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Inflammation triggered by innate immunity promotes carcinogenesis in cancer. Kaposi's sarcoma (KS), a hyperproliferative and inflammatory tumor caused by Kaposi's sarcoma-associated herpesvirus (KSHV) infection, is the most common cancer in AIDS patients. KSHV infection sensitizes cells to pathogen-associated molecular patterns (PAMPs). We examined the role of Pseudomonas aeruginosa , an opportunistic bacterium that can affect AIDS patients, in inflammation and cell proliferation of KSHV-transformed cells. P. aeruginosa stimulation increased cell proliferation and efficiency of colony formation in soft agar of KSHV-transformed rat primary mesenchymal precursor (KMM) cells but had no significant effect on the untransformed (MM) cells. P. aeruginosa stimulation also increased cell proliferation of KSHV-infected human B cells, BJAB, but not the uninfected cells. Mechanistically, P. aeruginosa stimulation resulted in increased inflammatory cytokines and activation of p38, ERK1/2, and JNK mitogen-activated protein kinase (MAPK) pathways in KMM cells while having no obvious effect on MM cells. P. aeruginosa induction of inflammation and MAPKs was observed with and without inhibition of the Toll-like receptor 4 (TLR4) pathway, while a flagellin-deleted mutant of P. aeruginosa required a functional TLR4 pathway to induce inflammation and MAPKs. Furthermore, treatment with either lipopolysaccharide (LPS) or flagellin alone was sufficient to induce inflammatory cytokines, activate MAPKs, and increase cell proliferation and efficiency of colony formation in soft agar of KMM cells. These results demonstrate that both LPS and flagellin are PAMPs that contribute to P. aeruginosa induction of inflammation in KSHV-transformed cells. Because AIDS-KS patients are susceptible to P. aeruginosa infection, our work highlights the preventive and therapeutic potential of targeting P. aeruginosa infection in these patients. IMPORTANCE Kaposi's sarcoma (KS), caused by infection with Kaposi's sarcoma-associated herpesvirus (KSHV), is one of the most common cancers in AIDS patients. KS is a highly inflammatory tumor, but how KSHV infection induces inflammation remains unclear. We have previously shown that KSHV infection upregulates Toll-like receptor 4 (TLR4), sensitizing cells to lipopolysaccharide (LPS) and Escherichia coli In the current study, we examined the role of Pseudomonas aeruginosa , an opportunistic bacterium that can affect AIDS patients, in inflammation and cell proliferation of KSHV-transformed cells. P. aeruginosa stimulation increased cell proliferation, inflammatory cytokines, and activation of growth and survival pathways in KSHV-transformed cells through two pathogen-associated molecular patterns, LPS and flagellin. Because AIDS-KS patients are susceptible to P. aeruginosa infection, our work highlights the preventive and therapeutic potential of targeting P. aeruginosa infection in these patients., (Copyright © 2020 Markazi et al.)

Kaposi's sarcoma (KS), caused by Kaposi's sarcoma-associated herpesvirus (KSHV), is a highly angioproliferative disseminated tumor of endothelial cells commonly found in AIDS patients. We have recently shown that KSHV-encoded viral interferon regulatory factor 1 (vIRF1) mediates KSHV-induced cell motility (PLoS Pathog. 2019 Jan 30;15(1):e1007578). However, the role of vIRF1 in KSHV-induced cellular transformation and angiogenesis remains unknown. Here, we show that vIRF1 promotes angiogenesis by upregulating sperm associated antigen 9 (SPAG9) using two in vivo angiogenesis models including the chick chorioallantoic membrane assay (CAM) and the matrigel plug angiogenesis assay in mice. Mechanistically, vIRF1 interacts with transcription factor Lef1 to promote SPAG9 transcription. vIRF1-induced SPAG9 promotes the interaction of mitogen-activated protein kinase kinase 4 (MKK4) with JNK1/2 to increase their phosphorylation, resulting in enhanced VEGFA expression, angiogenesis, cell proliferation and migration. Finally, genetic deletion of ORF-K9 from KSHV genome abolishes KSHV-induced cellular transformation and impairs angiogenesis. Our results reveal that vIRF1 transcriptionally activates SPAG9 expression to promote angiogenesis and tumorigenesis via activating JNK/VEGFA signaling. These novel findings define the mechanism of KSHV induction of the SPAG9/JNK/VEGFA pathway and establish the scientific basis for targeting this pathway for treating KSHV-associated cancers., Competing Interests: The authors have declared that no competing interests exist.

Background: Endemic Burkitt lymphoma (eBL) is associated with Epstein-Barr virus (EBV) and Plasmodium falciparum malaria coinfections. However, the role of Kaposi sarcoma-associated herpesvirus (KSHV), also endemic in Africa, has not been evaluated as a cofactor in eBL pathogenesis., Methods: Multiplexed seroprofiles for EBV, malaria, and KSHV were generated for 266 eBL patients, 78 non-eBL cancers, and 202 healthy children. KSHV and EBV loads were quantified by PCR., Results: KSHV seroprevalence did not differ by study group but was associated with age. Seropositivity, defined by K8.1/LANA or in combination with 5 other KSHV antigens (ORF59, ORF65, ORF61, ORF38, and K5) was associated with antimalarial antibody levels to AMA1 (odds ratio [OR], 2.41, P < .001; OR, 2.07, P < .001) and MSP1 (OR, 2.41, P = .0006; OR, 5.78, P < .001), respectively. KSHV loads did not correlate with antibody levels nor differ across groups but were significantly lower in children with detectable EBV viremia (P = .014)., Conclusions: Although KSHV-EBV dual infection does not increase eBL risk, EBV appears to suppress reactivation of KSHV while malaria exposure is associated with KSHV infection and/or reactivation. Both EBV and malaria should, therefore, be considered as potential effect modifiers for KSHV-associated cancers in sub-Saharan Africa., (© The Author(s) 2020. Published by Oxford University Press for the Infectious Diseases Society of America. All rights reserved. For permissions, e-mail: journals.permissions@oup.com.)

