The biology and function of extracellular vesicles in nasopharyngeal carcinoma (Review).

Extracellular vesicles are a heterogeneous group of membrane-enclosed vesicles, which play an important role in intercellular communication. Increasing number of studies have shown that tumor-derived extracellular vesicles might be involved in the transfer of oncogenic cargo (proteins, lipids, messenger RNA, microRNA, non-coding RNAs and DNA) through which cancer cells could shape the tumor microenvironment and influence tumor progression. Nasopharyngeal carcinoma-derived extracellular vesicles have also reported to facilitate tumor proliferation, metastasis and immune escape. Moreover, nasopharyngeal carcinoma-derived extracellular vesicles might serve as biomarkers for early diagnosis and therapeutic targets. The present review provides information on the biological and clinical significance of extracellular vesicles in tumors, especially in nasopharyngeal carcinoma.

Oncocitoma nasofaríngeo como causa de disfunción tubárica / Nasopharyngeal oncocytoma as a cause of Eustachian tube dysfunction

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Puquitinib mesylate (XC-302) induces autophagy via inhibiting the PI3K/AKT/mTOR signaling pathway in nasopharyngeal cancer cells.

There are numerous studies that demonstrate the anti-neoplastic activity of phosphatidylinositol 3-kinase (PI3K) inhibitors and the mechanisms of inducing autophagy in cancer cells. The new anticancer drug puquitinib mesylate (XC-302) is a molecular-targeted drug, which suppresses the activity of PI3K directly. However, it remains unclear whether XC­302 can develop an antitumor effect by inducing autophagy in nasopharyngeal cancer cells. The MTT assay was used to study the anti-proliferative effects of XC-302. Subsequently, autophagy was determined by monodansylcadaverine (MDC) staining, punctate localization of green fluorescent protein (GFP)-light chain 3 (LC3), LC3 protein blotting and electron microscopy. The expression levels of beclin 1, p62, protein kinase B (AKT), phospho (p)­AKT, mechanistic target of rapamycin (mTOR) and p­mTOR in XC-302­induced autophagy were detected. Autophagy inhibition was assayed by 3-methyladenine (3­MA) or small interfering RNA (siRNA) silencing of beclin 1. XC-302 inhibited the viability of CNE­2 in a dose-dependent manner and the IC50 of 72 h was 5.2 µmol/l. After cells were exposed to XC-302 for 24 h, MDC-labeled autophagolysosomes were evident in CNE-2 cells by fluorescence microscope. Autophagosomes and autolysosomes were identified by transmission electron microscopy. Following transfection with GFP­LC3, XC-302 induced a significant accumulation of GFP­LC3, as monitored by a confocal microscope, which was reduced by 3-MA. XC-302 induced the formation of LC3­II, increased beclin 1 levels and decreased the expression of p62. Additionally, the expression levels of p­AKT and p­mTOR were reduced with the elevation of XC-302. Knockdown of beclin 1 with siRNA or co-treatment with 3-MA enhanced significantly the survival of CNE-2 and promoted the ability of clone formation. XC-302 also induced apoptosis in CNE-2, and when autophagy was inhibited by 3-MA, the apoptosis rate was decreased. The present data provides the evidence that XC-302 can induce autophagy in CNE-2, which promotes the program of cell death and inhibits the PI3K/AKT/mTOR signaling pathway. Furthermore, XC-302 also promoted apoptosis in CNE-2 cells, which could be reduced when autophagy was suppressed, meaning that autophagy may interact with apoptosis to induce cell death.

TNFα antagonization alters NOS2 dependent nasopharyngeal carcinoma tumor growth.

