Deoxyshikonin inhibits growth and induces apoptosis of hypertrophic scar-derived fibroblasts by downregulating FBXO expression through autophagy.

Hypertrophic scar (HS) is a fibro-proliferative disorder of cutaneous wound healing, which seriously impacts the patient's quality of life. Deoxyshikonin (DSK) as a natural shikonin derivative possesses various pharmacological effects, however, whether DSK is involved in anti-fibrotic function for HS remain unclear. This study aimed to investigate the effect of DSK on HS-derived fibroblasts (HSFs) growth and reveal its possible mechanism. HSFs were isolated from human HS tissues. The viability and proliferation of HSFs under DSK treatment were evaluated by CCK-8 and EdU assays. The evaluation of the apoptotic ratio was performed using flow cytometry. The effects of DSK on FBXO2 expressions, apoptosis-associated proteins, autophagy-related proteins and the molecules involved in Mitogen-activated protein kinase (MAPK) family were evaluated by western blot and immunofluorescence staining. mRFP-GFP-LC3 overexpression adenovirus was employed to detect autophagosome formation. Co-immunoprecipitation (Co-IP) assays were performed to examined the interaction between p62 and FBXO2. DSK was found to inhibit the proliferation and induce apoptosis of HSFs. Furthermore, we found that DSK suppressed the expression of FBXO2, and FBXO2 overexpression alleviated the effect of DSK on proliferation and apoptosis of HSFs. DSK possessed capability to induce autophagy by which elevating FBXO2 degradation by p62 interaction. Inhibiting autophagy using Atg5 shRNA increased FBXO2 expression and decreased apoptotic protein expression under DSK stimulation. Mechanistically, DSK-induced autophagy mediated the down-regulation of FBXO2 by activating extracellular regulated kinase 1/2 (ERK1/2) signaling. In conclusion, our finding demonstrated that DSK inhibited proliferation and induced apoptosis of HSFs by autophagy-mediated degradation of FBXO2 via activating ERK1/2 signaling. DSK emerges as a promising strategy to enhance outcome of hypertrophic scar.