去泛素化酶OTUB2与转录因子GATA2正反馈环路促进结肠癌转移的机制研究

转录调控异常是恶性肿瘤的典型特征，在驱动肿瘤转移中发挥重要作用。大规模生信分析和预实验发现，GATA2可能是维持结肠癌异常转录组的核心转录因子，但其促进结肠癌侵袭转移的上下游调控机理尚不清楚。采用蛋白质谱和免疫共沉淀试验发现，GATA2可能被去泛素化酶OTUB2识别，在翻译后水平维持其蛋白稳定性；联合分析RNA-seq和ChIP-seq高通量测序结果则表明，结肠癌高表达的GATA2可能在转录水平激活OTUB2和上皮间质转化关键基因Vimentin等表达，促进高侵袭转移特性。因此提出科学假说：GATA2可能与OTUB2形成正反馈环路，通过去泛素化作用上调GATA2表达，持续激活其下游侵袭转移相关基因，导致肿瘤转移。本项目拟采用多种细胞分子生物学技术及结肠癌转移模型，揭示结肠癌侵袭转移的泛素化-转录调控环路新机制，发掘转移性结肠癌的精准干预新靶点。

Dysregulated transcriptional control is a hallmark of human malignancies and plays a major role in driving tumor metastasis. By massive bioinformatic analysis of the publically available transcriptome datasets, we identified a core transcription factor GATA2 that may dictate a large portion of the aberrantly expressed genes in colon cancers. GATA2 is highly elevated in colon cancer tissues to maintains cell motility and invasiveness, however its upstream and downstream regulatory mechanisms remain unknown. To this end, through mass spectrometry and co-immunoprecipitation assays, we have found a deubiquitinase OTUB2 that may potentially upregulate GATA2 at post-translational level. Moreover, GATA2 was found to directly regulate OTUB2 and several key genes that are essential for epithelial to mesenchymal transition at the transcriptional level by combined analysis of RNA-seq and ChIP-seq data. In light of these findings, we propose that GATA2 may form a positive feedback loop with OTUB2 to stabilize itself through deubiquitination, which subsequently leads to consistent activation of a pro-metastatic transcriptional profile to maintain colon cancer metastasis. To challenge this notion, a serial of molecular and cellular techniques will be applied to examine how GATA2 and OTUB2 regulate either other at both post-translational and transcriptional levels. We will also test how the GATA2-OTUB2 feedback circuit controls downstream target genes to empower tumor metastasis in vivo, which might identifies potential molecular targets actionable for treating metastatic colon cancers in clinical settings.