ERK/c-Jun Recruits Tet1 to Induce Zta Expression and Epstein-Barr Virus Reactivation through DNA Demethylation

Jun/Fos promotes migration and invasion of hepatocellular carcinoma cells by enhancing BORIS promoter activity

The Brother of the Regulator of Imprinted Sites (BORIS), as a specific indicator of hepatocellular carcinoma, exhibits a significant increase in expression. However, its upstream regulatory network remains enigmatic. Previous research has indicated a strong correlation between the Hippo pathway and the progression of hepatocellular carcinoma. It is well established that the Activator Protein-1 (AP-1) frequently engages in interactions with the Hippo pathway. Thus, we attempt to prove whether Jun and Fos, a major member of the AP-1 family, are involved in the regulation of BORIS expression. Bioinformatics analysis revealed the existence of binding sites for Jun and Fos within the BORIS promoter. Through a series of overexpression and knockdown experiments, we corroborated that Jun and Fos have the capacity to augment BORIS expression, thereby fostering the migration and invasion of hepatocellular carcinoma cells. Moreover, Methylation-Specific PCR and Bisulfite Sequencing PCR assays revealed that Jun and Fos do not have a significant impact on the demethylation of the BORIS promoter. However, luciferase reporter and chromatin immunoprecipitation experiments substantiated that Jun and Fos could directly bind to the BORIS promoter, thereby enhancing its transcription. In conclusion, these results suggest that Jun and Fos can promote the development of hepatocellular carcinoma by directly regulating the expression of BORIS. These findings may provide experimental evidence positioning BORIS as a novel target for the clinical intervention of hepatocellular carcinoma.

Targeting the crosstalk of epigenetic modifications and immune evasion in nasopharyngeal cancer

Nasopharyngeal carcinoma (NPC) is a distinct type of head and neck cancer that is highly associated with Epstein-Barr virus (EBV) infection. EBV acts as an epigenetic driver in NPC tumorigenesis, reprogramming the viral and host epigenomes to regulate viral latent gene expression, and creating an environment conducive to the malignant transformation of nasopharyngeal epithelial cells. Targeting epigenetic mechanisms in pre-clinical studies has been shown promise in eradicating tumours and overcoming immune resistance in some solid tumours. However, its efficacy in NPC remains inclusive due to the complex nature of this cancer. In this review, we provide an updated understanding of the roles of epigenetic factors in regulating EBV latent gene expression and promoting NPC progression. We also explore the crosstalk between epigenetic mechanisms and immune evasion in NPC. Particularly, we discuss the potential roles of DNA methyltransferase (DNMT) and histone deacetylase (HDAC) inhibitors in reversing immune suppression and augmenting antitumour immunity. Furthermore, we highlight the advantages of combining epigenetic therapy and immune checkpoint inhibitor to reverse immune resistance and improve clinical outcomes. Epigenetic drugs have the potential to modulate both epigenetic mediators and immune factors involved in NPC. However, further research is needed to fully comprehend the diverse range of epigenetic modifications in NPC. A deeper understanding of the crosstalk between epigenetic mechanisms and immune evasion during NPC progression is crucial for the development of more effective treatments for this challenging disease.

In Memory of the Virologist Jianguo Wu, 1957-2022

It is with deep sorrow that we mourn the passing of the virologist Professor Jianguo Wu [...].

Comprehensive insight into altered host cell-signaling cascades upon Helicobacter pylori and Epstein-Barr virus infections in cancer

Cancer is characterized by mutagenic events that lead to disrupted cell signaling and cellular functions. It is one of the leading causes of death worldwide. Literature suggests that pathogens, mainly Helicobacter pylori and Epstein-Barr virus (EBV), have been associated with the etiology of human cancer. Notably, their co-infection may lead to gastric cancer. Pathogen-mediated DNA damage could be the first and crucial step in the carcinogenesis process that modulates numerous cellular signaling pathways. Altogether, it dysregulates the metabolic pathways linked with cell growth, apoptosis, and DNA repair. Modulation in these pathways leads to abnormal growth and proliferation. Several signaling pathways such RTK, RAS/MAPK, PI3K/Akt, NFκB, JAK/STAT, HIF1α, and Wnt/β-catenin are known to be altered in cancer. Therefore, this review focuses on the oncogenic roles of H. pylori, EBV, and its associated signaling cascades in various cancers. Scrutinizing these signaling pathways is crucial and may provide new insights and targets for preventing and treating H. pylori and EBV-associated cancers.

EpsteinBarr virusencoded microRNAs involve in tumorigenesis and development

Epstein-Barr virus (EBV), a definite tumorigenic virus, is closely related to the development of nasopharyngeal cancer, gastric cancer, lymphoma and other tumors. EBV encodes a total of 44 mature microRNAs, which can regulate the expression of virus and host genes. EBV-encoded microRNAs and their regulated target molecules participate in the biological functions of tumor apoptosis, proliferation, invasion, and metastasis during tumorigenesis and development, and play an important role in the development of tumor.

