High-throughput sequencing analysis of a “hit and run” cell and animal model of KSHV tumorigenesis. [RNA-Seq]
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ABSTRACT: Kaposi's sarcoma (KS), is an AIDS-associated neoplasm caused by the KS herpesvirus (KSHV). A mouse model of KSHV-dependent tumorigenicity, allowed us to induce KSHV viral-episome loss following tumor development to test the plausibility of “hit and run” mechanism by KSHV. RNA-seq-transcriptome analysis and CpG-methylation were performed on KSHV positive cells, KSHV positive tumors and tumors that developed following viral-episome loss. During KSHV tumorigenesis, hypo-methylation was detected of oncogenic and differentiation pathways. In contrast, during tumorigenesis following KSHV-episome loss, a tendency towards hyper-methylation was detected. We found the same set of innate-immunity related mutations undetected in KSHV-infected cells but present in all KSHV-positive tumors, indicating that pre-existing host mutations that provide an in vivo growth advantage are clonally-selected and contribute to KSHV-tumorigenesis. We found de novo mutations related to cell proliferation that, together with the PDGFRAD842V, were responsible for driving tumorigenesis in absence of the KSHV-episomes. Virally-induced irreversible genetic and epigenetic oncogenic alteration supports the possibility of “hit and run” KSHV-sarcomagenesis consistent with the existence of LANA-negative spindle-cells in KS lesions.
Project description:Kaposi's sarcoma (KS), is an AIDS-associated neoplasm caused by the KS herpesvirus (KSHV/ HHV-8). KSHV-sarcomagenesis is the consequence of oncogenic viral gene expression as well as host genetic and epigenetic alterations. Although KSHV is invariably found in all KS lesions, the percentage of KSHV-infected (LANA+) spindle-cells of the lesion is variable, suggesting the existence of paracrine oncogenic mechanisms and/or spindle cells that have lost KSHV. A mouse model of KSHVBac36-driven tumorigenesis allowed us to induce KSHV-episome loss before and after tumor development. Although cells that lose the KSHV episome prior to tumor formation lose their tumorigenicity, explanted KSHV positive tumor cells that lost the KSHV episome remained tumorigenic. This pointed to the existence of virally-induced irreversible oncogenic alterations occurring during KSHV-tumor formation that support the possibility of hit and run viral sarcomagenesis. RNA sequencing and CpG-methylation analysis were performed on KSHV positive and negative cells, KSHV positive and KSHV negative tumors that developed following KSHV-episome loss from explanted tumor cells. When KSHV positive cells form KSHV-driven tumors, along with viral-gene upregulation there is a tendency for hypo-methylation in genes from oncogenic and differentiation pathways. In contrast, KSHV-negative tumors formed after KSHV-episome loss, show a tendency towards gene hyper-methylation when compared to KSHV-positive tumors. Regarding occurrence of host-mutations, we found the same set of innate-immunity related mutations undetected in KSHV-infected cells but present in all KSHV positive tumors, indicating that pre-existing host mutations that provide an in vivo growth advantage are clonally-selected and contribute to KSHV-tumorigenesis. In addition, KSHV negative tumors display de novo mutations related to cell proliferation that, together with the PDGFRAD842V, were responsible for driving tumorigenesis in absence of the KSHV-episomes. KSHV-induced irreversible genetic and epigenetic oncogenic alterations support the possibility of “hit and run” KSHV-sarcomagenesis consistent with the presence of LANA-negative spindle-cells in KS lesions.
Project description:Kaposi’s Sarcoma (KS) is a heterogenous, multifocal vascular malignancy caused by the human herpesvirus 8 (HHV8), also known as Kaposi’s Sarcoma-Associated Herpesvirus (KSHV). Here, we show that KS lesions express iNOS/NOS2 broadly throughout KS lesions, with enrichment in LANA positive spindle cells. The iNOS byproduct 3-nitrotyrosine is also enriched in LANA positive tumor cells and colocalizes with a fraction of LANA-nuclear bodies. We show that iNOS is highly expressed in the L1T3 tumor model of KS. iNOS expression correlated with KSHV lytic cycle gene expression, which was elevated in late-stage tumors (>4 weeks) but to a lesser degree in early stage (1 week) xenografts. Further, we show that L1T3 tumor growth is sensitive to an inhibitor of nitric oxide, L-NMMA. These finding suggest that iNOS is expressed in KSHV infected endothelial-transformed tumor cells in KS, that iNOS expression depends on tumor microenvironment stress conditions, and that iNOS enzymatic activity contributes to KS tumor growth.
