The potential role of photodynamic therapy in the treatment of malignant melanoma--an in vitro study.

Background: Melanoma is the most severe of skin neoplasms as it may grow rapidly and metastasize. The application of photodynamic therapy (PDT) opens up new prospects in the treatment of this tumor. Numerous studies suggest that the exposure of tumor cells to PDT can lead to cellular and molecular mechanisms which mediate oxidative stress in cells.
Objectives: The aim of this study was to evaluate in vitro the influence of photodynamic therapy on the human melanoma Me45 cell line.
Material and Methods: Photofrin (Ph) was used as a photosensitizer.
Results: Viability studies have shown that there are significant differences between cells after PDT and cells without irradiation. After 24 hours of incubation with a 20 microg/ml concentration of Ph and with irradiation, less than 20% of the cells survived. In the control (without PDT), 65% of the cells survived.
Conclusions: The mitochondrial localization of Ph is significant, as it may lead to disturbances of mitochondrial transmembrane potential and finally to apoptotic cell death. The expressions of manganese superoxide dismutase and heme oxygenase and the level of carbonyl and thiol groups are indicating factors for oxidative stress in Me45 cells.