Kaposi sarcoma (KS) is an angioproliferative disorder that is commonly associated with human herpes virus 8 as well as the HIV. In fact, KS is one of the most common AIDS-defining illnesses. KS typically presents with diffuse, violaceous cutaneous nodules, and may have concomitant visceral involvement. However, visceral involvement rarely occurs without skin manifestations. A rare case of localised bronchopulmonary KS without skin involvement is described in a patient with previously undiagnosed HIV. This atypical presentation represents a challenge for modern-day physicians in developed countries where the prevalence of AIDS-related diseases is decreasing., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2019. No commercial re-use. See rights and permissions. Published by BMJ.)

In this book chapter, we review the current knowledge of the biology and pathogenesis of Kaposi's sarcomaassociated herpesvirus (KSHV). We describe the lifecycle of KSHV, the cancers associated with this virus, as well as current treatment modalities.

We report a case of Endemic African Cutaneous Kaposi Sarcoma (EACKS) on the lower extremity of an immunocompetent 31-yr-old male service member from Cameroon. Diagnosis was made using clinical and histologic findings. The service member was treated with local radiation therapy with resolution of his tumor.The goal of this article is to educate practitioners to counsel susceptible service members and leadership on the risk of developing EACKS when traveling to Sub-Saharan Africa, monitor for disease development, and guide in the diagnosis and treatment of patients with this rare disease.

Oncogenic Kaposi's sarcoma-associated herpesvirus (KSHV) is etiologically linked to primary effusion lymphoma (PEL), an aggressive and nontreatable malignancy commonly found in AIDS patients. In this study, we performed a high-throughput screening of 3,731 characterized compounds and identified cytarabine, approved by the FDA for treating numerous types of cancer, as a potent inhibitor of KSHV-induced PEL. We showed the high efficacy of cytarabine in the growth inhibition of various PEL cells by inducing cell cycle arrest and apoptosis. Cytarabine inhibited host DNA and RNA syntheses and therefore induced cellular cytotoxicity. Furthermore, cytarabine inhibited viral DNA and RNA syntheses and induced the rapid degradation of KSHV major latent protein LANA (latency-associated nuclear antigen), leading to the suppression of KSHV latent replication. Importantly, cytarabine effectively inhibited active KSHV replication and virion production in PEL cells. Finally, cytarabine treatments not only effectively inhibited the initiation and progression of PEL tumors but also induced regression of grown PEL tumors in a xenograft mouse model. Altogether, our study has identified cytarabine as a novel therapeutic agent for treating PEL as well as eliminating KSHV persistent infection. IMPORTANCE Primary effusion lymphoma is an aggressive malignancy caused by Kaposi's sarcoma-associated herpesvirus. The outcome of primary effusion lymphoma is dismal without specific treatment. Through a high-throughput screening of characterized compounds, we identified an FDA-approved compound, cytarabine, as a potent inhibitor of primary effusion lymphoma. We showed that cytarabine induced regression of PEL tumors in a xenograft mouse model. Cytarabine inhibited host and viral DNA and RNA syntheses, resulting in the induction of cytotoxicity. Of interest, cytarabine induced the degradation of KSHV major latent protein LANA, hence suppressing KSHV latent replication, which is required for PEL cell survival. Furthermore, cytarabine inhibited KSHV lytic replication program, preventing virion production. Our findings identified cytarabine as a novel therapeutic agent for treating PEL as well as for eliminating KSHV persistent infection. Since cytarabine is already approved by the FDA, it might be an ideal candidate for repurposing for PEL therapy and for further evaluation in advanced clinical trials., (Copyright © 2018 Gruffaz et al.)

Signal transduction pathways play a key role in the regulation of cell growth, cell differentiation, cell survival, apoptosis, and immune responses. Bacterial and viral pathogens utilize the cell signal pathways by encoding their own proteins or noncoding RNAs to serve their survival and replication in infected cells. Kaposi's sarcoma-associated herpesvirus (KSHV), also known as human herpesvirus 8 (HHV-8), is classified as a rhadinovirus in the γ-herpesvirus subfamily and was the eighth human herpesvirus to be discovered from Kaposi's sarcoma specimens. KSHV is closely associated with an endothelial cell malignancy, Kaposi's sarcoma, and B-cell malignancies, primary effusion lymphoma, and multicentric Castleman's disease. Recent studies have revealed that KSHV manipulates the cellular signaling pathways to achieve persistent infection, viral replication, cell proliferation, anti-apoptosis, and evasion of immune surveillance in infected cells. This chapter summarizes recent developments in our understanding of the molecular mechanisms used by KSHV to interact with the cell signaling machinery.

Kaposi's sarcoma is a limphoangioproliferous tumor described for the first time in the year 1872 by Moritz Kaposi. There are four clinical variants, the classical form, the endemic, the iatrogenic associated to transplantation or immunosuppression and the epidemic associated with AIDS, which will be referred in this publication. In this research,(case, paperwork, investigation) a 31 year old male patient, who was diagnosed AIDS and Kaposi's sarcoma at the same time while in hospital, is described.

Primary effusion lymphoma (PEL) is a lymphogenic disorder associated with Kaposi's sarcoma-associated herpesvirus (KSHV) infection. Key to the survival and proliferation of PEL is the canonical NF-κB pathway, which becomes constitutively activated following overexpression of the viral oncoprotein KSHV vFLIP (ks-vFLIP). This arises from its capacity to form a complex with the modulatory subunit of the IκB kinase (IKK) kinase, IKKγ (or NEMO), resulting in the overproduction of proteins that promote cellular survival and prevent apoptosis, both of which are important drivers of tumorigenesis. Using a combination of cell-based and biophysical assays together with structural techniques, we showed that the observed resistance to cell death is largely independent of autophagy or major death receptor signaling pathways and demonstrated that direct targeting of the ks-vFLIP-IKKγ interaction both in cells and in vitro can be achieved using IKKγ-mimetic peptides. Our results further reveal that these peptides not only induce cell killing but also potently sensitize PEL to the proapoptotic agents tumor necrosis factor alpha and etoposide and are the first to confirm ks-vFLIP as a tractable target for the treatment of PEL and related disorders. IMPORTANCE KSHV vFLIP (ks-vFLIP) has been shown to have a crucial role in cellular transformation, in which it is vital for the survival and proliferation of primary effusion lymphoma (PEL), an aggressive malignancy associated with infection that is resistant to the majority of chemotherapeutic drugs. It operates via subversion of the canonical NF-κB pathway, which requires a physical interaction between ks-vFLIP and the IKK kinase modulatory subunit IKKγ. While this interaction has been directly linked to protection against apoptosis, it is unclear whether the suppression of other cell death pathways implicated in ks-vFLIP pathogenesis is an additional contributor. We demonstrate that the interaction between ks-vFLIP and IKKγ is pivotal in conferring resistance to apoptosis. Additionally, we show that the ks-vFLIP-IKKγ complex can be disrupted using peptides leading to direct killing and the sensitization of PEL cells to proapoptotic agents. Our studies thus provide a framework for future therapeutic interventions., (Copyright © 2017 Briggs et al.)

