Metabolism of primary colorectal tumor facilitate MDSC infiltration in pre-metastatic liver
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ABSTRACT: Through an integrated transcriptome analysis of orthotopic colorectal cancer tumor-bearing mice and sham-operation mice, we showed the distinct immune microenvironment of pre-metastatic liver and identified MDSCs as the dominated cell type mediating pre-metastatic niche formation. MDSCs instead of other immune cell types were highly infiltrated in the pre-metastatic liver when compared with normal liver. Notably, immunosuppressive factors released by MDSCs such as HIF1α, iNOS, TGFβ were significantly up-regulated in the pre-metastatic liver. Increasing immune checkpoint molecules expression also reflected an immunosuppressive condition of pre-metastatic liver. The primary tumor may induce MDSCs accumulation via metabolic mechanism including glycolysis/gluconeogenesis, HIF-1 signaling pathway, and CCL28 chemokine axis. This study depicts the immune cell landscape of pre-metastatic cancer and primary CRC tumor, and provides insights into how MDSCs reshape the pre-metastatic niche facilitating circulating cancer cells colonization.
Project description:Myeloid Derived Suppressor Cells (MDSCs) promote immunosuppressive activities in the tumor microenvironment (TME), resulting in increased tumor burden and diminishing the anti-tumor response of immunotherapies. While primary and metastatic tumors are typically the focal points of therapeutic development, the immune cells of the TME are uniquely programmed by the tissue of the metastatic site. In particular, MDSCs are programmed uniquely within different organs in the context of tumor progression. Given that MDSC plasticity is shaped by the surrounding environment, the proteome of MDSCs from different metastatic sites are hypothesized to be unique. A bottom-up proteomics approach using Sequential Window Acquisition of All Theoretical Mass Spectra (SWATH-MS) was used to quantify the proteome of CD11b+ cells derived from murine liver metastases (LM) and lung metastases (LuM). A comparative proteomics workflow was employed to compare MDSC proteins from LuM (LuM-MDSC) and LM (LM-MDSC) while also elucidating common signaling pathways, protein function, and possible drug-protein interactions.
Project description:Mortality from breast cancer is almost exclusively a result of tumor metastasis and resistance to therapy and therefore understanding the underlying mechanisms is an urgent challenge. Chemotherapy, routinely used to treat breast cancer, induces extensive tissue damage, eliciting an inflammatory response that may hinder efficacy and promote metastatic relapse. Here we show that systemic treatment with doxorubicin, but not cisplatin, following resection of a triple-negative breast tumor induced the expression of complement factors in lung fibroblasts and modulated an immunosuppressive metastatic niche that supported lung metastasis. CAF-derived complement signaling mediated the recruitment of myeloid-derived suppressor cells (MDSCs) to the metastatic niche, thus promoting T cell dysfunction. Pharmacological targeting of complement signaling in combination with chemotherapy alleviated immune dysregulation and attenuated lung metastasis. Our findings suggest that combining cytotoxic treatment with blockade of complement signaling in triple-negative breast cancer patients may attenuate the adverse effects of chemotherapy, thus offering a promising approach for clinical use.
Project description:Mortality from breast cancer is almost exclusively a result of tumor metastasis and resistance to therapy and therefore understanding the underlying mechanisms is an urgent challenge. Chemotherapy, routinely used to treat breast cancer, induces extensive tissue damage, eliciting an inflammatory response that may hinder efficacy and promote metastatic relapse. Here we show that systemic treatment with chemotherapy following resection of a triple-negative breast tumor induced the expression of complement factors in lung fibroblasts and modulated an immunosuppressive metastatic niche that supported lung metastasis. CAF-derived complement signaling mediated the recruitment of myeloid-derived suppressor cells (MDSCs) to the metastatic niche, thus promoting T cell dysfunction. Functionally, we show that pharmacological targeting of complement signaling in combination with chemotherapy alleviated immune dysregulation and attenuated lung metastasis. Our findings suggest that combining cytotoxic treatment with blockade of complement signaling in triple-negative breast cancer patients may attenuate the adverse effects of chemotherapy, thus offering a promising approach for clinical use.