Tumor necrosis factor (TNFα) is a pro-inflammatory cytokine which mediates via nitric oxide (NO) several carcinogenic processes. Increasing evidences suggest that NO promotes inflammation induced growth of nasopharyngeal carcinoma (NPC). In patients, TNFα synthesis associates with poor survival. To explore the effect of the cytokine on NO production and NOS2 dependent NPC growth, NO2(-) (nitrite) producing cells in patients were analyzed in vitro. We observed that patients' monocytes/macrophages (Mo/Ma) and primary tumor biopsies synthesized significant amounts of NO2(-). Interestingly, tumor explants derived NO2(-) levels were more important in elderly patients in comparison with juveniles. Endogenous TNFα neutralization with an anti-TNFα monoclonal antibody (mAb) successfully inhibited NO2(-) synthesis by blood mononuclear cells and tumor explants. Recombinant TNFα (rTNFα) enhanced NO2(-) synthesis and C666-1 NPC cell proliferation. NOS2 selective inhibition (1400W) and TNFα antagonization with an anti-TNFα mAb potently inhibited rTNFα induced C666-1 proliferation and NO2(-) production. Importantly, primary tumors treated with the anti-TNFα mAb also displayed reduced proliferation index (Ki67). Altogether, our results define monocytes/macrophages and the primary tumor as major sources of circulating NO2(-) in NPC patients and support the idea that antibody dependent inhibition of the TNFα/NOS2 pathway may alter NPC tumor growth.

Nasopharyngeal cylindrical cell papilloma.

INTRODUCTION: Cylindrical cell papillomas are rare tumours which usually arise in the sinonasal region. CASE REPORT: We report a case of a nasopharyngeal cylindrical cell papilloma in a 56-year-old man who presented with a four-month history of right-sided hearing loss, otalgia, vertigo and tinnitus. Investigation revealed a soft, nodular lesion obstructing the pharyngeal opening of the right eustachian tube; this was treated by wide endoscopic excision. CONCLUSION: Cylindrical cell papilloma is a possible cause of eustachian tube obstruction in adults. Effective treatment of these lesions usually requires wide endoscopic excision, in order not to miss coexistent carcinoma.

An inherited mitochondrial DNA disruptive mutation shifts to homoplasmy in oncocytic tumor cells.

A disruptive frameshift mtDNA mutation affecting the ND5 subunit of complex I is present in homoplasmy in a nasopharyngeal oncocytic tumor and inherited as a heteroplasmic germline mutation recurring in two of the patient's siblings. Homoplasmic ND5 mutation in the tumor correlates with lack of the ND6 subunit, suggesting complex I disassembly. A few oncocytic areas, expressing ND6 and heteroplasmic for the ND5 mutation, harbor a de novo homoplasmic ND1 mutation. Since shift to homoplasmy of ND1 and ND5 mutations occurs exclusively in tumor cells, we conclude that complex I mutations may have a selective advantage and accompany oncocytic transformation.

[Study on the apoptosis of nasopharyngeal carcinoma cell line administrated with Sarcandra glabra extracts in vivo and its mechanism].

OBJECTIVE: To evaluate the effect of Sarcandra glabra extracts on anti-tumor and apoptosis of implanted human nasopharyngeal carcinoma cell lines in nude mice. METHODS: Models of CNE1 and CNE2 xenograft in nude mice were established to investigate the anti-tumor effect of Sarcandra glabra. The apoptosis of CNE1 and CNE2 cells were observed with TUNEL and FACS with PI-staining. The ultra micro-structured changes of CNE1 and CNE2 cells were observed by transmission electron microscope. The expression of Bcl-2 and Bax of xenografts were investigated by immunohistochemistry. RESULTS: The Sarcandra glabra extracts significantly inhibited the growth of tumor when compared with normal control group. The expression of Bcl-2 was lower (P<0.01) and the expression of Bax of the Sarcandra glabra group was higher(P<0.01) than that of normal control group. The rate of cell apoptosis exhibiting was higher than that of normal control group(P<0.01). Electron microscopy indicated the apoptosis of tumor cells with marginal nuclei, chromatin condensation and nuclei fragmentation, and apoptotic bodies were observed. CONCLUSION: Sarcandra glabra suppresses the growth of tumor in vivo. The mechanism is associated with down-regulating the expression of Bcl-2 and up-regulating the expression of Bax to promote apoptosis.

