Tetrandrine inhibits the proliferation and cytokine production induced by IL-22 in HaCaT cells

Objective To investigate the effect of tetrandrine (Tet) on HaCaT cell proliferation and cytokine expression induced by interleukin (IL)-22, and to investigate the underlying mechanism. Methods The half maximal inhibitory concentration (IC50) and antiproliferation effects of Tet on IL-22-treated HaCaT cells were analysed by MTT assay. Signal transducer and activator of transcription 3 (STAT3) expression was measured by reverse transcription plus real-time quantitative polymerase chain reaction (qPCR) and by Western blot. Phosphorylated (p)-STAT3 levels were also measured by Western blot. Cytokine production by HaCaT cells was analysed by enzyme-linked immunosorbent assay (ELISA) following administration of IL-22 and/or Tet. Results Tet displayed a dose-dependent inhibitory effect on HaCaT cell proliferation and reduced the phosphorylation level of STAT3 induced by IL-22, without affecting STAT3 mRNA and protein levels. Furthermore, co-incubation with Tet significantly down-regulated HaCaT cell production of tumour necrosis factor (TNF)-alpha, IL-1 beta, IL-6, IL-20 and chemokine (C-C motif) ligand 20 (CCL20) induced by IL-22. Conclusions Tet inhibits proliferation and cytokine production in HaCaT cells, and the process may involve the inhibition of STAT3 phosphorylation.