不同分割照射方式对MDA-MB-231移植瘤增殖活性的影响

Bio-Effects of Different Irradiation Regimens on Xenograft of MDA-MB-231 Breast Carcinoma

目的以相同剂量下,研究单次大剂量照射对MDA-MB-231乳腺癌移植瘤的生物学效应。方法建立MDAMB-231乳腺癌移植瘤模型,待移植瘤直径达8~9mm,随机分为0Gy组(空白对照组)、8Gy组(8Gy/1f/1d)、10Gy组(10Gy/1f/1d)、4×2Gy组(8Gy/4f/4d)、2Gy×5(10Gy/5f/5d)组。每3天观察肿瘤体积变化,绘制移植瘤生长曲线。照射实验组(除对照组)裸鼠分别于放疗结束后第7天、14天行18F-FDG PET/CT检查,另取各实验组裸鼠分别于放疗结束后7天、14天处死,收集肿瘤组织行免疫组化测定Ki-67的表达。结果单次大剂量和常规分割照射均能抑制MDA-MB-231移植瘤生长,以单次大剂量10Gy组最为明显(P<0.05)。且在同等剂量条件下,单次大剂量组在放疗后第7、14天PET/CT检查显示移植瘤SUVmax值均低于常规分割照射组(P<0.05),Ki-67阳性细胞百分比单次大剂量组也低于同剂量常规分割组(P<0.05)。结论在同等剂量情况下,单次大剂量放疗较常规分割放疗对MDA-MB-231乳腺癌细胞增殖活性的抑制更为显著,同时18F-FDG PET/CT在一定程度上可以反应早期放疗后MDA-MB-231乳腺癌细胞增殖活性。

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 18 F - 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 cells by immunohistoehemistry 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 ceils after irradiation.