Epstein-Barr virus latent membrane protein 1 induces CD69 expression through activation of nuclear factor-κB

BSRF1 modulates IFN-β-mediated antiviral responses by inhibiting NF-κB activity via an IKK-dependent mechanism in Epstein-Barr virus infection

The Epstein-Barr virus (EBV) encoded tegument protein BSRF1 plays a significant role in the processes of viral maturation and release, however, it's not clear whether BSRF1 is involved in the modulation of host innate immunity. In this study, we demonstrated that BSRF1 can inhibit interferon β (IFN-β) production by downregulating nuclear factor kappa B (NF-κB) activity and subsequently reducing the yield of inflammatory cytokines, thereby facilitating viral replication. Dual luciferase reporter assays indicated that BSRF1 may inhibit NF-κB signaling at the level of IKK or between IKK and p65, while co-immunoprecipitation experiments revealed its association with multiple critical host adaptor proteins. Mechanistically, BSRF1 hinders the phosphorylation of IκBα at Ser32/36 and K48-linked polyubiquitination, thereby preventing proteasome-mediated degradation of IκBα by disrupting the assembly of the regulatory subunits within the IKK complex. Although BSRF1 interacts with p65 and its N-terminal domain, it does not alter the formation of the p65/p50 heterodimer. Instead, it prevents the nuclear translocation of p65 by inhibiting the dissociation of IκBα from the NF-κB dimer. Collectively, these findings suggested that BSRF1 assists EBV's evasion of host innate immune system by inhibiting the antiviral response to IFN-β through the NF-κB signaling pathway, potentially contributing to the virus's ability to establish persistent infection and its association with tumorigenesis.

B cell activation and proliferation increase intracellular zinc levels

Zinc ions serve as second messengers in major cellular pathways, including the regulation pathways of proliferation and their proper regulation is necessary for homeostasis and a healthy organism. Accordingly, expression of zinc transporters can be altered in various cancer cell lines and is often involved in producing elevated intracellular zinc levels. In this study, human B cells were infected with Epstein–Barr virus (EBV) to generate immortalized cells, which revealed traits of tumor cells, such as high proliferation rates and an extended lifespan. These cells showed differentially altered zinc transporter expression with ZIP7 RNA and protein expression being especially increased as well as a corresponding increased phosphorylation of ZIP7 in EBV-transformed B cells. Accordingly, free zinc levels were elevated within these cells. To prove whether the observed changes resulted from immortalization or rather high proliferation, free zinc levels in in vitro activated B cells and in freshly isolated B cells expressing the activation marker CD69 were determined. Here, comparatively increased zinc levels were found, suggesting that activation and proliferation, but not immortalization, act as crucial factors for the elevation of intracellular free zinc.

CD69 partially inhibits apoptosis and erythroid differentiation via CD24, and their knockdown increase imatinib sensitivity in BCR-ABL-positive cells

Chronic myeloid leukemia (CML) is caused by a constitutively active BCR-ABL tyrosine kinase. Tyrosine kinase inhibitors (TKIs) imatinib and its derivatives represent a breakthrough for CML therapy, but the use of TKI alone is ineffective for many CML patients. CD69, an early activation marker of lymphocytes, participates in immune and inflammatory responses. Previous studies revealed that BCR-ABL upregulates CD69 expression; however, the role of CD69 in CML cells is unknown. Here, we demonstrate that BCR-ABL induced CD69 promoter activity and mRNA and protein expression via the NF-κB pathway. CD69 knockdown partially increased apoptosis and expression of erythroid differentiation markers, α-globin, ζ-globin, and glycophorin A, and increased imatinib sensitivity in K562 and KU812 CML cells. Gene microarray analysis and quantitative real-time PCR verified that CD24, an oncogenic gene, downregulated in K562 cells upon CD69 knockdown. CD69 overexpression increased, whereas CD69 knockdown inhibited CD24 promoter activity and mRNA and protein levels. CD24 knockdown also partially increased apoptosis, erythroid differentiation, and imatinib sensitivity in K562 cells, whereas its overexpression inhibited the effects of CD69 knockdown on apoptosis, erythroid differentiation, and imatinib sensitivity in K562 cells. Imatinib-induced apoptosis and erythroid differentiation were also inhibited by CD69 or CD24 overexpression in BCR-ABL-expressing CML cell lines and CD34⁺ cells. Taken together, CD24 is a downstream effector of CD69. CD69 and CD24 partially inhibit apoptosis and erythroid differentiation in CML cells; thus, they may be potential targets to increase imatinib sensitivity.

NF-κB signaling pathway and its potential as a target for therapy in lymphoid neoplasms

The NF-κB pathway, a critical regulator of apoptosis, plays a key role in many normal cellular functions. Genetic alterations and other mechanisms leading to constitutive activation of the NF-κB pathway contribute to cancer development, progression and therapy resistance by activation of downstream anti-apoptotic pathways, unfavorable microenvironment interactions, and gene dysregulation. Not surprisingly, given its importance to normal and cancer cell function, the NF-κB pathway has emerged as a target for therapy. In the review, we present the physiologic role of the NF-κB pathway and recent advances in better understanding of the pathologic roles of the NF-κB pathway in major types of lymphoid neoplasms. We also provide an update of clinical trials that use NF-κB pathway inhibitors. These trials are exploring the clinical efficiency of combining NF-κB pathway inhibitors with various agents that target diverse mechanisms of action with the goal being to optimize novel therapeutic opportunities for targeting oncogenic pathways to eradicate cancer cells.

Impact of methimazole treatment on magnesium concentration and lymphocytes activation in adolescents with Graves' disease

The aim of this research was to assess plasma magnesium (Mg) concentration, the frequencies of activated T CD4+ and T CD8+ lymphocytes and B lymphocytes in adolescents with hyperthyroidism due to Graves' disease (GD), and to assess changes in the above-mentioned parameters during methimazole (MMI) treatment. The frequencies of activated T and B cells were measured by flow cytometry method and plasma Mg concentration was determined by spectrophotometry method in 60 adolescents at the time of GD diagnosis and after receiving the normalisation of the thyroid hormones levels. The control group consisted of 20 healthy volunteers. We observed lower plasma Mg concentration, and higher frequencies of activated T and B lymphocytes in the study group before the treatment in comparison with healthy controls, and with study group in MMI-induced euthyreosis (p < 0.01).Statistically significant negative correlations between the percentages of activated T CD3+, T CD4+, T CD8+ and B CD19+ lymphocytes, and plasma Mg concentration before the treatment were found (r < -0.335, p < 0.002). After the treatment no vital differences in plasma Mg concentration, and in percentages of activated cells between GD patients and controls were found, except CD8+CD25+ cells (p = 0.03). The present study demonstrates that both activated T and B cells might play an important role in the pathogenesis of GD, and activation is related to Mg plasma level. The use of MMI in treatment of hyperthyroidism due to GD leads to decrease the frequencies of activated lymphocytes and normalisation of Mg levels.