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

项目总结 弥漫性大B细胞淋巴瘤(DLBCL)是最常见的非霍奇金淋巴瘤(NHL)，具有高度的 尽管服用了抗逆转录病毒药物，但侵袭性仍然是活人癌症相关死亡的主要原因 艾滋病毒携带者。值得注意的是，高达90%的HIV-DLBCL对致癌的Epstein-Barr病毒(EBV)呈阳性。因此， 了解EBV是如何导致癌症的，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修复还没有被探索 区域。我们对EBV-癌细胞和EBV转化的人B细胞(淋巴母细胞系)的研究，后者 在免疫抑制的宿主中，EBV驱动的淋巴瘤的一个重要模型，聚集在STAT3上。一个 癌蛋白STAT3在癌症中经常被激活。多项研究也表明，EBV+HIV-DLBCL 在Janus Kinase(JAK)-STAT3通路中经常表现出激活突变。我们发现EB病毒 激活STAT3以绕过S阶段的检查站屏障，从而确保细胞增殖，但在 过程中，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，特别是容易出错的 微同源介导的末端连接(MMEJ)修复类型。这造成了一种治疗上的脆弱性，即合成 致命剂，否则对HR完好的细胞是无毒的。聚腺苷二磷酸核糖聚合酶 抑制剂是以MMEJ为靶点的合成致死剂之一。事实上，我们发现EBV转化的和 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， 波尔θ。支持这种对MMEJ的依赖，EBV转化的细胞显示出MMEJ的全基因组疤痕 与EBV-DLBCL相比，EBV+HIV-DLBCL的STAT3和POLQ转录本丰度更高 肿瘤；POLQ编码POLθ。此外，通过对数百种癌细胞株的多组学分析，我们有 发现了一个与STAT3相关的基因表达特征，表明STAT3和STAT3之间存在机械联系 依赖MMEJ修复，同时预测对合成致命疗法的易感性。 我们现在建议研究EBV如何使用JAK-STAT3途径重塑DNA修复和呈现EBV+ HIV-DLBCL易受合成致命治疗靶向的影响。使用细胞系、异种移植和患者来源的 EBV+和EBV-HIV-DLBCL来自美国国立卫生研究院艾滋病和癌症标本资源(ACSR)，我们调查了两者之间的联系 EBV+HIV-DLBCL中JAK-STAT3通路与DSB修复之间的关系及JAK-STAT3的合成致死性开发 依赖STAT3的DNA修复缺陷以杀死EBV+HIV-DLBCL(目标2)。 这些研究具体针对PAR-21-348，确定机制并产生新的范例，以 揭示EBV对非霍奇金淋巴瘤的贡献。从长远来看，这些机械性的洞察力将揭示新的漏洞 并能够预测对合成致命疗法的反应，以改善EBV+DLBCL的预后 艾滋病毒携带者。

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.