Dishevelled3及其异构体协同驱动干细胞样表型转化参与结直肠癌耐药的机制与干预策略

Cancer cells gain stem cell-like properties is a key factor of cancer chemoresistance. The stem cell-like phenotype transformation is mediated by multiple signaling. Although it has been confirmed that Wnt signaling is critical for stem cell-like phenotypic transformation, the synergistical mode of multiple signaling in cell remains unexplained. Dishevelled (DVL) with multiple functional domain is involved in signals transduction, and regarded as a key regulator of Wnt signaling pathway. Our preliminary studies have showed that a isomer of DVL3 (DVL3-X2) was overexpressed in drug-resistant colorectal cancer cells, and participated in stem cell-like phenotype transformation and chemoresistance. Therefore, we hypothesized that DVL3-X2 selectively activates bypass signaling due to the lack of DIX and Dishevelled domains, and synergistically mediates the maintenance of colorectal cancer stem cell-like properties and induction of chemoresistance. Therefore, our present proposal will reveal the role and mechanism underlying synergistical driving effect of DVL3-X2 and DVL3 on colorectal cancer stem cell-like phenotype transformation using RNAi, specific anti-agonist, and evaluate the efficiency of improve colorectal cancer chemosensitivity by double-targeting DVL3-X2 and DVL3，and finally supplying a valuable new method for reversing chemoresistance in colorectal cancer.

肿瘤细胞获得干细胞样特性是肿瘤耐药生成的重要原因，而干细胞样表型的转化需要多重信号介导。虽然人们已证实Wnt信号是干细胞样表型转化的关键，但仍无法解释细胞内多重信号的协同方式。散乱蛋白Dishevelled(DVL)通过自身多个功能结构域参与多重信号的传导，是Wnt信号通路的核心调控因子。我们前期研究发现，在结直肠癌耐药细胞中广泛存在DVL3的异构体DVL3-X2，并证实其密切参与了干细胞样表型转化及耐药过程。由此，我们推测DVL3-X2由于缺乏DIX及Dishevelled结构域，选择性活化旁路信号，协同调控了结直肠癌干细胞样特性的维持，诱发耐药的生成。本项目拟在此基础上，通过多种干预措施从分子、细胞及动物模型等层面系统解析DVL3-X2与DVL3协同驱动结直肠癌干细胞样表型转化的内在机制，并评价相关干预措施对改善结直肠癌化疗疗效的有效性，最终为逆转结直肠癌耐药开辟一条有价值的新途径。

肿瘤干细胞样细胞(CSLCs)凭借“自我更新”的特性和长期处于静止期的特点，通过高表达ABC 转运蛋白和抗凋亡基因等而逃避化疗药物杀伤作用，被认为是造成肿瘤耐药、复发转移的罪魁祸首。因此，探明化疗耐药过程中CSLCs表型转化的调控机制，开发靶向肿瘤干细胞的干预措施将是逆转结直肠癌耐药的重要切入点。干细胞样表型的转化需要多重信号介导。Wnt信号核心调控因子Disheveled(DVL)可通过自身多个功能结构域参与多重信号的传导，但在结直肠癌CSLCs表型转化中的作用并不清楚。我们的研究揭示了DVL3及其异构体/家族成员共同驱动结直肠癌CSLCs特性诱发耐药的重要作用及内在机制，评价了相关干预措施对逆转化疗耐药的作用效果。研究发现DVL1-3及DVL3异构体密切介入到结直肠癌CSLCs表型转化过程中，且DVL3与结直肠癌患者总生存期、无病生存期、疾病特异性生存期呈明显负相关。DVL3可上调Wnt/β-catenin/c-Myc/SOX2信号轴促进结直肠癌CSLCs并增强化疗耐药。而异构体DVL3-X2虽丧失了对Wnt/β-catenin信号的调控，但仍可增强干细胞转录因子复合体OCT4/SOX2的形成维系CSLCs特性。研究还发现DVL3及家族成员DVL2还可增强干性相关的EMT从而促进结直肠癌耐药与转移。我们还进一步筛选到天然药物原花青素PC、双氢青蒿素DHA均可同时抑制DVL1-3的表达并削弱CSLCs特性、增强结直肠癌化疗敏感性。我们的研究为靶向肿瘤干细胞的治疗药物研发提供了新的作用靶点，最终为增强结直肠癌化疗的效果开辟一条有价值的新途径。