| Autor: |
Hu, Xiaotang, Zhang, Xiaohong, Zhong, Qing, Fisher, Ariana B, Bryington, Matthew, Zuckerman, Kenneth S |
| Předmět: |
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| Zdroj: |
Oncogene; 10/18/2001, Vol. 20 Issue 47, p6840, 11p |
| Abstrakt: |
In this report we have studied the mechanism by which Transforming Growth Factor beta (TGFβ) inhibits growth of human myeloid leukemia cell lines. TGFβ1 arrested cells in G1 phase and significantly downregulated the expression of cyclin D2, cyclin D3, cdk4, cyclin A, and cdk2. The downregulation of the molecules resulted in approximately 50–90% decrease of the molecule-dependent kinase activity, varying with each molecule. Although treatment of cells with TGFβ1 up-regulated accumulation of p27kip1 in both nucleus and cytoplasm, the association of the p27kip1 with cdk2, cyclin A, cyclin D2, cyclin D3, and cdk4 was markedly down-regulated, suggesting that p27kip1 is not responsible for the downregulation of the kinase activity. In contrast, TGFβ1 upregulated cyclin E-associated p27kip1 with no effect on the expression of cyclin E. p27kip1-immunodepletion upregulated cyclin E-dependent kinase activity by more than 10-fold in TGFβ1-treated cells but not in proliferating cells; whereas immunodepletion of p27kip1 from cdk2-immunoprecipitates markedly downregulated cdk2 kinase activity in the lysates extracted from both proliferating and TGFβ-treated cells. Consistent with this observation, TGFβ1 and p27kip1 antisense cDNA had a synergistic or additive inhibitory effect on cdk2 but not cyclin E-dependent kinase activity. Our data suggest that (1) TGFβ1-mediated growth inhibition is accomplished through multiple pathways and (2) p27kip1 has opposing effects on cdk2 and cyclin E activity in response to TGFβ1. Oncogene (2001) 20, 6840–6850. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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