Fig. 5: MB-PDT-induced LMP is involved on cell death of breast cells.

A Cells were submitted or not to MB-PDT and cytosolic cathepsin B activity was analyzed after 1, 3, or 24 h of cell treatment. ****p < 0.0001, ***p < 0.001, **p < 0.005, *p < 0.05 vs. Control. B MCF-10A, C MCF-7, and D MDA-MB-231 cells were pretreated or not with CA-074 and then submitted or not to MB-PDT. Cell death was analyzed after 1, 3, 24 h of cell irradiation: ***p < 0.001, **p < 0.005, *p < 0.05 vs. MB-PDT. E Representative images of western blottings of pMLKL, MLKL, and tubulin of BC treated or not with CA-074 and MB-PDT after 24 h, as indicated. F pMLKL/MLKL ratio of cells after 24 h they were treated or not with CA-074 and then submitted to MB-PDT. **p < 0.005 vs. Control. Dot colors representation: MCF-10A in red, MCF-7 in green, and MDA-MB-231 in blue. n ≥ 3 independent experiments. Graph results are presented as mean ± SEM. G Cell death mechanisms activated by MB-PDT in BC ranging from non-malignant to very aggressive tumorigenic cells (from right to left). Upper part shows that photo-oxidation induces membrane lipid profile changes such as lipid peroxidation, LMP, and/or pMLKL pore formation. Bottom part of the figure represents the differential lipid composition of each BC analyzed (represented by different lipid membrane colors) and which mechanisms are activated in each one (LDCD: lysosome-dependent cell death, necroptosis, or ferroptosis). MDA-MB-231 cells: dark gray background, with higher proportion of lipids to undergo lipid peroxidation, MCF-7: gray background displaying lipids not susceptible to peroxidation, MCF-10A: yellow background and bearing intermediate abundance of lipids being susceptible to oxidation.