Project description:Kaposi's sarcoma-associated herpesvirus (KSHV) is a human oncogenic virus, which maintains the persistent infection of the host by intermittently reactivating from latently infected cells to produce viral progenies. Here, we performed a comprehensive time course transcriptome analysis during KSHV reactivation in KSHV+ primary effusion B-cell lymphoma cells (PEL). For this we used a recombinant PEL cell line called TRExBCBL1-3xFLAG-RTA. The expression of the N-terminally 3xFLAG-tagged RTA was induced by adding 1 μg/ml doxycycline (Dox) to the medium. Total gene expression changes were identified in TRExBCBL1-3xFLAG-RTA cells at 0, 6, 12, and 24 hours post-induction (hpi).
Project description:Chromatin immunoprecipitation coupled with high-throughput sequencing (ChIP-seq) analysis was performed during Kaposi's sarcoma-associated herpesvirus (KSHV) reactivation in KSHV+ recombinant primary effusion B-cell lymphoma cells (PEL). RTA binding sites were identified genome-wide in a recombinant PEL cell line called TRExBCBL1-3xFLAG-RTA cells at 12 hours post-induction (hpi) of RTA expression.
Project description:Primary effusion lymphoma (PEL) is an aggressive subtype of non-Hodgkin lymphoma caused by Kaposi’s sarcoma-associated herpesvirus infection, which is most commonly seen in HIV-positive patients. Induction of HIV reactivation by external stimuli in the presence of highly active anti-retroviral therapy (HAART) has been examined for its efficacy to eradicate latently infected HIV. Similary, lytic activation of viruses from latently infected tumor cells with anti-cancer drugs represents an effective strategy of anti-neoplastic therapy, through the induction of oncolysis by viral replication, stimulation of immune responses to the viral lytic antigens, and intrinsic effects of cancer drugs. Here we examined the combination of PEP005 with epigenetic drugs as a rational therapeutic strategy to target both in AIDS-associated KSHV-mediated malignancies. JQ1, a bromodomain and extra terminal protein (BET) inhibitor, in combination with a FDA-approved drug, PEP005, not only robustly induced KSHV lytic replication, but also inhibited IL-6 and VEGF production from PEL cells. This combination has been proposed for use in reactivation of HIV from latently infected T-cells, and the same combination and dosage inhibited PEL growth in vitro and delayed tumor growth in a PEL xenograft tumor model. Downstream activation of NF-B by PEP005 combined with sequestration of bromodomain-containing protein 4 (BRD4) by JQ1 robustly increased occupancy of RNA polymerase II onto the KSHV genome. RNA-sequencing analysis further revealed cellular targets of PEP005, JQ1, and the synergistic effects of both. We suggest that the combination of PEP005 with JQ1 should be considered as a rational therapeutic approach for HIV-associated PEL.
Project description:Primary effusion lymphoma (PEL) is a rare B-cell malignancy that originates from B cells latently infected with Kaposi’s sarcoma-associated herpesvirus (KSHV, also known as human herpesvirus-8, HHV8). Our previous data indicated that several exogenous ceramide and dh-ceramide species, such as C18-Cer and dhC16-Cer, also displayed effective anti-cancer activities for KSHV+ PEL in vitro and in vivo. However, the underlying mechanisms for exogenous ceramide “killing” PEL cells still require further investigation, which will be helpful to better understand PEL pathogenesis and identify more potential therapeutic targets. In the current study, we used Illumina microarray to determine the altered gene profile in KSHV+ PEL cell-line, BCBL-1 exposure to dhC16-Cer.
Project description:The RIG-I like receptors (RLRs) RIG-I and MDA5 are cytosolic RNA helicases best characterized as restriction factors for RNA viruses. However, evidence suggests RLRs participate in innate immune recognition of other pathogens, including DNA viruses. Kaposi's sarcoma-associated herpesvirus (KSHV) is a human gammaherpesvirus and the etiological agent of Kaposi's sarcoma and primary effusion lymphoma (PEL). We demonstrate that RIG-I and MDA5 restrict KSHV lytic reactivation in PEL. By performing fRIP-Seq, we define the in vivo RLR substrates and demonstrate that RIG-I and MDA5-mediated restriction is facilitated exclusively by the recognition of host-derived RNAs.
