Assuntos
Amiloidose Familiar/metabolismo , Quimiocina CCL2/metabolismo , Interleucinas/metabolismo , Transdução de Sinais/fisiologia , Dermatopatias Genéticas/metabolismo , Amiloide/metabolismo , Amiloidose Familiar/patologia , Amiloidose Familiar/fisiopatologia , Linhagem Celular , Humanos , Interleucinas/farmacologia , Queratinócitos/efeitos dos fármacos , Queratinócitos/metabolismo , Queratinócitos/patologia , Fator de Transcrição STAT3/metabolismo , Transdução de Sinais/efeitos dos fármacos , Dermatopatias Genéticas/patologia , Dermatopatias Genéticas/fisiopatologiaRESUMO
TGF-beta (transforming growth factor-beta) induces a cytostatic response in most normal cell types. In cancer cells, however, it often promotes metastasis, and its high expression is correlated with poor prognosis. In the present study, we show that S100A4, a metastasis-associated protein, also called metastatin-1, can physically and functionally interact with Smad3, an important mediator of TGF-beta signalling. In agreement with its known property, S100A4 binds to Smad3 in a Ca2+-dependent manner. The S100A4-binding site is located in the N-terminal region of Smad3. S100A4 can potentiate transcriptional activity of Smad3 and the related Smad2. When exogenously expressed in MCF10CA1a.cl1, an MCF10-derived breast cancer cell line, S100A4 increases TGF-beta-induced MMP-9 (matrix metalloproteinase-9) expression. On the other hand, depletion of S100A4 by siRNA (small interfering RNA) from the MDA-MB231 cell line results in attenuation of MMP-9 induction by TGF-beta. Consistent with these observations, S100A4 increases cell invasion ability induced by TGF-beta in MCF10CA1a.cl1 cells, and depletion of the protein in MDA-MB-231 cells inhibits it. Because expression of both S100A4 and TGF-beta is highly elevated in many types of malignant tumours, S100A4 and Smad3 may co-operatively increase metastatic activity of some types of cancer cells.
Assuntos
Movimento Celular/efeitos dos fármacos , Proteínas S100/metabolismo , Proteína Smad3/metabolismo , Fator de Crescimento Transformador beta/farmacologia , Sítios de Ligação , Western Blotting , Cálcio/metabolismo , Linhagem Celular , Linhagem Celular Tumoral , Expressão Gênica/efeitos dos fármacos , Humanos , Imunoprecipitação , Metaloproteinase 9 da Matriz/genética , Metaloproteinase 9 da Matriz/metabolismo , Invasividade Neoplásica , Neoplasias/genética , Neoplasias/metabolismo , Neoplasias/patologia , Ligação Proteica , RNA Interferente Pequeno/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Proteína A4 de Ligação a Cálcio da Família S100 , Proteínas S100/genética , Proteína Smad3/genética , Transfecção , Técnicas do Sistema de Duplo-HíbridoRESUMO
Transforming growth factor-beta (TGF-beta) regulates a wide variety of biological activities. It induces potent growth-inhibitory responses in normal cells but promotes migration and invasion of cancer cells. Smads mediate the TGF-beta responses. TGF-beta binding to the cell surface receptors leads to the phosphorylation of Smad2/3 in their C terminus as well as in the proline-rich linker region. The serine/threonine phosphorylation sites in the linker region are followed by the proline residue. Pin1, a peptidyl-prolyl cis/trans isomerase, recognizes phosphorylated serine/threonine-proline motifs. Here we show that Smad2/3 interacts with Pin1 in a TGF-beta-dependent manner. We further show that the phosphorylated threonine 179-proline motif in the Smad3 linker region is the major binding site for Pin1. Although epidermal growth factor also induces phosphorylation of threonine 179 and other residues in the Smad3 linker region the same as TGF-beta, Pin1 is unable to bind to the epidermal growth factor-stimulated Smad3. Further analysis suggests that phosphorylation of Smad3 in the C terminus is necessary for the interaction with Pin1. Depletion of Pin1 by small hairpin RNA does not significantly affect TGF-beta-induced growth-inhibitory responses and a number of TGF-beta/Smad target genes analyzed. In contrast, knockdown of Pin1 in human PC3 prostate cancer cells strongly inhibited TGF-beta-mediated migration and invasion. Accordingly, TGF-beta induction of N-cadherin, which plays an important role in migration and invasion, is markedly reduced when Pin1 is depleted in PC3 cells. Because Pin1 is overexpressed in many cancers, our findings highlight the importance of Pin1 in TGF-beta-induced migration and invasion of cancer cells.
