Expression of G1 phase regulators in MG-63 osteosarcoma cell line.
Int J Oncol
; 14(6): 1117-21, 1999 Jun.
Article
em En
| MEDLINE
| ID: mdl-10339667
ABSTRACT
Cyclins and cyclin-dependent kinases (cdks) form complexes that govern transitions during cell cycle phases. In this study we characterized a human osteosarcoma cell line, MG-63, for the expression level of cyclin D1, cyclin E, cdk4, cdk2, and cell cycle inhibitors pRb and p21. To investigate the role of these proteins we treated MG-63 cells with tumor necrosis factor-alpha (TNF-alpha) and interleukin-6 (IL-6). Cell proliferation analysis demonstrated an increased proliferation of MG-63 cells with IL-6, while TNF-alpha acted as an anti-proliferative agent. Immunoblotting revealed an increased expression of p21 with TNF-alpha and its complex with cdk2. TNF-alpha reduced the expression of the cyclin E-cdk2 complex. TNF-alpha did not affect the amount of cyclin D1, cyclin E, cdk4, cdk2, and of cyclin D1-cdk4 complex. IL-6 decreased p21 expression and its complex with cdk2, while it increased the cyclin E-cdk2 complex. Cyclin D1 and cdk4 expression and their complex did not change after IL-6 treatment, nor did cyclin E and cdk2 protein expression. Hyperphosphorylated/dephosphorylated Rb protein ratio was reduced with TNF-alpha whereas it increased with IL-6. These results may suggest an important role of p21 and of cyclin E-cdk2 complex in the G1 phase regulation through pRb phosphorylation in MG-63 cells.
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Base de dados:
MEDLINE
Assunto principal:
Neoplasias Ósseas
/
Osteossarcoma
/
Fase G1
/
Proteínas Proto-Oncogênicas
/
Proteínas de Ciclo Celular
/
Quinases relacionadas a CDC2 e CDC28
Idioma:
En
Ano de publicação:
1999
Tipo de documento:
Article