Regulation of the Tumor Microenvironment by KSHV

项目摘要/摘要 卡波西肉瘤(KS)仍然是HIV/AIDS患者最常见的肿瘤，并累及 口腔肿瘤是该肿瘤最常见的临床表现之一。卡波西‘s 肉瘤相关疱疹病毒(KSHV)复制和持续感染靶细胞起重要作用 在KS发病机制中的作用。氨基酸膜转运蛋白亚基XCT维持细胞内 谷胱甘肽储存以提高产生活性氮种(RNS)的细胞的生存，而XCT是 最近被确定为KSHV的融合进入受体(Kaleeba和Berger，Science，2006)。一批 细胞内和细胞外的触发器调节XCT的表达，包括通过 转录调节因子和RNS对正转录调节因子的激活。我们已经决定 最近，XCT在KS皮损和循环单核细胞中的多种细胞类型中表达 来自HIV感染患者的细胞，来自KSHV/HIV混合感染患者的细胞表现出最高的XCT 表情。然而，目前尚不清楚KSHV本身是否调节XCT的表达以促进KSHV 在当地环境中的感染和持久性。KSHV感染KS皮损内的巨噬细胞，并且 巨噬细胞是RNS的主要来源。使用一种新的巨噬细胞培养系统，我们的初步 数据表明，KSHV的microRNA抑制了XCT表达的负转录调节因子Bach-1， KSHV可诱导巨噬细胞分泌RNS。根据这些初步数据，我们 假设KSHV通过上调XCT来促进其自身在本地环境中的持久性 通过旁分泌和自分泌机制表达以及靶向XCT调控 途径可减少KSHV在微环境中的感染和持久性。要解决这个问题 假设，我们提出了两个独立的目标：1)确定机制和功能结果 KSHV对XCT的调控；2)确定KSHV感染与XCT之间的临床关系 KS高危HIV感染者的表达和RNS的产生。通过这些努力，我们 希望通过靶向治疗KS为开发新的治疗策略提供框架 XCT和减少KSHV在肿瘤微环境中的感染和持久性。

PROJECT SUMMARY/ABSTRACT Kaposi's sarcoma (KS) remains the most common tumor arising in patients with HIV/AIDS, and involvement of the oral cavity represents one of the most common clinical manifestations of this tumor. Kaposi's sarcoma-associated herpesvirus (KSHV) replication and ongoing infection of target cells plays an important role in KS pathogenesis. An amino acid membrane transport protein subunit, xCT, maintains intracellular glutathione stores to enhance the survival of cells producing reactive nitrogen species (RNS), and xCT was recently identified as a fusion-entry receptor for KSHV (Kaleeba and Berger, Science, 2006). A number of intracellular and extracellular triggers regulate xCT expression, including binding of the xCT promoter by transcription regulators and the activation of positive transcription regulators by RNS. We have determined recently that xCT is expressed by multiple cell types within KS lesions and circulating mononuclear cells from HIV-infected patients, with cells from KSHV/HIV co-infected patients exhibiting the highest xCT expression. However, it is unknown whether KSHV itself regulates xCT expression to promote KSHV infection and persistence in the local environment. KSHV infects macrophages within KS lesions, and macrophages are a principal source of RNS. Using a novel macrophage cell culture system, our preliminary data suggest that KSHV microRNA suppress BACH-1, a negative transcription regulator of xCT expression, and that KSHV induces RNS secretion by macrophages. Based on these preliminary data, we hypothesize that KSHV promotes its own persistence in the local environment by upregulating xCT expression through both paracrine and autocrine mechanisms, and that targeting xCT regulatory pathways reduces KSHV infection and persistence in the microenvironment. To address this hypothesis, we propose two independent aims: 1) to determine mechanisms and functional outcomes for xCT regulation by KSHV; and 2) to determine clinical relationships between KSHV infection, xCT expression and RNS production in HIV-infected patients at greatest risk for KS. Through these efforts, we hope to provide the framework for developing novel therapeutic strategies for KS through the targeting of xCT and the reduction of KSHV infection and persistence within the tumor microenvironment.