Expression of G1 phase regulators in MG-63 osteosarcoma cell line

Mara Merli, Maria Serena Benassi, Gabriella Gamberi, Paola Ragazzini, Maria Rosa Sollazzo, Lara Molendini, Giovanna Magagnoli, Cristina Ferrari, Maria Cristina Maltarello, Piero Picci

Research output: Contribution to journalArticlepeer-review


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-α (TNF-α) and interleukin-6 (IL-6). Cell proliferation analysis demonstrated an increased proliferation of MG-63 cells with IL-6, while TNF-α acted as an antiproliferative agent. Immunoblotting revealed an increased expression of p21 with TNF-α and its complex with cdk2. TNF-α reduced the expression of the cyclin E-cdk2 complex. TNF-α 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-α 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.

Original languageEnglish
Pages (from-to)1117-1121
Number of pages5
JournalInternational Journal of Oncology
Issue number6
Publication statusPublished - Jun 1999


  • Cell cycle
  • Cell cycle inhibitors
  • Cyclin-dependent kinases
  • Cyclins
  • Cytokines

ASJC Scopus subject areas

  • Cancer Research
  • Oncology


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