Patient-derived glioblastoma neurosphere cultures differentially express nicotinic acetylcholine receptors depending on ambient choline

Glioblastoma multiforme (GBM) is the most aggressive type of brain cancer with a poor prognosis. GBM cells, developing in the environment of neural tissue, often exploit neurotransmitters and their receptors to promote their growth and invasion. Nicotinic acetylcholine receptors (nAChRs) play a crucial role in the central nervous system signal transmission, are widely represented in the brain, the GBM cells expressing several subtypes of nAChRs which are suggested to transmit signals from neurons, thus promoting tumor invasion and growth. Functional 1*, 7 and 9 nAChRs are demonstrated on several patient-derived GBM neurosphere cultures and U87MG cell line using neurotoxins and fluorescent calcium assay. Selective 1*, 7 and 9 nAChR antagonists stimulated cell growth in presence of nicotinic agonists. Choline, normally present in blood, is capable of activating 1*, 7 and 9 nAChR subtypes, mediates the antagonists influence on cell proliferation. Several cultivating conditions have been shown to directly change sensitivity of primary GBM lines to nAChR ligands. Thus, results of in vitro testing of nAChR ligands on GBM lines should be interpreted and reviewed in cell culture conditions-aware manner.