长链非编码RNA-Lnc-712基因扩增诱导三阴性乳腺癌转移的作用及分子机制研究

Breast cancer with triple negative phenotype (TNBC) are characterized by the absence of the estrogen receptor alpha (ER-a), the progesterone receptor (PgR), and the human epidermal growth factor receptor-2 (HER-2) expression. The characteristics of TNBC are prone to recurrence, distant metastasis and poor clinical prognosis. Identification of key long non-coding RNA and elucidating the mechanism in metastasis would be of great value for TNBC diagnosis and therapy. Recently, using TCGA copy number amplification data and lncRNA chips data, we found that lncRNA-712 is one of the most significantly upregulated lncRNA in TNBC with lymph node metastasis. Furthermore, we demonstrated that lncRNA-712 promotes TNBC cell proliferation, migration and invasion, and autophagy. Then, protein chips and RNA immunoprecipitation assay revealed that lncRNA-712 interacted with autophagy associated protein USP14 and VPS34. Moreover, we observed that lncRNA-712 can be secreted out of tumor cells by exosome, and promoted normal mammary epithelial cells autophagy. In the current project, we aim to explore the biological roles and underlying mechanisms in which lncRNA-712 promotes TNBC metastasis via exosomes and autophagy, which will provide new biomarkers and targets for the diagnosis and treatment for TNBC.

三阴性乳腺癌易早期复发、远处转移、预后差、尚无针对性标准治疗方案，寻找其关键的调控长链非编码RNA(lncRNA)，阐明其功能和分子机制，对三阴性乳腺癌的诊治有重要意义。我们前期通过TCGA拷贝数扩增数据和lncRNA芯片筛选到在三阴性乳腺癌中表达显著上调、且其表达水平与三阴性乳腺癌淋巴结转移、不良预后正相关的lncRNA-712。进一步发现：①lncRNA-712可诱导三阴性乳腺癌恶性表型的形成、自噬的发生；②lncRNA-712能够与自噬脂酶VPS34、去泛素化酶USP14（调控自噬蛋白Beclin1）结合；③lncRNA-712可被外泌体包裹分泌至肿瘤细胞外，促进正常乳腺上皮细胞发生自噬。在此基础上，本项目将利用多种技术和方法深层次解析lncRNA-712通过自噬诱导三阴性乳腺癌转移的分子机制，并结合临床数据分析和PDX模型，探讨lncRNA-712在三阴性乳腺癌临床诊治的意义。

本课题组前期通过TCGA拷贝数扩增数据结合lncRNA芯片筛选得到在三阴性乳腺癌中表达显著上调、且其表达水平与三阴性乳腺癌淋巴结转移、不良预后正相关的lncRNA-712。进一步发现，lncRNA-712可诱导三阴性乳腺癌恶性表型的形成、自噬的发生；lncRNA-712能够与自噬脂酶VPS34、去泛素化酶USP14（调控自噬蛋白Beclin1）结合；lncRNA-712可被外泌体包裹分泌至肿瘤细胞外，促进正常乳腺上皮细胞发生自噬。因此，我们推测在肿瘤细胞中，lncRNA-712通过结合VPS34和USP14促进细胞自噬，减少细胞的失巢凋亡，提高肿瘤细胞的转移能力；lncRNA-712可被外泌体包裹分泌至肿瘤细胞周围的正常细胞，在正常乳腺上皮细胞中，lncRNA-712 通过结合 VPS34 和 USP14 促进细胞自噬，蛋白降解成氨基酸，为肿瘤细胞的生长、转移提供原材料和能量。本课题以上述假设为研究内容，发现lncRNA-712可延长USP14蛋白的半衰期正调控其表达水平，可促进VSP34乙酰化增强其脂酶活性；利用FDA批准的“老药库”筛选针对lncRNA-712 的“老药”并通过乳腺癌类器官研究该“老药”对三阴性乳腺癌的治疗效果。本研究不但为三阴性乳腺癌发生发展机制研究拓宽新思路，也为三阴性乳腺癌治疗提供新策略。