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CXCR2-expressing myeloid-derived suppressor cells are essential to promote colitis-associated tumorigenesis.

ABSTRACT: A large body of evidence indicates that chronic inflammation is one of several key risk factors for cancer initiation, progression, and metastasis. However, the underlying mechanisms responsible for the contribution of inflammation and inflammatory mediators to cancer remain elusive. Here, we present genetic evidence that loss of CXCR2 dramatically suppresses chronic colonic inflammation and colitis-associated tumorigenesis through inhibiting infiltration of myeloid-derived suppressor cells (MDSCs) into colonic mucosa and tumors in a mouse model of colitis-associated cancer. CXCR2 ligands were elevated in inflamed colonic mucosa and tumors and induced MDSC chemotaxis. Adoptive transfer of wild-type MDSCs into Cxcr2(-/-) mice restored AOM/DSS-induced tumor progression. MDSCs accelerated tumor growth by inhibiting CD8(+) T cell cytotoxic activity.

SUBMITTER: Katoh H

PROVIDER: S-EPMC3928012 | biostudies-literature | 2013 Nov

REPOSITORIES: biostudies-literature

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CXCR2-expressing myeloid-derived suppressor cells are essential to promote colitis-associated tumorigenesis.

Katoh Hiroshi H Wang Dingzhi D Daikoku Takiko T Sun Haiyan H Dey Sudhansu K SK Dubois Raymond N RN

Cancer cell 20131101 5

A large body of evidence indicates that chronic inflammation is one of several key risk factors for cancer initiation, progression, and metastasis. However, the underlying mechanisms responsible for the contribution of inflammation and inflammatory mediators to cancer remain elusive. Here, we present genetic evidence that loss of CXCR2 dramatically suppresses chronic colonic inflammation and colitis-associated tumorigenesis through inhibiting infiltration of myeloid-derived suppressor cells (MDS ...[more]

PMID: 24229710

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Project description:BackgroundEmerging evidences suggest that aberrant metabolites contributes to the immunosuppressive microenvironment that leads to cancer immune evasion. Among tumor immunosuppressive cells, myeloid-derived suppressor cells (MDSCs) are pathologically activated and extremely immunosuppressive, which are closely associated with poor clinical outcomes of cancer patients. However, the correlation between MDSCs mediated immunosuppression and particular cancer metabolism remained elusive.MethodsSpontaneous lung adenocarcinoma and subcutaneous mouse tumor models, gas chromatography-mass spectrometry (GC-MS) and immunofluorescence assay of patient-derived lung adenocarcinoma tissues, and flow cytometry, RNA sequencing and Western blotting of immune cells, were utilized.ResultsMetabolite profiling revealed a significant accumulation of acetic acids in tumor tissues from both patients and mouse model, which contribute to immune suppression and cancer progression significantly through free fatty acid receptor 2 (FFAR2). Furthermore, FFAR2 is highly expressed in the myeloid-derived suppressor cells (MDSCs) from the tumor of lung adenocarcinoma (LUAD) patients which is greatly associated with poor prognosis. Surprisingly, whole or myeloid Ffar2 gene deletion markedly inhibited urethane-induced lung carcinogenesis and syngeneic tumor growth with reduced MDSCs and increased CD8+ T cell infiltration. Mechanistically, FFAR2 deficiency in MDSCs significantly reduced the expression of Arg1 through Gαq/Calcium/PPAR-γ axis, which eliminated T cell dysfunction through relieving L-Arginine consumption in tumor microenvironment. Therefore, replenishment of L-Arginine or inhibition to PPAR-γ restored acetic acids/FFAR2 mediated suppression to T cells significantly. Finally, FFAR2 inhibition overcame resistance to immune checkpoint blockade through enhancing the recruitment and cytotoxicity of tumor-infiltrating T cells.ConclusionAltogether, our results demonstrate that the acetic acids/FFAR2 axis enhances MDSCs mediated immunosuppression through Gαq/calcium/PPAR-γ/Arg1 signaling pathway, thus contributing to cancer progression. Therefore, FFAR2 may serve as a potential new target to eliminate pathologically activated MDSCs and reverse immunosuppressive tumor microenvironment, which has great potential in improving clinical outcomes of cancer immunotherapy.

Project description:BackgroundAccumulating evidence implicates that gut fungi are associated with the pathogenesis of colorectal cancer (CRC). Our previous study has revealed that Candida tropicalis (C. tropicalis) promotes colorectal tumorigenesis by enhancing immunosuppressive function of myeloid-derived suppressor cells (MDSCs) and increasing accumulation of MDSCs, but the underlying mechanisms remain unestablished.MethodsBone marrow-derived MDSCs were stimulated with C. tropicalis. RNA-sequencing analysis was performed to screen the differentially expressed genes. Quantitative real-time PCR and western blot were used to measure the expression of related proteins. Co-culture assay of MDSCs and CD8+ T cells was used to determine the immunosuppressive ability of MDSCs. Metabolomic analysis was conducted to detect metabolic reprogramming of MDSCs. Aerobic glycolysis of MDSCs was assessed by extracellular acidification rate (ECAR), glucose consumption and lactate production. A CAC mouse model was induced by AOM and DSS to determine the therapeutic action of TEPP-46. IHC and immunofluorescence were performed to examine the expression of PKM2, PKM2 (p-Y105) and iNOS in human CRC-infiltrated MDSCs.ResultsC. tropicalis facilitates immunosuppressive function of MDSCs by increasing the expression of iNOS, COX2 and NOX2, production of nitric oxide (NO) and reactive oxygen species (ROS). Mechanistically, C. tropicalis facilitates the immunosuppressive function of MDSCs through the C-type lectin receptors Dectin-3 and Syk. C. tropicalis-enhanced immunosuppressive function of MDSCs is further dependent on aerobic glycolysis. On the one hand, NO produced by MDSCs enhanced aerobic glycolysis in a positive feedback manner. On the other hand, C. tropicalis promotes p-Syk binding to PKM2, which results in PKM2 Tyr105 phosphorylation and PKM2 nuclear translocation in MDSCs. Nuclear PKM2 interacts with HIF-1α and subsequently upregulates the expression of HIF-1α target genes encoding glycolytic enzymes, GLUT1, HK2, PKM2, LDHA and PDK1, which are required for the C. tropicalis-induced aerobic glycolysis of MDSCs. Blockade of PKM2 nuclear translocation attenuates C. tropicalis-mediated colorectal tumorigenesis. The high expression of PKM2, PKM2 (p-Y105) and iNOS in CRC-infiltrated MDSCs correlates with the development of human CRC.ConclusionC. tropicalis enhances immunosuppressive function of MDSCs via Syk-PKM2-HIF-1α-glycolysis signaling axis, which drives CRC. Therefore, we identify the Syk-PKM2-HIF-1α-glycolysis signaling axis as a potential therapeutic target for CRC.

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CXCR2-expressing myeloid-derived suppressor cells are essential to promote colitis-associated tumorigenesis.

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CXCR2-expressing myeloid-derived suppressor cells are essential to promote colitis-associated tumorigenesis.

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