Activation of non neuronal cholinergic system induces proliferation and angiogenesis in MCF-7 human mammary adenocarcinoma cells

GABRIEL L. FISZMAN, MARÍA CRISTINA MIDDONNO, EULALIA DE LA TORRE, MARIANA FARINA, ALEJANDRO J. ESPAÑOL, MARÍA ELENA SALES.

Los Angeles, California, USA.

Congreso; Annual Meeting of the American Association for Cancer Research (AACR).; 2007

Muscarinic acetylcholine receptors (mAChR) are members of the G-protein coupled receptor family (GPCR) that play key physiological roles. Changes in their expression and or function can be involved in several diseases. Distribution and functions of mAChR-G has been extensively reviewed in various human tissues including immunocompetent cells such as lymphocytes, macrophages and mast cells as well as in different epithelial cells and vascular endothelial cells. Five distinct but highly homologous subtypes, M1-M5, were cloned and are encoded by five separate genes. M1, M3 and M5 receptors couple to Gq/G11 and potently stimulate phosphatidylinositol metabolism, arachidonic acid release, tyrosine kinase and calcium influx. The M2 and M4 subtypes preferentially interact with Gi/G0 family and attenuate adenylate cyclase activity, reducing intracellular levels of cAMP. However, it has been demonstrated that most biological responses mediated by GPCRs are not dependent exclusively on the classical pathways mentioned above. The stimulation of mAChR by agonists can promote proliferation and growth of tumor cells by gene expression regulation. Previously, we demonstrated that mAChR expression is up-regulated in three different cell lines derived from distinct murine mammary adenocarcinomas. Furthermore, the activation of these receptors promotes murine breast tumor progression. Less knowledge is available about the response of different mAChR subtypes to muscarinic agonists in human breast cancer cells. In this work we demondtrate that v     MCF-7 cells constitutively express mAChR predominantly M3 and M4 subypes. v      Carbachol stimulates MCF-7 tumor cells proliferation via M3 and M1 receptors activating NOS as its effector enzyme via PLC and PKC signaling pathway. NOS1 and NOS3 isoforms are expressed in MCF-7 cells. v      Carbachol promotes tumor cells induced angiogenesis in vivo. This effect was due on the one hand to NO synthesis by M3 receptor activation and on the other hand to VEGF-A up-regulated expression via M2 receptor subtype