Kaposi's sarcoma (KS) is an endothelial tumor causally linked to Kaposi's sarcoma herpesvirus (KSHV) infection. At early stages of KS, inflammation and aberrant neoangiogenesis are predominant, while at late stages the disease is characterized by the proliferation of KSHV-infected spindle cells (SC). Since KSHV infection modifies the endothelial cell (EC) identity, the origin of SCs remains elusive. Yet, pieces of evidence indicate the lymphatic origin. KSHV-infected ECs display increased proliferative, angiogenic and migratory capacities which account for KS oncogenesis. Here we propose a model in which KSHV reprograms the EC identity, induces DNA damage and establishes a dysregulated gene expression program involving interplay of latent and lytic genes allowing continuous reinfection of ECs attracted to the tumor by the secretion of virus-induced cellular factors., (Copyright © 2017 Elsevier B.V. All rights reserved.)

Case: We report a case of kaposiform hemangioendothelioma (KHE) of the scapula in a 2-year-old boy with motor and sensory abnormalities of the left upper extremity, suggesting brachial plexus involvement. The locally invasive nature prevented resection; sirolimus therapy resulted in improvement of the motor and sensory impairment, as well as decreased tumor size on imaging., Conclusion: Osseous infiltration of KHE is known to occur, but its primary presentation in bone without skin involvement is rare and diagnostically challenging. Awareness of rare presentations of KHE, along with accurate histopathologic interpretation, is important to achieve a diagnosis and to differentiate KHE from more common vascular lesions (e.g., infantile hemangioma). Sirolimus therapy is emerging as a promising treatment for unresectable KHE.

Background: Throughout most of sub-Saharan Africa (and, indeed, most resource-limited areas), lack of death registries prohibits linkage of cancer diagnoses and precludes the most expeditious approach to determining cancer survival. Instead, estimation of cancer survival often uses clinical records, which have some mortality data but are replete with patients who are lost to follow-up (LTFU), some of which may be caused by undocumented death. The end result is that accurate estimation of cancer survival is rarely performed. A prominent example of a common cancer in Africa for which survival data are needed but for which frequent LTFU has precluded accurate estimation is Kaposi sarcoma (KS)., Methods: Using electronic records, we identified all newly diagnosed KS among HIV-infected adults at 33 primary care clinics in Kenya, Uganda, Nigeria, and Malawi from 2009 to 2012. We determined those patients who were apparently LTFU, defined as absent from clinic for ≥90 days at database closure and unknown to be dead or transferred. Using standardized protocols which included manual chart review, telephone calls, and physical tracking in the community, we attempted to update vital status amongst patients who were LTFU., Results: We identified 1222 patients with KS, of whom 440 were LTFU according to electronic records. Manual chart review revealed that 18 (4.1%) were classified as LFTU due to clerical error, leaving 422 as truly LTFU. Of these 422, we updated vital status in 78%; manual chart review was responsible for updating in 5.7%, telephone calls in 26%, and physical tracking in 46%. Among 378 patients who consented at clinic enrollment to be tracked if they became LTFU and who had sufficient geographic contact/locator information, we updated vital status in 88%. Duration of LTFU was not associated with success of tracking, but tracking success was better in Kenya than the other sites., Conclusion: It is feasible to update vital status in a large fraction of patients with HIV-associated KS in sub-Saharan Africa who have become LTFU from clinical care. This finding likely applies to other cancers as well. Updating vital status amongst lost patients paves the way towards accurate determination of cancer survival.

Kaposi's sarcoma-associated herpesvirus (KSHV) is the etiologic agent of Kaposi's sarcoma (KS), a vascular tumor frequently found in immunodeficient individuals. KSHV encodes 12 pre-microRNAs (pre-miRNAs), which are processed into 25 mature microRNAs (miRNAs). KSHV miRNAs maintain KSHV latency, enhance angiogenesis and dissemination of the infected cells, and interfere with the host immune system by regulating viral and cellular gene expression, ultimately contributing to KS development. In this review, we briefly introduce the biogenesis of miRNAs and then describe the recent advances in defining the roles and mechanisms of action of KSHV miRNAs in KS development., (Copyright © 2017 Elsevier Ltd. All rights reserved.)

The human oncogenic virus Kaposi's sarcoma-associated herpesvirus (KSHV) is linked to Kaposi's sarcoma (KS), a tumor of endothelial cells characterized by angiogenesis and invasiveness. KSHV genome encodes 25 mature microRNAs (miRNAs), but their roles in KSHV-induced tumor dissemination and angiogenesis are not fully understood. In this study, we constructed the sensor reporters of KSHV miRNAs and used a luciferase reporter assay to demonstrate the function of the mimics of KSHV miRNAs. Then, we examined the expression of matrix metalloproteinases (MMPs) and pro-angiogenic cytokines that are related to cell migration and angiogenesis in the KSHV 25 miRNAs transfected endothelial cells. We found that all KSHV miRNAs increased the expression of the transcripts of MMP1, MMP13, VEGFA, and VEGFR2 in different degrees, as well as the secretion of VEGFA protein in the supernatant of endothelial cells. Our results reveal that KSHV miRNAs contribute to regulating MMPs and expression of pro-angiogenic factors, thus, suggesting that these miRNAs might play a crucial role in KSHV-induced cell motility and angiogenesis., (© 2017 Wiley Periodicals, Inc.)

