Id1 suppresses anti-tumour immune responses and promotes tumour progression by impairing myeloid cell maturation

A central mechanism of tumour progression and metastasis involves the generation of an immunosuppressive ‘macroenvironment' mediated in part through tumour-secreted factors. Here we demonstrate that upregulation of the Inhibitor of Differentiation 1 (Id1), in response to tumour-derived factors, such as TGFβ, is responsible for the switch from dendritic cell (DC) differentiation to myeloid-derived suppressor cell expansion during tumour progression. Genetic inactivation of Id1 largely corrects the myeloid imbalance, whereas Id1 overexpression in the absence of tumour-derived factors re-creates it. Id1 overexpression leads to systemic immunosuppression by downregulation of key molecules involved in DC differentiation and suppression of CD8 T-cell proliferation, thus promoting primary tumour growth and metastatic progression. Furthermore, advanced melanoma patients have increased plasma TGFβ levels and express higher levels of ID1 in myeloid peripheral blood cells. This study reveals a critical role for Id1 in suppressing the anti-tumour immune response during tumour progression and metastasis.

Tumour progression is promoted by the generation of an immunosuppressive macroenvironment. Here, the authors demonstrate that the Inhibitor of Differentiation 1 promotes the switch from dendritic cell differentiation towards myeloid-derived suppressor cell expansion during tumour progression.

Abstract 1651: Profiling immune cells within the tumor microenvironment for optimal model selection for pre-clinical investigations

Infiltrating host immune cells can have a significant impact on the growth and outcome of many tumor types. Several leukocyte populations have been implicated in establishing an immune suppressive microenvironment (e.g. myeloid derived suppressor cells [MDSCs) and regulatory T cells [Treg cells]) and thus making it harder for anti-tumor immune effector cells to function (e.g. CD8 cytotoxic T cells). Immune-Mediated Therapy (IMT) is emerging as a key strategy for the treatment of cancer through by enhancing a patient's anti-tumor immune response. In order to maximise the potential of IMT strategies it is important to understand the immune status within the tumor microenvironment as well as systemically. Therefore, fully immune-competent preclinical models are valuable tools to enable the study of the immune system, both locally within the tumor and systemically, to understand the mechanism of action of IMT monotherapies and combination therapies in vivo. Consequently, we have profiled the immune status of a panel of syngeneic mouse tumor models to assist optimal model selection to aid these investigations. We developed multi-parameter flow cytometry techniques to identify specific immune subsets in both the tumor microenvironment and the periphery. These investigations revealed a number of tumor infiltrating immune cell end-points that can be used to correlate with response to IMT depending on the syngeneic model being used. For example, we observed differences in the MDSC and Treg cell populations across the models investigated, which will influence optimal model selection depending on the mechanism of action of the IMT being tested.

Citation Format: Andrew Leishman, Olivia Harris, Jane Coates Ulrichsen, James Harper, Amy Popple, Marianna Papaspyridonos, Geoff Williams, Stefanie Mullins, Viia Valge-Archer, Ross Stewart, Richard Sainson, Michelle Morrow, Robert Wilkinson. Profiling immune cells within the tumor microenvironment for optimal model selection for pre-clinical investigations. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1651. doi:10.1158/1538-7445.AM2014-1651

Abstract 1562: Choosing the right preclinical model for cancer immunotherapy: The “SyngenOmic” toolbox

Recent FDA approvals of ipilimumab and sipuleucel-T for the treatment of metastatic melanoma and castrate-resistant prostate cancer respectively have validated the approach to modulate the immune system for the clinical treatment of cancer. MedImmune Oncology, has an extensive pipeline and expertise in investigational Immune Mediated Therapy in Cancer (IMT-C) drugs (e.g. tremelimumab and MEDI4736), and is heavily invested in this novel era of cancer therapeutics. Pre-clinical assessment of the validity of potential IMT-C drugs can be enabled by the use of syngeneic tumours established in immuno-competent animals. MedImmune's pharmacology team has lead efforts to develop such models, to a point that a panel of 15 different validated syngeneic tumour types is available in house for studies to progress projects. The intention of selecting relevant models and of minimizing animal experimentation, reduces the number of models tested for each project, and allows for detailed genetic and proteomic characterization of treatment dependent effects within our models. Utilising both in vitro and in vivo approaches, we have generated transcriptomic and genomic data for our cell lines, the resulting implanted tumours and for the relevant lymphatic organs (draining lymph node and spleen). Using key proteomic/cell markers through IHC and FACS analysis, we are also evaluating the immune profile/status of our tumour bearing animals in parallel. Finally, in order to establish the disease relevance and prognostic value of our models we are analyzing our cell panel for the presence of somatic mutations in 50 genes previously implicated in human cancers. Once completed, the resulting dataset will hopefully help pre-clinical scientists to refine their in vivo plans and deliver more clinically-relevant pharmacology packages for the progression of cancer immunotherapy drug candidates.

