Herb-sourced emodin inhibits angiogenesis of breast cancer by targeting VEGFA transcription
Herb-sourced emodin inhibits angiogenesis of breast cancer by targeting VEGFA transcription
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草药来源的大黄素通过靶向 VEGFA 转录抑制乳腺癌血管生成
DOI：
10.7150/thno.43622
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发表时间：
2020-01-01
期刊：
影响因子：
12.4
通讯作者：
Shi, Yi
中科院分区：
文献类型：
--
作者：
Zou, Gengyi;Zhang, Xiaotong;Shi, Yi
抗血管生成是癌症治疗中重要且有前途的策略。然而，目前使用针对 VEGFA 受体的抗血管内皮生长因子 A (VEGFA) 抗体或抑制剂的方法并不像预期的那么有效，部分原因是它们在体内阻断 VEGFA 信号传导的效率较低。迄今为止，仍然没有方法能够从源头上，即从转录水平有效阻断癌细胞中VEGFA的产生。在这里，我们的目标是找到阻断 VEGFA 转录的生物活性小分子。 方法：我们通过 MDA-MB-231 细胞系中基于细胞的筛选系统，筛选了包含 330 个源自中药的小分子的天然化合物库，以寻找激活丝氨酰-tRNA 合成酶 (SerRS) 表达的小分子，丝氨酰-tRNA 合成酶是一种新发现的有效的 VEGFA 转录抑制因子。首先在乳腺癌细胞中测试了候选分子调节 SerRS 和 VEGFA 表达的活性。接下来，我们通过测试候选药物对斑马鱼血管发育的影响以及通过小鼠基质胶塞血管生成测定来研究体内抗血管生成活性。我们进一步检查了候选药物在两种三阴性乳腺癌（TNBC）小鼠模型中的抗肿瘤活性。此外，还进行了链霉亲和素-生物素亲和力下拉试验、免疫共沉淀试验、对接分析和染色质免疫沉淀来鉴定候选药物的直接靶点。结果：我们鉴定出大黄素可以大大增加TNBC细胞中SerRS的表达，从而减少VEGFA的转录。大黄素能有效抑制斑马鱼的血管发育，并阻断携带TNBC的小鼠的肿瘤血管生成，从而大大提高存活率。我们还确定核受体辅阻遏物 2 (NCOR2) 是大黄素的直接靶点。一旦与大黄素结合，NCOR2就会从SerRS启动子上释放，导致SerRS表达激活，最终抑制VEGFA转录。结论：我们发现了一种源自草药的小分子大黄素，通过靶向转录调节因子NCOR2和SerRS抑制VEGFA转录和肿瘤血管生成，具有治疗TNBC的潜力。
Anti-angiogenesis is an important and promising strategy in cancer therapy. However, the current methods using anti-vascular endothelial growth factor A (VEGFA) antibodies or inhibitors targeting VEGFA receptors are not as efficient as expected partly due to their low efficiencies in blocking VEGFA signaling in vivo. Until now, there is still no method to effectively block VEGFA production in cancer cells from the very beginning, i.e., from the transcriptional level. Here, we aimed to find bioactive small molecules to block VEGFA transcription.Methods: We screened our natural compound pool containing 330 small molecules derived from Chinese traditional herbs for small molecules activating the expression of seryl-tRNA synthetase (SerRS), which is a newly identified potent transcriptional repressor of VEGFA, by a cell-based screening system in MDA-MB-231 cell line. The activities of the candidate molecules on regulating SerRS and VEGFA expression were first tested in breast cancer cells. We next investigated the antiangiogenic activity in vivo by testing the effects of candidate drugs on the vascular development in zebrafish and by matrigel plug angiogenesis assay in mice. We further examined the antitumor activities of candidate drugs in two triple-negative breast cancer (TNBC)-bearing mouse models. Furthermore, streptavidin-biotin affinity pull-down assay, coimmunoprecipitation assays, docking analysis and chromatin immunoprecipitation were performed to identify the direct targets of candidate drugs.Results: We identified emodin that could greatly increase SerRS expression in TNBC cells, consequently reducing VEGFA transcription. Emodin potently inhibited vascular development of zebrafish and blocked tumor angiogenesis in TNBC-bearing mice, greatly improving the survival. We also identified nuclear receptor corepressor 2 (NCOR2) to be the direct target of emodin. Once bound by emodin, NCOR2 got released from SerRS promoter, resulting in the activation of SerRS expression and eventually the suppression of VEGFA transcription.Conclusion: We discovered a herb-sourced small molecule emodin with the potential for the therapy of TNBC by targeting transcriptional regulators NCOR2 and SerRS to suppress VEGFA transcription and tumor angiogenesis.