Kaposi's sarcoma (KS) is an unusual neoplasm characterized by extensive neoangiogenesis, infiltrates of inflammatory cells and atypically differentiated spindle cells of endothelial origin. KS is caused by an oncogenic γ-herpesvirus, Kaposi's sarcoma-associated herpesvirus (KSHV)/human herpesvirus-8 (HHV-8). Several KSHV proteins can subvert multiple cellular angiogenic, mitogenic and inflammatory pathways. Here, we discuss the KSHV encoded membrane proteins vGPCR, K1 and K15, with a particular emphasis on their activation of cellular signaling pathways and their role in the development of specific features of KS., (Copyright © 2016 Elsevier B.V. All rights reserved.)

We briefly report two cases of HIV/AIDS-associated Kaposi's sarcoma affecting the gastrointestinal tract. Both patients were seen at Edenvale General Hospital, Johannesburg, South Africa.

Herpesviruses can establish latent infections in the host with severely limited viral gene expression. Kaposi's Sarcoma-associated herpesvirus (KSHV) is found predominantly in the latent state in the main KS tumor cell, a cell of endothelial origin. While many viruses alter host cell metabolism during productive infection, latent KSHV infection of endothelial cells activates metabolic pathways that are activated in many cancer cells. Inhibition of these major metabolic pathways leads to apoptotic cell death of the latently infected cells. The study of KSHV activation of metabolism may lead to novel therapeutic options for eliminating latent infection of gamma-herpesviruses and could also lead to a deeper mechanistic understanding of how to target cancer cell metabolism., (Copyright © 2016 Elsevier B.V. All rights reserved.)

A woman in her 30s presented with recurrent low-grade fever and cough (onset, 1 week). She reported occasional night sweats and weight loss of approximately 20 pounds over the past 4 months. She denied nausea, vomiting, diarrhea, or any urinary complaints. Her past medical history was significant for chronic hepatitis C and HIV infection, the latter diagnosed in 2001. She was noncompliant with highly active antiretroviral therapy for more than 4 years and had pneumocystis pneumonia 2 years prior to this presentation. She had a 10-pack per year smoking history and reported active use of cocaine and heroin. The patient denied any occupational exposures., (Copyright © 2016 American College of Chest Physicians. Published by Elsevier Inc. All rights reserved.)

Background: Kaposi's sarcoma (KS)-associated herpesvirus (KSHV) is the etiologic agent of KS, the most common AIDS-related malignancy. The majority of KS tumor cells harbor latent KSHV virus but only a small percentage undergoes spontaneous lytic replication. Viral reactivation from latency is crucial for the pathogenesis and development of KS, but the cellular mechanisms underlying the switch between viral latency and replication are not well understood., Methods: The level of let-7 miRNAs and MAP4K4 in KSHV infected 293T cells were quantified by real-time PCRs. Let-7 expression was silenced by the miRNA sponge technique. In let-7a transfected 293T cells, the expression of MAP4K4 was measured by real-time PCR and western blot. Luciferease expression was employed to examine the effect of let-7a on the 3'-untranslated region (UTR) of the MAP4K4 gene in 293T cells. Real-time PCR was used to quantify the KSHV copy numbers in BC-3 cells in which the expression of let-7a and/or MAP4K4 were altered. Finally, ERK, JNK and p38 protein production and their phosphorylation status were detected by western blots in let-7a or MAP4K4 transfected BCBL-1 cells., Results: The expression of microRNA let-7 was dramatically decreased in KSHV infected 293T cells, but that of MAP4K4 was increased significantly. Let-7a is physically associated with and targets the MAP4K4 3'UTR, and inhibits MAP4K4 expression at both mRNA and protein levels. MAP4K4 stimulates KSHV reactivation from latency, whereas let-7a inhibits the function of MAP4K4 by reversing the function of MAP4K4 on JNK, phospho-JNK and phospho-ERK1/2 levels., Conclusion: Our results establish that let-7a specifically suppresses MAP4K4 expression, and further inhibits KSHV reactivation by interfering with the function of MAP4K4 on the MAPK pathway, highlighting let-7a as a potential treatment for KS.

Objectives: The aim of the study was to identify factors associated with the time between opportunistic disease (OD) diagnosis and antiretroviral therapy (ART) initiation in HIV-infected patients presenting for care with an OD, and to evaluate the outcomes associated with any delay., Methods: A multicentre cohort study was undertaken in London, Paris and Lille/Tourcoing. The medical records of patients diagnosed from 2002 to 2012 were reviewed., Results: A total of 437 patients were enrolled in the study: 70% were male, the median age was 40 years, 42% were from sub-Saharan Africa, 68% were heterosexual, the median CD4 count was 40 cells/μL, and the most common ODs were Pneumocystis pneumonia (37%), tuberculosis (24%), toxoplasmosis (12%) and Kaposi's sarcoma (11%). Of these patients, 400 (92%) started ART within 24 weeks after HIV diagnosis, with a median time from OD diagnosis to ART initiation of 30 [interquartile range (IQR) 16-58] days. Patients diagnosed between 2009 and 2012 had a shorter time to ART initiation than those diagnosed in earlier years [hazard ratio (HR) 2.07; 95% confidence interval (CI) 1.58-2.72]. Factors associated with a longer time to ART initiation were a CD4 count ≥ 200 cells/μL (HR 0.30; 95% CI 0.20-0.44), tuberculosis (HR 0.40; 95% CI 0.30-0.55) and diagnosis in London (HR 0.62; 95% CI 0.48-0.80). Patients initiating 'deferred' ART (by ≥ 30 days) exhibited no difference in disease progression or immunovirological response compared with patients who had shorter times to ART initiation. Patients in the 'deferred' group were less likely to have ART modifications (HR 0.69; 95% CI 0.48-1.00) and had shorter in-patient stays (mean 14.2 days shorter; 95% CI 8.9-19.5 days) than patients in the group whose ART was not deferred., Conclusions: The time between OD diagnosis and ART initiation remains heterogeneous and relatively long, particularly in individuals with a high CD4 count or tuberculosis or those diagnosed in London. Deferring ART was associated with fewer ART modifications and shorter in-patient stays., (© 2014 British HIV Association.)

