Induction of apoptosis by staurosporine involves the inhibition of expression of the major cell cycle proteins at the G(2)/m checkpoint accompanied by alterations in Erk and Akt kinase activities.
BACKGROUND
Staurosporine is a therapeutic agent that inhibits tumor cell growth by inducing cell death via intrinsic apoptotic pathways. Our previous studies in clinical settings have suggested that certain subpopulations of patients with acute myeloid leukemia (AML) had poor response to chemotherapy.


METHODS
The effect of staurosporine on apoptosis and cell cycle distribution in human leukemic cell line U-937 cells was determined. U-937 cells were treated with staurosporine at 0.5 microM for 18 hours or 1 microM for 24 hours. Analyses of cell cycle distribution and apoptosis were performed using flow cytometric analysis. The effects of staurosporine on the targeted proteins were assessed by immunoblot analysis.


RESULTS
A blockade of the cell cycle at the G(2)/M phase was observed in U-937 cells treated with staurosporine. A concomitant induction of apoptosis and activation of caspase-3 in U-937 cells was also achieved. Treatment of U-937 cells with staurosporine at 1 microM for 24 hours, compared with 0.5 microM for 18 hours, appeared to kill the leukemic more efficiently cells and this dose and duration may specifically target p27, Erk and Akt pathways that are important for cancer cell survival and resistance to treatment. We also show that the effects of stauroporine on cell cycle progression and apoptosis in U-937 cells are closely linked.


CONCLUSIONS
Our results suggest that induction of apoptosis and inhibitory proliferation and survival pathways are important events induced by staurosporine. Understanding the conditions under which staurosporine shows high specificity and low toxicity in treatment of leukemic cells is of great importance for improving the efficacy of targeted therapeutics and overcoming resistance to chemotherapeutic agents.
Antonsson
Andreas
A
Division of Experimental Cancer Research, Department of Laboratory Medicine, Lund University, Clinical Research Center, 20502 Malmö, Sweden.
Persson
Jenny L
JL
D017209:Apoptosis / Q000187:drug effects*; D018797:Cell Cycle Proteins / Q000378:metabolism*; D002455:Cell Division / Q000187:drug effects*; D049109:Cell Proliferation / Q000187:drug effects; D004791:Enzyme Inhibitors / Q000494:pharmacology; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D005434:Flow Cytometry; D016195:G2 Phase / Q000187:drug effects*; D006801:Humans; D015151:Immunoblotting; D010766:Phosphorylation / Q000187:drug effects; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism*; D019311:Staurosporine / Q000494:pharmacology*; D020298:U937 Cells
D018797:Cell Cycle Proteins; D004791:Enzyme Inhibitors; D051057:Proto-Oncogene Proteins c-akt; D011493:Protein Kinase C; D048049:Extracellular Signal-Regulated MAP Kinases; D019311:Staurosporine