TNF-α induces some proinflammatory cytokines including IL-1β, IL-6, IL-8, and itself by activation of NF-κB or MAPKs (p38, JNK, ERK). These cytokines play important roles in various inflammatory skin diseases, such as psoriasis. Recently it was also reported that expression of cyclin E is up-regulated by ERK pathway after TNF-α treatment. However, it was unknown whether curcumin, showing inhibitory effects on NF-κB and MAPKs, attenuates the expression of TNF-α-induced IL-1β, IL-6, IL-8, and TNF-α as well as cyclin E expression in HaCaT cells. In this study, we investigated the inhibitory effect of curcumin on expression of proinflammatory cytokines and cyclin E in TNF-α-treated HaCaT cells. We found that curcumin inhibited the expression of TNF-α-induced IL-1β, IL-6, and TNF-α, but not IL-8, in TNF-α-treated HaCaT cells as well as the TNF-α-induced cyclin E expression. In addition, curcumin inhibited the activation of MAPKs (JNK, p38 MAPK, and ERK) and NF-κB in TNF-α-treated HaCaT cells. Taken together, curcumin exerts anti-inflammatory and growth inhibitory effects in TNF-α-treated HaCaT cells through inhibition of NF-κB and MAPK pathways.

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