Inhibition of constitutive signaling of Kaposi's sarcoma-associated herpesvirus G protein-coupled receptor by protein kinases in mammalian cells in culture.

Kaposi's sarcoma-associated herpesvirus (KSHV)/human herpesvirus 8, which is consistently present in tissues of patients with Kaposi's sarcoma and primary effusion lymphomas, contains a gene that encodes a G protein-coupled receptor (KSHV-GPCR). We recently showed that KSHV-GPCR exhibits constitutive signaling via activation of phosphoinositide-specific phospholipase C and stimulates cell proliferation and transformation. In this study, we determined whether normal cellular mechanisms could inhibit constitutive signaling by KSHV-GPCR and thereby KSHV-GPCR-stimulated proliferation. We show that coexpression of GPCR-specific kinases (GRKs) and activation of protein kinase C inhibit constitutive signaling by KSHV-GPCR in COS-1 monkey kidney cells and in mouse NIH 3T3 cells. Moreover, GRK-5 but not GRK-2 inhibits KSHV-GPCR-stimulated proliferation of rodent fibroblasts. These data provide evidence that cell regulatory pathways of receptor desensitization may be therapeutic targets in human diseases involving constitutively active receptors.

Human herpesvirus-8/Kaposi's sarcoma-associated herpesvirus is a new transmissible virus that infects B cells.

Herpesviral DNA fragments isolated from AIDS-associated Kaposi's sarcoma (KS) tissue (KSHV-DNA) share homology with two lymphotropic oncogenic gamma-herpesviruses, Epstein-Barr virus and Herpesvirus saimiri, and are present in the lesions of more than 95% of HIV and non-HIV-associated forms of KS, AIDS-related body cavity-based lymphomas, and AIDS-related multicentric Castleman's disease. Here we show that BC-1, a KSHV-DNA-positive, body cavity-based lymphoma cell line, produces infective herpesviral particles carrying a linear 270-kb genome that specifically transmits KSHV-DNA to CD19+ B cells. Transmission of KSHV-DNA is dependent upon a biologically active, replicating virus, since it is blocked by UV irradiation and foscarnet, an inhibitor of viral DNA-polymerase. This study represents the first isolation and transmission of the human herpesvirus-8/KS-associated herpesvirus.

Mutations in the first exon are associated with altered transcription of c-myc in Burkitt lymphoma.

The c-myc proto-oncogene is involved in chromosomal translocations that are specifically and consistently found in Burkitt lymphoma. Although these translocations are thought to lead to a deregulation of c-myc expression, the structural and functional basis of this phenomenon has not been identified. Mutations in a specific region spanning approximately 70 base pairs and located at the 3' border of the first exon of translocated c-myc alleles were consistently detected in Burkitt lymphoma cells carrying classic (8:14) as well as variant (8:22 and 2:8) translocations. These structural alterations were accompanied by an altered pattern of c-myc transcription, namely, the removal of a block to transcriptional elongation that has been mapped to the same region. Thus, specific c-myc mutations leading to the alleviation of this block to transcriptional elongation may represent a general mechanism causing c-myc activation in Burkitt lymphoma.

Identification of herpesvirus-like DNA sequences in AIDS-associated Kaposi's sarcoma.

Representational difference analysis was used to isolate unique sequences present in more than 90 percent of Kaposi's sarcoma (KS) tissues obtained from patients with acquired immunodeficiency syndrome (AIDS). These sequences were not present in tissue DNA from non-AIDS patients, but were present in 15 percent of non-KS tissue DNA samples from AIDS patients. The sequences are homologous to, but distinct from, capsid and tegument protein genes of the Gammaherpesvirinae, herpesvirus saimiri and Epstein-Barr virus. These KS-associated herpesvirus-like (KSHV) sequences appear to define a new human herpesvirus.

Deregulation of c-Myc in primary effusion lymphoma by Kaposi's sarcoma herpesvirus latency-associated nuclear antigen.

