Preclinical Molecular Imaging, Division of Radiotherapy and Imaging, The Institute of Cancer Research, 123 Old Brompton Road, London, SW7 3RP, UK.
PET Radiochemistry, Division of Radiotherapy and Imaging, The Institute of Cancer Research, 123 Old Brompton Road, London, SW7 3RP, UK.
Sci Rep. 2020 Dec 1;10(1):20918. doi: 10.1038/s41598-020-77788-3.
Targeted radiotherapy with I-mIBG, a substrate of the human norepinephrine transporter (NET-1), shows promising responses in heavily pre-treated neuroblastoma (NB) patients. Combinatorial approaches that enhance I-mIBG tumour uptake are of substantial clinical interest but biomarkers of response are needed. Here, we investigate the potential of F-mFBG, a positron emission tomography (PET) analogue of the I-mIBG radiotracer, to quantify NET-1 expression levels in mouse models of NB following treatment with AZD2014, a dual mTOR inhibitor. The response to AZD2014 treatment was evaluated in MYCN amplified NB cell lines (Kelly and SK-N-BE(2)C) by Western blot (WB) and immunohistochemistry. PET quantification of F-mFBG uptake post-treatment in vivo was performed, and data correlated with NET-1 protein levels measured ex vivo. Following 72 h AZD2014 treatment, in vitro WB analysis indicated decreased mTOR signalling and enhanced NET-1 expression in both cell lines, and F-mFBG revealed a concentration-dependent increase in NET-1 function. AZD2014 treatment failed however to inhibit mTOR signalling in vivo and did not significantly modulate intratumoural NET-1 activity. Image analysis of F-mFBG PET data showed correlation to tumour NET-1 protein expression, while further studies are needed to elucidate whether NET-1 upregulation induced by blocking mTOR might be a useful adjunct to I-mIBG therapy.
靶向放射性碘标记间碘苄胍（I-mIBG）治疗，间碘苄胍是人类去甲肾上腺素转运体（NET-1）的底物，在经过大量预处理的神经母细胞瘤（NB）患者中显示出有希望的反应。增强 I-mIBG 肿瘤摄取的联合治疗方法具有重要的临床意义，但需要反应的生物标志物。在这里，我们研究了 F-mFBG 的潜力，F-mFBG 是 I-mIBG 放射性示踪剂的正电子发射断层扫描（PET）类似物，用于定量 NB 小鼠模型中 NET-1 表达水平，在使用 mTOR 双重抑制剂 AZD2014 治疗后。通过 Western blot（WB）和免疫组织化学分析评估了 AZD2014 治疗在 MYCN 扩增的 NB 细胞系（Kelly 和 SK-N-BE（2）C）中的反应。在体内进行 F-mFBG 摄取的 PET 定量后，将数据与体外测量的 NET-1 蛋白水平相关联。经过 72 小时 AZD2014 治疗后，体外 WB 分析表明两种细胞系的 mTOR 信号均降低，NET-1 表达增强，而 F-mFBG 则显示出 NET-1 功能的浓度依赖性增加。然而，AZD2014 治疗未能在体内抑制 mTOR 信号，也没有显著调节肿瘤内 NET-1 活性。F-mFBG PET 数据的图像分析显示与肿瘤 NET-1 蛋白表达相关，而进一步的研究需要阐明阻断 mTOR 诱导的 NET-1 上调是否可能成为 I-mIBG 治疗的有用辅助手段。