Since the development of combination antiretroviral therapy (cART), the incidence and mortality associated with Kaposi sarcoma (KS) have been reduced, although not eliminated. Clinical presentations of KS range from simple skin involvement to disseminated disease, including involvement of the oral cavity and viscera, which portends a more ominous prognosis. Multiple case reports and data from clinical trials indicate that administration of systemic corticosteroids may aggravate KS. We present a case of disseminated KS following administration of prednisone for presumed immune reconstitution inflammatory syndrome (IRIS) associated with fungal pneumonia in an HIV-infected individual. The discussion that follows outlines the pathophysiology and clinical presentations associated with KS and existing data for the role of corticosteroids in promoting KS progression.

Kaposi's sarcoma-associated herpesvirus (KSHV) latently infects tumor cells and persists as a multiple-copy, extrachromosomal, circular episome. To persist, the viral genome must replicate with each cell cycle. The KSHV latency-associated nuclear antigen (LANA) mediates viral DNA replication and persistence, but little is known regarding the underlying mechanisms. We find that LANA recruits replication factor C (RFC), the DNA polymerase clamp [proliferating cell nuclear antigen (PCNA)] loader, to drive DNA replication efficiently. Mutated LANA lacking RFC interaction was deficient for LANA-mediated DNA replication and episome persistence. RFC depletion had a negative impact on LANA's ability to replicate and maintain viral DNA in cells containing artificial KSHV episomes or in infected cells, leading to loss of virus. LANA substantially increased PCNA loading onto DNA in vitro and recruited RFC and PCNA to KSHV DNA in cells. These findings suggest that PCNA loading is a rate-limiting step in DNA replication that is incompatible with viral survival. LANA enhancement of PCNA loading permits efficient virus replication and persistence, revealing a previously unidentified mechanism for KSHV latency.

Unlabelled: Hypoxia-inducible factor 1α (HIF-1α) has been frequently implicated in many cancers as well as viral pathogenesis. Kaposi's sarcoma-associated herpesvirus (KSHV) is linked to several human malignancies. It can stabilize HIF-1α during latent infection and undergoes lytic replication in response to hypoxic stress. However, the mechanism by which KSHV controls its latent and lytic life cycle through the deregulation of HIF-1α is not fully understood. Our previous studies showed that the hypoxia-sensitive chromatin remodeler KAP1 was targeted by the KSHV-encoded latency-associated nuclear antigen (LANA) to repress expression of the major lytic replication and transcriptional activator (RTA). Here we further report that an RNA interference-based knockdown of KAP1 in KSHV-infected primary effusion lymphoma (PEL) cells disrupted viral episome stability and abrogated sub-G1/G1 arrest of the cell cycle while increasing the efficiency of KSHV lytic reactivation by hypoxia or using the chemical 12-O-tetradecanoylphorbol-13-acetate (TPA) or sodium butyrate (NaB). Moreover, KSHV genome-wide screening revealed that four hypoxia-responsive clusters have a high concurrence of both RBP-Jκ and HIF-1α binding sites (RBS+HRE) within the same gene promoter and are tightly associated with KAP1. Inhibition of KAP1 greatly enhanced the association of RBP-Jκ with the HIF-1α complex for driving RTA expression not only in normoxia but also in hypoxia. These results suggest that both KAP1 and the concurrence of RBS+HRE within the RTA promoter are essential for KSHV latency and hypoxia-induced lytic reactivation., Importance: Kaposi's sarcoma-associated herpesvirus (KSHV), a DNA tumor virus, is an etiological agent linked to several human malignancies, including Kaposi's sarcoma (KS) and primary effusion lymphoma (PEL). HIF-1α, a key hypoxia-inducible factor, is frequently elevated in KSHV latently infected tumor cells and contributes to KSHV lytic replication in hypoxia. The molecular mechanisms of how KSHV controls the latent and lytic life cycle through deregulating HIF-1α remain unclear. In this study, we found that inhibition of hypoxia-sensitive chromatin remodeler KAP1 in KSHV-infected PEL cells leads to a loss of viral genome and increases its sensitivity to hypoxic stress, leading to KSHV lytic reactivation. Importantly, we also found that four hypoxia-responsive clusters within the KSHV genome contain a high concurrence of RBP-Jκ (a key cellular regulator involved in Notch signaling) and HIF-1α binding sites. These sites are also tightly associated with KAP1. This discovery implies that KAP1, RBP-Jκ, and HIF-1α play an essential role in KSHV pathogenesis through subtle cross talk which is dependent on the oxygen levels in the infected cells., (Copyright © 2014, American Society for Microbiology. All Rights Reserved.)

Background: Skin cancer is the most common malignancy to arise after organ transplantation in Caucasians, but limited data are available on its incidence in Asian transplant recipients., Objective: We sought to assess the incidence of skin cancer after organ transplantation in a Korean cohort., Methods: A cohort study was conducted to determine the incidence and risk factors for skin cancers among kidney, liver, heart, or pancreas transplant recipients, treated at the Asan Medical Center in Seoul, Korea., Results: The cumulative incidences of skin cancer were 0.70% at 5 years, 1.66% at 10 years, and 2.31% at 15 years. For all skin cancers, squamous cell carcinoma, basal cell carcinoma, and Kaposi sarcoma, the standardized incidence ratios between the recipients and the Korean general population were 30.9 (95% confidence interval, 12.4-63.6), 61.9 (12.8-180.8), 11.9 (0.3-66.1), and 565.2 (68.4-2041.6) after the end of the fifth posttransplantation year, respectively., Limitations: We cannot exclude the possibility of both the underestimation because of potential missing cases and the overestimation because of the ascertainment bias., Conclusion: The incidence of posttransplantation skin cancer is very low in Korean patients. However, the risk of skin cancer in organ transplant recipients may be considerably higher than that in the Korean general population., (Copyright © 2013 American Academy of Dermatology, Inc. Published by Mosby, Inc. All rights reserved.)

