Inhibition of constitutively active Stat3 suppresses growth of human ovarian and breast cancer cells

Oncogene. 2001 Nov 29;20(55):7925-34. doi: 10.1038/sj.onc.1204990.


Signal transducers and activators of transcription (STATs) are transcription factors activated in response to cytokines and growth factors. Constitutively active Stat3 has been shown to mediate oncogenic transformation in cultured cells and induce tumor formation in mice. An increasing number of tumor-derived cell lines as well as samples from human cancer have been reported to express constitutively active Stat3 protein. We previously demonstrated that ovarian cancer cell lines express high levels of constitutively active Stat3. In this study, we show that inhibition of the Stat3 signaling pathway using the Janus Kinase-selective inhibitor, AG490, and a dominant negative Stat3 (Stat3beta) significantly suppresses the growth of ovarian and breast cancer cell lines harboring constitutively active Stat3. In the ovarian cancer cell lines, AG490 also diminished the phosphorylation of Stat3, Stat3 DNA binding activity, and the expression of Bcl-x(L). Further, AG490 induced significant apoptosis in ovarian and breast cancer cell lines expressing high levels of constitutively active Stat3 but had a less profound effect on normal cells lacking constitutively active Stat3. AG490 also enhanced apoptosis induced by cisplatin in ovarian cancer cells. These results suggest that inhibition of Stat3 signaling may provide a potential therapeutic approach for treating ovarian and breast cancers.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis* / drug effects
  • Blotting, Western
  • Breast Neoplasms / genetics
  • Breast Neoplasms / metabolism
  • Breast Neoplasms / pathology*
  • Cell Division / drug effects
  • Cell Line
  • Cell Size / drug effects
  • Cisplatin / pharmacology
  • DNA-Binding Proteins / antagonists & inhibitors*
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism
  • Electrophoretic Mobility Shift Assay
  • Epithelial Cells / metabolism
  • Epithelial Cells / pathology
  • Female
  • Fibroblasts / metabolism
  • Fibroblasts / pathology
  • Genes, Dominant
  • Humans
  • Janus Kinase 3
  • Mutation / genetics
  • Ovarian Neoplasms / genetics
  • Ovarian Neoplasms / metabolism
  • Ovarian Neoplasms / pathology*
  • Phosphorylation / drug effects
  • Protein-Tyrosine Kinases / antagonists & inhibitors
  • Protein-Tyrosine Kinases / metabolism
  • Proto-Oncogene Proteins c-bcl-2 / metabolism
  • STAT3 Transcription Factor
  • Signal Transduction / drug effects
  • Time Factors
  • Trans-Activators / antagonists & inhibitors*
  • Trans-Activators / genetics
  • Trans-Activators / metabolism
  • Transfection
  • Tumor Cells, Cultured
  • Tyrphostins / pharmacology
  • bcl-X Protein


  • BCL2L1 protein, human
  • DNA-Binding Proteins
  • Proto-Oncogene Proteins c-bcl-2
  • STAT3 Transcription Factor
  • STAT3 protein, human
  • Trans-Activators
  • Tyrphostins
  • alpha-cyano-(3,4-dihydroxy)-N-benzylcinnamide
  • bcl-X Protein
  • Protein-Tyrosine Kinases
  • JAK3 protein, human
  • Janus Kinase 3
  • Cisplatin