Nasopharyngeal carcinoma with non-squamous phenotype may be a variant of nasopharyngeal squamous cell carcinoma after inhibition of EGFR/PI3K/AKT/mTOR pathway

Nasopharyngeal carcinoma (NPC) is a cancerous tumor that develops in the nasopharynx epithelium and typically has squamous differentiation. The squamous phenotype is evident in immunohistochemistry, with diffuse nuclear positivity for p63 and p40. Nonetheless, a few NPCs have been identified by clinicopathological diagnosis that do not exhibit the squamous phenotype; these NPCs are currently referred to as non-squamous immunophenotype nasopharyngeal carcinomas (NSNPCs). In a previous work, we have revealed similarities between the histological appearance, etiology, and gene alterations of NSNPC and conventional NPC. According to ultrastructural findings, NSNPC still falls under the category of non-keratinized squamous cell carcinoma that is undifferentiated. NSNPC has an excellent prognosis and a low level of malignancy, according to a retrospective investigation. Based on prior research, we investigated the molecular mechanism of NSNPC not expressing the squamous phenotype and its biological behavior. IHC was used to determine the expression of EGFR, PI3K, AKT, p-AKT, mTOR, p-mTOR, Notch, STAT3 and p-STAT3 in a total of 20 NSNPC tissue samples and 20 classic NPC tissue samples. We obtained human NPC cell lines (CNE-2,5-8F) and used EGFR overexpression plasmid and shRNAs to transfect them. To find out whether mRNA and proteins were expressed in the cells, we used Western blotting and qRT-PCR. Cell biological behavior was discovered using the CCK-8 assay, cell migration assay, and cell invasion assay. EGFR, PI3K, p-AKT and p-mTOR proteins were lowly expressed in NSNPC tissues by immunohistochemistry, compared with classical NPC. In the classical NPC cell lines CNE-2 and 5-8F, overexpression EGFR can up-regulate the expression of p63 through the PI3K/AKT/mTOR pathway, and promote the proliferation, migration, and invasion of nasopharyngeal carcinoma cells. At the same time, knockout of EGFR can down-regulate p63 expression through the PI3K/AKT/mTOR pathway, and inhibit the proliferation, migration, and invasion of nasopharyngeal carcinoma cells. The lack of p63 expression in NSNPC was linked with the inhibition of the EGFR/PI3K/AKT/mTOR pathway, and NSNPC may be a variant of classical NPC.

CircCDYL2 bolsters radiotherapy resistance in nasopharyngeal carcinoma by promoting RAD51 translation initiation for enhanced homologous recombination repair

BACKGROUND

Radiation therapy stands to be one of the primary approaches in the clinical treatment of malignant tumors. Nasopharyngeal Carcinoma, a malignancy predominantly treated with radiation therapy, provides an invaluable model for investigating the mechanisms underlying radiation therapy resistance in cancer. While some reports have suggested the involvement of circRNAs in modulating resistance to radiation therapy, the underpinning mechanisms remain unclear.

METHODS

RT-qPCR and in situ hybridization were used to detect the expression level of circCDYL2 in nasopharyngeal carcinoma tissue samples. The effect of circCDYL2 on radiotherapy resistance in nasopharyngeal carcinoma was demonstrated by in vitro and in vivo functional experiments. The HR-GFP reporter assay determined that circCDYL2 affected homologous recombination repair. RNA pull down, RIP, western blotting, IF, and polysome profiling assays were used to verify that circCDYL2 promoted the translation of RAD51 by binding to EIF3D protein.

RESULTS

We have identified circCDYL2 as highly expressed in nasopharyngeal carcinoma tissues, and it was closely associated with poor prognosis. In vitro and in vivo experiments demonstrate that circCDYL2 plays a pivotal role in promoting radiotherapy resistance in nasopharyngeal carcinoma. Our investigation unveils a specific mechanism by which circCDYL2, acting as a scaffold molecule, recruits eukaryotic translation initiation factor 3 subunit D protein (EIF3D) to the 5'-UTR of RAD51 mRNA, a crucial component of the DNA damage repair pathway to facilitate the initiation of RAD51 translation and enhance homologous recombination repair capability, and ultimately leads to radiotherapy resistance in nasopharyngeal carcinoma.

CONCLUSIONS

These findings establish a novel role of the circCDYL2/EIF3D/RAD51 axis in nasopharyngeal carcinoma radiotherapy resistance. Our work not only sheds light on the underlying molecular mechanism but also highlights the potential of circCDYL2 as a therapeutic sensitization target and a promising prognostic molecular marker for nasopharyngeal carcinoma.

Cancer-associated fibroblasts secrete FGF5 to inhibit ferroptosis to decrease cisplatin sensitivity in nasopharyngeal carcinoma through binding to FGFR2

Cisplatin (DDP)-based chemoradiotherapy is one of the standard treatments for nasopharyngeal carcinoma (NPC). However, the sensitivity and side effects of DDP to patients remain major obstacles for NPC treatment. This research aimed to study DDP sensitivity regulated by cancer-associated fibroblasts (CAFs) through modulating ferroptosis. We demonstrated that DDP triggered ferroptosis in NPC cells, and it inhibited tumor growth via inducing ferroptosis in xenograft model. CAFs secreted high level of FGF5, thus inhibiting DDP-induced ferroptosis in NPC cells. Mechanistically, FGF5 secreted by CAFs directly bound to FGFR2 in NPC cells, leading to the activation of Keap1/Nrf2/HO-1 signaling. Rescued experiments indicated that FGFR2 overexpression inhibited DDP-induced ferroptosis, and CAFs protected against DDP-induced ferroptosis via FGF5/FGFR2 axis in NPC cells. In vivo data further showed the protective effects of FGF5 on DDP-triggered ferroptosis in NPC xenograft model. In conclusion, CAFs inhibited ferroptosis to decrease DDP sensitivity in NPC through secreting FGF5 and activating downstream FGFR2/Nrf2 signaling. The therapeutic strategy targeting FGF5/FGFR2 axis from CAFs might augment DDP sensitivity, thus decreasing the side effects of DDP in NPC treatment.

Network pharmacology, molecular docking and experimental study of CEP in nasopharyngeal carcinoma

ETHNOPHARMACOLOGICAL RELEVANCE

The Stephania cephalantha Hayata is an important traditional medicinal plant widely used in traditional medicine to treat cancer. Cepharanthine (CEP) was extracted from the roots of Stephania cephalantha Hayata. It has been found to exhibit anticancer activity in different types of cancer cells. Nevertheless, the activity of CEP against nasopharyngeal carcinoma (NPC) and its underlying mechanism warrant further investigation.

AIMS OF THE STUDY

NPC is an invasive and highly metastatic malignancy that affects the head and neck region. This research aimed to investigate the pharmacological properties and underlying mechanism of CEP against NPC, aiming to offer novel perspectives on treating NPC using CEP.

MATERIALS AND METHODS

In vitro, the pharmacological activity of CEP against NPC was evaluated using the CCK-8 assay. To predict and elucidate the anticancer mechanism of CEP against NPC, we employed network pharmacology, conducted molecular docking analysis, and performed Western blot experiments. In vivo validation was performed through a nude mice xenograft model of human NPC, Western blot and immunohistochemical (IHC) assays to confirm pharmacological activity and the mechanism.

RESULTS

In a dose-dependent manner, the proliferation and clonogenic capacity of NPC cells were significantly inhibited by CEP. Additionally, NPC cell migration was suppressed by CEP. The results obtained from network pharmacology experiments revealed that anti-NPC effect of CEP was associated with 8 core targets, including EGFR, AKT1, PIK3CA, and mTOR. By performing molecular docking, the binding capacity of CEP to the candidate core proteins (EGFR, AKT1, PIK3CA, and mTOR) was predicted, resulting in docking energies of -10.0 kcal/mol for EGFR, -12.4 kcal/mol for PIK3CA, -10.8 kcal/mol for AKT1, and -8.6 kcal/mol for mTOR. The Western blot analysis showed that CEP effectively suppressed the expression of EGFR and the phosphorylation levels of downstream signaling proteins, including PI3K, AKT, mTOR, and ERK. After CEP intervention, a noteworthy decrease in tumor size, without inducing any toxicity, was observed in NPC xenograft nude mice undergoing in vivo treatment. Additionally, IHC analysis demonstrated a significant reduction in the expression levels of EGFR and Ki-67 following CEP treatment.

CONCLUSION

CEP exhibits significant pharmacological effects on NPC, and its mechanistic action involves restraining the activation of the EGFR/PI3K/AKT pathway. CEP represents a promising pharmaceutical agent for addressing and mitigating NPC.

Inhibition of mitochondrial function by approved drugs overcomes nasopharyngeal carcinoma chemoresistance

The development of chemo-resistance in nasopharyngeal carcinoma (NPC) presents a significant therapeutic challenge, and its underlying mechanisms remain poorly understood. In our previous studies, we highlighted the association between isoprenylcysteine carboxylmethyltransferase (ICMT) and chemoresistance in NPC. In this current research, we revealed that both 5-FU and cisplatin-resistant NPC cells exhibited elevated mitochondrial function and increased expression of mitochondrial genes, independent of ICMT. Our investigations further showed that classic mitochondrial inhibitors, such as oligomycin, antimycin, and rotenone, were notably more effective in reducing viability in chemo-resistant NPC cells compared to parental cells. Moreover, we identified two antimicrobial drugs, tigecycline and atovaquone, recognized as mitochondrial inhibitors, as potent agents for decreasing chemo-resistant NPC cells by targeting mitochondrial respiration. Remarkably, tigecycline and atovaquone, administered at tolerable doses, inhibited chemo-resistant NPC growth in mouse models and extended overall survival rates. This work unveils the efficacy of mitochondrial inhibition as a promising strategy to overcome chemo-resistance in NPC. Additionally, our findings highlight the potential repurposing of clinically available drugs like tigecycline and atovaquone for treating NPC patients who develop chemoresistance.

PQR309, a dual PI3K/mTOR inhibitor, synergizes with gemcitabine by impairing the GSK-3β and STAT3/HSP60 signaling pathways to treat nasopharyngeal carcinoma

End-stage nasopharyngeal carcinoma (NPC) has unsatisfactory survival. The limited benefit of chemotherapy and the scarcity of targeted drugs are major challenges in NPC. New approaches to treat late-stage NPC are urgently required. In this study, we explored whether the dual PI3K/mTOR inhibitor, PQR309, exerted a favorable antineoplastic effect and sensitized the response to gemcitabine in NPC. We observed that PI3K expression was positive and elevated in 14 NPC cell lines compared with that in normal nasopharygeal cell lines. Patients with NPC with higher PI3K levels displayed poorer prognosis. We subsequently showed that PQR309 alone effectively decreased the viability, invasiveness, and migratory capability of NPC cells and neoplasm development in mice xenograft models, and dose-dependently induced apoptosis. More importantly, PQR309 remarkably strengthened the anti-NPC function of gemcitabine both in vivo and in vitro. Mechanistically, PQR309 sensitized NPC to gemcitabine by increasing caspase pathway-dependent apoptosis, blocking GSK-3β and STAT3/HSP60 signaling, and ablating epithelial-mesenchyme transition. Thus, targeting PI3K/mTOR using PQR309 might represent a treatment option to promote the response to gemcitabine in NPC, and provides a theoretical foundation for the study of targeted drugs combined with chemotherapy for NPC.

