HISTONE MODIFIERS IN ORAL KSHV INFECTION AND MALIGNANCIES

 KS常累及口腔，口腔KSHV感染是口腔KS发生和病毒传播所必需的。尽管接受了抗逆转录病毒治疗，但KS在艾滋病毒感染患者中仍然很常见。现有的抗病毒和抗癌治疗在消除KSHV持续感染和治疗KSHV诱发的癌症方面无效。由于KSHV的潜伏感染是其长期持续感染和KS发展所必需的，因此识别KSHV潜伏感染的关键因素有助于开发新的口腔KSHV持续感染和恶性肿瘤的治疗方法。我们开发了三种新的系统来应对这些挑战：1)KSHV诱导原代人骨髓间充质干细胞(MSCs)的细胞转化；2)KSHV在NOD/SCID IL2R-/-(人源化)小鼠的口腔持续感染；以及3)KSHV在原代人类口腔上皮细胞、牙龈MSCs和牙髓MSCs中的持续感染。使用这些模型，我们发现在潜伏的KSHV感染细胞中，细胞染色质和基因表达网络的广泛表观遗传重新编程。值得注意的是，靶向PrC2蛋白和sirtuins可以诱导潜伏感染KSHV的细胞大量死亡，包括转化的KSHV细胞，但对未感染细胞的细胞毒性最小。基于这些结果，我们的假设是，组蛋白修饰物介导了KSHV潜伏感染口腔细胞的存活，因此抑制这些靶点可以杀死潜伏感染KSHV的细胞，从而对口腔KSHV持续感染和KSHV诱导的癌症进行有效的治疗干预。我们建议确定KSHV在口腔细胞中潜伏感染所必需的组蛋白修饰物(目标1)；勾勒出组蛋白修饰物介导KSHV潜伏感染口腔细胞存活的机制(目标2)；以及通过靶向特定的组蛋白修饰物，在动物模型中明确KSHV持续感染和抑制KSHV诱导的口腔癌症的治疗作用(目标3)。这项拟议的项目具有重要意义，因为它将描绘口服KSHV持续感染和发病机制的基本组蛋白修饰物，并找到有效的抑制剂来治疗这些新的靶点。这一结果将为研究KSHV持续感染和诱发肿瘤的机制提供依据。这一结果也适用于其他口腔持续性病毒感染和病毒诱导的癌症。

 DESCRIPTION (provided by applicant): Kaposi's sarcoma (KS) is the most common cancer in AIDS patients associated with infection by Kaposi's sarcoma-associated herpesvirus (KSHV). KS is often involved with oral cavity, and oral KSHV infection is necessary for the development of oral KS and virus spread. Despite antiretroviral therapy, KS remains common among HIV-infected patients. Existing antiviral and anticancer therapies are ineffective for eliminating persistent KSHV infection and for treating KSHV-induced cancer. Because KSHV latent infection is necessary for its long-term persistent infection and for KS development, identificatio of factors essential for KSHV latent infection can lead to the development of novel therapeutic approaches for oral KSHV persistent infection and malignancies. We have developed three novel systems to address these challenges: 1) KSHV-induced cellular transformation of primary human bone marrow mesenchymal stem cells (MSCs), 2) KSHV persistent infection in the oral cavity in NOD/SCID IL2R-/- (NSG) "humanized" mice, and 3) KSHV persistent infection in primary human oral epithelial cells, gingiva MSCs and dental pulp MSCs. Using these models, we have found extensive epigenetic reprograming of cellular chromatins and gene expression networks in latent KSHV- infected cells. Furthermore, we have identified histone modifiers including polycomb repressive complex 2 (PRC2) proteins and class III histone deacetylases sirtuins as the critical factors for the survival of latent KSHV-infected cells. Significantly, targeting PRC2 proteins and sirtuins induce massive cell death of latent KSHV-infected cells including KSHV-transformed cells but have minimal cytotoxicity to uninfected cells. Based on these results, our hypothesis is that histone modifiers mediate the survival of latent KSHV-infected oral cells, and therefore inhibition of these targets can kill latent KSHV-infected cells resulting in effective therapeutic intervention for oral KSHV persistent infection and KSHV-induced cancer. We propose to identify the histone modifiers essential for KSHV latent infection in oral cells (Aim 1); delineate the mechanisms by which histone modifiers mediate the survival of latent KSHV infected oral cells (Aim 2); and therapeutically clear oral KSHV persistent infection and inhibit KSHV-induced oral cancer in animal models by targeting specific histone modifiers (Aim 3). The proposed project is significant because it will delineate the essential histone modifiers for oral KSHV persistent infection and pathogenesis, and identify effective inhibitors for therapeutic inhibition of these novel targets. The results will provide insights int the mechanisms of oral KSHV persistent infection and KSHV-induced oncogenesis. The outcomes can also be applied to other oral persistent viral infections and virus-induced cancer.