Establishment of twist-1 and TGFBR2 as direct targets of microRNA-20a in mesenchymal to epithelial transition of breast cancer cell-line MDA-MB-231

Exp Cell Res. 2017 Dec 1;361(1):85-92. doi: 10.1016/j.yexcr.2017.10.005. Epub 2017 Oct 5.

Abstract

Messenchymal to epithelial transition (MET) is a significant physiological phenomenon involved in embryogenesis and cancer. This study aims at investigating the mechanism of microRNA-20a (miR-20a) mediated regulation of mesenchymal to epithelial transition and identification of its direct target genes in breast cancer cell-line, MDA-MB-231. Reduced migratory and invasive property, altered cellular morphology along with reduced capability for attachment to basement membrane was acquired by over-expression of miR-20a in invasive MDA-MB-231 cell-line initially expressing low level of this micro-RNA, indicating direct correlation between abundance of miR-20a and metastatic property. The switch from mesenchymal to epithelial cells mediated by miR-20a involved post-transcriptional down-regulation of twist1, which in turn controls downstream epithelial markers like E-cadherin, claudin and mesenchymal markers like N-cadherin, fibronectin, the crucial players of mesenchymal to epithelial transition (MET). Furthermore, another key component, TGF-β and one of its receptors (TGFBR2) were found to be down-regulated by miR-20a. Additionally, reporter assay established that post-transcriptional down-regulation of TGFBR2 occurred through direct binding of miR-20a to its 3'UTR, thus abrogating the TGF-β signaling pathway resulting in inhibition of MET. Delineating the underlying molecular mechanism of miR-20a-mediated MET and defining the target genes will help us to introduce a miRNA-mediated effective therapeutic strategy against breast cancer.

Keywords: Breast cancer; Cell-invasion; Cell-migration; Mesenchymal to Epithelial Transition (MET); Twist-1; miR‐20a.

MeSH terms

  • Antigens, CD
  • Apoptosis
  • Breast Neoplasms / genetics
  • Breast Neoplasms / metabolism
  • Breast Neoplasms / pathology*
  • Cadherins / genetics
  • Cadherins / metabolism
  • Cell Adhesion
  • Cell Movement
  • Cell Proliferation
  • Epithelial-Mesenchymal Transition*
  • Female
  • Gene Expression Regulation, Neoplastic*
  • Humans
  • MicroRNAs / genetics*
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism*
  • Protein Serine-Threonine Kinases / genetics
  • Protein Serine-Threonine Kinases / metabolism*
  • Receptor, Transforming Growth Factor-beta Type II
  • Receptors, Transforming Growth Factor beta / genetics
  • Receptors, Transforming Growth Factor beta / metabolism*
  • Tumor Cells, Cultured
  • Twist-Related Protein 1 / genetics
  • Twist-Related Protein 1 / metabolism*

Substances

  • Antigens, CD
  • CDH1 protein, human
  • Cadherins
  • MIRN20a microRNA, human
  • MicroRNAs
  • Nuclear Proteins
  • Receptors, Transforming Growth Factor beta
  • TWIST1 protein, human
  • Twist-Related Protein 1
  • Protein Serine-Threonine Kinases
  • Receptor, Transforming Growth Factor-beta Type II