G6PD蛋白K386位点的去乙酰化通过重编程糖脂代谢促进结直肠癌耐药的研究

The presence of drug resistance often leads to the failure of cancer treatment. The nature of tumor evolution is the major cause of drug resistance. In view of this, the applicant established a a dynamic model of drug resistance in colorectal cancer using 3D culture and patient-derived xenograft based on tumor evolution theory. Analysis of multidimensional databases of genomics, proteomics and metabolomics related to drug resistance, we found that G6PD-mediated reprogramming of glucose and lipid metabolism is an important cause of cytotoxic and targeted drug resistance. In addition, we found that deacetylation of the K386 site in the G6PD protein results in dysregulation of membrane proteins due to lipid changes, which is a key mechanism associated with drug resistance. More importantly, we found that specific acetylated deacetylase that regulate the K386 site of the G6PD protein is a potential target for improving drug resistance in colorectal cancer. Therefore, the theory of metabolic selection that promotes the evolution of cancer drug resistance is proposed. In support of this idea, the project will focus on the logical relevance of deacetylation/metabolic reprogramming/drug resistance. We will investigate the molecular mechanism of deacetylation at the G6PD K386 site. Then we will analyze the reprogramming effect of K386 deacetylation on glucose and lipid metabolism and the effect K386 acetylation on drug resistance. Through this study, we may gain new insights into cancer cell resistance and may find new targets for improving drug resistance.

细胞耐药性的存在常导致肿瘤治疗失败，肿瘤进化的特质是耐药性形成的重要原因。鉴于此，申请人以肿瘤进化论为指导，应用三维培养及人源肿瘤异种移植的方法，建立了可动态观测的结直肠癌耐药模型。通过基因组学、蛋白组学和代谢组学多维数据集在耐药前后的比对分析和讨论，研究发现G6PD介导的糖脂代谢重编程，是引起肿瘤细胞对细胞毒性和靶向药物同时产生耐药性的重要原因；而K386位点去乙酰化的G6PD蛋白通过脂质对膜蛋白的调节，是导致细胞耐药的关键机制；调节G6PD蛋白K386位点修饰的去乙酰化酶，则是改善结直肠癌耐药的潜在靶点。基于此，我们提出“代谢选择驱动肿瘤耐药进化”的理论，本项目将围绕去乙酰化→代谢重编程→肿瘤耐药的逻辑链论证该理论，通过阐明G6PD的K386位点去乙酰化修饰的机制，并揭示K386位点去乙酰化对糖脂代谢重编程、药物敏感性的调节作用，以期使我们对肿瘤细胞的耐药性产生新的认识、发现新的靶点。

代谢重编程是肿瘤细胞的标志之一，糖酵解途径、磷酸戊糖途径和脂质从头合成途径为肿瘤细胞的快速增殖提供能量和原料。在本基金的资助下，研究者着重关注糖酵解途径关键酶PKM2、磷酸戊糖途径关键酶G6PD、脂质从头合成途关键酶ACLY。研究发现PKM2 K62位点去乙酰化与HCC的预后有关。K62去乙酰化促进PKM2转运至细胞核并结合β-连环蛋白，从而促进CCND1基因转录和细胞周期进展。此外，K62去乙酰化影响PKM2的酶活性和葡萄糖代谢通量。HDAC8结合并去乙酰化PKM2的K62位点，为靶向HDAC8-PKM2调控轴治疗肝细胞肝癌的靶向药物提供理论依据（2020 Cell Death and Disease）。在本基金的资助下，研究发现结直肠癌在耐药过程中G6PD K386位点乙酰化降低，细胞内谷胱甘肽水平下降、NADPH产生减少；并进一步明确了该位点的去乙酰化酶，以及K386位点突变后对G6PD的功能影响，去乙酰化酶特异性抑制剂对结直肠癌的化疗增敏作用（投稿中）。另外，研究者发现，沉默ACLY明显削弱结肠癌细胞在体外和体内的转移能力，促使结肠癌细胞间质上皮转化；ACLY可能与CTNNB1相互作用，增加CTNNB1蛋白的稳定性，促进更多的CTNNB1积聚于细胞核，进而促进结肠癌细胞的转移，为结直肠癌的转移提供理论依据（2019 Journal of Experimental & Clinical Cancer Research）。

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