RADIOSENSITIZING EFFECT OF PROTOPORPHYRIN IX WITH CARBON ION BEAM AGAINST MOUSE MAMMARY BREAST TUMOR CELL

5-aminolevulinic acid (ala), a precursor of protoporphyrin ix (ppix), has been utilized as a potent sensitizer for photodynamic therapy (pdt) of cancer through production of reactive oxygen species (ros). ala also has been proposed as a possible radiosensitizer with low linear energy transfer (let) radiation because antitumor activity of low-let radiation depends on ros mainly. in this paper, we investigated the radiosensitizing activity of ppix in carbon ion irradiation as a high let radiation. ppix was detected in an emt6 mouse mammary breast tumor cells even at 24 h post treatment. the cytotoxicity of ppix against emt6 cells was ic50 = 48.0 μm. the combined treatment of 1.0 μm of ppix with 2 gy of carbon ion irradiation (290 mev/nucleon, 85.1 kev/μm) showed a more potent antitumor activity than carbon ion irradiation alone. we demonstrated that ppix showed a radiosensitizing effect with carbon ion beam against mouse mammary breast tumor cells.