Anti-tumor effects of suberoylanilide hydroxamic acid on Epstein-Barr virus-associated T cell and natural killer cell lymphoma

Exploring the anti-EBV potential of suberoylanilide hydroxamic acid: Induction of apoptosis in infected cells through suppressing BART gene expression and inducing lytic infection

Epstein-Barr virus (EBV) is linked to lymphoma and epithelioma but lacks drugs specifically targeting EBV-positive tumors. BamHI A Rightward Transcript (BART) miRNAs are expressed in all EBV-positive tumors, suppressing both lytic infection and host cell apoptosis. We identified suberoylanilide hydroxamic acid (SAHA), an inhibitor of histone deacetylase enzymes, as an agent that suppresses BART promoter activity and transcription of BART miRNAs. SAHA treatment demonstrated a more pronounced inhibition of cell proliferation in EBV-positive cells compared to EBV-negative cells, affecting both p53 wild-type and mutant gastric epithelial cells. SAHA treatment enhanced lytic infection in wild-type EBV-infected cells, while also enhancing cell death in BZLF1-deficient EBV-infected cells. It reduced BART gene expression by 85% and increased the expression of proapoptotic factors targeted by BART miRNAs. These findings suggest that SAHA not only induces lytic infection but also leads to cell death by suppressing BART miRNA transcription and promoting the apoptotic program.

Formation and culture of cell spheroids by using magnetic nanostructures resembling a crown of thorns

In contrast to traditional two-dimensional cell-culture conditions, three-dimensional (3D) cell-culture models closely mimic complexin vivoconditions. However, constructing 3D cell culture models still faces challenges. In this paper, by using micro/nano fabrication method, including lithography, deposition, etching, and lift-off, we designed magnetic nanostructures resembling a crown of thorns. This magnetic crown of thorns (MCT) nanostructure enables the isolation of cells that have endocytosed magnetic particles. To assess the utility of this nanostructure, we used high-flux acquisition of Jurkat cells, an acute-leukemia cell line exhibiting the native phenotype, as an example. The novel structure enabled Jurkat cells to form spheroids within just 30 min by leveraging mild magnetic forces to bring together endocytosed magnetic particles. The size, volume, and arrangement of these spheroids were precisely regulated by the dimensions of the MCT nanostructure and the array configuration. The resulting magnetic cell clusters were uniform in size and reached saturation after 1400 s. Notably, these cell clusters could be easily separated from the MCT nanostructure through enzymatic digestion while maintaining their integrity. These clusters displayed a strong proliferation rate and survival capabilities, lasting for an impressive 96 h. Compared with existing 3D cell-culture models, the approach presented in this study offers the advantage of rapid formation of uniform spheroids that can mimicin vivomicroenvironments. These findings underscore the high potential of the MCT in cell-culture models and magnetic tissue enginerring.

Treatment Advances in EBV Related Lymphoproliferative Diseases

Epstein Barr virus (EBV) can affect 90% of the human population. It can invade B lymphocytes, T lymphocytes and natural killer cells of the host and remain in the host for life. The long latency and reactivation of EBV can cause malignant transformation, leading to various lymphoproliferative diseases (LPDs), including EBV-related B-cell lymphoproliferative diseases (EBV-B-LPDs) (for example, Burkitt lymphoma (BL), classic Hodgkin's lymphoma (cHL), and posttransplantation and HIV-related lymphoproliferative diseases) and EBV-related T-cell lymphoproliferative diseases (EBV-T/NK-LPDs) (for example, extranodal nasal type natural killer/T-cell lymphoma (ENKTCL), aggressive NK cell leukaemia (ANKL), and peripheral T-cell lymphoma, not otherwise specified (PTCL-NOS). EBV-LPDs are heterogeneous with different clinical features and prognoses. The treatment of EBV-LPDs is usually similar to that of EBV-negative lymphoma with the same histology and can include chemotherapy, radiotherapy, and hematopoietic stem cell transplant (HSCT). However, problems such as serious toxicity and drug resistance worsen the survival prognosis of patients. EBV expresses a variety of viral and lytic proteins that regulate cell cycle and death processes and promote the survival of tumour cells. Based on these characteristics, a series of treatment strategies for EBV in related malignant tumours have been developed, such as monoclonal antibodies, immune checkpoint inhibitors, cytotoxic T lymphocytes (CTLs) and epigenetic therapy. These new individualized therapies can produce highly specific killing effects on tumour cells, and nontumour cells can be protected from toxicity. This paper will focus on the latest progress in the treatment of EBV-LPDs based on pathological mechanisms.

