Chandra Subhash, Kabalka George W, Lorey Daniel R, Smith Duane R, Coderre Jeffrey A
Department of Chemistry and Chemical Biology, Cornell University, Ithaca, New York 14853-1301, USA.
Clin Cancer Res. 2002 Aug;8(8):2675-83.
There is a clear need for a technique that provides subcellular locations of fluorine and boron atoms from fluorinated neutron capture agents because positron emission tomography is being tested as a tool for providing tumor boron concentrations in boron neutron capture therapy.
Ion microscopy was used in combination with confocal laser scanning microscopy to investigate the subcellular locations of fluorine and boron from fluorinated p-boronophenylalanine (F-BPA) in human glioblastoma T98G cells. The fluorinated compound was also compared with p-boronophenylalanine (BPA) for delivery of boron after a clinically relevant 6-h exposure. Mitochondria were identified by rhodamine 123 labeling. A strict cryogenic sample preparation was used, and measurements were made in fractured freeze-dried cells.
The nucleus, a perinuclear mitochondria-rich cytoplasmic region, and the remaining cytoplasm were the three subcellular regions identified in individual T98G cells. In cells treated with F-BPA, the mitochondria-rich perinuclear cytoplasmic region exhibited significantly lower fluorine and boron signals than the remaining cytoplasm and the nuclei. Ion microscopy observations revealed a nearly 1:1 distribution of fluorine and boron in subcellular compartments. Quantitative subcellular observations indicated that there was no significant difference in boron delivery to subcellular compartments between the F-BPA and nonfluorinated BPA.
These observations provide the first direct evidence that fluorine and boron from fluorinated BPA are cocompartmentalized in cells and that the fluorinated compound is as efficient for boron delivery as the nonfluorinated BPA at a clinically relevant time point. These observations provide strong support for the use of F-BPA in positron emission tomography biodistribution studies for boron neutron capture therapy.
由于正电子发射断层扫描正在作为一种在硼中子俘获疗法中提供肿瘤硼浓度的工具进行测试，因此迫切需要一种能够提供来自氟化中子俘获剂的氟和硼原子亚细胞定位的技术。
离子显微镜与共聚焦激光扫描显微镜联合使用，以研究氟化对硼苯丙氨酸（F-BPA）中的氟和硼在人胶质母细胞瘤T98G细胞中的亚细胞定位。在临床相关的6小时暴露后，还将该氟化化合物与对硼苯丙氨酸（BPA）进行硼递送比较。通过罗丹明123标记鉴定线粒体。使用严格的低温样品制备方法，并在断裂的冻干细胞中进行测量。
细胞核、富含线粒体的核周细胞质区域和其余细胞质是在单个T98G细胞中鉴定出的三个亚细胞区域。在用F-BPA处理的细胞中，富含线粒体的核周细胞质区域的氟和硼信号明显低于其余细胞质和细胞核。离子显微镜观察显示亚细胞区室中氟和硼的分布接近1:1。亚细胞定量观察表明，F-BPA和非氟化BPA之间向亚细胞区室递送硼没有显著差异。
这些观察结果提供了首个直接证据，即氟化BPA中的氟和硼在细胞中共定位，并且在临床相关时间点，氟化化合物在硼递送方面与非氟化BPA一样有效。这些观察结果为F-BPA在用于硼中子俘获疗法的正电子发射断层扫描生物分布研究中的应用提供了有力支持。
