Intratumoral Photodynamic Therapy With Newly Synthesized Pheophorbide a in Murine Oral Cancer

Abstract

Photodynamic therapy (PDT) is a therapeutic alternative for malignant tumors that uses a photosensitizer. Our group recently synthesized photosensitizer pheophorbide a (Pa) from chlorophyll-a. The present study investigated the therapeutic effect of PDT using intratumoral administration of the synthetic photosensitizer Pa in an in vivo murine oral squamous cell carcinoma (OSCC) animal model. Pa accumulation was measured using the fluorescence spectrum and imaging in living C3H mice. Intratumoral treatment of Pa-PDT (IT Pa-PDT) significantly inhibited the growth of transplanted OSCC cells. Histopathological examination of tumor tissues showed that PCNA expression was significantly decreased, while TUNEL-stained cells were markedly increased in the IT Pa-PDT group compared to controls. IT Pa-PDT-induced apoptosis was confirmed by immunoblot. Reduction of Bcl-2 and cleavage of caspase 3 and PARP were observed in IT Pa-PDT. These data demonstrate that IT Pa-PDT inhibited tumor cell proliferation and induced apoptosis, which is correlated with the anticancer activity of IT Pa-PDT. These potent antitumor activities of IT Pa-PDT were observed in both the immunohistochemistry and Western blot experiments. Our findings suggest the intratumoral therapeutic potential of Pa-PDT on OSCC. Additionally, demonstrated detection of Pa using a fluorescence spectroscopy system or molecular imaging system provides a means for simultaneous diagnosis and treatment of OSCC.