Molecular Basis of Epstein-Barr Virus Latency Establishment and Lytic Reactivation

Epstein–Barr virus (EBV) is a causative agent of infectious mononucleosis and several types of cancer. Like other herpesviruses, it establishes an asymptomatic, life-long latent infection, with occasional reactivation and shedding of progeny viruses. During latency, EBV expresses a small number of viral genes, and exists as an episome in the host–cell nucleus. Expression patterns of latency genes are dependent on the cell type, time after infection, and milieu of the cell (e.g., germinal center or peripheral blood). Upon lytic induction, expression of the viral immediate-early genes, BZLF1 and BRLF1, are induced, followed by early gene expression, viral DNA replication, late gene expression, and maturation and egress of progeny virions. Furthermore, EBV reactivation involves more than just progeny production. The EBV life cycle is regulated by signal transduction, transcription factors, promoter sequences, epigenetics, and the 3D structure of the genome. In this article, the molecular basis of EBV latency establishment and reactivation is summarized.

Chronic active Epstein-Barr virus infection progresses to aggressive NK cell leukemia with a poor prognosis

Epstein-Barr virus (EBV) associated T/NK-cell lymphoproliferative diseases (EBV-T/NK-LPDs) are a cluster of diseases that include chronic active EBV infection (CAEBV) and aggressive NK cell leukemia (ANKL). The pathogenesis of EBV-T/NK-LPDs is largely unclear and the treatment is difficult and in most cases a hematopoietic stem cell transplantation is needed. Hemophagocytic lymphohistiocytosis (HLH) is known to affect the prognosis of patients with EBV-T/NK-LPDs. This study reports a case of a 20-year-old male patient with repeated infectious mononucleosis (IM)-like symptoms such as high fever, splenomegaly, lymphadenopathy for more than two years. The patient had a high EBV-DNA load (NK cells were the main target cells). He was first diagnosed as CAEBV. However, the disease gradually progressed and the patient developed with high ferritin, phagocytosis and monoclonal NK cells in bone marrow, pancytopenia, increased cytokines, and elevated expression of Ki-67. Also, his NK cells had abnormal immunophenotypes and impaired function. The patient had a typical clinical course of progression from CAEBV to ANKL, accompanied by HLH complications and a poor prognosis. Herein, the detailed diagnostic and differential diagnostic process of EBV infection was shown in this report.

NK-/T-cell lymphomas

Natural killer/T-cell lymphoma (NKTL) is a sub-type of Epstein-Barr virus (EBV)-related non-Hodgkin lymphomas common in Asia and Latin America but rare elsewhere. Its pathogenesis is complex and incompletely understood. Lymphoma cells are transformed from NK- or T-cells, sometimes both. EBV-infection and subsequent genetic alterations in infected cells are central to NKTL development. Hemophagocytic syndrome is a common complication. Accurate staging is important to predict outcomes but there is controversy which system is best. More than two-thirds of NKTL lympohmas are localized at diagnosis, are frequently treated with radiation therapy only and have 5-year survival of about 70 percent. Persons with advanced NKTLs receive radiation therapy synchronously or metachronously with diverse multi-drug chemotherapy typically including L-asparginase with 5-year survival of about 40 percent. Some persons with widespread NKTL receive chemotherapy only. There are few data on safety and efficacy of high-dose therapy and a haematopoietic cell autotransplant. Immune therapies, histone deacetylase (HDAC)-inhibitors and other drugs are in early clinical trials. There are few randomized controlled clinical trials in NKTLs and no therapy strategy is clearly best; more effective therapy(ies) are needed. Some consensus recommendations are not convincingly evidence-based. Mechanisms of multi-drug resistance are considered. We discuss these issues including recent advances in our understanding of and therapy of NKTLs.

