Silencing of the transcription factor STAT3 sensitizes lung cancer cells to DNA damaging drugs, but not to TNFα- and NK cytotoxicity

Exp Cell Res. 2013 Feb 15;319(4):506-16. doi: 10.1016/j.yexcr.2012.11.005. Epub 2012 Nov 10.


Transcription factor STAT3 (Signal Transducers and Activators of Transcription 3) is persistently active in human tumors and may contribute to tumor progression. Inhibition of STAT3 expression/activity could be a good strategy to modulate tumor cell survival and responses to cancer chemotherapeutics or immune cytotoxicity. We silenced STAT3 expression in human A549 lung cancer cells to elucidate its role in cell survival and resistance to chemotherapeutics, TNFα and natural killer (NK)-mediated cytotoxicity. We demonstrate that STAT3 is not essential for basal survival and proliferation of A549 cancer cells. Stable silencing of STAT3 expression sensitized A549 cells to DNA damaging chemotherapeutics doxorubicin and cisplatin in a p53-independent manner. Sensitization to DNA damage-inducing chemotherapeutics could be due to down-regulation of the Bcl-xL expression in STAT3 depleted cells. In contrast, knockdown of STAT3 in cancer cells did not modulate responses to TNFα and NK-mediated cytotoxicity. We found that STAT3 depletion increased the NFκB activity likely providing the compensatory, pro-survival signal. The treatment with TNFα, but not doxorubicin, enhanced this effect. We conclude that STAT3 is not crucial for the control of basal cell proliferation and survival of lung carcinoma cells but modulates susceptibility to DNA damaging chemotherapeutics by regulation of intrinsic pro-survival pathways.

Publication types

  • Evaluation Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Antineoplastic Agents / administration & dosage*
  • Antineoplastic Agents / pharmacology
  • Carcinoma, Non-Small-Cell Lung / drug therapy
  • Carcinoma, Non-Small-Cell Lung / genetics
  • Carcinoma, Non-Small-Cell Lung / immunology
  • Carcinoma, Non-Small-Cell Lung / therapy*
  • Cell Proliferation / drug effects
  • Cell Survival / drug effects
  • Cell Survival / genetics
  • Cells, Cultured
  • Combined Modality Therapy
  • Cytotoxicity, Immunologic* / drug effects
  • Cytotoxicity, Immunologic* / physiology
  • DNA Damage / drug effects
  • Drug Synergism
  • Gene Expression Regulation, Neoplastic / drug effects
  • Humans
  • Immunotherapy, Adoptive
  • Killer Cells, Natural / immunology
  • Killer Cells, Natural / physiology*
  • Lung Neoplasms / drug therapy
  • Lung Neoplasms / genetics
  • Lung Neoplasms / immunology
  • Lung Neoplasms / therapy*
  • RNA Interference / drug effects
  • RNA Interference / physiology
  • RNA, Small Interfering / administration & dosage
  • RNA, Small Interfering / pharmacology*
  • STAT3 Transcription Factor / antagonists & inhibitors*
  • STAT3 Transcription Factor / genetics
  • Transcription Factors / antagonists & inhibitors
  • Transcription Factors / genetics
  • Tumor Necrosis Factor-alpha / administration & dosage
  • Tumor Necrosis Factor-alpha / pharmacology*


  • Antineoplastic Agents
  • RNA, Small Interfering
  • STAT3 Transcription Factor
  • STAT3 protein, human
  • Transcription Factors
  • Tumor Necrosis Factor-alpha