乙酰基-11-羰基-β-乳香酸及修饰物对前列腺癌多药耐药细胞“干性”维持的干预机制和构效机制研究

Hormone refractory prostate cancer (HRPC) is highly malignant with poor prognosis. Docetaxel is an antimitotic agent currently used as the standard therapy for patients with HRPC. However, resistance to Docetaxel precedes fatality in HRPC. Strategies that target Docetaxel resistant cells remain elusive. Recent study revealed that chemoresistant cancer cells have potent tumor-initiating capacity, providing a novel rationale for the mechanism of multidrug resistance and a novel strategy to develop chemotherapeutic drugs. In our previous studies, we generated in vitro Docetaxel-resistant model (PC3/Doc cells) using the well-established HRPC cell line PC3, and determined PC3/Doc cells notable stem-like phenotype, with aberrant activation of different stemness maintenance associated signaling pathways. Antitumoral activity screening of natural terpenoids revaled that PC3/Doc cells were more sensitive to acetyl-11-keto-β-boswellic acid (AKBA) than PC3 cells. Further study showed that PC3/Doc cells lost tumor-initiating capacity after treated with AKBA, and various stemness marker genes activated by different signaling pathways were down-regulated. Given the results, we hypothesized that AKBA suppressed multidrug resistant HRPC via blocking stemness maintenance associated signaling transduction network. This project will test this hypothesis using in vitro and in vivo models, and is aimed at elucidating the underlying mechanism of AKBA, analyzing the structure-activity mechanism of AKBA and its derivatives, validating AKBA as a novel lead compound to treat chemoresistant prostate cancer.

激素难治性前列腺癌恶性程度高，多烯紫杉醇是目前唯一可明显延长其患者生存期的化疗药物，但因多药耐药严重制约治疗效果。前列腺癌耐药机制和化疗药物研究亟待突破。课题组前期通过构建前列腺癌多药耐药细胞模型，发现并明确了其显著的干细胞样表型，多条“干性”相关信号通路均异常活化。而经筛选显示耐药细胞对天然化合物乙酰基-11-羰基-β-乳香酸（AKBA）敏感性显著高于其母代细胞；且经AKBA干预后其干细胞样特性受到显著抑制，多种受不同信号通路调控的“干性”维持相关基因表达下调，提示AKBA通过阻断“干性”信号应答网络杀伤耐药细胞的作用机制。本项目延续前期研究，拟以AKBA为代表研究能阻断前列腺癌耐药细胞“干性”维持的先导化合物，通过多药耐药动物模型获得AKBA杀伤体内耐药细胞的可靠证据，并利用AKBA及修饰物探讨其构效机制，为研制针对多药耐药前列腺癌的创新药物提供依据。

前列腺癌发展为激素难治性前列腺癌（HRPC）后，恶性程度高、死亡率高，以多烯紫杉醇为基础的化疗是临床首选的治疗手段，但后续产生的多药耐药问题严重制约治疗效果。本课题基于肿瘤耐药的干性机制，通过构建HRPC耐药细胞模型和动物模型，首先证实了其显著的干细胞样表型，探讨了干性相关基因在耐药细胞中的表达情况及干性信号通路的活化状态，确定多种干细胞标志蛋白表达显著上调；同时以IL6/STAT3和IGF1R/AKT信号通路的异常活化最为显著，且两者对HRPC耐药细胞干性维持发挥重要作用。利用我们构建的耐药模型并基于上述干性相关耐药机制，我们对多种天然萜类小分子进行了抗肿瘤活性筛选与干性抑制活性分析，确定天然三萜类化合物乙酰基-11-羰基-β-乳香酸（AKBA）对HRPC耐药细胞的抑制作用显著，并进行了AKBA同系物的结构与活性分析。进一步研究发现AKBA明显抑制耐药细胞的干细胞样表型，且能够同时阻断耐药细胞IL6/STAT3和IGF1R/AKT信号通路的激活而降低SOX2等多种干性基因的表达，进而有效消除耐药细胞干性特征而发挥抗HRPC耐药作用。动物实验证实了AKBA对体内耐药细胞的杀伤作用和干性抑制活性，同时分析了AKBA对动物肝、肾功能的影响。此外在研究过程中，发现低剂量AKBA能够诱导肿瘤细胞衰老的发生，从而抑制肿瘤细胞的增殖，此抗肿瘤活性同时在动物体内得到验证。综上所述，本研究工作明确了AKBA显著抑制干性活性、显著诱导细胞衰老、且毒性低的药理学活性，说明其具有多靶点抗肿瘤的独特之处。因此，本课题的研究不仅阐明了干性机制参与HRPC耐药过程，而且发现了新的具有抗干性活性的逆转耐药化合物AKBA，研究具有创新性，这些研究工作为HRPC的治疗提供了新思路和新途径，并为AKBA作为此类药物的先导化合物用于HRPC患者的治疗或作为化疗增敏剂提供了转化医学依据。