| Summary: | 碩士 === 中原大學 === 生物醫學工程研究所 === 103 === Photodynamic therapy (PDT) is a modality for cancers using photosensitizers that are specifically accumulated in diseased tissue. Upon exposure to light with specific wavelength, they produce reactive oxygen species and become toxic to targeted malignant cells. The aim of this study was to investigate the PDT effects on EMT6 murine mammary cancer cells and EMT6-tumor bearing mice in the presence of pheophorbide a (pho a) and 660 nm light emitting diodes (LED) irradiation. First, half lethal dose (LD50) under different incubation time with pho a and different light dose was obtained by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. LD50 is 8.2±3.5 ng/mL with radiant exposure of 2.55 J/cm2 and 3.5±0.2 ng/mL with radiant exposure of 5.10 J/cm2. Wound healing assay was used to determine the effect Pho a-PDT on cell migration. The results showed that PDT after 2-hr incubation with Pho a had no effect on EMT6 cell migration. Incubation time of 4 hours and radiant exposure of 5.10 J/cm2 increased cell migration ability. Six-hour coculture and radiant exposure of 2.55 J/cm2 also increased cell migration ability. Next, transwell cell migration and invasion assays showed that transmembrane migration and invasion ability decreased with the increase of coculture time with Pho a and light dose. EMT6 cells exhibited the phenomenon of necrosis such as swollen nuclei and double staining with annexin/propidium iodide after PDT. Necrotic cell population increased with the increase of coculture time with Pho a and light dose. EMT6-bearing mice injected 2 mg/mL Pho a by tail vein, and irradiated with 10.2 J/cm2 exhibited slower tumor growth. Fractional-Photodynamic therapy (F-PDT) further decreased the tumor growth. In summary, Pho a-PDT possesses cytotoxicity on EMT6 cells, and slows down tumor growth in EMT6-bearing mice, which may be used as an adjunct therapy for cancer treatment.
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