基于STAT3通路的雷公藤红素衍生物抗卵巢癌干细胞的作用机制及结构优化研究

Ovarian cancer is the most common gynecological oncology with high incidence and poor prognosis. Recurrence and metastasis are the leading causes of death. The cancer stem cells (CSCs) have been verified as the primary cause of recurrence and metastasis in cancer. Current clinical drugs can inhibit ovarian cancer cells well, but have very weak inhibitory effect on CSCs, and can promote the self-renewal of CSCs through the activation of STAT3 pathway. We have previously reported that celastrol, a pentacyclic triterpenoid isolated from triterygium wilfordii Hook.f., can attenuate stem cell characteristics in ovarian cancer cells. Furthermore, our pretest study found that one of celastrol derivatives WP02 showed improved anti-ovarian cancer activity targeting CSCs and down-regulated the expression of p-STAT3, but the mechanism is still unknown. This project aims to systematically evaluate the effect of WP02 on the inhibitory activity and stem cell properties of ovarian cancer stem cells, then combined experimental and computational effects to delineate the mechanism of action through which the celastrol derivative targets STAT3. Based on the crystal structure of STAT3 SH2 domain, compounds with high activity will be further designed and optimized to further improve their anti-CSCs activity and STAT3 inhibition. Then the target compounds will be synthesized, characterized and evaluated the anti-ovarian cancer activity in vitro and in vivo in order to obtain the structure activity relationships and investigate mechanism of action. The results would contribute to develop a novel group of anti-CSCs agents as promising candidates for the treatment ovarian cancer.

卵巢癌是死亡率居首位的妇科肿瘤。现有的临床治疗药物对肿瘤干细胞（CSCs）杀伤作用不足，且能活化STAT3通路促进CSCs自我更新，导致复发和转移，是卵巢癌难治的根本原因。开发具有STAT3抑制活性的靶向CSCs药物是解决上述问题的有效途径。申请者前期研究发现，天然三萜类化合物雷公藤红素具有一定的抗卵巢癌CSCs活性，经结构修饰后得到衍生物WP02对CSCs抑制活性增强且可下调p-STAT3蛋白的表达，但具体调控机制尚不明确且活性有待提高。在此基础上，本项目拟通过评价WP02对卵巢癌CSCs的特异性杀伤作用，阐明其调控STAT3通路的作用机制，确证其抗卵巢癌作用靶点；基于STAT3晶体结构，引入具有抗CSCs活性的结构片段，设计优化WP02；完成目标化合物的合成表征、体内外抗卵巢癌活性和构效关系研究，阐明作用机制。本项目将为靶向CSCs药物提供新的候选化合物，也为卵巢癌治疗提供新思路。

卵巢癌是女性生殖系统三大恶性肿瘤之一，死亡率居首位，严重威胁女性生命和健康。卵巢癌复发和转移的重要原因是现有的化疗药物对肿瘤干细胞（CSCs）杀伤作用不足且能通过上调STAT3通路激活CSCs。因此，寻找具有CSCs抑制活性的药物，探讨其抑制复发转移的作用机制，对提高卵巢癌的治疗效果和改善预后意义重大。雷公藤红素是天然醌甲基型五环三萜类化合物，来源于传统中药卫矛科植物雷公藤，对多种肿瘤细胞具有增殖抑制作用。本项目在研究确定雷公藤红素对卵巢癌CSCs具有抑制作用的基础上，首先对课题组前期发现的WP02类化合物Cel-N进行了抗卵巢癌作用机制研究，发现Cel-N可以抑制具有干性特征（CD44+CD24-和ALDH+）的卵巢癌细胞，还可下调STAT3、p-STAT3（S727）和p-STAT3（Y705）的表达，在体内外均表现出优良的抗卵巢癌作用；之后以Cel-N为先导化合物，主要对其A/B环和C29进行结构修饰，设计合成了雷公藤红素衍生物，筛选得到了活性最佳的化合物6c；最后通过系统的作用机制研究，发现6c同样具有调控STAT3通路和抑制CSCs作用，可以诱导细胞凋亡，抑制侵袭和迁移，可作为候选化合物用于进一步研究。本项目的研究发现了一类具有调控STAT3通路和抑制CSCs作用的雷公藤红素衍生物，将为天然活性产物先导物的发现与结构优化提供参考，也为治疗复发转移性卵巢癌提供新思路。