Radiosensitizing Effect of P2X7 Receptor Antagonist on Melanoma in Vitro and in Vivo.
Melanoma is highly malignant, and generally exhibits radioresistance, responding poorly to radiation therapy. We previously reported that activation of P2X7, P2Y6, and P2Y12 receptors is involved in the DNA damage response after γ-irradiation of human lung adenocarcinoma A549 cells. However, it is not clear whether these receptors are also involved in the case of melanoma cells, although P2X7 receptor is highly expressed in various cancers, including melanoma. Here, we show that P2X7 receptor antagonist enhances radiation-induced cytotoxicity in B16 melanoma cells in vitro and in vivo. We confirmed that these cells express P2X7 receptor mRNA and exhibit P2X7 receptor-mediated activities, such as ATP-induced pore formation and cytotoxicity. We further examined the radiosensitizing effect of P2X7 receptor antagonist Brilliant Blue G (BBG) in vitro by colony formation assay of B16 cells. γ-Irradiation dose-dependently reduced cell survival, and pretreatment with BBG enhanced the radiation-induced cytotoxicity. BBG pretreatment also decreased the number of DNA repair foci in nuclei, supporting involvement of P2X7 receptor in the DNA damage response. Finally, we investigated the radiosensitizing effect of BBG on B16 melanoma cells inoculated into the hind footpad of C57BL/6 mice. Neither 1 Gy γ-irradiation alone nor BBG alone suppressed the increase of tumor volume, but the combination of irradiation and BBG significantly suppressed tumor growth. Our results suggest that P2X7 receptor antagonist BBG has a radiosensitizing effect in melanoma in vitro and in vivo. BBG, which is used as a food coloring agent, appears to be a promising candidate as a radiosensitizer.
Department of Radiation Biosciences, Faculty of Pharmaceutical Sciences, Tokyo University of Science.|Department of Biochemistry, Faculty of Pharmaceutical Sciences, Tokyo University of Science.
Keisuke
K
Tanamachi
Department of Radiation Biosciences, Faculty of Pharmaceutical Sciences, Tokyo University of Science.|Department of Biochemistry, Faculty of Pharmaceutical Sciences, Tokyo University of Science.
Keisuke
K
Nishino
Department of Radiation Biosciences, Faculty of Pharmaceutical Sciences, Tokyo University of Science.|Department of Biochemistry, Faculty of Pharmaceutical Sciences, Tokyo University of Science.
Natsuki
N
Mori
Research Institute for Biomedical Sciences, Tokyo University of Science.
Toshihiro
T
Suzuki
Department of Biochemistry, Faculty of Pharmaceutical Sciences, Tokyo University of Science.
Sei-Ichi
SI
Tanuma
Research Institute for Biomedical Sciences, Tokyo University of Science.
Ryo
R
Abe
Department of Radiation Biosciences, Faculty of Pharmaceutical Sciences, Tokyo University of Science.
Mitsutoshi
M
Tsukimoto
D000818:Animals; D045744:Cell Line, Tumor; D004249:DNA Damage; D004260:DNA Repair; D005720:Gamma Rays / Q000627:therapeutic use*; D006801:Humans; D008297:Male; D008546:Melanoma, Experimental / Q000378:metabolism / Q000473:pathology / Q000628:therapy*; D008810:Mice, Inbred C57BL; D058920:Purinergic P2X Receptor Antagonists / Q000494:pharmacology / Q000627:therapeutic use*; D011838:Radiation-Sensitizing Agents / Q000494:pharmacology / Q000627:therapeutic use*; D058486:Receptors, Purinergic P2X7 / Q000235:genetics / Q000378:metabolism*; D012394:Rosaniline Dyes / Q000494:pharmacology / Q000627:therapeutic use*; D047368:Tumor Burden / Q000187:drug effects
D058920:Purinergic P2X Receptor Antagonists; D011838:Radiation-Sensitizing Agents; D058486:Receptors, Purinergic P2X7; D012394:Rosaniline Dyes; C004692:coomassie Brilliant Blue
DNA repair; P2X7 receptor; melanoma; radiosensitizer; γ-ray