African swine fever virus replication events and cell nucleus: New insights and perspectives

African swine fever (ASF) is currently matter for major concerns in global swine industry as it is highly contagious and causes acute fatal haemorrhagic fever in domestic pigs and wild boar. The absence of effective vaccines and treatments pushes ASF control to relay on strict sanitary and stamping out measures with costly socio-economic impacts. The current epidemic scenario of fast spreading throughout Asiatic countries impels further studies on prevention and combat strategies against ASF. Herein we review knowledge on African Swine Fever Virus (ASFV) interactions with the host cell nucleus and on the functional properties of different viral DNA-replication related proteins. This entails, the confirmation of an intranuclear viral DNA replication phase, the characterization of cellular DNA damage responses (DDR), the subnuclear compartments disruption due to viral modulation, and the unravelling of the biological role of several viral proteins (A104R, I215 L, P1192R, QP509 L and Q706 L), so to contribute to underpin rational strategies for vaccine candidates development.

Advances in the treatment of extranodal NK/T-cell lymphoma, nasal type

Extranodal natural killer/T-cell lymphoma, nasal type (ENKL) is a subtype of mature T- and natural killer cell lymphomas characterized by its association with Epstein-Barr virus and extranodal involvement. Although there is geographic variance in the frequency of ENKL, its clinical features are similar between Western countries and endemic areas, such as East Asia. Anthracycline-containing chemotherapy is not recommended to treat ENKL. No standard treatment has been established based on the results of randomized controlled trials. In patients with localized disease, radiotherapy is a core component of the recommended first-line therapy. Radiotherapy administered at 50 to 54 Gy, extended involved-site radiotherapy considering tumor invasiveness, and the use of intensity modulated radiation therapy or volumetric modulated arc therapy are associated with efficacy of radiotherapy. Although the use of concurrent chemoradiotherapy has been supported by the results of clinical trials, accumulating evidence supports the use of sequential chemoradiotherapy with non-anthracycline-containing regimens that include l-asparaginase and/or platinum anticancer agents. l-asparaginase-containing chemotherapy is a key component of first-line treatments for systemic ENKL. Hematopoietic stem cell transplantation is recommended as a front-line consolidation therapy for newly diagnosed advanced-stage ENKL. Newer agents including immune checkpoint inhibitors are being investigated for treating ENKL. In this modern ENKL treatment era, multidisciplinary efforts are needed to identify the best timing and sequencing of radiotherapy, l-asparaginase, platinum, newer agents, and hematopoietic stem cell transplantation.

CMV70-3P miRNA contributes to the CMV mediated glioma stemness and represents a target for glioma experimental therapy

Glioblastoma multiforme (GBM) is a rapidly progressive brain tumor with a median survival of 15–19 months. Therapeutic resistance and recurrence of the disease is attributed to cancer stem cells (CSC). Here, we report that CMV70-3P miRNA encoded by CMV increases GBM CSC stemness. Inhibition of CMV70-3P expression using oligo inhibitors significantly attenuated the ability of primary glioma cells to proliferate and form neurospheres. At the molecular level, we show that CM70-3P increases expression of cellular SOX2. Collectively, these findings indicate that CMV70-3P is a potential regulator of CMV- mediated glioma progression and cancer stemness.

[Advances in application of Jurkat cell model in research on infectious diseases]

Infectious diseases can be caused by multiple pathogens, which can produce specific immune response in human body. The immune response produced by T cells is cellular immunity, which plays an important role in the anti-infection process of human body, and can participate in immunological protection and cause immunopathology. The outcome of various infectious diseases is closely related to cellular immune function, especially the function of T cells. Jurkat cells belong to the human acute T lymphocyte leukemia cell line. Jurkat cell model can simulate the function T lymphocytes, so it is widely used in the in vitro studies of T cell signal transduction, cytokines, and receptor expression, and can provide reference and guidance for the treatment of various infectious diseases and the research on their pathogenesis. The Jurkat cell model has been widely used in the in vitro studies of viral diseases and atypical pathogens, but parasitic infection studies using the Jurkat cell model are still rare. This article reviews advances in the application of Jurkat cell model in the research on infectious diseases.

