环状RNA circ_0001589促进宫颈癌细胞生长的作用与机制研究

Rapid growth of cervical cancer cells is closely related to the poor prognosis of the cancer. So it is significant to inquiry the regulation mechanisms of the growth of cervical cancer cells. Recently, the effect of circular RNA on the regulation of cancer cell growth has been received much concern. However, it is unknown whether circular RNA is involved in the regulation of the growth of cervical cancer cells. Our preliminary study for the first time revealed that the circular RNA circ_0001589 could promote the growth of cervical cancer cells, and furthermore, we did pilot investigation on the corresponding mechanism and got several novel findings. Based on the innovative discoveries, together with previous reports, we hypothesize that circ_0001589 may elevate the levels of CDK6/Cyclin B1 by binding microRNA (miRNA) and release the miRNA-inhibited CDK6/Cyclin B1, which accelerates the progress of cell cycle and finally promotes the growth of cervical cancer cells. In this project, we will perform a series of experiments according to the hypothesis in order to leadingly illustrate the molecular mechanisms by which the pathway “circ_0001589-miRNA-CDK6/Cyclin B1” forms and circ_0001589 promotes the growth of cervical cancer cells. The expected results of this project may provide scientific evidences for developing novel anti-cervical cancer strategies targeted circ_0001589 and its mediated signaling pathway, and even for searching novel markers indicating the radiosensitivity/chemosensitivity or prognosis of cervical cancer.

宫颈癌细胞的快速生长与其不良预后密切相关，故探讨调控宫颈癌细胞生长的分子机制具有重要意义。近年有关环状RNA调控肿瘤细胞生长的功能倍受关注，但其是否参与调控宫颈癌细胞的生长，目前未见报道。我们在前期首次发现“环状RNA circ_0001589可促进宫颈癌细胞生长，并对相关机制进行探索且有进一步创新发现”的基础上，提出如下假设：circ_0001589可能通过吸附miRNA而解除miRNA对CDK6/Cyclin B1的抑制作用，从而加速细胞周期进程，促进宫颈癌细胞生长。本项目将围绕该假设开展一系列研究，旨在率先揭示“circ_0001589-miRNA-CDK6/Cyclin B1”通路形成的分子机制，阐明circ_0001589促宫颈癌细胞生长的分子机理，为探索以circ_0001589及其所介导的信号通路为靶标的抗宫颈癌新策略（乃至寻找判断其治疗敏感性和预后的新标志物）提供科学依据。

宫颈癌（cervical cancer，CC）是一种严重危害女性健康的生殖系统恶性肿瘤，CC细胞的快速增殖是其预后不良的重要因素。近年来，有关环状RNA调控CC细胞增殖的功能倍受关注。阐明环状RNA调控CC细胞增殖的具体分子机制，对于探索CC治疗的新策略具有重要意义。在本项目中，我们发现：（1）与对应癌旁组织相比，环状RNA circ_0001589的表达在CC组织中显著升高，且其高表达与患者的不良预后相关。同时，与正常宫颈上皮细胞株相比，circ_0001589在CC细胞系中的表达水平显著上调。circ_0001589主要定位于细胞质，并具有稳定的成环结构。（2）过表达circ_0001589可显著促进CC细胞增殖，加速细胞周期进程，促进CC细胞的侵袭与迁移；而敲降circ_0001589则可显著抑制CC细胞的增殖、侵袭与迁移。裸鼠荷瘤实验显示，circ_0001589可在体内显著促进CC移植瘤的生长。（3）在CC组织中，HuR蛋白的水平显著升高；同时随着CC的病理进展[从正常宫颈上皮到宫颈上皮内瘤变1级（CIN1），再到CIN2]，HuR蛋白的表达分布出现明显的从胞核向胞质转移。进一步研究发现，HuR蛋白可与circ_0001589相互作用，circ_0001589通过募集HuR蛋白而增强cyclinA/B和CDK1 mRNA的稳定性，进而加速CC细胞周期进程，促进CC细胞增殖。以上发现为探索以circ_0001589及其结合蛋白HuR为靶标的抗CC新策略提供了科学依据。.此外，我们还发现：（1）在CC细胞中，TRIM21可负性调控ATG4B蛋白的水平，并与ATG4B蛋白存在于同一复合体中。（2）TRIM21可通过下调ATG4B而抑制自噬，进而抑制CC细胞增殖。这些结果提示，“TRIM21-ATG4B通路”可能是宫颈癌治疗的潜在新靶点。