Photodynamic therapy (
PDT) uses
photosensitizer activation by light of a specific wavelength, and is a promising treatment for various
cancers; however, the detailed mechanism of
PDT remains unclear. Therefore, we investigated the anticancer effect of
PDT using a novel
phosphorus tetraphenylporphyrin (Ptpp) in combination with light emitting diodes (Ptpp-
PDT) in the NOZ human biliary
cancer cell line. Cell viability and apoptosis were examined by MTT assay, flow cytometry and TUNEL assay for 24 hr after Ptpp-
PDT. MitoTracker and
JC-1 were used as markers of mitochondrial localization and membrane potential. The levels of mitochondrial oxidative phosphorylation (OXPHOS) complexes, Bcl-2 family
proteins,
cytochrome c and cleaved
caspase-3 were examined by western blotting and immunohistochemistry. The results revealed that Ptpp localized to mitochondria, and that Ptpp-
PDT efficiently decreased cell viability in a dose- and time-dependent manner.
JC-1 and OXPHOS complexes decreased, but apoptotic cells increased from 6 to 24 hr after Ptpp-
PDT. A decrease in Bcl-xL and increases in Bax,
cytochrome c and cleaved
caspase-3 were also found from 6 to 24 hr after Ptpp-
PDT. Based on these results, we conclude that Ptpp-
PDT induces anticancer effects via the mitochondrial apoptotic pathway by altering the Bax/Bcl-xL ratio, and could be an effective treatment for human biliary
cancer.