淋巴结转移与乳腺癌的预后密切相关，术前对腋窝淋巴结转移进行有效预测是乳腺癌治疗方案选择的关键，也是临床亟待解决的难题。研究发现肿瘤细胞来源非编码RNA可通过外泌体传递参与淋巴结转移的调控，并能够在血清中稳定存在，有望成为新型肿瘤标志物。本课题前期发现环状RNA circ_0067842在腋窝淋巴结阳性的乳腺癌组织中显著上调。进一步研究显示乳腺癌细胞中circ_0067842通过与hnRNPA2B1结合被特异性包裹入外泌体并传递至内皮细胞，促进淋巴管生成。现拟通过体内/外实验明确circ_0067842在乳腺癌淋巴结转移中的作用；揭示circ_0067842通过外泌体传递至内皮细胞并促进淋巴管生成的分子机制；最后基于微滴式数字PCR检测评估血清外泌体circ_0067842对腋窝淋巴结转移预测的临床应用价值。本研究不仅有助于发现乳腺癌转移新机制，也将为术前腋窝淋巴结转移有效预测提供新的途径。

Lymph node metastasis is closely related to the prognosis of breast cancer. Preoperative prediction of axillary lymph node metastasis is pivotal to guide therapeutic intervention of breast cancer. However, it is difficult to be achieved due to the lack of effective prediction methods. It has been reported that non-coding RNA derived from tumor cells can be transferred by exosomes to regulate lymph node metastasis. They stably exist in serum, and are potential novel predictors for tumor metastasis. In our previous studies, we found that circ_0067842 was significantly up-regulated in breast cancer tissues from patients with axillary lymph node metastasis. Circ_0067842 derived from breast cancer cells was found to be encapsulated into exosomes by binding to hnRNPA2B1, and taken up by lymphatic endothelial cells to promote lymphangiogenesis. Based on the preliminary data, we intend to further investigate the role of exosomal circ_0067842 in lymph node metastasis of breast cancer in vitro and in vivo, and then explore the molecular mechanism by which exosomes take up circ_0067842 and transfer it to endothelial cells to promote lymphangiogenesis. Moreover, the clinical value of serum exosomal circ_0067842 in predicting axillary lymph node metastasis of breast cancer will be evaluated by using droplet digital PCR. This study will provide new insights into the mechanism of breast cancer metastasis and identify novel biomarkers for preoperative prediction of axillary lymph node metastasis in breast cancer.