Skip to main content
. 2019 Sep 26;9:13931. doi: 10.1038/s41598-019-50329-3

Figure 12.

Figure 12

Further details of process #3. Process #3 was established either by treating tumor cells with CAP for 1 min, followed by an immediate washing step and further incubation in fresh medium. During CAP treatment, the tumor cells were not confronted with inhibitors (A), or with 100 µM of the NOX1 inhibitor AEBSF (B) or AEBSF plus 25 µM of the ONOO decomposition catalyst FeTPPS (C). As indicated, assays contained additional histidine or FeTPPS, either during CAP treatment, or during the incubation phase following the washing step. Control assays without CAP treatment did not show apoptosis induction above 4% (data not shown). The results show that process #3 is initiated by primary singlet oxygen from the gaseous phase of CAP, independent of H2O2/NO2-dependent primary 1O2 (as the effect was not inhibited by FeTPPS during treatment) and independent of secondary 1O2, as it was not inhibited by AEBSF. However, the imprinted signature induced by primary 1O2 from the gaseous phase of CAP allowed the generation of secondary 1O2 after washing, as seen by the inhibitory effects of histidine and FeTPPS.