Nasopharyngeal Carcinoma Cell Lines: Reliable Alternatives to Primary Nasopharyngeal Cells?

Nasopharyngeal carcinoma (NPC) is a type of cancer that originates from the mucosal lining of the nasopharynx and can invade and spread. Although contemporary chemoradiotherapy effectively manages the disease locally, there are still challenges with locoregional recurrence and distant failure. Therefore, it is crucial to have a deeper understanding of the molecular basis of NPC cell movement in order to develop a more effective treatment and to improve patient survival rates. Cancer cell line models are invaluable in studying health and disease and it is not surprising that they play a critical role in NPC research. Consequently, scientists have established around 80 immortalized human NPC lines that are commonly used as in vitro models. However, over the years, it has been observed that many cell lines are misidentified or contaminated by other cells. This cross-contamination leads to the creation of false cell lines that no longer match the original donor. In this commentary, we discuss the impact of misidentified NPC cell lines on the scientific literature. We found 1159 articles from 2000 to 2023 that used NPC cell lines contaminated with HeLa cells. Alarmingly, the number of publications and citations using these contaminated cell lines continued to increase, even after information about the contamination was officially published. These articles were most commonly published in the fields of oncology, pharmacology, and experimental medicine research. These findings highlight the importance of science policy and support the need for journals to require authentication testing before publication.

MiRNA-296-5p promotes the sensitivity of nasopharyngeal carcinoma cells to cisplatin via targeted inhibition of STAT3/KLF4 signaling axis

Improving drug sensitivity is an important strategy in chemotherapy of cancer and accumulating evidence indicates that miRNAs are involved in the regulation of drug sensitivity, but the specific mechanism is still unclear. Our previous study has found that miR-296-5p was significantly downregulated in nasopharyngeal carcinoma (NPC). Here, we aim to explore whether miR-296-5p is involved in regulating cisplatin sensitivity in NPC by regulating STAT3/KLF4 signaling axis. The cell proliferation and clonogenic capacity of NPC cells were evaluated by CCK8 Assay and plate colony assay, respectively. The Annexin V-FITC staining kit was used to determine and quantify the apoptotic cells using flow cytometry. The drug efflux ability of NPC cells were determined by Rhodamine 123 efflux experiment. The expression of miR-296-5p, apoptosis-related genes and protein in NPC cell lines were detected by qPCR and Western blot, respectively. Animal study was used to evaluate the sensitivity of NPC cells to DDP treatment in vivo. Our results showed that elevated miR-296-5p expression obviously promoted the sensitivity of NPC cells to DDP by inhibiting cell proliferation and clonogenic capacity, and inducing apoptosis. In addition, we found that miR-296-5p inhibited the expression of STAT3 and KLF4 in NPC cells, while overexpression of exogenous STAT3 reversed miR-296-5p-mediated enhancement in cell death of DDP-treated NPC cells. In vivo studies further confirmed that miR-296-5p promotes the sensitivity of NPC cells to DDP treatment. miRNA-296-5p enhances the drug sensitivity of nasopharyngeal carcinoma cells to cisplatin via STAT3/KLF4 signaling pathway.

Methyltransferase-like 3-mediated m6A modification of miR-1908-5p contributes to nasopharyngeal carcinoma progression by targeting homeodomain-only protein homeobox

BACKGROUND

N6-methyladenosine (m6A) modification interacting microRNAs (miRNAs) have been confirmed to participate in nasopharyngeal carcinoma (NPC) progression. This research investigated miR-1908-5p's function and regulatory mechanism in the tumorigenesis of NPC via m6A modification and targeting a key gene.

METHODS

The levels of miR-1908-5p, homeodomain-only protein homeobox (HOPX), and methyltransferase-like 3 (METTL3) expressions were detected via RT-qPCR. The correlation between miR-1908-5p and the HOPX/METTL3 axis, as well as their regulatory mechanism, was investigated by dual luciferase reporter, western blotting, and MeRIP assays. Moreover, the bio-functions of miR-1908-5p, HOPX, and METTL3 in NPC were explored through CCK8, transwell, caspase-3 activity, and xenograft tumor assays.

RESULTS

RT-qPCR results indicated a miR-1908-5p upregulation in NPC. Knocking down miR-1908-5p diminished the NPC cell viability and migration in vitro. In vivo, downregulating miR-1908-5p repressed NPC cell tumor growth. Moreover, HOPX was specifically targeted by miR-1908-5p, and HOPX downregulation led to reversal of the anti-tumor impact of the miR-1908-5p inhibitor against NPC cell malignancy. Also, METTL3 could mediate the m6A modification of miR-1908-5p to regulate its influence on NPC cells.

CONCLUSION

This study demonstrated that the METTL3-mediated m6A modification of miR-1908-5p enhanced the tumorigenesis of NPC by targeting HOPX. These findings propose new insights for NPC diagnosis and therapy.

The role and molecular mechanism of NOP16 in the pathogenesis of nasopharyngeal carcinoma

We aimed to explore the effects of NOP16 on the pathogenesis of nasopharyngeal carcinoma (NPC) and the related mechanism. In this study, the expression level of NOP16 in NPC tissues and adjacent tissues was measured by qRT-polymerase chain reaction (PCR) and immunohistochemistry (IHC) tests. In the in vitro study, the expression levels of NOP16 and RhoA/phosphatidylinositol 3-kinase (PI3K)/Akt/c-Myc and IKK/IKB/NF-κB signalling pathway-related proteins in NPC cells were measured by qRT-PCR and Western blot (WB). CCK8 assays and colony formation assays were used to detect cell proliferation. Transwell assays were used to detect the migration and invasion ability of NPC cells. Flow cytometry and WB were used to measure the level of apoptosis. For the in vivo study, NPC xenograft models were established in nude mice, and tumour weight and volume were recorded. The expression levels of NOP16 and RhoA/PI3K/Akt/c-Myc signalling pathway-related proteins and mRNAs were measured by immunofluorescence, qRT-PCR and WB experiments. In clinical samples, the results of qRT-PCR and IHC experiments showed that the expression level of NOP16 was significantly increased in NPC tissues. In the in vitro study, the results of qRT-PCR and WB experiments showed that NOP16 was significantly increased in NPC cells. The CCK8 assay, colony formation assay, transwell assay and flow cytometry results showed that knocking out NOP16 inhibited the proliferation, migration and invasion of NPC cells and increased apoptosis. WB results showed that knocking out NOP16 inhibited the RhoA/PI3K/Akt/c-Myc and IKK/IKB/NF-κB signalling pathways. These effects were reversed by 740Y-P (PI3K activator). In the in vivo study, knockdown of NOP16 reduced tumour volume and weight and inhibited the RhoA/PI3K/Akt/c-Myc signalling pathway. In conclusion, knockdown of NOP16 inhibited the proliferation, migration and invasion of NPC cells and induced apoptosis by inhibiting the RhoA/PI3K/Akt/c-Myc and IKK/IKB/NF-κB pathways, leading to the malignant phenotype of NPC.

Peritumoral SPARC expression induced by exosomes from nasopharyngeal carcinoma infected Epstein-Barr virus: A poor prognostic marker

Epstein-Barr virus (EBV)-associated nasopharyngeal carcinoma (NPC) cells have high metastatic potential. Recent research has revealed that the interaction of between tumor cells and the surrounding stroma plays an important role in tumor invasion and metastasis. In this study, we showed the prognostic value of expression of SPARC, an extracellular matrix protein with multiple cellular functions, in normal adjacent tissues (NAT) surrounding NPC. In the immunohistochemical analysis of 51 NPC biopsy specimens, SPARC expression levels were significantly elevated in the NAT of EBER (EBV-encoded small RNA)-positive NPC compared to that in the NAT of EBER-negative NPC. Moreover, increased SPARC expression in NAT was associated with a worsening of overall survival. The enrichment analysis of RNA-seq of publicly available NPC and NAT surrounding NPC data showed that high SPARC expression in NPC was associated with epithelial mesenchymal transition promotion, and there was a dynamic change in the gene expression profile associated with interference of cellular proliferation in NAT, including SPARC expression. Furthermore, EBV-positive NPC cells induce SPARC expression in normal nasopharyngeal cells via exosomes. Induction of SPARC in cancer-surrounding NAT cells reduced intercellular adhesion in normal nasopharyngeal structures and promoted cell competition between cancer cells and normal epithelial cells. These results suggest that epithelial cells loosen their own binding with the extracellular matrix as well as stromal cells, facilitating the invasion of tumor cells into the adjacent stroma by activating cell competition. Our findings reveal a new mechanism by which EBV creates a pro-metastatic microenvironment by upregulating SPARC expression in NPC.

ENOX2 inhibition enhances infiltration of effector memory T-cell and mediates response to chemotherapy in immune-quiescent nasopharyngeal carcinoma

INTRODUCTION

The immunosuppressive tumor microenvironment is a major barrier for chemotherapy. Different chemosensitization approaches to reinstate immunological surveillance for cancers that are immune quiescent at the outset, have thus been devised. Cancer-specific ENOX2 expression is correlated with abnormal cell growth and has been proposed as a cellular target for anti-cancer activity. However, the potential effects of ENOX2 on the interaction between immune system and tumor cells remain elusive.

OBJECTIVES

To understand the mechanisms by which tumor-intrinsic ENOX2-mediated alterations in anti-tumor activity of T-cells and response to chemotherapy.

METHODS

In situ multiplexed immunohistochemistry with single cell and bulk RNA sequencing data from nasopharyngeal carcinoma (NPC) human tissues were used to define tumor phenotypes. Two NPC cell lines, with distinct ENOX2 expression, were used in a co-culture platform to study tumor-immune interactions between cancer cells/spheroids and T-cells. The effect of cisplatin treatment with ENOX2 inhibition by idronoxil (IDX) were tested in vitro and in vivo. Multi-parametric flow cytometry was used to characterize T-cell infiltrates in an NPC tumor humanized mouse model treated with combined treatment.

RESULTS

NPC predominantly displayed an immune-excluded profile. This "cold-phenotype" was shown to exhibit higher ENOX2 expression and was associate with poorer progression-free survival (PFS). The therapeutic combination of IDX with cisplatin was effective in promoting CD8+ effector memory T cell (Tem) differentiation and mobilization. This Tem signature was highly cytotoxic, with Tem-mediated preferential lysis of higher ENOX2-expressing NPC cells. A combination-treated humanized mouse model showing dramatic shrinkage in tumors, were intra-tumoral Tem-enriched.

CONCLUSION

Tumor-intrinsic ENOX2 expression is associated with tumor phenotype and PFS in NPC. Targeting ENOX2 with IDX and cisplatin impose qualitative control of T-cell response by preferentially increasing immune cells infiltration, Tem differentiation and tumor suppression. We suggest that ENOX2 inhibition may be a promising therapeutic strategy to enhance the effects of chemotherapy.

