The Role and Regulation of Monocarboxylate Transporters 1 and 4 in Epstein-Barr Virus-mediated B Lymphocyte Tumorigenesis

EB病毒（Epstein-Barr Virus，EBV）是一种普遍存在的病毒，其在初次感染后建立潜伏期，但可劫持宿主 代谢途径，以促进免疫受损宿主的肿瘤发生。本提案的目的是 确定EBV如何通过MCT 1和MCT 4调节乳酸输出，可以促进B细胞永生化， 并用于治疗。我的中心假设是EBV暂时上调MCT 1/4， 通过减轻永生化过程中增加的细胞内乳酸负荷来促进B细胞生长。 这一假设基于乳酸输出对于防止细胞内酸化至关重要的基本原理， 这可能对细胞生长有害。我们的实验室已经发表，在EB病毒永生化的B细胞 在体外，糖酵解显著上调。我们还观察到细胞外酸化率增加 （ECAR），这在很大程度上反映了糖酵解过程中分泌的乳酸。然而，乳酸输出在 EBV介导的B细胞永生化从未被探索过。乳酸输出受血浆调节 膜驻留蛋白单羧酸转运蛋白1和4（MCT 1/4），已与 在各种癌症中的肿瘤发展和进展。我们已经观察到细胞外 和EBV B细胞永生化过程中细胞内乳酸水平。在体外，B的EBV永生化 细胞转化为无限增殖的淋巴母细胞样细胞系（LCL）诱导了两种不同的潜伏期程序， IIb和潜伏期III。LCL表达潜伏期III生长程序，其中所有六种EBV核抗原（EBNA-100）都是LCL表达的。 LP、1、2、3A、3B和3C）和两种潜伏膜蛋白（LMP 1和LMP 2）。该基因 表达程序模拟了许多EBV相关B淋巴癌的表达程序，使LCL成为合适的模型 用于研究肿瘤发生的潜在机制。感染后不久和潜伏期III建立前 在LCL中，早期EBV感染的B细胞表达潜伏期II B生长程序，其中只有病毒EBNA被 表达。我们已经观察到MCT 1在潜伏期IIb期间上调，而MCT 4在潜伏期III期间上调， 这表明MCT 1/4介导的乳酸盐输出可能对EB病毒驱动的B细胞永生化很重要。我计划 通过追求以下具体目标来检验这一假设： 1.）确定MCT 4上调的病毒机制和在MCT 1抑制剂耐药性中的作用 2.）揭示在双重MCT 1/4抑制中促进生长停滞的潜在变化 3.）第三章探索双重MCT 1/4抑制作为病毒相关淋巴瘤的治疗策略

Epstein-Barr Virus (EBV) is a ubiquitous virus that establishes latency upon primary infection, but can hijack host metabolic pathways to promote tumorigenesis in immune-compromised hosts. The goal of this proposal is to determine how EBV regulation of lactate export through MCT1 and MCT4, can promote B cell immortalization, and be exploited for therapeutic benefit. My central hypothesis is that EBV temporally upregulates MCT1/4 to promote B cell growth by mitigating the increased intracellular lactate burden accrued during immortalization. This hypothesis is based on the rationale that lactate export is crucial for preventing intracellular acidification, which can be detrimental to cell growth. Our laboratory has published that during EBV immortalization of B cells in vitro, glycolysis is significantly upregulated. We also observed increased extracellular acidification rates (ECAR), which is largely a reflection of lactate excreted during glycolysis. However, the role of lactate export in EBV-mediated B cell immortalization has never been explored. Lactate export is regulated by the plasma membrane-resident proteins monocarboxylate transporters 1 and 4 (MCT1/4), which have been associated with tumor development and progression in various cancers. We have observed a significant increase in extracellular and intracellular lactate levels during the course of EBV B cell immortalization. In vitro, EBV immortalization of B cells into indefinitely proliferating lymphoblastoid cell lines(LCLs) induces two distinct latency programs, Latency IIb and Latency III. LCLs express the Latency III growth program, where all six EBV Nuclear Antigens (EBNA- LP, 1, 2, 3A, 3B, and 3C) and two Latent Membrane Proteins (LMP1 and LMP2) are present. This gene expression program mimics that of many EBV-associated B-lymphoid cancers, making LCLs a suitable model for studying mechanisms underlying tumorigenesis. Shortly after infection and prior to Latency III establishment in LCLs, early EBV-infected B cells express the Latency IIb growth program, where only the viral EBNAs are expressed. We have observed that MCT1 is upregulated during Latency IIb, and MCT4 during Latency III, suggesting that MCT1/4-mediated lactate export might be important for EBV-driven B cell immortalization. I plan to test this hypothesis by pursuing the following specific aims: 1.) Determining the viral mechanism for MCT4 upregulation and role in MCT1 inhibitor resistance 2.) Uncovering underlying changes that promote growth arrest in dual MCT1/4 inhibition 3.) Exploring dual MCT1/4 inhibition as a therapeutic strategy in virus-associated lymphomas.