Overview of EBV-Associated T/NK-Cell Lymphoproliferative Diseases

Epstein-Barr virus-associated T/natural killer-cell lymphoproliferative diseases (EBV-T/NK-LPDs) are a group of rare diseases resulting from ectopic infection of T or natural killer (NK) lymphocytes with Epstein-Barr virus (EBV). EBV-T/NK-LPDs include chronic active EBV infection, EBV-associated hemophagocytic lymphohistiocytosis, hydroa vacciniforme-like lymphoproliferative disease, and severe mosquito bite allergy. Extra-nodal NK/T-cell lymphoma-nasal type and aggressive NK-cell leukemia can also be included in this broad spectrum. Currently, the etiology of EBV-T/NK-LPDs is unknown and no curative therapy has been established, except for hematopoietic stem cell transplantation. While most cases of EBV-T/NK-LPDs have been documented in specific areas of the world, they have also been documented more broadly across East Asia and Latin America. Consequently, active research and discussion of EBV-T/NK-LPDs are both necessary and important within the extensive international community of scientists and clinicians, to elucidate their etiology and develop a standard therapy.

Growth-suppressive effect of suberoylanilide hydroxamic acid (SAHA) on human oral cancer cells

PURPOSE

The histone deacetylase (HDAC) inhibitor suberoylanilide hydroxamic acid (SAHA) has been reported to exhibit anticancer activities in various cancer cell types, but as yet there are few reports on the anticancer effects of SAHA in oral squamous cell carcinoma (OSCC)-derived cells and xenograft models.

METHODS

The anti-proliferative and apoptotic activities of SAHA were assessed in human HSC-3 and HSC-4 (OSCC)-derived cell lines and JB6 normal mouse skin-derived epidermal cells using histone acetylation, soft agar colony formation, trypan blue exclusion, 4'-6-diamidino-2-phenylindole (DAPI) staining, Live/Dead viability/cytotoxicity and Western blot analyses.

RESULTS

We found that SAHA treatment resulted in hyperacetylation of histones H2A and H3 and a concomitant decrease in the viability of HSC-3 and HSC-4 cells. SAHA also significantly inhibited the neoplastic transformation of JB6 cells treated with TPA, whereas the viability of these cells was not affected by this treatment. Additionally, we found that SAHA suppressed the anchorage-independent growth (colony forming capacity in soft agar) of HSC-3 and HSC-4 cells. DAPI staining, Live/Dead and Western blot analyses revealed that SAHA can induce caspase-dependent apoptosis in HSC-3 and HSC-4 cells. We also found that SAHA treatment led to inhibition of ERK phosphorylation, and that two MEK inhibitors potentiated SAHA-mediated apoptosis. Okadaic acid treatment inhibited SAHA-mediated apoptosis in both the HSC-3 and HSC-4 cell lines, wheras SAHA induced a profound in vivo inhibition of tumor growth in HSC-3 xenografts.

CONCLUSIONS

Our results indicate that the ERK signaling pathway may constitute a critical denominator of SAHA-induced apoptosis in OSCC-derived cells and that SAHA may have therapeutic potential for OSCC.

