Photodynamic therapy with zinc-tetra(p-sulfophenyl)porphyrin bound to cyclodextrin induces single strand breaks of cellular DNA in G361 melanoma cells.

The basis of photodynamic therapy (PDT) is the phototoxicity resulting from co-action of light, sensitizer and oxygen. In this study we demonstrate in vitro phototoxicity measurement on G361 cell lines using ZnTPPS(4) sensitizer bound to cyclodextrin hpbetaCD. We have proved its photodamage effect on cancer cell lines in the visible region of spectrum. We used the halogen lamp (24V/250W) as a source of radiation. After 24h incubation of cell cultures with 10 microM ZnTPPS(4) and 1mM cyclodextrine hpbetaCD, the cells were irradiated for 7.5 min at the total irradiation dose of 12.5 Jcm(-2). Analysis of DNA damage in the cell line after PDT was proved by comet assay and using inversion fluorescent microscope with image analysis. This treatment method gave rise to DNA damage. The used radiation dose of visible light in the absence of sensitizers does not induce DNA breaks in tumour cells. In conclusion, binding of ZnTPPS(4) sensitizer to cyclodextrin hpbetaCD may improve the efficacy of PDT for the treatment of malign melanoma.