Baicalein inhibits growth of Epstein-Barr virus-positive nasopharyngeal carcinoma by repressing the activity of EBNA1 Q-promoter

In-silico evaluation of Oroxylum indicum vent compounds in the plausible treatment and prevention of nasopharyngeal cancer

BACKGROUND

Shyonaka (Oroxylum indicum Vent) is widely used in Ayurveda and in ethnomedical practice for the treatment of inflammation, pain, diarrhea, non-healing ulcers, and cancer. Owing to the high prevalence of Epstein-Barr virus (EBV) infection in Nasopharyngeal carcinoma (NPC) patients, simultaneous targeting of proteins involved in both EBV replication and NPC proliferation might help to manage the disease effectively.

OBJECTIVES

This study is designed to identify potential dual targeting inhibitors from Oroxylum indicum having the potential to inhibit both EBV and NPC. This study also attempted quantitative analysis of Shyonaka Bark Decoction (SBD) to confirm the presence of Baicalein and Chrysin which are predominant marker compounds of Shyonaka.

METHODOLOGY

The HPLC analysis of stem bark and root bark of Oroxylum indicum was done to estimate the presence of marker compounds Baicalein and Chrysalin. The in-silico analysis included ADMET analysis followed by molecular docking of known compounds from Oroxylum indicum (retrieved from IMPPAT database) onto the target proteins of EBV (BHRF1, NEC1, dUTPase, Uracil DNA glycosylase) and NPC (COX-2, EGFR, and MDM2) using DOCK6 tool. Further validations were done using the molecular dynamics simulations of top screened molecules onto the selected target proteins using AMBER20 package and their corresponding MMGBSA binding free-energy values were calculated.

RESULTS

The molecular docking revealed that the key molecules from the plant, scutellarein 7-rutinoside (S7R), scutellarin (SCU) and 6-hydroxyluteolin, Baicalein and 5,7-Dihydroxy-2-phenyl-6-[3,4,5-trihydroxy-6-(hydroxymethyl)oxan-2-yl]oxychromen-4-one (57D) are effectively intervening with the target proteins of EBV, one of the key causative factors of NPC and the NPC specific targets which have the potential to reduce tumor size and other consequences of NPC. The molecular dynamics simulations of S7R, Baicalein and 57D, Baicalein with MDM-2 protein and dUTPase protein, respectively, showed stable interactions between them which were further assessed by the binding energy calculations.

CONCLUSION

Overall, the in-silico evaluation of these phytochemicals with target proteins indicates their potential to inhibit both EBV and NPC which needs further in-vitro and in-vivo validations.

Baicalein targets STMN1 to inhibit the progression of nasopharyngeal carcinoma via regulating the Wnt/β-catenin pathway

BACKGROUNDS

Nasopharyngeal carcinoma is a common malignancy in the head and neck. Baicalein has been reported to exert the anticancer effects on various cancers. In this study, our aim was to explore the function of baicalein in the development of nasopharyngeal carcinoma and further investigate the potential underlying mechanisms.

METHODS

Cell Counting Kit (CCK)-8 assay, EdU assay, sphere formation assay, flow cytometry, and transwell invasion assay were conducted to determine cell proliferation, stemness, apoptosis, and invasion, respectively. Western blot was performed to examine the protein levels of PCNA, MMP9, STMN1, β-catenin, and Wnt3A. The mRNA level of STMN1 was assessed using real-time quantitative polymerase chain reaction (RT-qPCR). Xenograft tumor model was carried out to evaluate the effects of baicalein on tumor growth in vivo. Immunohistochemistry (IHC) assay was used to detect the levels of PCNA, MMP9, and STMN1 in tumor tissues from mice.

