Dicer1调控PGC-1α导致卵巢癌线粒体相关性顺铂耐药的分子机制及靶向治疗研究

Cancer chemotherapy resistance or recurrence are the main causes of poor prognosis of ovarian cancer. It has been reported that low Dicer1 expression was associated with poor prognosis of ovarian cancer, but, the detailed mechanism behind is unknown. Our preliminary results for the first time indicated that low Dicer1 expression increased mitochondria biogenesis and oxidative phosphorylation function activation, enhancing reactive oxygen species (ROS) detoxification capacities, resulting in resistance to Cisplatin. Moreover, we found that this process was accomplished with PGC-1α activation. Therefore, in this project, we intend to verify our findings and to improve this hypothesis in three aspects. Futhermore, we want to explore new combination therapy according to our hypothesis. 1). to reveal the detailed mechanism how Dicer1 regulates the PGC-1α expression through microRNAs (miRs); 2). to further verify the relationship among Dicer1, miRs and PGC-1α in a large samples of ovarian cancer, to explore the correlation between the expression of Dicer1, miRs or PGC-1α and the prognosis of ovarian cancer; 3). to explore the therapeutic effects of new targeted combination therapies in vitro and in vivo based on our hypothesis: using chemotherapy combining with ROS inducer for high Dicer1 expression cells, and using chemotherapy combining with mitochondrial oxidative phosphorylation inhibitors for low Dicer1 expression cells.

化疗耐药或复发是造成卵巢癌预后不良的主要原因。国外报道 Dicer1 低表达和卵巢癌的预后差相关，具体机制不明。我们前期实验结果首次发现Dicer1低表达能够促进卵巢癌线粒体生物合成及功能的活化，同时提高ROS清除能力导致顺铂耐药，且该过程和PGC-1α活化相关。因此在本项目中，我们拟从三个方面验证并完善这个假说，并且根据该假说探索新的联合治疗方案。即：1. 揭示Dicer1通过microRNAs(miRs)调控PGC-1α表达的具体机制；2. 从大样本卵巢癌临床标本中进一步验证Dicer1、miRs、PGC-1α之间的关系，并分析其和卵巢癌患者预后之间的关系；3. 针对我们提出的这个机制，体内外探索新的联合治疗方案的疗效：Dicer1高表达者给予化疗药物联合ROS诱导剂，而对Dicer1低表达者给予化疗药物联合线粒体氧化磷酸化抑制剂。

上皮性卵巢癌（简称卵巢癌）是女性生殖系统常见的恶性肿瘤。目前对卵巢癌，特别是耐药或者复发性卵巢癌的治疗尚无重大突破，成为临床妇产科医生面临的重大困境，也是亟待突破的研究领域。国外临床研究报道，Dicer1 低表达和卵巢癌的预后有关，Dicer1 表达越低，预后越差。我们前期通过对癌症基因组图谱计划 (The Cancer Genome Atlas, TCGA) 中卵巢癌表达谱芯片的数据进行生物信息学数据挖掘，发现Dicer1 低表达的卵巢癌患者在线粒体、电子呼吸链、氧化磷酸化及PGC-1 通路的基因集中存在富集。本课题发现了Dicer1 通过miRs-148b调控PGC-1α 表达的具体机制；并且在临床标本中验证了Dicer1、 miR-148b、PGC-1α 之间的表达相关性和卵巢癌化疗耐药及预后之间的关系。最后 根据我们的发现，针对不同Dicer1 状态，探索不同的联合治疗方案的疗效。Dicer1 高表达的细胞对化疗特别是顺铂敏感，并且联合ROS 诱导剂（如：PEITC、Piperiongumine、PLX4032 等）治疗可增加其疗效；而对Dicer1 低表达细胞卵巢癌细胞对顺铂耐药，然而联合线粒体氧化磷酸化抑制剂（如：CCCP、、oligomycin、phenoformin 等）治疗可以逆转其化疗耐药。特别是不仅在卵巢癌细胞系中验证了phenoformin联合顺铂的协同抗卵巢癌的作用，我们还在8例原代的卵巢癌细胞和卵巢癌移植肿瘤中的协同抗卵巢癌的作用。本课题的意义在于：发现了Dicer1 低表达导致卵巢癌预后差的具体机制研究。并且根据我们发现的机制，合理设计化疗联合线粒体拮抗剂的联合治疗方案，并体内外证实了联合治疗可以逆转卵巢癌化疗耐药。