Chemoprotective effects of curcumin in esophageal epithelial cells exposed to bile acids

Figure 1 Effect of curcumin concentration on cell viability and proliferation at concentration ≥ 100 μmol/L (A) and ≤ 10 μmol/L (B). HET-1A cells incubated in 96-well plates at a density of 10 000 cells/well for 24 h demonstrated decreased cell viability and proliferation in the presence of curcumin at a concentration ≥ 100 μmol/L or ≤ 10 μmol/L. The viability and proliferation were also reduced in the presence of curcumin combined with deoxycholic acid (DCA) when compared to vehicle control (2.5% ethanol). ^aP < 0.05 vs vehicle control. MTT: 3-(4,5-Dimethyl-2-thiazolyl)-2,5-diphenyl-2H-tetrazolium; BrdU: 5-bromo-2’-deoxyuridine; DCA: Deoxycholic acid.

Figure 2 Effect of curcumin and deoxycholic acid on cyclooxygenase-2 gene expression. A: Effect of curcumin on cyclooxygenase-2 (COX-2) gene expression. HET-1A cells in 6-well plates at a density of 1.5 × 10⁵ cells per well incubated with curcumin for 24 h showed unaltered gene expression of COX-2 when compared to vehicle control (0.2% ethanol). Error bars: mean ± SD (n = 4); B: Effect of both deoxycholic acid and curcumin on COX-2 gene expression. HET-1A cells in 6-well plates at a density of 1.5 × 10⁵ cells per well incubated with deoxycholic acid (DCA) for 24 h showed increased gene expression of COX-2 with increasing doses of DCA when compared to vehicle control (0.2% ethanol). The addition of curcumin diminished the increase in gene expression. Error bars: mean ± SD (n = 4).

Figure 3 Effect of curcumin and bile acid on superoxide dismutase gene expression. A: Effect of curcumin on superoxide dismutase (SOD)-1 and SOD-2 gene expression. HET-1A cells in 6-well plates at a density of 1.5 × 10⁵ cells per well incubated with curcumin for 24 h did not show a significant impact on SOD-1 or SOD-2 gene expression. Error bars: mean ± SD (n = 4); B: Effect of curcumin and bile acid on SOD-1 gene expression. HET-1A cells in 6-well plates at a density of 1.5 × 10⁵ cells per well incubated with deoxycholic acid (DCA) for 24 h showed a significant decrease in SOD-1 expression. When DCA treatment at 100 μmol/L was combined with curcumin the suppression in SOD-1 expression was alleviated. Error bars: mean ± SD (n = 4). ^aP < 0.05 vs vehicle control; C: Effect of curcumin and bile acid on SOD-2 gene expression. HET-1A cells in 6-well plates at a density of 1.5 × 10⁵ cells per well incubated with deoxycholic acid (DCA) for 24 h showed a significant increase in SOD-2 expression at a DCA concentration of 200 μmol/L. The combined treatment of DCA and curcumin showed reduced expression of SOD-2 at concentrations ≥ 50 μmol/L. Error bars: mean ± SD (n = 4).