长非编码RNA PIL-1调控Pin1影响乳腺癌干性促进化疗耐药的作用和机制研究

The prolyl isomerase Pin1 is an oncogene that overexpressed in over 60 human cancer types. Its substrates include multiple important oncogenes and tumor suppressors. We have reported that Pin1 regulates the expansion and tumorigenicity of breast cancer stem cells through downstream targets including Rab2A. The interaction of Pin1 and its substrates is specifically regulated, but the mechanism is largely unknown. Recently long non-coding RNAs (lncRNAs) have been gained attention for their critical roles in fine-tuning protein interactions. In our preliminary experiments, using RNA immunoprecipitation and deep sequencing, we have identified a batch of lncRNAs that interact with Pin1, among which is lncPIL-1 (Pin1-interacting lncRNA-1). We have showed that lncPIL-1 overexpression correlates with poor survival of breast cancer patients. Knockdown of lncPIL-1 suppresses the stemness phenotype and increases chemoresistance of breast cancer cells. Here we will demonstrate the role and explore the mechanism of how lncPIL-1 interact with Pin1 to regulate breast cancer stem cells and chemoresistance. Furthermore we will explore the potential of lncPIL-1 as a therapeutic target in breast cancer. Our project will not only uncover a novel regulating mechanism of Pin1 by lncRNAs, but also will help to develop novel target strategies towards lncRNAs in inhibiting breast cancer stem cells and treating chemoresistance.

肽基脯氨酰异构酶Pin1在60余种恶性肿瘤中高表达，其底物包括多种重要癌基因和抑癌基因。我们已发表系列文章报道Pin1通过Rab2A等下游分子增加乳腺癌干细胞自我更新和致瘤能力。Pin1与底物的作用受到特异调控，但机制不明。近年发现lncRNA在蛋白功能的精细调控中发挥重要作用。我们前期通过RNA免疫沉淀联合深度测序鉴定了一批与Pin1结合的lncRNA，发现其中的lncPIL-1（Pin1-interacting lncRNA-1）在乳腺癌的高表达与患者预后不良相关，敲降后抑制乳腺癌干性表型并增加对化疗药物敏感性。本项目拟基于此深入研究lncPIL-1与Pin1结合、调控乳腺癌干性促进化疗耐药的作用和具体机制，探讨lncPIL-1作为乳腺癌干细胞和化疗耐药治疗靶点的可能性。将阐明lncRNA调控Pin1功能的新机制，有望发现可作为肿瘤治疗靶标的、促进肿瘤干性转化和化疗耐药的lncRNA。

本项目立项前已经发现长非编码RNA lncPIL-1影响乳腺癌细胞的干性特征和化疗耐药。本项目计划研究lncPIL-1如何调控乳腺癌干细胞和化疗耐药，以及lncPIL-1通过哪些信号通路发挥作用，具体的调节机制如何。本项目按计划执行，我们发现lncPIL-1在乳腺癌中高表达不仅调控乳腺癌干性表型并增加对化疗药物敏感性，其更为突出的功能是调控免疫相关的信号通路，抑制免疫细胞浸润，发挥肿瘤免疫抑制作用。此外，我们还发现了一个多种肿瘤依赖的lncRNA APAL，高表达APAL的肿瘤细胞敲降APAL后会出现有丝分裂灾难继而引发细胞凋亡。不仅首次揭示APAL对于Aurora A激活PLK1的调控作用，而且APAL在多种肿瘤的高表达不但使其有望成为肿瘤预后标志物，更由于其肿瘤依赖特性成为肿瘤治疗的靶点分子。同时，我们在胃癌中鉴定出一条增加化疗耐药的lncRNA OVAAL。OVAAL在胃癌中过表达增强了核苷酸嘧啶的合成，促进了胃癌细胞的增殖和5-FU耐药性，并且这种效应可以通过降低与OVALL结合的丙酮酸羧化酶（PC）来消除。因此，靶向OVAAL介导的核苷酸代谢重编程将是克服胃癌化疗耐药性的一种有效策略。综上，本项目围绕促进肿瘤进展和耐药的lncRNA开展研究，阐明了这些lncRNA在肿瘤中的作用和调控机制，并探讨了其作为肿瘤治疗靶点的可能性。不仅对于揭示lncRNA的功能和对肿瘤的调控机制具有理论价值，还将有可能开发新的肿瘤治疗靶标，抑制肿瘤进展和化疗耐药。