Prognostic value of Dicer expression in human breast cancers and association with the mesenchymal phenotype.
BACKGROUND
Dicer, a ribonuclease, is the key enzyme required for the biogenesis of microRNAs and small interfering RNAs and is essential for both mammalian development and cell differentiation. Recent evidence indicates that Dicer may also be involved in tumourigenesis. However, no studies have examined the clinical significance of Dicer at both the RNA and the protein levels in breast cancer.


METHODS
In this study, the biological and prognostic value of Dicer expression was assessed in breast cancer cell lines, breast cancer progression cellular models, and in two well-characterised sets of breast carcinoma samples obtained from patients with long-term follow-up using tissue microarrays and quantitative reverse transcription-PCR.


RESULTS
We have found that Dicer protein expression is significantly associated with hormone receptor status and cancer subtype in breast tumours (ER P=0.008; PR P=0.019; cancer subtype P=0.023, luminal A P=0.0174). Dicer mRNA expression appeared to have an independent prognostic impact in metastatic disease (hazard ratio=3.36, P=0.0032). In the breast cancer cell lines, lower Dicer expression was found in cells harbouring a mesenchymal phenotype and in metastatic bone derivatives of a breast cancer cell line. These findings suggest that the downregulation of Dicer expression may be related to the metastatic spread of tumours.


CONCLUSIONS
Assessment of Dicer expression may facilitate prediction of distant metastases for patients suffering from breast cancer.
Grelier
G
G
Université de Lyon, Université Lyon 1, ISPB, Lyon F-69003, France.
Voirin
N
N
Ay
A-S
AS
Cox
D G
DG
Chabaud
S
S
Treilleux
I
I
Léon-Goddard
S
S
Rimokh
R
R
Mikaelian
I
I
Venoux
C
C
Puisieux
A
A
Lasset
C
C
Moyret-Lalle
C
C
D014408:Biomarkers, Tumor / Q000032:analysis*; D015153:Blotting, Western; D001943:Breast Neoplasms / Q000378:metabolism* / Q000401:mortality / Q000473:pathology*; D045744:Cell Line, Tumor; D053487:DEAD-box RNA Helicases / Q000096:biosynthesis* / Q000235:genetics; D018572:Disease-Free Survival; D005260:Female; D020869:Gene Expression Profiling; D006801:Humans; D007150:Immunohistochemistry; D053208:Kaplan-Meier Estimate; D008648:Mesoderm / Q000473:pathology; D009361:Neoplasm Invasiveness / Q000235:genetics / Q000473:pathology; D009362:Neoplasm Metastasis / Q000235:genetics / Q000473:pathology; D010641:Phenotype; D011379:Prognosis; D012333:RNA, Messenger / Q000032:analysis; D034741:RNA, Small Interfering; D020133:Reverse Transcriptase Polymerase Chain Reaction; D043244:Ribonuclease III / Q000096:biosynthesis* / Q000235:genetics; D046888:Tissue Array Analysis; D014162:Transfection
D014408:Biomarkers, Tumor; D012333:RNA, Messenger; D034741:RNA, Small Interfering; C408087:DICER1 protein, human; D043244:Ribonuclease III; D053487:DEAD-box RNA Helicases