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.

NEGRONI MARIA PIA; FISZMAN GABRIEL L; AZAR ME; MORGADO CC; ESPAÑOL ALEJANDRO JAVIER; PELEGRINA LAURA TATIANA; DE LA TORRE EULALIA; SALES MARÍA ELENA

JOURNAL OF CLINICAL IMMUNOLOGY

Springer

Lugar: Netherlands; Año: 2010 p. 474 - 484

0271-9142

NTRODUCTION: 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. DISCUSSION: 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.