Project description:Transfection of a Kaposi's sarcoma (KS) herpesvirus (KSHV) Bacterial Artificial Chromosome (KSHVBac36) into mouse bone marrow endothelial lineage cells generated a cell (mECK36) that induced KS-like tumors in mice. mECK36 formed KSHV-harboring vascularized spindle-cell sarcomas that were LANA+ and displayed a KSHV and host transcriptomes reminiscent of KS tumors. Experiment Overall Design: There are three biological replicates per sample. Tumors (mKS) were compared the the human KS signature. mECK36 and mEC-V were compared to putative BM lineage cells.
Project description:Transfection of a Kaposi's sarcoma (KS) herpesvirus (KSHV) Bacterial Artificial Chromosome (KSHVBac36) into mouse bone marrow endothelial lineage cells generated a cell (mECK36) that induced KS-like tumors in mice. mECK36 formed KSHV-harboring vascularized spindle-cell sarcomas that were LANA+ and displayed a KSHV and host transcriptomes reminiscent of KS tumors. Keywords: Cell type comparison
Project description:Kaposi's sarcoma (KS) may derive from Kaposi's Sarcoma Herpesvirus (KSHV)-infected human Mesenchymal Stem Cells (hMSCs) that migrate to sites characterized by inflammation and angiogenesis, promoting the initiation of KS. By analyzing the RNA sequences of KSHV-infected primary hMSCs, we have identified specific cell subpopulations, mechanisms, and conditions involved in the initial stages of KSHV-induced transformation and reprogramming of hMSCs into KS progenitor cells. Under pro-angiogenic environmental conditions, KSHV can reprogram hMSCs to exhibit gene expression profiles more similar to KS tumors, activating cell cycle progression, cytokine signaling pathways, and endothelial differentiation indicating the involvement of KSHV infection in inducing the Mesenchymal-to-Endothelial (MEndT) transition of hMSCs. This finding underscores the significance of this condition in facilitating KSHV-induced proliferation and reprogramming of hMSCs towards MEndT and closer to KS gene expression profiles, providing further evidence of these cell subpopulations as precursors of KS cells that thrive in a pro-angiogenic environment.
Project description:Purpose: To characterize genome-wide microRNA (miRNA) expression profiles in the context of Kaposi’s sarcoma-associated herpesvirus (KSHV)-induced oncogenesis using isogenic cell lines for a Kaposi's sarcoma (KS) xenograft model: KSHV-infected human endothelial cells (LTC) that form tumors with properties closely resembling KS lesions in nude mice and uninfected parental (TIVE) cells. Methods: miRNA expression profiles of LTC and TIVE cells were generated by deep sequencing using Illumina HiSeq 2500. The mappable reads were aligned to the human genome and miRBase using Bowtie. Results: We show, through global cellular miRNA transcriptome analysis, that KSHV infection has a profound impact on the host miRNA expression landscape, up-regulating multiple miRNAs with oncogenic roles while down-regulating many tumor suppressive miRNAs, thereby contributing to KS oncogenesis. In particular, we identify miR-127-3p as one of the most significantly down-regulated miRNAs in LTC and restoring this miRNA inhibits KSHV-induced transformation, proliferation and tumorigenesis. Conclusions: This study provides a detailed analysis of the cellular miRNA transcriptome in LTC and TIVE cells using small RNA sequencing technology. We identify significant dysregulation of cellular miRNAs with important oncogenic or tumor-suppressive functions that may be physiologically relevant to KSHV oncogenesis. Moreover, our results identify a previously unrecognized tumor suppressor function for miR-127-3p in KS, indicating that its restoration offers potential as a therapeutic intervention for KS.
