Cell Death by SecTRAPs: Thioredoxin Reductase as a Prooxidant Killer of Cells
Figure 2
Concentration dependent cell death induction by SecTRAPs in two human cancer cell lines and the effects of excess TrxR1.
(A) HeLa and A549 cells were treated with 100 ng rat or human SecTRAPs in the presence or absence of BioPORTER delivery reagent, as indicated in the figure and described in the text. A significant increase in cell death was seen in all cases where SecTRAPs were incubated with the cells in the presence of BioPORTER as compared to addition of SecTRAPs alone (***, p<0.001) (B) A SecTRAP preparation (truncated rat TrxR1) at an amount of 0.1 pg-100 ng was used for delivery into 10,000 A549 cells using BioPORTER, as described in the text. The graph shows the determined cell death (mean value±S.D.) triggered by each SecTRAP amount and significant differences to control treatments are indicated, using as controls either incubation with only TE buffer (white bar: n.s., p>0.05; *, p<0.05; **, p<0.01; ***, p<0.001) or with BioPORTER alone (dashed bar: n.s., p>0.05; ##, p<0.01; ###, p<0.001). No significant difference in cell death was seen comparing the two control treatments with each other. (C) A549 cells were treated with 100 ng full-length TrxR1 or a mixture of different amounts of TrxR1 with 10 ng SecTRAP using BioPORTER, as indicated in the figure. Differences in cell death were compared to control cells either treated with TE buffer (white bar; **, p<0.01; ***, p<0.001) or with only BioPORTER (dashed bar; ###, p<0.001). No statistically significant difference in cell death was seen between the two control treatments or in comparisons of either control with the treatment using 100 ng TrxR1 (n.s., p>0.05). In all experiments (A–C) cells were incubated for 4 h with the separate treatments and were subsequently stained with Hoechst 33342 and PI for evaluation of dead cells as described in the text.