Figure 4.

SSM increased the nuclear translocation of Nrf2 and induced the expressions of cytoprotective genes in Caco-2 cells. (a) The effect of SSM on the protein expressions of Nrf2 and its target genes was analyzed by western blot in Caco-2 cells treated with 0 μM SSM (0.1% DMSO) and various concentrations of SSM (10, 20, 40, and 80 μM) for 2 and 8 h. (b–g) Quantitative data were obtained from the densitometric quantification of immunoblots using ImageJ software. Data were expressed as the mean ± SD (n = 5). ^∗p < 0.05, ^∗∗p < 0.01, and ^∗∗∗p < 0.001 versus the DMSO treatment group. (h) Caco-2 cells were transfected with si-control or si-Nrf2 for 48 h. Then, the protein expressions of Nrf2 and its target genes were analyzed by western blot in these cells treated with 0.1% DMSO (-) or 40 μM SSM (+) for 8 h. Quantitative data were obtained from the densitometric quantification of immunoblots using ImageJ software. Data were expressed as the mean ± SD (n = 5). ^∗p < 0.05, ^∗∗p < 0.01, and ^∗∗∗p < 0.001 versus the DMSO treatment group. ^#p < 0.05 versus the SSM treatment group. (i) Caco-2 cells were transfected with si-control or si-Nrf2 for 48 h. Then, the cells were pretreated with 0 μM SSM (0.1% DMSO) or 40 μM SSM for 8 h and 1.6 mM H₂O₂ for another 24 hours. Cell viability was measured by MTT assay. Data were expressed as the mean ± SD (n = 5). ^∗p < 0.05, ^∗∗p < 0.01, and ^∗∗∗p < 0.001 versus the H₂O₂ treatment group. ^#p < 0.05, ^##p < 0.01, and ^###p < 0.001 versus the si-control group.