MicroRNA expression profiles associated with prognosis and therapeutic outcome in colon adenocarcinoma.
BACKGROUND
MicroRNAs have potential as diagnostic biomarkers and therapeutic targets in cancer. No study has evaluated the association between microRNA expression patterns and colon cancer prognosis or therapeutic outcome.


OBJECTIVE
To identify microRNA expression patterns associated with colon adenocarcinomas, prognosis, or therapeutic outcome.


METHODS
MicroRNA microarray expression profiling of tumors and paired nontumorous tissues was performed on a US test cohort of 84 patients with incident colon adenocarcinoma, recruited between 1993 and 2002. We evaluated associations with tumor status, TNM staging, survival prognosis, and response to adjuvant chemotherapy. Associations were validated in a second, independent Chinese cohort of 113 patients recruited between 1991 and 2000, using quantitative reverse transcription polymerase chain reaction assays. The final date of follow-up was December 31, 2005, for the Maryland cohort and August 16, 2004, for the Hong Kong cohort.


METHODS
MicroRNAs that were differentially expressed in tumors and microRNA expression patterns associated with survival using cancer-specific death as the end point. RESULTS Thirty-seven microRNAs were differentially expressed in tumors from the test cohort. Selected for validation were miR-20a, miR-21, miR-106a, miR-181b, and miR-203, and all 5 were enriched in tumors from the validation cohort (P < .001). Higher miR-21 expression was present in adenomas (P = .006) and in tumors with more advanced TNM staging (P < .001). In situ hybridization demonstrated miR-21 to be expressed at high levels in colonic carcinoma cells. The 5-year cancer-specific survival rate was 57.5% for the Maryland cohort and was 49.5% for the Hong Kong cohort. High miR-21 expression was associated with poor survival in both the training (hazard ratio, 2.5; 95% confidence interval, 1.2-5.2) and validation cohorts (hazard ratio, 2.4; 95% confidence interval, 1.4-3.9), independent of clinical covariates, including TNM staging, and was associated with a poor therapeutic outcome.


CONCLUSIONS
Expression patterns of microRNAs are systematically altered in colon adenocarcinomas. High miR-21 expression is associated with poor survival and poor therapeutic outcome.
Schetter
Aaron J
AJ
Laboratory of Human Carcinogenesis, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland 20892, USA.
Leung
Suet Yi
SY
Sohn
Jane J
JJ
Zanetti
Krista A
KA
Bowman
Elise D
ED
Yanaihara
Nozomu
N
Yuen
Siu Tsan
ST
Chan
Tsun Leung
TL
Kwong
Dora L W
DL
Au
Gordon K H
GK
Liu
Chang-Gong
CG
Calin
George A
GA
Croce
Carlo M
CM
Harris
Curtis C
CC
D000230:Adenocarcinoma / Q000188:drug therapy / Q000235:genetics* / Q000401:mortality / Q000473:pathology; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor; D017024:Chemotherapy, Adjuvant; D003110:Colonic Neoplasms / Q000188:drug therapy / Q000235:genetics* / Q000401:mortality / Q000473:pathology; D005260:Female; D020869:Gene Expression Profiling; D006801:Humans; D017403:In Situ Hybridization; D008297:Male; D035683:MicroRNAs / Q000032:analysis*; D008875:Middle Aged; D020411:Oligonucleotide Array Sequence Analysis; D011379:Prognosis; D012334:RNA, Neoplasm / Q000032:analysis*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D016019:Survival Analysis
D014408:Biomarkers, Tumor; C524940:MIRN21 microRNA, human; D035683:MicroRNAs; D012334:RNA, Neoplasm