BMP-6 inhibits microRNA-21 expression in breast cancer through repressing deltaEF1 and AP-1

Cell Res. 2009 Apr;19(4):487-96. doi: 10.1038/cr.2009.34.


MicroRNAs (miRNAs), which are small noncoding RNA molecules, play important roles in the post-transcriptional regulation process. The microRNA-21 gene (miR-21) has been reported to be highly expressed in various solid tumors, including breast cancer. Bone morphogenetic protein-6 (BMP-6) has been identified as an inhibitor of breast cancer epithelial-mesenchymal transition (EMT) through rescuing E-cadherin expression. We initiated experiments to identify the relationships between miR-21 and BMP-6 in breast cancer progression. Real-time PCR analysis showed that miR-21 expression was very high in MDA-MB-231 cells that expressed little BMP-6. A reverse correlation between BMP-6 and miR-21 was also determined in breast cancer tissue samples. Moreover, BMP-6 inhibited miR-21 transcription in MDA-MB-231 cells. In order to investigate how BMP-6 inhibited the miR-21 promoter (miPPR-21), we constructed a series of miPPR-21 reporters. Luciferase assay results indicated that BMP-6 inhibited miPPR-21 activity through the E2-box and AP-1-binding sites. We also demonstrated that both deltaEF1 and TPA induced miR-21 expression. Using site-directed mutation and CHIP assay, we found that deltaEF1 induced miPPR-21 activity by binding to the E2-box on miPPR-21. Moreover, TPA triggered miPPR-21 activity through the AP-1 binding sites. BMP-6 treatment significantly reduced the binding of these factors to miPPR-21 by decreasing the expression of deltaEF1 and c-Fos/c-Jun. We also demonstrated that BMP-6-induced downregulation of miR-21 modified the activity of PDCD4 3'UTR and inhibited MDA-MB-231 cell invasion. deltaEF1 overexpression and TPA induction blocked this inhibitory effect of BMP-6. In conclusion, BMP-6-induced inhibition of miR-21 suggests that BMP-6 may function as an anti-metastasis factor by a mechanism involving transcriptional repression of miR-21 in breast cancer.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis Regulatory Proteins / metabolism
  • Bone Morphogenetic Protein 6 / metabolism*
  • Bone Morphogenetic Protein 6 / pharmacology
  • Breast Neoplasms / genetics*
  • Breast Neoplasms / metabolism
  • Breast Neoplasms / pathology
  • Cadherins / metabolism
  • Cell Line, Tumor
  • Down-Regulation
  • Homeodomain Proteins / antagonists & inhibitors*
  • Homeodomain Proteins / metabolism
  • Humans
  • MicroRNAs / genetics
  • MicroRNAs / metabolism*
  • MicroRNAs / pharmacology
  • Mutagenesis, Site-Directed
  • RNA, Small Interfering / metabolism
  • RNA-Binding Proteins / metabolism
  • Tetradecanoylphorbol Acetate / chemistry
  • Tetradecanoylphorbol Acetate / pharmacology
  • Transcription Factor AP-1 / antagonists & inhibitors*
  • Transcription Factor AP-1 / metabolism
  • Transcription Factors / antagonists & inhibitors*
  • Transcription Factors / metabolism
  • Transfection
  • Zinc Finger E-box-Binding Homeobox 1


  • Apoptosis Regulatory Proteins
  • Bone Morphogenetic Protein 6
  • Cadherins
  • Homeodomain Proteins
  • MIRN21 microRNA, human
  • MicroRNAs
  • PDCD4 protein, human
  • RNA, Small Interfering
  • RNA-Binding Proteins
  • Transcription Factor AP-1
  • Transcription Factors
  • ZEB1 protein, human
  • Zinc Finger E-box-Binding Homeobox 1
  • Tetradecanoylphorbol Acetate