title: 5-aminolevulinic acid-induced protoporphyrin IX with multi-dose ionizing irradiation enhances host antitumor response and strongly inhibits tumor growth in experimental glioma in vivo.
abstract: Ionizing irradiation is a well‑established therapeutic modality for malignant gliomas. Due to its high cellular uptake, 5‑aminolevulinic acid (ALA) is used for fluorescence‑guided resection of malignant gliomas. We have previously shown that 5‑ALA sensitizes glioma cells to irradiation in vitro. The aim of the present study was to assess whether 5‑ALA acts as a radiosensitizer in experimental glioma in vivo. Rats were subcutaneously injected with 9L gliosarcoma cells and administered 5‑ALA. The accumulation of 5‑ALA‑induced protoporphyrin IX was confirmed by high‑performance liquid chromatography (HPLC) analysis. Subcutaneous (s.c.) tumors were subsequently irradiated with 2 Gy/day for five consecutive days. In the experimental glioma model, high‑performance liquid chromatography analysis revealed a high level of accumulation of 5‑ALA‑induced protoporphyrin IX in s.c. tumors 3 h after 5‑ALA administration. Multi‑dose ionizing irradiation induced greater inhibition of tumor growth in rats that were administered 5‑ALA than in the non‑5‑ALA‑treated animals. Immunohistochemical analysis of the s.c. tumors revealed that numerous ionized calcium‑binding adapter molecule 1 (Iba1)‑positive macrophages gathered at the surface of and within the s.c. tumors following multi‑dose ionizing irradiation in combination with 5‑ALA administration. By contrast, the s.c. tumors in the control group scarcely showed aggregation of Iba1‑positive macrophages. These results suggested that multi‑dose ionizing irradiation with 5‑ALA induced not only a direct cytotoxic effect but also enhanced the host antitumor immune response and thus caused high inhibition of tumor growth in experimental glioma.
authors.affiliation: Department of Neurosurgery, University of Occupational and Environmental Health, Kitakyushu, Fukuoka 807‑8555, Japan.
authors.forename: Junkoh
authors.initials: J
authors.lastname: Yamamoto
authors.affiliation: Department of Bioengineering, Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Yokohama, Kanagawa 226‑8501, Japan.
authors.forename: Shun-Ichiro
authors.initials: S
authors.lastname: Ogura
authors.affiliation: Department of Surgical Pathology, University of Occupational and Environmental Health, Kitakyushu, Fukuoka 807‑8555, Japan.
authors.forename: Shohei
authors.initials: S
authors.lastname: Shimajiri
authors.affiliation: Department of Neurosurgery, University of Occupational and Environmental Health, Kitakyushu, Fukuoka 807‑8555, Japan.
authors.forename: Yoshiteru
authors.initials: Y
authors.lastname: Nakano
authors.affiliation: Department of Neurosurgery, University of Occupational and Environmental Health, Kitakyushu, Fukuoka 807‑8555, Japan.
authors.forename: Daisuke
authors.initials: D
authors.lastname: Akiba
authors.affiliation: Department of Neurosurgery, University of Occupational and Environmental Health, Kitakyushu, Fukuoka 807‑8555, Japan.
authors.forename: Takehiro
authors.initials: T
authors.lastname: Kitagawa
authors.affiliation: Department of Neurosurgery, University of Occupational and Environmental Health, Kitakyushu, Fukuoka 807‑8555, Japan.
authors.forename: Kunihiro
authors.initials: K
authors.lastname: Ueta
authors.affiliation: SBI Pharmaceuticals Co., Ltd., Minato‑ku, Tokyo 106‑6020, Japan.
authors.forename: Tohru
authors.initials: T
authors.lastname: Tanaka
authors.affiliation: Department of Neurosurgery, University of Occupational and Environmental Health, Kitakyushu, Fukuoka 807‑8555, Japan.
authors.forename: Shigeru
authors.initials: S
authors.lastname: Nishizawa
mesh_terms: D000622:Aminolevulinic Acid / Q000494:pharmacology*; D000818:Animals; D045744:Cell Line, Tumor; D002851:Chromatography, High Pressure Liquid; D003602:Cytotoxicity, Immunologic / Q000187:drug effects* / Q000528:radiation effects*; D004195:Disease Models, Animal; D005910:Glioma / Q000276:immunology* / Q000473:pathology* / Q000628:therapy; D008297:Male; D009336:Necrosis; D010778:Photochemotherapy; D011524:Protoporphyrins / Q000096:biosynthesis* / Q000737:chemistry; D011829:Radiation Dosage; D011839:Radiation, Ionizing; D011838:Radiation-Sensitizing Agents / Q000494:pharmacology*; D051381:Rats; D047368:Tumor Burden / Q000187:drug effects / Q000528:radiation effects
chemical_list: D011524:Protoporphyrins; D011838:Radiation-Sensitizing Agents; D000622:Aminolevulinic Acid; C028025:protoporphyrin IX