WNT11/ROR2 signaling is associated with tumor invasion and poor survival in breast cancer [patients]

Breast cancer is the most common cancer in women with more than two million new cases diagnosed in 2018. Patients frequently develop metastases in the course of their disease which limit survival due to the lack of a curative treatment. One signaling pathway that is frequently involved in cancer initiation and progression is the WNT pathway. Breast cancer has been associated with activation of the WNT signaling pathway, although the underlying molecular mechanisms are still unclear. Here, we found the WNT receptor ROR2 to be highly expressed in aggressive breast tumors and associated with worse metastasis-free survival. In this study we addressed this question and demonstrated for the first time that WNT11 is a novel ligand for ROR2 in humans. WNT11 binds to the CRD of ROR2 and mediates WNT/PCP signaling via the RHO/ROCK pathway that confers an aggressive phenotype to breast cancer cells. ROR2 and WNT11 are both highly expressed in human brain metastases and linked with short patient survival. Overall design: We collected samples from 31 patients with brain metastases and characterized them by RNA-Seq. With the obtained data, we performed a gene enrichment analysis looking at three different gene sets, either associated with canonical, non-canonical, or regulation of WNT signaling. Next, we isolated RNA from seven metastases as well as normal brain tissue and analysed the expression of ROR2 and its ligand WNT11 by quantitative real-time PCR. To confirm the role of ROR2/WNT11 in metastasis, we correlated the expression levels of ROR2 and WNT11 in the metastatic tissue with patient outcome using the gene expression data obtained by RNA-Seq.

乳腺癌是女性最常见的恶性肿瘤，2018年全球新增确诊病例超200万例。患者在病程中常发生肿瘤转移，由于缺乏治愈性治疗手段，转移灶会显著缩短患者的生存期。WNT信号通路（WNT signaling pathway）是频繁参与肿瘤发生与进展的关键信号通路之一。尽管具体分子机制尚未阐明，但已有研究证实乳腺癌与WNT信号通路的激活密切相关。

本研究发现，WNT受体ROR2在侵袭性乳腺肿瘤中呈高表达，且与较差的无转移生存期显著相关。本研究针对该科学问题展开系统探索，并首次证实：在人类机体中，WNT11是ROR2的新型配体。WNT11可结合ROR2的半胱氨酸富集结构域（cysteine-rich domain, CRD），并通过RHO/ROCK通路介导WNT/平面细胞极性（planar cell polarity, PCP）信号转导，进而赋予乳腺癌细胞侵袭性表型。ROR2与WNT11在人类脑转移灶中均呈高表达，且与患者生存期缩短存在显著关联。

整体实验设计：我们收集了31例脑转移患者的临床样本，并通过RNA测序（RNA-Seq）对样本进行转录组表征。基于获取的转录组数据，我们针对三类不同的基因集开展基因富集分析，这三类基因集分别与经典WNT信号通路、非经典WNT信号通路以及WNT信号通路调控相关。随后，我们从7例转移灶组织及正常脑组织中提取总RNA，并通过实时定量聚合酶链反应（quantitative real-time PCR）分析ROR2及其配体WNT11的表达水平。为验证ROR2/WNT11信号轴在肿瘤转移中的功能作用，我们利用RNA测序获得的基因表达数据，将转移组织中ROR2与WNT11的表达水平与患者临床预后进行关联分析。