Project description:Kaposi’s sarcoma-associated herpesvirus (KSHV) is the causative agent of Kaposi’s sarcoma (KS) and multiple types of B cellmalignancies. Emerging evidence demonstrates that KSHV reprograms host-cell central carbon metabolic pathways, which contributesto viral persistence and tumorigenesis. However, the mechanisms underlying KSHV-mediated metabolic reprogramming remain poorlyunderstood. Carbamoyl-phosphate synthetase 2, aspartate transcarbamoylase, and dihydroorotase (CAD) is a key enzyme of the denovo pyrimidine synthesis, and was recently identified to deamidate the NF-κB subunit RelA to promote aerobic glycolysis and cellproliferation. Here we report that KSHV infection exploits CAD for nucleotide synthesis and glycolysis. Mechanistically, KSHV vCyclin binds to and hijacks cyclin-dependent kinase CDK6 to phosphorylate Ser-1900 on CAD, thereby activating CAD-mediatedpyrimidine synthesis and RelA-deamidation-mediated glycolytic reprogramming. Correspondingly, genetic depletion orpharmacological inhibition of CDK6 and CAD potently impeded KSHV lytic replication and thwarted tumorigenesis of primaryeffusion lymphoma (PEL) cells in vitro and in vivo. Altogether, our work defines a viral metabolic reprogramming mechanismunderpinning KSHV oncogenesis, which may spur the development of new strategies to treat KSHV-associated malignancies and otherdiseases.
Project description:The Kaposiâs Sarcoma-associated Herpesvirus (KSHV) is the etiologic agent of several human cancers, including Kaposiâs Sarcoma (KS), which preferentially arise in immunocompromised patients but lack of effective therapeutic options. We have previously shown that KSHV or viral protein LANA can upregulate the glycoprotein CD147 (Emmprin) to induce primary endothelial cell invasiveness, which also requires PI3K/Akt and MAPK activation of VEGF production. In the current study, we first time identify the global network controlled by CD147 in KSHV-infected endothelial cells using Illumina microarray analysis. Among these downstream genes, ADAMTS1 and 9, two specific metalloproteases are strongly expressed in AIDS-KS tissues and contributed to KSHV-infected cell invasiveness through regulation of related cytokines production and respective receptors expression. By using a nude mice KS-like model, we found that targeting CD147 and downstream ADAMTSs proteins significantly suppressed KSHV-related tumorigenesis in vivo, which is potentially through impairing extracellular matrix (ECM) formation in tumor microenvironment. Taken together, we think that targeting CD147 and related proteins may represent a promising therapeutic strategy against KSHV-related malignancies. HUVEC cells were infected by KSHV or transduced by a CD147 recombinant adenoviral vector and the gene expression signature was compared to respective controls
Project description:Kaposi’s sarcoma (KS) is an AIDS-defining cancer caused by the KS-associated herpesvirus (KSHV). Unanswered questions regarding KS are its cellular ontology and the conditions conducive to viral oncogenesis. We identify PDGFRA(+)/SCA-1(+) bone marrow-derived mesenchymal stem cells (Pα(+)S MSCs) as KS spindle-cell progenitors and found that pro-angiogenic environmental conditions typical of KS are critical for KSHV sarcomagenesis. This is because growth in KS-like conditions generates a de-repressed KSHV epigenome allowing oncogenic KSHV gene expression in infected Pα(+)S MSCs. Furthermore, these growth conditions allow KSHV-infected Pα(+)S MSCs to overcome KSHV-driven oncogene-induced senescence and cell cycle arrest via a PDGFRA-signaling mechanism; thus identifying PDGFRA not only as a phenotypic determinant for KS-progenitors but also as a critical enabler for viral oncogenesis.
Project description:Kaposi’s sarcoma (KS) is an AIDS-defining cancer caused by the KS-associated herpesvirus (KSHV). Unanswered questions regarding KS are its cellular ontology and the conditions conducive to viral oncogenesis. We identify PDGFRA(+)/SCA-1(+) bone marrow-derived mesenchymal stem cells (Pα(+)S MSCs) as KS spindle-cell progenitors and found that pro-angiogenic environmental conditions typical of KS are critical for KSHV sarcomagenesis. This is because growth in KS-like conditions generates a de-repressed KSHV epigenome allowing oncogenic KSHV gene expression in infected Pα(+)S MSCs. Furthermore, these growth conditions allow KSHV-infected Pα(+)S MSCs to overcome KSHV-driven oncogene-induced senescence and cell cycle arrest via a PDGFRA-signaling mechanism; thus identifying PDGFRA not only as a phenotypic determinant for KS-progenitors but also as a critical enabler for viral oncogenesis.