Disruption of super-enhancer-driven tumor suppressor gene RCAN1.4 expression promotes the malignancy of breast carcinoma
Disruption of super-enhancer-driven tumor suppressor gene RCAN1.4 expression promotes the malignancy of breast carcinoma
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超级增强子驱动的抑癌基因RCAN1.4表达的破坏促进乳腺癌的恶性
DOI：
10.1186/s12943-020-01236-z
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发表时间：
2020-08-08
期刊：
影响因子：
37.3
通讯作者：
Tang, Jun
中科院分区：
文献类型：
--
作者：
Deng, Rong;Huang, Jun-Hao;Tang, Jun
背景：超增强子（SE）在肿瘤中起着重要作用，常与癌基因的激活有关。然而，关于SE如何促进肿瘤抑制知之甚少。唐氏综合征患者乳腺癌（BC）的发病率显着降低，从而推动了对人类21号染色体（HSA 21）上肿瘤抑制基因的研究。在这项研究中，我们的目的是确定和探索的潜在机制，建立肿瘤抑制因子RCAN1.4对HSA 21在BC。方法：在硅片分析和免疫组化染色，以评估表达和临床意义的RCAN1.4和RUNX 3在BC。通过体外和体内实验研究RCAN1.4对乳腺癌恶性程度的影响。利用ChIP-seq数据分析、ChIP-qPCR、双CRISPR基因组编辑和荧光素酶报告基因测定来确认RUNX 3参与调控BC中的RCAN1.4相关SE。RCAN1.4和RUNX 3共表达的临床价值进行了评估在BC patients.Results：在这里，我们的特点是RCAN1.4作为一个潜在的肿瘤抑制在BC。RCAN1.4缺失促进肿瘤向骨和脑转移，其过表达通过阻断钙调神经磷酸酶-NFATc 1通路抑制肿瘤生长。出乎意料的是，我们发现RCAN1.4的表达是由一个类似于23 kb长的SE驱动的。RCAN1.4-SEdistal对BRD 4抑制敏感，其缺失可使RCAN1.4表达降低90%以上，并诱导BC细胞恶性表型。我们还发现RCAN1.4的SE区域中的结合位点富集了转录因子RUNX 3的共有序列。RUNX 3的敲低抑制了荧光素酶活性，并且还降低了RCAN1.4的SE区域处的H3 K27 ac富集结合。此外，由RUNX 3缺失介导的SE驱动的RCAN1.4表达异常可能在BC患者中具有生理学意义和临床相关性。值得注意的是，我们建立了一个预后模型的基础上RCAN1.4和RUNX 3的共同表达，有效地预测了总生存率在BC patients.Conclusions：这些研究结果揭示了一个重要的作用，SE在促进肿瘤抑制在BC。考虑到RCAN1.4和RUNX 3低表达的组合预后较差，RUNX 3-RCAN1.4轴可能是BC患者的新的预后生物标志物和治疗靶点。
Background: Super-enhancers (SEs) play a crucial role in cancer, which is often associate with activated oncogenes. However, little is known about how SEs facilitate tumour suppression. Individuals with Down syndrome exhibit a remarkably reduced incidence of breast cancer (BC), moving the search for tumor suppressor genes on human chromosome 21 (HSA21). In this study, we aim to identify and explore potential mechanisms by which SEs are established for tumor suppressor RCAN1.4 on HSA21 in BC.Methods: In silico analysis and immunohistochemical staining were used to assess the expression and clinical relevance of RCAN1.4 and RUNX3 in BC. Function experiments were performed to evaluate the effects of RCAN1.4 on the malignancy of breast carcinoma in vitro and in vivo. ChIP-seq data analysis, ChIP-qPCR, double-CRISPR genome editing, and luciferase reporter assay were utilized to confirm RUNX3 was involved in regulating RCAN1.4-associated SE in BC. The clinical value of co-expression of RCAN1.4 and RUNX3 was evaluated in BC patients.Results: Here, we characterized RCAN1.4 as a potential tumour suppressor in BC. RCAN1.4 loss promoted tumour metastasis to bone and brain, and its overexpression inhibited tumour growth by blocking the calcineurin-NFATc1 pathway. Unexpectedly, we found RCAN1.4 expression was driven by a similar to 23 kb-long SE. RCAN1.4-SEdistal was sensitive to BRD4 inhibition, and its deletion decreased RCAN1.4 expression by over 90% and induced the malignant phenotype of BC cells. We also discovered that the binding sites in the SE region of RCAN1.4 were enriched for consensus sequences of transcription factor RUNX3. Knockdown of RUNX3 repressed the luciferase activity and also decreased H3K27ac enrichment binding at the SE region of RCAN1.4. Furthermore, abnormal SE-driven RCAN1.4 expression mediated by RUNX3 loss could be physiologically significant and clinically relevant in BC patients. Notably, we established a prognostic model based on RCAN1.4 and RUNX3 co-expression that effectively predicted the overall survival in BC patients.Conclusions: These findings reveal an important role of SEs in facilitating tumour suppression in BC. Considering that the combination of low RCAN1.4 and low RUNX3 expression has worse prognosis, RUNX3-RCAN1.4 axis maybe a novel prognostic biomarker and therapeutic target for BC patients.