Cancer-associated differences in the acetylcholinesterase activity in bronchial aspirates of lung cancer patients
Résumé
In non-neuronal contexts, acetylcholine is thought to be involved in the regulation of vital cell functions such as proliferation, differentiation, apoptosis and cell-cell interaction. In airways most cells express the non-neuronal cholinergic system each containing a specific set of components required for synthesis, signal transduction and acetylcholine hydrolysis. Our aim was determine the expression of cholinergic system components in bronchial aspirates from controls and lung cancer patients. We conducted an analysis of cholinergic components in stored soluble and cellular fraction of bronchial aspirates from non-cancerous patients and diagnosed lung cancer patients. This study presents data proving that the fluid secreted by human lung cells contains enough acetylcholinesterase activity to control acetylcholine level. Thus, these data demonstrate that: (a) Acetylcholinesterase activity is significantly lower in aspirates from squamous cell carcinomas; (b) The molecular distribution of acetylcholinesterase in both bronchial cells and fluids consisted of amphiphilic monomers and dimers; (c) choline acetyltransferase, nicotinic receptors and cholinesterases are expressed in cultured human lung cells, as demonstrated by RT-PCR. It appears that the non-neuronal cholinergic system is involved in lung physiology and lung cancer. The physiological consequences of the presence of non-neuronal ACh will depend on the particular cholinergic signalling network of each cell type. Clarifying the pathophysiological actions of acetylcholine remains an essential task and warrants further investigation.
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