Exosomes released by EBV-infected nasopharyngeal carcinoma cells convey the viral latent membrane protein 1 and the immunomodulatory protein galectin 9.

BACKGROUND: Nasopharyngeal carcinomas (NPC) are consistently associated with the Epstein-Barr virus (EBV). Their malignant epithelial cells contain the viral genome and express several antigenic viral proteins. However, the mechanisms of immune escape in NPCs are still poorly understood. EBV-transformed B-cells have been reported to release exosomes carrying the EBV-encoded latent membrane protein 1 (LMP1) which has T-cell inhibitory activity. Although this report suggested that NPC cells could also produce exosomes carrying immunosuppressive proteins, this hypothesis has remained so far untested. METHODS: Malignant epithelial cells derived from NPC xenografts--LMP1-positive (C15) or negative (C17)--were used to prepare conditioned culture medium. Various microparticles and vesicles released in the culture medium were collected and fractionated by differential centrifugation. Exosomes collected in the last centrifugation step were further purified by immunomagnetic capture on beads carrying antibody directed to HLA class II molecules. Purified exosomes were visualized by electron microscopy and analysed by western blotting. The T-cell inhibitory activities of recombinant LMP1 and galectin 9 were assessed on peripheral blood mononuclear cells activated by CD3/CD28 cross-linking. RESULTS: HLA-class II-positive exosomes purified from C15 and C17 cell supernatants were containing either LMP1 and galectin 9 (C15) or galectin 9 only (C17). Recombinant LMP1 induced a strong inhibition of T-cell proliferation (IC50 = 0.17 nM). In contrast recombinant galectin 9 had a weaker inhibitory effect (IC50 = 46 nM) with no synergy with LMP1. CONCLUSION: This study provides the proof of concept that NPC cells can release HLA class-II positive exosomes containing galectin 9 and/or LMP1. It confirms that the LMP1 molecule has intrinsic T-cell inhibitory activity. These findings will encourage investigations of tumor exosomes in the blood of NPC patients and assessment of their effects on various types of target cells.

Differential up-regulation of metallothionein isoforms in well-differentiated nasopharyngeal cancer cells in vitro by photoactivated hypericin.

Photoactivation of hypericin is known to generate reactive oxygen species and induce phototoxic effects. However, modulation of the cellular antioxidant defense would influence the extent and severity of the photodynamic effects. We have previously shown that hypericin-mediated photodynamic therapy (PDT) induced a significant reduction of Glutathione S-transferase activity. In this study, we investigated the phototoxic effects of hypericin-mediated PDT in nasopharyngeal cancer (NPC) in vitro and analyzed the expression of metallothionein (MT), a family of potential free radical scavengers. HK1 NPC cells were subjected to PDT treatment in vitro, and the effects on cell death were analyzed by flow cytometry (using propidium iodide and Annexin V staining) and transmission electron microscopy. The expression profile of MT-1E and MT-2A isoforms (the only functional MT isoforms expressed in HK1 NPC cells) were determined by quantitative real-time RT-PCR. The results showed that hypericin PDT induced necrotic cell death as evidenced by the absence of a subdiploid peak and decreased Annexin-V fluorescence. Ultrastructural examination verified the presence of cell necrosis. There was a significant up-regulation of MT-1E and MT-2A isoforms six hours following PDT, with an approximately 50-fold rise in the expression level of MT-1E and a 15-fold increase of MT-2A. Hence, despite the up-regulation of MT, cells still succumbed to PDT-induced necrosis. It appears that the oxidative stress induced by PDT overwhelmed the antioxidant defense mechanism such as the alteration of MT levels in tumor cells.

Intracellular co-localization of SPLUNC1 protein with nanobacteria in nasopharyngeal carcinoma epithelia HNE1 cells depended on the bactericidal permeability increasing protein domain.

