CypA/Nrf2复合物在非小细胞肺癌氨基酸代谢异常中的作用、机理研究及靶向药物发现

It is important to find out the driver proteins and control network in tumor cell metabolism. In our previous work, we found that in non-small cell lung cancer (NSCLC), cyclophilin A (CypA) is involved in the biosynthesis of serine/glycine. HL001- a CypA inhibitor specifically suppressed the survival of NSCLC cells which harboring an increased content of serine and glycine. Our further results indicated that CypA can directly bind and activate Nrf2. Nrf2 is a key transcription factor that regulate antioxidant defense, and has been widely reported in regulating the metabolism of cancer cells in recent years. Based on the above results, we want to further investigate the structure and bio-functions of CypA/Nrf2 complex. Which include getting the binding site information of CypA/Nrf2 and the regulation mode of CypA/Nrf2 in serine/glycine metabolism of NSCLC cells, finding out if CypA/Nrf2 complex triggers the metabolic reprogramming in NSCLC. We also need to set up the screening method searching CypA/Nrf2 inhibitors, used both cell and animal modes to clarify the anti-tumor activities of CypA/Nrf2 small molecule inhibitors in NSCLC cells. Finally, provide theoretical and experimental basis for the development of new anti-NSCLC drugs.

对肿瘤代谢异常进行系统研究，发现并揭示肿瘤代谢异常的关键蛋白及分子调控网络，对我国的肿瘤化学预防与靶向治疗具有重大意义。我们前期研究发现亲环素A（CypA）参与调控非小细胞肺癌（NSCLC）中丝氨酸/甘氨酸代谢，其小分子抑制剂HL001对丝氨酸/甘氨酸含量升高的NSCLC细胞具有显著的杀伤活性。初步机理研究表明，CypA可直接结合并激活转录因子Nrf2。Nrf2是细胞防御氧化应激的重要调节因子，近年来研究表明Nrf2广泛参与了肿瘤细胞的氨基酸代谢。因此，本项目拟利用代谢组学、功能基因组学、复合物晶体和NMR等手段：确证CypA和Nrf2相互作用的关键位点；明确CypA通过Nrf2调控NSCLC细胞丝氨酸/甘氨酸代谢的作用机制；构建CypA/Nrf2抑制剂筛选方法；筛选及确认CypA/Nrf2小分子抑制剂对NSCLC的增殖抑制活性。为研发新型NSCLC治疗药物提供理论基础和实验依据。

肺癌是全球范围内发生率和死亡率最高的癌症之一，其中85%以上为非小细胞肺癌(NSCLC, non-small cell lung cancer)。Nrf2 (nuclear factor erythroid 2-related factor 2)是细胞内重要的氧化应激调控因子。细胞内Nrf2的水平主要受KEAP1(E3 ligase adaptor Kelch-like ECH-associated protein 1)泛素化降解调控，过度活化的Nrf2与肿瘤快速增殖密切相关。而近20% KRAS突变的NSCLC中存在KEAP1突变，导致Nrf2过度活化。本课题针对谷氨酰胺代谢依赖的非小细胞肺癌中过度活化的转录因子Nrf2进行降解型抑制剂筛选，发现CypA抑制剂CsA能够促进Nrf2蛋白降解，通过点突变、ITC及复合物晶体结构解析等手段确证CypA通过酶活口袋与Nrf2相结合，抑制其泛素化降解从而稳定Nrf2蛋白。谷氨酰胺剥夺实验以及海马实验证明CypA/Nrf2通路可以影响肿瘤细胞中的谷氨酰胺代谢。RT-PCR及转录调控分析证实了Nrf2可通过KLF5调控谷氨酰胺转运体蛋白SLC1A5转录，影响细胞内的谷氨酰胺代谢，促进肿瘤细胞增殖。体内外实验表明Nrf2降解剂CsA与谷氨酰胺酶抑制剂CB-839联用可增强对NSCLC肿瘤的生长抑制。在自然基金资助下，发现了CypA调控Nrf2蛋白稳定性的新机制，针对KRAS/KEAP1双重突变的NSCLC，提出了协同靶向Nrf2降解与谷氨酰胺酶抑制的治疗新策略。发表受本基金资助的SCI论文8篇，申请相关国内专利2项，培养毕业博士研究生3名，硕士研究生3名。