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CD47-dependent regulation of immune checkpoint gene ex-pression and MYCN mRNA splicing in murine CD8 and human Jurkat T cells

ABSTRACT: Elevated expression of CD47 in some cancers is associated with poor survival, related to its function as an innate immune checkpoint when expressed on tumors cells. In contrast, elevated CD47 ex-pression in cutaneous melanomas is associated with improved survival. Previous studies impli-cated protective functions of CD47 expressed by immune cells in the melanoma tumor microen-vironment. RNA sequencing analysis of responses induced by CD3 and CD28 engagement on wild type and CD47-deficient Jurkat T lymphoblast cells identified additional regulators of T cell func-tion that were also CD47-dependent in mouse CD8 T cells. MYCN mRNA expression was up-regulated in CD47-deficient cells but down-regulated in CD47-deficient cells following activa-tion. CD47 also regulated alternative splicing that produces two N-MYC isoforms. The CD47 ligand thrombospondin-1 inhibited expression of these MYCN mRNA isoforms as well as induction of the oncogenic decoy MYCN opposite strand (MYCNOS) noncoding RNA during T cell activation. Analysis of mRNA expression data for melanomas in The Cancer Genome Atlas identified signif-icant coexpression of MYCN with CD47 and known regulators of CD8 T cell function. Throm-bospondin-1 inhibited the induction of TIGIT, CD40LG and MCL1 mRNAs following T cell acti-vation in vitro. Increased mRNA expression of these T cell transcripts and of MYCN in melanomas was associated with improved overall survival.

ORGANISM(S): Homo sapiens

PROVIDER: GSE218256 | GEO | 2023/02/15

REPOSITORIES: GEO

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Project description:Intercellular communication is critical for integrating complex signals in multicellular eukaryotes. Vascular endothelial cells and T lymphocytes closely interact during the recirculation and trans-endothelial migration of T cells. In addition to direct cell-cell contact, we show that T cell derived extracellular vesicles can interact with endothelial cells and modulate their cellular functions. Thrombospondin-1 and its receptor CD47 are expressed on exosomes/ectosomes derived from T cells, and these extracellular vesicles are internalized and modulate signaling in both T cells and endothelial cells. Extracellular vesicles released from cells expressing or lacking CD47 differentially regulate activation of T cells induced by engaging the T cell receptor. Similarly, T cell-derived extracellular vesicles modulate endothelial cell responses to vascular endothelial growth factor and tube formation in a CD47-dependent manner. Uptake of T cell derived extracellular vesicles by recipient endothelial cells globally alters gene expression in a CD47-dependent manner. CD47 also regulates the mRNA content of extracellular vesicles in a manner consistent with some of the resulting alterations in target endothelial cell gene expression. Therefore, the thrombospondin-1 receptor CD47 directly or indirectly regulates intercellular communication mediated by the transfer of extracellular vesicles between vascular cells. Treatment with B6H12 antibody inhibited co-immunoprecipitation of EGFR with CD47 and inhibited EGF-induced EGFR tyrosine phosphorylation. B6H12 treatment of bCSC also suppressed asymmetric cell division and cell proliferation and up-regulated caspase 3/7 activity. Correspondingly, caspase-7 cleavage in human breast cancers correlated with CD47 expression. Our data shows that B6H12 specifically targets bCSCs but not differentiated cancer cells, and this CD47 signaling is independent of SIRPÎ±. Three replicates of each condition were generated. Three replicates of each MDA-231 attached cells (differentiated), MDA-231 in suspension cells (bCSC), MDA-231 in suspension cells (bCSC) treated with Control Antibody and MDA-231 in suspension cells (bCSC) treated with B6H12 Antibody.

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CD47-dependent regulation of immune checkpoint gene ex-pression and MYCN mRNA splicing in murine CD8 and human Jurkat T cells

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