Primary effusion lymphoma (PEL) is a rare subtype of non-Hodgkin's lymphoma, which is associated with infection by Kaposi's sarcoma herpesvirus (KSHV)/human herpesvirus-8. The c-Myc transcription factor plays an important role in cellular proliferation, differentiation and apoptosis. Lymphomas frequently have deregulated c-Myc expression owing to chromosomal translocations, amplifications or abnormal stabilization. However, no structural abnormalities were found in the c-myc oncogene in PEL. Given that c-Myc is often involved in lymphomagenesis, we hypothesized that it is deregulated in PEL. We report that PEL cells have abnormally stable c-Myc protein. The turnover of c-Myc protein is stringently regulated by post-transcriptional modifications, including phosphorylation of c-Myc threonine 58 (T58) by glycogen synthase kinase-3beta (GSK-3beta). Our data show that the impaired c-Myc degradation in PEL cells is associated with a significant underphosphorylation of c-Myc T58. The KSHV latency-associated nuclear antigen (LANA) is responsible for this deregulation. Overexpression of LANA in human embryonic kidney 293 or peripheral blood B cells leads to post-transcriptional deregulation of c-Myc protein. Conversely, when LANA is eliminated from PEL cells using RNA interference, GSK-3beta-mediated c-Myc T58 phosphorylation is restored. The presence of c-Myc and LANA in GSK-3beta-containing complexes in PEL cells further confirms the significance of these interactions in naturally KSHV-infected cells.

Immunophenotypic analysis of the Kaposi sarcoma herpesvirus (KSHV; HHV-8)-infected B cells in HIV+ multicentric Castleman disease (MCD).

AIMS: Kaposi sarcoma herpesvirus (KSHV) is aetiologically related to Kaposi sarcoma, classical and extracavitary primary effusion lymphoma (PEL; EC-PEL) and multicentric Castleman disease (MCD), entities preferentially occurring in HIV-infected individuals. Characterization of HIV-associated PELs/EC-PELs suggests that the KSHV-infected malignant cells originate from a pre-terminal stage of B-cell differentiation. However, only limited phenotypic studies have been performed on HIV+ MCD, including for PR domain containing 1 with zinc finger domain/B lymphocyte-induced maturation protein 1 (PRDM1/BLIMP1), a key regulator of terminal B-cell differentiation. The aim was to characterize KSHV-infected cells in 17 cases of HIV+ MCD. METHODS AND RESULTS: Double immunohistochemistry and immunohistochemistry-in situ hybridization were used to characterize the KSHV-infected cells in MCD; the results were compared with the phenotypic profiles of 39 PELs/EC-PELs and seven PEL cell lines. Whereas the immunophenotype of KSHV-infected cells in MCD and malignant KSHV+ PEL cells was similar (PAX5, Bcl-6-; PRDM1/BLIMP1, IRF4/MUM1+; Ki67+), the MCD KSHV-infected cells differed, as they expressed OCT2, cytoplasmic lambda immunoglobulin; variably expressed CD27; lacked CD138; and were Epstein-Barr virus negative. CONCLUSIONS: Although both PEL and MCD originate from KSHV-infected pre-terminally differentiated B cells, these findings, with previously reported genetic studies, indicate HIV+ MCD may arise from extrafollicular B cells, whereas PELs may originate from cells that have traversed the germinal centre.

Kaposi sarcoma-associated herpesvirus and other viruses in human lymphomagenesis.

Kaposi sarcoma-associated herpesvirus (KSHV), also called human herpesvirus 8 (HHV-8), is associated with a specific subset of lymphoproliferative disorders. These include two main categories. The first is primary effusion lymphomas and related solid variants. The second is multicentric Castleman disease, from which KSHV-positive plasmablastic lymphomas can arise. KSHV contributes to lymphomagenesis by subverting the host cell molecular signaling machinery to deregulate cell growth and survival. KSHV expresses a selected set of genes in the lymphoma cells, encoding viral proteins that play important roles in KSHV lymphomagenesis. Deregulation of the NF-kappaB pathway is an important strategy used by KSHV to promote lymphoma cell survival, and the viral protein vFLIP is essential for this process. Two other viruses that are well documented to be causally associated with lymphoid neoplasia in humans are Epstein-Barr virus (EBV/HHV-4) and human T-cell lymphotropic virus (HTLV-1). Both of these are similar to KSHV in their use of viral proteins to promote cell survival by deregulating the NF-kappaB pathway. Here we review the basic information and recent developments that have contributed to our knowledge of lymphomas caused by KSHV and other viruses. The understanding of the mechanisms of viral lymphomagenesis should lead to the identification of novel therapeutic targets and to the development of rationally designed therapies.

