细胞分裂调控蛋白42对卵巢癌干细胞侵袭能力的调控作用及机制研究

Epithelial ovarian cancer is the leading cause of gynecological cancer mortality. Over 75% of the patients developed recurrence ultimately. Recent reports showed that cancer stem cells (CSCs) might be the root of relapse. Our previous work have identified CSCs in ovarian cancer from the isolation of side-population cells and spheres, with the properties including self-renewal, high efficiency of tumorigenesis and resistance to chemotheray. The further experiment found that cell division control protein 42 (Cdc42) was overexpressed in ovarian CSCs and clinical specimens of ovarian cancer patients. The overexpression of Cdc42 was significantly correlated with FIGO advanced stages and relapse. Hence our project will aim to explore the role of Cdc42 in regulation of CSC properties and invasion in ovarian cancer. We propose to take advantage of sphere culture and NSG mice and carry out CRISPR/Cas9 gene editing and lentiviral transfection. The role and mechanism of Cdc42 in regulating the invasion ability of ovarian CSCs will be elucidated. Furthermore, the relationship of Cdc42 and ovarian cancer recurrence will be validated by immunohistochemistry of clinical samples. Accomplishment of this proposal will not only help make breakthrough in the mechanism of ovarian cancer invasion and relapse, but also provide a molecular basis for prediction of recurrence and targeted therapy.

卵巢癌的致死率在女性生殖器官恶性肿瘤中居首位，超过75%的患者出现复发。肿瘤干细胞（CSCs）可能是导致肿瘤复发的根源。我们在人卵巢癌细胞系SP细胞分选和球形体培养中证实卵巢癌CSCs的存在且CSCs具有自我更新、高成瘤、化疗耐药的特性，进一步研究发现在卵巢癌细胞系CSCs存在细胞分裂调控蛋白 42（Cdc42）的高表达，并通过临床标本验证发现Cdc42在卵巢癌组织中表达增高，并且Cdc42高表达与FIGO分期晚、复发显著相关。由此，本项目拟研究Cdc42在调控卵巢癌干细胞特性和侵袭能力中的重要作用及机制。我们将以sphere培养技术和NSG小鼠致瘤模型为基础，应用CRISPR/Cas9基因编辑和慢病毒转染进行功能实验，分析Cdc42对卵巢癌干细胞侵袭能力的影响及相关机制，并在临床标本中进行验证。本项目期望在揭示卵巢癌侵袭和复发机制上取得突破，为临床预测肿瘤复发、指导靶向治疗提供依据。

卵巢癌是死亡率最高的女性生殖器官恶性肿瘤，超过70%的患者在诊断时已进入临床晚期。目前，治疗IC-IV期卵巢癌的规范化方案是在理想肿瘤细胞减灭术的基础上辅以紫杉醇+铂类的一线联合化疗方案，但最终仍有超过75%的患者出现肿瘤耐药复发，晚期卵巢癌的5年生存率始终徘徊在30%左右。深入研究卵巢癌复发转移机制对于提高卵巢癌的治疗效果有重要的现实意义。近年来的研究表明，肿瘤干细胞（CSCs）有极强的自我更新能力和无限增殖能力，对化疗药物有抵抗能力，是导致肿瘤复发及耐药的根源。.比起血行转移和淋巴转移，卵巢癌通常通过肿瘤直接浸润和经腹水的腹膜种植转移到周围器官，该机制是否与卵巢癌干细胞相关还不清楚。我们的研究发现细胞分裂调控蛋白Cdc42调控卵巢癌干细胞特性，与肿瘤转移及化疗耐药密切相关。体外实验表明，Cdc42介导了卵巢癌干细胞sphere形成和凋亡、细胞迁移及化疗耐药。下调Cdc42能增加SKOV3细胞对紫杉醇的敏感性。动物实验表明，下调Cdc42的SKOV3细胞成瘤能力明显下降。102例临床组织标本免疫组化分析表明增加的Cdc42表达与缩短的PFS和OS相关。因此，本研究表明Cdc42在卵巢癌的形成、转移和化疗耐药扮演了重要调控角色，针对Cdc42进行靶向治疗可能有助于卵巢癌的治疗。