RESULTS

Baicalein significantly induced cell apoptosis and impeded cell proliferation, invasion, and stemness of nasopharyngeal carcinoma cells. STMN1 was highly expressed in nasopharyngeal carcinoma, and baicalein could directly downregulate STMN1 expression. STMN1 knockdown hampered the progression of nasopharyngeal carcinoma cells. Moreover, the effects of baicalein on cell proliferation, stemness, invasion, and apoptosis in nasopharyngeal carcinoma cells were harbored by STMN1 overexpression. Baicalein regulated STMN1 to inhibit the activation of the Wnt/β-catenin pathway. SKL2001, an agonist of the Wnt/β-catenin pathway, could reverse the effects of STMN1 knockdown on the progression of nasopharyngeal carcinoma. In addition, baicalein markedly impeded tumor growth in vivo.

CONCLUSION

Baicalein regulated the STMN1/Wnt/β-catenin pathway to restrain the development of nasopharyngeal carcinoma.

Update of Natural Products and Their Derivatives Targeting Epstein-Barr Infection

Epstein-Barr (EBV) is a human γ-herpesvirus that undergoes both a productive (lytic) cycle and a non-productive (latent) phase. The virus establishes enduring latent infection in B lymphocytes and productive infection in the oral mucosal epithelium. Like other herpesviruses, EBV expresses its genes in a coordinated pattern during acute infection. Unlike others, it replicates its DNA during latency to maintain the viral genome in an expanding pool of B lymphocytes, which are stimulated to divide upon infection. The reactivation from the latent state is associated with a productive gene expression pattern mediated by virus-encoded transcriptional activators BZLF-1 and BRLF-1. EBV is a highly transforming virus that contributes to the development of human lymphomas. Though viral vectors and mRNA platforms have been used to develop an EBV prophylactic vaccine, currently, there are no vaccines or antiviral drugs for the prophylaxis or treatment of EBV infection and EBV-associated cancers. Natural products and bioactive compounds are widely studied for their antiviral potential and capability to modulate intracellular signaling pathways. This review was intended to collect information on plant-derived products showing their antiviral activity against EBV and evaluate their feasibility as an alternative or adjuvant therapy against EBV infections and correlated oncogenesis in humans.

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.

Promising Role of the Scutellaria baicalensis Root Hydroxyflavone-Baicalein in the Prevention and Treatment of Human Diseases

Plant roots, due to a high content of natural antioxidants for many years, have been used in herbal medicine. It has been documented that the extract of Baikal skullcap (Scutellaria baicalensis) has hepatoprotective, calming, antiallergic, and anti-inflammatory properties. Flavonoid compounds found in the extract, including baicalein, have strong antiradical activity, which improves overall health and increases feelings of well-being. Plant-derived bioactive compounds with antioxidant activity have for a long time been used as an alternative source of medicines to treat oxidative stress-related diseases. In this review, we summarized the latest reports on one of the most important aglycones with respect to the pharmacological activity and high content in Baikal skullcap, which is 5,6,7-trihydroxyflavone (baicalein).

Fighting Carcinogenesis with Plant Metabolites by Weakening Proliferative Signaling and Disabling Replicative Immortality Networks of Rapidly Dividing and Invading Cancerous Cells

BACKGROUND

Cancer, an uncontrolled multistage disease causing swift division of cells, is a leading disease with the highest mortality rate. Cellular heterogeneity, evading growth suppressors, resisting cell death, and replicative immortality drive the tumor progression by resisting the therapeutic action of existing anticancer drugs through a series of intrinsic and extrinsic cellular interactions. The innate cellular mechanisms also regulate the replication process as a fence against proliferative signaling, enabling replicative immortality through telomere dysfunction.

AREA COVERED

The conventional genotoxic drugs have several off-target and collateral side effects associated with them. Thus, the need for the therapies targeting cyclin-dependent kinases or P13K signaling pathway to expose cancer cells to immune destruction, deactivation of invasion and metastasis, and maintaining cellular energetics is imperative. Compounds with anticancer attributes isolated from plants and rich in alkaloids, terpenes, and polyphenols have proven to be less toxic and highly targetspecific, making them biologically significant. This has opened a gateway for the exploration of more novel plant molecules by signifying their role as anticancer agents in synergy and alone, making them more effective than the existing cytotoxic regimens.

