Thymidylate synthase inhibitor raltitrexed can induce high levels of DNA damage in MYCN ‐amplified neuroblastoma cells
Thymidylate synthase inhibitor raltitrexed can induce high levels of DNA damage in MYCN ‐amplified neuroblastoma cells
复制标题
胸苷酸合成酶抑制剂雷替曲塞可在 MYCN 扩增的神经母细胞瘤细胞中诱导高水平的 DNA 损伤
DOI：
10.1111/cas.14485
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发表时间：
2020
期刊：
影响因子：
5.7
通讯作者：
Kadomatsu Kenji
中科院分区：
文献类型：
--
作者：
Yamashita Ken;Kiyonari Shinichi;Tsubota Shoma;Kishida Satoshi;Sakai Ryuichi;Kadomatsu Kenji
MYCN基因扩增一直与神经母细胞瘤（一种起源于交感神经系统的儿科肿瘤）患者的不良预后相关。常规抗癌药物，如烷化剂和铂类化合物，已用于治疗MYCN扩增型神经母细胞瘤的高危患者，而分子靶向药物尚未获得批准。因此，高度期望开发安全且有效的治疗方法。虽然胸苷酸合成酶抑制剂被广泛用于结直肠癌和胃癌，但其在神经母细胞瘤中的作用尚未得到充分研究。在此，我们研究了获批的叶酸拮抗剂甲氨蝶呤、培美曲塞和雷替曲塞（RTX）对MYCN扩增和非扩增神经母细胞瘤细胞系的疗效。细胞生长抑制试验显示RTX对MYCN扩增的细胞系显示出上级抑制活性。我们发现，抗叶酸转运蛋白或胸苷酸合成酶（RTX的主要靶点）的蛋白表达水平在细胞系中没有显著差异。由于补充胸苷可以挽救RTX诱导的细胞生长抑制，RTX的作用主要是由于dTTP合成的减少。有趣的是，RTX处理在MYCN扩增的细胞中诱导单链DNA损伤反应的程度比在非扩增的细胞中更大。我们认为，高DNA复制应激和DNA损伤水平升高，这是MYCN靶基因表达失调的结果，可能是对RTX敏感性增加的原因。
MYCNgene amplification is consistently associated with poor prognosis in patients with neuroblastoma, a pediatric tumor arising from the sympathetic nervous system. Conventional anticancer drugs, such as alkylating agents and platinum compounds, have been used for the treatment of high‐risk patients withMYCN‐amplified neuroblastoma, whereas molecule‐targeting drugs have not yet been approved. Therefore, the development of a safe and effective therapeutic approach is highly desired. Although thymidylate synthase inhibitors are widely used for colorectal and gastric cancers, their usefulness in neuroblastoma has not been well studied. Here, we investigated the efficacies of approved antifolates, methotrexate, pemetrexed, and raltitrexed (RTX), onMYCN‐amplified and nonamplified neuroblastoma cell lines. Cell growth‐inhibitory assay revealed that RTX showed a superior inhibitory activity againstMYCN‐amplified cell lines. We found no significant differences in the protein expression levels of the antifolate transporter or thymidylate synthase, a primary target of RTX, among the cell lines. Because thymidine supplementation could rescue the RTX‐induced cell growth suppression, the effect of RTX was mainly due to the reduction in dTTP synthesis. Interestingly, RTX treatments induced single‐stranded DNA damage response inMYCN‐amplified cells to a greater extent than in the nonamplified cells. We propose that the high DNA replication stress and elevated levels of DNA damage, which are a result of deregulated expression ofMYCNtarget genes, could be the cause of increased sensitivity to RTX.