Madsen Steen J, Sun Chung-Ho, Tromberg Bruce J, Yeh Alvin T, Sanchez Rogelio, Hirschberg Henry
Photochem Photobiol. 2002 Oct;76(4):411-6. doi: 10.1562/0031-8655(2002)076<0411:eocpta>2.0.co;2.
The effects of combined photodynamic therapy (PDT) and ionizing radiation are studied in a human glioma spheroid model. The degree of interaction between the two modalities depends in a complex manner on factors such as PDT irradiation fluence, fluence rate and dose of ionizing radiation. It is shown that gamma radiation and PDT interact in a synergistic manner only if both light fluence and gamma radiation dose exceed approximately 25 J cm(-2) and 8 Gy, respectively. Synergistic interactions are observed only for the lower fluence rate (25 mW cm(-2)) investigated. The degree of interaction appears to be independent of both sequence and the PDT or ionizing radiation time intervals investigated (1 and 24 h). Terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling assays show that low-fluence rate PDT is very efficient at inducing apoptotic cell death, whereas neither high-fluence rate PDT nor ionizing radiation produces significant apoptosis. Although the mechanisms remain to be elucidated, the data imply that the observed synergism is likely not due to gamma-induced cell cycle arrest or to PDT-induced inhibition of DNA repair.
在人胶质瘤球体模型中研究了联合光动力疗法（PDT）和电离辐射的效果。这两种治疗方式之间的相互作用程度以复杂的方式取决于多种因素，如PDT照射通量、通量率以及电离辐射剂量。结果表明，只有当光通量和γ辐射剂量分别超过约25 J cm(-2)和8 Gy时，γ辐射与PDT才会以协同方式相互作用。仅在研究的较低通量率（25 mW cm(-2)）下观察到协同相互作用。相互作用程度似乎与所研究的顺序以及PDT或电离辐射的时间间隔（1小时和24小时）均无关。末端脱氧核苷酸转移酶介导的脱氧尿苷三磷酸缺口末端标记分析表明，低通量率PDT在诱导凋亡性细胞死亡方面非常有效，而高通量率PDT和电离辐射均未产生明显的凋亡。尽管机制仍有待阐明，但数据表明观察到的协同作用可能并非由于γ诱导的细胞周期停滞或PDT诱导的DNA修复抑制。
