Antisense oligodeoxynucleotides to latent membrane protein 1 induce growth inhibition, apoptosis and Bcl-2 suppression in Epstein-Barr virus (EBV)-transformed B-lymphoblastoid cells, but not in EBV-positive natural killer cell lymphoma cells

[Clinical features and treatment outcome of patients with non-Hodgkin lymphoma-associated hemophagocytic lymphohistiocytosis]

Objective: To investigate the clinical features and effect of prognostic factors in patients with different pathological types of non-Hodgkin lymphoma-associated hemophagocytic lymphohistiocytosis. Methods: We collected and analyzed the clinical data of 89 patients with non-Hodgkin lymphoma-associated hemophagocytic lymphohistiocytosis who were treated at Huadong Hospital from March 2013 to May 2020. The data were analyzed via log-rank and Cox multivariate analyses. Results: The median overall survival time of the 89 cases was 10.2 months. Patients with B-cell lymphoma-associated hemophagocytic lymphohistiocytosis did not reach the median overall survival time. The median overall survival times of T-cell lymphoma-associated hemophagocytic lymphohistiocytosis and NK-cell lymphoma-associated hemophagocytic lymphohistiocytosis were 10.2 and 3.0 months, respectively. The pathological type of non-Hodgkin lymphoma (OS: P=0041, PFS: P=0.015) , ECOG score ≥ 3 (OS: P=0.031, PFS: P=0.030) , hematopoietic stem cell transplantation (OS: P=0.005, PFS: P=0.040) , lymphadenopathy (OS: P=0.007, PFS: P=0.012) , and splenomegaly (OS: P=0.276, PFS: P=0.324) were related to the overall survival and progression-free survival of patients with non-Hodgkin lymphoma-associated hemophagocytic lymphohistiocytosis. Splenectomy could improve the prognosis of patients with lymphoma-associated hemophagocytic lymphohistiocytosis, especially T-cell lymphoma-associated hemophagocytic lymphohistiocytosis. Conclusion: The clinical characteristics of patients with different pathological types of non-Hodgkin lymphoma-associated hemophagocytic lymphohistiocytosis were similar but were different in the overall survival rate and the effect of prognostic factors. We suggested that patients with non-Hodgkin lymphoma-associated hemophagocytic lymphohistiocytosis should receive more than combined chemotherapy. To improve the prognosis and survival rate of patients, those with B-cell lymphoma-associated hemophagocytic lymphohistiocytosis and NK-cell lymphoma-associated hemophagocytic lymphohistiocytosis promptly require hematopoietic stem cell transplantation. Moreover, patients with T-cell lymphoma-associated hemophagocytic lymphohistiocytosis should consider splenectomy.

EBV-Associated Lymphoproliferative Disorders: Update in Classification

Although about 90% of the world's population is infected by EBV only a small subset of the related infections result in neoplastic transformation. EBV is a versatile oncogenic agent involved in a multitude of hematopoietic, epithelial, and mesenchymal neoplasms, but the precise role of EBV in the pathogenesis of many of the associated lymphoid/histiocytic proliferations remains hypothetical or not completely understood. Additional studies and use of evolving technologies such as high-throughput next-generation sequencing may help address this knowledge gap and may lead to enhanced diagnostic assessment and the development of potential therapeutic interventions.

