Differential expression of a chloride intracellular channel gene, CLIC4, in transforming growth factor-beta1-mediated conversion of fibroblasts to myofibroblasts

Am J Pathol. 2002 Aug;161(2):471-80. doi: 10.1016/s0002-9440(10)64203-4.


Conversion of fibroblasts into myofibroblasts as mediated by transforming growth factor-beta1 (TGF-beta1) is the most prominent stromal reaction to a number of epithelial lesions including breast cancer. To identify genes which are regulated during this process, the mRNA profiles from primary breast fibroblasts treated with or without TGF-beta1 were analyzed by differential display. Ninety-five differentially expressed transcripts were PCR-cloned and sequenced, and 28 clones were selected for verification in a hybridization array. By use of gene-specific sequence tags, nine differentially expressed genes were identified. One of the clones, identified as CLIC4, a member of the CLIC family of chloride channels, was up-regulated more than 16 times in myofibroblasts and was therefore chosen for further analysis. Using RT-PCR, comparison with CLIC1, CLIC2, CLIC3, and CLIC5 demonstrated that CLIC4 was unique by being up-regulated by TGF-beta1 in myofibroblasts. Immunohistochemistry showed a hitherto unknown, distinctive pattern of CLIC4 expression in breast stroma. Whereas normal breast fibroblasts were devoid of CLIC4 protein expression, myofibroblasts of breast carcinomas were strongly CLIC4-positive. The functional significance of CLIC4 was analyzed in MEF/3T3 fibroblasts by conditional expression using the tetracycline-repressive gene regulation system. In a migration assay, we found that CLIC4 inhibited cell motility by 27%. These results suggest that CLIC4 is differentially regulated in fibroblasts and that its expression contributes to a collective stationary myofibroblast phenotype.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Breast / cytology
  • Cell Differentiation / drug effects
  • Cell Differentiation / genetics
  • Cell Movement / genetics
  • Cells, Cultured
  • Chloride Channels / biosynthesis
  • Chloride Channels / genetics*
  • Female
  • Fibroblasts / cytology*
  • Fibroblasts / metabolism*
  • Gene Expression Regulation / drug effects
  • Humans
  • Transforming Growth Factor beta / pharmacology


  • CLIC4 protein, human
  • Chloride Channels
  • Transforming Growth Factor beta