Molecular characterization of photosensitizer-mediated photodynamic therapy by gene expression profiling.

Photodynamic therapy (PDT) is a novel cancer treatment based on the tumor-specific accumulation of a photosensitizer followed by irradiation with visible light, which induces selective tumor cell death via production of reactive oxygen species. To elucidate the underlying mechanisms, microarray analysis was used to analyze the changes in gene expression patterns during PDT induced by various photosensitizers. Cancer cells were subjected to four different photosensitizer-mediated PDT and the resulting gene expression profiles were compared. We identified many differentially expressed genes reported previously as well as new genes for which the functionfunctions in PDT are still unclear. Our current results not only advance the general understanding of PDT but also suggest that distinct molecular mechanisms are involved in different photosensitizer-mediated PDT. Elucidating the signaling mechanisms in PDT will provide information to modulate the antitumor effectiveness of PDT using various photosensitizers.