Curcumin inhibits oxidative stress-induced TRPM2 channel activation, calcium ion entry and apoptosis values in SH-SY5Y neuroblastoma cells: Involvement of transfection procedure

Figures & data

Figure 1. Effects of curcumin on TRPM2 channel activity in SH-SY5Y neuroblastoma cells. (A) Control record: original recordings from SH-SY5Y cells. (B) Non-transfected control group, was tested whether H₂O₂ cause on the cellular cationic currents or not. (C) Non-transfected but curcumin incubated records of cells were to test any relationship between curcumin incubation and H₂O₂ induction on the currents. (D) TRPM2 currents in the transfected SH-SY5Y cells were stimulated by H₂O₂ (10 mM) in the chamber (bath) solution and they were inhibited by ACA (25 μM) in the bath. (E) I–V curve of panel D: current-voltage relationships of whole-cell currents in the presence of various extracellular cations, activators and inhibitors as indicated (same experiments as in panel D). (F) TRPM2 currents inhibited by curcumin incubation in the transfected + curcumin group. The cells were incubated with curcumin (5 μM) after transfection for 24 h and then they were not gated by H₂O₂ administration (in the patch chamber). The holding potential was -60 mV. NMDG⁺ time is shown where the normal bath solution (140 nM Na⁺) was exchanged to a solution with NMDG⁺ as main cation (150 mM, Ca²⁺ free solution). W.C.: Whole cell.

Figure 2. Effects of curcumin on TRPM2 cation channel current densities in SH-SY5Y neuroblastoma cells. The cells were in vitro treated with H₂O₂ (10 mM) and ACA (25 μM). For each of the experiments, the initial current density (divided to the cell capacitance, which is a measure of cell size) was calculated after administration of H₂O₂ (mean ± SD). The numbers in parentheses indicate n number of groups. Significant stimulation and inhibition of currents were indicated with letters a; p < 0.001 vs control group, b; p < 0.001 vs curcumin group, c; p < 0.001 vs transfected group. Cur: curcumin; Trans: transfected; Trans + Cur: express transfected + curcumin group.

Figure 3. A. Calcium release from four groups of SH-SY5Y cells following stimulation with 25 μM cumene hydroperoxide (CHPx). Original time course chart recordings showing [Ca²⁺]i transients in SH-SY5Y cells. B. Bar charts showing mean ± SD data for [Ca²⁺]i from H₂O₂ stimulated groups of SH-SY5Y cells (n = 6 for each). Note that the significant elevation in [Ca²⁺]i for SH-SY5Y cells compared to control group. a; p < 0.05 vs control group, b; p < 0.05 vs transfected group. Cur: curcumin; Trans: transfected; Trans + Cur: express transfected + curcumin group.

Figure 4. Effects of TRPM2 transfection and/or curcumin incubation on the TRPM2 channel protein (A), PARP1 enzyme (B), procaspase 9 and procaspase 3 enzymes expression levels (C) relative densities represented of these protein levels respectively in SH-SY5Y cells. Cur: curcumin; Trans: transfected; Trans + Cur: express transfected + curcumin group.

Figure 5. Effects of curcumin administration on ROS production levels in SH-SY5Y cells (mean ± SD; n = 8). The values were expressed as fold increase over the control level (experimental/control). a; p < 0.001 vs control group, b; p < 0.001 vs curcumin group, c; p < 0.001 vs transfected group. Cur: curcumin; Trans: transfected; Trans + Cur: express transfected + curcumin group.

Figure 6. Effects of curcumin on mitochondrial membrane depolarization levels in transfected and non-transfected SH-SY5Y cells (mean ± SD; n = 8). The values were expressed as fold increase over the control level (experimental/control). a; p < 0.05 vs control group, b; p < 0.05 vs curcumin group, c; p < 0.05 vs transfected group. Cur: curcumin; Trans: transfected; Trans + Cur: express transfected + curcumin group.

Figure 7. Effects of curcumin on caspase 3 (A) and caspase 9 enzyme activity values (B) in SH-SY5Y neuroblastoma cells (mean ± SD; n = 8). The values were expressed as fold increase over the control level (experimental/control). a; p < 0.05 vs control group, b; p < 0.05 vs transfected group. Cur: curcumin; Trans: transfected; Trans + Cur: express transfected + curcumin group.

Figure 8. Effects of curcumin on cell viability levels in SH-SY5Y cells (mean ± SD; n = 8). The values were expressed as fold increase over the control level (experimental/control). a; p < 0.05 vs control group, b; p < 0.05 vs curcumin group, c; p < 0.05 vs transfected group. Cur: curcumin; Trans: transfected; Trans + Cur: express transfected + curcumin group.

Figure 9. Effects of curcumin on apoptosis levels in SH-SY5Y cells (mean ± SD; n = 8). The values were expressed as fold increase over the control level (experimental/control). a; p < 0.05 vs control group, b; p < 0.05 vs curcumin group, c; p < 0.001 vs transfected group. Cur: curcumin; Trans: transfected; Trans + Cur: express transfected + curcumin group.