长链非编码RNA–DANCR驱动卵巢癌细胞铂抵抗的作用与机制研究

Ovarian cancer is the most deadly gynecological cancer; chemotherapy resistance is an urgent need to solve an important clinical problem. Recent studies have shown that long noncoding RNA (lncRNA) may be associated with the prognosis of ovarian cancer, tumor occurrence and progression. Our team newly discovered that lncRNA DANCR not only highly expressed in ovarian cancer tissues, but also is significantly up-regulated by chemosensitizers cisplatin and paclitaxel. Further studies have shown that knockdown of DANCR can inhibit ovarian cancer cell drug resistance; this effect may be act through the regulation of miR-513a-5p and RAS-MAPK signaling pathway related gene expression. Based on the findings, we put forward a novel hypothesis that "lncRNA DANCR may promote ovarian cancer drug resistance through the miR-513a-5p/RAS-MAPK signal axis". We intend to make use of technical means such as clinical specimen, cytology and animal model to clarify the relationship between lncRNA DANCR and the malignant degree and recurrence of ovarian cancer, and to discover the molecular mechanism of lncRNA DANCR in promotion of the proliferation, metastasis and platinum resistance of ovarian cancer, and to explore a novel intervention strategy against ovarian cancer drug resistance based on the exosome delivery system. The successful implementation of the project is expected to provide new ideas for the detection of ovarian cancer targets, drug resistance mechanisms and treatment strategies.

卵巢癌是最致命的妇科癌症，化疗耐药是急需解决的重要临床难题。近年研究显示, 长链非编码RNA(lncRNA)可能与卵巢癌的预后、肿瘤的发生和发展密切相关。我们团队新发现lncRNA DANCR分子不仅高表达卵巢癌组织中，而且化疗药物顺铂和紫杉醇显著诱导DANCR表达上调。进一步研究证明，下调DANCR可抑制卵巢癌细胞的耐药性；这种作用是通过调控miR-513a-5p和RAS-MAPK信号通路相关基因的表达实现的。基于此，本项目申请提出“DANCR分子可能通过miR-513a-5p/RAS-MAPK信号轴促进卵巢癌顺铂耐药”的科学假设。我们拟借助临床标本、细胞学和动物模型等技术手段，明确DANCR分子与卵巢癌恶性程度、复发的关系及促进卵巢癌增殖、转移和铂抵抗的作用机制，并探索基于外泌体递送系统的卵巢癌耐药的干预策略。该项目的成功实施，有望为卵巢癌的检测靶点、耐药机制和治疗策略等提供新思路。

卵巢癌发病率和死亡率居高不下，亟需探寻新型有效的治疗靶点，以改善患者预后。泛素特异性蛋白酶33 (USP33)是USP家族中的一种去泛素化酶，是肿瘤发生的关键调节蛋白。然而，其在卵巢癌中的应用价值及相关调控机制尚不明确。申请者首先通过生物信息学分析发现，USP33蛋白在卵巢癌中表达水平高于其它众多肿瘤，位居第二；且其在mRNA水平高表达与短生存期密切相关，结果提示USP33可能参与调控卵巢癌进展。通过蛋白组学和修饰组学研究发现USP33与CBX2相互作用，且USP33能够去泛素化调节CBX2，促进其升高和稳定，进而促进卵巢癌发展。具体机制包括：USP33-USP与CBX2-D2结构域相互作用；USP33去泛素化CBX2中K27和K48连接的泛素化，增加其稳定性。进一步研究发现赖氨酸乙酰转移酶GCN5诱导CBX2在K199位点发生乙酰化，且该效应能够增强CBX2与USP33相互作用，促进CBX2去泛素化和稳定。体内外功能学实验结果表明，USP33以CBX2依赖的方式促进卵巢癌的增殖和转移。临床患者组织检测检测结果显示USP33蛋白表达水平显著高于癌旁组织，且其蛋白水平与CBX2呈正相关。组织芯片结果显示在蛋白水平上，USP33和CBX2表达亦呈正相关；USP33或CBX2蛋白高表达与卵巢癌患者短生存期相关。由此可见，USP33一方面通过去泛素化作用调节CBX2的表达和稳定，促进卵巢癌的增殖、迁移和侵袭。另一方面，GCN5诱导CBX2在K199位点的乙酰化作用增强CBX2与USP33相互作用，促进CBX2去泛素化和稳定。本项目研究结果表明USP33-CBX2信号抽可促进卵巢癌的发生发展，有望成为卵巢癌治疗的新靶点。