Zinc protoporphyrin IX enhances chemotherapeutic response of hepatoma cells to cisplatin

Figure 5 Cytotoxicity of zinc protoporphyrin IX is related to increased oxidative stress. Induction of intracellular ROS was evaluated by flow cytometry by measuring CM-H2DCFDA fluorescence. Each cell line was treated with 10 μmol/L zinc protoporphyrin (ZnPP) IX, 10 μmol/L hemin, and/or 10 μg/mL cis-diaminedichloroplatinum (cisplatin; CDDP) for 24 h. Mean fluorescence intensity was quantified for these treatments. ZnPP IX increased the fluorescence intensity of the cells and drug-induced ROS in liver cancer cell lines compared with controls or cells treated with CDDP alone. In contrast, hemin decreased CDDP-induced ROS in all liver cancer cell lines.