NKG2C copy number variations in five distinct populations in mainland China and susceptibility to nasopharyngeal carcinoma (NPC)

The Role of Natural Killer Cells in the Tumor Immune Microenvironment of EBV-Associated Nasopharyngeal Carcinoma

Endemic nasopharyngeal carcinoma (NPC) is closely associated with the Epstein-Barr virus (EBV), which contributes to tumor development and influences the tumor immune microenvironment (TIME) in NPC. Natural killer (NK) cells, as part of the innate immune system, play a crucial role in responding to viral infections and malignant cell transformations. Notably, NK cells possess a unique ability to target tumor cells independent of major histocompatibility complex class I (MHC I) expression. This means that MHC I-deficient tumor cells, which can escape from effective T cell attack, are susceptible to NK-cell-mediated killing. The activation of NK cells is determined by the signals generated through inhibitory and activating receptors expressed on their surface. Understanding the role of NK cells in the complex TIME of EBV+ NPC is of utmost importance. In this review, we provide a comprehensive summary of the current understanding of NK cells in NPC, focusing on their subpopulations, interactions, and cytotoxicity within the TIME. Moreover, we discuss the potential translational therapeutic applications of NK cells in NPC. This review aims to enhance our knowledge of the role of NK cells in NPC and provide valuable insights for future investigations.

Activating NKG2C Receptor: Functional Characteristics and Current Strategies in Clinical Applications

The interest in NK cells and their cytotoxic activity against tumour, infected or transformed cells continuously increases as they become a new efficient and off-the-shelf agents in immunotherapies. Their actions are balanced by a wide set of activating and inhibitory receptors, recognizing their complementary ligands on target cells. One of the most studied receptors is the activating CD94/NKG2C molecule, which is a member of the C-type lectin-like family. This review is intended to summarise latest research findings on the clinical relevance of NKG2C receptor and to examine its contribution to current and potential therapeutic strategies. It outlines functional characteristics and molecular features of CD94/NKG2C, its interactions with HLA-E molecule and presented antigens, pointing out a key role of this receptor in immunosurveillance, especially in the human cytomegalovirus infection. Additionally, the authors attempt to shed some light on receptor's unique interaction with its ligand which is shared with another receptor (CD94/NKG2A) with rather opposite properties.

Circular RNA CDR1as sponges miR-7-5p to enhance E2F3 stability and promote the growth of nasopharyngeal carcinoma

Background

Circular RNA (circRNA) CDR1as plays an important role in the occurrence and development of human tumors. The purpose of this study is to investigate the molecular mechanism of circRNA CDR1as in the development of nasopharyngeal carcinoma (NPC).

Methods

The mRNA expressions of circRNA CDR1as, miR-7-5p, and E2F3 were detected by qRT-PCR. The effects of circRNA CDR1as, miR-7-5p, and E2F3 on NPC cells were investigated using cell counting kit-8 (CCK8) method, colony formation assay, and representative metabolite assay. The molecular mechanism of circRNA CDR1 in NPC was studied by bioinformatics and luciferase reporter assay. In addition, the biological activity of circRNA CDR1as was also investigated in NPC xenograft tumor mice model.

Results

The results showed that the circRNA CDR1as expression was significantly up-regulated in NPC tissues by comparison with non-tumor NPE tissues (p < 0.01), suggesting that circRNA CDR1as was associated with poor prognosis in NPC patients. Moreover, circRNA CDR1as could up-regulate E2F3 expression by binding miR-7-5p, and promote the growth and glucose metabolism of NPC cells. Meanwhile, circRNA CDR1as could promote NPC progression through the negative regulation of miR-7-5p in the xenograft tumor model.

Conclusion

CircRNA CDR1as promoted the occurrence and development of NPCs by successively up-regulating the expression of miR-7-5p and E2F3, suggesting CircRNA CDR1as as a potential target for the treatment of NPC patients.

Trial registration The study was approved by the cancer center’s institutional research ethics committee on Oct 18, 2008 (2008GZ2847462)

Follistatin-Like Protein-1 Upregulates Dendritic Cell-Based Immunity in Patients with Nasopharyngeal Carcinoma

Follistatin-like protein-1 (FSTL1) is an inflammatory factor that can induce an inflammatory response and is expressed in cancers. However, little is known about its content and function in nasopharyngeal carcinoma (NPC). Interleukin (IL)-12 and IL-4 are primarily secreted by dendritic cells (DCs) and activated T lymphocytes, respectively; these factors can induce Th cell differentiation and cytotoxic lymphocyte production, both of which facilitate tumors through the STAT4 and STAT6 pathways, respectively. In this study, the relationship between FSTL1 and both IL-12 and IL-4 as well as the functional mechanism of these cytokines was explored. Enzyme-linked immunosorbent assay, flow cytometry, and Western blotting were used to assess the levels of key inflammatory factors and DC markers as well as elucidate the mechanism by which FSTL-1 mediates and exerts it antitumor effects. The results revealed that serum FSTL1 and IL-12 levels were significantly decreased in NPC patients compared with those in the control group (P < 0.05); conversely, IL-4 levels were increased (P < 0.05). Supernatants from the experimental groups (EGs) contained higher IL-4 and IL-12 levels than those from the control groups (P < 0.05). Additionally, phosphorylated-STAT6 and phosphorylated-STAT4 were increased in the EGs (P < 0.05). These results suggest that DC-mediated immunity was activated by FSTL1, which leads to an increase of IL-12 and IL-4 production and consequently activates the STAT4 and STAT6 pathways through upregulation of STAT4 and STAT6 phosphorylation, respectively.

