title: Overexpression of Dicer predicts poor survival in colorectal cancer.
abstract: OBJECTIVE
  The RNASE III endonuclease Dicer is one of the key enzymes of microRNA biogenesis. The influence of Dicer-expression in tumour cells on the prognosis of patients with several cancers has been studied with controversial results among different cancer types. To date no one has examined the effect of this biomarker on survival in colorectal carcinoma. Thus, we aimed to study the influence of Dicer expression on survival in colorectal cancer.
  
  
  METHODS
  We performed immunohistochemical analyses on formalin-fixed paraffin embedded (FFPE) cancer tissue with an antibody against the Dicer protein. Tumour material from 237 cases was available from patients with colorectal adeonocarcinomas with moderate differentiation (G2) and without evidence of lymph-node (N0) or distant metastasis (M0). Sixty-four cases were in T2 and 173 in T3 stages. A tissue microarray (TMA) was constructed with each tumour in triplicate. Each tumour was assigned to a scoring scale of 0-3, depending on the cytoplasmatic expression of Dicer. A Kaplan-Maier analysis was performed and the log-rank test was used for significance levels by using SPSS v.17 software.
  
  
  RESULTS
  The expression of Dicer in colorectal carcinoma shows a strong association with poor survival (cancer specific survival=CSS, p<0,001) as well as with reduced progression free survival (PFS, p<0,001). In the group with no Dicer staining there was no recorded relapse (0/15) compared with 10/18 relapses in the group with the strongest staining of Dicer.
  
  
  CONCLUSIONS
  Strong expression of the central microRNA biosynthesis enzyme Dicer predicts poor prognosis in patients with colorectal cancer. This is in line with investigations on prostate cancer. Contradictory, in breast, lung and ovary cancer Dicer has been shown to be a marker of good prognosis. Further studies on the cellular functions of Dicer need to address these issues.
authors.affiliation: Institute of Pathology, University of Munich, Germany. c.faber@lmu.de
authors.forename: C
authors.initials: C
authors.lastname: Faber
authors.forename: D
authors.initials: D
authors.lastname: Horst
authors.forename: F
authors.initials: F
authors.lastname: Hlubek
authors.forename: T
authors.initials: T
authors.lastname: Kirchner
mesh_terms: D000368:Aged; D014408:Biomarkers, Tumor / Q000378:metabolism; D002454:Cell Differentiation; D015179:Colorectal Neoplasms / Q000235:genetics* / Q000401:mortality*; D003593:Cytoplasm / Q000378:metabolism; D053487:DEAD-box RNA Helicases / Q000096:biosynthesis* / Q000502:physiology*; D018572:Disease-Free Survival; D005260:Female; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D007150:Immunohistochemistry / Q000379:methods; D008207:Lymphatic Metastasis; D008297:Male; D035683:MicroRNAs / Q000378:metabolism; D008875:Middle Aged; D011379:Prognosis; D043244:Ribonuclease III / Q000096:biosynthesis* / Q000502:physiology*; D016896:Treatment Outcome
chemical_list: D014408:Biomarkers, Tumor; D035683:MicroRNAs; C408087:DICER1 protein, human; D043244:Ribonuclease III; D053487:DEAD-box RNA Helicases