EXPERT OPINION

In this context, the current review presented recent data on cancer cases around the globe, along with discussing the fundamentals of proliferative signaling and replicative immortality of cancer cells. Recent findings were also highlighted, including antiproliferative and antireplicative action of plant-derived compounds, besides explaining the need for improving drug delivery systems.

Molecular Mechanisms of Flavonoids against Tumor Gamma-Herpesviruses and Their Correlated Cancers-A Focus on EBV and KSHV Life Cycles and Carcinogenesis

Epstein-Barr virus (EBV) and Kaposi sarcoma-associated herpesvirus (KSHV) are cancer-causing viruses that belong to human gamma-herpesviruses. They are DNA viruses known to establish lifelong infections in humans, with the ability to develop various types of cancer. Drug resistance remains the main barrier to achieving effective therapies for viral infections and cancer. Thus, new medications with dual antiviral and anticancer actions are highly needed. Flavonoids are secondary metabolites biosynthesized by plants with diverse therapeutic effects on human health. In this review, we feature the potential role of flavonoids (flavones, protoflavones, isoflavones, flavanones, flavonols, dihydroflavonols, catechins, chalcones, anthocyanins, and other flavonoid-type compounds) in controlling gamma-herpesvirus-associated cancers by blocking EBV and KSHV infections and inhibiting the formation and growth of the correlated tumors, such as nasopharyngeal carcinoma, Burkitt's lymphoma, gastric cancer, extranodal NK/T-cell lymphoma, squamous cell carcinoma, Kaposi sarcoma, and primary effusion lymphoma. The underlying mechanisms via targeting EBV and KSHV life cycles and carcinogenesis are highlighted. Moreover, the effective concentrations or doses are emphasized.

Baicalein Inhibits Metastatic Phenotypes in Nasopharyngeal Carcinoma Cells via a Focal Adhesion Protein Integrin β8

Baicalein, a prominent flavonoid from the indigenous herbal plant Scutellaria baicalensis Georgi, possesses broad-spectrum anticancer activities. However, the biological effects of baicalein on nasopharyngeal carcinoma (NPC) and its underlying mechanisms remain unclarified. Thus, in this study, we examined the effects of baicalein on NPC cell lines and investigated the corresponding molecular mechanism through transcriptome profiling. In the study, four NPC cell lines were treated with various concentrations of baicalein at different time points. Cellular toxicity and proliferative inhibition of baicalein were examined by MTT assay. Metastatic phenotypes of NPC cells were investigated by wound healing, transwell, and adhesion assays. Additionally, microarray experiments were performed to determine the cellular pathways affected by baicalein. The expression and localization of the integrin β8 were validated by western immunoblotting and immunofluorescence. Our results revealed that baicalein exhibited its cytotoxicity and antiproliferative activity on all tested NPC cell lines. It also significantly inhibited metastatic phenotypes at sub-lethal concentrations. Transcriptomic analysis showed that baicalein significantly affected the focal adhesion pathway in NPC, where integrin β8 was greatly diminished. Thus, the present study results suggested that baicalein inhibits the metastatic phenotypes of NPC cells by modulating integrin β8, one of the major molecules in a focal adhesion pathway.

Simultaneous Determination of Four Bioactive Flavonoids in Rat Plasma by UPLC-MS/MS and Comparative Pharmacokinetic Study after Oral Administration of Danyikangtai Powder and Three Compatibilities

Background:

Danyikangtai powder, a Traditional Chinese Medicine (TCM) formula, shows promise to become a novel drug candidate for the simultaneous treatment of chronic cholecystitis and chronic pancreatitis. However, the pharmacokinetic behavior of Danyikangtai powder remains unclear.

