Quantitative measurement of serum microRNA-21 expression in relation to breast cancer metastasis in Chinese females

Ann Lab Med. 2015 Mar;35(2):226-32. doi: 10.3343/alm.2015.35.2.226. Epub 2015 Feb 12.


Background: Breast cancer is the most common type of cancer in females. Aberrant expression of microRNA-21 (miR-21) has previously been reported in breast cancer tissue. The aim of this study was to investigate expression levels of serum miR-21 in breast cancer patients and evaluate its prognostic value in Chinese females.

Methods: Real-time quantitative (RQ)-PCR was used to analyze miR-21 expression in archived serum, tumor tissue, and adjacent normal tissue from 549 participants (326 with breast cancer, 223 without breast cancer). We also analyzed associations between serum miR-21 expression and breast cancer subtypes and patient prognosis. Recurrence and survival were analyzed by using the multivariate Cox proportional hazards model.

Results: Expression of miR-21 was significantly higher in breast cancer tissues compared with normal adjacent breast tissues (P<0.001). The 2(-ΔΔCt) values for serum miR-21 in breast cancer patients versus healthy controls were 9.12±3.43 and 2.96±0.73, respectively. Multivariate Cox proportional hazards model suggested that serum miR-21 expression was an independent poor prognostic factor for both recurrence (hazard ratio [HR]= 2.942; 95% confidence interval [CI]=1.420-8.325; P=0.008) and disease-free survival (HR=2.732; 95% CI=1.038-7.273, P=0.003) in breast cancer.

Conclusions: Increased serum miR-21 expression level was correlated with poor prognosis of breast cancer patients, indicating that serum miR-21 may be a novel prognostic marker for recurrence and survival of breast cancer patients before resection.

Keywords: Biomarker; Breast cancer; Prognosis; Serum miR-21.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Biomarkers, Tumor / genetics
  • Breast / metabolism
  • Breast Neoplasms / metabolism
  • Breast Neoplasms / mortality
  • Breast Neoplasms / pathology*
  • Disease-Free Survival
  • Female
  • Humans
  • Kaplan-Meier Estimate
  • Lymphatic Metastasis
  • MicroRNAs / blood*
  • Neoplasm Recurrence, Local
  • Prognosis
  • Proportional Hazards Models
  • Real-Time Polymerase Chain Reaction


  • Biomarkers, Tumor
  • MIRN21 microRNA, human
  • MicroRNAs