FGF19 promotes nasopharyngeal carcinoma progression by inducing angiogenesis via inhibiting TRIM21-mediated ANXA2 ubiquitination

PURPOSE

Nasopharyngeal carcinoma (NPC) has characteristics of high invasion and early metastasis. Most NPC patients present with locoregionally advanced illness when first diagnosed. Therefore, it is urgent to discover NPC biomarkers. Fibroblast growth Factor 19 (FGF19) plays a role in various physiological or pathological processes, including cancer. In this research, we discovered the importance of FGF19 in NPC, and clarified its role in tumour angiogenesis.

METHODS

Western blotting, immunohistochemistry and ELISA were used to investigate FGF19 expression in NPC. Then we took CCK8, colony formation, Transwell and wound healing assays to identify the influence of FGF19 on NPC malignant behaviours. The proliferative and metastatic capacity of FGF19 were evaluated in nude mice and zebrafish. The role of FGF19 in angiogenesis was investigated by tube formation and Matrigel plug angiogenesis assays. We then evaluated the variation in Annexin A2(ANXA2) levels with the treatment of FGF19. Lastly, co-immunoprecipitation and ubiquitination assays were performed to identify the mechanisms involved.

RESULTS

FGF19 levels were elevated in tissues and serum of NPC patients and were associated with poor clinical stages. High expression of FGF19 promoted NPC malignant behaviours. In particular, FGF19 expression was correlated with microvessel density in tissues and NPC-derived FGF19 could accelerate angiogenesis in vitro and in vivo. Mechanistically, FGF19 influenced ANXA2 expression to promote angiogenesis. Moreover, tripartite motif-containing 21(TRIM21) interacted with ANXA2 and was responsible for ANXA2 ubiquitination.

CONCLUSION

FGF19 promoted NPC angiogenesis by inhibiting TRIM21-mediated ANXA2 ubiquitination. It may serve as a noninvasive biomarker for NPC and provides new insights for therapy.

CENPN suppresses autophagy and increases paclitaxel resistance in nasopharyngeal carcinoma cells by inhibiting the CREB-VAMP8 signaling axis

Chemotherapeutic resistance is one of the most common reasons for poor prognosis of patients with nasopharyngeal carcinoma (NPC). We found that CENPN can promote the growth, proliferation and apoptosis resistance of NPC cells, but its relationship with chemotherapeutic resistance in NPC is unclear. Here we verified that the CENPN expression level in NPC patients was positively correlated with the degree of paclitaxel (PTX) resistance and a poor prognosis through analysis of clinical cases. VAMP8 expression was significantly increased after knockdown of CENPN by transcriptome sequencing. We found in cell experiments that CENPN inhibited macroautophagy/autophagy and VAMP8 expression and significantly increased PTX resistance. Overexpression of CENPN reduced the inhibitory effects of PTX on survival, cell proliferation, cell cycle progression and apoptosis resistance in NPC cells by inhibiting autophagy. In turn, knockdown of CENPN can affect the phenotype of NPC cells by increasing autophagy to achieve PTX sensitization. Sequential knockdown of CENPN and VAMP8 reversed the PTX-sensitizing effect of CENPN knockdown alone. Experiments in nude mice confirmed that knockdown of CENPN can increase VAMP8 expression, enhance autophagy and increase the sensitivity of NPC cells to PTX. Mechanistic studies showed that CENPN inhibited the translocation of p-CREB into the nucleus of NPC cells, resulting in the decreased binding of p-CREB to the VAMP8 promoter, thereby inhibiting the transcription of VAMP8. These results demonstrate that CENPN may be a marker for predicting chemotherapeutic efficacy and a potential target for inducing chemosensitization to agents such as PTX.Abbreviations: 3-MA: 3-methyladenine; ATG5: autophagy related 5; CENPN: centromere protein N; CQ: chloroquine; CREB: cAMP responsive element binding protein; ChIP: chromatin immunoprecipitation assay; IC50: half-maximal inhibitory concentration; LAMP2A: lysosomal associated membrane protein 2A; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; NPC: nasopharyngeal carcinoma; NPG: nasopharyngitis; oeCENPN: overexpressed CENPN; PTX: paclitaxel; RAPA: rapamycin; RNA-seq: transcriptome sequencing; shCENPN: small hairpin RNA expression vector targeting the human CENPN gene; shCENPN-shVAMP8: sequential knockdown targeting the human CENPN gene and VAMP8 gene; shVAMP8: small hairpin RNA expression vector targeting the human VAMP8 gene; TEM: transmission electron microscopy; TIR: tumor inhibitory rate; VAMP8: vesicle associated membrane protein 8.

USP7 inhibits the progression of nasopharyngeal carcinoma via promoting SPLUNC1-mediated M1 macrophage polarization through TRIM24

Reprogramming of macrophages toward an M1 phenotype is a novel strategy to induce anticancer immunity. However, the regulatory mechanisms of M1 macrophage polarization and its functional roles in nasopharyngeal carcinoma (NPC) progression need to be further explored. Here we found that SPLUNC1 was highly expressed and responsible for M1 macrophage polarization. JAK/STATs pathway activation was involved in SPLUNC1-mediated M1 macrophage polarization. Importantly, regulation of SPLUNC1 in macrophages affected CM-mediated influence on NPC cell proliferation and migration. Mechanistically, USP7 deubiquitinated and stabilized TRIM24, which promoted SPLUNC1 expression via recruitment of STAT3 in M1 macrophages. Depletion of TRIM24 inhibited M1 macrophage polarization, which facilitated NPC cell growth and migration. However, over-expression of USP7 exhibited the opposite results and counteracted the tumorigenic effect of TRIM24 silencing. Finally, the growth and metastasis of NPC cells in vivo were repressed by USP7-induced M1 macrophage polarization via modulating TRIM24/SPLUNC1 axis. USP7 delayed NPC progression via promoting macrophage polarization toward M1 through regulating TRIM24/SPLUNC1 pathway, providing evidence for the development of effective antitumor immunotherapies for NPC.

Ulinastatin inhibits the metastasis of nasopharyngeal carcinoma by involving uPA/uPAR signaling

Distant metastasis is the primary reason for treatment failure in patients with nasopharyngeal carcinoma (NPC). In this study, we investigated the effect of ulinastatin (UTI) on NPC metastasis and its underlying mechanism. Highly-metastatic NPC cell lines S18 and 58F were treated with UTI and the effect on cell proliferation, migration, and invasion were determined by MTS and Transwell assays. S18 cells with luciferase-expressing (S18-1C3) were injected into the left hind footpad of nude mice to establish a model of spontaneous metastasis from the footpad to popliteal lymph node (LN). The luciferase messenger RNA (mRNA) was measured by quantitative polymerase chain reaction (qPCR), and the metastasis inhibition rate was calculated. Key molecular members of the UTI-related uPA, uPAR, and JAT/STAT3 signaling pathways were detected by qPCR and immunoblotting. UTI suppressed the migration and infiltration of S18 and 5-8F cells and suppressed the metastasis of S18 cells in vivo without affecting cell proliferation. uPAR expression decreased from 24 to 48 h after UTI treatment. The antimetastatic effect of UTI is partly due to the suppression of uPA and uPAR. UTI partially suppresses NPC metastasis by downregulating the expression of uPA and uPAR.

Metabolic reprogramming in nasopharyngeal carcinoma: Mechanisms and therapeutic opportunities

The high prevalence of metabolic reprogramming in nasopharyngeal carcinoma (NPC) offers an abundance of potential therapeutic targets. This review delves into the distinct mechanisms underlying metabolic reprogramming in NPC, including enhanced glycolysis, nucleotide synthesis, and lipid metabolism. All of these changes are modulated by Epstein-Barr virus (EBV) infection, hypoxia, and tumor microenvironment. We highlight the role of metabolic reprogramming in the development of NPC resistance to standard therapies, which represents a challenging barrier in treating this malignancy. Furthermore, we dissect the state of the art in therapeutic strategies that target these metabolic changes, evaluating the successes and failures of clinical trials and the strategies to tackle resistance mechanisms. By providing a comprehensive overview of the current knowledge and future directions in this field, this review sets the stage for new therapeutic avenues in NPC.

Parkin enhances sensitivity of paclitaxel to nasopharyngeal carcinoma by activating BNIP3/NIX-mediated mitochondrial autophagy

As a malignant head and neck cancer, nasopharyngeal carcinoma (NPC) has high morbidity. Parkin expression has been reported to be reduced in NPC tissues and its upregulation could enhance paclitaxel-resistant cell cycle arrest. This study was performed to explore the possible mechanism of Parkin related to B-cell lymphoma-2 (Bcl-2)/adenovirus E1B 19 kDa interacting protein 3 (BNIP3)/BNIP3-like (NIX)-mediated mitochondrial autophagy in NPC cells. Initially, after Parkin overexpression or silencing, cell viability and proliferation were evaluated by lactate dehydrogenase and colony formation assays. JC-1 staining was used to assess the mitochondrial membrane potential. In addition, the levels of cellular reactive oxygen species (ROS) and mitochondrial ROS were detected using DCFH-DA staining and mitochondrial ROS (MitoSOX) red staining. The expression of proteins was measured using Western blot. Results showed that Parkin overexpression inhibited, whereas Parkin knockdown promoted the proliferation of paclitaxel-treated NPC cells. Besides, Parkin overexpression induced, whereas Parkin knockdown inhibited mitochondrial apoptosis in paclitaxel-treated NPC cells, as evidenced by the changes of Cytochrome C (mitochondria), Cytochrome C (cytoplasm), BAK, and Bcl-2 expression. Moreover, the levels of ROS, mitochondrial membrane potential, and LC3II/LC3I in paclitaxel-treated C666-1 cells were hugely elevated by Parkin overexpression and were all declined by Parkin knockdown in CNE-3 cells. Furthermore, Parkin upregulation activated, whereas Parkin downregulation inactivated BNIP3/NIX signaling. Further, BNIP3 silencing or overexpression reversed the impacts of Parkin upregulation or downregulation on the proliferation and mitochondrial apoptosis of paclitaxel-treated NPC cells. Particularly, Mdivi-1 (mitophagy inhibitor) or rapamycin (an activator of autophagy) exerted the same effects on NPC cells as BNIP3 silencing or overexpression, respectively. Collectively, Parkin overexpression activated BNIP3/NIX-mediated mitochondrial autophagy to enhance sensitivity to paclitaxel in NPC.

c-Met is a chimeric antigen receptor T-cell target for treating recurrent nasopharyngeal carcinoma

BACKGROUND AIMS

Radiation therapy is the standard treatment for patients with nasopharyngeal carcinoma (NPC), but relapse occurs in 10% to 20% of patients. The treatment of recurrent nasopharyngeal carcinoma (rNPC) remains challenging. Chimeric antigen receptors (CAR)-T-cell therapy has achieved good outcomes in the treatment of leukemia and seems to be a promising therapeutic strategy for solid tumors. c-Met has been found to be highly expressed in multiple cancer types, and the activation of c-Met leads to the proliferation and metastasis of cancer cells. However, the expression of c-Met in rNPC tissues and whether it can be used as a target for CAR-T therapy in rNPC remain to be investigated.

