title: Deoxypodophyllotoxin induces G2/M cell cycle arrest and apoptosis in HeLa cells.
abstract: The natural flavolignan deoxypodophyllotoxin (DPPT) inhibits tubulin polymerization and induces cell cycle arrest at G(2)/M, followed by apoptosis. However, the precise mechanism of DPPT action is currently unknown. Here, we investigated the mechanism by which DPPT treatment of HeLa cervical carcinoma cells induces cell cycle arrest and apoptosis. We show that DPPT treatment inhibits cell viability in a dose-dependent manner and that this reduction in cell viability results from cell cycle arrest at G(2)/M phase, accompanied by an increase in apoptotic cell death. The induction of apoptosis by DPPT was confirmed by visualization of morphologic changes and internucleosomal DNA fragmentation. In addition, DPPT causes p53 and Bax to accumulate, accompanied by activation of DNA damage-sensing kinases, including ataxia-telangiectasia mutated (ATM) kinase and Chk2. Furthermore, DPPT activates caspase-3 and -7, suggesting that caspase-mediated pathways are involved in DPPT-induced apoptosis. Levels of the tumor suppressor PTEN were up-regulated during DPPT treatment, coincident with Akt inhibition. Together, these data suggest that DPPT induces G(2)/M cell-cycle arrest followed by apoptosis through multiple cellular processes, involving the activation of ATM, upregulation of p53 and Bax, activation of caspase-3 and -7, and accumulation of PTEN resulting in the inhibition of the Akt pathway.
authors.affiliation: Research Center for Transcription Control, Konkuk University, Seoul 143-701, Republic of Korea.
authors.forename: Soon Young
authors.initials: SY
authors.lastname: Shin
authors.forename: Yeonjoong
authors.initials: Y
authors.lastname: Yong
authors.forename: Chang Gun
authors.initials: CG
authors.lastname: Kim
authors.forename: Young Han
authors.initials: YH
authors.lastname: Lee
authors.forename: Yoongho
authors.initials: Y
authors.lastname: Lim
mesh_terms: D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects*; D064007:Ataxia Telangiectasia Mutated Proteins; D053148:Caspase 3 / Q000378:metabolism; D053179:Caspase 7 / Q000378:metabolism; D002453:Cell Cycle / Q000187:drug effects*; D018797:Cell Cycle Proteins / Q000378:metabolism; D002455:Cell Division; D049109:Cell Proliferation / Q000187:drug effects*; D002470:Cell Survival / Q000187:drug effects; D064447:Checkpoint Kinase 2; D053938:DNA Fragmentation; D004268:DNA-Binding Proteins / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004365:Drugs, Chinese Herbal; D004789:Enzyme Activation; D005260:Female; D016195:G2 Phase; D006367:HeLa Cells; D006801:Humans; D051059:PTEN Phosphohydrolase / Q000378:metabolism; D011034:Podophyllotoxin / Q000031:analogs & derivatives* / Q000494:pharmacology; D017346:Protein Serine-Threonine Kinases / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors / Q000378:metabolism; D015398:Signal Transduction / Q000187:drug effects; D013997:Time Factors; D050257:Tubulin Modulators / Q000494:pharmacology*; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism; D025521:Tumor Suppressor Proteins / Q000378:metabolism; D002583:Uterine Cervical Neoplasms / Q000473:pathology*; D051028:bcl-2-Associated X Protein / Q000378:metabolism
chemical_list: D000972:Antineoplastic Agents, Phytogenic; C494826:BAX protein, human; D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D004365:Drugs, Chinese Herbal; C495901:TP53 protein, human; D050257:Tubulin Modulators; D016159:Tumor Suppressor Protein p53; D025521:Tumor Suppressor Proteins; D051028:bcl-2-Associated X Protein; C014451:deoxypodophyllotoxin; D064447:Checkpoint Kinase 2; C576324:ATM protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; C578634:CHEK2 protein, human; D017346:Protein Serine-Threonine Kinases; D051057:Proto-Oncogene Proteins c-akt; D051059:PTEN Phosphohydrolase; C494929:PTEN protein, human; C505407:CASP3 protein, human; C505520:CASP7 protein, human; D053148:Caspase 3; D053179:Caspase 7; D011034:Podophyllotoxin