Neutrophil Extracellular Traps in Breast Cancer and Beyond: Current Perspectives on NET Stimuli, Thrombosis and Metastasis, and Clinical Utility for Diagnosis and Treatment

Abstract The formation of neutrophil extracellular traps (NETs), known as NETosis, was first observed as a novel immune response to bacterial infection, but has since been found to occur abnormally in a variety of other inflammatory disease states including cancer. Breast cancer is the most commonly diagnosed malignancy in women. In breast cancer, NETosis has been linked to increased disease progression, metastasis, and complications such as venous thromboembolism. NET-targeted therapies have shown success in preclinical cancer models and may prove valuable clinical targets in slowing or halting tumor progression in breast cancer patients. We will briefly outline the mechanisms by which NETs may form in the tumor microenvironment and circulation, including the crosstalk between neutrophils, tumor cells, endothelial cells, and platelets as well as the role of cancer-associated extracellular vesicles in modulating neutrophil behavior and NET extrusion. The prognostic implications of cancer-associated NETosis will be explored in addition to development of novel therapeutics aimed at targeting NET interactions to improve outcomes in patients with breast cancer

Channelrhodopsin-2-assisted circuit mapping of long-range callosal projections

The functions of cortical areas depend on their inputs and outputs, but the detailed circuits made by long- range projections are unknown. We show that the light- gated channel channelrhodopsin- 2 ( ChR2) is delivered to axons in pyramidal neurons in vivo. In brain slices from ChR2- expressing mice, photostimulation of ChR2- positive axons can be transduced reliably into single action potentials. Combining photostimulation with whole- cell recordings of synaptic currents makes it possible to map circuits between presynaptic neurons, defined by ChR2 expression, and postsynaptic neurons, defined by targeted patching. We applied this technique, ChR2- assisted circuit mapping ( CRACM), to map long- range callosal projections from layer ( L) 2/3 of the somatosensory cortex. L2/3 axons connect with neurons in L5, L2/3 and L6, but not L4, in both ipsilateral and contralateral cortex. In both hemispheres the L2/3- to- L5 projection is stronger than the L2/3- to- L2/3 projection. Our results suggest that laminar specificity may be identical for local and longrange cortical projections