Citation Format: James A. Harper, John Prime, Athula Herath, Jane Howell, Marianna Papaspyridonos, Amy Popple, Judith Anderton, Michelle Morrow, Arthur Lewis, Liz Henley, Matthew McCourt, Richard Sainson. Choosing the right preclinical model for cancer immunotherapy: The “SyngenOmic” toolbox. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1562. doi:10.1158/1538-7445.AM2013-1562

CCR2-mediated antiinflammatory effects of endothelial tetrahydrobiopterin inhibit vascular injury-induced accelerated atherosclerosis

BACKGROUND

Vascular injury results in loss of endothelial nitric oxide (NO), production of reactive oxygen species (ROS), and the initiation of an inflammatory response. Both NO and ROS modulate inflammation through redox-sensitive pathways. Tetrahydrobiopterin (BH4) is an essential cofactor for endothelial nitric oxide synthase (eNOS) that regulates enzymatic synthesis of either nitric oxide or ROS. We hypothesized that endothelial BH4 is an important regulator of inflammation and vascular remodeling.

METHODS AND RESULTS

Endothelium-targeted overexpression of GTP cyclohydrolase 1 (GCH), the rate limiting enzyme in BH4 synthesis, increased levels of tetrahydrobiopterin (BH4), reduced endothelial superoxide, improved eNOS coupling, and reduced vein graft atherosclerosis in transgenic GCH/ApoE-KO mice compared to ApoE-KO controls. Immunohistochemistry using anti-MAC-3 and MAC-1 antibody staining revealed a marked reduction in vein graft macrophage content, as did RT-PCR expression of macrophage marker CD68 mRNA levels in GCH/ApoE-KO mice. When we investigated the potential mediators of this reduction, we discovered that mRNA and protein levels of MCP-1 (CCL2) but not RANTES (CCL5) were significantly reduced in GCH/ApoE-KO aortic tissue. Consistent with this finding we found a decrease in CCR2-mediated, but not CCR5-mediated, chemotaxis in vascular tissue and plasma samples from GCH/ApoE-KO animals.

CONCLUSIONS

Increased endothelial BH4 reduces vein graft neointimal hyperplasia and atherosclerosis through a reduction in vascular inflammation. These findings highlight the importance of MCP-1/CCR2 signaling in the response to vascular injury and identify novel pathways linking endothelial BH4 to inflammation and vascular remodeling.

Chapter 11. The role of bone marrow-derived cells in tumor angiogenesis and metastatic progression

Tumor angiogenesis is orchestrated by a complex set of secreted factors and collaboration between many different cell types. This chapter discusses the role of tumor-secreted angiogenic factors that are responsible for the recruitment of bone marrow-derived cells (BMDCs) at tumor sites and their role in tumor angiogenesis and progression.

Novel candidate genes in unstable areas of human atherosclerotic plaques

OBJECTIVE

Comparison of gene expression in stable versus unstable atherosclerotic plaque may be confounded by interpatient variability. The aim of this study was to identify differences in gene expression between stable and unstable segments of plaque obtained from the same patient.

METHODS AND RESULTS

Human carotid endarterectomy specimens were segmented and macroscopically classified using a morphological classification system. Two analytical methods, an intraplaque and an interplaque analysis, revealed 170 and 1916 differentially expressed genes, respectively using Affymetrix gene chip analysis. A total of 115 genes were identified from both analyses. The differential expression of 27 genes was also confirmed using quantitative-polymerase chain reaction on a larger panel of samples. Eighteen of these genes have not been associated previously with plaque instability, including the metalloproteinase, ADAMDEC1 (approximately 37-fold), retinoic acid receptor responder-1 (approximately 5-fold), and cysteine protease legumain (approximately 3-fold). Matrix metalloproteinase-9 (MMP-9), cathepsin B, and a novel gene, legumain, a potential activator of MMPs and cathepsins, were also confirmed at the protein level.

CONCLUSIONS

The differential expression of 18 genes not previously associated with plaque rupture has been confirmed in stable and unstable regions of the same atherosclerotic plaque. These genes may represent novel targets for the treatment of unstable plaque or useful diagnostic markers of plaque instability.

A first-generation linkage disequilibrium map of human chromosome 22

DNA sequence variants in specific genes or regions of the human genome are responsible for a variety of phenotypes such as disease risk or variable drug response. These variants can be investigated directly, or through their non-random associations with neighbouring markers (called linkage disequilibrium (LD)). Here we report measurement of LD along the complete sequence of human chromosome 22. Duplicate genotyping and analysis of 1,504 markers in Centre d'Etude du Polymorphisme Humain (CEPH) reference families at a median spacing of 15 kilobases (kb) reveals a highly variable pattern of LD along the chromosome, in which extensive regions of nearly complete LD up to 804 kb in length are interspersed with regions of little or no detectable LD. The LD patterns are replicated in a panel of unrelated UK Caucasians. There is a strong correlation between high LD and low recombination frequency in the extant genetic map, suggesting that historical and contemporary recombination rates are similar. This study demonstrates the feasibility of developing genome-wide maps of LD.