Wogonin derivative V8 enhances bortezomib efficacy in gastric carcinoma by disrupting lysosome-mediated drug resistance

Figure 3 V8 induces lysosomal cell death in gastric cancer cells. A: Structure of synthetic flavonoid derivate V8; B and C: Gastric cancer cells were treated with V8 at indicated concentration for 24 hours. Representative images (B) and quantified data (C) for cell death are shown; D and E: MGC-803 cells were treated with V8 and L-leucyl-L-leucine methyl ester hydrochloride (1 mmol/L) for 6 hours, followed by staining with LysoSensor Green DND-189 dye. Representative images (D) and quantification data (E) are shown; F and G: MGC-803 cells were treated with V8 (9 μM), followed by staining with LysoTracker red dye. Representative images and quantified intensity of immunofluorescence analysis are shown (scale bar: 25 μm); H-K: MGC-803 cells were transfected with small interfering RNA against CSTB gene or treated with bafilomycin A1 (100 nM), followed by V8 (12 μM) for 24 hours. Representative images (H and J) and quantification data (I and K) of flow cytometry analysis for cell death are shown. ^aP < 0.05. ^bP < 0.01. ^cP < 0.001. ^dP < 0.0001. V-FITC: Annexin V-fluorescein isothiocyanate; PI: Propidium iodide; LLOMe: L-leucyl-L-leucine methyl ester hydrochloride; DMSO: Dimethyl sulfoxide; MFI: Mean fluorescence intensity; DAPI: 4’,6-Diamidino-2-phenylindole; NS: No significance; Baf-A1: Bafilomycin A1; siCtrl: Negative control small interfering RNA; siCTSB: Small interfering RNA targeting CTSB.