USF2介导的circACTN4通过调节原癌基因MYC的表达促进乳腺癌发生发展的机制研究

CircRNA与肿瘤发生发展密切相关，RNA结合蛋白可促进circRNA表达及结合circRNA调节基因转录，然而其调控机制仍不清楚。通过RNA-seq和qRT-PCR发现circACTN4在乳腺癌中高表达，双荧光素酶报告基因和Chip-qPCR证实ACTN4是USF2的靶基因，USF2的过表达增加了circACTN4的表达。RNA pull down和质谱显示circACTN4显著富集FUBP1。qRT-PCR证实circACTN4，FUBP1和MYC在癌组织中表达呈正相关。因此提出假说：USF2介导的circACTN4结合FUBP1增强了原癌基因MYC的表达，进而促进乳腺癌发生发展。拟进一步运用RIP、ChIP、EMSA、RNA pull down、功能获得与缺失等实验在细胞、动物与临床标本上揭示circACTN4发生和其促进乳腺癌发生发展的机制，旨为其作为临床新的靶点提供科学依据。

Recent studies have shown that circRNAs are closely related to the initiation and progression of cancers. RNA binding protein could promote circRNA expression and bind to circRNAs to regulate gene transcription. However, the underlying mechanism is still unclear. It was found that circACTN4 was up-regulated in breast cancer by RNA-seq and qRT-PCR. Dual luciferase reporter and Chip-qPCR assay suggest that ACTN4 is the target gene of transcription factor USF2. Up-regulated USF2 markedly increased expressions of circACTN4. RNA pull down and mass spectrometry showed that FUBP1 was significantly enriched by circACTN4. qRT-PCR and pearson correlation analysis showed that the level of circACTN4 were positively related with the expression of FUBP1 and MYC. Therefore, we hypothesized that circACTN4 mediated by USF2 could bind to FUBP1 to enhance the expression of MYC proto-oncogene, further to promote the initiation and progression of breast cancer. We intend to carry out RIP、ChIP、EMSA、RNA pull down and gain- and loss-of-function study at the level of cells, animals and clinical specimens to reveal the mechanisms of the biogenesis of circACTN4 and its promotion effect on the initiation and progression of breast cancer, so as to provide scientific basis for its use as a novel clinical target.