METHODS

We detected the expression of c-Met in 24 primary human rNPC tissues and three NPC cell lines and constructed two different antibody-derived anti-c-Met CARs, namely, Ab928z and Ab1028z. To estimate the function of these two different c-Met-targeted CAR-T cells, CD69 expression, cytotoxicity and cytokine secretion of CAR-T cells were assessed after coculture with target cells. A cell line-derived xenograft mouse model also was used to evaluate these two anti-c-Met CAR-T cells. Furthermore, we determined whether combination with an anti-EGFR antibody could promote the antitumor effect of CAR-T cells in a patient-derived xenograft mouse model.

RESULTS

High c-Met expression was detected in 23 of 24 primary human rNPC tissues by immunohistochemistry staining and in three NPC cell lines by flow cytometry. Ab928z-T cells and Ab1028z-T cells showed significantly upregulated expression of CD69 after coculture with targeted cells. However, Ab1028z-T cells showed superior cytokine secretion and antitumor activity. Furthermore, Ab1028z-T cells effectively suppressed tumor growth compared with control CAR-T cells, and the combination with nimotuzumab further enhanced the tumor-clearing ability of Ab1028z-T cells.

CONCLUSIONS

We found that c-Met is highly expressed in rNPC tissues and confirmed its potential as a CAR-T target for rNPC. Our study provides a new idea for the clinical treatment of rNPC.

RASSF1A promotes radiosensitivity in nasopharyngeal carcinoma by promoting FoxO3a and inhibiting the Nrf2/TXNRD1 signaling pathway

Radiotherapy is widely used as the first-line treatment for nasopharyngeal carcinoma (NPC). However, the resistance of some patients to treatment lowers its clinical effectiveness. Compared to typical epithelial cells, NPC markedly lowers the Ras-association domain family 1A (RASSF1A) protein expression. RASSF1A overexpression sensitizes NPC cells to radiotherapy. Mechanistically, RASSF1A promotes the expression of Forkhead box O3a (FoxO3a) in the nucleus and inhibits the Nuclear factor E2-related factor 2 (Nrf2) signaling pathway via binding to the Kelch-like ECH-associated protein 1 (Keap1) promoter. Through elevating intracellular ROS levels, RASSF1A overexpression inhibits the expression of thioredoxin reductase 1 (TXNRD1), a crucial Nrf2 target gene, and increases NPC sensitivity to radiation. Immunohistochemical staining of NPC tissue sections revealed that the expression of RASSF1A is negatively correlated with that of TXNRD1. The traditional Chinese medicine component andrographolide (AGP), which induces RASSF1A expression, increased the sensitivity of NPC cells to radiotherapy in vitro and in vivo. Our findings implied that RASSF1A increases the sensitivity of NPC to radiation by increasing FoxO3a expression in the nucleus, inhibiting the Nrf2/TXNRD1 signaling pathway, and elevating intracellular ROS levels. AGP targets RASSF1A and may be a promising adjuvant sensitizer for enhancing radiosensitivity in NPC.

Regorafenib inhibits growth, survival and angiogenesis in nasopharyngeal carcinoma and is synergistic with Mcl-1 inhibitor

OBJECTIVES

Regorafenib is an oral multi-kinase inhibitor approved for various metastatic/advanced cancers, and has been investigated in clinical trials in many other tumour entities. The purpose of this study was to evaluate the therapeutic potential of regorafenib for nasopharyngeal carcinoma (NPC).

METHODS

Cellular proliferation, survival, apoptosis and colony formation assays were performed and combination index was determined. NPC xenograft tumour models were established. In vitro and In vivo angiogenesis assays were performed.

KEY FINDINGS

Regorafenib is effective against a panel of NPC cell lines regardless of cellular origin and genetic profiling while sparing normal nasal epithelial cells. The predominant inhibitory effects of regorafenib in NPC are anchorage-dependent and anchorage-independent growth rather than survival. Apart from tumour cells, regorafenib potently inhibits angiogenesis. Mechanistically, regorafenib inhibits multiple oncogenic pathways including Raf/Erk/Mek and PI3K/Akt/mTOR. Regorafenib decreases Bcl-2 but not Mcl-1 level in NPC cells. The in vitro observations are evident in in vivo NPC xenograft mouse model. The combination of Mcl-1 inhibitor with regorafenib is synergistic in inhibiting NPC growth without causing systemic toxicity in mice.

CONCLUSIONS

Our findings also support further clinical investigation of regorafenib and Mcl-1 inhibitor for NPC treatment.

LINC01376 promotes nasopharyngeal carcinoma tumorigenesis by competitively binding to the SP1/miR-4757/IGF1 axis

The long non-coding RNA (lncRNA)-microRNA (miRNA) interaction network plays a crucial part in the pathogenesis of nasopharyngeal carcinoma (NPC). Here, we discovered a relationship between LINC01376 and miR-4757 in NPC tumor development. First, LINC01376 was abnormally overexpressed in NPC tissues and cells, and its elevated expression was associated with advanced clinical stage and shorter distant metastasis-free survival time. Moreover, biological experiments showed that LINC01376 facilitated the proliferative, invasive, and migratory abilities of NPC cells in vitro and in vivo. Mechanistically, bioinformatics and RT-qPCR assays revealed that LINC01376 knockdown upregulated the expression level of downstream miR-4757, including miR-4757 primary transcript (pri-miR-4757) and mature miR-4757. Furthermore, LINC01376 competitively sponged the transcription factor SP1 and reduced its enrichment in the upstream promoter region of miR-4757 to repress miR-4757 expression. Finally, insulin-like growth factor 1(IGF1) was identified as the target of miR-4757. Rescue experiments indicated that LINC01376 accelerated NPC cell proliferation, migration, and invasion through the miR-4757-5p/IGF1 axis. In conclusion, the SP1/miR-4757/IGF1 axis, which is regulated by LINC01376 in NPC deterioration and metastasis, is expected to provide new insights into the molecular mechanism of NPC carcinogenesis.

Expression of cytoskeleton-associated protein 4 is associated with poor prognosis and metastasis in nasopharyngeal carcinoma

Cytoskeleton-associated protein 4 (CKAP4) acts as a key transmembrane protein that connects the endoplasmic reticulum (ER) to microtubule dynamics. Researchers have not examined the roles of CKAP4 in nasopharyngeal carcinoma (NPC). The study aimed at evaluating the prognostic value and metastasis-regulating effect of CKAP4 in NPC. CKAP4 protein could be observed in 86.36% of 557 NPC specimens but not in normal nasopharyngeal epithelial tissue. According to immunoblot assays, NPC cell lines presented high CKAP4 expression relative to NP69 immortalized nasopharyngeal epithelial cells. Moreover, CKAP4 was highly expressed at the NPC tumor front and in matched liver, lung, and lymph node metastasis samples. Furthermore, high CKAP4 expression reported poor overall survival (OS) and presented a positive relevance to tumor (T) classification, recurrence, and metastasis. According to multivariate analysis, CKAP4 could independently and negatively predict patients' prognosis. Stable knockdown of CKAP4 expression in NPC cells inhibited cell migration, invasion and metastasis in vitro and in vivo. Moreover, CKAP4 promoted epithelial-mesenchymal transition (EMT) in NPC cells. CKAP4 knockdown was followed by the downregulation of the interstitial marker vimentin, and upregulation of the epithelial marker E-cadherin. In NPC tissues, high CKAP4 expression exhibited a positive relevance to vimentin expression and a negative relevance to E-cadherin expression. In conclusion, CKAP4 is an independent predictor of NPC, and CKAP4 might contribute NPC progression and metastasis, which may be involved in EMT with vimentin and E-cadherin.

Radiosensitization of Nasopharyngeal Carcinoma by Graphene Oxide Nanosheets to Reduce Bcl-2 Level

There are many treatments for nasopharyngeal carcinoma (NPC), but none of them are very effective. Radiotherapy is used extensively in NPC treatment, but radioresistance is a major problem. Graphene oxide (GO) has been previously studied in cancer treatment, and this study is aimed to explore its role in radiosensitization of NPC. Therefore, graphene oxide nanosheets were prepared, and the relationship between GO and radioresistance was explored. The GO nanosheets were synthesized by a modified Hummers' method. The morphologies of the GO nanosheets were characterized by field-emission environmental scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The morphological changes and radiosensitivity of C666-1 and HK-1 cells with or without the GO nanosheets were observed by an inverted fluorescence microscopy and laser scanning confocal microscopy (LSCM). Colony formation assay and Western Blot were applied for analysis of NPC radiosensitivity. The as-synthesized GO nanosheets have lateral dimensions (sizes ∼1 μm) and exhibit a thin wrinkled two-dimensional lamellar structure with slight folds and crimped edges (thickness values ∼1 nm). C666-1 cells with the GO was significantly changed the morphology of cells postirradiation. The full field of view visualized by a microscope showed the shadow of dead cells or cell debris. The synthesized graphene oxide nanosheets inhibited cell proliferation, promoted cell apoptosis, and inhibited the expression of Bcl-2 in C666-1 and HK-1 cells but increased the level of Bax. The GO nanosheets could affect the cell apoptosis and reduce the pro-survival protein Bcl-2 related to the intrinsic mitochondrial pathway. The GO nanosheets could enhance radiosensitivity, which might be a radioactive material in NPC cells.

Knockdown of RFC4 inhibits the cell proliferation of nasopharyngeal carcinoma in vitro and in vivo

Nasopharyngeal carcinoma (NPC) is a malignant tumor that mainly occurs in East and Southeast Asia. Although patients benefit from the main NPC treatments (e.g., radiotherapy and concurrent chemotherapy), persistent and recurrent diseases still occur in some NPC patients. Therefore, investigating the pathogenesis of NPC is of great clinical significance. In the present study, replication factor c subunit 4 (RFC4) is a key potential target involved in NPC progression via bioinformatics analysis. Furthermore, the expression and mechanism of RFC4 in NPC were investigated in vitro and in vivo. Our results revealed that RFC4 was more elevated in NPC tumor tissues than in normal tissues. RFC4 knockdown induced G2/M cell cycle arrest and inhibited NPC cell proliferation in vitro and in vivo. Interestingly, HOXA10 was confirmed as a downstream target of RFC4, and the overexpression of HOXA10 attenuated the silencing of RFC4-induced cell proliferation, colony formation inhibition, and cell cycle arrest. For the first time, this study reveals that RFC4 is required for NPC cell proliferation and may play a pivotal role in NPC tumorigenesis.

Enhanced motility and interaction of nasopharyngeal carcinoma with epithelial cells in confined microwells

The three-dimensional (3D) structure of the extracellular matrix and cell-cell contacts are two important cues to altering cell migration behavior and the tumor formation process. In this work, we designed and fabricated microwell arrays with a grating-patterned bottom in polydimethylsiloxane platforms to systematically study the effects of confinement, changes in topography, and cell-cell contacts on the migration behavior of nasopharyngeal carcinoma (NPC43) and immortalized nasopharyngeal epithelial (NP460) cells by time-lapse imaging. When two types of cells were co-cultured in microwells, the migration speed and spreading area of NPC43 cells were significantly increased, which might be attributed to the heterotypic cell-cell contacts with NP460 cells. On a flat surface, NPC43 cells could not form clusters due to the frequent interruptions by the active movements of NP460 cells. However, in 3D microwell arrays, clusters of NPC43 cells formed on the bottom surface while the majority of NP460 cells migrated onto the sidewalls. These cell clusters could be further processed to form spheroids for drug screening. These results also revealed that the 3D microenvironments and cell-cell contacts could have significant implications for NPC cell migration and initiation of tumor formation, which will provide insight for NPC progression and dissemination.

