Fig. 1.

PDT triggers apoptosis, necrosis and ferroptosis-like cell death in A549 cells. a, Mechanistic scheme of the generation of ROS in PDT. S₀, S₁ and S₂ stand for the singlet ground state, the first excited singlet state and the second excited singlet state, respectively. T₁ stands for the first excited triplet state. b, Dose-dependent effect of Lip-1 on cell death triggered under three different HYP-PDT conditions (125 nM-30 min, 2 μM-2 min, 10 μM-2 min). c, Ability of the pan-caspase inhibitor ZVF to prevent A549 cell death induced by PDT using low HYP concentrations. d, Effect of cell-death-suppressing compounds on PDT (2 μM-2min) induced A549 cell death. RIPK1 inhibitor Nec-1 (20 μM), autophagic inhibitor 3-MA (30 mM), pan-caspase inhibitor ZVF (100 μM). e, Relative ATP level in A549 cells treated with RSL3 (10 μΜ, for 8 h), or PDT (2 μM-2 min, 8 h after), or curcumin (CUR, 50 μM, for 8 h), or H₂O₂ (20 mM, for 2 h). PDT induced cell death in A549 cells analyzed by flow cytometry (125 nM-30 min, 2 μM-2 min) in f and trypan blue staining (10 μM-2 min, 30 min after PDT) in g. (For interpretation of the references to color in this figure legend, the reader is referred to the Web version of this article.)