外泌体介导环状RNA调控肝癌索拉菲尼耐药机制

Sorafenib, a multi-target tyrosine kinase inhibitor, is so far the only first-line targeted therapy for hepatocellular carcinoma (HCC). Concerns had been raised for its unstable efficacy and resistance in HCC, in which epigenetic factors play important roles. However, difficulties such as minor efficacy, instability and off-target effect retard us from fighting sorafenib resistance. Circular RNA (circRNA) is a type of stable non-coding RNA that could act as competing endogenous RNA (ceRNA) to sponge multiple micro RNAs (miRNAs), which makes it more specific and potent than miRNA. By microarray screening of established sorafenib resistant HCC cell lines, our research group identified the circRNA_103420, which could be increased by sorafenib treatment, promote sorafenib resistance and even be transmitted to sensitive HCC cells to spread the resistance. We also found that circRNA_103420 could competitively sponge miR-345-5p, miR-26b-5p and miR-26a-5p to modulate their downstream signals and eventually promote sorafenib multi-target resistance. It is promising that circRNA_103420 could a novel target for HCC therapeutics, providing inspiration and theoretical foundation for HCC treatment.

多靶点酪氨酸激酶抑制剂索拉菲尼是肝癌临床唯一的一线靶向药物，近年来耐药现象日益突出，表观因素是肿瘤耐药的关键因素，但微效、不稳定及脱靶效应是克服耐药的难点。环状RNA（circRNA）是一类结构稳定的非编码RNA，其可通过海绵效应竞争性结合多个微小RNA （miRNA），其作用较miRNA更加特异而强效。课题组前期通过筛选并经临床验证，发现索拉菲尼治疗肝癌可使circRNA_103420水平增加，外泌体可将其从耐药细胞转运到敏感细胞使其获得耐药性，继而竞争性地吸引miR-345-5p，miR-26b-5p和miR-26a-5p进而影响下游通路，最终促进肝癌对索拉菲尼的多靶点耐药 。circRNA_103420有望成为肝癌索拉菲尼合并治疗的新靶点，为未来肝癌的治疗提供新的思路和理论依据。

索拉非尼是治疗晚期肝细胞癌的一线化疗药物。然而，索拉非尼耐药严重限制了其临床治疗效果，而其耐药机制尚也未完全阐明。在对circRNA_103420的研究中，我们发现circRNA-103420在索拉非尼耐药的HCC细胞中表达上调，而敲减circRNA-103420显著提高了索拉非尼的细胞杀伤能力。进一步研究表明，circRNA-103420可以通过ceRNA机制结合miR-345-5p，通过miRNA sponge机制促进转录因子SP1与DCBLD2的相互作用，通过稳定DCBLD2，发挥作用。HCC小鼠动物实验发现注射siRNA沉默circRNA-103420可以显著增强索拉非尼对HCC的药物杀伤作用。.在对circRNA_104797（circRNA-SORE）的研究中，我们发现，circRNA-SORE在索拉非尼耐药的HCC细胞中表达上调，而敲减circRNA-SORE显著提高了索拉非尼的细胞杀伤能力。进一步研究表明，circRNA-SORE在胞质中可与蛋白YBX1结合，阻止YBX1核与E3泛素连接酶PRP19的相互作用，从而阻断PRP19介导的YBX1降解，通过稳定YBX1，发挥作用。此外，体外和体内研究结果表明，circRNA-SORE通过外泌体转运，在HCC细胞中传播索拉非尼耐药性。HCC小鼠动物实验发现注射siRNA沉默circRNA-SORE可以显著增强索拉非尼对HCC的药物杀伤作用。此外，研究还发现circRNA-SORE可以通过作为miRNA sponge机制来隔离miR-103a-2-5p和miR-660-3p，从而竞争性地激活Wnt/β-catenin通路并诱导索拉非尼耐药性。进一步研究发现，耐药细胞中circRNA-SORE水平的增加是由于RNA稳定性的增加。而RNA稳定性受到circRNA-SORE上特定位点的m6A修饰的影响。动物实验中，采用慢病毒敲减circRNA-SORE可以显著提高了索拉非尼在动物模型中的疗效。.研究结果提示circRNA-103420及circRNA_104797在索拉非尼耐药过程中扮演重要角色，可作为临床药物治疗新靶点，为提高肝癌临床药物疗效提供新思路。.相关研究内容已发表2篇论文。