The miRNA-185-5p/STIM1 Axis Regulates the Invasiveness of Nasopharyngeal Carcinoma Cell Lines by Modulating EGFR Activation-Stimulated Switch from E- to N-Cadherin

Distant metastasis remains the primary cause of treatment failure and suggests a poor prognosis in nasopharyngeal carcinoma (NPC). Epithelial-mesenchymal transition (EMT) is a critical cellular process for initiating a tumor invasion and remote metastasis. Our previous study showed that the blockage of the stromal interaction molecule 1 (STIM1)-mediated Ca²⁺ signaling blunts the Epstein-Barr virus (EBV)-promoted cell migration and inhibits the dissemination and lymphatic metastasis of NPC cells. However, the upstream signaling pathway that regulates the STIM1 expression remains unknown. In this follow-up study, we demonstrated that the miRNA-185-5p/STIM1 axis is implicated in the regulation of the metastatic potential of 5-8F cells, a highly invasive NPC cell line. We demonstrate that the knockdown of STIM1 attenuates the migration ability of 5-8F cells by inhibiting the epidermal growth factor receptor (EGFR) phosphorylation-induced switch from E- to N-cadherin in vitro. In addition, the STIM1 knockdown inhibited the locoregional lymphatic invasion of the 5-8F cells in mice. Furthermore, we identified miRNA-185-5p as an upstream regulator that negatively regulates the expression of STIM1. Our findings suggest that the miRNA-185-5p/STIM1 axis regulates the invasiveness of NPC cell lines by affecting the EGFR activation-modulated cell adhesiveness. The miRNA-185-5p/STIM1 axis may serve as a potentially effective therapeutic target for the treatment of NPC.

MiR-302c-5p affects the stemness and cisplatin resistance of nasopharyngeal carcinoma cells by regulating HSP90AA1

Nasopharyngeal carcinoma (NPC) is one of the most frequent malignant tumors diagnosed in China. Cisplatin is one of the most commonly used anticancer drugs containing platinum in combined chemotherapy. The molecular mechanism of NPC is still largely unknown, and we aim to spare no effort to elucidate it. Normal human nasopharyngeal epithelial cells and NPC cell lines were cultured. The expression levels of miR-302c-5p and HSP90AA1 were detected with quantitative real-time PCR. Western blotting was used to analyze levels of the HSP90AA1, protein kinase B (AKT), p-AKT, CD44 and SOX2 proteins. The interaction between miR-302c-5p and HSP90AA1 was detected using a luciferase reporter assay. The bicinchoninic acid assay was used to observe cisplatin resistance in NPC cells. Our records confirmed that the expression of miR-302c-5p was substantially reduced and HSP90AA1 was increased in NPC cells. Additionally, miR-302c-5p inhibited cisplatin resistance and the traits of stem cells in NPC. A luciferase assay confirmed that miR-302c-5p is bound to HSP90AA1. Overexpression of HSP90AA1 may reverse the effects of overexpressed miR-302c-5p and inhibit cisplatin resistance and stem cell traits of NPC. This study investigated whether miR-302c-5p inhibited the AKT pathway by regulating HSP90AA1 expression and altered the resistance of NPC cells to cisplatin and the traits of tumor stem cells, which has not yet been reported.

Type 1 and Type 2 Epstein-Barr viruses induce proliferation, and inhibit differentiation, in infected telomerase-immortalized normal oral keratinocytes

Differentiated epithelial cells are an important source of infectious EBV virions in human saliva, and latent Epstein-Barr virus (EBV) infection is strongly associated with the epithelial cell tumor, nasopharyngeal carcinoma (NPC). However, it has been difficult to model how EBV contributes to NPC, since EBV has not been shown to enhance proliferation of epithelial cells in monolayer culture in vitro and is not stably maintained in epithelial cells without antibiotic selection. In addition, although there are two major types of EBV (type 1 (T1) and type 2 (T2)), it is currently unknown whether T1 and T2 EBV behave differently in epithelial cells. Here we inserted a G418 resistance gene into the T2 EBV strain, AG876, allowing us to compare the phenotypes of T1 Akata virus versus T2 AG876 virus in a telomerase-immortalized normal oral keratinocyte cell line (NOKs) using a variety of different methods, including RNA-seq analysis, proliferation assays, immunoblot analyses, and air-liquid interface culture. We show that both T1 Akata virus infection and T2 AG876 virus infection of NOKs induce cellular proliferation, and inhibit spontaneous differentiation, in comparison to the uninfected cells when cells are grown without supplemental growth factors in monolayer culture. T1 EBV and T2 EBV also have a similar ability to induce epithelial-to-mesenchymal (EMT) transition and activate canonical and non-canonical NF-κB signaling in infected NOKs. In contrast to our recent results in EBV-infected lymphoblastoid cells (in which T2 EBV infection is much more lytic than T1 EBV infection), we find that NOKs infected with T1 and T2 EBV respond similarly to lytic inducing agents such as TPA treatment or differentiation. These results suggest that T1 and T2 EBV have similar phenotypes in infected epithelial cells, with both EBV types enhancing cellular proliferation and inhibiting differentiation when growth factors are limiting.

Exosomal HMGA2 protein from EBV-positive NPC cells destroys vascular endothelial barriers and induces endothelial-to-mesenchymal transition to promote metastasis

Increased vascular permeability facilitates metastasis. Cancer-secreted exosomes are emerging mediators of cancer-host crosstalk. Epstein-Barr virus (EBV), identified as the first human tumor-associated virus, plays a crucial role in metastatic tumors, especially in nasopharyngeal carcinoma (NPC). To date, whether and how exosomes from EBV-infected NPC cells affect vascular permeability remains unclear. Here, we show that exosomes from EBV-positive NPC cells, but not exosomes from EBV-negative NPC cells, destroy endothelial cell tight junction (TJ) proteins, which are natural barriers against metastasis, and promote endothelial-to-mesenchymal transition (EndMT) in endothelial cells. Proteomic analysis revealed that the level of HMGA2 protein was higher in exosomes derived from EBV-positive NPC cells compared with that in exosomes derived from EBV-negative NPC cells. Depletion of HMGA2 in exosomes derived from EBV-positive NPC cells attenuates endothelial cell dysfunction and tumor cell metastasis. In contrast, exosomes from HMGA2 overexpressing EBV-negative NPC cells promoted these processes. Furthermore, we showed that HMGA2 upregulates the expression of Snail, which contributes to TJ proteins reduction and EndMT in endothelial cells. Moreover, the level of HMGA2 in circulating exosomes is significantly higher in NPC patients with metastasis than in those without metastasis and healthy negative controls, and the level of HMGA2 in tumor cells is associated with TJ and EndMT protein expression in endothelial cells. Collectively, our findings suggest exosomal HMGA2 from EBV-positive NPC cells promotes tumor metastasis by targeting multiple endothelial TJ and promoting EndMT, which highlights secreted HMGA2 as a potential therapeutic target and a predictive marker for NPC metastasis.

Sanguinarine suppresses cell proliferation, migration and invasion in nasopharyngeal carcinoma inhibiting mTOR signaling

OBJECTIVE

To confirm the anti-NPC effect of sanguinarine (SA) through a series of wet experiments.

METHODS

NPC cell viability was determined by proliferation experiment. Cell clone formation experiment, cell scratch test, transwell migration and invasion experiment and flow cytometry-based cell apoptosis assay were further performed. In addition, Western blotting was performed to investigate the cell signaling pathway. All the relevant experimental data were statistically processed using SPSS 16.0 software.

RESULTS

The results showed that sanguinarine represented a time and dose dependent inhibition effects on NPC cell proliferation including the low differentiated CNE2 cells and high metastatic 5-8F cells, along with the cell cloning ability reduction. In addition, sanguinarine has a certain inhibitory effect on the invasion and migration of NPC cells. Mechanistically, sanguinarine displayed the anti-NPC effects mainly involved into the suppression of mTOR signaling and cell apoptosis, which is closely associated with the tumor growth and metastatic malignancy.

CONCLUSIONS

Collectively, we discover that sanguinarine is a new high-efficiency anti-NPC monomer of Chinese medicine, with a value for the follow-up pre-clinical research.

DPCPX induces Bim-dependent apoptosis in nasopharyngeal carcinoma cells

ADORA1 promotes tumor growth and development in multiple cancers. DPCPX (a selective adenosine A1 receptor antagonist), a specific ADORA1 antagonist, has shown antitumor effects in many cancer types. Nevertheless, the function of DPCPX in nasopharyngeal carcinoma (NPC) still remains to be unraveled. In this study, we investigated the functional role of DPCPX on NPC cells. We found that DPCPX promotes NPC cells growth inhibition. DPCPX induced Bim-dependent apoptosis in NPC cells irrespective of p53 status via the FoxO3a pathway following PI3K/AKT inhibition. Furthermore, DPCPX enhanced the antitumor effect of cisplatin, 5-FU and Paclitaxel in NPC. Xenograft experiment revealed that deficiency of Bim in vivo stalls apoptosis and antitumor activity of DPCPX. In conclusion, the PI3K/AKT/FoxO3a/Bim axis plays a critical role in the anticancer effects of DPCPX in NPC.

Pentagalloylglucose suppresses the growth and migration of human nasopharyngeal cancer cells via the GSK3β/β-catenin pathway in vitro and in vivo

BACKGROUND

Nasopharyngeal carcinoma (NPC) is a type of malignant squamous cell tumour originating from the nasopharynx epithelium. Pentagalloylglucose (PGG) is a natural polyphenolic compound that exerts anticancer effects in many types of tumours. However, the role and underlying mechanism of PGG in NPC cells have not been fully defined.

PURPOSE

This study aimed to investigate the anticancer activity of PGG as well as the potential mechanism in NPC cells.

METHODS

The effects of PGG on the proliferation, apoptosis and cell cycle distribution of CNE1 and CNE2 cells were assessed by MTT and flow cytometry assays. Cell migration was evaluated using wound healing and transwell assays. The expression of microtubule-associated protein 1 light chain 3 beta (LC3B) was observed by immunofluorescence staining. Western blotting was used to explore the levels of related proteins and signalling pathway components. Furthermore, the effects of PGG on NPC cell growth were analysed in a xenograft mouse model in vivo using cisplatin as a positive control.

RESULTS

PGG dose-dependently inhibited the proliferation of CNE1 and CNE2 cells. PGG regulated the cell cycle by altering p53, cyclin D1, CDK2, and cyclin E1 protein levels. PGG induced apoptosis and autophagy in NPC cells and elevated the Bax/Bcl-2 ratio and the protein levels of LC3B. Moreover, PGG decreased NPC cell migration by increasing E-cadherin and decreasing N-cadherin, vimentin and CD44 protein levels. Mechanistically, PGG treatment downregulated p-mTOR and β-catenin expression but upregulated p-p38 MAPK and p-GSK3β expression. In addition, PGG significantly inhibited NPC cell tumour growth and lung metastasis in vivo.