Project description:iSLK.219 cells at 0, 6, 12, 24, and 48 hours post KSHV reactivation. Nucleosome occupancy plays a key role in regulating access to the eukaryotic genomes. Although various chromatin regulatory complexes are known to regulate nucleosome occupancy, the role of DNA sequence in this regulation remains unclear, particularly in mammals. To address this problem, we measured nucleosome distribution at high temporal resolution in human cells at hundreds of genes during the reactivation of KaposiM-bM-^@M-^Ys sarcoma-associated herpesvirus (KSHV). We show that nucleosome redistribution peaks at 24 hours post KSHV reactivation and that the nucleosomal redistributions are widespread and transient. To clarify the role of DNA sequence in these nucleosomal redistributions, we compared the genes with altered nucleosome distribution to a sequence-based computer model and in vitro assembled nucleosomes. We demonstrate that both the predicted model and the assembled nucleosome distributions are concordant with the majority of nucleosome redistributions at 24 hours post KSHV reactivation. We suggest a model in which loci are held in unfavorable chromatin architecture and M-bM-^@M-^\springM-bM-^@M-^] to a transient intermediate state directed by DNA sequence information. We propose that DNA sequence plays a more considerable role in the regulation of nucleosome positions than was previously appreciated. The surprising findings that nucleosome redistributions are widespread, transient, and DNA-directed shift the current perspective regarding regulation of nucleosome distribution in humans. iSLK.219 cells at 0, 6, 12, 24, and 48 hours post KSHV reactivation.
Project description:Enhancers play indispensable roles in cell proliferation and survival through spatiotemporally regulating gene transcription. In addition, active enhancers and super-enhancers often produce noncoding enhancer RNAs (eRNAs) that precisely control RNA polymerase II activity. Kaposi’s sarcoma-associated herpesvirus (KSHV) is a human oncogenic gamma-2 herpesvirus that causes Kaposi’s sarcoma and lymphoproliferative diseases of B-cell origin such as primary effusion lymphoma (PEL). It is well characterized that KSHV utilizes host epigenetic and nuclear machineries to control the switch between two life cycles, latency and lytic replication. However, how KSHV impacts the host epigenome at different stages of viral life cycle is not well understood. Using the analysis of global run-on sequencing (GRO-seq) and chromatin-immunoprecipitation sequencing (ChIP-seq), we profiled the dynamics of host transcriptional regulatory elements during latency and lytic replication of KSHV-infected PEL cells. This study showed that a number of critical host genes for KSHV latency, including MYC proto-oncogene, were under the control of super-enhancers and eRNAs that were globally repressed upon viral reactivation. A combination of circular chromosome conformation capture combined with sequencing (4C-seq), GRO-seq and ChIP-seq indicated that the eRNA-expressing super-enhance regions were located at downstream of the MYC gene in KSHV-infected PELs. Treatment of an epigenetic drug to block enhancer function or shRNA-mediated depletion of the eRNA expression significantly reduced MYC mRNA expression in KSHV-infected PELs. Finally, while cellular IRF4 acted upon the eRNAs and super-enhancers for MYC expression during latency, the KSHV viral IRF4 repressed cellular IRF4 expression upon reactivation, decreasing MYC expression and thereby, facilitating lytic replication. Taken together, these data suggest that KSHV acts as an epigenetic driver that modifies host epigenomic status by effectively regulating enhancer function upon reactivation.
Project description:Primary effusion lymphoma (PEL) is an aggressive subtype of non-Hodgkin lymphoma caused by Kaposi's sarcoma-associated herpesvirus (KSHV) infection. Currently, treatment options for patients with PEL are limited. Oncolytic viruses have been engineered as anticancer agents and have recently shown increased therapeutic promise. Similarly, lytic activation of endogenous viruses from latently infected tumor cells can also be applied as a cancer therapy. In theory, such a therapeutic strategy would induce oncolysis by viral replication, while simultaneously stimulating an immune response to viral lytic cycle antigens. We examined the combination of the FDA-approved drug ingenol-3-angelate (PEP005) with epigenetic drugs as a rational therapeutic approach for KSHV-mediated malignancies. JQ1, a bromodomain and extra terminal (BET) protein inhibitor, in combination with PEP005, not only robustly induced KSHV lytic replication, but also inhibited IL6 production from PEL cells. Using the dosages of these agents that was found to be effective in reactivating HIV (as a means to clear latent virus with highly active antiretroviral therapy), we were able to inhibit PEL growth in vitro and delay tumor growth in a PEL xenograft tumor model. KSHV reactivation was mediated by activation of NF-kB pathway by PEP005, which led to increased occupancy of RNA polymerase II onto the KSHV 33 genome. RNA-sequencing analysis further revealed cellular targets of PEP005, JQ1, and the synergistic effects of both. Thus, combination of PEP005 with a BET inhibitor may be considered as a rational therapeutic approach for the treatment of PEL.
Project description:Primari effusion lymphoma are (PEL) patient-derived transformed B-cells harboring latent Kaposi's sarcoma-associated herpesvirus (KSHV). The treatment of PEL cells with valproic acid (VA) leads to reactivation of KSHV and viral lytic replication. The aim of this project is to evaluate the effect of KSHV lytic infection on expression of the host transcriptome.