HISTONE MODIFIERS IN ORAL KSHV INFECTION AND MALIGNANCIES

 描述（由申请人提供）：卡波西肉瘤（KS）是艾滋病患者中与卡波西肉瘤相关疱疹病毒（KSHV）感染相关的最常见癌症。KS常累及口腔，口腔KSHV感染是KS发生发展和病毒传播的必要条件。尽管有抗逆转录病毒治疗，KS在艾滋病毒感染者中仍然很常见。现有的抗病毒和抗癌疗法对于消除持续性KSHV感染和治疗KSHV诱导的癌症是无效的。由于KSHV潜伏感染是其长期持续感染和KS发展所必需的，因此确定KSHV潜伏感染所必需的因素可以导致开发用于口腔KSHV持续感染和恶性肿瘤的新治疗方法。我们已经开发了三种新的系统来解决这些挑战：1）KSHV诱导的原代人骨髓间充质干细胞（MSC）的细胞转化，2）NOD/SCID IL 2 R β-/-（NSG）“人源化”小鼠口腔中的KSHV持续感染，和3）原代人口腔上皮细胞、牙龈MSC和牙髓MSC中的KSHV持续感染。利用这些模型，我们发现了潜伏的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编程。此外，我们已经确定了组蛋白修饰剂，包括polycomb抑制复合物2（PRC 2）蛋白和III类组蛋白脱乙酰酶sirtuins作为潜伏KSHV感染细胞存活的关键因素。值得注意的是，靶向PRC 2蛋白和sirtuins诱导潜伏的KSHV感染细胞（包括KSHV转化细胞）的大量细胞死亡，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，组蛋白修饰剂介导潜伏KSHV感染的口腔细胞的存活，因此抑制这些靶点可以杀死潜伏KSHV感染的细胞，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潜伏感染口腔细胞所必需的组蛋白修饰剂（目的1）;描述组蛋白修饰剂介导潜伏KSHV感染口腔细胞存活的机制（目的2）;通过靶向特定的组蛋白修饰剂治疗清除口腔KSHV持续感染并抑制动物模型中KSHV诱导的口腔癌（目的3）。该项目具有重要意义，因为它将描述口腔KSHV持续感染和发病机制的基本组蛋白修饰剂，并确定有效的抑制剂，用于这些新靶点的治疗抑制。本研究结果将为深入了解KSHV口腔持续感染和KSHV诱导肿瘤发生的机制提供理论依据。这些结果也可以应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.