Cell Shape Change Precedes Staurosporine-Induced Stabilization and Accumulation of p27kip1

• Published in: Experimental cell research 2002-11, Vol.280 (2), p.233-243
• Main Authors: Nishi, Kayoko, Schnier, Joachim B., Bradbury, Morton E.
• Format: Article
• Language: English
• Subjects: Cell Cycle - drug effects; Cell Cycle - physiology; Cell Cycle Proteins - genetics; Cell Cycle Proteins - metabolism; Cell Size; Cyclin-Dependent Kinase Inhibitor p27; Cyclin-Dependent Kinases - antagonists & inhibitors; Cycloheximide - pharmacology; Cysteine Endopeptidases - metabolism; Cytochalasin D - pharmacology; Cytoskeleton - drug effects; Cytoskeleton - metabolism; Diacetyl - analogs & derivatives; Diacetyl - pharmacology; Enzyme Inhibitors - pharmacology; Female; Flow Cytometry; Humans; Lung Neoplasms; Microscopy, Confocal; Multienzyme Complexes - antagonists & inhibitors; Multienzyme Complexes - metabolism; Nucleic Acid Synthesis Inhibitors - pharmacology; Proteasome Endopeptidase Complex; Protein Synthesis Inhibitors - pharmacology; Staurosporine - pharmacology; Tumor Cells, Cultured; Tumor Suppressor Proteins - genetics; Tumor Suppressor Proteins - metabolism; Uterine Cervical Neoplasms
• ISSN: 0014-4827; 1090-2422
• DOI: 10.1006/excr.2002.5637

The requirement of an intact cytoskeleton organization for G1/S cell cycle progression has been demonstrated in cultured cells. In the non-small-cell lung carcinoma cell line A549, the kinase inhibitor staurosporine induced G1 cell cycle arrest with an accumulation of the cyclin-dependent kinase inhibitor p27kip1. Staurosporine induced also a drastic change in cell shape that was accompanied by changes in the actin cytoskeleton. The cytoskeleton disruption agents, cytochalasin D (cyto D) and 2,3-butanedione 2-monoxime (BDM), also induced G1 cell cycle arrest in A549 cells but without an accumulation of p27kip1. A comparison of the cell shape changes caused by these agents revealed that a conversion from an epithelial polygonal shape to an elongated fibroblast-like shape was specific for staurosporine. The shape change induced by staurosporine preceded the accumulation of p27kip1 by about 4 h. The accumulation of p27kip1 was not due to enhanced transcription but to stabilization of the protein resulting from the inhibition of proteolytic degradation. Staurosporine, however, did not inhibit directly the proteasome that was involved in the cell-cycle-dependent p27kip1 degradation. The results indicate that the cell shape change caused by staurosporine correlates with the accumulation of p27kip1 and that staurosporine interferes with the p27kip1-specific proteolysis activity.