Objective:

We investigated the comparative pharmacokinetics of four flavonoids in rats after oral administration of Danyikangtai powder and three compatibilities.

Materials and Methods:

The comparative pharmacokinetics was studied by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC–MS/MS). Chromatographic separation was performed on a Universil XB-C18 column with a gradient mobile phase containing 0.1% (v/v) aqueous formic acid and acetonitrile. All analytes and internal standard were quantitated in the multiple reaction monitoring modes with a positive electrospray ionization interface.

Results and Discussion:

Danyikangtai powder and Scutellariae radix have similar pharmacokinetic behaviors in rats after oral administration. However, the elimination of four flavonoids in rats after oral administration of Danyikangtai powder was accelerated, which was possibly related to the reduction of the potential hepatotoxicity of Scutellariae radix. The varying degrees of change in pharmacokinetic parameters after oral administration of different herb combinations suggested that herb–herb interactions occurred in vivo.

Conclusions:

This study will be helpful to reveal the safety, rational and mechanism of Danyikangtai powder formula compatibility, thereby providing pre-clinical research data for its new drug development and guidance for its rational clinical application.

Broad Anti-Viral Capacities of Lian-Hua-Qing-Wen Capsule and Jin-Hua-Qing-Gan Granule and Rational use Against COVID-19 Based on Literature Mining

The novel coronavirus disease 2019 (COVID-19) has become a matter of international concern as the disease is spreading exponentially. Statistics showed that infected patients in China who received combined treatment of Traditional Chinese Medicine and modern medicine exhibited lower fatality rate and relatively better clinical outcomes. Both Lian-Hua-Qing-Wen Capsule (LHQWC) and Jin-Hua-Qing-Gan Granule (JHQGG) have been recommended by China Food and Drug Administration for the treatment of COVID-19 and have played a vital role in the prevention of a variety of viral infections. Here, we desired to analyze the broad-spectrum anti-viral capacities of LHQWC and JHQGG, and to compare their pharmacological functions for rational clinical applications. Based on literature mining, we found that both LHQWC and JHQGG were endowed with multiple antiviral activities by both targeting viral life cycle and regulating host immune responses and inflammation. In addition, from literature analyzed, JHQGG is more potent in modulating viral life cycle, whereas LHQWC exhibits better efficacies in regulating host anti-viral responses. When translating into clinical applications, oral administration of LHQWC could be more beneficial for patients with insufficient immune functions or for patients with alleviated symptoms after treatment with JHQGG.

Curcumin suppresses the proliferation of oral squamous cell carcinoma through a specificity protein 1/nuclear factor-κB-dependent pathway

Oral squamous cell carcinoma (OSCC) is the most common cancer of the oral cavity. Curcumin (Cur), a naturally derived compound, is reported to have broad-spectrum anticancer activity and is considered as an effective nuclear factor-κB (NF-κB) inhibitor. The present study aimed to clarify the detailed molecular mechanism though which Cur regulates NF-κB pathway activity in OSCC. The viability of HSC3 and CAL33 cells following treatment with Cur was determined using a Cell Counting Kit-8 assay. The protein and mRNA expression of specificity protein 1 (Sp1), p65 and heat shock factor 1 (HSF1) was determined by western blotting and reverse transcription-quantitative PCR analysis, respectively. The NF-κB activity was measured by Dual-Luciferase reporter assay. Short hairpin RNA targeting Sp1 or control RNA was transfected into HSC3 cells using X-treme GENE HP DNA Transfection System. Colony formation assays were performed using crystal violet staining. The results demonstrated that Cur significantly inhibited the viability and colony formation ability of HSC3 and CAL33 cells. In addition, Cur decreased the expression of Sp1, p65 and HSF1 by suppressing their transcription levels. Cur decreased NF-κB activity in OSCC cells, and Sp1 downregulation enhanced the effect of Cur. The findings from the present study suggested that Cur may inhibit the proliferation of OSCC cells via a Sp1/NF-κB-dependent mechanism.

