Potential antiproliferative and apoptotic effects of pilocarpine combined with TNF alpha in chronic myeloid leukemia cells.

Pilocarpine is a selective M1/M3 agonist of muscarinic acetylcholine receptor subtypes. Muscarinic acetylcholine receptors are G protein-coupled receptors. These receptors are different drug targets. The aim of the present work was to investigate the effect of pilocarpine on the expression of M3 muscarinic acetylcholine receptor, the AChE activity, IL-8 release response, and proliferation in K562 cells, via muscarinic receptor activation. Human chronic myeloid leukemic cell cultures were incubated with drugs. Proliferation assays were performed by BrdU assay. Expression of M3 muscarinic acetylcholine receptor and apoptosis proteins such as bcl, bax, cyt C, and caspases was assessed with the semiquantitative Western blotting method. Pilocarpine inhibits chronic myeloid cell proliferation and M3 muscarinic acetylcholine receptor protein expression. Pilocarpine increases caspase-8 and -9 expression levels, upregulating the proapoptotic protein Bax and downregulating the expression levels of the antiapoptotic protein Bcl-2. The apoptotic activity of pilocarpine is associated with an increase in AChE activity. M3 muscarinic acetylcholine receptors can activate multiple signal transduction systems and mediate inhibitory effects on chronic myeloid K562 cell proliferation depending on the presence of 1% FBS conditions. This apoptotic effect of pilocarpine may be due to the concentration of pilocarpine and the increase in AChE level. Our results suggest that inhibition of cell proliferation by inducing apoptosis of pilocarpine in K562 cells may be one of the targets. M3 selective agonist may have therapeutic potential in chronic myeloid leukemia.

Cross-talk of cholinergic and ß-adrenergic receptor signalling in chronic myeloid leukemia K562 cells.

In many studies on breast, skin and intestinal cancers, ß-adrenergic receptor antagonists have been shown to inhibit cell proliferation and angiogenesis and increase apoptosis in cancers. Carbachol inhibits chronic myeloid leukaemia K562 cell proliferation. Beta-blockers are known to inhibit cell progression. The aim of this study is to explain the mechanism of action of ß-adrenergic receptors agonists and antagonists on apoptosis in chronic myeloid leukaemia cells. We tried to determine the effect of combined treatment of ß-adrenergic and cholinergic drugs on adrenergic ß1 and ß2 gene expression, cell proliferation and apoptosis in chronic myeloid leukaemia K562 cells. Cell proliferation was evaluated by the 5-bromo-2-deoxy-uridine (BrdU) incorporation kit. Caspase 3, 8, 9 activities were measured by the caspase assay kit. Protein expression level was detected by western blotting. We found that exposure to propranolol either by combination with carbachol facilitates additive effects on inhibition of caspase 3 and 8 expression in chronic myeloid leukaemia K562 cells. However, caspase 9 expression level was increased by propranolol alone or with propranolol and carbachol combination. The combined therapy of cholinergic and adrenergic receptor drugs will decrease cell proliferation in K562 cells. This decrease in cell proliferation may be mediated by the mitochondrial-dependent intrinsic apoptosis pathway.