Paclitaxel induced apoptosis in breast cancer cells requires cell cycle transit but not Cdc2 activity.
OBJECTIVE
Paclitaxel (PTX) is a widely used chemotherapy agent and may cause cell death by apoptosis subsequent to microtubule (MT) disruption. In this paper, we have investigated whether cell cycle transit and or Cdc2 (Cdk1) activity is required for the apoptosis induced by PTX.


METHODS
Cell cycle was analyzed by flow cytometry, Cdc2 was assayed bio chemically. Cdc2 activity was decreased by siRNA and dominant negative (dn) Cdc2 expression. Cells were arrested by chemical or biological inhibitors in a G1 or S phase. Apoptosis was measured by DNA fragmentation and examination of nuclei by microscopy. JNK and AKT activations were assessed as well.


RESULTS
Cell cycle inhibition was highly effective in decreasing PTX induced apoptosis. MT morphology was not altered by these inhibitors. PTX induced JNK activity or AKT mediated BAD phosphorylation was unaffected by cell cycle inhibitors. Abrogation of Cdc 2 activity was without effect on PTX induced apoptosis.


CONCLUSIONS
While cell cycle transit is required for PTX induced apoptosis; Cdc2 activity is not required.
Henley
D
D
Department of OB/GYN, GSM, UTMCK, University of Tennessee, Alcoa Highway, Knoxville, TN 37920, USA.
Isbill
M
M
Fernando
R
R
Foster
J S
JS
Wimalasena
J
J
D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology; D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D001943:Breast Neoplasms / Q000378:metabolism / Q000473:pathology / Q000503:physiopathology; D016203:CDC2 Protein Kinase / Q000235:genetics / Q000378:metabolism*; D002453:Cell Cycle / Q000187:drug effects*; D045744:Cell Line, Tumor; D002467:Cell Nucleus / Q000187:drug effects / Q000378:metabolism; D002470:Cell Survival / Q000187:drug effects; D053938:DNA Fragmentation / Q000187:drug effects; D004958:Estradiol / Q000031:analogs & derivatives / Q000494:pharmacology; D005434:Flow Cytometry; D000077267:Fulvestrant; D006801:Humans; D006918:Hydroxyurea / Q000494:pharmacology; D051034:Inhibitor of Apoptosis Proteins; D048031:JNK Mitogen-Activated Protein Kinases / Q000037:antagonists & inhibitors / Q000378:metabolism; D008869:Microtubule-Associated Proteins / Q000378:metabolism; D008870:Microtubules / Q000187:drug effects; D009363:Neoplasm Proteins / Q000378:metabolism; D017239:Paclitaxel / Q000494:pharmacology*; D011687:Purines / Q000494:pharmacology; D034741:RNA, Small Interfering / Q000235:genetics; D000077546:Roscovitine; D008941:Spindle Apparatus / Q000187:drug effects / Q000378:metabolism; D000077022:Survivin; D013936:Thymidine / Q000494:pharmacology; D014162:Transfection; D051025:bcl-Associated Death Protein / Q000378:metabolism
D000972:Antineoplastic Agents, Phytogenic; C494819:BAD protein, human; C107489:BIRC5 protein, human; D051034:Inhibitor of Apoptosis Proteins; D008869:Microtubule-Associated Proteins; D009363:Neoplasm Proteins; D011687:Purines; D034741:RNA, Small Interfering; D000077022:Survivin; D051025:bcl-Associated Death Protein; D000077546:Roscovitine; D000077267:Fulvestrant; D004958:Estradiol; D016203:CDC2 Protein Kinase; D048031:JNK Mitogen-Activated Protein Kinases; D017239:Paclitaxel; D013936:Thymidine; D006918:Hydroxyurea