Epstein-Barr Virus Early Protein BFRF1 Suppresses IFN-β Activity by Inhibiting the Activation of IRF3

Epstein-Barr virus (EBV) is the causative agent of infectious mononucleosis that is closely associated with several human malignant diseases, while type I interferon (IFN-I) plays an important role against EBV infection. As we all know, EBV can encode some proteins to inhibit the production of IFN-I, but it’s not clear whether other proteins also take part in this progress. EBV early lytic protein BFRF1 is shown to be involved in viral maturation, however, whether BFRF1 participates in the host innate immune response is still not well known. In this study, we found BFRF1 could down-regulate sendai virus-induced IFN-β promoter activity and mRNA expression of IFN-β and ISG54 during BFRF1 plasmid transfection and EBV lytic infection, but BFRF1 could not affect the promoter activity of NF-κB or IRF7. Specifically, BFRF1 could co-localize and interact with IKKi. Although BFRF1 did not interfere the interaction between IKKi and IRF3, it could block the kinase activity of IKKi, which finally inhibited the phosphorylation, dimerization, and nuclear translocation of IRF3. Taken together, BFRF1 may play a critical role in disrupting the host innate immunity by suppressing IFN-β activity during EBV lytic cycle.

Investigation on the Metabolism of Curcumin and Baicalein in Zebrafish by Liquid Chromatography-tandem Mass Spectrometry Analysis

Background:

Curcumin (CUR) and baicalein (BAI) are the main active ingredients in Curcuma longa and Scutellaria baicalensis, which are used together in Jiang-Qin-Si-Wu decoction to treat gynecological diseases. On the other hand, zebrafish, as a metabolic model has become more popular, therefore, the metabolism of CUR and BAI in zebrafish is investigated in the present study.

Methods:

Zebrafish embryos after hatching 48 hours were divided into four experimental groups. The blank group was exposed to 1 mL of ultra-pure water. Three drug-treated groups were exposed to CUR (8 μM, 1 mL), BAI (8 μM, 1 mL), CUR and BAI (8 μM, 2 mL), respectively. After homogenization, they were analyzed by liquid chromatography-tandem mass spectrometry (LCMS/ MS). The structure of the metabolites was determined by comparing their corresponding mass spectra with those of relevant literature. According to the change of metabolite content, the metabolic effect of curcumin and baicalein was explored.

Results:

Five and six metabolites of CUR and BAI in zebrafish were identified by LC-MS/MS, respectively. Their metabolic pathways in zebrafish were glucuronidation and sulfation. Reduction and methylation reactions also occurred for CUR and BAI, respectively. In addition, after combined exposure of both the drugs, CUR reduced the BAI glucuronide metabolites and inhibited the metabolism of BAI in zebrafish, which is consistent with the mammalian metabolism.

Conclusion:

Using LC-MS/MS analysis, zebrafish is a feasible model for drug metabolism study. The results of metabolic study indicated that CUR might affect the therapeutic effect of BAI.

Analysis of the prognostic significance of solute carrier (SLC) family 39 genes in breast cancer

BACKGROUND

Breast cancer (BC) is the most common malignancy in females and remains a main cause of cancer-associated death worldwide. The solute carrier (SLC) groups of membrane transport proteins, which control the influx of zinc, participate in ranging of physiological processes and may provide novel therapeutic targets of cancers. However, the prognostic values of individual SLC family 39 (SLC39A) genes in patients with BC are not clarified.

MATERIALS AND METHODS

The mRNA expression of SLC family 39 genes in BC was evaluated by using the UALCAN database. The prognostic values of overall survival (OS) of SLC family 39 genes in patients with BC were investigated by Kaplan-Meier plotter. The survival analysis of cells was determined by Project Achilles.

