Cyclin-dependent kinase 4-mediated phosphorylation inhibits Smad3 activity in cyclin D-overexpressing breast cancer cells
| Autor: | Jacqueline S. Jeruss, Ron Kall, Anne E. Cooley, Stanislav Zelivianski |
|---|---|
| Rok vydání: | 2010 |
| Předmět: |
Cancer Research
Cyclin D Cyclin B Breast Neoplasms Gene Expression Regulation Enzymologic Article Cyclin D1 Cyclin-dependent kinase Cell Line Tumor Humans Smad3 Protein Phosphorylation Molecular Biology Cyclin integumentary system biology Cyclin-dependent kinase 4 Kinase Cell Cycle Cyclin-Dependent Kinase 4 Molecular biology Enzyme Activation Gene Expression Regulation Neoplastic Oncology biology.protein Cancer research Female biological phenomena cell phenomena and immunity Cyclin A2 |
| Zdroj: | Molecular cancer research : MCR. 8(10) |
| ISSN: | 1557-3125 |
| Popis: | Smad3, a component of the transforming growth factor β signaling cascade, contributes to G1 arrest in breast cancer cells. Cyclin D1/cyclin-dependent kinase 4 (CDK4) promotes G1-S–phase transition, and CDK phosphorylation of Smad3 has been associated with inhibition of Smad3 activity. We hypothesized that overexpression of cyclin D1 exerts tumorigenic effects in breast cancer cells through CDK4-mediated phosphorylation and inhibition of Smad3 and release of G1 arrest. Real-time quantitative reverse transcription-PCR and immunoblotting were used to evaluate expression of study proteins in cyclin D1–overexpressing breast cancer cells. Smad3 transcriptional activity and cell cycle control were examined in cells transfected with wild-type (WT) Smad3 or Smad3 with single or multiple CDK phosphorylation site mutations (M) in the presence or absence of the CDK4 inhibitor or cotransfection with cdk4 small interfering RNA (siRNA). Transfection of the Smad3 5M construct resulted in decreased c-myc and higher p15INK4B expression. Compared with WT Smad3, overexpression of the Smad3 T8, T178, 4M, or 5M mutant constructs resulted in higher Smad3 transcriptional activity. Compared with cells transfected with WT Smad3, Smad3 transcriptional activity was higher in cells overexpressing Smad3 mutant constructs and treated with the CDK4 inhibitor or transfected with cdk4 siRNA. Cells transfected with Smad3 T8 or T178 and treated with the CDK4 inhibitor showed an increase in the G1 cell population. Inhibition of CDK-mediated Smad3 phosphorylation released cyclin D1–regulated blockade of Smad3 transcriptional activity and recovered cell cycle arrest in breast cancer cells. Targeted inhibition of CDK4 activity may have a role in the treatment of cyclin D–overexpressing breast cancers. Mol Cancer Res; 8(10); 1375–87. ©2010 AACR. |
| Databáze: | OpenAIRE |
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