ABSTRACT
Objective To explore the bio-effects of high single-dose irradiation on MDA-MB-231 xenografts under the same radiation dose.Method Female BALB/c-nu mice bearing 8-9 mm MDA-MB-231 xenografts were randomized into 5 groups:0Gy group (blank control group),high single-dose 8Gy group (8Gy/one fraction/day),high single-dose 10Gy group (10Gy/one fraction/ day),conventional radiation 2Gy × 4 group (8Gy/4 fraction/4d),conventional radiation 2Gy × 5 group (10Gy/5 fraction/5d).The volumes of gross tumors on nude mice were observed every three days.The tumor growth curve of transplanted tumor were also drawn.The 18F -FDG PET/CT imaging of mice bearing MDA-MB-231 xenografts from all radiation groups were performed with detecting the Ki-67 expressions of tumor ceils by immunohistochemistry at 7days and 14days after final irradiation.Results Compared to control group,the tumor growth of all radiation groups were delayed after radiation,especially single high-dose 10Gy groups (P ＜ 0.05).At 7days and 14days after final radiation,the SUVmax (the maximal standardized uptake value) of xenografts in high single-dose groups was lower than that in conventional fractional groups (P ＜ 0.05) under the same radiation dose.And the percent of Ki-67 positive cells after high single-dose irradiation were less than fractioned irradiation at 7,14days after final radiation (P ＜ 0.05).Conclusion At the same dose,high single-dose irradiation inhibits the growth of MDA-MB-231 xenografts more than conventional fraction irradiation.PET/CT also could evaluated the early changes of proliferation activities of MDA-MB-231 breast cancer cells after irradiation.