Low levels of serum miR-99a is a predictor of poor prognosis in breast cancer

Genet Mol Res. 2016 Aug 26;15(3). doi: 10.4238/gmr.15038338.


MicroRNA (miRNA) deregulation has been previously linked to the initiation and development of breast cancer. Although miR-99a is aberrantly expressed in many types of cancers, including breast cancer, the serum miR-99a expression level in breast cancer and its clinical significance remains unknown. Blood samples were obtained from 72 patients with breast cancer and 40 healthy volunteers, and subjected to real-time polymerase chain reaction to evaluate the level of expression of serum miR-99a in the study participants. Furthermore, we investigated the association between serum miR-99a and the clinical outcome of breast cancer. Serum miR-99a expression was significantly downregulated in patients with breast cancer, compared to that in healthy controls (P < 0.01). Moreover, the serum miR-99a was correlated with various clinical parameters of breast cancer, including lymph node metastasis (P = 0.0194), distant metastasis (P = 0.0037), Ki67 intensity (P = 0.0164), TNM stage (P = 0.0096), and histological grade (P = 0.0051) of cancer. Additionally, breast cancer patients displaying lower miR-99a levels showed poorer overall survival rates (P = 0.0411). The serum miR-99a level was also found to be an independent risk factor for breast cancer (hazard ratio = 3.176, 95% confidence interval = 1.543-7.360, P = 0.023). Our data indicated that serum miR-99a expression was downregulated in breast cancer patients; moreover, this downregulation was associated with poor prognosis, suggesting that serum miR-99a could function as a tumor suppressor in breast cancer.

MeSH terms

  • Adult
  • Breast Neoplasms / blood
  • Breast Neoplasms / diagnosis*
  • Breast Neoplasms / genetics*
  • Breast Neoplasms / mortality
  • Case-Control Studies
  • Female
  • Gene Expression Regulation, Neoplastic*
  • Humans
  • Ki-67 Antigen / blood
  • Ki-67 Antigen / genetics
  • Lymphatic Metastasis
  • MicroRNAs / blood
  • MicroRNAs / genetics*
  • Middle Aged
  • Neoplasm Grading
  • Neoplasm Staging
  • Prognosis
  • Receptor, ErbB-2 / genetics
  • Receptor, ErbB-2 / metabolism
  • Receptors, Estrogen / genetics
  • Receptors, Estrogen / metabolism
  • Receptors, Progesterone / genetics
  • Receptors, Progesterone / metabolism
  • Risk Factors
  • Survival Analysis


  • Ki-67 Antigen
  • MIRN99 microRNA, human
  • MicroRNAs
  • Receptors, Estrogen
  • Receptors, Progesterone
  • ERBB2 protein, human
  • Receptor, ErbB-2