The tumor affinity of chlorin e6 and its sonodynamic effects on non-small cell lung cancer

Objective: Sonodynamic therapy (SDT) is a promising new approach for cancer therapy. The aim of this study was to investigate the tumor affinity of chlorin e6, a photosensitizer, and its sonodynamic effects on NSCLC. Methods: Human lung adenocarcinoma cells SPCA-1 and mice bearing SPCA-1 tumor xenograft were exposed to ultrasound in the presence or absence of chlorin e6. Chlorin e6 distribution was detected by laser scan confocal microscope. Cell apoptosis and necrosis were studied by flow cytometry analysis. Tumor size and weight were measured after different treatments. Results: The concentration of chlorin e6 in tumor tissue was remarkably higher than that in normal muscle near tumor, and the difference was greatest at 18 h (the fluorescence intensity was 5.38-fold higher in tumor than in muscle, P < 0.05). In vivo, ultrasound (0.4-1.6 W/cm(2)) or chlorin e6 (10-40 mg/kg) alone had no remarkable anti-tumor effects, but the combination of ultrasound (1.6 W/cm(2)) with chlorin e6 (SDT) hampered tumor growth significantly (P < 0.05). Intraperitoneal injection of 40 mg/kg chlorin e6 exerted no notable side effect on blood, liver and kidney function. Flow cytometry analysis showed that chlorin e6-mediated sonodynamic effect was mainly through the induction of cell necrosis. Conclusion: Chlorin e6 is a promising sonosensitizer and chlorin e6-mediated SDT may provide a new approach for NSCLC therapy. (C) 2012 Elsevier B.V. All rights reserved.