Epithelial surfaces constitute natural immunobarriers against environmental threats. These barriers are brimming with fluids that bind, transport, cleave or degrade bacterial cells and their endotoxic by-products. Saliva and the airway surface-lining fluid (ASL) comprise the important fluid constituents. Short palate, lung and nasal epithelium clone 1 (SPLUNC1) is a potential host defensive protein that is secreted from the submucosal gland to the saliva and nasal lavage fluid. However, its antimicrobial spectrum and antimicrobial mechanism is not clear. Through green fluorescence protein (GFP) mediated subcellular localization experiments in nasopharyngeal carcinoma (NPC) HNE1 cell line, we determined that the intracellular GFP-tagged SPLUNC1 protein binds to a miniscule microorganisms, approximately 50-400nm in size, after the bactericidal permeability increasing protein (BPI) domain was deleted, GFP-tagged truncated SPLUNC1 protein lost its function of binding to the miniscule microorganisms. We verified that these microorganisms are nanobacteria (NB) with a negative staining using transmitted electronic microscope (TEM) and immunofluorescent analysis using an NB-specific antibody. We isolated and cultured the NB from the cultured nasopharyngeal carcinoma epithelia HNE1 cell supernatant. We found that the NB did not absorb the Hoechst stain, even when we extended the staining time to 35min. However, with the time extension the larger sized NB (larger than 300nm) did stain positively. From the biopsy specimen of NPC, we also detected the NB, which can lead to the swelling of mitochondria in the infected host cells. We hypothesize that SPLUNC1 and NB co-localization is due to the GFP-tagged SPLUNC1 protein binding to the lipopolysaccharide (LPS) of the Gram-negative NB, which can play an important role in the host defense of nasopharyngeal epithelium. This research sheds new light on the mechanism of SPLUNC1 involvement in the host upper respiratory tract defense system.

Morphometric analysis of AgNORs in nonkeratinizing carcinoma and adjacent normal epithelia in the nasopharynx.

OBJECTIVE: To evaluate the proliferative activity of different types of nonkeratinizing carcinoma and adjacent normal epithelia in the nasopharynx by the quantitative assessment of argyrophilic nucleolar organizer region (AgNOR) proteins. STUDY DESIGN: Silver staining of nucleolar organizer regions (NORs) was applied to 70 paraffin sections of nonkeratinizing carcinoma in nasopharyngeal biopsies. Fifty-four of the 70 cases had differentiated nonkeratinizing carcinoma (DNC), and the remaining 16 had undifferentiated carcinoma (UC). Nineteen of these 70 samples proved to contain, besides carcinoma, normal epithelia (NE), which was used as a control. The epithelial cells and cancer cells were analyzed for their AgNOR features by image cytometric analysis. RESULTS: As compared with normal epithelia, significant differences were found in mean nuclear area, AgNOR count, mean AgNOR area, AgNOR area ratio and AgNOR area/count ratio between NE and DNC (P < .05) and in mean nuclear area, mean AgNOR area and AgNOR area/count ratio between NE and UC (P < .001). Further, the differences in mean nuclear area, mean AgNOR area and AgNOR area/count ratio were statistically significant between DNC and UC. CONCLUSION: The evaluation of AgNORs is a useful histologic assessment of rapidity of cell proliferation in malignant and benign lesions and demonstrated that UC had more rapidly proliferative activity than DNC in this study.

Effect of heparin on apoptosis in human nasopharyngeal carcinoma CNE2 cells.

In order to study the mechanism of the effect of heparin on apoptosis in carcinoma cells, the nasopharyngeal carcinoma cell line CNE2 was used to identify the effect of heparin on apoptosis associated with the expression of c-myc, bax, bcl-2 proteins by use of Hoechst 33258 staining, terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL), agarose gel electrophoresis, and flow cytometry, as well as Western blot analysis. The results showed that heparin induced apoptosis of CNE2 cells including the morphologic changes such as reduction in the volume, and the nuclear chromatin condensation, as well as the "ladder pattern" revealed by agarose gel electrophoresis of DNA in a concentration-dependent manner. The number of TUNEL-positive cells was dramatically increased to 33.6+/-1.2% from 2.8+/-0.3% by treatment with heparin in different concentrations (10 to approximately 40 kU/L). The apoptotic index was increased to 32.5% from 3.5% by detecting SubG1 peaks on flow cytometry. Western blot analysis showed that levels of bcl-2, bax and c-myc were significantly overexpressed by treatment with the increase of heparin concentrations. These results suggest that heparin induces apoptosis of CNE2 cells, which may be regulated by differential expression of apoptosis-related genes.