Kaposi's sarcoma-associated herpes virus and acquired immunodeficiency syndrome-related malignancy.

Kaposi's sarcoma-associated herpes virus (KSHV), also known as human herpes virus-8 (HHV-8), is a recently described gamma-herpes virus that has been etiologically linked to two different acquired immunodeficiency syndrome (AIDS)-related malignancies by strong epidemiologic and pathologic evidence. Infection been shown to precede and predict the development of Kapasi's sarcoma (KS) in human immunodeficiency virus (HIV)-infected patients, and viral DNA has been found in KS lesions of all types and stages. Furthermore, KSHV is a lymphotropic virus and is present in nearly all cases of primary effusion lymphoma, a rare malignancy disproportionately affecting HIV-infected individuals. KSHV is also thought to dramatically affect the incidence, type, and course of multicentric Castleman's disease, another lymphoproliferative disorder over-represented in people with AIDS. KSHV encodes many potentially oncogenic products, including several apparently pirated from the human genome. These include various chemokines, cell cycle regulatory proteins, and survival and proliferation factors. Knowledge is rapidly accumulating concerning the viral pathogenic mechanisms and host cofactors necessary for KSHV-mediated disease.

Polymerase chain reaction detection of Kaposi's sarcoma-associated herpesvirus-optimized protocols and their application to myeloma.

Since its discovery in 1994, KSHV (also called human herpesvirus-8 or HHV8) has been implicated in a variety of disorders. Although the association of KSHV with Kaposi's sarcoma (KS), primary effusion lymphoma (PEL), and multicentric Castleman's disease has been well established, its presence in some other diseases, such as multiple myeloma, remains controversial. Because most KSHV studies are based on polymerase chain reaction (PCR) analysis, the conflicting data may be attributable to variations in the methods, primer sets, and target sequences selected. To establish an efficient and reliable PCR approach for KSHV detection we designed eight sets of primers to six regions (ORFK1, ORFK2, ORFK9, ORK26, ORF72, and ORF74) of the KSHV genome using appropriate database and software. The detection sensitivity of these primers was carefully assessed and their reliability was strictly validated in a series of positive (15 KS and PEL samples) and negative (16 lymphoid tissues) controls. We found that primer sets to the ORFK9 region showed the highest sensitivity, whereas primer sets to ORFK1 and ORF74 showed the lowest sensitivity. Primer sets to ORFK9, ORF26 and ORF72 regions detected all of the positive cases, whereas other primer sets showed varying detection rates or nonspecific bands. All 16 negative controls were negative with all primer sets. However, six of 16 negative controls became positive when we used nested PCR targeting ORF26. Therefore, multiple target KSHV sequences increase the detection efficiency, while nested PCR protocols are likely to introduce false positivity. Using ORFK9, ORF26 and ORF72 primer sets, we screened bone marrow biopsies from 18 cases of multiple myeloma, and failed to detect any KSHV sequences. This finding supports the conclusion that KSHV is not associated with multiple myeloma. Indeed, our results further confirm that although KSHV is universally present in Kaposi's sarcoma and primary effusion lymphoma, it is not ubiquitious.

Kaposi's sarcoma-associated herpesvirus and human herpesvirus 8 (KSHV/HHV8)-associated lymphoma of the bowel. Report of two cases in HIV-positive men with secondary effusion lymphomas.

This report describes two cases of Kaposi's sarcoma-associated herpesvirus/human herpesvirus-8 (KSHV/HHV8)-associated lymphomas that primarily involved the large bowel and that secondarily caused malignant effusions. Involvement of the gastrointestinal tract is of interest because epidemiologic evidence suggests that KSHV/HHV-8 may be transmitted via the fecal-oral route, and KSHV/HHV8 DNA has been detected in rectal samples from HIV-positive patients. This report describes two HIV-positive men who developed primary KSHV/ HHV8-associated lymphomas of the bowel. Despite similar morphology and immunophenotype, these cases differ from most KSHV/HHV8-associated primary effusion lymphomas, which present with malignant effusions in the absence of a solid tumor mass. The spectrum of KSHV/HHV8-associated lymphomas is expanded to include a subset of primary bowel lymphomas in individuals infected with human immunodeficiency virus.