Molecular pathogenic pathways in extranodal NK/T cell lymphoma

Extranodal NK/T cell lymphoma, nasal type (ENKTL) is an aggressive malignancy with a dismal prognosis. Although L-asparaginase-based chemotherapy has resulted in improved response rates, relapse occurs in up to 50% of patients with disseminated disease. There is hence an urgent need for effective targeted therapy, especially for patients with relapsed or refractory disease. Novel insights gleaned from high-throughput molecular and genomic profiling studies in recent years have contributed significantly to the understanding of the molecular biology of ENKTL, which exemplifies many of the hallmarks of cancer. Deregulated pro-proliferative signaling pathways, such as the Janus-associated kinase/signal transducer and activator of transcription (JAK/STAT), platelet-derived growth factor (PDGF), Aurora kinase, MYC, and NF-κB, have been identified as potential therapeutic targets. The discovery of the non-canonical function of EZH2 as a pro-proliferative transcriptional co-activator has shed further light on the pathogenesis of ENKTL. Loss of key tumor suppressor genes located on chromosome 6q21 also plays an important role. The best-studied examples include PR domain zinc finger protein 1(PRDM1), protein tyrosine phosphatase kappa (PTPRK), and FOXO3. Promoter hypermethylation has been shown to result in the downregulation of other tumor suppressor genes in ENKTL, which may be potentially targeted through hypomethylating agents. Deregulation of apoptosis through p53 mutations and upregulation of the anti-apoptotic protein, survivin, may provide a further growth advantage to this tumor. A deranged DNA damage response as a result of the aberration of ataxia telangiectasia-related (ATR) kinases can lead to significant genomic instability and may contribute to chemoresistance of ENKTL. Recently, immune evasion has emerged as a critical pathway for survival in ENKTL and may be a consequence of HLA dysregulation or STAT3-driven upregulation of programmed cell death ligand 1 (PD-L1). Immunotherapy via inhibition of programmed cell death 1 (PD-1)/PD-L1 checkpoint signaling holds great promise as a novel therapeutic option. In this review, we present an overview of the key molecular and pathogenic pathways in ENKTL, organized using the framework of the "hallmarks of cancer" as described by Hanahan and Weinberg, with a focus on those with the greatest translational potential.

Epstein-Barr virus (EBV)-associated lymphoid proliferations, a 2018 update

Epstein-Barr virus (EBV) has been linked to many human neoplasms including hematopoietic, epithelial, and mesenchymal tumors. Since our original review of EBV-associated lymphoproliferative disorders in 2007, many advances and developments have been reported. In this review, we will examine the recent advances in EBV-associated lymphoid/histiocytic proliferations, dividing them into reactive, B cell, T/NK cell, immunodeficiency-related, and histiocytic/dendritic cell proliferations.

The Modulation of Apoptotic Pathways by Gammaherpesviruses

Apoptosis or programmed cell death is a tightly regulated process fundamental for cellular development and elimination of damaged or infected cells during the maintenance of cellular homeostasis. It is also an important cellular defense mechanism against viral invasion. In many instances, abnormal regulation of apoptosis has been associated with a number of diseases, including cancer development. Following infection of host cells, persistent and oncogenic viruses such as the members of the Gammaherpesvirus family employ a number of different mechanisms to avoid the host cell’s “burglar” alarm and to alter the extrinsic and intrinsic apoptotic pathways by either deregulating the expressions of cellular signaling genes or by encoding the viral homologs of cellular genes. In this review, we summarize the recent findings on how gammaherpesviruses inhibit cellular apoptosis via virus-encoded proteins by mediating modification of numerous signal transduction pathways. We also list the key viral anti-apoptotic proteins that could be exploited as effective targets for novel antiviral therapies in order to stimulate apoptosis in different types of cancer cells.

Epstein-Barr virus interactions with the Bcl-2 protein family and apoptosis in human tumor cells

Epstein-Barr virus (EBV), a human gammaherpesvirus carried by more than 90% of the world's population, is associated with malignant tumors such as Burkitt's lymphoma (BL), Hodgkin lymphoma, post-transplant lymphoma, extra-nodal natural killer/T cell lymphoma, and nasopharyngeal and gastric carcinomas in immune-compromised patients. In the process of infection, EBV faces challenges: the host cell environment is harsh, and the survival and apoptosis of host cells are precisely regulated. Only when host cells receive sufficient survival signals may they immortalize. To establish efficiently a lytic or long-term latent infection, EBV must escape the host cell immunologic mechanism and resist host cell apoptosis by interfering with multiple signaling pathways. This review details the apoptotic pathway disrupted by EBV in EBV-infected cells and describes the interactions of EBV gene products with host cellular factors as well as the function of these factors, which decide the fate of the host cell. The relationships between other EBV-encoded genes and proteins of the B-cell leukemia/lymphoma (Bcl) family are unknown. Still, EBV seems to contribute to establishing its own latency and the formation of tumors by modifying events that impact cell survival and proliferation as well as the immune response of the infected host. We discuss potential therapeutic drugs to provide a foundation for further studies of tumor pathogenesis aimed at exploiting novel therapeutic strategies for EBV-associated diseases.

