title: Tubulozole-induced G2/M cell cycle arrest in human colon cancer cells through formation of microtubule polymerization mediated by ERK1/2 and Chk1 kinase activation.
abstract: Our studies demonstrated that human colon cancer cells (COLO 205), with higher expression level of check point kinase 1 (Chk1), were more sensitive to microtubule damage agent Tubulozole (TUBU) induced G2/M phase arrest than normal human colon epithelial (CRL) cells. TUBU (10 microM, for 3h) treatment resulted in rapid and sustained phosphorylation of Cdc25C (Ser-216) leading to increased 14-3-3beta binding. This resulted in increased nuclear translocation. In addition, TUBU induced phosphorylation of the Cdc25C (Ser-216) and Bad (Ser-155) proteins were blocked by Chk1 SiRNA-transfection. Surprisingly, cellular apotosis was observed in cells treated with TUBU after Chk1 SiRNA inhibition. We further demonstrated that extracellular signal-regulated kinase (ERK) activation by TUBU was needed for Chk1 kinase activation and microtubule formation as shown by the attenuation of these responses by the ERK1/2 specific inhibitor PD98059. However, TUBU induced ERK1/2 phosphorylation was not blocked in the Chk1 SiRNA-transfected COLO 205 cells. These results imply that ERK1/2 mediated Chk1 activation may be play an important role in determining TUBU induced G2/M arrest or apoptosis in COLO 205 cells.
authors.affiliation: Department of Surgery, Division of General Surgery, School of Medicine, Taipei Medical University and Hospital, No. 252 Wu-Hsing Street, Taipei 110, Taiwan.
authors.forename: Yean-Hwei
authors.initials: YH
authors.lastname: Chou
authors.forename: Yuan-Soon
authors.initials: YS
authors.lastname: Ho
authors.forename: Chi-Chen
authors.initials: CC
authors.lastname: Wu
authors.forename: Chiah-Yang
authors.initials: CY
authors.lastname: Chai
authors.forename: Soul-Chin
authors.initials: SC
authors.lastname: Chen
authors.forename: Chia-Hwa
authors.initials: CH
authors.lastname: Lee
authors.forename: Pei-Shan
authors.initials: PS
authors.lastname: Tsai
authors.forename: Chih-Hsiung
authors.initials: CH
authors.lastname: Wu
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D017209:Apoptosis / Q000187:drug effects; D015153:Blotting, Western; D002453:Cell Cycle / Q000187:drug effects*; D002455:Cell Division / Q000187:drug effects; D049109:Cell Proliferation / Q000187:drug effects; D000071877:Checkpoint Kinase 1; D003110:Colonic Neoplasms / Q000188:drug therapy* / Q000201:enzymology / Q000473:pathology; D004148:Dioxolanes / Q000494:pharmacology*; D004789:Enzyme Activation / Q000187:drug effects; D048049:Extracellular Signal-Regulated MAP Kinases / Q000378:metabolism*; D005434:Flow Cytometry; D016195:G2 Phase / Q000187:drug effects; D018922:HL-60 Cells; D019073:HT29 Cells; D006801:Humans; D008870:Microtubules / Q000187:drug effects* / Q000378:metabolism; D010766:Phosphorylation / Q000187:drug effects; D011494:Protein Kinases / Q000378:metabolism*; D034741:RNA, Small Interfering / Q000502:physiology
chemical_list: D000970:Antineoplastic Agents; D004148:Dioxolanes; D034741:RNA, Small Interfering; C040422:tubulazole; D011494:Protein Kinases; C000605867:CHEK1 protein, human; D000071877:Checkpoint Kinase 1; D048049:Extracellular Signal-Regulated MAP Kinases