title: Circulating miR-17-3p, miR-29a, miR-92a and miR-135b in serum: Evidence against their usage as biomarkers in colorectal cancer.
abstract: BACKGROUND
  Colorectal cancer (CRC) is one of the leading causes of cancer-related death in the world. Therefore, there is a high demand for cost-effective and non-invasive biomarkers that would enable an early detection of asymptomatic and curable disease with high sensitivity and specificity.
  
  
  OBJECTIVE
  The main objective of this study was to investigate the potential of circulating miRNAs as biomarkers of CRC.
  
  
  METHODS
  Total RNA enriched for small RNAs was isolated from 100~sera of patients with CRC and 30 sera of healthy donors. The expression levels of miR-17-3p, miR-29a, miR-92a and miR-135b were determined using quantitative real-time PCR. The average expression levels of particular miRNAs were normalized to miR-16 levels and statistically evaluated.
  
  
  RESULTS
  Using Mann-Whitney U test, no significant differences were observed in miR-17-3p (P=0.18), miR-29a (P=0.14) and miR-92a (P=0.60) levels between sera of CRC patients and controls. The levels of miR-135b in serum were too low to be quantified accurately. Subsequently, we tried to correlate expression levels of analyzed miRNAs to clinical-pathological features of CRC patients. Only levels of mir-29a were correlated with the clinical stage (P=0.04). Expression levels of the other miRNAs were correlated neither with the clinical stage, nor with the grade.
  
  
  CONCLUSIONS
  Interestingly, our results are contradictory to previous studies performed on the CRC patients from Chinese population, providing an evidence against usage of serum miR-17-3p, miR-29a, miR-92a and miR-135b as new biomarkers for early detection of CRC.
authors.affiliation: Department of Comprehensive Cancer Care, Masaryk Memorial Cancer Institute, Brno, Czech Republic.
authors.forename: Petra
authors.initials: P
authors.lastname: Faltejskova
authors.forename: Ondrej
authors.initials: O
authors.lastname: Bocanek
authors.forename: Milana
authors.initials: M
authors.lastname: Sachlova
authors.forename: Marek
authors.initials: M
authors.lastname: Svoboda
authors.forename: Igor
authors.initials: I
authors.lastname: Kiss
authors.forename: Rostislav
authors.initials: R
authors.lastname: Vyzula
authors.forename: Ondrej
authors.initials: O
authors.lastname: Slaby
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D014408:Biomarkers, Tumor / Q000097:blood*; D016022:Case-Control Studies; D015179:Colorectal Neoplasms / Q000097:blood / Q000175:diagnosis*; D005260:Female; D006801:Humans; D008297:Male; D035683:MicroRNAs / Q000097:blood*; D008875:Middle Aged
chemical_list: D014408:Biomarkers, Tumor; C544965:MIRN135 microRNA, human; C524941:MIRN17 microRNA, human; C532045:MIRN29a microRNA, human; C541874:MIRN92 microRNA, human; D035683:MicroRNAs