title: Inhibition of serum-stimulated mitogen activated protein kinase by 1alpha,25(OH)2-vitamin D3 in MCF-7 breast cancer cells.
abstract: 1alpha,25-Dihydroxyvitamin D3 [1alpha,25(OH)2D3], the hormonally active form of vitamin D3, has been shown to be a potent negative growth regulator of breast cancer cells both in vitro and in vivo. 1alpha,25(OH)2D3 acts through two different mechanisms. In addition to regulating gene transcription via its specific intracellular receptor (vitamin D receptor, VDR), 1alpha,25(OH)2D3 induces rapid, non-transcriptional responses involving activation of transmembrane signal transduction pathways, like growth factors and peptide hormones. The mechanisms that mediate the antiproliferative effects of 1alpha,25(OH)2D3 in breast cancer cells are not fully understood. Particularly, there is no information about the early non-genomic signal transduction effectors modulated by the hormone. The present study shows that 1alpha,25(OH)2D3 rapidly inhibits serum induced activation of ERK-1 and ERK-2 MAP kinases. The tyrosine kinase Src is involved in the pathway leading to activation of ERK 1/2 by serum. Furthermore, 1alpha,25(OH)2D3 increases the tyrosine-phosphorylated state of Src and inhibits its kinase activity, while induces the association of the VDR with Src, either in the presence or absence of serum. In parallel, the hormone rapidly increases the amounts of VDR associated to plasma membranes (PM). Pretreatment with the tyrosine phosphatase inhibitors orthovanadate or bpV (phen) prevented mitogen-activated protein kinase (MAPK) inhibition by 1alpha,25(OH)2D3. These data altogether suggest that 1alpha,25(OH)2D3 inhibits the MAPK cascade by inactivating Src tyrosine kinase through a mechanism mediated by the VDR and tyrosine phosphatases.
authors.affiliation: Instituto de Ingeniería Genética y Biología Molecular, Vuelta de Obligado 2490, 1428 Buenos Aires, Argentina.
authors.forename: Daniela A
authors.initials: DA
authors.lastname: Capiati
authors.forename: Ana M
authors.initials: AM
authors.lastname: Rossi
authors.forename: Gabriela
authors.initials: G
authors.lastname: Picotto
authors.forename: Silvia
authors.initials: S
authors.lastname: Benassati
authors.forename: Ricardo L
authors.initials: RL
authors.lastname: Boland
mesh_terms: D001943:Breast Neoplasms / Q000201:enzymology*; D002117:Calcitriol / Q000494:pharmacology*; D045744:Cell Line, Tumor; D002462:Cell Membrane / Q000378:metabolism; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D049109:Cell Proliferation / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D020928:Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D019000:Phosphotyrosine / Q000378:metabolism; D011485:Protein Binding / Q000187:drug effects; D021381:Protein Transport / Q000187:drug effects; D017027:Protein Tyrosine Phosphatases / Q000037:antagonists & inhibitors / Q000378:metabolism; D016392:Proto-Oncogene Proteins pp60(c-src) / Q000037:antagonists & inhibitors / Q000378:metabolism; D011720:Pyrazoles / Q000494:pharmacology; D011743:Pyrimidines / Q000494:pharmacology; D018167:Receptors, Calcitriol / Q000378:metabolism; D044967:Serum; D015398:Signal Transduction / Q000187:drug effects
chemical_list: C108123:4-amino-5-(4-methylphenyl)-7-(tert-butyl)pyrazolo(3,4-d)pyrimidine; D004791:Enzyme Inhibitors; D011720:Pyrazoles; D011743:Pyrimidines; D018167:Receptors, Calcitriol; D019000:Phosphotyrosine; D016392:Proto-Oncogene Proteins pp60(c-src); D020928:Mitogen-Activated Protein Kinases; D017027:Protein Tyrosine Phosphatases; D002117:Calcitriol