Triple-negative breast cancer (TNBC) is the most malignant subtype of breast cancer with highly invasive ability and metastatic nature to the lymph nodes. Long non-coding RNAs (lncRNAs) have been widely explored in cancer tumorigenesis and progression. However, their roles in TNBC lymph node metastasis remains rarely studied. The expression of lncRNA highly upregulated in metastatic TNBC (HUMT) in cell lines and tissues was detected by quantitative real-time PCR (qRT-PCR) and in situ hybridization (ISH). RNA immunoprecipitation (RIP) and RNA pulldown were used to verify the interaction between lncRNA and protein. Chromatin immunoprecipitation (CHIP) and dCas9-gRNA-guided chromatin immunoprecipitation (dCas9-CHIP) were conducted to identify the specific binding site of HUMT-YBX1 complex. Western blot was used to detect the downstream of HUMT. HUMT was significantly upregulated in lymph node invasive cells and predicted poorer clinical prognosis. Functional study indicated that HUMT promoted lymphangiogenesis and lymph node metastasis. Bioinformatic analysis and qRT-PCR showed that the high expression of HUMT was correlated with the hypomethylation status of its promoter region. Further, HUMT recruited Y-box binding protein 1 (YBX1) to form a novel transcription complex and activated the expression of forkhead box k1 (FOXK1), thus enhancing the expression of vascular endothelial growth factor C (VEGFC). The therapeutic value was further validated in patient-derived xenograft (PDX) models, and a combined marker panel exhibited a better prognostic value for TNBC in receiver operating characteristic (ROC) analysis. Our study identified a novel TNBC lymph node metastasis-associated lncRNA, which promoted TNBC progression and indicated a novel biomarker and potential therapeutic target for TNBC lymph node metastasis.

中文翻译：

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长的非编码RNA HUMT低甲基化通过激活三阴性乳腺癌中的FOXK1转录促进淋巴管生成和转移。

三阴性乳腺癌（TNBC）是乳腺癌的最恶性亚型，具有高度浸润性和对淋巴结转移的特性。长非编码RNA（lncRNA）在癌症的发生和发展中已被广泛研究。然而，它们在TNBC淋巴结转移中的作用仍然很少研究。通过实时定量PCR（qRT-PCR）和原位杂交（ISH）检测在细胞系和组织中转移性TNBC（HUMT）中上调的lncRNA的表达。RNA免疫沉淀（RIP）和RNA下拉用于验证lncRNA与蛋白质之间的相互作用。进行染色质免疫沉淀（CHIP）和dCas9-gRNA引导的染色质免疫沉淀（dCas9-CHIP），以鉴定HUMT-YBX1复合物的特异性结合位点。Western印迹用于检测HUMT的下游。HUMT在淋巴结浸润细胞中显着上调，并预测较差的临床预后。功能研究表明，HUMT促进淋巴管生成和淋巴结转移。生物信息学分析和qRT-PCR表明，HUMT的高表达与其启动子区域的低甲基化状态有关。此外，HUMT募集了Y-box结合蛋白1（YBX1）以形成新的转录复合物并激活了叉头盒k1（FOXK1）的表达，从而增强了血管内皮生长因子C（VEGFC）的表达。在患者来源的异种移植（PDX）模型中进一步验证了治疗价值，并且组合标记物组在接受者操作特征（ROC）分析中显示出更好的TNBC预后价值。我们的研究确定了一种新的TNBC淋巴结转移相关的lncRNA，