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1.
Int J Oncol ; 32(2): 323-31, 2008 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-18202754

RESUMO

Despite advances in biological and molecular characteristics, the prognosis of oral squamous cell carcinomas is still very unfavourable and is based on the classical clinicopathological parameters. However, tumors with similar clinicopathological characteristics may differ dramatically in their clinical outcome. Thus, the identification of novel prognostic factors is necessary to improve prognostic and therapeutic approaches. Transforming growth factor-beta1 (TGF-beta1) is a potent growth inhibitor of epithelial cell proliferation, thus, inactivation of TGF-beta1 signalling may play a role in cancer. The expression levels of TGF-beta1 and its type I and type II receptors (TbetaRI and TbetaRII) were assessed by immunohistochemical and Western blot analyses in 22 oral squamous cell carcinoma lesions, in their normal adjacent mucosa and in the squamous carcinoma cell lines FaDu and CAL27. Immunohistochemistry on 22 oral carcinomas and case-matched normal oral mucosae demonstrated that TGF-beta1, TbetaRI, and TbetaRII were intensively and homogeneously expressed in all normal epithelia. In contrast, TGF-beta1 and its receptors were significantly reduced in poorly (G3) differentiated tumors as compared to moderately (G2) and well differentiated (G1) lesions (p=2.8 x 10(-3), p=1.3 x 10(-3), p=2.8 x 10(-3) and p=1.3 x 10(-3), respectively). The progressive reduction of the expression levels was confirmed by Western blotting. The oral squamous carcinoma cell lines Cal27 and FaDu demonstrated a reduced and a lack of TbetaRI expression, respectively. A significant decrease of TbetaRII expression, as compared to Cal27 cells, was shown in FaDu cells. Thus, the decreased expression of TbetaRII combined with the absence of TbetaRI could account for the resistance of FaDu cells to the growth-inhibiting effect of TGF-beta1. TGF-beta1 and TGF-beta1 receptor expression significantly decreased as tumors became less differentiated and thus more aggressive, suggesting a functional role of these molecules in oral tumor progression.


Assuntos
Carcinoma de Células Escamosas/metabolismo , Regulação Neoplásica da Expressão Gênica , Neoplasias Bucais/metabolismo , Proteínas Serina-Treonina Quinases/biossíntese , Receptores de Fatores de Crescimento Transformadores beta/biossíntese , Fator de Crescimento Transformador beta1/biossíntese , Adulto , Idoso , Idoso de 80 Anos ou mais , Diferenciação Celular , Linhagem Celular Tumoral , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Receptor do Fator de Crescimento Transformador beta Tipo I , Receptor do Fator de Crescimento Transformador beta Tipo II
2.
Arterioscler Thromb Vasc Biol ; 25(11): 2392-7, 2005 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-16151016

RESUMO

OBJECTIVE: Insulin activates several processes potentially dangerous for the arterial wall and hyperinsulinemia might be atherogenic. However, other insulin effects are protective for the vessel wall and thus anti-atherogenic. Aim of this study was to investigate whether insulin effects on potentially pro-atherogenic and anti-atherogenic processes were differently affected in cells from insulin-resistant individuals. METHODS AND RESULTS: We determined insulin effect on nitric oxide (NO) production and plasminogen activator inhibitor (PAI)-1 synthesis in 12 fibroblast strains obtained from skin biopsy samples of 6 insulin-sensitive (IS) (clamp M >7 mg/kg body weight per minute) and 6 insulin-resistant (IR) (clamp M <5 mg/kg body weight per minute) healthy volunteers. Insulin effects on NO release and Akt phosphorylation were significantly impaired in fibroblasts from IR as compared with IS individuals. Conversely, there was not any difference between IR and IS strains in insulin ability to increase PAI-1 antigen levels and, after 24-hour insulin incubation, PAI-1 mRNA increase in IR strains was only slightly less than in IS strains. Insulin ability to induce MAPK activation was also comparable in IR and IS cells. CONCLUSIONS: We conclude that in cells from IR individuals, insulin action on anti-atherogenic processes, such as NO release, is impaired, whereas the hormone ability to stimulate atherogenic processes, such as PAI-1 release, is preserved.


