Shikonin Promotes Skin Cell Proliferation and Inhibits Nuclear Factor-κB Translocation via Proteasome Inhibition In Vitro

Abstract

Background:Shikonin is a major active chemical component extracted from Lithospermi Radix, an effective traditional herb in various types of wound healing. Shikonin can accelerate granulomatous tissue formation by the rat cotton pellet method and induce neovascularization in granulomatous tissue. The purpose of the study was to investigate its mechanism of action in human skin cells.Methods:MTS assay was used to measure cell growth. The collagen type I (COL1) mRNA expression and procollagen type I C-peptide (PIP) production were detected by real-time quantitative reverse transcription-polymerase chain reaction and enzyme-linked immunosorbent assay, respectively. Immunofluorescence and western blot analyses were carried out to investigate nuclear factor-κB (NF-κB) signaling pathway. Cell-based proteasome activity assay was used to determine proteasome activity.Results:In this study, we found that 10 μmol/L shikonin stimulated the growth of normal human keratinocytes and 1 μmol/L shikonin promoted growth of human dermal fibroblasts. However, shikonin did not directly induce COL1 mRNA expression and PIP production in dermal fibroblasts in vitro. In addition, 1 μmol/L shikonin inhibited translocation of NF-κB p65 from cytoplasm to nucleus induced by tumor necrosis factor-α stimulation in dermal fibroblasts. Furthermore, shikonin inhibited chymotrypsin-like activity of proteasome and was associated with accumulation of phosphorylated inhibitor κB-α in dermal fibroblasts.Conclusions:These results suggested that shikonin may promote wound healing via its cell growth promoting activity and suppress skin inflammation via inhibitory activity on proteasome. Thus, shikonin may be a potential therapeutic reagent both in wound healing and inflammatory skin diseases.

Shikonin Suppresses Lymphangiogenesis <i>via</i> NF-κB/HIF-1α Axis Inhibition

“…13,14,16,24) Shikonin has been found to suppress NF-κB function by inhibiting nuclear translocation and DNA binding activity of NF-κB p65 subunit in several cell types. [13][14][15][16] Shikonin was found to inhibit NF-κB activation and its nuclear translocation during lymphatic endothelial cord formation. Inhibition of NF-κB function by shikonin may affect expression of the lymphangiogenesis-related genes, leading to decrease in cord formation ability of lymphatic HIF-1 is an oxygen-regulated transcription factor composed of two subunits, HIF-1α and HIF-1β.…”

“…12) Several mechanisms have been reported for shikonin action in suppressing activation, nuclear translocation, and DNA binding activity of NF-κB. [13][14][15][16] However, the effect of shikonin on NF-κB function during lymphangiogenesis is still not known.…”

Biosynthesis and molecular actions of specialized 1,4-naphthoquinone natural products produced by horticultural plants

“… 236 The underlying mechanism of plumbagin and shikonin inhibition of NF-κB activation appears to entail suppression of an inhibitor of κBα (IκBα) phosphorylation and degradation, thus precluding the phosphorylation of the p65 subunit of NF-κB. 237–241 However, it is still unclear whether the inhibition of NF-κB activation by plumbagin, shikonin and 1,4-naphthoquinone (see ref. 226 ) is solely mediated via Keap1-dependent activation of Nrf2/ARE signaling or by other mechanisms, especially considering Keap1-independent mechanisms of regulating Nrf2 have been well documented 227 Furthermore, it is well established that 1,4-NQs are inhibitors of topoisomerases.…”

Therapeutic effects of shikonin on skin lesions in mouse models of allergic dermatitis and wound

“…Steroids delay wound healing by inhibiting angiogenesis and increase of collagen fiber, and suppressing mRNA expression of keratinocyte growth factor, which plays an important function in the morphogenesis of epithelium and wound re‐epithelialization at the wound site . In contrast, shikonin promotes wound healing in skin . Shikonin also stimulates the migration of intestinal epithelial cells through a transforming growth factor (TGF)‐β‐dependent process, which could promote the healing of an intestinal injury .…”