DataSheet_1_Lestaurtinib inhibits Citron kinase activity and medulloblastoma growth through induction of DNA damage, apoptosis and cytokinesis failure.pdf

IntroductionMedulloblastoma (MB), the most common malignant pediatric brain tumor, is currently treated with surgery followed by radiation and chemotherapy, which is accompanied by severe side effects, raising the need for innovative therapies. Disruption of the microcephaly-related gene Citron kinase (CITK) impairs the expansion of xenograft models as well as spontaneous MB arising in transgenic mice. No specific CITK inhibitors are available.
MethodsLestaurtinib, a Staurosporine derivative also known as CEP-701, inhibits CITK with IC50 of 90 nM. We therefore tested the biological effects of this molecule on different MB cell lines, as well as in vivo, injecting the drug in MBs arising in SmoA1 transgenic mice.
ResultsSimilar to CITK knockdown, treatment of MB cells with 100 nM Lestaurtinib reduces phospho-INCENP levels at the midbody and leads to late cytokinesis failure. Moreover, Lestaurtinib impairs cell proliferation through CITK-sensitive mechanisms. These phenotypes are accompanied by accumulation of DNA double strand breaks, cell cycle block and TP53 superfamily activation in vitro and in vivo. Lestaurtinib treatment reduces tumor growth and increases mice survival.
DiscussionOur data indicate that Lestaurtinib produces in MB cells poly-pharmacological effects extending beyond the inhibition of its validated targets, supporting the possibility of repositioning this drug for MB treatment.

引言
髓母细胞瘤（Medulloblastoma, MB）是儿童最常见的恶性脑肿瘤，当前临床治疗方案为手术切除联合放疗与化疗，但该疗法伴随严重不良反应，因此亟需开发创新治疗策略。与小头畸形相关的柠康激酶（Citron kinase, CITK）基因功能缺失，会抑制异种移植模型以及转基因小鼠自发形成的髓母细胞瘤的增殖。目前尚无特异性CITK抑制剂。

材料与方法
雷他替尼（Lestaurtinib）是星形孢菌素（Staurosporine）衍生物，亦被称为CEP-701，其对CITK的半数抑制浓度（IC₅₀）为90 nM。为此，我们检测了该分子对不同髓母细胞瘤细胞系的生物学效应，并通过向SmoA1转基因小鼠体内形成的髓母细胞瘤中注射该药物，开展了体内实验研究。

结果
与CITK敲低的实验效果相似，使用100 nM雷他替尼处理髓母细胞瘤细胞，可降低中体处的磷酸化INCENP（phospho-INCENP）水平，并引发胞质分裂晚期失败。此外，雷他替尼可通过CITK敏感通路抑制细胞增殖。上述表型伴随DNA双链断裂积累、细胞周期阻滞以及TP53超家族激活的现象，且该效应在体外与体内实验中均存在。雷他替尼治疗可抑制肿瘤生长并延长小鼠的生存期。

讨论
我们的研究数据表明，雷他替尼在髓母细胞瘤细胞中可产生多药理学效应，其作用范围超出了已验证靶点的抑制范畴，这为将该药物重新定位用于髓母细胞瘤治疗提供了理论依据。