Interleukin-1β potentiates transforming growth factor-β-induced fibronectin expression, migration, and invasiveness of mesenchymal-like SK-Hep1 cells via p38 mitogen-activated protein kinase-SMAD2/3 crosstalk.

BACKGROUND: Hepatocellular carcinoma (HCC) progression and metastasis are closely associated with the acquisition and maintenance of a mesenchymal phenotype. The transforming growth factor (TGF)-β/SMAD signaling pathway stabilizes the mesenchymal state of HCC, whereas the inflammatory cytokine interleukin-1β (IL-1β) is abundantly expressed in the HCC tumor microenvironment and activates p38 mitogen-activated protein kinase (MAPK), a key mediator of cell migration and invasion. However, the role of inflammatory cytokines in modulating TGF-β-mediated mesenchymal phenotypes remains unclear. Therefore, this study aimed to determine the function of IL-1β in the regulation of mesenchymal phenotypes in SK-Hep1 cells and elucidate the roles of the TGF-β/SMAD and p38 MAPK signaling pathways. MATERIALS AND METHODS: Cells were treated with TGF-β1, IL-1β, or both in combination and mesenchymal marker expression was assessed by western blotting and immunofluorescence. Cell migration and invasion were evaluated by wound healing and Matrigel transwell invasion assays. The selective p38 inhibitor SB202190 was used to determine pathway dependency. RESULTS: TGF-β1 induced fibronectin and N-cadherin expression and increased their migratory and invasive capacities, whereas IL-1β further enhanced these effects. Mechanistically, IL-1β markedly increased the p38 MAPK phosphorylation and enhanced the TGF-β1-mediated SMAD2/3 phosphorylation and nuclear trans-localization. Furthermore, SB202190 decreased fibronectin and N-cadherin expression and reduced the migratory and invasive capacities of SK-Hep1 cells. CONCLUSION: These results indicate that IL-1β enhances TGF-β1-mediated mesenchymal phenotypes in SK-Hep1 cells via the activation of a p38 MAPK pathway that is associated with TGF-β/SMAD signaling. Considering that inflammation accelerates HCC progression and metastasis by enhancing the mesenchymal phenotype, these findings support further investigation of anti-inflammatory strategies for HCC management.