Lucidone Promotes the Cutaneous Wound Healing Process via Activation of the PI3K/AKT, Wnt/β-catenin and NF-κB Signaling Pathways

Lucidone, which comprises a naturally occurring cyclopentenedione, has been investigated for its in vitro and in vivo wound healing properties, and the underlying molecular signaling cascades in the wound healing mechanism have been elucidated. We demonstrated the cell −/dose-specific responses of lucidone (0.5-8 μM) on proliferation and migration/invasion of keratinocyte HaCaT and fibroblast Hs68 cells. In keratinocytes, lucidone-induced nuclear translocation of β-catenin was accompanied by increased transcriptional target genes, including c-Myc and cyclin-D1, through GSK3β-dependent pathway. Correspondingly, lucidone promoted the cell-cycle by increasing PCNA/CDK4 and decreasing p21/p27 expressions. Lucidone induced EMT through the downregulation of epithelial (E-cadherin/occludin) and upregulation of mesenchymal (vimentin/Twist/Snail) marker proteins. Activated MMP-9/− 2 and uPA/uPAR as well as suppressed TIMP-1/− 2 and PAI-1 expressions by lucidone may promote the migration/invasion of keratinocytes. Notably, lucidone activated NF-κB signaling via IKK-mediated-IκB degradation, and its inhibition abolished MMP-9 activation and keratinocyte migration. Inhibition of PI3K/AKT signaling impaired the lucidone-induced proliferation/migration with corresponding suppression of β-catenin/c-Myc/cyclin-D1 and NF-κB/MMP-9 expressions. Results indicate that lucidone-induced PI3K/AKT signaling anchored the β-catenin/NF-κB-mediated healing mechanism. β-catenin knockdown substantially diminished lucidone-induced keratinocyte migration. Furthermore, lucidone increased endothelial cell proliferation/migration and triggered angiogenesis (MMP-9/uPA/ICAM-1). In macrophages, lucidone-activated NF-κB-mediated inflammation (COX-2/iNOS/NO) and VEGF, which may contribute to the growth of keratinocytes/fibroblasts and endothelial cells. Punched wounds on mice were rapidly healed with the topical application of lucidone (5 mM) compared with control ointment-treated mice. Taken together, lucidone accelerates wound healing through the cooperation of keratinocyte/fibroblast/endothelial cell growth and migration and macrophage inflammation via PI3K/AKT, Wnt/β-catenin and NF-κB signaling cascade activation.