Rationally designed inhibitors identify STAT3 N-domain as a promising anticancer drug target

ACS Chem Biol. 2007 Dec 21;2(12):799-809. doi: 10.1021/cb700186x.


Activation of the signal transducer and activator of transcription 3 (STAT3) is frequently detected in many cancer types. Activated STAT3 may participate in oncogenesis by stimulating cell proliferation and resisting apoptosis, as well as promoting tumor angiogenesis, invasion, and migration. Many STAT3-dependent cellular responses are mediated through interactions with other proteins, and the amino-terminal domain (N-domain) of STAT3 was proposed to be responsible for this. Our NMR studies revealed that synthetic analogs of the STAT4 second alpha-helix bind to the N-domain and perturb its structure. Structural data available for the STAT4 N-domain was used for the rational design of STAT3 helix 2 analogs with enhanced biological activity. Cell-permeable derivatives of the STAT3 second helix were found to directly and specifically bind to STAT3 but not STAT1 as determined by FRET analysis in cells expressing GFP-STAT3 and GFP-STAT1. Furthermore, they potently induced apoptotic death in breast cancer cells but not normal breast cells or STAT3-deficient fibroblasts. The inhibitors caused significant changes in the mitochondrial potential of cancer cells, leading to cell death. These compounds not only are promising drug candidates but also offer a convenient tool for studying the mechanisms of action of STAT transcription factors and have facilitated our understanding of the crucial role of the N-domain in STAT3 function.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, N.I.H., Intramural

MeSH terms

  • Antineoplastic Agents / chemistry*
  • Antineoplastic Agents / toxicity*
  • Cell Survival / drug effects
  • Drug Design*
  • Models, Molecular
  • Nuclear Magnetic Resonance, Biomolecular
  • Protein Structure, Tertiary
  • STAT3 Transcription Factor / antagonists & inhibitors*
  • STAT3 Transcription Factor / chemistry
  • STAT3 Transcription Factor / genetics
  • STAT3 Transcription Factor / metabolism*


  • Antineoplastic Agents
  • STAT3 Transcription Factor