Purpose: Malignancy of cancer cells depends on the active transcription of tumor-associated genes. Recently, unique clusters of transcriptional enhancers, termed super-enhancers, have been reported to drive the expression of genes that define cell identity. In this study, we characterized specific super-enhancer–associated genes of osteosarcoma, and explored their potential therapeutic value. Experimental Design: Super-enhancer regions were characterized through chromatin immunoprecipitation sequencing (ChIP-seq). RT-qPCR was used to detect the mRNA level of CDK7 in patient specimens and confirm the regulation of sensitive oncogenes by THZ2. The phosphorylation of the initiation-associated sites of RNA polymerase II (RNAPII) C-terminal repeat domain (CTD) was measured using Western blotting. Microarray expression analysis was conducted to explore transcriptional changes after THZ2 treatment. A variety of in vitro and in vivo assays were performed to assess the effects of CDK7 knockdown and THZ2 treatment in osteosarcoma. Results: Super-enhancers were associated with oncogenic transcripts and key genes encoding cell-type–specific transcription factors in osteosarcoma. Knockdown of transcription factor CDK7 reduced phosphorylation of the RNAPII CTD, and suppressed the growth and metastasis of osteosarcoma. A new specific CDK7 inhibitor, THZ2, suppressed cancer biology by inhibition of transcriptional activity. Compared with typical enhancers, osteosarcoma super-enhancer–associated oncogenes were particular vulnerable to this transcriptional disruption. THZ2 exhibited a powerful anti-osteosarcoma effect in vitro and in vivo . Conclusions: Super-enhancer–associated genes contribute to the malignant potential of osteosarcoma, and selectively targeting super-enhancer–associated oncogenes with the specific CDK7 inhibitor THZ2 might be a promising therapeutic strategy for patients with osteosarcoma.

中文翻译：

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用共价 CDK7 抑制剂 THZ2 靶向骨肉瘤中与超级增强子相关的癌基因。

目的：癌细胞的恶性取决于肿瘤相关基因的活跃转录。最近，据报道，独特的转录增强子簇（称为超级增强子）可以驱动定义细胞身份的基因的表达。在这项研究中，我们表征了骨肉瘤的特定超增强子相关基因，并探讨了它们的潜在治疗价值。实验设计：通过染色质免疫沉淀测序（ChIP-seq）表征超级增强子区域。RT-qPCR 用于检测患者标本中 CDK7 的 mRNA 水平，并确认 THZ2 对敏感癌基因的调节。使用蛋白质印迹法测量 RNA 聚合酶 II (RNAPII) C 末端重复结构域 (CTD) 的起始相关位点的磷酸化。进行微阵列表达分析以探索 THZ2 处理后的转录变化。进行了各种体外和体内测定以评估 CDK7 敲低和 THZ2 治疗对骨肉瘤的影响。结果：超级增强子与骨肉瘤中的致癌转录物和编码细胞类型特异性转录因子的关键基因相关。转录因子 CDK7 的敲低降低了 RNAPII CTD 的磷酸化，并抑制了骨肉瘤的生长和转移。一种新的特异性 CDK7 抑制剂 THZ2 通过抑制转录活性来抑制癌症生物学。与典型的增强子相比，骨肉瘤超级增强子相关的癌基因特别容易受到这种转录破坏的影响。THZ2 在体外和体内表现出强大的抗骨肉瘤作用。