. Our findings also suggest that the pharmacologic restoration of lipid raft functions in TAM may be a promising strategy for the development of new therapeutic approaches.

Project description:The mitogen-activated protein kinase (MAPK) p38 pathway is reported to regulate macrophage responses to lipopolysaccharide (LPS) at least partly via the phosphorylation of the mRNA-destabilizing factor tristetraprolin (TTP). LPS-activated MAPK p38 phosphorylates and activates the downstream kinase MAPK-activated protein kinase 2 (MK2), which then phosphorylates serines 52 and 178 of TTP, resulting in loss of mRNA-destabilizing activity. As a consequence, mRNAs that contain binding sites for TTP are stabilized in a manner that is acutely sensitive to the activity of the MAPK p38 pathway. Dual specificity phosphatase 1 (DUSP1) dephosphorylates and inactivates MAPK p38. Dusp1-/- macrophages overexpress a number of pro-inflammatory mediators, but their genome-wide responses to LPS have not yet been described in detail. Dusp1-/- mice are exceptionally sensitive to a wide variety of inflammatory challenges, including experimental models of endotoxemia or sepsis. It has been suggested (but not yet proven) that DUSP1 controls the inflammatory response of macrophages in part via the regulation of MAPK p38 activity and TTP phosphorylation status. We generated a mouse knock-in strain, in which codons 52 and 178 of the endogenous Zfp36 gene (which encodes TTP) were mutated to alanine codons. The mutation gives rise to a constitutively active form of TTP, which cannot be inactivated via the p38 MAPK pathway. The Zfp36aa/aa strain was back-crossed against C57/BL6 for > 10 generations. We also generated a double-targeted strain in which the Zfp36 mutation was combined with disruption of the Dusp1 gene. This expression array describes LPS responses of primary mouse bone marrow-derived macrophages of four genotypes, and closely matched genetic background: wild type (Dusp1+/+ : Zfp36+/+); TTP mutant (Zfp36aa/aa); DUSP1 knock out (Dusp1-/-); and double targeted (Dusp1-/- : Zfp36aa/aa). The data provide a comprehensive picture of the impact of Dusp1 deletion or TTP mutation on the responses of primary macrophages to LPS. They also demonstrate that the excessive inflammatory responses of Dusp1-/- macrophages are largely a consequence of the phosphorylation and inactivation of TTP. Genome wide expression profiles of wild type, Dusp1-/-, Zfp36aa/aa and Dusp1-/-/Zfp36aa/aa M-CSF derived macrophages, stimulated with LPS for 1 or 4 hours

Dataset Information

Phosphoproteomics identify arachidonic-acid-regulated signal transduction pathways modulating macrophage functions in ovarian cancer

Publications

Phosphoproteomics identify arachidonic-acid-regulated signal transduction pathways modulating macrophage functions with implications for ovarian cancer.

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