lncRNA-FAM172A-2:1作为ceRNA在IL-8诱导的乳腺癌细胞上皮间质转化过程中的作用机制研究

Epithelial-mesenchymal transition (EMT) is a key process of tumor invasion and metastasis. Non-coding RNAs (nc-RNAs) including miRNA and lncRNA also play crucial roles in many biological and pathological processes, including EMT. Some lncRNAs play important roles in the regulation of gene expression by acting as competing endogenous RNAs (ceRNAs). Transcription factors of the ZEB protein family (ZEB1 and ZEB2) and several microRNA species (predominantly miR-200 family members) form a double negative feedback loop, which controls EMT and MET programs in both development and tumorigenesis. Our initial experiments utilizing lncRNA microarray and related bioinformatics analysis find the lnc-FAM172A-2:1 which may function as a ceRNA of miR-200 family in the process of IL-8 induced breast cancer cell EMT. We also found that inhibition of lnc-FAM172A-2:1 reverse breast cancer cell EMT, but its function and mechanism need to be further elucidated. Therefore, our research focus on breast cancer cell and animal model propose to confirm the function of lnc-FAM172A-2:1 in the process of breast cancer cell EMT induced by IL-8 and further validate that lnc-FAM172A-2:1 which is up-regulated by IL-8 work as a ceRNA of miR-200 family to inhibit the degradation of ZEB and then promotes breast cancer cell EMT.

上皮间质转化（EMT）是肿瘤发生转移的先决条件。miRNA、lncRNA等非编码RNA参与EMT的发生。ZEB蛋白作为EMT中的核心因素，miR-200家族与其形成双重负性调节通路，调控肿瘤的EMT。LncRNA作为竞争性内源RNA（ceRNA）与miRNA结合抑制miRNA的表达，从而减弱对mRNA的直接影响。前期我们利用芯片及生物信息学分析发现，lnc-FAM172A-2:1在IL-8诱导的乳腺癌细胞EMT过程中可能与miR-200家族互为ceRNA，上调lnc-FAM172A-2:1能够促进乳腺癌细胞发生EMT，但其作用机制尚待研究。本研究拟在乳腺癌细胞和动物模型中证实lnc-FAM172A-2:1在IL-8诱导的乳腺癌细胞EMT中的作用，并进一步验证IL-8诱导lnc-FAM172A-2:1上调，后者作为miR-200家族的ceRNA，阻止ZEB降解，从而促进乳腺癌细胞发生EMT。

上皮间质转化（EMT）是肿瘤发生转移的先决条件。miRNA、lncRNA等非编码RNA参与EMT的发生。ZEB蛋白作为EMT中的核心因素，miR-200家族与其形成双重负性调节通路，调控肿瘤的EMT。LncRNA作为竞争性内源RNA（ceRNA）与miRNA结合抑制miRNA的表达，从而减弱对mRNA的直接影响。IL-8通过下调乳腺癌细胞内miRNA-200家族的表达促进乳腺癌细胞发生侵袭和迁移，从而促进乳腺癌细胞发生EMT。MCF-7过表达IL-8后，利用lncRNA芯片及生物信息学分析发现，lncRNA NR2F1-AS1在IL-8诱导的乳腺癌细胞EMT过程中发挥重要作用，IL-8和lncRNA NR2F1-AS1表达成正相关，上调IL-8的表达，lncRNA NR2F1-AS1表达上调，同时乳腺癌细胞侵袭和迁移能力增强。同时，我们研究发现，在乳腺癌中，lncRNA NR2F1-AS1与CD31和CD34表达成正相关，人脐静脉内皮细胞（HUVEC）转染lncRNA NR2F1-AS1后小管形成能力增加。人乳腺癌细胞过表达lncRNA NR2F1-AS1后促进HUVEC增殖、小管形成和迁移能力。在斑马鱼模型模型中，lncRNA NR2F1-AS1促进肿瘤新生血管形成进而促进乳腺癌细胞转移。在小鼠模型中lncRNA NR2F1-AS1促进肿瘤血管形成，增加微血管密度和促进肿瘤生长。ncRNA NR2F1-AS1通过与miRNA-388-3p相互作用增加IGF-1表达，从而激活IGF-1R和ERK通路促进乳腺癌细胞血管生成。上述研究为乳腺癌的发生发展提供了新的研究方向，同时为寻找乳腺癌新的治疗靶点提供了理论依据。