Fig. 6
Combination of PIT and Nal–IRI in OVCAR-5 and U87 cells. a Cells were incubated with PIC–Nal–IRI or controls at a fixed BPD (1 µM) and irinotecan (7 µM) concentration for 48 h prior to light activation (690 nm, 10 mW/cm2, 0–0.6 J/cm2). b OVCAR-5 viability and c U87 viability were determined by MTT assay at 24 h post-light activation. The IC50 values of PIC–Nal are ~ 0.6 μM × J/cm2 and ~ 0.35 μM × J/cm2 for d OVCAR-5 and e U87 cells, respectively. d, e The reduction of cell viability was compared among the treatment groups. f, g Combination index (CI) was determined using CompuSyn software. The CI value quantitatively defines synergism (CI < 1), additive effect (CI = 1) and antagonism (CI > 1) effect of light-activated PIC–Nal–IRI in OVCAR-5 and U87 cells. (n > 3; *P < 0.05, ***P < 0.001; n.s.: not significant; one-way ANOVA, Tukey’s post hoc test)