Monocytes enhance cell proliferation and LMP1 expression of nasal natural killer/T-cell lymphoma cells by cell contact-dependent interaction through membrane-bound IL-15

Nasal natural killer (NK)/T-cell lymphoma (NNKTL) is an Epstein-Barr virus (EBV)-related malignancy with poor prognosis and has distinct histological features characterized by angiocentric and polymorphous lymphoreticular infiltrates including inflammatory cells such as granulocytes, monocytes, macrophages and lymphocytes. Here, we show that the monocytes enhance proliferation as well as LMP1 expression of NNKTL cells by cell contact-dependent interaction through membrane-bound interleukin (IL)-15. We used two EBV-positive NK-cell lines, SNK6 and KAI3, which originated from two patients-SNK6 from a patient with NNKTL and KAI3 from a patient with a severe mosquito allergy. We cocultured the cell lines with granulocytes or monocytes and examined whether proliferation, survival and LMP1 expression of the cells changed. Although cocultured granulocytes did not affect proliferation, survival or LMP1 expression of the cells, cocultured monocytes enhanced both proliferation and LMP1 expression in a dose-dependent manner. These phenomena were not seen when monocytes were placed in a separate chamber. Moreover, the monocyte-inducible proliferation and LMP1 expression were inhibited by treatment with an antibody against IL-15. Furthermore, production of interferon-gamma-inducible protein (IP)-10 were enhanced by coculture with monocytes and were inhibited by the antibody. Immunohistological studies confirmed that a number of infiltrating CD14-positive monocytes contacted CD56-positive lymphoma cells in all of 20 NNKTL tissues tested. These results suggest that monocytes enhance cell growth as well as LMP1 expression of NNKTL cells by cell contact-dependent interaction through membrane-bound IL-15. In the microenvironment of NNKTL tissue, a positive feedback loop of interaction between lymphoma cells and monocytes may be present and contribute to lymphoma progression.

Epstein-Barr virus–associated lymphoproliferative disorders

Epstein-Barr virus (EBV) is a member of the human herpesvirus family that was initially isolated from a cultured Burkitt lymphoma cell line by Epstein et al in 1964. Subsequent studies have proven that it is the causative agent in most cases of infectious mononucleosis. Primary infection is usually asymptomatic in childhood; but in adulthood, it is associated with a self-limiting infectious mononucleosis syndrome in approximately one third of the cases. EBV has been linked to many human neoplasms including hematopoietic, epithelial, and mesenchymal tumors. In this review, we will only discuss the EBV-associated lymphoproliferative disorders, dividing them into B-cell, T/NK-cell, and HIV-related lymphoproliferative disorders.

Concomitant increase of LMP1 and CD25 (IL-2-receptor alpha) expression induced by IL-10 in the EBV-positive NK lines SNK6 and KAI3

Extranodal, nasal NK/T-cell lymphomas are regularly Epstein-Barr virus (EBV)-positive, with a type II latency pattern, expressing thus EBNA-1 and LMP1. The contribution of EBV to the tumor development is not known. Similarly to normal natural killer (NK) cells, cell lines derived from malignancies with a NK phenotype require IL-2 for in vitro proliferation. In our effort to explore the contribution of EBV, particularly the role of the LMP1 protein, to the pathogenesis of the NK lymphoma we found that its expression, studied in the NK-lines SNK6 and KAI3, depended on the supply of IL-2 or other cytokines. In the absence of IL-2 other cytokines, such as IL-10 and IFN-gamma, could maintain LMP1, but the cells did not proliferate. When grown in IL-2, the SNK6 cells produced IL-10 and IFN-gamma, and these cytokines mediated the expression of LMP1. IL-10 treatment enhanced, while IFN-gamma receptor blocking antibody reduced, the expression of CD25 and CD54 in the EBV-positive, but not in the EBV-negative lines. IL-10 treated cells required lower amount of IL-2 for proliferation compared to the untreated cells. This effect was seen only with the EBV-positive NK lines in which LMP1 and CD25 were concomitantly upregulated. By this mechanism EBV could have an important role in the development of NK lymphoma since the inflammatory component in the tumor tissue can provide these cytokines.