CONCLUSION

PGG may suppress cell proliferation, induce apoptosis and autophagy, and decrease the metastatic capacity of NPC cells through the p38 MAPK/mTOR and Wnt/β-catenin pathways. The present study provides evidence for PGG as a potential therapy for NPC.

Saucerneol attenuates nasopharyngeal carcinoma cells proliferation and metastasis through selectively targeting Grp94

BACKGROUND

Nasopharyngeal carcinoma (NPC) is highly prevalent in southern China. The remote metastasis of advanced NPC requires chemotherapeutic treatments to reduce the mortality. Our previous work revealed that saucerneol (SN) showed cytotoxicity against several nasopharyngeal carcinoma (NPC) cells. This work aims to investigate the effect of SN in NPC growth and exploring the mechanism of action.

STUDY DESIGN

Applying in vivo study, in vitro study and in silico study to indicate the mechanism of SN in inhibiting NPC growth.

METHODS

Saucerneol (SN) toxicity was measured with MTT assay. NPC proliferation was measured with EdU and colony formation assays, cell cycle was detected with flow cytometry. NPC migration and invasion were measured with scratch assay and matrigel transwell method. Further, human NPC xenograft tumor models were established in nude mice to evaluate the therapeutic efficacy of SN in vivo. Toxicological analysis was performed on H&E staining and IHC. Quantitative real-time PCR and Western blot analyses were used to evaluate the expression levels of key molecules in PI3K/AKT/mTOR, MAPK, NF-κB, and HIF-1α signal pathways. Target predicting was conducted using computational method, and target identification was carried out by ATPase assay and TSA.

RESULTS

SN, a potent NPC inhibitor that was previously isolated from Saururus chinensis in our lab, is proven to inhibit the proliferation and metastasis of HONE1 cell lines and inhibit the growth of human NPC xenografts in nude mice. Moreover, we further articulate the molecular mechanism of action for SN and, reveal that SN promotes the expression of cell cycle-dependent kinase inhibitory protein p21 Waf1/Cip1 through targeting Grp94 and then inhibiting PI3K/AKT signaling pathway as well as up-regulating p53 to disrupt the progression of HONE1 cells.

CONCLUSION

SN significantly inhibits NPC cells proliferation and metastasis in vitro and in vivo via selectively inhibit Grp94 and then blocking PI3K/AKT/mTOR/HIF-1α signaling pathway. This study firstly provides a novel selective Grp94 inhibitor as a NPC candidate.

DNTTIP1 promotes nasopharyngeal carcinoma metastasis via recruiting HDAC1 to DUSP2 promoter and activating ERK signaling pathway

Background

Distant metastasis remains the leading cause of treatment failure in patients with nasopharyngeal carcinoma (NPC), making it critical to identify efficient therapeutic targets for metastatic NPC. Previous studies have demonstrated that deoxynucleotidyltransferase terminal-interacting protein 1 (DNTTIP1) is associated with the development of various types of cancer. However, its role and mechanism in NPC have not been explored.

Methods

RNA-seq profiling was performed for three pairs of NPC and normal nasopharynx tissues. DNTTIP1 expression in NPC specimens was detected by immunohistochemistry. In vitro and in vivo assays were used to investigate the function of DNTTIP1. The molecular mechanism was determined using RT-qPCR, western blotting, RNA-seq, luciferase reporter assays, ChIP assays, and co-IP assays.

Findings

DNTTIP1 was found to be significantly upregulated in NPC tissues. Furthermore, DNTTIP1 promoted NPC growth and metastasis in vitro and in vivo. Upregulation of DNTTIP1 in NPC indicated poor clinical outcomes. Mechanistically, DNTTIP1 suppressed DUSP2 gene expression via recruiting HDAC1 to its promoter and maintaining a deacetylated state of histone H3K27. The downregulation of DUSP2 resulted in aberrant activation of the ERK signaling and elevated MMP2 levels, promoting NPC metastasis. Chidamide, an HDAC inhibitor, was shown to suppress NPC metastasis by regulating the DNTTIP1/HDAC1-DUSP2 axis.

Interpretation

Our findings demonstrate that DNTTIP1 not only regulates NPC metastasis but also independently predicts NPC prognosis. Furthermore, targeting DNTTIP1/HDAC1 by Chidamide may benefit NPC patients with metastasis.

Funding

This work was supported by the National Natural Science Foundation of China (No. 81872464, 82073243).

[Nasopharyngeal carcinoma with non-squamous immunophenotype: a clinicopathological analysis of 23 cases]

Objective: To investigate the pathological subtypes and clinicopathological characteristics of the non-squamous immunophenotype nasopharyngeal carcinoma (NSNPC). Methods: The clinicopathological features of the non-squamous immunophenotype nasopharyngeal carcinoma diagnosed between 2011 and 2019 at the First Affiliated Hospital of Zhengzhou University were analyzed using hematoxylin and eosin staining, immunohistochemistry, in situ hybridization, transmission electron microscopy and PCR gene rearrangement. Follow-up data were also collected. Results: There were 14 males and 9 females with a median age of 46 years (ranging from 16 to 76 years) with an average age of 45 years. Microscopically, patterns were similar to the classic nasopharyngeal carcinoma. Immunohistochemistry showed that most NSNPC cases expressed low molecular weight keratin (CK8/18, CK8 and CKL) and expressed pathway proteins in a low level (EGFR, PI3K, p-AKT and p-mTOR), which had significant difference from classic nasopharyngeal carcinoma group (P<0.05). Other proteins including CK5/6, CKpan, CK7, Syn, CD56, CgA, SOX-10, AKT, mTOR, Notch, STAT3 and p-STAT3 showed no statistical difference between the two groups. Pathogen detection showed that EBER was positive (18/23, 78.3%) and HPV positive(2/23, 8.7%)which were HPV35 and HPV38. The cancer suppressor gene BLU was highly expressed in NSNPC; RASSF1 and Rbms3 were less expressed in NSNPC, in line with classic NPC. As a whole, NSNPC was characterized by ultrastructures of low-differentiated squamous cell carcinoma. Compared with classic nasopharyngeal carcinoma, NSNPC had a lower recurrence rate and earlier clinical stage(P<0.05),but there was no significant correlation with age, sex, distant metastasis and death (P>0.05). Conclusions: The histological morphology, etiology and gene changes of NSNPC are similar to those of classical nasopharyngeal carcinoma and ultrastructural findings show that NSNPC still belongs to undifferentiated type in non-keratinized squamous cell carcinoma. The malignant degree of NSNPC is low and the prognosis is good.

Cytokeratin 13 promotes radiotherapy sensitivity of nasopharyngeal carcinoma by downregulating the MEK/ERK pathway

BACKGROUND

Radiation therapy is the first treatment choice for nasopharyngeal carcinoma (NPC), while radiation resistance and recurrence have become the primary factors and are associated with poor prognosis in the clinical treatment of NPC patients. The purpose of the present study was to explore the sensitivity and molecular basis of cytokeratin 13 (CK13) that regulates NPC radiotherapy.

METHODS

HNE-3 or C666-1 cell line was used for overexpression and knockdown tests. Under radiotherapy conditions, CCK-8 assay, clone formation assay, and flow cytometry analyzed the effects of CK13 overexpression on cell proliferation, apoptosis, and cell cycle, respectively. In addition, Western blotting detected CK13-mediated downregulation of cell cycle-related genes. The mouse subcutaneous tumor-bearing experiment identified the effects of CK13 overexpression on the treatment of NPC in vivo. Further, Western blotting, CCK-8 assay, and flow cytometry investigated whether the CK13-mediated cell apoptosis involves the MEK/ERK signaling pathway.

RESULTS

Overexpression of CK13 significantly inhibited the survival of HNE-3 cells under radiotherapy in vitro and in vivo, and there was a substantial decrease in cyclin-dependent kinase 4 and 6 (CDK4/6) levels promoting the cell percentage number in the G2/M phase and, subsequently, the ratio of the apoptotic cells. In contrast, the knockdown of CK13 showed the opposite partial regulatory effect. Interestingly, CK13 overexpression also showed a reduction in the survival of C666-1 cells and an increased ratio of the apoptotic cells under radiotherapy treatment. Furthermore, higher levels of CK13 downregulated the MEK/ERK signaling pathway, resulting in decreased HNE-3 cell proliferation and increased apoptosis. However, ERK activators were able to rescue the process partially.

CONCLUSIONS

Together, these results showed that CK13 promoted the radiosensitivity of NPC cells by downregulating the MEK/ERK signaling pathway. Thus, targeting CK13 provided insights into the treatment of NPC radiotherapy.

Timosaponin AIII Suppresses RAP1 Signaling Pathway to Enhance the Inhibitory Effect of Paclitaxel on Nasopharyngeal Carcinoma

Although PTX has been identified as an effective drug for nasopharyngeal carcinoma (NPC) therapy, it has serious side effects in the human body. Previous studies have shown that timosaponin AIII (TSAIII) can inhibit the malignant progression of NPC cells. This study investigated the active mechanism of the combination of TSAIII and paclitaxel (PTX) on NPC. Cellular viability, apoptosis, apoptotic factors, and RAP1 signaling regulators were detected in the PNC cells (CNE-1 and HNE-2) and the subcutaneous CNE-1 transplanted nude mice treated with PTX or/and TSAIII. The results showed that TSAIII notably strengthened the inhibitory effect of PTX on the proliferation of NPC cells CNE-1 and HNE-2; upregulated the expression of Bax B-cell lymphoma 2 (Bcl-2)/Bcl-xL-associated death promoter (Bad), and Ras-associated protein1 (RAP1) GTPase activating protein (Rap1GAP); inhibited the level of Bcl-2, RAP1, and Ras guanine nucleotide releasing protein (RasGRP2); and significantly enhanced the promoting effect of PTX on apoptosis in the CNE-1 and HNE-2 cells. Besides, TSAIII strengthened the inhibitory effect of PTX on xenograft tumor in nude mice without adverse reactions. In conclusion, the combination administration of TSAIII and PTX had a significantly therapeutic effect on NPC and avoided the PTX's side effects, which may have acted as a new direction for the study of therapeutic approaches for NPC clinically.

Prognostic value of EGFR and p-EGFR in nasopharyngeal carcinoma: A systematic review and meta-analysis

PURPOSE

To evaluate the prognostic effect and clinical significance of epidermal growth factor receptor and its phosphorlated form (EGFR/p-EGFR) in nasopharyngeal carcinoma.

METHODS

A systematic review and meta-analysis was designed. We visited PubMed, Embase, China National Knowledge Infrastructure Database, Database of Chinese sci-tech periodicals, WanFang Database, and China Biology Medicine disc to search for Chinese and English publications of prospective studies and retrospective studies investigating the association of EGFR/p-EGFR and nasopharyngeal carcinoma prognosis from inception to April 2021. The inclusion criteria were that the samples should be pathologically confirmed as nasopharyngeal carcinoma and the expression of EGFR/p-EGFR should be detected via immunohistochemistry; the study should analyze the prognostic significance of EGFR/p-EGFR in nasopharyngeal carcinoma; hazard ratio (HR) and 95% confidence interval (CI) should be reported in the study or could be derived from survival curves; and the outcomes of the study should include overall survival (OS), disease-free survival (DFS), progression-free survival (PFS), and distant metastasis-free survival (DMFS).

