title: Evaluation of the in vivo radiosensitizing activity of etanidazole using tumor-bearing chick embryo.
abstract: Chick embryos have been used as alternative experimental animals in various research fields, including virology, immunology, toxicology, oncology, and embryology. Until now, there have been no in vivo models using chick embryo to evaluate radiosensitizing activity. Here, the in vivo radiosensitizing activity of etanidazole, a well-known hypoxic cell radiosensitizer, was evaluated using tumor-bearing chick embryo. On the basis of tumor growth, drug administration and X-ray irradiation were performed on day 15 chick embryo, with the endpoint being day 18 chick embryo. In day 15 chick embryo, an X-ray irradiation dose of equal or less than 10 Gy did not cause significant tumor growth suppression. Intravenous administration of equal or less than 1.0 mg of etanidazole did not cause tumor growth suppression. Neither doses of equal or less than 8 Gy of irradiation nor 1.0 mg of etanidazole caused fatality of the chick embryo. On the basis of these results, we evaluated the radiosensitizing effect of a combination treatment with 8 Gy of irradiation and 1.0 mg of etanidazole. As noted above, 1.0 mg of etanidazole alone and 8 Gy of irradiation alone did not show tumor growth suppression. In contrast, a combination treatment with 8 Gy of irradiation and 1.0 mg of etanidazole showed 35% of significant tumor growth suppression. Thus, we succeeded in evaluating the in vivo radiosensitizing activity of etanidazole using tumor-bearing chick embryo. These results suggest that the use of tumor-bearing chick embryo may be part of a promising system for evaluating radiosensitizing activity.
authors: Department of Life System, Institute of Technology and Science, Graduate School, The University of Tokushima, Tokushima, Japan.
authors: Chiaki
authors: C
authors: Abe
authors: Yoshihiro
authors: Y
authors: Uto
authors: Takashi
authors: T
authors: Nakae
authors: Yuuya
authors: Y
authors: Shinmoto
authors: Keiichiro
authors: K
authors: Sano
authors: Hiroko
authors: H
authors: Nakata
authors: Mizue
authors: M
authors: Teraoka
authors: Yoshio
authors: Y
authors: Endo
authors: Hiroshi
authors: H
authors: Maezawa
authors: Shin-ichiro
authors: S
authors: Masunaga
authors: Eiji
authors: E
authors: Nakata
authors: Hitoshi
authors: H
authors: Hori
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000494:pharmacology; D002642:Chick Embryo; D049033:Chorioallantoic Membrane / Q000378:metabolism; D004195:Disease Models, Animal; D004307:Dose-Response Relationship, Radiation; D017341:Etanidazole / Q000494:pharmacology*; D000860:Hypoxia; D051379:Mice; D009369:Neoplasms / Q000532:radiotherapy*; D011838:Radiation-Sensitizing Agents / Q000494:pharmacology; D013997:Time Factors; D014965:X-Rays
chemical_list: D000970:Antineoplastic Agents; D011838:Radiation-Sensitizing Agents; D017341:Etanidazole