Coiled-coil domain-containing 80 accelerates atherosclerosis development through decreasing lipoprotein lipase expression via ERK1/2 phosphorylation and TET2 expression

Recent studies showed that coiled-coil domain-containing 80 (CCDC80) has a positive link with atherosclerosis and that plasma CCDC80 levels are positively correlated with the levels of fasting plasma triglycerides (TG) in obese individuals. The underlying mechanisms, however, are unclear. Using Hematoxylin-eosin (H&E) and Oil Red O staining, we found that CCDC80 overexpression in vivo significantly increased plasma lipid contents, decreased the expression and activity of lipoprotein lipase (LPL), and accelerated the development of atherosclerosis. Conversely, knockdown of CCDC80 decreased plaque lesions area. In vitro, qRT-PCR and western blot results showed that CCDC80 overexpression significantly decreased, while CCDC80 knockdown increased, LPL expression in cultured vascular smooth muscle cells (VSMCs). Further, we found that CCDC80 reduced LPL expression via inhibiting the phosphorylation of extracellular regulated protein kinase 1/2 (ERK1/2) and also increased the methylation of LPL promoter via down-regulating Tet methylcytosine dioxygenase 2 (TET2). Our results also revealed that CCDC80 significantly down-regulated TET2 expression through decreasing the phosphorylation of ERK1/2. In addition, we found that CCDC80 decreased binding of TET2 to forkhead box O3 (FOXO3a) but had no effect on FOXO3a expression. On the other hand, and that FOXO3a was partially involved in TET2-regulated LPL expression. CCDC80 down-regulated ERK1/2 phosphorylation and decreased expression of TET2 and its interaction with FOXO3a, leading to a reduction of LPL expression and acceleration of atherosclerosis.

Epstein-Barr virus infection and nasopharyngeal carcinoma

Epstein-Barr virus (EBV) is associated with multiple types of human cancer, including lymphoid and epithelial cancers. The closest association with EBV infection is seen in undifferentiated nasopharyngeal carcinoma (NPC), which is endemic in the southern Chinese population. A strong association between NPC risk and the HLA locus at chromosome 6p has been identified, indicating a link between the presentation of EBV antigens to host immune cells and NPC risk. EBV infection in NPC is clonal in origin, strongly suggesting that NPC develops from the clonal expansion of a single EBV-infected cell. In epithelial cells, the default program of EBV infection is lytic replication. However, latent infection is the predominant mode of EBV infection in NPC. The establishment of latent EBV infection in pre-invasive nasopharyngeal epithelium is believed to be an early stage of NPC pathogenesis. Recent genomic study of NPC has identified multiple somatic mutations in the upstream negative regulators of NF-κB signalling. Dysregulated NF-κB signalling may contribute to the establishment of latent EBV infection in NPC. Stable EBV infection and the expression of latent EBV genes are postulated to drive the transformation of pre-invasive nasopharyngeal epithelial cells to cancer cells through multiple pathways.This article is part of the themed issue 'Human oncogenic viruses'.

c-Jun integrates signals from both MEK/ERK and MKK/JNK pathways upon vaccinia virus infection

Usurpation of the host's signalling pathways is a common strategy employed by viruses to promote their successful replication. Here we show that infection with the orthopoxvirus vaccinia virus (VACV) leads to sustained stimulation of c-Jun activity during the entire infective cycle. This stimulation is temporally regulated through MEK/ERK or MKK/JNK pathways, i.e. during the early/mid phase (1 to 6 hpi) and in the late phase (9 to 24 hpi) of the infective cycle, respectively. As a transcriptional regulator, upon infection with VACV, c-Jun is translocated from the cytoplasm to the nucleus, where it binds to the AP-1 DNA sequence found at the promoter region of its target genes. To investigate the role played by c-Jun during VACV replication cycle, we generated cell lines that stably express a c-Jun-dominant negative (DNc-Jun) mutation. Our data revealed that c-Jun is required during early infection to assist with viral DNA replication, as demonstrated by the decreased amount of viral DNA found in the DNc-Jun cells. We also demonstrated that c-Jun regulates the expression of the early growth response gene (egr-1), a gene previously shown to affect VACV replication mediated by MEK/ERK signalling. VACV-induced stimulation of the MKK/JNK/JUN pathway impacts viral dissemination, as we observed a significant reduction in both viral yield, during late stages of infection, and virus plaque size. Collectively, our data suggest that, by modulating the host's signalling pathways through a common target such as c-Jun, VACV temporally regulates its infective cycle in order to successfully replicate and subsequently spread.

MUC1 inhibition leads to decrease in PD-L1 levels via upregulation of miRNAs

The PD-L1/PD-1 pathway is a critical component of the immunosuppressive tumor microenvironment in acute myeloid leukemia (AML), but little is known about its regulation. We investigated the role of the MUC1 oncoprotein in modulating PD-L1 expression in AML. Silencing of MUC1 in AML cell lines suppressed PD-L1 expression without a decrease in PD-L1 mRNA levels, suggesting a post-transcriptional mechanism of regulation. We identified the microRNAs miR-200c and miR-34a as key regulators of PD-L1 expression in AML. Silencing of MUC1 in AML cells led to a marked increase in miR-200c and miR-34a levels, without changes in precursor microRNA, suggesting that MUC1 might regulate microRNA-processing. MUC1 signaling decreased the expression of the microRNA-processing protein DICER, via the suppression of c-Jun activity. NanoString (Seattle, WA, USA) array of MUC1-silenced AML cells demonstrated an increase in the majority of probed microRNAs. In an immunocompetent murine AML model, targeting of MUC1 led to a significant increase in leukemia-specific T cells. In concert, targeting MUC1 signaling in human AML cells resulted in enhanced sensitivity to T-cell-mediated lysis. These findings suggest MUC1 is a critical regulator of PD-L1 expression via its effects on microRNA levels and represents a potential therapeutic target to enhance anti-tumor immunity.