Department of Advanced Nuclear Medicine Sciences, Institute for Quantum Medical Science (iQMS), National Institutes for Quantum and Radiological Science and Technology (QST), 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan.
Department of Molecular Imaging and Theranostics, Institute for Quantum Medical Science (iQMS), National Institutes for Quantum and Radiological Science and Technology (QST), 4-9-1 Anagawa, Inage-ku, Chiba 263-8555, Japan.
Int J Mol Sci. 2021 Apr 28;22(9):4622. doi: 10.3390/ijms22094622.
Due to their short-range (2-500 nm), Auger electrons (Auger ) have the potential to induce nano-scale physiochemical damage to biomolecules. Although DNA is the primary target of Auger , it remains challenging to maximize the interaction between Auger and DNA. To assess the DNA-damaging effect of Auger released as close as possible to DNA without chemical damage, we radio-synthesized no-carrier-added (n.c.a.) [Pt]cisplatin and evaluated both its in vitro properties and DNA-damaging effect. Cellular uptake, intracellular distribution, and DNA binding were investigated, and DNA double-strand breaks (DSBs) were evaluated by immunofluorescence staining of γH2AX and gel electrophoresis of plasmid DNA. Approximately 20% of intracellular radio-Pt was in a nucleus, and about 2% of intra-nucleus radio-Pt bound to DNA, although uptake of n.c.a. radio-cisplatin was low (0.6% incubated dose after 25-h incubation), resulting in the frequency of cells with γH2AX foci was low (1%). Nevertheless, some cells treated with radio-cisplatin had γH2AX aggregates unlike non-radioactive cisplatin. These findings suggest n.c.a. radio-cisplatin binding to DNA causes severe DSBs by the release of Auger very close to DNA without chemical damage by carriers. Efficient radio-drug delivery to DNA is necessary for successful clinical application of Auger .
由于其短程范围（2-500nm），俄歇电子（Auger ）有可能对生物分子产生纳米级的物理化学损伤。虽然 DNA 是 Auger 的主要靶标，但仍难以最大限度地提高 Auger 与 DNA 之间的相互作用。为了评估 Auger 释放后尽可能接近 DNA 而不产生化学损伤的情况下对 DNA 的损伤作用，我们放射性合成了无载体添加（n.c.a.）[Pt]顺铂，并评估了其体外性质和 DNA 损伤作用。研究了细胞摄取、细胞内分布和 DNA 结合情况，并通过 γH2AX 的免疫荧光染色和质粒 DNA 的凝胶电泳评估了 DNA 双链断裂（DSB）。约 20%的细胞内放射性 Pt 位于核内，约 2%的核内放射性 Pt 与 DNA 结合，尽管 n.c.a.放射性顺铂的摄取量很低（孵育 25 小时后为 0.6%孵育剂量），导致具有 γH2AX 焦点的细胞频率很低（1%）。然而，与非放射性顺铂不同，一些用放射性顺铂处理的细胞有 γH2AX 聚集。这些发现表明，n.c.a.放射性顺铂与 DNA 结合会导致严重的 DSB，因为 Auger 的释放非常接近 DNA，而不会受到载体的化学损伤。为了成功将 Auger 应用于临床，有必要实现放射性药物向 DNA 的有效输送。
