Strathclyde Institute of Pharmacy and Biomedical Sciences, University of Strathclyde, Glasgow, United Kingdom.
J Nucl Med. 2012 Jul;53(7):1146-54. doi: 10.2967/jnumed.111.095943. Epub 2012 Jun 11.
Targeted radiotherapy using (131)I-metaiodobenzylguanidine ((131)I-MIBG) has produced remissions in some neuroblastoma patients. We previously reported that combining (131)I-MIBG with the topoisomerase I inhibitor topotecan induced long-term DNA damage and supraadditive toxicity to noradrenaline transporter (NAT)-expressing cells and xenografts. This combination treatment is undergoing clinical evaluation. This present study investigated the potential of poly(adenosine diphosphate [ADP]-ribose) polymerase (PARP-1) inhibition, in vitro and in vivo, to further enhance (131)I-MIBG/topotecan efficacy.
Combinations of topotecan and the PARP-1 inhibitor PJ34 were assessed for synergism in vitro by combination-index analysis in SK-N-BE(2c) (neuroblastoma) and UVW/NAT (NAT-transfected glioma) cells. Three treatment schedules were evaluated: topotecan administered 24 h before, 24 h after, or simultaneously with PJ34. Combinations of PJ34 and (131)I-MIBG and of PJ34 and (131)I-MIBG/topotecan were also assessed using similar scheduling. In vivo efficacy was measured by growth delay of tumor xenografts. We also assessed DNA damage by γH2A.X assay, cell cycle progression by fluorescence-activated cell sorting analysis, and PARP-1 activity in treated cells.
In vitro, only simultaneous administration of topotecan and PJ34 or PJ34 and (131)I-MIBG induced supraadditive toxicity in both cell lines. All scheduled combinations of PJ34 and (131)I-MIBG/topotecan induced supraadditive toxicity and increased DNA damage in SK-N-BE(2c) cells, but only simultaneous administration induced enhanced efficacy in UVW/NAT cells. The PJ34 and (131)I-MIBG/topotecan combination treatment induced G(2) arrest in all cell lines, regardless of the schedule of delivery. In vivo, simultaneous administration of PJ34 and (131)I-MIBG/topotecan significantly delayed the growth of SK-N-BE(2c) and UVW/NAT xenografts, compared with (131)I-MIBG/topotecan therapy.
The antitumor efficacy of topotecan, (131)I-MIBG, and (131)I-MIBG/topotecan combination treatment was increased by PARP-1 inhibition in vitro and in vivo.
使用放射性碘标记的间碘苄胍((131)I-MIBG)进行靶向放疗已使一些神经母细胞瘤患者获得缓解。我们之前报道，将(131)I-MIBG 与拓扑异构酶 I 抑制剂拓扑替康联合使用会导致去甲肾上腺素转运体(NAT)表达细胞和异种移植物中的长期 DNA 损伤和超相加毒性。这种联合治疗正在进行临床评估。本研究旨在探讨体外和体内多聚(腺苷二磷酸[ADP]-核糖)聚合酶(PARP-1)抑制作用进一步增强(131)I-MIBG/拓扑替康疗效的潜力。
通过 SK-N-BE(2c)(神经母细胞瘤)和 UVW/NAT(NAT 转染的神经胶质瘤)细胞中的组合指数分析，评估拓扑替康与 PARP-1 抑制剂 PJ34 的联合用药在体外是否具有协同作用。评估了三种治疗方案：拓扑替康在 PJ34 给药前 24 小时、后 24 小时或同时给药。还使用类似的方案评估了 PJ34 和(131)I-MIBG 以及 PJ34 和(131)I-MIBG/拓扑替康的组合。通过肿瘤异种移植物的生长延迟来测量体内疗效。我们还通过γH2A.X 测定法评估 DNA 损伤，通过荧光激活细胞分选分析评估细胞周期进程，并检测处理细胞中的 PARP-1 活性。
在体外，只有拓扑替康和 PJ34 同时给药或 PJ34 和(131)I-MIBG 同时给药才能在两种细胞系中诱导超相加毒性。PJ34 和(131)I-MIBG/拓扑替康的所有预定组合在 SK-N-BE(2c)细胞中均诱导超相加毒性和增加 DNA 损伤，但只有同时给药才能在 UVW/NAT 细胞中诱导增强的疗效。PJ34 和(131)I-MIBG/拓扑替康联合治疗在所有细胞系中均诱导 G2 期阻滞，而与给药方案无关。在体内，与(131)I-MIBG/拓扑替康治疗相比，PJ34 和(131)I-MIBG/拓扑替康同时给药显著延迟 SK-N-BE(2c)和 UVW/NAT 异种移植物的生长。
体外和体内，PARP-1 抑制作用增强了拓扑替康、(131)I-MIBG 和(131)I-MIBG/拓扑替康联合治疗的抗肿瘤疗效。
