环状RNAcirc_0000567具有靶向结合miR-4667-5p及Hsp90蛋白的双重功能及其在抑制结直肠癌生长及转移中的作用机制研究

Colorectal cancer (CRC) has high morbidity and mortality. It lacks sensitive and specific diagnostic markers and therapeutic targets. Circular RNAs (circRNAs) play crucial regulatory roles in colorectal cancer and are expected to be new targets for diagnosis and treantment. However, the mechanism is still unclear. In our previous work, we found a circRNA circ_0000567 significantly down-regulated in colorectal cancer tissues and cells. Functional assays indicated that circ_0000567 could inhibit CRC cell growth and metastasis. Through the transcriptome sequencing and preliminary experiments, we found that circ_0000567 could negatively regulate the PI3K/Akt pathway and bind miR-4667-5p and Hsp90 proteins, and miR-4667-5p could target PTEN. PTEN and Hsp90 are the key proteins that regulate Akt phosphorylation and ubiquitin-dependent degradation. In the current project, we intend to further clarify the function and clinical signifiance of circ_0000567, and investigate the molecular mechanism of circ_0000567 inhibiting colorectal cancer growth and metastasis by modulating PI3K/Akt pathway via target binding miR-4667-5p and Hsp90 proteins through performing FISH, RIP, CoIP and CLIP assays. The study will provide a new approach for the diagnosis and treatment of colorectal cancer.

结直肠癌发病率及死亡率高，缺少敏感、特异的诊断标志物及治疗靶点。环状RNA在结直肠癌中发挥重要的调控作用，有望成为新型的诊疗靶标，但是作用机制尚不清楚。我们前期发现环状RNAcirc_0000567在结直肠癌组织和细胞中表达明显下调，功能实验显示其能抑制结直肠癌细胞的生长及转移。通过转录组测序及初步的实验发现circ_0000567负调控PI3K/Akt通路，并靶向结合miR-4667-5p及Hsp90蛋白，miR-4667-5p靶向PTEN，而PTEN和Hsp90是调控Akt磷酸化及泛素依赖性降解的关键蛋白。因此本项目拟进一步明确circ_0000567的功能及临床价值，并通过FISH、RIP、CoIP及CLIP等实验阐明circ_0000567通过靶向结合miR-4667-5p及Hsp90蛋白调控PI3K/Akt通路抑制结直肠癌生长及转移的机制，为结直肠癌的诊断及治疗开辟新的途径。

结直肠癌是常见的恶性肿瘤之一，近年来发现环状RNA在结直肠癌恶性进展中发挥重要作用，有可能作为诊疗靶点。前期发现环状RNAcirc_0000567在结直肠癌高通量测序数据中表达下调，通过RT-qPCR验证了circ_0000567在结直肠癌组织和细胞株中表达下调，且低表达与肿瘤大小和转移正相关。体外实验发现下调circ_0000567表达促进结直肠癌细胞的增殖及迁移，而过表达circ_0000567则抑制了细胞的增殖和迁移，体内实验也表明下调circ_0000567表达促进结直肠癌细胞在体内的生长和转移。通过转录组测序、双荧光素酶实验、RNA pulldown、质谱、RIP等表明circ_0000567可以靶向结合miR-4667-5p及Hsp90蛋白，从而上调miR-4667-5p的靶基因PTEN的表达，抑制Akt的磷酸化，另一方面通过竞争性结合Hsp90促进Akt的降解，因此本项目揭示了circ_0000567通过与miRNA和蛋白结合抑制结直肠癌生长及转移的新机制。本项目为阐明结直肠癌恶性进展的机制以及临床诊疗提供新的思路和靶标。