Colocalization of the viral interleukin-6 with latent nuclear antigen-1 of human herpesvirus-8 in endothelial spindle cells of Kaposi's sarcoma and lymphoid cells of multicentric Castleman's disease.

Human herpesvirus-8 (HHV-8) also called Kaposi's sarcoma-associated herpesvirus infects spindle cells in Kaposi's sarcoma (KS) and lymphoid cells in multicentric Castleman's disease (MCD). In KS cells, HHV-8 is mainly latent with the expression of latent nuclear antigen-1 (LNA-1), whereas in MCD both lytic and latent antigens are produced by lymphoid cells. We show by immunohistochemical labeling that in KS viral interleukin-6 (vIL-6) is expressed in rare spindle cells, whereas in MCD, vIL-6 is detectable in lymphoid cells around lymphoid follicles but also within the follicular dendritic reticulum cell network. The staining of apoptotic bodies with anti IL-6 antibody suggests the achievement of a complete lytic cycle in a subset of lymphoid cells. Interestingly, in MCD, some areas contained vascular spindle cells latently infected by HHV-8 on the basis of LNA-1 expression. This finding might imply that in MCD, both vascular and lymphoid cells proliferate in response to the viral infection. Double immunostaining with anti LNA-1 and anti vIL-6 in MCD and KS identifies 2 subsets of HHV-8 infected (vascular and lymphoid) cells, some with exclusive expression of LNA-1 and some with coexpression of vIL-6 and LNA-1. This suggests that in vivo the regulation of the expression vIL-6 and LNA-1 protein varies with the cell type. In addition, the detection of infected endothelial cells in MCD may indicate that these cells belong to the reservoir for HHV-8.

A distinctive composite lymphoma consisting of clonally related mantle cell lymphoma and follicle center cell lymphoma.

Although follicle center cell lymphoma and mantle cell lymphoma are both B cell non-Hodgkin's lymphomas (NHL), they are regarded as separate entities with distinct clinical, morphological, immunophenotypic and molecular characteristics. To our knowledge, the coexistence of these 2 lymphomas in the same patient has never been reported. We describe a 70-year-old woman with a long-standing history of follicle center cell lymphoma, cytological grade I, who subsequently developed a composite lymphoma consisting of well-demarcated foci of persistent follicle center cell lymphoma surrounded by mantle cell lymphoma. This morphological interpretation was supported by the presence of both bcl-1 and bcl-2 gene rearrangements, which are molecular genetic hallmarks of mantle cell lymphoma and follicle center cell lymphoma, respectively. Polymerase chain reaction (PCR) analysis for rearranged immunoglobulin heavy chain (IgH) genes showed a dominant band identical in size in microdissected tumor cells of the follicle center cell and mantle cell lymphomas. Cloning and sequence analysis of the PCR products revealed a common clone-specific IgH gene rearrangement in these 2 lymphomas. These findings suggest that this composite lymphoma represents the unusual evolution of a malignant B-cell clone that resulted in the development of 2 morphologically distinct but clonally related B-cell NHLs. These findings also show the importance of integrating morphological, immunophenotypic, and molecular data to enhance our understanding of the complex pathogenic interrelationships in lymphomagenesis.

Detection and characterization of human herpesvirus-8-infected cells in bone marrow biopsies of human immunodeficiency virus-positive patients.

