Analysis of the mechanism underlying radiation-induced jaw bone necrosis

放射性颌骨坏死的机制分析

• 批准号: 10671904
• 负责人: OKADA Yutaka
• 金额: $ 1.98万
• 依托单位: Keio University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1998
• 资助国家: 日本
• 起止时间: 1998 至 2000
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-10671904/
• 关键词: osteoblast-like cell; vitamin D_3; ipriflavone; Hachimijiogan; DNA fragmentation; アポトーシス; 放射線照射; DNA鎖切断; 生細胞率; DNA量; ALP活性; LDH逸脱率; DNA鎖切断率

The mechanism underlying radiation-induced bone necrosis was studied using mouse marrow- derived osteoblast-like cells. Prophylactic drug therapy for such necrosis was also studied.The percentage of osteoblast-like cells that remained viable after radiation exposure was found to correlate with a decrease in the amount of DNA, and the decrease in amount of DNA was correlated with the radiation dose. The DNA cleavage rate, as measured by the fluorescence method, increased as the radiation dose increased. When DNA fragmentation was examined by enzyme immunoassay using BrdU labeling, the amount of DNA fragments in the culture supernatants increased with time, suggesting that the fragments represented cell membrane destruction associated with the loss of cell viability. Analysis of the DNA cleavage patterns using agarose gel electrophoresis revealed nonspecific cleavage of the singlet chain at all radiation dose levels examined. These results suggest that the loss of viability of osteoblasts due to non-specific DNA cleavage induced by radiation underlies radiation-induced bone necrosis. When used independently, ipriflavone markedly elevated the cell viability rate of osteoblast-like cells. Vitamin D_3 exerted a similar effect when used in combination with a herbal preparation named Hachimijiogan. When the effects of these drugs on DNA fragmentation were examined, it was found that the cell membrane remained intact in all of the Hachimijiogan-treated cells which lost their viability following irradiation. Following treatment with ipriflavone, cell necrosis induced by 5 Gy radiation was not associated with cell membrane damage. On the other hand, following treatment with vitamin D_3, cell necrosis induced by radiation was associated with cell membrane damage at all the radiation dose levels examined. These results suggest that treatment with ipriflavone or a combination of vitamin D_3 and Hachimijiogan may be useful for the prevention of radiation-induced bone necrosis.

采用小鼠骨髓源性成骨细胞样细胞研究了放射性骨坏死的机制。研究发现，放射线照射后存活的成骨样细胞的百分率与DNA量的减少有关，DNA量的减少与放射线剂量有关。用荧光法测得的DNA裂解率随辐射剂量的增加而增加。当使用BrdU标记通过酶免疫测定法检查DNA片段化时，培养上清液中的DNA片段的量随时间增加，这表明所述片段代表与细胞活力丧失相关的细胞膜破坏。使用琼脂糖凝胶电泳的DNA裂解模式分析显示，在所有的辐射剂量水平检查的非特异性切割的单线链。这些结果表明，由于辐射诱导的非特异性DNA裂解导致的成骨细胞活力丧失是辐射诱导的骨坏死的基础。当单独使用时，依普黄酮显着提高成骨样细胞的细胞活力率。维生素D_3与一种名为八味地黄的草药制剂合用时也有类似的效果。当检查这些药物对DNA断裂的影响时，发现所有经八见肝处理的细胞的细胞膜保持完整，这些细胞在照射后失去了活力。依普黄酮治疗后，5戈伊辐射诱导的细胞坏死与细胞膜损伤无关。另一方面，在所有剂量水平下，维生素D_3处理后，辐射引起的细胞坏死与细胞膜损伤有关。这些结果表明，依普拉芬或维生素D_3与八极米根联合应用对预防放射性骨坏死可能是有益的。