A Preferential Role for STAT5, not Constitutively Active STAT3, in Promoting Survival of a Human Lymphoid Tumor

STATs are believed to play key roles in normal and abnormal cell function. In the present work, we investigated the role of STATs in an IL-2-responsive human lymphoblastic lymphoma-derived cell line, YT. Only STAT3 was found constitutively tyrosine phosphorylated, but not other STATs. Hyperactive STAT3 was not attributable to a pre-existing intermediate affinity IL-2R complex and/or hyperactive Jak activity. Depletion of STAT3 protein expression reduced tumor cell viability with protracted kinetics (72-96 h), while TUNEL assays demonstrated cell death occurred via apoptosis. Interestingly, depletion of STAT5 in this same tumor induced more pronounced cell death compared with STAT3 depletion (24 h). Although IL-2 was able to rescue STAT3-depleted cells from death, it could not compensate for the loss of STAT5. To determine the prosurvival function of STAT3 vs STAT5 within the same tumor model, genes were profiled in STAT3- or STAT5-depleted YT cells by apoptosis-specific microarrays. Several differentially expressed genes were identified. Interestingly, those genes involved in NF-kappaB regulation, such as TNFR-associated factors 2 and 5 and B cell leukemia/lymphoma 10, were readily decreased upon STAT5, but not STAT3, depletion as validated by quantitative RT-PCR. These results suggest that STAT5 and, to a lesser extent, hyperactive STAT3 provide preferential and critical cell survival signals for certain human lymphoid tumors, indicating that nonhyperactive STATs should be considered as therapeutic targets for abrogating tumorigenesis.

Marek's disease is a natural model for lymphomas overexpressing Hodgkin's disease antigen (CD30)

Animal models are essential for elucidating the molecular mechanisms of carcinogenesis. Hodgkin's and many diverse non-Hodgkin's lymphomas overexpress the Hodgkin's disease antigen CD30 (CD30(hi)), a tumor necrosis factor receptor II family member. Here we show that chicken Marek's disease (MD) lymphoma cells are also CD30(hi) and are a unique natural model for CD30(hi) lymphoma. Chicken CD30 resembles an ancestral form, and we identify a previously undescribed potential cytoplasmic signaling domain conserved in chicken, human, and mouse CD30. Our phylogeneic analysis defines a relationship between the structures of human and mouse CD30 and confirms that mouse CD30 represents the ancestral mammalian gene structure. CD30 expression by MD virus (MDV)-transformed lymphocytes correlates with expression of the MDV Meq putative oncogene (a c-Jun homologue) in vivo. The chicken CD30 promoter has 15 predicted high-stringency Meq-binding transcription factor recognition motifs, and Meq enhances transcription from the CD30 promoter in vitro. Plasma proteomics identified a soluble form of CD30. CD30 overexpression is evolutionarily conserved and defines one class of neoplastic transformation events, regardless of etiology. We propose that CD30 is a component of a critical intracellular signaling pathway perturbed in neoplastic transformation. Specific anti-CD30 Igs occurred after infection of genetically MD-resistant chickens with oncogenic MDV, suggesting immunity to CD30 could play a role in MD lymphoma regression.

Suppression of Epstein-Barr virus-encoded latent membrane protein-1 by RNA interference inhibits the metastatic potential of nasopharyngeal carcinoma cells

Nasopharyngeal carcinoma (NPC) is a highly metastatic tumor characterized by close association with EBV. Of the EBV-encoded products, latent membrane protein-1 (LMP-1) is thought to be the only oncoprotein playing an essential role in cell transformation as well as tumor metastasis. In this study, we tested the effect of suppressing LMP-1 by RNA interference (RNAi) on the proliferative and metastatic potentials of an EBV-positive NPC cell line, C666. We showed that stably suppressing LMP-1 by short hairpin RNA (shRNA) plasmid significantly altered cell motility, substratum adhesion, and transmembrane invasion ability. However, it has little effect on the rate of cell growth and cell cycle control. These results demonstrated the effectiveness of RNAi in suppressing LMP-1, supporting an important role of LMP-1 in NPC metastasis, and suggested a potential application of RNAi-mediated therapeutic strategy for EBV-related NPC.