We studied 15 bone marrow biopsy specimens from patients with human immunodeficiency virus infection for detection of Kaposi sarcoma herpesvirus (KSHV/HHV-8) DNA sequences by a very sensitive and specific polymerase chain reaction (PCR) assay (with 3 different sets of primers). In addition, we used immunohistochemistry with antiviral interleukin-6 (vIL-6) and anti-latent nuclear antigen-1 (LNA-1) antibodies to localize the infected cells on tissue sections. Among the 15 samples, 6 had positive PCR results with the 3 sets of primers (orf26, orf72, orf75). Interestingly, in 2 of these 6 patients (both with Kaposi sarcoma) vIL-6 and LNA-1 were detected in mononuclear lymphoid cells but not in stromal cells of the bone marrow. The detection of vIL-6--positive lymphoid cells in bone marrow suggests a homing for HHV-8--infected elements in this tissue. The local release of vIL-6 may play some role in the plasmacytosis observed in bone marrow in the acquired immunodeficiency syndrome. HUM PATHOL 32:288-291.

Cardiac arrhythmias associated with subarachnoid hemorrhage: prospective study.

This is a prospective study of cardiac arrhythmias in patients with acute subarachnoid hemorrhage (SAH) secondary to ruptured aneurysm. Twenty per cent of the patients had serious, life-threatening arrhythmias. However, 100% of the patients had some kind of cardiac arrhythmia. The arrhythmias occurred during the first 48 hours after SAH. Such arrhythmias occur in patients without overt, pre-existing heart disease, hypoxemia, or electrolyte imbalance. A prolonged Q-T interval is frequently observed in patients with SAH who develop serious ventricular arrhythmias. (Neurosurgery, 5: 675--680, 1979).

Molecular Detection of Kaposi's Sarcoma-Associated Herpesvirus/ Human Herpesvirus-8.

Kaposi's sarcoma-associated herpesvirus (KSHV), also called human herpesvirus-8 (HHV-8), is the most recently identified human herpesvirus (1). It has been found to be invariably present in Kaposi's sarcoma (KS) lesions, whether these are associated with AIDS (epidemic KS), therapeutic immunosuppression (iatrogenic KS), or high-incidence regions in Africa (endemic KS), or in its "classic" form (sporadic KS) (for reviews see refs. 2 and 3). By contrast, with few reported exceptions, it has not been found to be present in a variety of other vascular tumors and reactive conditions. A seroepidemiologic association of this virus and KS has been well documented, and it is currently accepted that KSHV plays a necessary, although not sufficient, role in the development of KS. Although diagnosis of KS is usually not difficult based on clinical and histologic features, some cases may have unusual morphology, with features overlapping those of other vascular and spindle cells proliferations. In these instances, molecular detection is useful to confirm or rule out a diagnosis of KS.

Aggressive natural killer cell lymphoma presenting as an anterior mediastinal mass in a patient with acquired immunodeficiency syndrome.

We report a case of aggressive natural killer cell lymphoma presenting as an anterior mediastinal mass in an African-American man with acquired immunodeficiency syndrome. Histologically, the anterior mediastinal mass showed a diffuse dense infiltrate of atypical intermediate-sized and large lymphoid cells, as well as scattered immunoblasts with angiocentric and angiodestructive growth and extensive zonal necrosis. Similar lymphoid infiltrates were present in the patient's lungs, spleen, and bone marrow, accompanied by extensive lymphophagocytosis. Electron microscopic and cytologic examinations showed the presence of dense cytoplasmic granules. Immunophenotyping by flow cytometry and by immunohistochemistry yielded surface markers consistent with a natural killer cell lymphoma. The Epstein-Barr virus genome and monoclonality were detected by in situ hybridization and Southern blot analysis. Polymerase chain reaction confirmed the presence of type A Epstein-Barr virus. T-cell receptor gene rearrangement could not be identified by Southern blot analysis or polymerase chain reaction. To the best of our knowledge, this is the first reported case of designated natural killer cell lymphoma from the mediastinum, as well as the first reported case of natural killer cell lymphoma in a patient with acquired immunodeficiency syndrome. This tumor disseminated early and pursued a highly aggressive course. Epstein-Barr virus may play a role in the pathogenesis of this disease.

Herpesvirus 8 inclusions in primary effusion lymphoma: report of a unique case with T-cell phenotype.

