Related Experiment Videos
Inhibition of cdk2 activating phosphorylation by mevastatin
Chinweike Ukomadu1, Anindya Dutta
1Department of Pathology, Brigham and Women's Hospital, Harvard Medical School, Boston, Massachusetts 02115, USA.
Abstract:
Phosphorylation of cdk2 on threonine 160 is essential for kinase activity. Mevastatin, an inhibitor of cholesterol synthesis, inhibits cell growth through inhibition of cdk2 and this has been suggested to be due to enhancement of p21 levels. In a prostate cancer cell line, PC3, mevastatin treatment led to elevated levels of p21 and caused a small increase in the p21 associated with cdk2. However, this increase in the associated p21 appeared out of proportion with the resulting dramatic inhibition of kinase activity. Using RNA interference we show that mevastatin inhibits cdk2 activity despite lack of induction of p21, p27, and p57. Instead the kinase was inhibited due to a decrease in activating phosphorylation. Phosphorylation of cdk2 from mevastatin-treated cells with exogenous cyclin-dependent kinase (cdk)-activating enzymes restored its functional activity. The only known mammalian cyclin H.cdk7.mat1 complex (cdk2-activating kinase, Cak), was not inhibited by mevastatin, suggesting either that a different CAK is responsible for cdk2 phosphorylation in vivo or that the regulation is at the level of substrate accessibility or of cdk2 dephosphorylation. These results suggest that mevastatin inhibits cdk2 activity in PC3 cells through the inhibition of Thr-160 phosphorylation of cdk2, providing a novel example of regulation of cdk2 at this level.
Insights
Mevastatin inhibits prostate cancer cell growth by decreasing cyclin-dependent kinase 2 (cdk2) phosphorylation, not by increasing p21 levels. This novel regulation of cdk2 activity offers new therapeutic insights.
Area of Science:
- Cell Biology
- Molecular Pharmacology
- Cancer Research
Background:
- Cyclin-dependent kinase 2 (cdk2) phosphorylation at threonine 160 is crucial for its kinase activity.
- Mevastatin, a cholesterol synthesis inhibitor, has been proposed to inhibit cell growth by increasing p21 levels, thereby inhibiting cdk2.
Purpose of the Study:
- To investigate the mechanism by which mevastatin inhibits cdk2 activity in PC3 prostate cancer cells.
- To determine if p21 induction is the primary mechanism of cdk2 inhibition by mevastatin.
Main Methods:
- Utilized RNA interference to assess mevastatin's effect on cdk2 activity and related proteins (p21, p27, p57).
- Examined the role of activating phosphorylation in mevastatin-induced cdk2 inhibition.
- Tested the effect of exogenous cyclin-dependent kinase (cdk)-activating enzymes on mevastatin-treated cells.
Main Results:
- Mevastatin inhibited cdk2 activity in PC3 cells independently of p21, p27, or p57 induction.
- The inhibition was associated with decreased activating phosphorylation of cdk2 at threonine 160.
- Restoration of cdk2 activity was achieved by adding exogenous cdk-activating enzymes.
- The known cdk-activating kinase (CAK) complex was not inhibited by mevastatin.
Conclusions:
- Mevastatin inhibits cdk2 activity in PC3 cells by reducing Thr-160 phosphorylation.
- This represents a novel mechanism of cdk2 regulation.
- Further research is needed to identify the specific CAK or regulatory mechanism involved.