Kaposi's sarcoma (KS) remains as an important cancer in AIDS patients despite anti-retroviral therapy. It is the most common cancer in both HIV-positive and -negative populations in many African countries. Kaposi's sarcoma-associated herpesvirus (KSHV) lytic replication is essential for KS development, and is an effective prognostic marker for KS. In the current funding period, we have identified ERK, p38 and JNK mitogen- activated protein kinase (MAPK) pathways as the essential mediators of KSHV lytic replication. Furthermore, we have shown that reactive oxygen species (ROS) hydrogen peroxide is essential and sufficient for activating KSHV lytic replication. Significantly, ROS scavengers such as antioxidant N-acetyl-L-cysteine (NAC) inhibit KSHV replication in vitro and in a primary effusion lymphoma (PEL) mouse model, and slows the progression of lymphoma. The objective of this application is to further dissect the molecular mechanism by which MAPK pathways and ROS mediate KSHV lytic replication induced by physiological triggers including inflammatory cytokines and hypoxia, and examine the preventive and therapeutic effect of targeting ROS for inhibiting KSHV replication and KS development. The central hypothesis is that inflammatory cytokines and hypoxia activate MAPK pathways and induce ROS, resulting in the activation of KSHV lytic replication, and as a result, ROS scavengers can effectively inhibit KSHV lytic replication and KS development. We have recently developed a novel KSHV-induced KS model, which is particularly useful for preclinical testing of novel agents targeting KSHV lytic replication and KS development. We will test the hypothesis by performing the following four Specific Aims: 1) To examine the individual and combined effects of hypoxia and inflammatory cytokines on activating KSHV lytic replication, and the involvement of ROS and MAPK pathways;2) To define the molecular interactions of ROS and MAPK pathways that mediate KSHV lytic replication induced by hypoxia and inflammation cytokines;3) To define KSHV epigenetic signatures in MAPK pathways-mediated viral lytic replication induced by ROS, inflammation cytokines and hypoxia;and 4) To examine the preventive and therapeutic effect of ROS scavengers on KSHV lytic replication and KS development in a novel KSHV-induced KS model. The proposed project is highly significant because it will define the molecular basis underlying KSHV lytic replication induced by physiological triggers, and identify novel intervention targets for KSHV- induced malignancies. It will employ innovative contemporary technologies and a novel KSHV-induced KS model. We expect to illustrate an essential role of ROS and MAPK pathways in KSHV lytic replication, and demonstrate efficient inhibition of KSHV lytic replication and KS development by ROS scavenger NAC, which should establish the basis for future clinical trials for KSHV-induced malignancies in HIV patients. Because of their wide availability and affordability, NAC and other antioxidants are attractive agents for KSHV-associated malignancies, particularly in underserved populations and in Africa.

Public Health Relevance

Kaposi's sarcoma, caused by infection of Kaposi's sarcoma-associated herpesvirus (KSHV), is a common malignancy in AIDS patients in US and worldwide, inflicting morbidity and mortality to the society. This project will investigate the mechanism of KSHV replication and Kaposi's sarcoma development, which can lead to the identification potential targets for the prevention and treatment of this disease.

National Institute of Health (NIH)
National Cancer Institute (NCI)
Research Project (R01)
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AIDS-associated Opportunistic Infections and Cancer Study Section (AOIC)
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Read-Connole, Elizabeth Lee
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University of Southern California
Schools of Medicine
Los Angeles
United States
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Tan, Brandon; Liu, Hui; Zhang, Songyao et al. (2018) Viral and cellular N6-methyladenosine and N6,2'-O-dimethyladenosine epitranscriptomes in the KSHV life cycle. Nat Microbiol 3:108-120
Gruffaz, Marion; Zhou, Shenghua; Vasan, Karthik et al. (2018) Repurposing Cytarabine for Treating Primary Effusion Lymphoma by Targeting Kaposi's Sarcoma-Associated Herpesvirus Latent and Lytic Replications. MBio 9:
Cheng, Fan; Ramos da Silva, Suzane; Huang, I-Chueh et al. (2018) Suppression of Zika Virus Infection and Replication in Endothelial Cells and Astrocytes by PKA Inhibitor PKI 14-22. J Virol 92:
Gruffaz, Marion; Vasan, Karthik; Tan, Brandon et al. (2017) TLR4-Mediated Inflammation Promotes KSHV-Induced Cellular Transformation and Tumorigenesis by Activating the STAT3 Pathway. Cancer Res 77:7094-7108
Zhu, Ying; Li, Tingting; Ramos da Silva, Suzane et al. (2017) A Critical Role of Glutamine and Asparagine ?-Nitrogen in Nucleotide Biosynthesis in Cancer Cells Hijacked by an Oncogenic Virus. MBio 8:
Jeon, Hyungtaek; Yoo, Seung-Min; Choi, Hyo Sun et al. (2017) Extracellular vesicles from KSHV-infected endothelial cells activate the complement system. Oncotarget 8:99841-99860
He, Meilan; Tan, Brandon; Vasan, Karthik et al. (2017) SIRT1 and AMPK pathways are essential for the proliferation and survival of primary effusion lymphoma cells. J Pathol 242:309-321
Yuan, Hongfeng; Tan, Brandon; Gao, Shou-Jiang (2017) Tenovin-6 impairs autophagy by inhibiting autophagic flux. Cell Death Dis 8:e2608
Li, W; Hu, M; Wang, C et al. (2017) A viral microRNA downregulates metastasis suppressor CD82 and induces cell invasion and angiogenesis by activating the c-Met signaling. Oncogene 36:5407-5420
Yuan, Hongfeng; He, Meilan; Cheng, Fan et al. (2017) Tenovin-6 inhibits proliferation and survival of diffuse large B-cell lymphoma cells by blocking autophagy. Oncotarget 8:14912-14924

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