title: Induction of mitotic cell death by overriding G2/M checkpoint in endometrial cancer cells with non-functional p53.
abstract: OBJECTIVE
  Endometrial tumors with non-functional p53, such as serous uterine endometrial carcinomas, are aggressive malignancies with a poor outcome, yet they have an Achilles' heel: due to loss of p53 function, these tumors may be sensitive to treatments which abrogate the G2/M checkpoint. Our objective was to exploit this weakness to induce mitotic cell death using two strategies: (1) EGFR inhibitor gefitinib combined with paclitaxel to arrest cells at mitosis, or (2) BI2536, an inhibitor of polo-like kinase 1 (PLK1), to block PLK1 activity.
  
  
  METHODS
  We examined the impact of combining gefitinib and paclitaxel or PLK1 inhibitor on expression of G2/M checkpoint controllers, cell viability, and cell cycle progression in endometrial cancer cells with mutant p53.
  
  
  RESULTS
  In cells lacking normal p53 activity, each treatment activated CDC25C and inactivated Wee1, which in turn activated cdc2 and sent cells rapidly through the G2/M checkpoint and into mitosis. Live cell imaging demonstrated irreversible mitotic arrest and eventual cell death. Combinatorial therapy with paclitaxel and gefitinib was highly synergistic and resulted in a 10-fold reduction in the IC50 for paclitaxel, from 14nM as a single agent to 1.3nM in the presence of gefitinib. However, BI2536 alone at low concentrations (5nM) was the most effective treatment and resulted in massive mitotic cell death. In a xenograft mouse model with p53-deficient cells, low dose BI2536 significantly inhibited tumor growth.
  
  
  CONCLUSIONS
  These findings reveal induction of mitotic cell death as a therapeutic strategy for endometrial tumors lacking functional p53.
authors.affiliation: Department of Obstetrics and Gynecology, University of Iowa, Iowa City, IA 52242, USA. Xiangbing-meng@uiowa.edu
authors.forename: Xiangbing
authors.initials: X
authors.lastname: Meng
authors.forename: Laura L
authors.initials: LL
authors.lastname: Laidler
authors.forename: Elizabeth A
authors.initials: EA
authors.lastname: Kosmacek
authors.forename: Shujie
authors.initials: S
authors.lastname: Yang
authors.forename: Zhi
authors.initials: Z
authors.lastname: Xiong
authors.forename: Danlin
authors.initials: D
authors.lastname: Zhu
authors.forename: Xinjun
authors.initials: X
authors.lastname: Wang
authors.forename: Donghai
authors.initials: D
authors.lastname: Dai
authors.forename: Yuping
authors.initials: Y
authors.lastname: Zhang
authors.forename: Xiaofang
authors.initials: X
authors.lastname: Wang
authors.forename: Pavla
authors.initials: P
authors.lastname: Brachova
authors.forename: Lina
authors.initials: L
authors.lastname: Albitar
authors.forename: Dawei
authors.initials: D
authors.lastname: Liu
authors.forename: Fiorenza
authors.initials: F
authors.lastname: Ianzini
authors.forename: Michael A
authors.initials: MA
authors.lastname: Mackey
authors.forename: Kimberly K
authors.initials: KK
authors.lastname: Leslie
mesh_terms: D000818:Animals; D000971:Antineoplastic Combined Chemotherapy Protocols / Q000494:pharmacology*; D059447:Cell Cycle Checkpoints / Q000187:drug effects*; D016923:Cell Death / Q000187:drug effects / Q000235:genetics; D045744:Cell Line, Tumor; D016889:Endometrial Neoplasms / Q000188:drug therapy* / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D005260:Female; D059565:G2 Phase Cell Cycle Checkpoints / Q000187:drug effects; D000077156:Gefitinib; D006801:Humans; D059566:M Phase Cell Cycle Checkpoints / Q000187:drug effects; D051379:Mice; D008819:Mice, Nude; D008938:Mitosis / Q000187:drug effects* / Q000235:genetics; D017239:Paclitaxel / Q000008:administration & dosage / Q000494:pharmacology*; D011621:Pteridines / Q000008:administration & dosage / Q000494:pharmacology*; D011799:Quinazolines / Q000008:administration & dosage / Q000494:pharmacology*; D016159:Tumor Suppressor Protein p53 / Q000235:genetics* / Q000378:metabolism; D023041:Xenograft Model Antitumor Assays
chemical_list: C518477:BI 2536; D011621:Pteridines; D011799:Quinazolines; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; D017239:Paclitaxel; D000077156:Gefitinib