Metastatic cells feed off a complement.

Abstract

Cancer Cancer patients with metastases in the cerebrospinal fluid (CSF) have a poor prognosis. How cancer cells survive in the CSF has been an enigma because this microenvironment is devoid of mitogens and nutrients required for cell growth. Studying mice and patient samples, Boire et al. show that cancer cells metastasizing to the CSF overexpress a protein called complement component 3 (C3). C3 activates a specific receptor in the choroid plexus epithelium, a barrier system in the brain that prevents cells and molecules in the blood from entering the CSF. This activation disrupts the blood-CSF barrier, allowing circulating growth factors into the CSF. A drug that blocks this activation suppressed metastasis to the CSF in mice. Cell 168 , 1101 (2017).