Experimental Pediatric Oncology, University Children's Hospital of Cologne, Medical Faculty, University of Cologne, Cologne, Germany.
Center for Molecular Medicine Cologne (CMMC), University of Cologne, Cologne, Germany.
Cell Oncol (Dordr). 2022 Oct;45(5):991-1003. doi: 10.1007/s13402-022-00702-8. Epub 2022 Aug 12.
The majority of high-risk neuroblastomas harbor telomerase activity, and telomerase-interacting compounds, such as 6-thio-2'-deoxyguanosine (6-thio-dG), have been found to impair the growth of telomerase-positive neuroblastoma cell lines. It has remained unclear, however, how such drugs can be combined with other compounds used in current treatment concepts for neuroblastoma patients.
Growth-inhibitory effects of varying concentrations of 6-thio-dG in combination with etoposide, doxorubicin or ceritinib were determined in eight telomerase-positive neuroblastoma cell lines with distinct genetic backgrounds. Tumor growth inhibition of subcutaneous xenografts from three different cell lines was assessed upon treatment with 6-thio-dG, the competitive telomerase inhibitor imetelstat, etoposide, or combinations of these compounds.
Robust synergistic anti-tumor effects were observed for combinations of 6-thio-dG and etoposide or doxorubicin, but not for 6-thio-dG and ceritinib, in telomerase-positive neuroblastoma cell lines in vitro. Treatment of mouse xenografts with combinations of 6-thio-dG and etoposide significantly attenuated tumor growth and improved mouse survival over etoposide alone in two of three cell line models. Treatment of xenograft tumors by imetelstat monotherapy decreased telomerase activity by roughly 50% and significantly improved survival over control in all three models, whereas treatment with imetelstat plus etoposide led to enhanced survival over etoposide monotherapy in one model. Mechanistically, the synergistic effect was found to be due to both increased apoptosis and cell cycle arrest.
Our study indicates that telomerase is an actionable target in telomerase-positive neuroblastoma, and demonstrates that combination therapies including telomerase-interacting compounds may improve the efficacy of established cytotoxic drugs. Targeting telomerase may thus represent a therapeutic option in high-risk neuroblastoma patients.
大多数高危神经母细胞瘤具有端粒酶活性，并且已经发现端粒酶相互作用的化合物，如 6-硫代-2'-脱氧鸟苷（6-thio-dG），可损害端粒酶阳性神经母细胞瘤细胞系的生长。然而，目前尚不清楚如何将此类药物与神经母细胞瘤患者当前治疗方案中使用的其他化合物结合使用。
在具有不同遗传背景的 8 种端粒酶阳性神经母细胞瘤细胞系中，确定了不同浓度的 6-thio-dG 与依托泊苷、阿霉素或塞利替尼联合使用的生长抑制作用。通过 6-thio-dG、竞争性端粒酶抑制剂imetelstat、依托泊苷或这些化合物的组合处理来自三个不同细胞系的皮下异种移植肿瘤，评估肿瘤生长抑制作用。
在体外，6-thio-dG 与依托泊苷或阿霉素联合使用对端粒酶阳性神经母细胞瘤细胞系具有强大的协同抗肿瘤作用，但与塞利替尼联合使用则没有。在三种细胞系模型中的两种中，用 6-thio-dG 和依托泊苷的组合治疗小鼠异种移植肿瘤显著减轻肿瘤生长并提高了小鼠的存活率，优于依托泊苷单药治疗。imetelstat 单药治疗降低了异种移植肿瘤中的端粒酶活性约 50%，并在所有三种模型中均显著提高了存活率，而 imetelstat 加依托泊苷治疗在一种模型中提高了依托泊苷单药治疗的存活率。从机制上讲，协同作用是由于细胞凋亡和细胞周期停滞的增加。
我们的研究表明端粒酶是端粒酶阳性神经母细胞瘤的可操作靶点，并证明包括端粒酶相互作用化合物的联合治疗可能提高现有细胞毒性药物的疗效。因此，靶向端粒酶可能是高危神经母细胞瘤患者的一种治疗选择。
