Caspase 3-mediated cleavage of p21WAF1/CIP1 associated with the cyclin A-cyclin-dependent kinase 2 complex is a prerequisite for apoptosis in SK-HEP-1 cells.

Abstract

Apoptosis of SK-HEP-1 human hepatoma cells induced by treatment with ginsenoside Rh2 (G-Rh2) is associated with rapid and selective activation of cyclin A-associated cyclin-dependent kinase 2 (Cdk2). Here, we show that in apoptotic cells, the Cdk inhibitory protein p21(WAF1/CIP1), which is associated with the cyclin A-Cdk2 complex, undergoes selective proteolytic cleavage. In contrast, another Cdk inhibitory protein, p27(KIP1), which is associated with cyclin A-Cdk2 and cyclin E-Cdk2 complexes, remained unaltered during apoptosis. Ectopic overexpression of p21(WAF1/CIP1) suppressed apoptosis as well as cyclin A-Cdk2 activity induced by treatment of SK-HEP-1 cells with G-Rh2. The suppressive effects of p21(WAF1/CIP1) were much higher in the cells transfected with p21D112N, an expression vector that encodes a p21(WAF1/CIP1) mutant resistant to caspase 3 cleavage. Overexpression of cyclin A in SK-HEP-1 cells dramatically up-regulated cyclin A-Cdk2 activity and accordingly enhances apoptosis induced by treatment with G-Rh2. These up-regulating effects were blocked by coexpression of a dominant negative allele of cdk2. Furthermore, olomoucine, a specific inhibitor of Cdks, also blocked G-Rh2-induced apoptosis. These data suggest that the induction of apoptosis in human hepatoma cells treated with G-Rh2 occurs by a mechanism that involves the activation of cyclin A-Cdk2 by caspase 3-mediated cleavage of p21(WAF1/CIP1).

• Authors: Y H Jin, K J Yoo, Y H Lee, S K Lee
• Journal: The Journal of biological chemistry (J Biol Chem) Vol. 275 Issue 39 Pg. 30256-63 (Sep 29 2000) ISSN: 0021-9258 [Print] United States
• PMID: 10884382 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

• CDKN1A protein, human
• Cell Cycle Proteins
• Cyclin A
• Cyclin E
• Cyclin-Dependent Kinase Inhibitor p21
• Cyclins
• Ginsenosides
• Microtubule-Associated Proteins
• Purines
• Saponins
• Tumor Suppressor Proteins
• Cyclin-Dependent Kinase Inhibitor p27
• olomoucine
• ginsenoside Rh2
• Protein Serine-Threonine Kinases
• CDC2-CDC28 Kinases
• CDK2 protein, human
• Cyclin-Dependent Kinase 2
• Cyclin-Dependent Kinases
• CASP3 protein, human
• Caspase 3
• Caspases
• Kinetin

Topics

• Apoptosis
• CDC2-CDC28 Kinases
• Caspase 3
• Caspases (metabolism)
• Cell Cycle Proteins
• Cyclin A (metabolism)
• Cyclin E (metabolism)
• Cyclin-Dependent Kinase 2
• Cyclin-Dependent Kinase Inhibitor p21
• Cyclin-Dependent Kinase Inhibitor p27
• Cyclin-Dependent Kinases (antagonists & inhibitors, metabolism)
• Cyclins (genetics, metabolism)
• Endothelium, Vascular (cytology, drug effects)
• Enzyme Activation
• Ginsenosides
• Humans
• Kinetin
• Microtubule-Associated Proteins (metabolism)
• Mutation
• Protein Serine-Threonine Kinases (antagonists & inhibitors, metabolism)
• Purines (pharmacology)
• Saponins (pharmacology)
• Tumor Cells, Cultured
• Tumor Suppressor Proteins