Effect of curcumin on the proliferation of and apoptosis in HaCaT cells induced by tumor necrosis factor α

Objective To evaluate the effect of curcumin on the proliferation of and apoptosis in HaCaT cells induced by tumor necrosis factor α (TNF-α).Methods HaCaT cells were cultured with the presence of different concentrations (0,1,5,10,25,50,100 ng/ml) of recombinant TNF-α,curcumin of 20 μmol/L,or the combination of recombinant TNF-α (25 ng/ml) and curcumin (20 μmol/L),for 24 hours followed by the determination of cell proliferation with methyl thiazolyl tetrazolium (MTT) assay.Western blot was conducted to measure the protein expression of proliferating cell nuclear antigen (PCNA) and Notch-1 in HaCaT cells treated with recombinant TNF-α (25 ng/ml) and curcumin (20 μ mol/L) alone or in combination for 24 hours.Flow cytometry using annexin-V/propidium iodine (PI) was performed to assess the early apoptosis in HaCaT cells incubated with recombinant TNF-α of 25 ng/ml and curcumin of 20 μmol/L alone or in combination for 12 hours.Statistical analysis was carried out with one-way analysis of variance.Results Recombinant TNF-α promoted the proliferation of HaCaT cells in a dose-dependent manner,with the maximum proliferation activity observed in HaCaT cells treated with TNF-α of 25 ng/ml,while curcumin of 20 μmol/L effectively inhibited the proliferation of HaCaT cells induced by TNF-α of 25 ng/ml (P ＜ 0.01).TNF-α of 25 ng/ml had no obvious effect on cell apoptosis,while curcumin of 20 μ mol/L markedly induced the apoptosis in HaCaT cells,and there was a synergy between TNF-α of 25 ng/ml and curcumin of 20 μmol/L in the induction of apoptosis in HaCaT cells,with the apoptosis rate being 2.3％,3.4％,11.6％ and 16.8％ respectively in untreated cells,cells treated with TNF-α,curcumin,and the combination of TNF-α and curcumin,respectively.Conclusions Curcumin could enhance the inductive effect of TNF-α on the apoptosis in,but suppress the promotive effect of TNF-α on the proliferation of,HaCaT cells. Key words: Psoriasis; Tumor necrosis factor-alpha; Curcumin