Dependence of NF-κB activation and free radical generation on silica-induced TNF-α production in macrophages

Yon Rojanasakul, Jiangping Ye, Fei Chen, Liying Wang, Ningli Cheng, Vincent Castranova, Val Vallyathan, Xianglin Shi

Research output: Contribution to journalArticlepeer-review

57 Scopus citations


Tumor necrosis factor α (TNFα) plays an important role in the pathogenesis of silicosis and other chronic inflammatory lung diseases. The present study investigates the role nuclear transcription factor κB (NF-κB) and oxygen free radicals in silica-induced TNFα production in primary alveolar macrophages and RAW 264.7 cells. Using electrophoretic mobility shift assay (EMSA) and enzyme-linked immunoadsorbent assay (ELISA), we have demonstrated that silica can induce NF-κB activation and TNFα expression in a dose-dependent manner. Transient transfection assays with a plasmid construct containing NF-κB binding sites linked to a reporter gene further show that silica is able to induce the transcriptional activation of NF-κB-dependent gene. Inhibition of NF-κB activation by SN50, a specific NF-κB blocker, abolishes silica-induced TNFα production. Pretreatment of the cells with catalase (H2O2 scavenger) or deferoxamine (·OH scavenger) effectively inhibits NF-κB and TNFα activation, whereas superoxide dismutase (O2 scavenger) has an opposite effect. These results indicate that silica mediated free radical generation and NF-κB activation play important roles in silica-induced TNFα gene expression.

Original languageEnglish
Pages (from-to)119-125
Number of pages7
JournalMolecular and Cellular Biochemistry
Issue number1-2
StatePublished - 1999

Bibliographical note

Funding Information:
This work was supported in part by the National Institutes of Health Grant HL54291 and by the National Institute of Occupational Safety and Health.


  • NF-κB
  • Oxygen radicals
  • Silica
  • TNFα
  • Transcription factors

ASJC Scopus subject areas

  • Molecular Biology
  • Clinical Biochemistry
  • Cell Biology


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