Significance of cysteine rich transcription factor (CRTF) in the synthesisof tissue inhibitor of metalloproteinases 1 (TIMP-1) in gastrointestinal cancers

We previously reported that a novel promoter enhancer element "human tissue inhibitors of metalloproteinases 1 (TIMP-1) enhancer" (HTE) and a novel tr ansacting protein "cysteine rich transcription factor" (CRTF) induced TIMP- 1 synthesis in prostate cancer cells 2xN.I.PC-3. In the present study, to c larify the significance of CRTF in gastrointestinal cancers we measured the binding activity of CRTF to HTE using an electrophoretic mobility shift as say (EMSA), and the TIMP-1 concentration by ELISA after various stimulation of six cancer cell lines (KE-3, TE-9, MKN-28, MKN-45, KM12SM, SW620). In t hree cell lines (KE-3, MKN-45, SW620), both the binding activity of CRTF an d TIMP-1 concentration significantly increased after IL-10 stimulation. Fet al bovine serum (FBS) did not affect the binding activity of CRTF, whereas FBS induced TIMP-1 synthesis in all cell lines. In KE-3 esophageal cancer c ells and SW620 colon cancer cells, both the binding activity of CRTF and TI MP-1 concentration increased in the presence of a conditioned medium (CM) o f fibroblasts which was isolated from human colon cancer tissues, but did n ot increase in MKN-45 cells. Moreover, in the fibroblasts, both the binding activity of CRTF and the TIMP-1 concentration increased in the presence of CM from KM12SM, SW620, and TE-9 cancer cell lines. These results suggested that IL-10, and unknown factors in addition to IL-1 0, induced TIMP-1 synthesis via an increase in the binding activity of CRTF in gastrointestinal cancers, and that interaction between cancer cells and fibroblasts may play an important role in TIMP-1 synthesis through a signa l transduction pathway consisting of CRTF phosphorylation and HTE activatio n.