Antibody-induced CD47 signaling suppresses triple-negative breast cancer stem cells

ABSTRACT: 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 SIRPα. Three replicates of each condition were generated.

ORGANISM(S): Homo sapiens

PROVIDER: GSE67966 | GEO | 2016/04/01

SECONDARY ACCESSION(S): PRJNA281386

REPOSITORIES: GEO