Diagnosis and treatment of Epstein-Barr virus-associated natural killer cell lymphoproliferative disease

Epstein-Barr virus (EBV) exhibits tropism for both lymphocytes and epithelial cells and can induce both replicative (productive/lytic) and latent (persistent) infections that result in a variety of human diseases. With regard to lymphocytes, latent EBV infection is linked to development of heterogeneous lymphoproliferative disease (LPD), such as B-cell LPD and T-cell/natural killer cell (T/NK cell) LPD. Unlike B-cell LPD, LPD derived from T-cells and NK cells sometimes has overlapping clinical symptoms, as well as histologic and immunophenotypic features, because both types of cells are derived from a common precursor. However, determination of cell lineage is important in classification of lymphoid neoplasms, and combined modern techniques allows us to distinguish NK cell LPD from T-cell LPD in most instances. Because NK cell LPD seems to be heterogeneous in terms of clinical features, prognosis, and diagnosis and has a monoclonal or polyclonal (or oligoclonal) nature, this review attempts to clarify recent research and clinical findings and to establish diagnostic and therapeutic strategies.

Human monocytic cell lines transformed in vitro by Epstein-Barr virus display a type II latency and LMP-1-dependent proliferation

Epstein-Barr virus (EBV) classically infects and transforms B lymphocytes in vitro, yielding lymphoblastoid cell lines (LCLs). In contrast to other herpesviruses, EBV is not described as an infectious agent for monocytes. However, recent papers described in vitro infection of monocytes leading to abortive or transient viral expression. In the present study, we report the characterization of E1, a monocytic cell line infected and transformed by EBV. This cell line was derived from an LCL by a drastic electroporation and selection of neomycin-resistant cells, unfavorable to B-cell outgrowth. E1 expressed surface molecules of monocytic lineage (CD14, major histocompatibility complex class II, and CD80) and the c-fms gene, a highly specific marker for the monocytic lineage. This cell line is able to phagocytose and secrete proinflammatory monokines tumor necrosis factor alpha, interleukin-6 (IL-6), and IL-8. E1 cells are tumorigenic after injection in nude mice, and a monocytic cell line obtained from one of these tumors (TE1) displayed immunophenotype and functional properties similar to those of E1. We detected the presence of the EBV genome in both cell lines, as well as expression of the EBNA-1 and LMP-1, but not EBNA-2, viral genes, characteristic of a type II latency. LMP-1 influences the phenotype of these monocytic cell lines, as demonstrated by down-regulation of cell proliferation and membrane intercellular adhesion molecule 1 expression due to an LMP-1 antisense strategy. This is the first description of a latently infected human monocytic cell line and the first direct demonstration of an instrumental role for LMP-1 in the proliferation of EBV-transformed cell lines expressing a type II latency.

Antisense to Epstein Barr Virus-encoded LMP1 does not affect the transcription of viral and cellular proliferation-related genes, but induces phenotypic effects on EBV-transformed B lymphocytes

It is generally accepted that Epstein-Barr virus (EBV) latent genes EBNA-2, EBNA-3A, -3C, EBNA-LP and LMP1 are essential for growth transformation and immortalization of B lymphocytes. Among these genes, LMP1 plays a key role in the survival and dissemination of the infected B cells by inducing anti-apoptotic genes and surface expression of several activation antigens and adhesion molecules. We have previously shown that antisense oligodeoxynucleotides directed to LMP1 mRNA, effectively suppress LMP1 gene expression and substantially reduce B95.8 cell proliferation. In this study, we have used antisense LMP1 oligomers to investigate whether LMP1 suppression might influence the expression of latent EBV genes with oncogenic potential, anti-apoptotic genes, or affect the phenotype of EBV-infected B95.8 cells. Our data show that LMP1 suppression does not affect the transcription of EBNA-2, EBNA-3A, -3B and -3C genes, or that of bcl-2 and mcl-1 anti-apoptotic genes. In contrast, consistent modifications in the expression of CD39, CD54, CD23, CD11 and CD10 molecules were observed in B95.8 cells after treatment with antisense LMP1. Our findings support the possibility for using LMP1 antisense oligomers as therapeutics in EBV-associated tumors.