ΔNp63α通过调控circARHGAP5海绵吸附miRNA-942-3p抑制子宫颈癌细胞恶性行为的分子机制

Cervical cancer is still a serious disease that threatens women's reproductive health. The pathogenesis is closely related to the disorder of gene expression regulation. Recently, the role of non-coding RNA in tumorgenesis has become more and more important and needs to be improved. Our group found that one key member of p53 family, ΔNp63α (the core factor of differentiation and regulation) has a tumor suppressor function in cervical cancer cells. To clarify its mechanism, we sequenced and analyzed bioinformatics data by RNA-seq and ChIP-seq to acquire a cluster of circRNAs, and screened and confirmed that circARHGAP5 is a downstream regulatory RNA of ΔNp63α, which has the effect of inhibiting the proliferation of cervical cancer cells probably through sponge adsorption of miR-942-3p. In view of this, we have put forward a hypothesis that ΔNp63α inhibit cervical cancer cell malignant behaviors by regulation circARHGAP5 sponge adsorption of miRNA-942-3p. By exploring the molecular mechanism of the regulation of this gene axis in the malignant biology of cervical cancer cells, we can provide a strong theoretical basis for the finding the new targets for the treatment of cervical cancer. The function and molecular mechanism of circARHGAP5 have not been reported before.

子宫颈癌依然是严重威胁女性生殖健康的重大疾病，其发病机制与基因表达调控机制紊乱密切相关，近年来非编码RNA在肿瘤发病机制中的作用日益重视，亟待完善。本课题组前期发现p53家族重要成员分化调控关键因子ΔNp63α在宫颈癌细胞中具有抑癌功能，为阐明其机制，我们通过RNA-seq及ChIP-seq 测序并分析生物信息学数据，挖掘出一组circRNAs，筛选并确证circARHGAP5为ΔNp63α下游调控RNA，具有抑制宫颈癌细胞的增殖的作用，其机制可能通过海绵吸附miR-942-3p发挥作用。鉴于此，我们提出：ΔNp63α通过调控 circARHGAP5海绵吸附miRNA-942-3p抑制子宫颈癌细胞恶性行为的分子机制的假说。解析该基因轴在子宫颈癌细胞恶性生物学的调控分子机制，将为探寻其用于子宫颈癌治疗的新靶点提供有力的理论依据。circARHGAP5的功能及分子机制研究尚未见相关报道。

子宫颈癌在全球女性的癌症发病率中位居第四，其死亡率在很多发展中国家位居第一，严重威胁女性健康。早期宫颈癌患者经手术治疗预后较好，但局部晚期患者或复发患者就诊时已失去最佳的手术时机，尽管随着靶向药物的逐渐问世，以铂类为基础的联合放化疗仍是临床上主要的治疗方案。因此，一旦发生铂耐药，患者的整体预后较差。鉴于此，解析子宫颈癌发生铂耐药的分子机制有望为消除子宫颈癌提供更坚实的理论依据。circRNAs作为非编码RNA的一种，可通过多种作用机制在肿瘤的进展中发挥着关键的作用，包括介导肿瘤细胞的铂耐药。在本研究中，前期实验发现ΔNp63α在子宫颈癌中发挥抑制铂耐药的功能，且ΔNp63α可正向调控circARHGAP5。因此，我们进一步通过成环验证检测及Fish等实验确定circARHGAP5位于细胞质中。并且，与正常宫颈组织和初始手术切除的宫颈癌组织相比，circARHGAP5表达量在顺铂耐药的宫颈癌组织中下调。在功能上，体内及体外实验表明，circARHGAP5可抑制顺铂介导的子宫颈鳞癌细胞凋亡。在机制上，我们发现circARHGAP5与RNA结合蛋白AUF1相互作用，并验证了二者的结合位点。同时，AUF1过表达可抑制顺铂介导的细胞凋亡。此外，我们预测并验证AUF1下游与凋亡途径相关的靶基因，发现AUF1可负向调控促凋亡基因Bim的表达，且Bim的表达受circARHGAP5的正向调控，根据AUF1作为RBP对下游mRNA潜在的调控机制，推测circARHGAP5通过与AUF1结合抑制AUF1对BIM mRNA的降解进而促进了铂类药物诱导的肿瘤细胞的凋亡。综上，本研究表明，circARHGAP5与AUF1结合并阻止AUF1与BIM mRNA相互作用，该过程在抑制子宫颈鳞状细胞癌发生顺铂药物诱导的耐药中发挥了关键作用，为攻克顺铂耐药奠定理论基础。