Fig. 4.

Effects of NIR-PIT with rova-IR700 on SCLC cell lines in vitro.

(a) Microscopic observations before and after DLL3-targeted NIR-PIT. DLL3-expressing SCLC cells were incubated with rova-IR700 for 6 h and observed with a microscope before and after irradiation with NIR light (4 J/cm²). Necrotic cell death was observed after exposure to NIR light (20 min after NIR-PIT). Scale bars, 20 μm.

(b) Target cell- (SBC5-DLL3-luc-GFP) and non-target cell-expressing RFP (3T3-RFP, mouse fibroblasts) were co-cultured with rova-IR700 for 6 h in the same dish and observed with a microscope before and after NIR light irradiation (4 J/cm²). Selective targeted cell death was detected with Sytox Blue dead cell staining, while 3T3-RFP cells remain unchanged after exposure to NIR light (20 min after PIT). Scale bars, 20 μm.

(c) Membrane damage after DLL3-targeted NIR-PIT was measured by counting dead cells stained with propidium iodide, which increased in a light-dose dependent manner. Data are means ± SEMs (n ≥ 4, *p < 0.05, **p < 0.01 [t-test]).

(d) Luciferase activity in SBC5-DLL3-luc-GFP and 3T3-DLL3-luc-GFP cells was measured in RLUs, which decreased in a NIR light dose-dependent manner. Data are means ± SEMs (n ≥ 3, *p < 0.05, **p < 0.01 [t-test]). GFP, green fluorescent protein; NIR, near infrared; PIT, photoimmunotherapy; RFP, red fluorescent protein; RLU, relative light unit; SCLC, small cell lung cancer.