Neuronal exposure induces neurotransmitter signaling and synaptic mediators in tumors early in brain metastasis.

Background: Brain metastases (BM) are responsible for neurological decline and poor overall survival. Although the pro-metastatic roles of glial cells, and the acquisition of neuronal attributes in established BM tumors have been described, there are no studies that investigate the initial interplay between neurons and brain-seeking tumor cells. The aim of this study was to characterize early tumor-neuron interactions and the induced CNS-adaptive changes in tumor cells prior to macro-colonization.

Cortisol promotes breast-to-brain metastasis through the blood-cerebrospinal fluid barrier.

Background: Elevated basal cortisol levels are present in women with primary and metastatic breast cancer. Although cortisol's potential role in breast-to-brain metastasis has yet to be sufficiently studied, prior evidence indicates that it functions as a double-edged sword-cortisol induces breast cancer metastasis in vivo, but strengthens the blood-brain-barrier (BBB) to protect the brain from microbes and peripheral immune cells.

Aims: In this study, we provide a novel examination on whether cortisol's role in tumor invasiveness eclipses its supporting role in strengthening the CNS barriers.