UCA1结合hnRNP I/L参与膀胱癌细胞谷氨酰胺依赖的三羧酸循环回补机制

It has become acknowledgement that the increase of glutamine utilization is one of the prominent features in the metabolic reprogramming of tumor cells. Previous studies in our lab indicated that lncRNA-UCA1 could upregulate the expression of HK2 via activating mTOR-STAT3 pathway and/or inhibiting miR-143 expression, which promoted the aerobic glycolysis in the bladder cancer cells. Moreover, we found that overexpression of UCA1 resulted in increased glutamine consumption, mitochondrial copy numbers, ATP, mitochondrial membrane potential, as well as expression of glutaminase 2 (GLS2) in bladder cancer cells, indicating that UCA1 participates in the metabolic reprogramming. However, the mechanism by which UCA1 promotes the proliferation of tumor cells through the regulation of glutamine metabolism is still unclear. Combined with existing research, we hypothesize that UCA1 could be combined with heterogeneous nuclear ribonucleo protein I/L (hnRNP I/L) and the complex could transcriptionally activate the expression of glutaminase 2 (GLS2) and glutamic pyruvate transaminase 2 (GPT2), which are critical enzymes for the glutamine metabolism pathway. In further, we will investigate the role of UCA1 played in the glutamine-driven TCA anaplerosis by gain-of-function or loss-of-function of UCA1 experiments in bladder cancer tissues, cells and nude mice xenograft models. Based on these results, we will systematically confirm the influence of UCA1 on tumor cell metabolism and proliferation via glutamine metabolism, uncover the mechanism by which UCA1, combined with hnRNP I/L, is involved in the glutamine-driven TCA anaplerosis. In this study, we will reveal the molecular mechanism of UCA1 involved in bioenergy metabolism in bladder cancer cells and provide novel experimental basis of lncRNA regulating metabolic reprogramming in tumor cells.

对谷氨酰胺的利用增加是肿瘤细胞代谢重编程中的一个突出特点。我们的前期研究发现在膀胱癌细胞中lncRNA-UCA1可以通过激活mTOR-STAT3通路或/和抑制miR-143的表达，上调HK2的表达促进膀胱癌细胞的有氧糖酵解；过表达UCA1可促进谷氨酰胺消耗，增强线粒体的拷贝数、ATP产生、线粒体膜电位及相关标志物的表达和GLS2表达上调。故推测UCA1可能通过调节谷氨酰胺代谢影响肿瘤细胞的增殖。结合已有的研究，拟利用细胞分子生物学和实验动物学的技术方法，从膀胱癌组织、细胞和分子水平综合研究UCA1与hnRNPI/L的结合模式及其对谷氨酰胺代谢相关酶GLS2和GPT2等分子的转录调节，证实UCA1在谷氨酰胺驱动的TCA循环回补机制中的作用及对肿瘤细胞生长代谢和增殖的影响，从而为阐明UCA1参与膀胱癌细胞能量代谢的分子机制和长非编码RNA在肿瘤细胞代谢重构中的调控作用提供新的依据。

对谷氨酰胺的利用增加是肿瘤细胞代谢重编程中的一个突出特点。我们前期研究发现：①在膀胱癌细胞中UCA1可以通过激活mTOR-STAT3通路或/和抑制miR-143的表达，上调HK2的表达促进膀胱癌细胞的有氧糖酵解；②过表达UCA1可促进谷氨酰胺消耗，增强线粒体拷贝数、ATP产生、线粒体膜电位及相关标志物的表达和GLS2表达上调。在前期试验的基础上，我们利用细胞分子生物学和实验动物学的技术方法，从膀胱癌组织、细胞和分子三个层面研究并证实：在膀胱癌中高表达的UCA1、 hnRNP I/L能够结合形成复合物，影响膀胱癌细胞的糖酵解、TCA循环、谷氨酰胺代谢过程和细胞增殖；UCA1与hnRNP I/L特异结合形成的复合物能够与GPT2启动子区域结合，上调GPT2的表达，促进三羧酸循环循环中谷氨酰胺生成的碳源增加，调控谷氨酰胺驱动的三羧酸循环回补从而影响细胞殖。我们的研究揭示了 UCA1 在谷氨酰胺驱动的回补中的关键作用，为lncRNAs 在肿瘤细胞代谢重编程中的调控作用提供了新的证据。