Activation of MAP kinase by muscarinic cholinergic receptors induces cell proliferation and protein synthesis in human breast cancer cells.
Carbachol (Cch), a muscarinic acetylcholine receptor (mAChR) agonist, increases intracellular-free Ca(2+) mobilization and induces mitogen-activated protein kinase/extracellular signal-regulated kinase (MAPK/ERK) phosphorylation in MCF-7 human breast cancer cells. Pretreatment of cells with the selective phospholipase C (PLC) inhibitor U73122, or incubation of cells in a Ca(2+)-free medium did not alter Cch-stimulated MAPK/ERK phosphorylation. Phosphorylation of MAPK/ERK was mimicked by phorbol 12-myristate acetate (PMA), an activator of protein kinase C (PKC), but Cch-evoked MAPK/ERK activation was unaffected by down-regulation of PKC or by pretreatment of cells with GF109203X, a PKC inhibitor. However, Cch-stimulated MAPK/ERK phosphorylation was completely blocked by myristoylated PKC-zeta pseudosubstrate, a specific inhibitor of PKC-zeta, and high doses of staurosporine. Pretreatment of human breast cancer cells with wortmannin or LY294002, selective inhibitors of phosphoinositide 3-kinase (PI3K), diminished Cch-mediated MAPK/ERK phosphorylation. Similar results were observed when MCF-7 cells were pretreated with genistein, a non-selective inhibitor of tyrosine kinases, or with the specific Src tyrosine kinase inhibitor PP2. Moreover, in MCF-7 human breast cancer cells mAChR stimulation induced an increase of protein synthesis and cell proliferation, and these effects were prevented by PD098059, a specific inhibitor of the mitogen activated kinase kinase. In conclusion, analyses of mAChR downstream effectors reveal that PKC-zeta, PI3K, and Src family of tyrosine kinases, but not intracellular-free Ca(2+) mobilization or conventional and novel PKC activation, are key molecules in the signal cascade leading to MAPK/ERK activation. In addition, MAPK/ERK are involved in the regulation of growth and proliferation of MCF-7 human breast cancer cells.
Jiménez
Eugenio
E
Department of Biochemistry and Molecular Biology, Malaga University, Malaga, Spain. ejg@uma.es
Montiel
Mercedes
M
D001692:Biological Transport; D001943:Breast Neoplasms / Q000378:metabolism* / Q000473:pathology*; D002118:Calcium / Q000378:metabolism; D002217:Carbachol / Q000494:pharmacology; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D018679:Cholinergic Agonists / Q000494:pharmacology; D004789:Enzyme Activation; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism; D005260:Female; D006801:Humans; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009363:Neoplasm Proteins / Q000096:biosynthesis*; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D011493:Protein Kinase C / Q000378:metabolism; D011505:Protein-Tyrosine Kinases / Q000378:metabolism; D011976:Receptors, Muscarinic / Q000378:metabolism*
D018679:Cholinergic Agonists; D009363:Neoplasm Proteins; D011976:Receptors, Muscarinic; D002217:Carbachol; D019869:Phosphatidylinositol 3-Kinases; D011505:Protein-Tyrosine Kinases; D011493:Protein Kinase C; D048049:Extracellular Signal-Regulated MAP Kinases; D020928:Mitogen-Activated Protein Kinases; D002118:Calcium