RESUMO
p75NTR is a member of the tumor necrosis superfamily of proteins which is variably associated with induction of apoptosis and proliferation. Cyclin D2 is one of the mediators of cellular progression through G1 phase of the cell cycle. The present study demonstrates the inverse relationship between expression of cyclin D2 and expression of p75NTR in PC12 cells. Induction of p75NTR expression in p75NTR-negative PC12 cells results in downregulation of cyclin D2; suppression of p75NTR expression with siRNA in native PC12 cells results in upregulation of cyclin D2. The effects of p75NTR on cyclin D2 expression are mimicked in p75NTR-negative cells by transfection with the intracellular domain of p75NTR. Cyclin-D2-positive PC12 cell cultures grow more slowly than cyclin-D2-negative cultures, and induction of expression of cyclin D2 slows the culture growth rate of cyclin-D2-negative cells. Finally, subcutaneous murine xenografts of cyclin-D2-negative, p75NTR-positive PC12 cells more frequently and more rapidly produce tumors than the analogous xenografts of cyclin-D2-positive, p75NTR-negative cells. These results suggest that p75NTR suppresses cyclin D2 expression in PC12 cells by a mechanism distinct from its function as a nerve growth factor receptor and that cyclin D2 expression decreases cell culture and xenografted tumor growth.
Assuntos
Ciclinas/metabolismo , Regulação para Baixo , Neoplasias Experimentais/patologia , Receptor de Fator de Crescimento Neural/metabolismo , Animais , Ciclina D2 , Masculino , Camundongos , Transplante de Neoplasias , Neoplasias Experimentais/metabolismo , Células PC12 , Estrutura Terciária de Proteína , RNA Interferente Pequeno/genética , Ratos , Receptor de Fator de Crescimento Neural/química , Receptor de Fator de Crescimento Neural/genética , Transfecção , Transplante HeterólogoRESUMO
Interferon alfa-2a is a cytokine produced by recombinant DNA techniques and has antiproliferative, antiviral and immunomodulating effects. A number of case reports in the past have suggested relative safety of alpha-interferons during pregnancy with little or no effect on the fetus. A 15-year-old adolescent became pregnant while receiving alpha-interferon for essential thrombocythemia. She delivered a small-for-gestational age baby girl at 33 weeks gestation. The infant displayed a facial rash characteristic of neonatal lupus and transient thrombocytopenia; maternal and neonatal serologies were typical for drug-induced lupus. These findings suggest probable association between maternal use of alpha interferon and adverse effects in the fetus.
