PcGal16 generates ROS and produces toxicity after PDT.

Photocytotoxic effects after PcGal16-PDT in HT-1376 and UM-UC-3 cells evaluated 24 h after PDT using the MTT assay (panel A). The percentage of toxicity was calculated relatively to control cells (cells incubated with PBS and irradiated). Data are the mean ± S.D. of at least three independent experiments performed in triplicates. *(p<0.05), **(p<0.001), ***(p<0.0001) significantly different from control cells. Irradiation dose-dependent cell death in response to PDT with PcGal16 (panel B). Cytotoxicity was assessed 24 h after treatment using the MTT assay. The percentage of cytotoxicity was calculated relatively to control cells (untreated cells). Data are the mean value ± S.D. of at least three independent experiments performed in triplicates. *(p<0.05), **(p<0.001), ***(p<0.0001) significantly different from control cells. Representative fluorescence images (panel C) and quantification (panel D) of DCF fluorescence increase (as a measure of ROS production) in HT-1376 and UM-UC-3 cells, after PDT with PcGal16. Scale bars 20 µm. Data are the mean ± S.D. of at least three independent experiments performed in triplicates. *(p<0.05), ***(p<0.0001) significantly different from control cells Photocytotoxicity after PDT with PcGal16 in the presence of 50 nM of ROS quenchers (sodium azide, histidine and cysteine) in HT-1376 and UM-UC-3 cells (panel E). Cytotoxicity was assessed 24 h after treatment using the MTT assay. The percentage of cytotoxicity was calculated relatively to control cells (untreated cells). Data are the mean value ± S.D. of at least three independent experiments performed in triplicates. ***(p<0.0001) significantly different from MTT reduction (%) after PcGal16-PDT.