title: The direct biologic effects of radioactive 125I seeds on pancreatic cancer cells PANC-1, at continuous low-dose rates.
abstract: The relative biologic effectiveness of model 6711 125I seeds (Ningbo Junan Pharmaceutical Technology Company,Ningbo, China) and their effects on growth, cell cycle, and apoptosis in human pancreatic cancer cell line PANC-1 were examined in the present study. PANC-1 cells were exposed to the absorbed doses of 1, 2, 4, 6, 8, and 10 Gyeither with 125I seeds (initial dose rate, 2.59 cGy=h) or with 60Co g-ray irradiation (dose rate, 221 cGy=min),respectively. Significantly greater numbers of apoptotic PANC-1 cells were detected following the continuouslow-dose-rate (CLDR) irradiation of 125I seeds, compared with cells irradiated with identical doses of 60Co g-ray. The D(0) for 60Co g-ray and 125I seed irradiation were 2.30 and 1.66, respectively. The survival fraction after 125Iseed irradiation was significantly lower than that of 60Co g-ray, with a relative biologic effectiveness of 1.39.PANC-1 cells were dose dependently arrested in the S-phase by 60Co g-rays and in the G2=M phase by 125I seeds,24 hour after irradiation. CLDR irradiation by 125I seeds was more effective in inducing cell apoptosis in PANC-1cells than acute high-dose-rate 60Co g irradiation. Interestingly, CLDR irradiation by 125I seeds can cause PANC-1cell-cycle arrest at the G2=M phase and induce apoptosis, which may be an important mechanism underlying 125Iseed-induced PANC-1 cell inhibition.
authors.affiliation: Department of Radiation Oncology, Cancer Center, Peking University Third Hospital, Beijing, China. doctorwangjunjie@yahoo.com.cn
authors.forename: Jidong
authors.initials: J
authors.lastname: Wang
authors.forename: Junjie
authors.initials: J
authors.lastname: Wang
authors.forename: Anyan
authors.initials: A
authors.lastname: Liao
authors.forename: Hongqing
authors.initials: H
authors.lastname: Zhuang
authors.forename: Yong
authors.initials: Y
authors.lastname: Zhao
mesh_terms: D000704:Analysis of Variance; D017209:Apoptosis / Q000187:drug effects / Q000528:radiation effects*; D001918:Brachytherapy / Q000379:methods*; D002453:Cell Cycle / Q000528:radiation effects; D016923:Cell Death / Q000528:radiation effects; D045744:Cell Line, Tumor; D003037:Cobalt Radioisotopes; D004307:Dose-Response Relationship, Radiation; D005434:Flow Cytometry; D006801:Humans; D007457:Iodine Radioisotopes / Q000494:pharmacology*; D010190:Pancreatic Neoplasms / Q000473:pathology / Q000532:radiotherapy*; D011829:Radiation Dosage
chemical_list: D003037:Cobalt Radioisotopes; D007457:Iodine Radioisotopes