Photodynamic and Sonodynamic Treatment by Phthalocyanine on Cancer Cell Lines

Photodynamic therapy is a modality of treatment for tumors. The photochemical interactions of sensitizer, light and molecular oxygen produce reactive oxygen species (ROS) such as singlet oxygen, peroxide, hydroxyl radical and superoxide ion. The tumor is destroyed either by the formation of highly reactive singlet oxygen (type II mechanism) or by the formation of radical products (type 1 mechanism) generated in an energy transfer reaction. The resulting damage to organelles within malignant cells leads to tumor ablation. The cellular effects include membrane damage, mitochondrial damage and DNA damage. A new treatment modality called sonodynamic therapy has been developed, in which the ultrasound–induced cytotoxicity of sonochemical sensitizers inhibits tumor growth. In this study, the promising new generation of sensitizers – phthalocyanines – were used to induce the photodamage. In addition, we applied an ultrasound treatment to support the photodynamic effect. We report on the production of ROS in G361 melanoma cells. Light-emitting diodes were used to evoke the photodynamic effect. Changes in cells were evaluated using fluorescence microscope and atomic force microscopy. The quantitative ROS production changes in relation to sensitizer concentration, irradiation doses and ultrasound intensity were proved by a fluororeader. Our results showed the highest generation of ROS within G361 melanoma cells was achieved at an irradiation dose of 15 Jcm^-2 followed by ultrasound treatment at intensity of 2 Wcm^-2 and frequency of 1 MHz in the presence of 100 μM chloroaluminum phthalocyanine disulfonate (ClAlPcS₂). These results suggest that ClAlPcS₂ is a potential photosensitizer and sonosensitizer for sonodynamic or photodynamic treatment of cancer. (E-mail: kol@tunw.upol.cz)