title: Functional characterization of the 19q12 amplicon in grade III breast cancers.
abstract: BACKGROUND
  The 19q12 locus is amplified in a subgroup of oestrogen receptor (ER)-negative grade III breast cancers. This amplicon comprises nine genes, including cyclin E1 (CCNE1), which has been proposed as its 'driver'. The aim of this study was to identify the genes within the 19q12 amplicon whose expression is required for the survival of cancer cells harbouring their amplification.
  
  
  METHODS
  We investigated the presence of 19q12 amplification in a series of 313 frozen primary breast cancers and 56 breast cancer cell lines using microarray comparative genomic hybridisation (aCGH). The nine genes mapping to the smallest region of amplification on 19q12 were silenced using RNA interference in phenotypically matched breast cancer cell lines with (MDA-MB-157 and HCC1569) and without (Hs578T, MCF7, MDA-MB-231, ZR75.1, JIMT1 and BT474) amplification of this locus. Genes whose silencing was selectively lethal in amplified cells were taken forward for further validation. The effects of cyclin-dependent kinase 2 (CDK2) silencing and chemical inhibition were tested in cancer cells with and without CCNE1 amplification.
  
  
  RESULTS
  19q12 amplification was identified in 7.8% of ER-negative grade III breast cancer. Of the nine genes mapping to this amplicon, UQCRFS1, POP4, PLEKHF1, C19ORF12, CCNE1 and C19ORF2 were significantly over-expressed when amplified in primary breast cancers and/or breast cancer cell lines. Silencing of POP4, PLEKHF1, CCNE1 and TSZH3 selectively reduced cell viability in cancer cells harbouring their amplification. Cancer cells with CCNE1 amplification were shown to be dependent on CDK2 expression and kinase activity for their survival.
  
  
  CONCLUSIONS
  The 19q12 amplicon may harbour more than a single 'driver', given that expression of POP4, PLEKHF1, CCNE1 and TSZH3 is required for the survival of cancer cells displaying their amplification. The observation that cancer cells harbouring CCNE1 gene amplification are sensitive to CDK2 inhibitors provides a rationale for the testing of these chemical inhibitors in a subgroup of patients with ER-negative grade III breast cancers.
authors.affiliation: Breakthrough Breast Cancer Research Centre, The Institute of Cancer Research, 237 Fulham Road, London, SW3 6JB, UK.
authors.forename: Rachael
authors.initials: R
authors.lastname: Natrajan
authors.forename: Alan
authors.initials: A
authors.lastname: Mackay
authors.forename: Paul M
authors.initials: PM
authors.lastname: Wilkerson
authors.forename: Maryou B
authors.initials: MB
authors.lastname: Lambros
authors.forename: Daniel
authors.initials: D
authors.lastname: Wetterskog
authors.forename: Monica
authors.initials: M
authors.lastname: Arnedos
authors.forename: Kai-Keen
authors.initials: KK
authors.lastname: Shiu
authors.forename: Felipe C
authors.initials: FC
authors.lastname: Geyer
authors.forename: Anita
authors.initials: A
authors.lastname: Langerød
authors.forename: Bas
authors.initials: B
authors.lastname: Kreike
authors.forename: Fabien
authors.initials: F
authors.lastname: Reyal
authors.forename: Hugo M
authors.initials: HM
authors.lastname: Horlings
authors.forename: Marc J
authors.initials: MJ
authors.lastname: van de Vijver
authors.forename: Jose
authors.initials: J
authors.lastname: Palacios
authors.forename: Britta
authors.initials: B
authors.lastname: Weigelt
authors.forename: Jorge S
authors.initials: JS
authors.lastname: Reis-Filho
mesh_terms: D051017:Apoptosis Regulatory Proteins / Q000235:genetics; D001943:Breast Neoplasms / Q000235:genetics* / Q000378:metabolism / Q000473:pathology*; D045744:Cell Line, Tumor; D002888:Chromosomes, Human, Pair 19; D019927:Cyclin E / Q000235:genetics; D051357:Cyclin-Dependent Kinase 2 / Q000235:genetics; D005260:Female; D005784:Gene Amplification; D015972:Gene Expression Regulation, Neoplastic; D018398:Homeodomain Proteins / Q000235:genetics; D006801:Humans; D060787:Neoplasm Grading; D015513:Oncogene Proteins / Q000235:genetics; D034622:RNA Interference; D011960:Receptors, Estrogen / Q000378:metabolism; D012260:Ribonucleases / Q000235:genetics; D012261:Ribonucleoproteins / Q000235:genetics
chemical_list: D051017:Apoptosis Regulatory Proteins; C475820:CCNE1 protein, human; D019927:Cyclin E; D018398:Homeodomain Proteins; D015513:Oncogene Proteins; C508358:PLEKHF1 protein, human; D011960:Receptors, Estrogen; D012261:Ribonucleoproteins; C580600:TSHZ3 protein, human; C495894:CDK2 protein, human; D051357:Cyclin-Dependent Kinase 2; D012260:Ribonucleases; C105253:POP4 protein, human