Effects of carbachol on apoptosis in human chronic myelogenous leukemic K562 cell line

Abstract

Objectives: Muscarinic receptors mediate diverse actions ofacetylcholine in the central nervous system and in non-nervoustissues innervated by the parasympathetic nervous system.Our study aims to evaluate the potential association of theM3 muscarinic receptor with K562 cell proliferation and death.Materials and Methods: Cell proliferation was evaluatedby bromodeoxyuridine (BrDU) incorporation. To show early,late apoptosis and cell death, cells were labelled with AnnexinV, propidium iodide (PI) and analyzed by flow cytometry. Nuclearextracellular signal-regulated kinase (ERK/pERK) expressionwas measured by western blot analysis.Results: Treatment with carbachol (CCh) for 48h decreased cellnumber. Exposing K562 cells to CCh for 24h decreased the number ofearly apoptotic cells but did not change the number of late apoptotic andnecrotic cells. CCh treatment for 48h increased the number of necroticcells, but decreased the number of early and late apoptotic cells. Inresponse to CCh, nuclear ERK expression was increased and this effectwas reversed by 1,1-dimethyl-4-diphenylacetoxypiperidinium iodide(4DAMP). Nuclear pERK expression was decreased in CCh treatedcells, 4DAMP did not reverse the effect.Conclusion: Our data suggest that cholinergic agonist CChaffects cell proliferation in K562 cells not only through muscarinicreceptors but also through other cholinergic receptors.