Anti-microRNA-222 (anti-miR-222) and -181B suppress growth of tamoxifen-resistant xenografts in mouse by targeting TIMP3 protein and modulating mitogenic signal

J Biol Chem. 2011 Dec 9;286(49):42292-42302. doi: 10.1074/jbc.M111.270926. Epub 2011 Oct 18.


We have shown earlier that miR-221 and -222 are up-regulated in tamoxifen-resistant MCF-7 (OHT(R)) cells and Her2-positive human breast tumors when compared with Her2 negative tumors. In this study, we report markedly enhanced expression of miR-181b in OHT(R) cells and endocrine-resistant tumors. Further, anti-miR-222 or -181b in combination with tamoxifen suppressed growth of tamoxifen-resistant xenografts in mice. Luciferase reporter assay and expression analysis showed that TIMP3, a tissue metalloproteinase inhibitor, is a common target of miR-221/222 and -181b. In situ hybridization and immunohistochemical analysis demonstrated reciprocal relationships between TIMP3 and miR-221/222/181b expression in primary human breast carcinomas. Ectopic expression of TIMP3 inhibited growth of the OHT(R) cells, and its depletion in MCF-7 cells reduced sensitivity to tamoxifen in vitro and in vivo. EGF-induced MAPK and AKT phosphorylation were significantly higher in OHT(R) cells and miR-221/222-overexpressing MCF-7 cells than in control cells, which suggests modulation of mitogenic signaling by TIMP3 and the miRs. On the contrary, phosphoMAPK and phosphoAKT levels were diminished in TIMP3-overexpressing OHT(R) cells and increased in TIMP3-depleted MCF-7 cells. Low levels of estrogen or tamoxifen elicited similar differences in phosphoMAPK levels in these cells. Reduced levels of TIMP3 facilitated growth of tamoxifen-resistant cells by alleviating its inhibitory effect on ADAM10 and ADAM17, which are critical for OHT(R) cell growth. In conclusion, miR-221/222 and -181b facilitate growth factor signaling in tamoxifen-resistant breast cancer by down-regulating TIMP3, and corresponding anti-miRs can be used to render these tumors responsive to tamoxifen.

Publication types

  • Research Support, N.I.H., Extramural
  • Retracted Publication

MeSH terms

  • Animals
  • Antineoplastic Agents, Hormonal / pharmacology*
  • Breast Neoplasms / genetics
  • Breast Neoplasms / metabolism*
  • Cell Line, Tumor
  • Cell Movement
  • Cell Proliferation
  • Down-Regulation
  • Female
  • Gene Expression Regulation, Neoplastic*
  • Humans
  • Intercellular Signaling Peptides and Proteins / metabolism
  • Mammary Neoplasms, Animal / genetics
  • Mammary Neoplasms, Animal / metabolism*
  • Metalloproteases / metabolism
  • Mice
  • MicroRNAs / metabolism*
  • Neoplasm Transplantation
  • Tamoxifen / pharmacology*
  • Tissue Inhibitor of Metalloproteinase-3 / physiology*
  • Wound Healing


  • Antineoplastic Agents, Hormonal
  • Intercellular Signaling Peptides and Proteins
  • MIRN222 microRNA, human
  • MIRN222 microRNA, mouse
  • MIrn181 microRNA, human
  • MicroRNAs
  • Tissue Inhibitor of Metalloproteinase-3
  • mirn181 microRNA, mouse
  • Tamoxifen
  • Metalloproteases