Synthetic lethal targeting of EBV-positive diffuse large B cell lymphomas in persons living with HIV

项目摘要 弥漫性大B细胞淋巴瘤（DLBCL）是非霍奇金淋巴瘤（NHL）中最常见的类型， 积极的和尽管抗逆转录病毒药物仍然是癌症相关死亡的主要原因， 感染了艾滋病毒值得注意的是，高达90%的HIV-DLBCL对致癌的EB病毒（EBV）呈阳性。因此，在本发明中， 了解EBV如何促进癌症对于发现新的治疗方法至关重要。 癌细胞需要DNA修复，但EBV如何参与和重塑细胞DNA修复是一个未充分探索的问题。 区我们对EBV-癌细胞和EBV-转化的人B细胞（类淋巴母细胞系）的研究，后者 免疫抑制宿主中EBV驱动的淋巴瘤的重要模型，收敛于STAT 3。一个 STAT 3在癌症中经常被激活。一些研究还表明，EBV+ HIV-DLBCL 通常在Janus激酶（JAK）-STAT 3途径中表现出激活突变。我们发现EBV 激活STAT 3以绕过S期检查点屏障，从而确保细胞增殖，但在 过程，失去修复DNA双链断裂（DSB）的同源重组（HR）。因此，EBV- 转化和癌细胞变得依赖于其他形式的DNA修复，特别是， 微同源介导的末端连接（MMEJ）类型的修复。这造成了对合成药物的治疗脆弱性， 对具有完整HR. PARP [聚（ADP-核糖）聚合酶]的细胞无毒的致死剂 抑制剂是靶向MMEJ的合成致死剂之一。事实上，我们发现EBV转化和 癌细胞对靶向PARP和MMEJ特异性DNA聚合酶的MMEJ抑制剂高度敏感， POLθ。支持这种对MMEJ的依赖性，EBV转化的细胞表现出MMEJ的全基因组瘢痕 与EBV + HIV-DLBCL相比，EBV+ HIV-DLBCL显示出更高丰度的STAT 3和POLQ转录物。 肿瘤; POLQ编码POLθ。此外，通过对数百种癌细胞系的多组学分析，我们得到了 鉴定了STAT 3相关的基因表达特征，该特征指向STAT 3与 依赖MMEJ修复，同时预测对合成致死疗法的易感性。 我们现在提出研究EBV如何使用JAK-STAT 3途径重塑DNA修复并使EBV+ HIV-DLBCL易受合成致死治疗靶向的影响。使用细胞系、异种移植物和患者来源的 从NCI艾滋病和癌症标本资源（ACSR）的EBV+和EBV-HIV-DLBCL，我们调查了联系 JAK-STAT 3通路与EBV+ HIV-DLBCL中DSB修复之间的关系（Aim 1），并合成-致死性利用JAK- STAT 3依赖性DNA修复缺陷杀死EBV+ HIV-DLBCL（目的2）。 这些研究通过确定机制和产生新的范例来专门解决PAR-21-348， 揭示EBV如何导致NHL。从长远来看，这些机械的见解将揭示新的漏洞 并能够预测对合成致死疗法的反应，以改善EBV+ DLBCL患者的结局， 艾滋病毒感染者。

PROJECT SUMMARY Diffuse large B-cell lymphoma (DLBCL), the commonest type of non-Hodgkin lymphoma (NHL), is highly aggressive and despite antiretrovirals continues to be a leading cause of cancer-related death in persons living with HIV. Notably, up to 90% of HIV-DLBCL are positive for the cancer-causing Epstein-Barr virus (EBV). Thus, understanding how EBV contributes to cancer is essential to discovering new therapeutic approaches. Cancer cells require DNA repair but how EBV engages and reshapes cellular DNA repair is an underexplored area. Our studies on EBV-cancer cells and EBV-transformed human B cells (lymphoblastoid cell lines), the latter an important model of EBV-driven lymphomas in immunosuppressed hosts, converge on STAT3. An oncoprotein, STAT3 is frequently activated in cancer. Several studies have also shown that EBV+ HIV-DLBCL frequently exhibit activating mutations in the Janus kinase (JAK)-STAT3 pathway. We have found that EBV activates STAT3 to circumvent the S phase checkpoint barrier, thereby ensuring cell proliferation but in the process, loses homologous recombination (HR) that repairs DNA double strand breaks (DSB). As a result, EBV- transformed and cancer cells become dependent on other forms of DNA repair, in particular, the error-prone microhomology-mediated end-joining (MMEJ) type of repair. This creates a therapeutic vulnerability to synthetic lethal agents that would otherwise be non-toxic to cells with intact HR. PARP [poly (ADP-ribose) polymerase] inhibitors are among such synthetic lethal agents that target MMEJ. Indeed, we find that EBV-transformed and cancer cells are highly susceptible to MMEJ inhibitors that target PARP and the MMEJ-specific DNA polymerase, POLθ. Supporting this dependence on MMEJ, EBV-transformed cells exhibit genome-wide scars of MMEJ repair, and, EBV+ HIV-DLBCL display higher abundance of STAT3 and POLQ transcripts compared to EBV- tumors; POLQ encodes POLθ. Further, by multiomic analyses of several hundred cancer cell lines, we have identified a STAT3-related gene expression signature that points to a mechanistic link between STAT3 and reliance on MMEJ repair while predicting susceptibility to synthetic lethal therapies. We now propose to investigate how EBV uses the JAK-STAT3 pathway to reshape DNA repair and render EBV+ HIV-DLBCL vulnerable to synthetic lethal therapeutic targeting. Using cell lines, xenografts, and patient-derived EBV+ & EBV- HIV-DLBCL from the NCI AIDS and Cancer Specimen Resource (ACSR), we investigate the link between JAK-STAT3 pathway and DSB repair in EBV+ HIV-DLBCL (Aim 1) and synthetic-lethally exploit JAK- STAT3-dependent DNA repair deficiency to kill EBV+ HIV-DLBCL (Aim 2). These studies specifically address PAR-21-348 by identifying mechanisms and generating new paradigms to reveal how EBV contributes to NHL. In the long-term, these mechanistic insights will uncover novel vulnerabilities and enable the prediction of responses to synthetic lethal therapies to improve outcomes for EBV+ DLBCL in persons living with HIV.