Lack of an effective small-animal model to study the Kaposi's sarcoma-associated herpesvirus (KSHV) infection in vivo has hampered studies on the pathogenesis and transmission of KSHV. The objective of our study was to determine whether the humanized BLT (bone marrow, liver, and thymus) mouse (hu-BLT) model generated from NOD/SCID/IL2rγ mice can be a useful model for studying KSHV infection. We have tested KSHV infection of hu-BLT mice via various routes of infection, including oral and intravaginal routes, to mimic natural routes of transmission, with recombinant KSHV over a 1- or 3-mo period. Infection was determined by measuring viral DNA, latent and lytic viral transcripts and antigens in various tissues by PCR, in situ hybridization, and immunohistochemical staining. KSHV DNA, as well as both latent and lytic viral transcripts and proteins, were detected in various tissues, via various routes of infection. Using double-labeled immune-fluorescence confocal microscopy, we found that KSHV can establish infection in human B cells and macrophages. Our results demonstrate that KSHV can establish a robust infection in the hu-BLT mice, via different routes of infection, including the oral mucosa which is the most common natural route of infection. This hu-BLT mouse not only will be a useful model for studying the pathogenesis of KSHV in vivo but can potentially be used to study the routes and spread of viral infection in the infected host.

Diffuse multi-spectral imaging has been evaluated as a potential non-invasive marker of tumor response. Multi-spectral images of Kaposi sarcoma skin lesions were taken over the course of treatment, and blood volume and oxygenation concentration maps were obtained through principal component analysis (PCA) of the data. These images were compared with clinical and pathological responses determined by conventional means. We demonstrate that cutaneous lesions have increased blood volume concentration and that changes in this parameter are a reliable indicator of treatment efficacy, differentiating responders and non-responders. Blood volume decreased by at least 20% in all lesions that responded by clinical criteria and increased in the two lesions that did not respond clinically. Responses as assessed by multi-spectral imaging also generally correlated with overall patient clinical response assessment, were often detectable earlier in the course of therapy, and are less subject to observer variability than conventional clinical assessment. Tissue oxygenation was more variable, with lesions often showing decreased oxygenation in the center surrounded by a zone of increased oxygenation. This technique could potentially be a clinically useful supplement to existing response assessment in KS, providing an early, quantitative, and non-invasive marker of treatment effect.

In this observational cohort study, 10 patients with extensive or treatment-refractory AIDS-associated Kaposi sarcoma were treated with peginterferon alfa-2a. Tumor responses were observed in 9 patients with a median progression-free survival of 645 days. Peginterferon alfa-2a could be an effective therapy for extensive or treatment-resistant Kaposi sarcoma.

MicroRNAs (miRNAs) are stable, small non-coding RNAs that modulate many downstream target genes. Recently, circulating miRNAs have been detected in various body fluids and within exosomes, prompting their evaluation as candidate biomarkers of diseases, especially cancer. Kaposi's sarcoma (KS) is the most common AIDS-associated cancer and remains prevalent despite Highly Active Anti-Retroviral Therapy (HAART). KS is caused by KS-associated herpesvirus (KSHV), a gamma herpesvirus also associated with Primary Effusion Lymphoma (PEL). We sought to determine the host and viral circulating miRNAs in plasma, pleural fluid or serum from patients with the KSHV-associated malignancies KS and PEL and from two mouse models of KS. Both KSHV-encoded miRNAs and host miRNAs, including members of the miR-17-92 cluster, were detectable within patient exosomes and circulating miRNA profiles from KSHV mouse models. Further characterization revealed a subset of miRNAs that seemed to be preferentially incorporated into exosomes. Gene ontology analysis of signature exosomal miRNA targets revealed several signaling pathways that are known to be important in KSHV pathogenesis. Functional analysis of endothelial cells exposed to patient-derived exosomes demonstrated enhanced cell migration and IL-6 secretion. This suggests that exosomes derived from KSHV-associated malignancies are functional and contain a distinct subset of miRNAs. These could represent candidate biomarkers of disease and may contribute to the paracrine phenotypes that are a characteristic of KS.

The predominant tumor cell of Kaposi's Sarcoma (KS) is the spindle cell, a cell of endothelial origin that expresses markers of lymphatic endothelium. In culture, Kaposi's Sarcoma-associated herpesvirus (KSHV) infection of blood endothelial cells drives expression of lymphatic endothelial cell specific markers, in a process that requires activation of the gp130 receptor and the JAK2/STAT3 and PI3K/AKT signaling pathways. While expression of each of the KSHV major latent genes in endothelial cells failed to increase expression of lymphatic markers, the viral homolog of human IL-6 (vIL-6) was sufficient for induction and requires the JAK2/STAT3 and PI3K/AKT pathways. Therefore, activation of gp130 and downstream signaling by vIL-6 is sufficient to drive blood to lymphatic endothelial cell differentiation. While sufficient, vIL-6 is not necessary for lymphatic reprogramming in the context of viral infection. This indicates that multiple viral genes are involved and suggests a central importance of this pathway to KSHV pathogenesis., (Copyright © 2012 Elsevier Inc. All rights reserved.)

Kaposi sarcoma (KS), an angioproliferative disease associated with Kaposi sarcoma herpesvirus (KSHV) infection, harbors a diversity of cell types ranging from endothelial to mesenchymal cells of unclear origin. We developed a three-dimensional cell model for KSHV infection and used it to demonstrate that KSHV induces transcriptional reprogramming of lymphatic endothelial cells to mesenchymal cells via endothelial-to-mesenchymal transition (EndMT). KSHV-induced EndMT was initiated by the viral proteins vFLIP and vGPCR through Notch pathway activation, leading to gain of membrane-type-1 matrix metalloproteinase (MT1-MMP)-dependent invasive properties and concomitant changes in viral gene expression. Mesenchymal markers and MT1-MMP were found codistributed with a KSHV marker in the same cells from primary KS biopsies. Our data explain the heterogeneity of cell types within KS lesions and suggest that KSHV-induced EndMT may contribute to KS development by giving rise to infected, invasive cells while providing the virus a permissive cellular microenvironment for efficient spread., (Copyright © 2011 Elsevier Inc. All rights reserved.)

