Until recently, green tea polyphenols were considered strong antioxidants. However, the latest reports have revealed that bioflavonoids can play a multiple role in anticancer therapy, including the inhibition of cell proliferation and generation of the oxidative stress in a dose-dependent manner. The presented research was designed to examine the potential of the green tea (±)-catechin as a reinforcement of the electrochemotherapy (ECT) with cisplatin in pancreatic cancer in vitro. The study was performed on two cell lines of the pancreatic ductal adenocarcinoma (PDA) - parental EPP85-181P and multidrug-resistant EPP85-181RNOV. Prior to the ECT protocol the cells were preincubated with high or low concentration of catechin for 2 or 24 hours, respectively. We assessed the influence of preincubation on the cisplatin toxicity with and without electroporation (EP), the electrosensitivity of PDA cell lines and the uptake of the daunorubicin and propidium iodide. Additionally, we evaluated the antioxidative properties of catechin by the measurement of the ROS-related fluorescence and the immunoreactivity of the oxidative stress-related enzymes superoxide dismutase (SOD2) and glutathione S-transferase (GST). We found that co-treatment with catechin can firmly enhance the efficacy of electroporation with cisplatin in vitro. More favorable effect was obtained for 2-hour incubation, which indicates the involvement of the transcriptional-independent mechanisms of catechin action. The effect may be partially explained by the increased oxidative stress level, which was higher in multidrug-resistant cells. However, further studies on cisplatin-catechin interplay and the thorough examination of the catechin-cell membrane interaction need to be performed.
Keywords: in vitro; catechin; cisplatin; electroporation; pancreatic cancer.