RESULTS

The analytic results suggested that SLC39A1, SLC39A3, SLC39A4, SLC39A5, SLC39A6, SLC39A7, SLC39A9, SLC39A10, SLC39A11 and SLC39A13 were significantly up-regulated in BC tissues compared with normal breast tissues. However, SLC39A8 and SLC39A14 were expressed higher in normal tissues than in BC tissues. High expression of SLC39A2, SLC39A3, SLC39A4, SLC39A5, SLC39A7, SLC39A12 and SLC39A13 was significantly associated with worse OS in patients with BC. In contrast, high mRNA levels of SLC39A6 and SLC39A14 indicated favorable OS. Through subgroup analysis, all abnormal expressed SLC family members were correlated with prognoses of patients with specific BC. Moreover, SLC39A7 was associated with proliferation and cloning of BC.

CONCLUSIONS

Our results suggested that SLC family 39 members were promising prognostic biomarkers of BC. The SLC39A7 played a key role in growth and survival of BC cells.

Isoimperatorin Induces Apoptosis of Nasopharyngeal Carcinoma Cells via the MAPK/ERK1/2 Signaling Pathway

Objective

To investigate the effect of isoimperatorin on nasopharyngeal carcinoma CNE2 cell apoptosis and the role of the MAPK/ERK1/2 signaling pathway in inducing apoptosis.

Methods

Real-time cellular analysis technology (RTCA) and MTT were used to detect cell proliferation; Annexin V-FITC/PI dual-fluorescence flow cytometry analysis, Hoechst 33342 staining, and mitochondrial membrane potential detection kit were used to detect cell apoptosis; western blot was used to detect protein expression.

Results

Different concentrations of isoimperatorin (10 μM, 20 μM, 20 μM, 20 μM, 20 μM, 20 μM, 20 μM, 20 

Conclusion

Isoimperatorin can induce nasopharyngeal carcinoma CNE2 cell apoptosis through the MAPK/ERK1/2 signaling pathway.

Baicalein inhibits the growth of oral squamous cell carcinoma cells by downregulating the expression of transcription factor Sp1

Oral squamous cell carcinoma (OSCC), the most common malignancy of the oral cavity, accounts for >90% of all diagnosed oral cancer cases. Baicalein, a naturally derived compound, has been shown to alter p65 and the nuclear factor (NF)‑κB pathway, thus exerting cytotoxic effects on various tumor cell types. However, the mechanism of action of baicalein in OSCC has not been fully elucidated. In the present study, the proliferation of OSCC cells treated with baicalein was examined using a CCK‑8 assay. The effects of baicalein on the cell cycle and apoptosis of OSCC cells were determined by flow cytometric analyses. The expression of specificity protein 1 (Sp1), p65 and p50 at the mRNA and protein levels was determined by reverse transcription‑quantitative PCR and western blot analysis, respectively. The results of the present study demonstrated that baicalein suppresses the proliferation of OSCC cell lines in vivo and in vitro. Baicalein also induced apoptosis of OSCC cells and arrested the cell cycle at the G0/G1 phase. Baicalein inhibited the expression of Sp1, p65 and p50 by downregulating the relative mRNA levels. Baicalein reduced the activity of NF‑κB in OSCC cells. Knockdown of Sp1 also resulted in reduced expression of p65 and p50. In addition, Sp1 silencing enhanced the effects of baicalein. In conclusion, the present study demonstrated that baicalein suppresses the growth of OSCC cells through an Sp1/NF‑κB‑dependent mechanism.

CRISPR/Cas9-mediated LMP1 knockout inhibits Epstein-Barr virus infection and nasopharyngeal carcinoma cell growth

Background

A strong association between Epstein-Barr virus (EBV) infection and nasopharyngeal carcinoma (NPC) has been widely recognized in recent decades. The aim of the present study was to investigate latent membrane protein 1 (LMP1) regulation of nasopharyngeal carcinoma (NPC) CNE-2 cell growth and then examine the effects of LMP1-knockout with CRISPR (Clustered Regularly Interspaced Short Palindromic Repeats)/Cas9on Epstein-Barr virus (EBV) infection and CNE-2 cell growth.