Kaposi's sarcoma (KS), a low-grade malignancy that is associated with human herpesvirus-8 (HHV-8), is a multifocal tumor that most commonly affects mucocutaneous sites. It might also involve lymph nodes and visceral organs, in particular of the respiratory and gastrointestinal tract, but it can affect every organ system. Four forms of the disease have been recognized: the classic, the endemic, the transplant-associated, and the epidemic form. The endemic form, or African KS, currently accounts for 10%-50% of all cancers in adults and up to 25% of cancers in children in certain parts of Africa. The epidemic form or acquired immune deficiency syndrome (AIDS)-associated KS is a frequent neoplasm in bisexual and homosexual men with AIDS in the United States. Even though in North America and Europe the incidence of KS in men with AIDS has decreased significantly after the introduction of highly active antiretroviral therapy (HAART), in some developing countries, the incidence of KS keeps growing. The pathophysiology, clinical manifestations, imaging findings, and more relevant differential diagnoses are reviewed., (Copyright © 2011 Elsevier Inc. All rights reserved.)

The analysis of 40 histories of disease of the patients with histologically confirmed diagnosis of classical KS for the period from 1991 to 2006 has shown, that under conditions of our region the clinical picture of classical KS undergoes changes. The first signs of disease are registered at 35% of the patients at the age under 50 years, among the first manifestations of disease in 20% of cases the swellings meet, 17,5% have variants with atypical localization on the face, head, neck, there are cases of transition of chronic process into subacute with absence of correlation between prevalence of process and acuteness of its development. The average age of the patients to the beginning of disease was 49,6 years.

Importance of the Field: Kaposi sarcoma (KS) occurs as a result of Kaposi sarcoma-associated herpesvirus (KSHV) infection, typically in the context of an immunodeficient state such as coinfection with HIV or transplantation. Systemic treatment of KS has traditionally involved one of several chemotherapeutic agents either in combination or as single agents, which typically provides reasonable response rates and short-term control. However, recurrence of KS is common and progression-free intervals are short. For these reasons, new therapies are being sought., Areas Covered in This Review: This review describes the contemporary pathobiology of KS targets, current limitations of standard treatment options, and examines the findings of completed and ongoing clinical trials of novel, molecularly targeted treatments for patients with KS., What the Reader Will Gain: The reader will be presented with key clinicopathological characteristics and the pathogenesis of KS. Standard therapy for KS is reviewed including local, regional and systemic treatments. Molecular targets related to LANA-mediated and vGPCR-mediated signaling, angiogenesis, apoptosis and KSHV replication are discussed in detail. The reader will be provided with a compilation of agents, their mechanism of action, and results on various molecularly target agents in KS., Take Home Message: With the elucidation of novel pathogenic mechanisms of KS including KSHV replication, restoration of immune competence and signal transduction pathways utilized by KSHV in the propagation of KS, rational therapeutic targets have been identified.

Kaposi's sarcoma-associated herpesvirus (KSHV) is linked with Kaposi's sarcoma and lymphomas. The pathogenesis of KSHV depends on the balance between two phases of the viral cycle: latency and lytic replication. In this study, we report that KSHV-encoded microRNAs (miRNAs) function as regulators by maintaining viral latency and inhibiting viral lytic replication. MiRNAs are short, noncoding, small RNAs that post-transcriptionally regulate the expression of messenger RNAs. Of the 12 viral miRNAs expressed in latent KSHV-infected cells, we observed that expression of miR-K3 can suppress both viral lytic replication and gene expression. Further experiments indicate that miR-K3 can regulate viral latency by targeting nuclear factor I/B. Nuclear factor I/B can activate the promoter of the viral immediate-early transactivator replication and transcription activator (RTA), and depletion of nuclear factor I/B by short hairpin RNAs had similar effects on the viral life cycle to those of miR-K3. Our results suggest a role for KSHV miRNAs in regulating the viral life cycle.

A 3-year-old girl presented with a hemorrhagic conjunctival lesion in the right eye. The medical history revealed premature cessation of breast feeding, intolerance to the ingestion of baby foods, anorexia, and abdominal distention. Prior to her referral, endoscopic small intestinal biopsy had been carried out under general anesthesia with a possible diagnosis of Celiac Disease (CD). Her parents did not want their child to undergo general anesthesia for the second time for the excisional biopsy. We decided to follow the patient until all systemic investigations were concluded. In evaluation, the case was diagnosed with CD and the conjunctival tumor showed complete regression during gluten-free dietary treatment. The clinical fleshy appearance of the lesion with spider-like vascular extensions and subconjunctival hemorrhagic spots, possible association with an acquired immune system dysfunction due to CD, and spontaneous regression by a gluten-free diet led us to make a presumed diagnosis of conjunctival Kaposi sarcoma.

Kaposi's sarcoma (KS) is an enigmatic vascular tumor thought to be a consequence of dysregulated expression of the human herpesvirus-8 (HHV-8 or KSHV)-encoded G protein-coupled receptor (vGPCR). Indeed, transgenic animals expressing vGPCR manifest vascular tumors histologically identical to human KS, with expression of the viral receptor limited to a few cells, suggestive of a paracrine mechanism for vGPCR tumorigenesis. Both human and vGPCR experimental KS lesions are characterized by prominent angiogenesis and vascular permeability attributed to the release of angiogenic molecules, most notably vascular endothelial growth factor. However, the relative contribution of these paracrine mediators to the angiogenic and exudative phenotype of KS lesions remains unclear. Here we show that vGPCR up-regulation of Angiopoietin-like 4 (ANGPTL4) plays a prominent role in promoting the angiogenesis and vessel permeability observed in KS. Indeed, ANGPTL4 expression is a hallmark of vGPCR experimental and human KS lesions. Inhibition of ANGPTL4 effectively blocks vGPCR promotion of the angiogenic switch and vascular leakage in vitro and tumorigenesis in vivo. These observations suggest that ANGPTL4 is a previously unrecognized target for the treatment of patients with KS. As angiogenesis and increased vessel permeability are common themes in all solid tumors, these findings may have a broad impact on our understanding and treatment of cancer.

