Figure 1.
Effects of SFN on the proliferation of normal and tumour cells.
When cells grew to 70–80% confluence, a range of doses of SFN (0–160 µM) were added to the cell culture medium for 24–48 h. The control cells were treated with DMSO (0.1%), and cell viability was determined by the MTT cell proliferation assay (CCD-1092SK cell viability was determined by WST-1 assay according to manufacturer's instructions [88]). Each data point represents the mean ± SD of at least 5 replicates. Statistical significance from the control, *p<0.05, or **p<0.01. A: results from bladder cancer T24, hepatoma HepG2, and colon cancer Caco-2 cells. B: Results from immortalised hepatocyte HHL-5, colon epithelial CCD841, and skin fibroblast CCD-1092SK cell lines.
Figure 2.
Effects of SFN and 3-MA on cell migration.
A: After starvation overnight, bladder cancer T24 cells were treated with SFN at the concentrations indicated for 24 h, cell migration was measured by a cell migration assay using the ThinCert cell culture inserts (Greiner Bio-One Ltd.). Each bar represents the mean ± SD of 3 replicates. B: Effect of pre-treatment of 3-MA on cell migration. DMSO (0.1% was used as a control). Statistical significance from the control, *p<0.05, or **p<0.01.
Figure 3.
Effect of SFN on translocation of Nrf2 into cell nucleus.
Nrf2 was detected in nuclear extracts from cells exposed to SFN (0, 2.5, 5 and 10 µM) for 24 h, using a Western blot assay. Control cells were treated with DMSO (0.1%). A: immortalised human hepatocyte HHL-5; B: human heptoma HepG2 cells.
Figure 4.
Effect of pre-treatment of cells with SFN protect against H2O2-induced cell death.
Cells were cultured in 96 well plates. When they reached 70–80% confluence, cells were pre-treated with SFN (5 µM) for 24 h (HHL-5, A) or 48 h (MCF-7, B). The cell culture medium was replaced with H2O2 at the concentrations indicated for a further 24 h. C: HHL-5 cell were pre-treated with SFN (2 µM) and Se (0.1 µM) for 24 h before exposure to H2O2 (400 µM) for a further 24 h. The cell viability was measured using MTT assay. Statistical significance from corresponding controls: *p<0.05; **p<0.01.
Figure 5.
Effect of SFN on endothelial tube formation in a 3-D angiogenesis assay.
Culture medium supplemented with SFN (0–40 µM) was added to the top of 3-D collagen gels and then changed every 24 h with fresh SFN added. 3-D gels were fixed at day 5, immunostained with CD31 (red) and collagen type IV (green), and counterstained with DAPI (blue). (A): Low magnification pictures were taken from five random fields of each sample and calculated for average tube length. (B) Representative pictures are shown in triple staining with higher magnification. Data are expressed as mean ± SD (n = 5) (C). *P<0.05; ** P<0.01 compared to untreated control.
Table 1.
Human studies with plasma levels of dietary ITCs.
Figure 6.
A schematic diagram on the hormetic effect of ITCs.
For all cell types, dosage range 0-A is safe. In the majority of diets, the intakes of hormetic phytochemicals are likely to fall within this safe range. For normal cells, dose B could be used promote new blood vessel formation or promote wound healing; doses >C are toxic. For tumour cells, doses between A and C should be avoided; and doses >C to D could be used for chemotherapy.