Immunoglobulin G from breast cancer patients in stage I stimulates muscarinic acetylcholine receptors in MCF7 cells and induces proliferation. Participation of nitric oxide synthase-derived nitric oxide.
BACKGROUND
Muscarinic acetylcholine receptors (mAChR) belong to the G-protein-coupled receptor family and are extensively expressed in most cells in mammals. We had reported the expression of mAChR in murine and human breast tumors.


METHODS
The presence of antibodies in the sera of patients with different tumors directed against self-proteins has been recently described. In this work, we investigated the presence of autoantibodies against mAChR in the sera of breast cancer patients in stage I (T1N0Mx-IgG). IgG purification was performed by affinity chromatography in protein G-agarose. We also studied the ability of these antibodies to modulate the proliferation of MCF-7 breast tumor cells by the MTS colorimetric assay. The ability of T1N0Mx-IgG to stimulate muscarinic signaling pathway via nitric oxide synthase was tested by Griess reaction.


RESULTS
We demonstrated M(3) and M(4) receptors expression in MCF-7 cells. T1N0Mx-IgG promotes cell proliferation, mimicking the action of the muscarinic agonist carbachol. This effect was preferentially due to M(3) receptor activation in tumor cells via phospholipase C-induced nitric oxide liberation by calcium-dependent nitric oxide synthases. IgG from control patients was unable to produce this effect.


CONCLUSIONS
IgG from patients with breast cancer in early stages could be promoting tumor progression by muscarinic activation, and its presence could be determining the prognosis of this illness.
Centro de Estudios Farmacológicos y Botánicos (CEFYBO)-Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) Facultad de Medicina, Universidad de Buenos Aires, Paraguay 2155 piso 16, CP 1121 Ciudad Autónoma de Buenos Aires, Argentina.
María Pía
MP
Negroni
Gabriel L
GL
Fiszman
María E
ME
Azar
Carlos Cresta
CC
Morgado
Alejandro J
AJ
Español
Laura T
LT
Pelegrina
Eulalia
E
de la Torre
María Elena
ME
Sales
D001323:Autoantibodies / Q000302:isolation & purification / Q000494:pharmacology*; D001943:Breast Neoplasms / Q000188:drug therapy / Q000276:immunology* / Q000473:pathology / Q000503:physiopathology; D002217:Carbachol / Q000494:pharmacology; D002277:Carcinoma / Q000188:drug therapy / Q000276:immunology* / Q000473:pathology / Q000503:physiopathology; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D018679:Cholinergic Agonists / Q000494:pharmacology; D002846:Chromatography, Affinity; D018450:Disease Progression; D005260:Female; D006801:Humans; D007074:Immunoglobulin G / Q000302:isolation & purification / Q000494:pharmacology*; D009367:Neoplasm Staging; D009569:Nitric Oxide / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000378:metabolism; D043587:Receptor, Muscarinic M3 / Q000276:immunology; D043588:Receptor, Muscarinic M4 / Q000276:immunology; D015398:Signal Transduction / Q000187:drug effects
D001323:Autoantibodies; D018679:Cholinergic Agonists; D007074:Immunoglobulin G; D043587:Receptor, Muscarinic M3; D043588:Receptor, Muscarinic M4; D009569:Nitric Oxide; D002217:Carbachol; D019001:Nitric Oxide Synthase