title: Association of a microRNA/TP53 feedback circuitry with pathogenesis and outcome of B-cell chronic lymphocytic leukemia.
abstract: BACKGROUND
  Chromosomal abnormalities (namely 13q, 17p, and 11q deletions) have prognostic implications and are recurrent in chronic lymphocytic leukemia (CLL), suggesting that they are involved in a common pathogenetic pathway; however, the molecular mechanism through which chromosomal abnormalities affect the pathogenesis and outcome of CLL is unknown.
  
  
  OBJECTIVE
  To determine whether the microRNA miR-15a/miR-16-1 cluster (located at 13q), tumor protein p53 (TP53, located at 17p), and miR-34b/miR-34c cluster (located at 11q) are linked in a molecular pathway that explains the pathogenetic and prognostic implications (indolent vs aggressive form) of recurrent 13q, 17p, and 11q deletions in CLL.
  
  
  METHODS
  CLL Research Consortium institutions provided blood samples from untreated patients (n = 206) diagnosed with B-cell CLL between January 2000 and April 2008. All samples were evaluated for the occurrence of cytogenetic abnormalities as well as the expression levels of the miR-15a/miR-16-1 cluster, miR-34b/miR-34c cluster, TP53, and zeta-chain (TCR)-associated protein kinase 70 kDa (ZAP70), a surrogate prognostic marker of CLL. The functional relationship between these genes was studied using in vitro gain- and loss-of-function experiments in cell lines and primary samples and was validated in a separate cohort of primary CLL samples.
  
  
  METHODS
  Cytogenetic abnormalities; expression levels of the miR-15a/miR-16-1 cluster, miR-34 family, TP53 gene, downstream effectors cyclin-dependent kinase inhibitor 1A (p21, Cip1) (CDKN1A) and B-cell CLL/lymphoma 2 binding component 3 (BBC3), and ZAP70 gene; genetic interactions detected by chromatin immunoprecipitation.
  
  
  RESULTS
  In CLLs with 13q deletions the miR-15a/miR-16-1 cluster directly targeted TP53 (mean luciferase activity for miR-15a vs scrambled control, 0.68 relative light units (RLU) [95% confidence interval {CI}, 0.63-0.73]; P = .02; mean for miR-16 vs scrambled control, 0.62 RLU [95% CI, 0.59-0.65]; P = .02) and its downstream effectors. In leukemic cell lines and primary CLL cells, TP53 stimulated the transcription of miR-15/miR-16-1 as well as miR-34b/miR-34c clusters, and the miR-34b/miR-34c cluster directly targeted the ZAP70 kinase (mean luciferase activity for miR-34a vs scrambled control, 0.33 RLU [95% CI, 0.30-0.36]; P = .02; mean for miR-34b vs scrambled control, 0.31 RLU [95% CI, 0.30-0.32]; P = .01; and mean for miR-34c vs scrambled control, 0.35 RLU [95% CI, 0.33-0.37]; P = .02).
  
  
  CONCLUSIONS
  A microRNA/TP53 feedback circuitry is associated with CLL pathogenesis and outcome. This mechanism provides a novel pathogenetic model for the association of 13q deletions with the indolent form of CLL that involves microRNAs, TP53, and ZAP70.
authors.forename: Muller
authors.initials: M
authors.lastname: Fabbri
authors.forename: Arianna
authors.initials: A
authors.lastname: Bottoni
authors.forename: Masayoshi
authors.initials: M
authors.lastname: Shimizu
authors.forename: Riccardo
authors.initials: R
authors.lastname: Spizzo
authors.forename: Milena S
authors.initials: MS
authors.lastname: Nicoloso
authors.forename: Simona
authors.initials: S
authors.lastname: Rossi
authors.forename: Elisa
authors.initials: E
authors.lastname: Barbarotto
authors.forename: Amelia
authors.initials: A
authors.lastname: Cimmino
authors.forename: Brett
authors.initials: B
authors.lastname: Adair
authors.forename: Sylwia E
authors.initials: SE
authors.lastname: Wojcik
authors.forename: Nicola
authors.initials: N
authors.lastname: Valeri
authors.forename: Federica
authors.initials: F
authors.lastname: Calore
authors.forename: Deepa
authors.initials: D
authors.lastname: Sampath
authors.forename: Francesca
authors.initials: F
authors.lastname: Fanini
authors.forename: Ivan
authors.initials: I
authors.lastname: Vannini
authors.forename: Gerardo
authors.initials: G
authors.lastname: Musuraca
authors.forename: Marie
authors.initials: M
authors.lastname: Dell'Aquila
authors.forename: Hansjuerg
authors.initials: H
authors.lastname: Alder
authors.forename: Ramana V
authors.initials: RV
authors.lastname: Davuluri
authors.forename: Laura Z
authors.initials: LZ
authors.lastname: Rassenti
authors.forename: Massimo
authors.initials: M
authors.lastname: Negrini
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Nakamura
authors.forename: Dino
authors.initials: D
authors.lastname: Amadori
authors.forename: Neil E
authors.initials: NE
authors.lastname: Kay
authors.forename: Kanti R
authors.initials: KR
authors.lastname: Rai
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Keating
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Kipps
authors.forename: George A
authors.initials: GA
authors.lastname: Calin
authors.forename: Carlo M
authors.initials: CM
authors.lastname: Croce
mesh_terms: D000328:Adult; D000368:Aged; D002872:Chromosome Deletion; D002880:Chromosomes, Human, Pair 11 / Q000235:genetics; D002882:Chromosomes, Human, Pair 13 / Q000235:genetics; D002886:Chromosomes, Human, Pair 17 / Q000235:genetics; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D016158:Genes, p53 / Q000235:genetics*; D006801:Humans; D015451:Leukemia, Lymphocytic, Chronic, B-Cell / Q000235:genetics* / Q000473:pathology*; D008297:Male; D035683:MicroRNAs / Q000235:genetics*; D008875:Middle Aged; D011379:Prognosis; D014158:Transcription, Genetic; D016159:Tumor Suppressor Protein p53 / Q000502:physiology; D051746:ZAP-70 Protein-Tyrosine Kinase / Q000502:physiology
chemical_list: D035683:MicroRNAs; D016159:Tumor Suppressor Protein p53; D051746:ZAP-70 Protein-Tyrosine Kinase; C497261:ZAP70 protein, human