title: Resistance to CDK2 inhibitors is associated with selection of polyploid cells in CCNE1-amplified ovarian cancer.
abstract: OBJECTIVE
  Amplification of cyclin E1 (CCNE1) is associated with poor outcome in breast, lung, and other solid cancers, and is the most prominent structural variant associated with primary treatment failure in high-grade serous ovarian cancer (HGSC). We have previously shown that CCNE1-amplified tumors show amplicon-dependent sensitivity to CCNE1 suppression. Here, we explore targeting CDK2 as a novel therapeutic strategy in CCNE1-amplified cancers and mechanisms of resistance.
  
  
  METHODS
  We examined the effect of CDK2 suppression using RNA interference and small-molecule inhibitors in SK-OV-3, OVCAR-4, and OVCAR-3 ovarian cancer cell lines. To identify mechanisms of resistance, we derived multiple, independent resistant sublines of OVCAR-3 to CDK2 inhibitors. Resistant cells were extensively characterized by gene expression and copy number analysis, fluorescence-activated cell sorting profiling and conventional karyotyping. In addition, we explored the relationship between CCNE1 amplification and polyploidy using data from primary tumors.
  
  
  RESULTS
  We validate CDK2 as a therapeutic target in CCNE1-amplified cells by showing selective sensitivity to suppression, either by gene knockdown or using small-molecule inhibitors. In addition, we identified two resistance mechanisms, one involving upregulation of CDK2 and another novel mechanism involving selection of polyploid cells from the pretreatment tumor population. Our analysis of genomic data shows that polyploidy is a feature of cancer genomes with CCNE1 amplification.
  
  
  CONCLUSIONS
  These findings suggest that cyclinE1/CDK2 is an important therapeutic target in HGSC, but that resistance to CDK2 inhibitors may emerge due to upregulation of CDK2 target protein and through preexisting cellular polyploidy.
authors.affiliation: Authors' Affiliations: Peter MacCallum Cancer Centre, East Melbourne; Victorian Cancer Cytogenetics Service, St Vincent's Hospital, Melbourne; Sir Peter MacCallum Department of Oncology; Departments of Pathology, Biochemistry and Molecular Biology, and Medicine; Centre for Translational Pathology, University of Melbourne, Parkville, Victoria, Australia; Dana-Farber Cancer Institute, Boston; and The Broad Institute of Harvard and MIT, Cambridge, Massachusetts.
authors.forename: Dariush
authors.initials: D
authors.lastname: Etemadmoghadam
authors.forename: George
authors.initials: G
authors.lastname: Au-Yeung
authors.forename: Meaghan
authors.initials: M
authors.lastname: Wall
authors.forename: Chris
authors.initials: C
authors.lastname: Mitchell
authors.forename: Maya
authors.initials: M
authors.lastname: Kansara
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Loehrer
authors.forename: Crisoula
authors.initials: C
authors.lastname: Batzios
authors.forename: Joshy
authors.initials: J
authors.lastname: George
authors.forename: Sarah
authors.initials: S
authors.lastname: Ftouni
authors.forename: Barbara A
authors.initials: BA
authors.lastname: Weir
authors.forename: Scott
authors.initials: S
authors.lastname: Carter
authors.forename: Irma
authors.initials: I
authors.lastname: Gresshoff
authors.forename: Linda
authors.initials: L
authors.lastname: Mileshkin
authors.forename: Danny
authors.initials: D
authors.lastname: Rischin
authors.forename: William C
authors.initials: WC
authors.lastname: Hahn
authors.forename: Paul M
authors.initials: PM
authors.lastname: Waring
authors.forename: Gad
authors.initials: G
authors.lastname: Getz
authors.forename: Carleen
authors.initials: C
authors.lastname: Cullinane
authors.forename: Lynda J
authors.initials: LJ
authors.lastname: Campbell
authors.forename: David D
authors.initials: DD
authors.lastname: Bowtell
mesh_terms: D045744:Cell Line, Tumor; D002470:Cell Survival / Q000235:genetics; D016000:Cluster Analysis; D019927:Cyclin E / Q000235:genetics*; D051357:Cyclin-Dependent Kinase 2 / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D019008:Drug Resistance, Neoplasm / Q000235:genetics*; D005260:Female; D005784:Gene Amplification; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D015513:Oncogene Proteins / Q000235:genetics*; D010051:Ovarian Neoplasms / Q000235:genetics* / Q000378:metabolism; D011123:Polyploidy; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D011720:Pyrazoles / Q000494:pharmacology; D011760:Pyrrolidinones / Q000494:pharmacology
chemical_list: C475820:CCNE1 protein, human; D019927:Cyclin E; C500624:N-(5-cyclopropyl-1H-pyrazol-3-yl)-2-(4-(2-oxo-1-pyrrolidinyl)phenyl)propanamide; D015513:Oncogene Proteins; D047428:Protein Kinase Inhibitors; D011720:Pyrazoles; D011760:Pyrrolidinones; D051357:Cyclin-Dependent Kinase 2