The Direct Biologic Effects of Radioactive I-125 Seeds on Pancreatic Cancer Cells PANC-1, at Continuous Low-Dose Rates

The relative biologic effectiveness of model 6711 I-125 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 Gy either with I-125 seeds (initial dose rate, 2.59 cGy/h) or with Co-60 gamma-ray irradiation (dose rate, 221 cGy/min), respectively. Significantly greater numbers of apoptotic PANC-1 cells were detected following the continuous low-dose-rate (CLDR) irradiation of I-125 seeds, compared with cells irradiated with identical doses of Co-60 gamma-ray. The D-0 for Co-60 gamma-ray and I-125 seed irradiation were 2.30 and 1.66, respectively. The survival fraction after I-125 seed irradiation was significantly lower than that of Co-60 gamma-ray, with a relative biologic effectiveness of 1.39. PANC-1 cells were dose dependently arrested in the S-phase by Co-60 gamma-rays and in the G2/M phase by I-125 seeds, 24 hour after irradiation. CLDR irradiation by I-125 seeds was more effective in inducing cell apoptosis in PANC-1 cells than acute high-dose-rate Co-60 gamma Irradiation. interestingly, CLDR irradiation by I-125 seeds can cause PANC-1 cell-cycle arrest at the G2/M phase and induce apoptosis, which may be an important mechanism underlying I-125 seed-induced PANC-1 cell inhibition.http://gateway.webofknowledge.com/gateway/Gateway.cgi?GWVersion=2&SrcApp=PARTNER_APP&SrcAuth=LinksAMR&KeyUT=WOS:000269156300003&DestLinkType=FullRecord&DestApp=ALL_WOS&UsrCustomerID=8e1609b174ce4e31116a60747a720701OncologyMedicine, Research & ExperimentalPharmacology & PharmacyRadiology, Nuclear Medicine & Medical ImagingSCI(E)PubMed3ARTICLE4409-4162