IL-1β-mediated up-regulation of DEC1 in human gingiva cells via the Akt pathway

Growing evidence indicates that inflammation is a contributing factor leading to cancer development. However, pathways involved in this progression are not well understood. The involvement of DEC1 in cancer prompted us to examine whether pro-inflammatory cytokine interleukin-1β (IL-1β) induces the expression of DEC1 in oral inflammation. We found that IL-1β up-regulated DEC1 and hypoxia-inducible factor-1α (HIF-1α) protein and elevated the HIF-1α-responsive gene vascular endothelial growth factor (VEGF) expression in human primary gingival cells. HIF-1α and DEC1 immunoreactivity were significantly higher in the cases of gingival inflammation. We demonstrate that IL-1β up-regulates DEC1 and HIF-1α protein through a classical inflammatory signaling pathway involving Akt. Our data strongly suggest that PI-3K-Akt is an upstream participant in IL-1β-mediated DEC1 and HIF-1α induction. This is supported by the following data: (1) IL-1β induces 473 serine phosphorylation of Akt; (2) IL-1β-mediated Akt activation occurs in a PI-3K-dependent manner, and specific inhibition of PI-3K prevents Akt phosphorylation; and (3) inhibition of Akt prevents IL-1β-mediated DEC1 and HIF-1α induction. Taken together, these results suggest that DEC1 is one of the important transcription factors in inflammation.