HOTAIR—EZH2—STAT3环路通过调控肿瘤干细胞干性介导上皮性卵巢癌顺铂耐药的作用研究

Our study confirms that EZH2 is involved in mediating cisplatin resistance in epithelial ovarian cancer (EOC), but the mechanism is unknown. In consideration of the important role of tumor stem cells (CSCs) in tumor resistance, we try to use it as a starting point. STAT3, which is involved in the maintenance of CSCs characteristics can regulate the expression of long non-coding HOTAIR in lung disease. In addition, we found that down-regulation of EZH2 or HOTAIR could inhibit the activity of STAT3, and EZH2 was positively correlated with STAT3 in EOC cells. Based on this, we hypothesize that the presence of HOTAIR-EZH2-STAT3 positive feedback may mediate EOC cisplatin resistance by maintaining CSCs characteristics. We identified CSCs from EOC cells, and used lentivirus mediated regulation of HOTAIR-EZH2-STAT3 in a separate or joint way to verify the path, and resistance experiment, clone formation and function of tumor experiments to test the changes of characteristics of CSCs and cisplatin resistance in EOC. Our aim is to clarify the mechanism of EZH2 mediated cisplatin resistance of EOC, find the key point for reversing cisplatin resistance in EOC.

我们研究证实EZH2参与介导上皮性卵巢癌（EOC）顺铂耐药，但机制不明，介于肿瘤干细胞(CSCs)在肿瘤耐药中的重要作用，我们试图以它为切入点。研究报道，STAT3参与维持CSCs干性且肺病中STAT3可调节长链非编码RNA HOTAIR表达，我们研究发现在分离的肿瘤干细胞样细胞中下调EZH2/HOTAIR表达可抑制STAT3活性，在EOC细胞中EZH2与STAT3呈正相关。据此我们假设HOTAIR-EZH2-STAT3正反馈通路的存在并通过维持CSCs干性来介导EOC顺铂耐药。我们提取鉴定出EOC肿瘤干细胞，慢病毒介导单独/联合调控HOTAIR-EZH2-STAT3中一环验证该通路的存在，耐药实验、克隆形成及成瘤实验检验该通路对CSCs特性调控及EOC顺铂耐药的作用，旨在阐明EZH2介导EOC顺铂耐药的机制，找到逆转EOC顺铂耐药的关键切入点。

卵巢癌是病死率最高的妇科恶性肿瘤，其标准治疗为细胞减灭术后顺铂为主的化疗，而化疗耐药是导致卵巢癌综合治疗失败、病死率高的重要原因，而这一原因极可能由卵巢癌干细胞（OCSCs）介导。上皮性卵巢癌是卵巢癌最主要的病理类型，约占90%。因此，研究上皮性卵巢癌顺铂耐药发生机制找到关键因子，对逆转其化疗耐药提高患者生存率至关重要。在本研究中，我们主要从长非编码RNA-HOX转录反义基因间RNA(Hotair)角度，探讨了导致卵巢癌耐药的“罪魁祸首”OCSCs的性能维持机制。通过高醛脱氢酶（ALDH）活性或体外成球能力鉴定出OCSCs，发现HOTAIR在OCSCs中高表达，敲出HOTAIR后肿瘤干细胞成瘤能力减弱，伴随细胞顺铂耐药性及裸鼠体内致瘤性的降低。T-box转录因子3（TBX3）在OCSCs中高表达，并证实其受HOTAIR正向调控。此外，TBX3维持了细胞的干性，而升高TBX3可以削弱由敲出HOTAIR诱导的细胞成瘤能力减弱。随后，我们发现miR-206介导了HOTAIR对TBX3的表达调控，在功能上参与OCSCs干细胞的调控。与这些结果一致，卵巢癌患者循环HOTAIR表达上调。综上所述，我们的研究表明HOTAIR可以减轻miR-206介导的TBX3表达抑制为卵巢癌的治疗提供了新的靶点。