导读：彭小忠课题组于2019年5月21日在《J Clin Invest.》杂志上发表研究论文“The antibiotic clofoctol suppresses glioma stem cell proliferation by activating KLF13”。研究者发现了一种临床上用于治疗上呼吸道感染的药物——氯福克酚可以“老药新用”，通过特异抑制胶质瘤干细胞，发挥对胶质瘤的治疗效果。同时该研究也对氯福克酚的药物靶点和下游调控的关键基因进行了探寻，解析了其抗胶质瘤的具体作用机制。 

文章链接：https://www.jci.org/articles/view/124979 

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      胶质瘤干细胞的存在是肿瘤产生放化疗抵抗，导致肿瘤复发的关键因素，被认为是神经胶质瘤难以被攻克的一个主要原因。该研究利用胶质瘤干细胞进行药物筛选，以期获得新一代治疗神经胶质瘤的有效药物，改善其治疗现状。 

      首先，研究团队以四株胶质瘤干细胞为模型，并结合细胞共培养，斑马鱼毒性检测等实验对MicroSource Spectrum化合物库中的1920种化合物进行筛选，发现氯福克酚可特异性抑制胶质瘤干细胞的活性。超高效液相色谱-质谱分析结果显示氯福克酚可透过血脑屏障，通过裸鼠皮下和原位移植瘤模型、胶质瘤转基因小鼠模型及裸鼠PDX等模型证实了氯福克酚对胶质瘤的在体治疗效果。 

      随后，为了深入解析氯福克酚抑制胶质瘤干细胞的具体机制，该团队利用基因芯片分析药物作用前后基因的表达差异，发现氯福克酚可上调KLF13（Kruppel-like factor 13）的表达。进一步细胞功能学实验结果显示，敲低KLF13后胶质瘤干细胞的肿瘤球形成及自我更新能力皆有所增强。同时，他们发现敲低KLF13可拮抗氯福克酚对胶质瘤干细胞的抑制作用。而过表达KLF13可明显抑制胶质瘤干细胞的生长、肿瘤球形成及自我更新能力，并促进氯福克酚对胶质瘤干细胞的作用效果。由此说明氯福克酚可通过上调KLF13的表达发挥对胶质瘤干细胞的抑制作用。 

       为了进一步探究氯福克酚上调KLF13表达的分子机制，研究人员借助了一种新的药物靶蛋白探寻技术——DARTS（Drug affinity responsive target stability）并结合等温滴定量热法(ITC)实验找到了药物结合的靶蛋白。结果显示，氯福克酚可通过与UNR（Upstream-of-N-Ras）蛋白相互结合，增强UNR蛋白与KLF13 mRNA的结合能力，提高KLF13 mRNA的稳定性，进而诱导KLF13的表达上调。以上研究结果提示RNA结合蛋白UNR可作为胶质瘤治疗靶点，并揭示了其下游基因KLF13在胶质瘤发生发展及预后过程中的重要作用。 

【摘要】Gliomas account for approximately 80% of primary malignant tumors in the central nervous system. Despite aggressive therapy, the prognosis of patients remains extremely poor. Glioma stem cells (GSCs) which considered as the potential target of therapy for their crucial role in therapeutic resistance and tumor recurrence, are believed to be key factors for the disappointing outcome. Here, we took advantage of GSCs as the cell model to perform high-throughput drug screening and the old antibiotic, clofoctol, was identified as the most effective compound, showing reduction of colony-formation and induction of apoptosis of GSCs. Moreover, growth of tumors was inhibited obviously in vivo after clofoctol treatment especially in primary patient-derived xenografts (PDXs) and transgenic xenografts. The anticancer mechanisms demonstrated by analyzing related downstream genes and discovering the targeted binding protein revealed that clofoctol exhibited the inhibition of GSCs by upregulation of Kruppel-like factor 13 (KLF13), a tumor suppressor gene, through clofoctol’s targeted binding protein, Upstream of N-ras (UNR). Collectively, these data demonstrated that induction of KLF13 expression suppressed growth of gliomas and provided a potential therapy for gliomas targeting GSCs. Importantly, our results also identified the RNA-binding protein UNR as a drug target.

     彭小忠研究员和韩为副研究员为本研究共同通讯作者，彭小忠课题组胡艳博士为本研究第一作者。本研究受到国家重点研发计划、国家自然科学基金和中国医学科学院医学与健康科技创新工程等资助。