Project description:Myeloid-derived suppressor cells (MDSCs) are highly immunosuppressive myeloid cells, which increase in cancer patients. The molecular mechanism behind their generation and function is unclear. Whereas granulocytic-MDSCs correlate with poor overall survival in breast cancer, the presence and relevance of monocytic-MDSCs (Mo-MDSCs) is unknown. Here we report for the first time an enrichment of functional blood Mo-MDSCs in breast cancer patients before they acquire a typical Mo-MDSC surface phenotype. A clear population of Mo-MDSCs with the typical cell surface phenotype (CD14+HLA-DRlow/-Co-receptorlow/-) increased significantly first during disease progression and correlated to metastasis to lymph nodes and visceral organs. Furthermore, monocytes, comprising the Mo-MDSC population, from patients with metastatic breast cancer resemble the reprogrammed immunosuppressive monocytes in patients with severe infections, both by their surface and functional phenotype but also at their molecular gene expression profile. Our data suggest that monitoring the Mo-MDSC levels in breast cancer patients may represent a novel and simple biomarker for assessing disease progression. Peripheral blood monocytes were isolated using magnetic cell sorting from 4 patients with metastatic breast cancer, 3 healthy controls, 3 patients with sepsis and 3 patients with active tuberculosis were immediately frozen at -80C in TRIZOL.
Project description:Myeloid-derived suppressor cells (MDSCs) are increased by tumor-derived factors and suppress anti-tumor immunity. MDSCs obtained at a late time point after tumor injection had stronger suppressive activity than MDSCs obtained at an early time point, as measured by T cell proliferation assays. To find factors in MDSCs that change during tumor growth, we analyzed gene expression profiles from MDSCs at different time points after tumor injection. We found that immune response-related genes were down-regulated, but pro-tumor function-related genes were up-regulated in both Mo-MDSCs and PMN-MDSCs at the late time point. Among differentially expressed genes, FK506 binding protein 51 (FKBP51), which is a member of the immunophilin protein family and plays a role in immunoregulation, was increased in the Mo- and PMN-MDSCs isolated from the late time points. Experiments using siRNA and a chemical inhibitor of FKBP51 revealed that FKBP51 contributes to the regulation of the suppressive function of MDSCs by increasing iNOS, ARG1, and ROS levels and enhancing NF-kappaB activity. Collectively, our data suggest that FKBP51 is a novel molecule that can be targeted to regulate the immunosuppressive function of MDSCs. To identify the factors that licensed MDSCs to be more suppressive as tumors grow, we analyzed gene expression profiles in the two subsets of MDSCs at different time points (3wks, 6wks) during tumor progression. CD11b+Ly-6C(high)Ly-6G(low) Mo-MDSCs and CD11b+Ly-6C(low)Ly-6G(high) PMN-MDSCs were sorted from pooled spleens of naïve mice and Her-2/CT26 tumor-bearing mice. Total RNA was purified and gene expression was analyzed by the Affymetrix GeneChip® Mouse Gene 1.0 ST Array.
Project description:To identify the differences in the MDSC population in the tumor verus pre-metastatic niche site, we performed RNA sequencing of isolated CD11b+ Ly6G+ MDSCs and analyzed the differentially expressed genes in PMN-MDSCs isolated from MOC2 tumors and corresponding lung tissues from the same mice To compare the MDSC RNA-level expression with neutrophil expression, a public mouse neutrophil microarray dataset was used (GSE60336). Our MDSC RNA-seq and the public mouse neutrophil data sets were merged using COMBAT55. DEGs for three groups (MDSC lung, MDSC tumor and neutrophil) were calculated using SAM56 multiple class comparison with false discovery rate smaller than 0.05. A total of 5 samples were generated.