RESULTS

A total of 18 studies evaluating 1451 samples were included. For studies that reported OS as an outcome, EGFR overexpression indicated worse OS of nasopharyngeal carcinoma patients. The heterogeneity between studies was high (I2 = 91%, P < .01), and a random-effect model was used to combine the effect size (HR = 1.71, 95% CI [1.21, 2.41], P < .01). Further sensitivity analysis and prespecified subgroup analysis were performed to detect the source of heterogeneity, and the results showed that the heterogeneity could not be eliminated. Publication bias assessed by funnel plots and Begg test and Egger test was low (Begg test: P = .846 and Egger test: P = .074). p-EGFR was not correlated with the OS of nasopharyngeal carcinoma patients (HR = 1.01, 95% CI [0.88, 1.15], P = .92). For studies that reported DFS, EGFR overexpression was associated with worse DFS in patients with nasopharyngeal carcinoma (HR = 2.53, 95% CI [1.84, 3.47], P < .01). For studies that reported PFS, EGFR overexpression was not correlated with the PFS of nasopharyngeal carcinoma patients (HR = 1.86, 95% CI [0.90, 3.82], P = .09). For studies that reported DMFS, EGFR overexpression was not correlated with the DMFS of nasopharyngeal carcinoma patients, and high heterogeneity between studies was detected (I2 = 97%, P < .01). A random-effect model was used to combine the effect size (HR = 1.80, 95% CI [0.56, 5.76], P = .32). A sensitivity analysis was conducted. Publication bias was detected to be low (Begg test: P = .817 and Egger test: P = .954). There was no correlation between p-EGFR overexpression and DMFS in patients with nasopharyngeal carcinoma (HR = 1.20, 95% CI [0.95, 1.52], P = .12).

CONCLUSION

In nasopharyngeal carcinoma patients, EGFR overexpression could be used as a biomarker that predicts poor OS and DFS, but not a prognostic biomarker for PFS and DMFS. The overexpression of p-EGFR was not shown to be associated with the prognosis of nasopharyngeal carcinoma patients and could not be used as a prognostic biomarker.

ETHICS AND DISSEMINATION

This study was registered on the International Platform of Registered Systematic Review and Meta-analysis Protocols (INPLASY), and reported as stated by the Preferred Reporting Items for Systematic reviews and Meta-Analyses. Neither ethical approval nor informed consent was required since this study was conducted based on previous publications.

INPLASY REGISTRATION NUMBER

INPLASY 202150010.

IGF2BP3 promotes cell metastasis and is associated with poor patient survival in nasopharyngeal carcinoma

Metastasis contributes to treatment failure in nasopharyngeal carcinoma (NPC) patients. Our study aimed at elucidating the role of insulin-like growth factor 2 mRNA binding protein 3 (IGF2BP3) in NPC metastasis and the underlying mechanism involved. IGF2BP3 expression in NPC was determined by bioinformatics, quantitative polymerase chain reaction and immunohistochemistry analyses. The biological function of IGF2BP3 was investigated by using in vitro and in vivo studies. In this study, IGF2BP3 mRNA and protein levels were elevated in NPC tissues. In addition, IGF2BP3 exerted an oncogenic role by promoting epithelial-mesenchymal transition (EMT), thereby inducing NPC cell migration and invasion. Further studies revealed that IGF2BP3 regulated the expression of key regulators of EMT by activating AKT/mTOR signalling, thus stimulating NPC cell migration and invasion. Remarkably, targeting IGF2BP3 delayed NPC metastasis through attenuating p-AKT and vimentin expression and inducing E-cadherin expression in vivo. Moreover, IGF2BP3 protein levels positively correlated with distant metastasis after initial treatment. Importantly, IGF2BP3 expression served as an independent prognostic factor in predicting the overall survival and distant metastasis-free survival of NPC patients. This work identifies IGF2BP3 as a novel prognostic marker and a new target for NPC treatment.

Identification of the alpha linolenic acid metabolism-related signature associated with prognosis and the immune microenvironment in nasopharyngeal carcinoma

BACKGROUND

Tumor metabolism is important for cancer progression. Nevertheless, the role of the metabolism pathway and related molecules in nasopharyngeal carcinoma (NPC) is limited.

METHODS

Open-accessed data was downloaded from The Cancer Genome Atlas database. All the analysis was performed using the R software and the package in R environments.

RESULTS

In our study, we firstly explored the role of 21 metabolism-related pathways in NPC patients. We found that the steroid biosynthesis and biosynthesis of unsaturated fatty acids were risk factors, while the alpha linolenic acid metabolism was a protective factor. Then, the alpha linolenic acid metabolism aroused our interest. A total of 128 differentially expressed genes (DEGs) were identified, including 71 downregulated and 57 upregulated genes identified between high and low alpha linolenic acid metabolism level. Based on these DEGs, we constructed a prognosis model including DEFB4B, FOXL2NB, MDGA2, RTL1, SLURP2, TMEM151B and TSPAN19, which showed great prediction efficiency in both training and validation cohorts. Clinical correlation analysis showed that high-risk patients might have worse clinical pathology parameters. Pathway enrichment analysis showed that riskscore was positively correlated with angiogenesis, DNA repair, G2/M checkpoints, IL6/JAK/STAT3 signaling, KRAS signaling up, WNT beta-catenin signaling, PI3K/AKT/mTOR signaling, yet positively correlated with inflammatory response, xenobiotic metabolism, TNF-α signaling via NFKB and interferon-gamma response. Immune infiltration analysis showed that the riskscore was positively correlated with the M2 and M0 macrophages, but negatively correlated with neutrophils, plasma cells, follicular helper T cells and resting dendritic cells Moreover, we found that the low-risk patients might be more sensitive to immunotherapy and lapatinib.

CONCLUSIONS

In all, our study identified the genes associated with alpha linolenic acid metabolism and constructed an effective prognosis model which could robustly predict NPC patients prognosis.

Forkhead Box Protein M1 Promotes Nasopharyngeal Carcinoma Cell Tumorigenesis Possibly via the Wnt/β-Catenin Signaling Pathway

BACKGROUND Forkhead box protein M1 (FoxM1) is an important transcription factor involved in the development and progression of various malignancies. However, its role in nasopharyngeal carcinoma (NPC) remains largely unknown. This study aimed to assess the effect of FoxM1 on NPC cell tumorigenesis as well as the underlying mechanism. MATERIAL AND METHODS NPC cell lines CNE-1 and CNE-2 were treated with vehicle and FoxM1 inhibitor thiostrepton or transfected with small interfering RNA. CCK-8 assay, flow cytometric assay, and Hoechst 33258 staining were performed to assess the viability, apoptosis and nuclear morphological impairment, and cell cycle, respectively. The expression of apoptosis-related caspase-3 and caspase-9 was detected by western blot analysis The tumor growth in the mouse xenograft model of NPC treated with thiostrepton or control was assessed. The expression of Wnt/ß-catenin signaling proteins p27, FoxM1, S phase kinase-associated protein 2 (SKP2), and Cyclin D1 were determined both in cells and xenograft tissues by western blot analysis. RESULTS Inhibition of FoxM1 by thiostrepton significantly suppressed NPC cell viability, induced apoptosis, increased cell cycle arrest, impaired nuclear morphology, and reduced NPC cell-derived tumor xenograft growth. Mechanistically, inhibition or knockdown of FoxM1 inactivated the Wnt/ß-catenin signaling pathway, as demonstrated by altered expression of Wnt/ß-catenin signaling-related genes, including p27, SKP2, and cyclin D1, in both NPC cells and xenograft tissues. CONCLUSIONS We identified FoxM1 as a novel regulator of NPC cell tumorigenesis in vitro and in vivo. Targeting FoxM1 could be a promising therapeutic strategy against NPC.

Efficacy, safety, and biomarker analysis of Camrelizumab in Previously Treated Recurrent or Metastatic Nasopharyngeal Carcinoma (CAPTAIN study)

BACKGROUND

This study aimed to evaluate the antitumor activity of camrelizumab, an antiprogrammed cell death-1 antibody, in pretreated recurrent or metastatic nasopharyngeal carcinoma (NPC) and to explore predictive biomarkers.

METHODS

Patients with recurrent (not amenable to locally curative treatment) or metastatic NPC who had failed at least two lines of chemotherapy were eligible to receive camrelizumab (200 mg intravenously every 2 weeks) for 2 years or until disease progression, intolerable adverse events, withdrawal of consents, or investigator decision. The primary endpoint was objective response rate (ORR) assessed by an independent review committee (IRC). Programmed cell death-ligand 1 (PD-L1) expression was assessed by immunohistochemistry. Other immune-related biomarkers including major histocompatibility complex class I and major histocompatibility complex class II (MHC-II) were assessed by multiplex immunofluorescence staining.

RESULTS

Between August 14, 2018, and December 30, 2019, a total of 156 patients were enrolled. The IRC-assessed ORR was 28.2% (95% CI 21.3% to 36.0%). The median progression-free survival was 3.7 months (95% CI 2.0 to 4.1) per IRC, and the median overall survival was 17.4 months (95% CI 15.2 to 21.9). The ORRs were 35.2% (95% CI 25.3% to 46.1%) vs 19.4% (95% CI 10.4% to 31.4%) in patients with tumor PD-L1 expression of ≥10% and<10%, respectively. Patients with durable clinical benefit (DCB), which was defined as complete response, partial response or stable disease of ≥18 weeks, had higher density of MHC-II+ cell in stroma than patients without DCB (median 868.1 (IQR 413.4-2854.0) cells/mm2 vs median 552.4 (IQR 258.4 to 1242.1) cells/mm2). MHC-II+ cell density did not correlate with PD-L1 expression, and a composite of high stromal MHC-II+ cell density and tumor PD-L1 expression further enriched patients who could benefit from camrelizumab.

CONCLUSIONS

Camrelizumab had clinically meaningful antitumor activity in patients with recurrent or metastatic NPC. The composition of both MHC-II+ cell density and PD-L1 expression could result in better patient selection.

NAP1L1 targeting suppresses the proliferation of nasopharyngeal carcinoma

Nucleosome assembly protein 1-like 1 (NAP1L1) is significantly involved in the development of various cancers. However, its role in the molecular mechanism of nasopharyngeal carcinoma (NPC) remains undetermined. In this study, we detected the upregulated expression of NAP1L1 mRNA and protein levels by quantitative polymerase chain reaction and Western blot analysis in NPC cell lines. Results of the immunohistochemistry analysis of NPC tissue biopsies showed that upregulated NAP1L1 protein expression promoted NPC progression and negatively correlated with poor prognosis in NPC patients. Suppression of NAP1L1 expression by small interfering RNA (siRNA) or small hairpin RNA (shRNA) methods significantly decreased cell proliferation in vivo and in vitro. Mechanism analysis revealed that the regulation of cell growth was enriched by Gene Set Enrichment Analysis based on RNA sequencing data. Cell cycle-induced genes CCND1 and E2F1 were downregulated in NAP1L1 knockdown NPC cells. Reduced NAP1L1 suppressed the recruitment of hepatoma-derived growth factor (HDGF) and decreased its expression. Knockdown of HDGF reduced the expression of c-JUN, a key oncogenic transcription factor that can induce the expression of cyclin D1 (CCND1), reducing cell cycle progression and suppressing cell growth in NPC. Transfecting HDGF or c-JUN could reverse the growth-suppressive effects in NAP1L1-downregulated NPC cells. The data obtained in this study suggest that NAP1L1 acts as a potential oncogene by activating HDGF/c-JUN/CCND1 signaling in NPC.