Prognostic significance of argyrophilic nucleolar organizer regions in nasopharyngeal carcinoma.

Increased expression of argyrophilic nucleolar organizer regions (AgNORs) has been identified in certain malignant tumors including nasopharyngeal carcinoma (NPC). However, its prognostic significance in NPC is uncertain and remains to be evaluated. To address this we silver-stained 63 paraffin sections of NPC cases, and examined the correlation between AgNOR count and area, calculated by the CAS 200 image analysis system, and tumor behavior, locoregional control, and survival of patients. The mean AgNOR count and area were 1.62 +/- 0.31 and 3.98 +/- 11.4 microm2, respectively. The AgNOR area was positively associated with T stage (r = 0.26, P = 0.04). The Mann-Whitney test confirmed no significant difference in AgNOR area and count between patients with different outcomes. Multivariate analysis using the Cox proportional hazard model showed neither AgNOR count nor area to be significant predictors of actuarial survival or disease-free survival. It is concluded that AgNOR does not have an independent and significant prognostic value in NPC. AgNOR expression may be merely a reflection of malignant phenotype as well as cellular activity but not necessarily the ultimate behavior of the tumor.

Infiltrating lymphocytes in undifferentiated nasopharyngeal cancer lack metallothionein expression.

Metallothionein (MT) is a metal-binding protein with functional roles in cell growth, repair and differentiation. MT is reported to be differentially expressed in lymphocytes of malignant gastrointestinal lesions. The level of MT protein was examined by immunohistochemical analysis at light microscopic and ultrastructural level in infiltrating lymphocytes from 20 cases of undifferentiated nasopharyngeal carcinoma (NPC). MT expression was found to be absent in the infiltrating lymphocytes of NPC and in reactive lymphocytes of lymphoid hyperplasia in nasopharyngeal tissues. Ultrastructural examination confirmed the absence of MT immunoreactivity in the lymphoid infiltrate of NPC. On the other hand, malignant lymphoblasts of diffuse large cell lymphoma, showed MT-immunopositivity by immunoelectron microscopy. This study demonstrates a lack of MT expression in the lymphoid stroma of undifferentiated NPC, a further characteristic of its non-neoplastic nature.

Synthesis of biotinylated glyfoline for immunoelectron microscopic localization.

Antineoplastic glyfoline (1) has potent antitumor efficacy against various murine and human solid tumors. To elucidate the actual mechanism of action, we synthesized biotinylated glyfoline (B-Gly) and used it for the visualization of glyfoline-binding sites in nasopharyngeal carcinoma (NPC) cells. Under the electron microscope (EM), after cells were incubated for 6-36 h, the reaction products of anti-B-Gly were seen on some areas of the external cell surface and on the outer and inner membranes of the mitochondria. Pure EM morphology of NPC cells after glyfoline treatment revealed the similar morphological change of mitochondria. These findings indicate that the binding site of glyfoline in NPC is the inner membrane of the mitochondria, suggesting that B-Gly can be used as a marker for glyfoline localization.

Melanin pigmented oncocytic metaplasia of the nasopharynx.

