Effects of cholinergic compounds and TNF-alpha on human erythroleukemia K562 cell proliferation and caspase expression

Objective: The purpose of this study was to investigate if stimulating auto-paracrine muscarinic receptor signalling pathway could change human erythroleukemia K562 cell proliferation and caspase 3, 8 and 9 expression levels. To better understand the role of muscarinic receptors in cell signalling mechanism, we investigated the effects of several compounds on human erythroleukemia K562 cell proliferation and caspase 3, 8 and 9 expression. These compounds were M3 muscarinic receptor agonist, pilocarpine, proinflammatory cytokine, tumor necrosis factor (TNF)-alpha, and the wortmannin which is a phosphoinositide 3-kinase inhibitor. Materials and Methods: Cell proliferation and cell viability were evaluated by the trypan blue exclusion test and 5-Bromo-2- deoxy-uridine (BrdU) Labelling and Detection Kits. Caspase 3, 8 and 9 expression levels were determined by immunoblot analysis. Results: Both pilocarpine and TNF-alpha caused a small increase in human erythroleukemia K562 cell proliferation. However, when all the compounds were treated together, proliferation of human erythroleukemia K562 cells increased significantly when compared to untreated control cells. TNF-alpha and wortmannin treatment increased caspase 3 and caspase 8 expression patterns significantly in human erythroleukemia K562 cells. TNF-alpha and wortmannin treatment increased caspase 9 expression level (P>0.05) but it was not significant. Conclusion: These findings partly demonstrated that M 3 muscarinic receptor mediated an increase in K562 cell proliferation. Pilocarpine prevented TNF-alpha and wortmannin induced caspase 3 and 8 expression and indirectly showed apoptosis in human erythroleukemia K562 cells