We describe a case of primary effusion lymphoma with T-cell phenotype, mixed genotype, and intranuclear herpesvirus inclusions visible with the light microscope. Cells were studied by immunohistochemical analysis, in situ hybridization, immunoglobulin and T-cell receptor gene rearrangement, and polymerase chain reaction. Primary effusion lymphoma cells with T-cell phenotype revealed herpesvirus 8 inclusions predominantly seen in apoptotic cells, suggesting that productive viral infection is associated with cell death. Clinical features were typical of primary effusion lymphoma. Cytologic, molecular genetic, and phenotypic features demonstrated a unique variant of primary effusion lymphoma.

Kaposi's sarcoma-associated herpesvirus: a lymphotropic human herpesvirus associated with Kaposi's sarcoma, primary effusion lymphoma, and multicentric Castleman's disease.

Despite extensive epidemiological evidence suggesting that Kaposi's sarcoma (KS) has an infectious origin, a specific viral association with KS had not been documented until recently, when two novel DNA fragments were identified in KS lesional tissue from a patient with the acquired immunodeficiency syndrome (AIDS). These fragments belong to a previously unidentified human herpesvirus, called KS-associated herpesvirus (KSHV), or human herpesvirus 8. Although this virus is generally absent from normal control tissues, inflammatory conditions, and a variety of tumors, it is present in most AIDS- as well as non-AIDS-related KS lesions, suggesting that it is not simply an opportunistic infection in human immunodeficiency virus (HIV)-infected patients. Furthermore, this virus is consistently present in a specific type of non-Hodgkin's lymphoma, frequently although not exclusively occurring in patients with AIDS (namely, the primary effusion lymphomas, previously called body cavity-based lymphomas). KSHV is also present in a significant proportion of cases of AIDS- and non-AIDS-related multicentric Castleman's disease. Sequence analysis has led to the identification of genes in the KSHV genome that may have important pathobiological functions, and experimental approaches have been developed to isolate, grow and transmit KSHV in vitro. An understanding of KSHV is important for evaluating its role in the pathogenesis of Kaposi's sarcoma, primary effusion lymphomas, and multicentric Castleman's disease, and to help develop better methods for the prevention and treatment of these diseases.

Molecular pathology of posttransplantation lymphoproliferative disorders.

Posttransplantation lymphoproliferative disorders (PT-LPDs) represent a heterogeneous group of Epstein-Barr virus (EBV) associated lymphoid proliferations occurring in the setting of immunosuppression associated with solid organ transplantation. Some PT-LPDs regress after a reduction in immunosuppression, whereas others progress despite aggressive therapy. Previously defined histopathologic categories do not correlate with clonality, and neither histopathology nor clonality has reliably predicted their clinical behavior. Recently, correlative clinical, morphological, and molecular genetic analysis has suggested that PT-LPDs are divisible into three distinct clinically relevant categories as follows: (1) plasmacytic hyperplasia: most commonly arise in the oropharynx or lymph nodes, are nearly always polyclonal, usually contain multiple EBV infectious events or only a minor cell population infected by a single form of EBV, and lack oncogene or tumor suppressor gene alterations; (2) polymorphic lymphoproliferative disorders: may arise in lymph nodes or extranodal sites including the gastrointestinal tract and lungs, are nearly always monoclonal based on the presence of clonal immunoglobulin gene rearrangements, usually contain a single form of EBV, and lack oncogene or tumor suppressor gene alterations; and (3) malignant lymphoma or multiple myeloma: present with widely disseminated disease frequently including the bone marrow, are monoclonal based on clonal immunoglobulin gene rearrangements, contain a single form of EBV, and contain alterations of one or more oncogenes or tumor suppressor genes (c-myc, ras, p53). Thus, proto-oncogene and tumor suppressor gene alterations appear to be associated with disease progression and an often fatal clinical outcome. Furthermore, multiple PT-LPD lesions occurring in the same individual but in multiple anatomic sites, either simultaneously or dysynchronously over time, may show distinct clonal immunoglobulin gene rearrangement patterns and evidence of infection by different forms of EBV, suggesting that each lesion represents a distinct clonal neoplasm that may show distinctive clinical behavior. Therefore, whenever possible, a biopsy of each one of the several PT-LPD lesions occurring in an individual should be obtained to derive a true assessment of the pathobiological nature and clinical aggressiveness of an individual's disease.