title: Dicer, Drosha, and outcomes in patients with ovarian cancer.
abstract: BACKGROUND
  We studied Dicer and Drosha, components of the RNA-interference machinery, in ovarian cancer.
  
  
  METHODS
  We measured messenger RNA (mRNA) levels of Dicer and Drosha in specimens of invasive epithelial ovarian cancer from 111 patients, using a quantitative reverse-transcriptase-polymerase-chain-reaction assay, and compared the results with clinical outcomes. Validation was performed with the use of published microarray data from cohorts of patients with ovarian, breast, and lung cancer. Mutational analyses of genomic DNA from the Dicer and Drosha genes were performed in a subgroup of ovarian-cancer specimens. Dicer-dependent functional assays were performed by means of in vitro transfection with small interfering RNA (siRNA) and short hairpin RNA (shRNA).
  
  
  RESULTS
  Levels of Dicer and Drosha mRNA correlated with the levels of expression of the corresponding protein and were decreased in 60% and 51% of ovarian-cancer specimens, respectively. Low Dicer expression was significantly associated with advanced tumor stage (P=0.007), and low Drosha expression with suboptimal surgical cytoreduction (P=0.02). Cancer specimens with both high Dicer expression and high Drosha expression were associated with increased median survival (>11 years, vs. 2.66 years for other subgroups; P<0.001). We found three independent predictors of reduced disease-specific survival in multivariate analyses: low Dicer expression (hazard ratio, 2.10; P=0.02), high-grade histologic features (hazard ratio, 2.46; P=0.03), and poor response to chemotherapy (hazard ratio, 3.95; P<0.001). Poor clinical outcomes among patients with low Dicer expression were validated in additional cohorts of patients. Rare missense mutations were found in the Dicer and Drosha genes, but their presence or absence did not correlate with the level of expression. Functional assays indicated that gene silencing with shRNA, but not siRNA, may be impaired in cells with low Dicer expression.
  
  
  CONCLUSIONS
  Our findings indicate that levels of Dicer and Drosha mRNA in ovarian-cancer cells have associations with outcomes in patients with ovarian cancer.
authors.affiliation: University of Texas M.D. Anderson Cancer Center, Houston, TX 77230, USA.
authors.forename: William M
authors.initials: WM
authors.lastname: Merritt
authors.forename: Yvonne G
authors.initials: YG
authors.lastname: Lin
authors.forename: Liz Y
authors.initials: LY
authors.lastname: Han
authors.forename: Aparna A
authors.initials: AA
authors.lastname: Kamat
authors.forename: Whitney A
authors.initials: WA
authors.lastname: Spannuth
authors.forename: Rosemarie
authors.initials: R
authors.lastname: Schmandt
authors.forename: Diana
authors.initials: D
authors.lastname: Urbauer
authors.forename: Len A
authors.initials: LA
authors.lastname: Pennacchio
authors.forename: Jan-Fang
authors.initials: JF
authors.lastname: Cheng
authors.forename: Alpa M
authors.initials: AM
authors.lastname: Nick
authors.forename: Michael T
authors.initials: MT
authors.lastname: Deavers
authors.forename: Alexandra
authors.initials: A
authors.lastname: Mourad-Zeidan
authors.forename: Hua
authors.initials: H
authors.lastname: Wang
authors.forename: Peter
authors.initials: P
authors.lastname: Mueller
authors.forename: Marc E
authors.initials: ME
authors.lastname: Lenburg
authors.forename: Joe W
authors.initials: JW
authors.lastname: Gray
authors.forename: Samuel
authors.initials: S
authors.lastname: Mok
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Birrer
authors.forename: Gabriel
authors.initials: G
authors.lastname: Lopez-Berestein
authors.forename: Robert L
authors.initials: RL
authors.lastname: Coleman
authors.forename: Menashe
authors.initials: M
authors.lastname: Bar-Eli
authors.forename: Anil K
authors.initials: AK
authors.lastname: Sood
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001943:Breast Neoplasms / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D053487:DEAD-box RNA Helicases / Q000235:genetics / Q000378:metabolism*; D004252:DNA Mutational Analysis; D004722:Endoribonucleases / Q000235:genetics / Q000378:metabolism*; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D053208:Kaplan-Meier Estimate; D008175:Lung Neoplasms / Q000235:genetics / Q000378:metabolism; D035683:MicroRNAs / Q000378:metabolism; D008875:Middle Aged; D015999:Multivariate Analysis; D020125:Mutation, Missense; D009367:Neoplasm Staging; D009375:Neoplasms, Glandular and Epithelial / Q000235:genetics / Q000378:metabolism* / Q000401:mortality; D010051:Ovarian Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000401:mortality; D011379:Prognosis; D034622:RNA Interference; D012333:RNA, Messenger / Q000378:metabolism*; D034741:RNA, Small Interfering; D020133:Reverse Transcriptase Polymerase Chain Reaction; D043244:Ribonuclease III / Q000235:genetics / Q000378:metabolism*; D014162:Transfection; D016896:Treatment Outcome
chemical_list: D035683:MicroRNAs; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D004722:Endoribonucleases; C408087:DICER1 protein, human; C517918:DROSHA protein, human; D043244:Ribonuclease III; D053487:DEAD-box RNA Helicases