High levels of microRNA-21 in the stroma of colorectal cancers predict short disease-free survival in stage II colon cancer patients.
Approximately 25% of all patients with stage II colorectal cancer will experience recurrent disease and subsequently die within 5 years. MicroRNA-21 (miR-21) is upregulated in several cancer types and has been associated with survival in colon cancer. In the present study we developed a robust in situ hybridization assay using high-affinity Locked Nucleic Acid (LNA) probes that specifically detect miR-21 in formalin-fixed paraffin embedded (FFPE) tissue samples. The expression of miR-21 was analyzed by in situ hybridization on 130 stage II colon and 67 stage II rectal cancer specimens. The miR-21 signal was revealed as a blue chromogenic reaction, predominantly observed in fibroblast-like cells located in the stromal compartment of the tumors. The expression levels were measured using image analysis. The miR-21 signal was determined as the total blue area (TB), or the area fraction relative to the nuclear density (TBR) obtained using a red nuclear stain. High TBR (and TB) estimates of miR-21 expression correlated significantly with shorter disease-free survival (p = 0.004, HR = 1.28, 95% CI: 1.06-1.55) in the stage II colon cancer patient group, whereas no significant correlation with disease-free survival was observed in the stage II rectal cancer group. In multivariate analysis both TB and TBR estimates were independent of other clinical parameters (age, gender, total leukocyte count, K-RAS mutational status and MSI). We conclude that miR-21 is primarily a stromal microRNA, which when measured by image analysis identifies a subgroup of stage II colon cancer patients with short disease-free survival.
Exiqon A/S, Diagnostic Product Development, Skelstedet 16, 2950 Vedbaek, Denmark. bosn@exiqon.com
Boye Schnack
BS
Nielsen
Stine
S
Jørgensen
Jacob Ulrik
JU
Fog
Rolf
R
Søkilde
Ib Jarle
IJ
Christensen
Ulla
U
Hansen
Nils
N
Brünner
Adam
A
Baker
Søren
S
Møller
Hans Jørgen
HJ
Nielsen
D000368:Aged; D000369:Aged, 80 and over; D015179:Colorectal Neoplasms / Q000378:metabolism* / Q000473:pathology*; D015342:DNA Probes / Q000737:chemistry; D018572:Disease-Free Survival; D005260:Female; D006801:Humans; D017404:In Situ Hybridization, Fluorescence; D008297:Male; D035683:MicroRNAs / Q000235:genetics / Q000378:metabolism*; D015999:Multivariate Analysis; D009367:Neoplasm Staging; D009841:Oligonucleotides / Q000737:chemistry; D011237:Predictive Value of Tests; D011379:Prognosis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D012680:Sensitivity and Specificity; D017154:Stromal Cells / Q000378:metabolism*; D013997:Time Factors
D015342:DNA Probes; C524940:MIRN21 microRNA, human; D035683:MicroRNAs; D009841:Oligonucleotides; C477371:locked nucleic acid