NKG2C+NKG2A- Natural Killer Cells are Associated with a Lower Viral Set Point and may Predict Disease Progression in Individuals with Primary HIV Infection

Natural killer (NK) cells are the first line of defense against pathogens of the immune system and also play an important role in resistance against HIV. The activating receptor NKG2C and the inhibitory receptor NKG2A co-modulate the function of NK cells by recognizing the same ligand, HLA-E. However, the role of NKG2A and NKG2C on viral set point and the prediction of HIV disease progression have been rarely reported. In this study, we determined the expression of NKG2C or NKG2A on the surface of NK cells from 22 individuals with primary HIV infection (PHI) stage and 23 HIV-negative normal control (NC) subjects. The CD4⁺ T cell count and plasma level of HIV RNA in the infected individuals were longitudinally followed-up for about 720 days. The proportion of NKG2C⁺NKG2A^- NK cells was higher in subjects from the low set point group and was negatively correlated with the viral load. In addition, strong anti-HIV activities were observed in NKG2C⁺ NK cells from the HIV-positive donors. Furthermore, a proportion of NKG2C⁺NKG2A^- NK cells >35.45%, and a ratio of NKG2C/NKG2A >1.7 were predictive for higher CD4⁺ T cell counts 720 days after infection. Collectively, the experimental results allow us to draw the conclusion that NKG2C⁺ NK cells might exert an antiviral effect and that the proportion of NKG2C⁺NKG2A^- NK cells, and the ratio of NKG2C/NKG2A, are potential biomarkers for predicting HIV disease progression.

Follistatin-like protein 1 contributes to dendritic cell and T-lymphocyte activation in nasopharyngeal carcinoma patients by altering nuclear factor κb and Jun N-terminal kinase expression

Follistatin‐like protein 1 (FSTL1) is a newly characterized protein that can regulate the immune response in various ways. Dendritic cells (DCs) are central to immune regulation. In this study, we explored the impact of FSTL1 on DC activity in nasopharyngeal carcinoma (NPC) patients. The surface expression of CD40, CD86, and HLA‐DR on DCs was analyzed and showed significantly elevated expression levels, indicating DC maturity. After FSTL1 was added to DCs collected from NPC patients (n = 50), controls (n = 47), and healthy donors (n = 10), interferon γ secretion and T‐cell receptor expression in cytotoxic T lymphocytes were also investigated. In the experimental groups, the expression of the critical immune protein nuclear factor (NF)‐κb was upregulated, whereas Jun N‐terminal kinase (JNK) was downregulated. Our findings demonstrate that FSTL1 plays a critical role in immune regulation, enhancing the antigen presentation ability of DCs by up‐regulating NF‐κb expression and down‐regulating JNK expression.

Differential frequency of NKG2C/KLRC2 deletion in distinct African populations and susceptibility to Trachoma: a new method for imputation of KLRC2 genotypes from SNP genotyping data

NKG2C is an activating receptor that is preferentially expressed on natural killer (NK) cells. The gene encoding NKG2C (killer cell lectin-like receptor C2, KLRC2) is present at different copy numbers in the genomes of different individuals. Deletion at the NKG2C locus was investigated in a case-control study of 1522 individuals indigenous to East- and West-Africa and the association with the ocular Chlamydia trachomatis infection and its sequelae was explored. The frequency of homozygous KLRC2 deletion was 13.7 % in Gambians and 4.7 % in Tanzanians. A significantly higher frequency of the deletion allele was found in West-Africans from the Gambia and Guinea-Bissau (36.2 % p = 2.105 × 10(-8), 26.8 % p = 0.050; respectively) in comparison to East-African Tanzanians where the frequency of the deletion is comparable to other human populations (20.9 %). We found no evidence for an association between the numbers of KLRC2 gene copies and the clinical manifestations of trachoma (follicular trachoma or conjunctival scarring). A new method for imputation of KLRC2 genotypes from single nucleotide polymorphism (SNP) data in 2621 individuals from the Gambia further confirmed these results. Our data suggest that NKG2C does not play a major role in trachomatous disease. We found that the deletion allele is present at different frequencies in different populations but the reason behind these differences is currently not understood. The new method offers the potential to use SNP arrays from genome wide association studies to study the frequency of KLRC2 deletion in other populations and its association with other diseases.