A 64-year-old man presented with a history of discomfort of the throat of a few weeks' duration. Nasoscopic examination revealed multiple small, brown pigmentations at the left suprapharynx, the base of the left nasal cavity and the pharyngeal openings of the auditory tube on both sides. Microscopically, the lesion showed a glandular pattern of oncocytic epithelium with abundant pigmented granules and melanophages in the surrounding stroma. Immunohistochemically, the dendritic cells in the basal layer were positive for S-100 protein. Electron microscopic study revealed numerous fully melanized melanosomes and hypertrophied mitochondria in the oncocytic cells. Oncocytic cells do not produce melanin for themselves, melanin granules apparently being transferred from the adjacent dendritic cells to the oncocytic cells.

Plasmocitoma extramedular nasofaringeo. reporte de caso / Extramedulary plasmocytoma in the nasopharynx. case report

Los plasmocitomas extramedulares (PEM) son tumores solitarios de células plasmáticas localizada en lugares lejanos al hueso. Un porcentaje variable puede desarrollar con posterioridad un mieloma múltiple. Los PEM representan cerca de un 4 por ciento de los tumores no epiteliales del tracto respiratorio superior. Generalmente se desarrollan en el tejido submucoso de vías aéreas superiores con predilección por la nasofaringe, las fosas nasales, los senos paranasales y las amígdalas. Los tumores rinofaríngeos son raros; una revisión en Medline encontró 10 casos en la nasofaringe, uno de ellos en España. Presentamos el caso clínico de un paciente varón de 69 años, con patología tubárica crónica, cuyo examen clínico reveló la existencia de una lesión polipoide en nasofaringe, sin adenopatías cervicales. La resección endoscópica transnasal permitió el estudio histológico de la pieza, que mostró una proliferación de células plasmáticas. Los estudios séricos y de médula ósea permitieron concluir el diagnóstico de plasmocitoma extramedular. El tratamiento fue completado con radioterapia, no existiendo evidencia de recurrencia de la enfermedad después de 18 meses

Extranodal follicular dendritic cell tumour of the nasopharynx.

We report the first case of an extranodal follicular dendritic cell (FDC) tumour localized in the nasopharynx of a 44-year-old male patient. The tumour cells were characterized immunohistochemically by strong expression of CD21, HLA-DR and vimentin and focal expression of CD68 and cytokeratin. Electron microscopic examination revealed desmosomal cell junctions between adjacent cell processes. Molecular genetic analysis using polymerase chain reaction (PCR) showed germline configuration of immunoglobulin and T-cell receptor genes. Epstein-Barr virus (EBV) genomes were detectable by PCR. After complete surgical tumour removal and radiotherapy the patient is disease-free 20 months after the initial diagnosis.

Characterization of smoking-induced nasopharyngeal lymphoid hyperplasia.

The frequency of smoking-induced nasopharyngeal lymphoid hyperplasia in heavy smokers and its potential clinical implications are still unknown. Precise criteria to differentiate this entity from other types of nasopharyngeal lymphoid hyperplasia are needed. A prospective clinicopathological study of smoking-induced nasopharyngeal lymphoid hyperplasia was conducted in 17 heavy smokers. Ten nonsmoking patients, five of them with chronic sinusitis, three with adult-onset adenoid hypertrophy, and two children with adenoidal hypertrophy served as a control group. Both in smokers and in nonsmokers, lymphocytic infiltration of the mucosa was characterized immunohistochemically as T cells. In smokers, semithin (1 micron) sections revealed deformed and migrating cytotoxic lymphocytes in the nasopharyngeal mucosa. The lymphocytes were attached to epithelial, ciliated, and goblet cells, resulting in cell damage. Transmission electron microscopy of biopsies from smokers revealed emperipolesis, characterized by mucosal invasion and epithelial cell damage by an unusual population of migrating T lymphocytes that penetrate them. These findings confirm a direct effect of smoking on the nasopharyngeal lymphoid tissue, which forms part of the immune system. It is concluded that the diagnostic evaluation and therapeutic approach of heavy smokers with otological and airway symptoms should be based on thorough endoscopic examination of the nasopharynx. When the diagnosis is not clear-cut, selective tele-endoscopic biopsy and electron microscopic examination are recommended. This entity should be added to the list of known clinical manifestations of the smoking habit.