Kirenol inhibits TNF-α-induced proliferation and migration of HaCaT cells by regulating NF-κB pathway

Psoriasis is a common chronic, inflammatory skin disease possessing properties of inflammatory cell infiltration and excessive proliferation of keratinocytes, the occurrence and development of which remain fully elucidated. Therefore, the study was designed to determine the effects of kirenol (50, 100 and 200 μg/mL) on Cultured Human Keratinocytes (cells) (HaCaT) in vitro and reveal its molecular mechanism. The in vitro psoriasis model was established utilizing tumor necrosis factor-α (TNF-α)-stimulated HaCaT cells. Kirenol, a diterpenoid compound, was applied at different concentrations (50, 100 and 200 μg/mL) to HaCaT cells for 24 h. The Cell Counting Kit-8 (CCK-8) and thymidine monobromodeoxyuridine (BrdU) assays were used to assess cell viability and proliferation, followed by assessment of cell migration by Transwell assay. Subsequently, inflammatory cytokines were measured by enzyme-linked immunosorbent assay (ELISA), and Western blot assay was used to evaluate expressions of p65, p-p65, IκBα and p-IκBα. Activities of superoxide dismutase (SOD), catalase (CAT), glutathione (GSH) and malondialdehyde (MDA) contents were measured spectrophotometrically. The results demonstrated that TNF-α induced a significant increase in cell viability and inflammatory cytokines, including expressions of Interleukin (IL)-6, IL-8, IL-22 and IL-1β in HaCaT cells, which was dose-dependently inhibited by kirenol. Similarly, TNF-α-induced cell migration was also suppressed by kirenol treatment. Furthermore, TNF-α stimuli induced the upregulation of phosphorylation levels of p65 and IκBα as well as p-p65–p65 and p-IκBα–IκBα ratios, whereas kirenol significantly suppressed the activation of cellular nuclear factor-kappa B (NF-κB) signaling pathway. In addition, kirenol significantly decreased the level of MDA but increased the levels of SOD, CAT and GSH in a dose-dependent manner. These results proposed that kirenol could inhibit the proliferation, migration, expression of inflammatory factors, and oxidative stress in HaCaT cells via suppressing NF-κB signaling pathway.