Phosphorylation of extracellular signal‐regulated kinase 1/2, p38 mitogen‐activated protein kinase and nuclear translocation of nuclear factor‐κB are involved in upregulation of matrix metalloproteinase‐9 by tumour necrosis factor‐α

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Upregulation of matrix metalloproteinase-9 (MMP-9) induced by tumour necrosis factor-alpha (TNF-alpha) is reportedly involved in a variety of non-neoplastic and neoplastic diseases. In this study, we examined which signalling pathways are involved in TNF-alpha-induced MMP-9 upregulation in cholangiocarcinoma (CC). We used two CC cell lines: HuCCT-1 and CCKS-1. In an ex vivo study using HuCCT-1 and CCKS-1 cells, TNF-alpha treatment induced MMP-9 production and activation via interaction with TNF receptor-1 (TNF-R1) but not with TNF receptor-2 (TNF-R2), shown by zymography, and increased MMP-9 promoter activity (luciferase assay). As for the signalling pathway, TNF-alpha stimulation led to the phosphorylation of extracellular signal-regulated kinase 1/2 (Erk1/2) and p38 mitogen-activated protein kinase (p38MAPK) and translocation of nuclear factor kappaB (NF-kappaB) (p65) into the nuclei. Inhibition studies using SB203580 (inhibitor of p38MAPK), U0126 (inhibitor of mitogen-activated or extracellular signal-regulated protein kinase 1/2) and MG132 (inhibitor of NF-kappaB) showed that the phosphorylation of Erk1/2 and p38MAPK with activation of NF-kappaB was closely related to MMP-9 upregulation in both cell lines. These data suggest that TNF-alpha/TNF-R1 interaction leads to the phosphorylation of Erk1/2 and p38MAPK and nuclear translocation of NF-kappaB, which is closely associated with the production and activation of MMP-9 in cultured CC cells of HuCTT-1 and CCKS-1. Upregulation of MMP-9 with NF-kappaB activation may be involved in the tumour invasion of CC.