title: Critical role of cyclin B1/Cdc2 up-regulation in the induction of mitotic prometaphase arrest in human breast cancer cells treated with 2-methoxyestradiol.
abstract: Earlier studies showed that 2-methoxyestradiol (2ME(2)), an endogenous nonpolar metabolite of estradiol-17β, is a strong inducer of G(2)/M cell cycle arrest (based on analysis of cellular DNA content) in human cancer cell lines. The present study sought to investigate the molecular mechanism underlying 2ME(2)-induced cell cycle arrest. We found that 2ME(2) can selectively induce mitotic prometaphase arrest, but not G(2) phase arrest, in cultured MDA-MB-435s and MCF-7 human breast cancer cells. During the induction of prometaphase arrest, there is a time-dependent initial up-regulation of cyclin B1 and Cdc2 proteins, occurring around 12-24h. The strong initial up-regulation of cyclin B1 and Cdc2 matches in timing the 2ME(2)-induced prometaphase arrest. The 2ME(2)-induced prometaphase arrest is abrogated by selective knockdown of cyclin B1 and Cdc2, or by pre-treatment of cells with roscovitine, an inhibitor of cyclin-dependent kinases, or by co-treatment of cells with cycloheximide, a protein synthesis inhibitor that was found to suppress the early up-regulation of cyclin B1 and Cdc2. In addition, we provided evidence showing that MAD2 and JNK1 are important upstream mediators of 2ME(2)-induced up-regulation of cyclin B1 and Cdc2 as well as the subsequent induction of mitotic prometaphase arrest. In conclusion, treatment of human cancer cells with 2ME(2) causes up-regulation of cyclin B1 and Cdc2, which then mediate the induction of mitotic prometaphase arrest.
authors.affiliation: Department of Pharmacology, University of Kansas Medical Center, Kansas City, KS, USA.
authors.forename: Hye Joung
authors.initials: HJ
authors.lastname: Choi
authors.forename: Bao Ting
authors.initials: BT
authors.lastname: Zhu
mesh_terms: D000077584:2-Methoxyestradiol; D000970:Antineoplastic Agents / Q000494:pharmacology*; D001943:Breast Neoplasms; D016203:CDC2 Protein Kinase; D002135:Calcium-Binding Proteins / Q000378:metabolism; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D053144:Cell Nucleus Shape / Q000187:drug effects; D019926:Cyclin B / Q000235:genetics* / Q000378:metabolism; D056744:Cyclin B1 / Q000235:genetics* / Q000378:metabolism; D018844:Cyclin-Dependent Kinases; D004958:Estradiol / Q000031:analogs & derivatives* / Q000494:pharmacology; D005260:Female; D059565:G2 Phase Cell Cycle Checkpoints / Q000187:drug effects; D055785:Gene Knockdown Techniques; D006801:Humans; D064246:Mad2 Proteins; D048055:Mitogen-Activated Protein Kinase 8 / Q000378:metabolism; D049468:Prometaphase / Q000187:drug effects*; D034622:RNA Interference; D012097:Repressor Proteins / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects*
chemical_list: D000970:Antineoplastic Agents; C534699:CCNB1 protein, human; D002135:Calcium-Binding Proteins; D018797:Cell Cycle Proteins; D019926:Cyclin B; D056744:Cyclin B1; C577697:MAD2L1 protein, human; D064246:Mad2 Proteins; D012097:Repressor Proteins; D004958:Estradiol; D000077584:2-Methoxyestradiol; D016203:CDC2 Protein Kinase; C528899:CDK1 protein, human; D018844:Cyclin-Dependent Kinases; D048055:Mitogen-Activated Protein Kinase 8