Alterations of Nuclear Architecture and Epigenetic Signatures during African Swine Fever Virus Infection

Viral interactions with host nucleus have been thoroughly studied, clarifying molecular mechanisms and providing new antiviral targets. Considering that African swine fever virus (ASFV) intranuclear phase of infection is poorly understood, viral interplay with subnuclear domains and chromatin architecture were addressed. Nuclear speckles, Cajal bodies, and promyelocytic leukaemia nuclear bodies (PML-NBs) were evaluated by immunofluorescence microscopy and Western blot. Further, efficient PML protein knockdown by shRNA lentiviral transduction was used to determine PML-NBs relevance during infection. Nuclear distribution of different histone H3 methylation marks at lysine’s 9, 27 and 36, heterochromatin protein 1 isoforms (HP1α, HPβ and HPγ) and several histone deacetylases (HDACs) were also evaluated to assess chromatin status of the host. Our results reveal morphological disruption of all studied subnuclear domains and severe reduction of viral progeny in PML-knockdown cells. ASFV promotes H3K9me3 and HP1β foci formation from early infection, followed by HP1α and HDAC2 nuclear enrichment, suggesting heterochromatinization of host genome. Finally, closeness between DNA damage response factors, disrupted PML-NBs, and virus-induced heterochromatic regions were identified. In sum, our results demonstrate that ASFV orchestrates spatio-temporal nuclear rearrangements, changing subnuclear domains, relocating Ataxia Telangiectasia Mutated Rad-3 related (ATR)-related factors and promoting heterochromatinization, probably controlling transcription, repressing host gene expression, and favouring viral replication.

The heat shock protein 90 inhibitor BIIB021 suppresses the growth of T and natural killer cell lymphomas

Epstein-Barr virus (EBV), which infects not only B cells but also T and natural killer (NK) cells, is associated with a variety of lymphoid malignancies. Because EBV-associated T and NK cell lymphomas are refractory and resistant to conventional chemotherapy, there is a continuing need for new effective therapies. EBV-encoded “latent membrane protein 1” (LMP1) is a major oncogene that activates nuclear factor kappa B (NF-κB), c-Jun N-terminal kinase (JNK), and phosphatidylinositol 3-kinase signaling pathways, thus promoting cell growth and inhibiting apoptosis. Recently, we screened a library of small-molecule inhibitors and isolated heat shock protein 90 (Hsp90) inhibitors as candidate suppressors of LMP1 expression. In this study, we evaluated the effects of BIIB021, a synthetic Hsp90 inhibitor, against EBV-positive and -negative T and NK lymphoma cell lines. BIIB021 decreased the expression of LMP1 and its downstream signaling proteins, NF-κB, JNK, and Akt, in EBV-positive cell lines. Treatment with BIIB021 suppressed proliferation in multiple cell lines, although there was no difference between the EBV-positive and -negative lines. BIIB021 also induced apoptosis and arrested the cell cycle at G1 or G2. Further, it down-regulated the protein levels of CDK1, CDK2, and cyclin D3. Finally, we evaluated the in vivo effects of the drug; BIIB021 inhibited the growth of EBV-positive NK cell lymphomas in a murine xenograft model. These results suggest that BIIB021 has suppressive effects against T and NK lymphoma cells through the induction of apoptosis or a cell cycle arrest. Moreover, BIIB021 might help to suppress EBV-positive T or NK cell lymphomas via the down-regulation of LMP1 expression.

Modeling EBV infection and pathogenesis in new-generation humanized mice

The development of highly immunodeficient mouse strains has allowed the reconstitution of functional human immune system components in mice. New-generation humanized mice generated in this manner have been extensively used for modeling viral infections that are exclusively human tropic. Epstein–Barr virus (EBV)-infected humanized mice reproduce cardinal features of EBV-associated B-cell lymphoproliferative disease and EBV-associated hemophagocytic lymphohistiocytosis (HLH). Erosive arthritis morphologically resembling rheumatoid arthritis (RA) has also been recapitulated in these mice. Low-dose EBV infection of humanized mice results in asymptomatic, persistent infection. Innate immune responses involving natural killer cells, EBV-specific adaptive T-cell responses restricted by human major histocompatibility and EBV-specific antibody responses are also elicited in humanized mice. EBV-associated T-/natural killer cell lymphoproliferative disease, by contrast, can be reproduced in a distinct mouse xenograft model. In this review, recent findings on the recapitulation of human EBV infection and pathogenesis in these mouse models, as well as their application to preclinical studies of experimental anti-EBV therapies, are described.