Assuntos
Aterosclerose/metabolismo , Hiperinsulinismo/metabolismo , Resistência à Insulina , Óxido Nítrico/metabolismo , Inibidor 1 de Ativador de Plasminogênio/genética , Adulto , Células Cultivadas , Meios de Cultura , Feminino , Fibroblastos/citologia , Fibroblastos/metabolismo , Glucose/farmacocinética , Glicogênio/biossíntese , Humanos , Insulina/farmacologia , Sistema de Sinalização das MAP Quinases/fisiologia , Masculino , Óxido Nítrico Sintase Tipo III/metabolismo , Fosforilação , Inibidor 1 de Ativador de Plasminogênio/metabolismo , Proteínas Proto-Oncogênicas c-akt/metabolismo , RNA Mensageiro/metabolismo , Serina/metabolismo
3.
Biochem Biophys Res Commun ; 314(3): 704-10, 2004 Feb 13.
Artigo em Inglês | MEDLINE | ID: mdl-14741692

RESUMO

Statins have been shown to interact with several monocyte/macrophage functions. We tested the effect of pravastatin on transforming growth factor-beta1 (TGF-beta1) production and its possible involvement in scavenger receptors class A (SRA) expression in human THP-1 cells. TGF-beta1s biological activity in THP-1 cell conditioned medium, evaluated by luciferase activity of transfected cell with a TGF-beta responsive promoter, was increased in a dose-dependent manner after incubation with pravastatin (1-20 microM). Pravastatin (1-20 microM) induced a dose-dependent increase in TGF-beta1 mRNA expression and protein production in THP-1 cells. PMA-induced SRA gene and protein expression was suppressed by pravastatin with a mean 3-fold decrease at 10 microM. This last effect was reversed by a mouse monoclonal anti-TGF-beta1 neutralizing antibody. PD98059, a specific inhibitor of MAP kinase cascade, completely reversed pravastatin-induced SRA down-regulation. p44 and p42 isoforms showed a dose-dependent phosphorylation after treatment with pravastatin (1-20 microM) which was inhibited by a mouse monoclonal anti-TGF-beta1 antibody. Our results demonstrate that pravastatin significantly up-regulates TGF-beta1 expression which may be in involved in down-regulation of SRA expression in THP-1 cell cultures. A new pathway for pravastatin effects in atherogenesis can be suggested.


Assuntos
Macrófagos/metabolismo , Proteínas de Membrana , Pravastatina/farmacologia , Receptores Imunológicos/biossíntese , Receptores de Lipoproteínas , Fator de Crescimento Transformador beta/biossíntese , Anticorpos/farmacologia , Northern Blotting , Western Blotting , Linhagem Celular , Relação Dose-Resposta a Droga , Inibidores Enzimáticos/farmacologia , Humanos , Macrófagos/efeitos dos fármacos , Proteínas Quinases Ativadas por Mitógeno/antagonistas & inibidores , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Fosforilação , RNA Mensageiro/biossíntese , RNA Mensageiro/genética , Receptores Depuradores , Receptores Depuradores Classe A , Receptores Depuradores Classe B , Fator de Crescimento Transformador beta/genética , Fator de Crescimento Transformador beta/imunologia , Fator de Crescimento Transformador beta1 , Regulação para Cima/efeitos dos fármacos
4.
Exp Cell Res ; 287(2): 411-23, 2003 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-12837295

RESUMO

Transforming growth factor beta 1 (TGF-beta 1) and insulin-like growth factor I (IGF-I) have contrasting effects on cell cycle regulation in thyroid cells and TGF-beta 1 induces a dramatic decrease in IGF-I-induced cell proliferation. The aim of the present study was to investigate the molecular mechanism of cross-talk between TGF-beta 1 and IGF-I in FRTL-5 cells. TGF-beta 1 affected IGF-I-stimulated insulin receptor substrate 1 (IRS-1) tyrosine phosphorylation and its association with Grb2 protein. Moreover, TGF-beta 1 decreased the IGF-I-induced tyrosine phosphorylation of the adaptor protein CrkII and its association with the IGF-I receptor. These results were accompanied by TGF-beta 1 inhibition of IGF-I-stimulated mitogen-activated protein kinase phosphorylation and activation. Conversely, TGF-beta 1 did not alter IGF-I-stimulated IRS-1-associated phosphatidylinositol 3-kinase activity, IGF-I-induced tyrosine phosphorylation of Shc, and its binding to Grb2. Taken together, these findings provide a molecular basis for the growth-inhibitory action of TGF-beta 1 on the IGF-I-induced mitogenic effect.


Assuntos
Células Epiteliais/metabolismo , Fator de Crescimento Insulin-Like I/metabolismo , Transdução de Sinais , Fator de Crescimento Transformador beta/farmacologia , Animais , Divisão Celular/efeitos dos fármacos , Linhagem Celular , Ativação Enzimática , Células Epiteliais/efeitos dos fármacos , Proteínas Quinases Ativadas por Mitógeno/efeitos dos fármacos , Proteínas Quinases Ativadas por Mitógeno/metabolismo , Fosforilação , Proteínas Proto-Oncogênicas/efeitos dos fármacos , Proteínas Proto-Oncogênicas/metabolismo , Proteínas Proto-Oncogênicas c-crk , Ratos , Receptor de Insulina/metabolismo , Glândula Tireoide , Tirosina/metabolismo
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