title: Nuclear localization of vasoactive intestinal peptide (VIP) receptors in human breast cancer.
abstract: Vasoactive intestinal peptide (VIP) and its receptors (VPACs) are involved in proliferation, survival, and differentiation in human breast cancer cells. Its mechanism of action is traditionally thought to be through specific plasma membrane receptors. There is compelling evidence for a novel intracrine mode of genomic regulation by G-protein-coupled receptors (GPCRs) that implies both endocytosis and nuclear translocation of peripheral GPCR and/or the activation of nuclear-located GPCRs by endogenously-produced, non-secreted ligands. Regarding to VPAC receptors, which are GPCRs, there is only a report suggesting them as a dynamic system for signaling from plasma membrane and nuclear membrane complex. In this study, we show that VPAC(1) receptor is localized in cell nuclear fraction whereas VPAC(2) receptor presents an extranuclear localization and its protein expression is lower than that of VPAC(1) receptor in human breast tissue samples. Both receptors as well as VIP are overexpressed in breast cancer as compared to non-tumor tissue. Moreover, we report the markedly nuclear localization of VPAC(1) receptors in estrogen-dependent (T47D) and independent (MDA-MB-468) human breast cancer cell lines. VPAC(1) receptors are functional in plasma membrane and nucleus as shown by VIP stimulation of cAMP production in both cell lines. In addition, VIP increases its own intracellular and extracellular levels, and could be involved in the regulation of VPAC(1)-receptor traffic from the plasma membrane to the nucleus. These results support new concepts on function and regulation of nuclear GPCRs which could have an impact on development of new therapeutic drugs.
authors.affiliation: Molecular Neuroendocrinology Unit, Department of Biochemistry and Molecular Biology, Alcalá University, 28871 Alcalá de Henares, Spain.
authors.forename: Ana
authors.initials: A
authors.lastname: Valdehita
authors.forename: Ana M
authors.initials: AM
authors.lastname: Bajo
authors.forename: Ana B
authors.initials: AB
authors.lastname: Fernández-Martínez
authors.forename: M Isabel
authors.initials: MI
authors.lastname: Arenas
authors.forename: Eva
authors.initials: E
authors.lastname: Vacas
authors.forename: Pedro
authors.initials: P
authors.lastname: Valenzuela
authors.forename: Antonio
authors.initials: A
authors.lastname: Ruíz-Villaespesa
authors.forename: Juan C
authors.initials: JC
authors.lastname: Prieto
authors.forename: María J
authors.initials: MJ
authors.lastname: Carmena
mesh_terms: D000328:Adult; D000368:Aged; D001940:Breast / Q000378:metabolism*; D001943:Breast Neoplasms / Q000378:metabolism*; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism; D002467:Cell Nucleus / Q000378:metabolism*; D000242:Cyclic AMP / Q000096:biosynthesis; D005260:Female; D006801:Humans; D008875:Middle Aged; D043562:Receptors, G-Protein-Coupled / Q000378:metabolism; D051239:Receptors, Vasoactive Intestinal Peptide, Type II / Q000378:metabolism*; D051238:Receptors, Vasoactive Intestinal Polypeptide, Type I / Q000378:metabolism*; D014660:Vasoactive Intestinal Peptide / Q000378:metabolism / Q000502:physiology
chemical_list: D043562:Receptors, G-Protein-Coupled; D051239:Receptors, Vasoactive Intestinal Peptide, Type II; D051238:Receptors, Vasoactive Intestinal Polypeptide, Type I; D014660:Vasoactive Intestinal Peptide; D000242:Cyclic AMP