Kaposi sarcoma herpesvirus (KSHV) induces transcriptional reprogramming of endothelial cells. In particular, KSHV-infected lymphatic endothelial cells (LECs) show an up-regulation of genes associated with blood vessel endothelial cells (BECs). Consequently, KSHV-infected tumor cells in Kaposi sarcoma are poorly differentiated endothelial cells, expressing markers of both LECs and BECs. MicroRNAs (miRNAs) are short noncoding RNA molecules that act post-transcriptionally to negatively regulate gene expression. Here we validate expression of the KSHV-encoded miRNAs in Kaposi sarcoma lesions and demonstrate that these miRNAs contribute to viral-induced reprogramming by silencing the cellular transcription factor MAF (musculoaponeurotic fibrosarcoma oncogene homolog). MAF is expressed in LECs but not in BECs. We identify a novel role for MAF as a transcriptional repressor, preventing expression of BEC-specific genes, thereby maintaining the differentiation status of LECs. These findings demonstrate that viral miRNAs could influence the differentiation status of infected cells, and thereby contribute to KSHV-induced oncogenesis.

Objective: We aim to report a case of Kaposi sarcoma (KS) with Cushing's syndrome caused by endogenic glucocorticoid-induced immunosuppression., Clinical Presentation: A 43-year-old woman presented with delirium, hirsutism, fatigue, and hypertension. At the time of presentation, physical findings showed a Cushingoid appearance, with moon-like facies, hirsutism, and hyperpigmentation. Laboratory findings showed the following: adrenocorticotropic hormone, 86.7 pg/mL (normal range, 0-46 pg/mL); baseline cortisol level, 50 microg/dL (normal range, 6.2-19 microg/dL); potassium, 2.2 mEq/L (normal range, 3.5-5 mEq/L); and midnight cortisol level, 33 microg/dL. Serum cortisol levels failed to suppress after low and high doses of dexamethasone; these findings confirmed the diagnosis of ectopic adrenocorticotropic hormone production. Magnetic resonance imaging revealed a 12 x 15-mm, round, hypothalamic mass lesion in the center of the median eminence., Intervention: Endoscopic biopsy from the floor of the third ventricle was performed, and pathological examination of the lesion showed a diffuse adrenocorticotropic hormone-secreting adenoma. The patient developed diffuse skin lesions that were proven to be a KS by skin biopsy while she was prepared for transcranial surgery. After surgical removal of the adenoma, she became hypocortisolemic and required cortisol replacement. Within 1 month after surgery, all KS lesions disappeared spontaneously., Conclusion: Excessive cortisol may induce immunosuppression. KS is one of the most common malignant tumors of patients with immunosuppression. To the best of our knowledge, this is the first case of Cushing's syndrome with KS caused by endogenous glucocorticoid-induced immunosuppression.

Study Design: Resident's case problem., Background: Kaposi's sarcoma (KS) is the most common form of cancer in patients with human immunodeficiency virus (HIV) infection. Although KS is often initially asymptomatic, this neoplasm may progress to affect multiple organ systems, including structures of the musculoskeletal system, which can produce symptoms similar to those associated with common orthopaedic conditions. This resident's case problem describes the evaluation and differential diagnosis of a 45-year-old male with HIV and KS, referred to physical therapy with an initial diagnosis of radiographic osteoarthritis (OA) and patellofemoral pain syndrome (PFPS) of the left knee. His primary complaint was knee pain during end range knee flexion., Diagnosis: The history, systems review, and examination suggested a source of pain of a nonorthopaedic origin. Differential examination ruled out clinical OA, PFPS, ligament/cartilage derangement, and tendonitis. Avascular necrosis of the medial femoral condyle was also considered as a possible source of pain. Recent blood tests indicated a high viral load and low CD4 count, which might have increased susceptibility to opportunistic infections or KS tumor progression. The patient was referred back to his physician for additional follow-up. Magnetic resonance imaging (MRI) of the knees were consistent with a systemic inflammatory process such as KS. A true-cut biopsy was subsequently scheduled, which confirmed KS lesions at the left knee., Discussion: Physical therapists who manage orthopaedic conditions should be aware of the disablement that may result from acquired immunodeficiency syndrome-related KS. A thorough joint-specific examination, with a broad differential diagnosis, should be employed for patients having known systemic diseases., Level of Evidence: Differential diagnosis, level 4.

Survivin is a master regulator of cell proliferation and cell viability and is highly expressed in most human tumors. The molecular network linked to survivin expression in tumors has not been completely elucidated. In this study, we show that latency-associated nuclear antigen (LANA), a multifunctional protein of Kaposi's sarcoma-associated herpesvirus (KSHV) that is found in Kaposi's sarcoma tumors, upregulates survivin expression and increases the proliferation of KSHV-infected B cells. Analysis of pathway-specific gene arrays showed that survivin expression was highly upregulated in BJAB cells expressing LANA. The mRNA levels of survivin were also upregulated in HEK 293 and BJAB cells expressing LANA. Similarly, protein levels of survivin were significantly higher in LANA-expressing, as well as KSHV-infected, cells. Survivin promoter activity assays identified GC/Sp1 and p53 cis-acting elements within the core promoter region as being important for LANA activity. Gel mobility shift assays revealed that LANA forms a complex with Sp1 or Sp1-like proteins bound to the GC/Sp1 box of the survivin promoter. In addition, a LANA/p53 complex bound to the p53 cis-acting element within the survivin promoter, indicating that upregulation of survivin expression can also occur through suppression of p53 function. Furthermore, immunohistochemistry analyses revealed that survivin expression was upregulated in KSHV-associated Kaposi's sarcoma tissue, suggesting that LANA plays an important role in the upregulation of survivin expression in KSHV-infected endothelial cells. Knockdown of survivin expression by lentivirus-delivered small hairpin RNA resulted in loss of cell proliferation in KSHV-infected cells. Therefore, upregulation of survivin expression in KSHV-associated human cells contributes to their proliferation.