Methods

Human NPC CNE-2 cells were infected with the recombinant LMP1- and LMP2A-carrying lentivirus, and then examined for cell growth with the colony forming assay as well as for the activation of transcription of eukaryotic translation initiation factor 4E (eIF4E) with reverse-transcriptase quantitative polymerase chain reaction (RT-qPCR) and western blot. CRISPR/Cas9-mediated knockout of LMP1 or LMP2A was performed with a single-guide RNA (sgRNA) targeting sequences within LMP1 or LMP2A. The knockout effect and the EBV proliferation were examined with RT-qPCR, western blot and cell growth assay.

Results

LMP1 overexpression promoted CNE-2 cell growth, compared to LMP2A overexpression. Loss-of-function experiments confirmed that eukaryotic translation initiation factor 4E (eIF4E) upregulation mediated this effect. LMP1 knockout significantly inhibited EBV proliferation in CNE-2 cells and markedly inhibited LMP1-mediated promotion of cell growth. The knockout of either LMP1 or LMP2A blocked the eIF4E activation, which is induced either by the EBV infection or by the overexpression of LMP1 or LMP2A.

Conclusion

We confirmed the LMP1-mediated promotion of NPC cell growth. Such promotion can be effectively blocked by CRISPR/Cas9-mediated LMP1 knockout. Precise LMP1 knockout might be a promising method for targeted inhibition of EBV infection and NPC cell growth.

Curcumin Inhibits Proliferation of Epstein-Barr Virus-Associated Human Nasopharyngeal Carcinoma Cells by Inhibiting EBV Nuclear Antigen 1 Expression

This investigation aims to study the effect of curcumin on the proliferation, cycle arrest, and apoptosis of Epstein-Barr virus- (EBV-) positive nasopharyngeal carcinoma (NPC) cells. EBV⁺ NPC cells were subjected to curcumin treatment. The cell viability was evaluated with the CCK-8. Cell cycle and apoptosis were analyzed by flow cytometry analysis. Expression (protein and mRNA) levels were detected with western blotting and quantitative real-time PCR, respectively. Curcumin efficiently reduced the viability of EBV⁺ NPC cells. Curcumin induced the cycle arrest of the HONE1 and HK1-EBV cells positive for EBV. Moreover, curcumin treatment promoted the NPC cell apoptosis, via the mitochondria- and death receptor-mediated pathways. Furthermore, curcumin decreased the expression of EBNA1 in the HONE1 and HK1-EBV cells and inhibited the transcriptional level of EBNA1 in the HeLa cells. Curcumin induced EBNA1 degradation via the proteasome-ubiquitin pathway. In addition, curcumin inhibited the proliferation of HONE1 and HK1-EBV cells positive for EBV, probably by decreasing the expression level of EBNA1. In both the HONE1 and HK1-EBV cells, curcumin inhibited the EBV latent and lytic replication. Curcumin could reduce the EBNA1 expression and exert antitumor effects against NPC in vitro.

