Department of Microbiology, University of Washington, Seattle, WA 98109.
Department of Microbiology, University of Washington, Seattle, WA 98109
Proc Natl Acad Sci U S A. 2020 Nov 10;117(45):28384-28392. doi: 10.1073/pnas.2011645117. Epub 2020 Oct 29.
Kaposi's sarcoma-associated herpesvirus (KSHV) is the etiologic agent of Kaposi's sarcoma (KS) and primary effusion lymphoma (PEL). The main proliferating component of KS tumors is a cell of endothelial origin termed the spindle cell. Spindle cells are predominantly latently infected with only a small percentage of cells undergoing viral replication. As there is no direct treatment for latent KSHV, identification of host vulnerabilities in latently infected endothelial cells could be exploited to inhibit KSHV-associated tumor cells. Using a pooled CRISPR-Cas9 lentivirus library, we identified host factors that are essential for the survival or proliferation of latently infected endothelial cells in culture, but not their uninfected counterparts. Among the many host genes identified, there was an enrichment in genes localizing to the mitochondria, including genes involved in mitochondrial translation. Antibiotics that inhibit bacterial and mitochondrial translation specifically inhibited the expansion of latently infected endothelial cells and led to increased cell death in patient-derived PEL cell lines. Direct inhibition of mitochondrial respiration or ablation of mitochondrial genomes leads to increased death in latently infected cells. KSHV latent infection decreases mitochondrial numbers, but there are increases in mitochondrial size, genome copy number, and transcript levels. We found that multiple gene products of the latent locus localize to the mitochondria. During latent infection, KSHV significantly alters mitochondrial biology, leading to enhanced sensitivity to inhibition of mitochondrial respiration, which provides a potential therapeutic avenue for KSHV-associated cancers.
卡波氏肉瘤相关疱疹病毒（KSHV）是卡波氏肉瘤（KS）和原发性渗出性淋巴瘤（PEL）的病原体。KS 肿瘤的主要增殖成分是一种内皮细胞来源的细胞，称为梭形细胞。梭形细胞主要潜伏感染，只有一小部分细胞发生病毒复制。由于没有针对潜伏 KSHV 的直接治疗方法，因此可以利用潜伏感染内皮细胞中的宿主弱点来抑制与 KSHV 相关的肿瘤细胞。我们使用了一个汇集的 CRISPR-Cas9 慢病毒文库，鉴定了宿主因子，这些因子对于培养中潜伏感染的内皮细胞的存活或增殖是必需的，但对于未感染的细胞则不是必需的。在鉴定出的许多宿主基因中，与线粒体定位相关的基因富集，包括参与线粒体翻译的基因。特异性抑制细菌和线粒体翻译的抗生素可特异性抑制潜伏感染的内皮细胞的扩增，并导致患者来源的 PEL 细胞系中的细胞死亡增加。直接抑制线粒体呼吸或破坏线粒体基因组会导致潜伏感染细胞死亡增加。KSHV 潜伏感染会减少线粒体数量，但会增加线粒体大小、基因组拷贝数和转录水平。我们发现潜伏基因座的多个基因产物定位于线粒体。在潜伏感染期间，KSHV 会显著改变线粒体生物学，导致对线粒体呼吸抑制的敏感性增加，这为 KSHV 相关癌症提供了一种潜在的治疗途径。
