Both low and high concentrations of staurosporine induce G1 arrest through down-regulation of cyclin E and cdk2 expression.
Staurosporine has been reported to cause arrest of cells in G1 phase at low concentration and in G2 phase at high concentration. This raises the question of why the effects of staurosporine on the cell cycle depend on the applied concentration. In order to verify these multiple functions of staurosporine in Meth-A cells, we used cyclin E as a landmark of G1/S transition, cyclin B as a landmark of G2/M transition and MPM2 as a hallmark of M phase. We found that staurosporine arrested cells in G1 phase at a low concentration (20 nM) and in G2/M phase at a high concentration (200 nM). However, 200 nM staurosporine increased the expression of cyclin B and cdc2 proteins, suggesting that the cells progressed through the G2/M transition, and increased the expression of MPM2 protein, indicating that the cells entered M phase. Moreover, 200 nM staurosporine increased the expression of p53 and p21 proteins and inhibited the expression of cyclin E and cdk2 proteins, suggesting that the cells were arrested in the G1 phase of the next cycle. Morphological observation showed similar results as well. These data suggest that the G2/M accumulation induced by 200 nM staurosporine does not reflect G2 arrest, but rather results from M phase arrest, followed by progression from M phase to the G1 phase of the next cycle without cytokinesis, and finally arrest of the cells in G1 phase.
Zong
Z P
ZP
Division of Basic Science, Medical Research Institute, Kanazawa Medical University, Ishikawa, Japan. zong3961@kanazawa-med.ac.jp
Fujikawa-Yamamoto
K
K
Li
A L
AL
Yamaguchi
N
N
Chang
Y G
YG
Murakami
M
M
Odashima
S
S
Ishikawa
Y
Y
D000818:Animals; D042846:CDC2-CDC28 Kinases; D002453:Cell Cycle / Q000187:drug effects / Q000502:physiology; D002455:Cell Division / Q000187:drug effects / Q000502:physiology; D048429:Cell Size; D019926:Cyclin B / Q000032:analysis / Q000187:drug effects / Q000378:metabolism; D019927:Cyclin E / Q000187:drug effects* / Q000378:metabolism*; D051357:Cyclin-Dependent Kinase 2; D018844:Cyclin-Dependent Kinases / Q000187:drug effects* / Q000378:metabolism*; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D000072278:Forkhead Box Protein M1; D051858:Forkhead Transcription Factors; D016193:G1 Phase / Q000187:drug effects* / Q000502:physiology*; D016195:G2 Phase / Q000187:drug effects / Q000502:physiology; D051379:Mice; D008938:Mitosis / Q000187:drug effects / Q000502:physiology; D010750:Phosphoproteins / Q000032:analysis / Q000187:drug effects / Q000378:metabolism; D017346:Protein Serine-Threonine Kinases / Q000187:drug effects* / Q000378:metabolism*; D019311:Staurosporine / Q000494:pharmacology*; D013997:Time Factors; D014157:Transcription Factors; D014407:Tumor Cells, Cultured
D019926:Cyclin B; D019927:Cyclin E; D004791:Enzyme Inhibitors; D000072278:Forkhead Box Protein M1; D051858:Forkhead Transcription Factors; C491524:Foxm1 protein, mouse; D010750:Phosphoproteins; D014157:Transcription Factors; D017346:Protein Serine-Threonine Kinases; D042846:CDC2-CDC28 Kinases; C495893:Cdk2 protein, mouse; D051357:Cyclin-Dependent Kinase 2; D018844:Cyclin-Dependent Kinases; D019311:Staurosporine