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.
Reactive gliosis is a defense mechanism to minimize and repair the initial damage after CNS injuries that is characterized by increases in astrocytic reactivity and proliferation, with enhanced expression of glial fibrillary acidic protein (GFAP) and cellular hypertrophy. Fatty acid binding protein 7 (FABP7) is abundantly expressed in several types of glial cells, such as astrocytes and oligodendrocyte precursor cells, during brain development and FABP7-positive astrocytes have been shown to be significantly increased in the mouse cortex after a stab injury. However, the functional significance of FABP7 in gliosis remains unclear. In the present study, we examined the mechanism of FABP7-mediated regulation of gliosis using an in vitro scratch-injury model using primary cultured astrocytes. Western blotting showed that FABP7 expression was increased significantly in scratch wounded astrocytes at the edge of the injury compared with intact astrocytes. Through monitoring the occupancy of the injured area, FAB7-KO astrocytes showed a slower proliferation rate compared with WT astrocytes after 48 hr, which was confirmed by BrdU immunostaining. There were no differences in cell migration and polarity of reactive astrocytes between FABP-KO and WT. Conclusively, our data suggest that FABP7 is important in the proliferation of reactive astrocytes in the context of CNS injury.