ΔNp63α promotes Epstein-Barr virus latency in undifferentiated epithelial cells

Epstein-Barr virus (EBV) is a human herpesvirus that causes infectious mononucleosis and contributes to both B-cell and epithelial-cell malignancies. EBV-infected epithelial cell tumors, including nasopharyngeal carcinoma (NPC), are largely composed of latently infected cells, but the mechanism(s) maintaining viral latency are poorly understood. Expression of the EBV BZLF1 (Z) and BRLF1 (R) encoded immediate-early (IE) proteins induces lytic infection, and these IE proteins activate each other's promoters. ΔNp63α (a p53 family member) is required for proliferation and survival of basal epithelial cells and is over-expressed in NPC tumors. Here we show that ΔNp63α promotes EBV latency by inhibiting activation of the BZLF1 IE promoter (Zp). Furthermore, we find that another p63 gene splice variant, TAp63α, which is expressed in some Burkitt and diffuse large B cell lymphomas, also represses EBV lytic reactivation. We demonstrate that ΔNp63α inhibits the Z promoter indirectly by preventing the ability of other transcription factors, including the viral IE R protein and the cellular KLF4 protein, to activate Zp. Mechanistically, we show that ΔNp63α promotes viral latency in undifferentiated epithelial cells both by enhancing expression of a known Zp repressor protein, c-myc, and by decreasing cellular p38 kinase activity. Furthermore, we find that the ability of cis-platinum chemotherapy to degrade ΔNp63α contributes to the lytic-inducing effect of this agent in EBV-infected epithelial cells. Together these findings demonstrate that the loss of ΔNp63α expression, in conjunction with enhanced expression of differentiation-dependent transcription factors such as BLIMP1 and KLF4, induces lytic EBV reactivation during normal epithelial cell differentiation. Conversely, expression of ΔNp63α in undifferentiated nasopharyngeal carcinoma cells and TAp63α in Burkitt lymphoma promotes EBV latency in these malignancies.

Epstein-Barr Virus-Encoded Circular RNA CircBART2.2 Promotes Immune Escape of Nasopharyngeal Carcinoma by Regulating PD-L1

Epstein-Barr virus (EBV) infection is an established cause of nasopharyngeal carcinoma (NPC) and is involved in a variety of malignant phenotypes, including tumor immune escape. EBV can encode a variety of circular RNAs (circRNA), however, little is known regarding the biological functions of these circRNAs in NPC. In this study, EBV-encoded circBART2.2 was found to be highly expressed in NPC where it upregulated PD-L1 expression and inhibited T-cell function in vitro and in vivo. circBART2.2 promoted transcription of PD-L1 by binding the helicase domain of RIG-I and activating transcription factors IRF3 and NF-κB, resulting in tumor immune escape. These results elucidate the biological function of circBART2.2, explain a novel mechanism of immune escape caused by EBV infection, and provide a new immunotherapy target for treating NPC. SIGNIFICANCE: This work demonstrates that circBART2.2 binding to RIG-I is essential for the regulation of PD-L1 and subsequent immune escape in nasopharyngeal carcinoma.

FLAME: long-read bioinformatics tool for comprehensive spliceome characterization

Comprehensive characterization of differentially spliced RNA transcripts with nanopore sequencing is limited by bioinformatics tools that are reliant on existing annotations. We have developed FLAME, a bioinformatics pipeline for alternative splicing analysis of gene-specific or transcriptome-wide long-read sequencing data. FLAME is a Python-based tool aimed at providing comprehensible quantification of full-length splice variants, reliable de novo recognition of splice sites and exons, and representation of consecutive exon connectivity in the form of a weighted adjacency matrix. Notably, this workflow circumvents issues related to inadequate reference annotations and allows for incorporation of short-read sequencing data to improve the confidence of nanopore sequencing reads. In this study, the Epstein-Barr virus long noncoding RNA RPMS1 was used to demonstrate the utility of the pipeline. RPMS1 is ubiquitously expressed in Epstein-Barr virus associated cancer and known to undergo ample differential splicing. To fully resolve the RPMS1 spliceome, we combined gene-specific nanopore sequencing reads from a primary gastric adenocarcinoma and a nasopharyngeal carcinoma cell line with matched publicly available short-read sequencing data sets. All previously reported splice variants, including putative ORFs, were detected using FLAME. In addition, 32 novel exons, including two intron retentions and a cassette exon, were discovered within the RPMS1 gene.

Radiotherapy Combined with PD-1 Inhibition Increases NK Cell Cytotoxicity towards Nasopharyngeal Carcinoma Cells

BACKGROUND

Nasopharyngeal carcinoma (NPC) in endemic regions and younger patients is characterized by a prominent lymphomononuclear infiltration. Radiation is the principal therapeutic modality for patients with NPC. Recent data suggest that the efficacy of radiotherapy in various cancers can be augmented when combined with immune checkpoint blockade. Here, we investigate the effect of radiotherapy on the killing of NPC cells by Natural Killer (NK) cells.

METHODS

NPC cell lines and a patient-derived xenograft were exposed to NK cells in the context of radiotherapy. Cytotoxicity was measured using the calcein-release assay. The contribution of the PD-L1/PD-1 checkpoint and signaling pathways to killing were analyzed using specific inhibitors.

RESULTS

Radiotherapy sensitized NPC cells to NK cell killing and upregulated expression of PD-1 ligand (PD-L1) in NPC cells and PD-1 receptor (PD-1) in NK cells. Blocking of the PD-L1/PD-1 checkpoint further increased the killing of NPC cells by NK cells in the context of radiotherapy.

CONCLUSION

Radiation boosts the killing of NPC cells by NK cells. Killing can be further augmented by blockade of the PD-L1/PD-1 checkpoint. The combination of radiotherapy with PD-L1/PD-1 checkpoint blockade could therefore increase the efficacy of radiotherapy in NPC tumors.

Circular RNA circRNF13 inhibits proliferation and metastasis of nasopharyngeal carcinoma via SUMO2

BACKGROUND

Circular RNAs (circRNAs) are widely expressed in human cells and are closely associated with cancer development. However, they have rarely been investigated in the context of nasopharyngeal carcinoma (NPC).

METHODS

We screened a new circRNA, circRNF13, in NPC cells using next-generation sequencing of mRNA. Reverse transcription polymerase chain reaction and RNA fluorescence in situ hybridization were used to detect circRNF13 expression in 12 non-tumor nasopharyngeal epithelial (NPE) tissues and 36 NPC samples. Cell proliferation was detected using MTT and flow cytometry assays, and colony formation capability was detected using colony formation assays. Cell migration and invasion were analyzed using wound-healing and Transwell assays, respectively. Cell glycolysis was analyzed using the Seahorse glycolytic stress test. Glucose transporter type 1 (GLUT1) ubiquitination and SUMOylation modifications were analyzed using co-immunoprecipitation and western blotting. CircRNF13 and Small Ubiquitin-like Modifier 2 (SUMO2) interactions were analyzed using RNA pull-down and luciferase reporter assays. Finally, to test whether circRNF13 inhibited NPC proliferation and metastasis in vivo, we used a xenograft nude mouse model generated by means of subcutaneous or tail vein injection.

RESULTS

We found that circRNF13 was stably expressed at low levels in NPC clinical tissues and NPC cells. In vitro and in vivo experiments showed that circRNF13 inhibited NPC proliferation and metastasis. Moreover, circRNF13 activated the SUMO2 protein by binding to the 3'- Untranslated Region (3'-UTR) of the SUMO2 gene and prolonging the half-life of SUMO2 mRNA. Upregulation of SUMO2 promotes GLUT1 degradation through SUMOylation and ubiquitination of GLUT1, which regulates the AMPK-mTOR pathway by inhibiting glycolysis, ultimately resulting in the proliferation and metastasis of NPC.

CONCLUSIONS

Our results revealed that a novel circRNF13 plays an important role in the development of NPC through the circRNF13-SUMO2-GLUT1 axis. This study implies that circRNF13 mediates glycolysis in NPC by binding to SUMO2 and provides an important theoretical basis for further elucidating the pathogenesis of NPC and targeted therapy.

Effect of miR-25 on Proliferation of Nasopharyngeal Carcinoma Cells through Wnt/β-Catenin Signaling Pathway

OBJECTIVE

To investigate the biological role and potential mechanism of miR-25 in nasopharyngeal carcinoma.

METHODS

The expression of miR-25 in nasopharyngeal carcinoma cell lines was detected by qRT-PCR. The effect of inhibition of miR-25 expression on the proliferative activity of nasopharyngeal carcinoma cell line HONE-1 was examined by CCK-8 method. Flow cytometry was used to detect the effect of miR-25 expression inhibition on the apoptosis rate of nasopharyngeal carcinoma cell line HONE-1. The miRNA target gene prediction site TargetScan predicts the target protein action site of miR-124 and verifies whether miR-25 interacts with the target by luciferase activity assay, qPCR, and Western experiments. The miR-25 inhibitor and target egg gene expression plasmids were cotransfected into HONE-1 cells for rescue experiments to investigate whether miR-25 inhibits proliferation of nasopharyngeal carcinoma cells by target genes. At the same time, qRT-PCR was used to detect the mRNA expression levels of Wnt/β-catenin pathway key proteins TCF4, c-Myc, and Cyclin D1 in different transfected cells.

RESULTS

miR-25 expression was upregulated in nasopharyngeal carcinoma cell lines. Functional studies showed that inhibition of miR-25 expression significantly inhibited the proliferation of nasopharyngeal carcinoma cell line HONE-1 (p < 0.05). Inhibition of miR-25 expression by flow cytometry significantly promoted apoptosis (p < 0.05). Detection of dual luciferase activity indicated that DKK3 is a direct target site for miR-25. Western blots showed that inhibition of miR-25 significantly upregulated DKK3 mRNA and protein levels. Supplementation with DKK3 significantly attenuated the inhibitory effect of miR-25 on the proliferation of nasopharyngeal carcinoma cell line HONE-1 (p < 0.05). qRT-PCR found that mRNA levels of TCF4, c-Myc, and Cyclin D1 were significantly upregulated in miR-25-transfected cells compared to control transfection. QRT PCR showed that the mRNA and protein levels of Tcf4, c-myc, and Cyclin D1 were significantly upregulated in miR-25 overexpression-transfected cells.

CONCLUSION

Inhibition of miR-25 expression promotes DKK3 gene expression, and inactivation of Wnt/β-catenin signaling pathway inhibits proliferation and promotes apoptosis of nasopharyngeal carcinoma cells.