Project description:Background: Metastasis is a leading cause of cancer-related deaths, with the liver being the most frequent site of metastasis in colorectal cancer. Previous studies have predominantly focused on the influence of the primary tumor itself on metastasis, with relatively limited research examining the changes within target organs. Methods: Using an orthotopic mouse model of colorectal cancer, single-cell sequencing was employed to profile the transcriptomic landscape of pre-metastatic and metastatic livers. The analysis focused on identifying cellular and molecular changes within the hepatic microenvironment, with particular emphasis on inflammatory pathways and immune cell populations. Results: A neutrophil subpopulation with high Prok2 expression was identified, showing elevated levels in the pre-metastatic and metastatic liver. Increased infiltration of Prok2⁺ neutrophils correlated with poor prognosis in liver metastatic colorectal cancer patients. In the liver macro-metastatic niche (MMN), these neutrophils showed high App and Cd274 (PD-L1) expression, suppressing macrophage phagocytosis and promoting T-cell exhaustion. Conclusion: A Prok2⁺ neutrophil subpopulation infiltrated both pre-metastatic and macro-metastatic liver environments, potentially driving immunosuppression through macrophage inhibition and T-cell exhaustion. Targeting Prok2⁺ neutrophils could represent a novel therapeutic strategy for preventing liver metastasis in colorectal cancer patients.
Project description:Myeloid-derived suppressor cells (MDSCs), which accumulate in tumor bearers, are known to suppress anti-tumor immunity and thus promote tumor progression. MDSCs are considered a major cause of resistance against immune checkpoint inhibitors in patients with cancer. Therefore, MDSCs are potential targets in cancer immunotherapy. In this study, we modified an in vitro method of MDSC differentiation. Upon stimulating bone marrow (BM) cells with granulocyte-macrophage colony-stimulating factor in vitro, we obtained both lymphocyte antigen 6G positive (Ly-6G+) and negative (Ly-6G−) MDSCs (collectively, hereafter referred to as conventional MDSCs), which were non-immunosuppressive and immunosuppressive, respectively. We then found that MDSCs differentiated from Ly-6G− BM (hereafter called 6G− BM-MDSC) suppressed T-cell proliferation more strongly than conventional MDSCs, whereas the cells differentiated from Ly-6G+ BM (hereafter called 6G+ BM-MDSC) were non-immunosuppressive. In line with this, conventional MDSCs or 6G− BM-MDSC, but not 6G+ BM-MDSC, promoted tumor progression in tumor-bearing mice. Moreover, we identified that activated glutathione metabolism was responsible for the enhanced immunosuppressive ability of 6G− BM-MDSC. Finally, we showed that Ly-6G+ cells in 6G− BM-MDSC, which exhibited weak immunosuppression, expressed higher levels of Cybb mRNA, an immunosuppressive gene of MDSCs, than 6G+ BM-MDSC. Together, these data suggest that the depletion of Ly-6G+ cells from the BM cells leads to differentiation of immunosuppressive Ly-6G+ MDSCs. In summary, we propose a better method for MDSC differentiation in vitro. Moreover, our findings contribute to the understanding of MDSC subpopulations and provide a basis for further research on MDSCs.
Project description:Immunosuppression plays a crucial role in the development of cancer which remains a major cause of mortality in kidney transplant recipients. Cancer Exosomes (Exos) are extracellular vesicles described as modulators of tumor invasion and metastasis. This paper describes the effect of RAPA and CsA, two immunosuppressive drugs with different oncogenic proprieties, in Exos of colorectal cancer (CRC) cell lines. RAPA induces an increased Exos production and an overexpression of miR-6127, miR-6746-5p, and miR-6787-5p in Exos from a metastatic cell line. These miRNAs produce a significant down-regulation of epigenetic genes involved in cell cycle, chromatin and DNA regulation pre-metastatic niche. Our results describe a potential mechanism by RAPA in modulating pre-metastatic niche in post-transplant metastatic CRC through these exosomal miRNAs.
Project description:Immunosuppression plays a crucial role in the development of cancer which remains a major cause of mortality in kidney transplant recipients. Cancer Exosomes (Exos) are extracellular vesicles described as modulators of tumor invasion and metastasis. This paper describes the effect of RAPA and CsA, two immunosuppressive drugs with different oncogenic proprieties, in Exos of colorectal cancer (CRC) cell lines. RAPA induces an increased Exos production and an overexpression of miR-6127, miR-6746-5p, and miR-6787-5p in Exos from a metastatic cell line. These miRNAs produce a significant down-regulation of epigenetic genes involved in cell cycle, chromatin and DNA regulation pre-metastatic niche. Our results describe a potential mechanism by RAPA in modulating pre-metastatic niche in post-transplant metastatic CRC through these exosomal miRNAs.