title: Norcantharidin inhibits DNA replication and induces mitotic catastrophe by degrading initiation protein Cdc6.
abstract: Cdc6, an essential initiation protein for DNA replication, also participates in the ATR checkpoint pathway and plays a vital role in tumorigenesis. It is involved in the androgen receptor (AR) signal transduction and promotes the malignant progression of prostate cancer (PCa). In this study, we report that norcantharidin (NCTD) induces the degradation of Cdc6 in DU145 PCa cells and as a result, the assembly of pre-replication complexes (pre-RCs) was disturbed and DNA replication was inhibited. Furthermore, treatment with NCTD blocked ATR binding to chromatin and the cells progressed into mitosis under stress induced by hydroxyurea (HU), indicating that the ATR checkpoint was evaded. Aberrant mitosis and hence, apoptosis were also observed following treatment with NCTD. Finally, NCTD exerted strong synergistic cytotoxic effects in combination with another mitotic inhibitor, paclitaxel, [combination index (CI <1)]. These data suggest that NCTD not only inhibits DNA replication but also disables the ATR-dependent checkpoint pathway by inducing Cdc6 degradation, which leads to mitotic catastrophe in DU145 cells. These findings also provide a promising prospect for the combination treatment of paclitaxel and NCTD or Cdc6 deletion in PCa.
authors.affiliation: Institute of Biotherapy, School of Biotechnology, Southern Medical University, Guangzhou, Guangdong 510515, P.R. China.
authors.forename: Sansan
authors.initials: S
authors.lastname: Chen
authors.forename: Pei
authors.initials: P
authors.lastname: Wan
authors.forename: Wen
authors.initials: W
authors.lastname: Ding
authors.forename: Fei
authors.initials: F
authors.lastname: Li
authors.forename: Chengwu
authors.initials: C
authors.lastname: He
authors.forename: Pengliang
authors.initials: P
authors.lastname: Chen
authors.forename: Hongwei
authors.initials: H
authors.lastname: Li
authors.forename: Zhiming
authors.initials: Z
authors.lastname: Hu
authors.forename: Wanlong
authors.initials: W
authors.lastname: Tan
authors.forename: Jinlong
authors.initials: J
authors.lastname: Li
mesh_terms: D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology; D064007:Ataxia Telangiectasia Mutated Proteins / Q000378:metabolism; D019086:Bridged Bicyclo Compounds, Heterocyclic / Q000494:pharmacology*; D018797:Cell Cycle Proteins / Q000378:metabolism*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002843:Chromatin / Q000378:metabolism; D004261:DNA Replication / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004357:Drug Synergism; D016193:G1 Phase / Q000187:drug effects; D006801:Humans; D059566:M Phase Cell Cycle Checkpoints / Q000187:drug effects; D008938:Mitosis / Q000187:drug effects*; D009687:Nuclear Proteins / Q000378:metabolism*; D017239:Paclitaxel / Q000494:pharmacology; D011485:Protein Binding / Q000187:drug effects; D059748:Proteolysis / Q000187:drug effects; D059807:S Phase Cell Cycle Checkpoints / Q000187:drug effects
chemical_list: D000972:Antineoplastic Agents, Phytogenic; D019086:Bridged Bicyclo Compounds, Heterocyclic; C103706:CDC6 protein, human; D018797:Cell Cycle Proteins; D002843:Chromatin; D009687:Nuclear Proteins; C069741:norcantharidin; C576597:ATR protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; D017239:Paclitaxel