Genetic and pharmacological targeting of nicotinic acetylcholine receptor action blocks tumor progression in mouse models of breast cancer

The alpha 7 nicotinic acetylcholine receptor has a functional role in myeloid immune cells in models of injury and infection, but a role in tumor associated immune cells has not been established. Here we focus on the role of CHRNA7 in myeloid immune cells in immune competent triple negative breast cancer mouse models. The purpose of our scRNAseq studies was to evaluate the role of CHRNA7 deletion on the in vivo immune cell transcriptional profile. We established primary cultures of bone marrow-derived myeloid cells following differentiation with M-CSF and IL-4, which yields a mix of macrophages and dendritic cells (BMDMs/BMDCs). Single-cell RNA sequencing of bone marrow–derived macrophages and dendritic cells (BMDMs/BMDCs) revealed that CHRNA7 knockout (KO) cells exhibit distinct transcriptional profiles compared to wild-type (WT), including reduced expression of inflammatory and leukocyte migration pathways and increased expression of stress and apoptotic signaling genes. CHRNA7KO cells upregulated hypoxia- and ubiquitination-related genes, while CHRNA7WT cells expressed higher levels of TNFα signaling and immune function markers. These results support a cell-intrinsic role for CHRNA7 in regulating immune gene expression. These results led us to perform further in vivo studies to assess the effect of a specific CHRNA7 agonist, AR-R17779 on immune cell activation, tumor burden, and metastasis.