Interaction of heavy-ion microbeam and chemotherapeutic agents in vitro

众所周知，高let重离子辐照的相对生物有效性（RBE）高于低let辐射，如x射线。带电粒子的单一疗法已应用于几种肿瘤。我们研究了两种不同放射敏感性的肿瘤细胞系对高let重离子束的敏感性差异，以及顺铂和依托泊苷联合重离子束的增敏作用和机制的差异。依托泊苷与碳束辐照在耐辐射NMT-1R细胞中表现出协同作用。然而，对辐射敏感的NMT-1细胞没有增强作用。另一方面，顺铂对两种细胞系均无增强作用。照射后24小时，碳束+依托泊苷、碳束+顺铂和单独碳束的G2停搏模式无差异。碳束与依托波苷联合照射可增加NMT-1细胞的凋亡数量，抑制Ku70蛋白的表达。重离子微束辐照后存在旁观者效应。

It is known that relative biological effectiveness (RBE) of high-LET heavy-ion irradiation is higher than that of low-LET radiation such as X-ray. Monotherapy of charged particles has been applied for several tumors. We investigate the differences between two tumor cell lines with different radiosensitivities in sensitivity to high-LET heavy ion beam and in sensitizing effect and the mechanism of cisplatin and etoposide in combination with heavy-ion beam. Etoposide showed a synergistic effect in combination with carbon beam irradiation in radioresistant NMT-1R cells. However, there was no enhancement effect in radiosensitive NMT-1 cells. On the other hand, cisplatin had no enhancement in both cell lines. There was no differences in the pattern of G2 arrest among Carbon-beam + etoposide, Carbon-beam + cisplatin, and Carbon-beam alone 24 hours after irradiation. The increase in amount of apoptosis and the inhibition of Ku70 protein expression were found in the combination of carbon beam irradiation and etoposide in NMT-1 cells. There were bystander effects after heavy-ion microbeam irradiation.