Patients with neuroblastoma due to MYCN oncogene amplification and consequent N‐Myc oncoprotein overexpression have very poor prognosis. The cyclin‐dependent kinase 7 (CDK7)/super‐enhancer inhibitor THZ1 suppresses MYCN gene transcription, reduces neuroblastoma cell proliferation, but does not cause significant cell death. The protein kinase phosphatase 1 nuclear targeting subunit (PNUTS) has recently been shown to interact with c‐Myc protein and suppresses c‐Myc protein degradation. Here we screened the U.S. Food and Drug Administration‐Approved Oncology Drugs Set V from the National Cancer Institute, and identified tyrosine kinase inhibitors (TKIs), including ponatinib and lapatinib, as the Approved Oncology Drugs exerting the best synergistic anticancer effects with THZ1 in MYCN ‐amplified neuroblastoma cells. Combination therapy with THZ1 and ponatinib or lapatinib synergistically induced neuroblastoma cell apoptosis, while having little effects in normal nonmalignant cells. Differential gene expression analysis identified PNUTS as one of the genes most synergistically reduced by the combination therapy. Reverse transcription polymerase chain reaction and immunoblot analyses confirmed that THZ1 and the TKIs synergistically downregulated PNUTS mRNA and protein expression and reduced N‐Myc protein but not N‐Myc mRNA expression. In addition, PNUTS knockdown resulted in decreased N‐Myc protein but not mRNA expression and decreased MYCN ‐amplified neuroblastoma cell proliferation and survival. As CDK7 inhibitors are currently under clinical evaluation in patients, our data suggest the addition of the TKI ponatinib or lapatinib in CDK7 inhibitor clinical trials in patients.

中文翻译：

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CDK7抑制剂和酪氨酸激酶抑制剂的联合治疗对MYCN扩增的神经母细胞瘤具有协同抗癌作用。

由于MYCN致癌基因扩增和随之而来的N-Myc癌蛋白过度表达而导致神经母细胞瘤的患者预后很差。细胞周期蛋白依赖性激酶7（CDK7）/超级增强剂抑制剂THZ1抑制MYCN基因转录，减少神经母细胞瘤细胞增殖，但不会引起明显的细胞死亡。最近已证明蛋白激酶磷酸酶1核靶向亚单位（PNUTS）与c-Myc蛋白相互作用并抑制c-Myc蛋白降解。在这里，我们从美国国家癌症研究所筛选了美国食品药品监督管理局批准的肿瘤药物组V，并确定了酪氨酸激酶抑制剂（TKIs），包括ponatinib和lapatinib，作为与THZ1发挥最佳协同抗癌作用的批准的肿瘤药物MYCN扩增的神经母细胞瘤细胞。THZ1和ponatinib或lapatinib的联合治疗可协同诱导神经母细胞瘤细胞凋亡，而对正常的非恶性细胞几乎没有影响。差异基因表达分析确定了PNUTS是联合疗法中协同作用最强的基因之一。逆转录聚合酶链反应和免疫印迹分析证实，THZ1和TKIs协同下调PNUTS mRNA和蛋白表达，并降低N-Myc蛋白表达，但不降低N-Myc mRNA表达。此外，PNUTS抑制导致N-Myc蛋白减少，但mRNA表达没有减少，MYCN减少放大的神经母细胞瘤细胞增殖和存活。由于目前正在对患者进行CDK7抑制剂的临床评估，因此我们的数据表明，在患者的CDK7抑制剂临床试验中添加了TKI ponatinib或lapatinib。