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

T. Kaneko; M. Tominaga; H. Endo; K. Yaju; R. Kouzaki; H. Yamada; I. Nakanishi; K. Matsumoto; Y. Uto

T. Kaneko Department of Life System, Institute of Technology and Science, Graduate School, Tokushima University, 2-1 Minamijosanjima-cho, 770-8506 Tokushima Japan.
M. Tominaga Department of Radiological Science, Institute of Health Biosciences, Graduate School, Tokushima University, 3-18-15 Kuramoto-cho, 770-8501 Tokushima, Japan.
H. Endo Department of Life System, Institute of Technology and Science, Graduate School, Tokushima University, 2-1 Minamijosanjima-cho, 770-8506 Tokushima Japan.
K. Yaju Department of Life System, Institute of Technology and Science, Graduate School, Tokushima University, 2-1 Minamijosanjima-cho, 770-8506 Tokushima Japan.
R. Kouzaki Department of Life System, Institute of Technology and Science, Graduate School, Tokushima University, 2-1 Minamijosanjima-cho, 770-8506 Tokushima Japan.
H. Yamada Department of Life System, Institute of Technology and Science, Graduate School, Tokushima University, 2-1 Minamijosanjima-cho, 770-8506 Tokushima Japan.
I. Nakanishi Radio-Redox-Response Research Team, Advanced Particle Radiation Biology Research Program, Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, 4-9-1 Anakawa, Inage-ku, 263- 8555 Chiba, Japan.
K. Matsumoto Radio-Redox-Response Research Team, Advanced Particle Radiation Biology Research Program, Research Center for Charged Particle Therapy, National Institute of Radiological Sciences, 4-9-1 Anakawa, Inage-ku, 263- 8555 Chiba, Japan.
Y. Uto Department of Life System, Institute of Technology and Science, Graduate School, Tokushima University, 2-1 Minamijosanjima-cho, 770-8506 Tokushima Japan.

Abstract

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.

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