Epstein-Barr virus (EBV) reactivation and therapeutic inhibitors

Epstein-Barr virus (EBV) is a ubiquitous human virus which infects almost all humans during their lifetime and following the acute phase, persists for the remainder of the life of the individual. EBV infects B lymphocytes leading to their immortalisation, with persistence of the EBV genome as an episome. In the latent phase, EBV is prevented from reactivating through efficient cytotoxic cellular immunity. EBV reactivates (lytic phase) under conditions of psychological stress with consequent weakening of cellular immunity, and EBV reactivation has been shown to occur in a subset of individuals with each of a variety of cancers, autoimmune diseases, the autoimmune-like disease, chronic fatigue syndrome/myalgic encephalitis and under other circumstances such as being an inpatient in an intensive care unit. Chronic EBV reactivation is an important mechanism in the pathogenesis of many such diseases, yet is rarely tested for in immunocompetent individuals. This review summarises the pathogenesis of EBV infection, EBV reactivation and its role in disease, and methods which may be used to detect it. Known inhibitors of EBV reactivation and replication are discussed, including drugs licensed for treatment of other herpesviruses, licensed or experimental drugs for various other indications, compounds at an early stage of drug development and nutritional constituents such as vitamins and dietary supplements.

Long non‑coding RNA DANCR promotes nasopharyngeal carcinoma cell proliferation and migration

Aberrant expression of numerous long non‑coding RNAs (lncRNAs) has been reported to be associated with nasopharyngeal carcinoma (NPC). The present study aimed to investigate the expression and function of lncRNA differentiation antagonizing non‑protein coding RNA (DANCR) in NPC pathogenesis. Reverse transcription‑quantitative polymerase chain reaction results suggested that DANCR was significantly upregulated in NPC cells. Overexpression of DANCR promoted 5‑8F cell proliferation and migration, as detected by Cell Counting Kit‑8, colony formation and wound healing assays. DANCR was additionally identified to inhibit apoptosis, as determined by flow cytometric analysis. Furthermore, DANCR knockdown suppressed cell proliferation and migration, and promoted cell apoptosis in SUNE‑1 cell. Western blot analysis suggested that DANCR regulated the phosphorylation of AKT serine/threonine kinase and the protein expression of PTEN in NPC cells. Knockdown of DANCR decreased tumor growth in a xenograft model following subcutaneous injection of SUNE‑1 cells. Collectively, the present results suggested that DANCR regulated the proliferation, migration and apoptosis of NPC cells.

Triptolide inhibits Epstein-Barr nuclear antigen 1 expression by increasing sensitivity of mitochondria apoptosis of nasopharyngeal carcinoma cells

BACKGROUND

Epstein-Barr virus (EBV) is widely found in nasopharyngeal carcinoma (NPC) tissue and associated with poor prognosis of patients. EBV nuclear antigen 1 (EBNA1) is expressed in all NPC tumors and plays multiple biological roles in both virus and host cells. Triptolide is a natural product extracted from Tripterygium and shows anti-cancer activities. The goal of this work was to illustrate the anti-cancer effect of triptolide and elucidate a novel anti-apoptotic mechanism of EBNA1 in NPC cells encountered with triptolide.

METHODS

In the present study, a CCK-8 assay was used to analyze the proliferation of NPC cells treated with triptolide in a dose- and time-dependent ways. Effects of triptolide on NPC cell cycle and apoptosis were investigated by flow cytometric analysis. EBNA1 expression in mRNA and protein levels was determined by quantitative real-time PCR and Western blot, respectively.

RESULTS

Our results showed that triptolide effectively inhibited proliferation of NPC cells. Triptolide arrested NPC cell cycles in S phase and induced apoptosis through a caspase-9-dependent apoptosis pathway. Low-dose of triptolide reduced the half-life of EBNA1 and significantly decreased EBNA1 expression by promoting the process of proteasome-ubiquitin pathway. Over-expression of EBNA1, which was independent from EBV genome, effectively attenuated the apoptosis induced by triptolide. In addition, triptolide significantly inhibited proliferations of tumors induced by EBV-positive cells in vivo. Furthermore, EBNA1 were expressed in all NPC biopsies of Chinese patients.

CONCLUSIONS

In summary, our study provides the evidence that triptolide induces EBNA1 degradation and stimulates NPC apoptosis through mitochondria apoptotic pathway. In addition, EBNA1 assists NPC cells to resist triptolide-induced apoptosis through inhibiting caspase-9-dependent apoptotic pathway.