Normal Nasopharynx Research Articles

Identification of Genes Related to Nasopharyngeal Carcinoma with the Help of Pathway-based Networks

cDNA microarray is a powerful tool to analyze simultaneously the expression levels of tens of thousands of genes. Compared with normal nasopharynx (NP) tissues, 2210 genes were highly differentially expressed in nasopharyngeal carcinoma (NPC) tissues detected by cDNA microarray. Since signal pathway is widely used to describe the complex relationship between genes, a pathway-based network was constructed to visualize the connection between the genes obtained from microarray data in this report. We analyzed the targeted genes that may have more important influence on this gene network with statistical methods and found that some genes might have significant influence on this network, especially Ras-related nuclear protein (RAN), carboxyl ester lipase (CEL), v-rel reticuloendotheliosis viral oncogene homolog A (RELA) genes. To verify the results from pathway-based selection, reverse transcription-polymerase chain reaction (RT-PCR) and real-time RT-PCR were performed to detect the expression levels of RAN, CEL and RELA genes and it was found that the RAN and CEL genes were significantly up-regulated in more than 80% of NPC tissues. To further elucidate the function of the RAN gene, RAN expression was specifically suppressed in a 5-8F NPC cell line by RNA interference (RNAi). As expected, the depletion of RAN could effectively block the proliferation of tumor cells. Therefore, our study may open up a new way to analyze the vast microarray data.

Transcriptional gene expression profile of human nasopharynx

Inflammation in the nasopharynx is very common worldwide and nasopharyngeal carcinoma (NPC) results in significant morbidity and mortality in southeast Asia and north Africa. To facilitate the understanding of pathogenesis of these diseases as well as normal nasopharynx biology, transcriptional gene expression profile of normal human nasopharynx, from undissected biopsies, was established in this study by generating a large amount of ESTs, followed by bioinformatics analysis. A total of 27,209 ESTs generated from human nasopharynx cDNA library were integrated into 8,420 non-redundant clusters, of which, 6,070 (72.09%) corresponded to known genes, 156 (1.85%) to known ESTs, and 2,194 (26.06%) to novel sequences, respectively. Functional classification revealed that transcripts constituting enzymes (2,284, 28.30%) and those participating in cell growth/maintenance (3,306, 46.33%) were the largest population expressed in the nasopharynx, followed by genes coding for binding proteins (2,135, 26.45%) and involved in cell communication process (1,832, 25.68%). In addition, through comparison of the nasopharynx gene expression profile with those of 7 other human tissues, 59 transcripts preferentially expressed and 22 transcripts unique in the nasopharynx were identified. Our study acquired an initial assessment of qualitative diversity of gene expression in the nasopharynx, providing the first step toward comprehensive characterization of the molecular features of the nasopharyngeal disorders.

Observer variation in delineation of nasopharyngeal carcinoma for radiotherapy, a 3-D analysis

Observer variation in delineation of nasopharyngeal carcinoma for radiotherapy, a 3-D analysis

Virtual endoscopy of the nasopharynx in the evaluation of its normal anatomy and alterations due to lymphoid hyperplasia: preliminary report.

The purpose of this study was to evaluate the diagnostic usefulness of virtual endoscopy in establishing the anatomic appearance of nasopharynx, both normal and affected by lymphoid hyperplasia. Thirty-seven patients affected by chronic rhinosinusal and otomastoid pathology, all studied by rhinoscopy, were examined with multislice computed tomography (CT) and virtual endoscopy of the nasopharynx. Rhinoscopy showed a completely normal nasopharynx in 15 cases and a variable grade of lymphoid hypertrophy in 22 patients. A general agreement was observed between traditional and virtual endoscopy findings in both subgroups. The tasca of Luschka was detected in 13/15 of normal subjects and only in 3/22 patients. The Rosenmuller fossae appeared deeper in normal subjects and their symmetry could be considered an important criterion of normality. In all cases, a good evaluation of the tubaric ostium was obtained. Differentiation between hyperplasic lymphoid tissue and neoplasms is possible only in lymphoid hyperplasia characterized by median crest-like swelling with a narrow base. In most cases, differential diagnosis cannot be based only on morphological criteria of virtual endoscopy, but it should be evaluated considering the overall CT findings and clinical presentation.

Identification and characterization of a novel nasopharyngeal carcinoma-associated peptide: NAP-1

Nasopharyngeal carcinoma (NPC) is one of the most commons cancers in Southeast Asia and Southern China. Several NPC-associated genes have been so far described and here we describe the identification and the characterization of a novel nasopharyngeal carcinoma-associated peptide: NAP-1. NAP-1 was identified with the human genome draft searching method combined with nested PCR mapping of the chromosome 4q13 region. NAP-1 encodes an 85 amino acid alkaline peptide with a calculated isoelectric point of 9.3, three phosphorilation sites and a proline-rich region. Northern blot analysis revealed that NAP-1 is expressed as a 0.6 kb transcript in normal lymph nodes and trachea. In addition, reverse transcription (RT)-PCR showed that NAP-1 is expressed not only in NPC but in normal nasopharynx (NP) and various other tumors and tissues of the head and neck including: tonsils, lymph nodes, carcinoma of the tonsil, T cell lymphomas, squamous cell carcinoma of the hard palate, papilloma of the nasopharynx, nasopharyngitis, lymphoma of the tongue root and follicular dendritic cells (FDC). In addition, NAP-1 is not expressed in normal tissues or tumors from other anatomical regions and was not expressed by NPC cell lines. Surprisingly, differential RT-PCR demonstrated decreased expression of NAP-1 in NPC compared with paired NP biopsies in 42.5 % of cases (17 out of 40). In addition, in situ hybridization and immunohistochemistry demonstrated that NAP-1 is expressed by S100+ CD35+ FDCs of the germinal center and not in other normal immune cells infiltrating NP or NPC. Therefore, it is likely that NAP-1 is secreted by FDC in the NP and may play an immune modulatory role in NPC.

In vivo diagnosis of nasopharyngeal carcinoma using contact rhinoscopy.

To evaluate the potential use of contact endoscopy for the diagnosis of nasopharyngeal carcinoma (NPC). Prospective study to examine the nasopharynx of 30 patients with nasopharyngeal carcinoma and 18 subjects with normal nasopharynx in a clinic setting using contact rhinoscopes (Karl Storz, Tuttlingen, Germany, 7215 AA, 00 and 7215 BA, 300; 23 cm long; 4 mm in diameter). The superficial cells of the normal nasopharynx and the nasopharyngeal tumors were stained with 1% methylene blue and examined with contact rhinoscopes at high magnifications (x 60 and x 150). The areas under examination were then biopsied. The contact endoscopic images were compared with the corresponding hematoxylin and eosin-stained histologic sections of the biopsied tissues. Sixty-six procedures were performed in 48 patients. The images of normal pseudostratified ciliated epithelium and squamous epithelium were readily recognized by contact endoscopy in all subjects with normal nasopharynx (10 men and 8 women; mean age, 51.9 y). Twenty-six of 30 patients with NPC (86.6%; 18 men and 8 women; mean age, 50.6 y) were successfully examined by contact endoscopy under local anesthesia. In these 26 patients, two patterns of malignant cells were identified with contact endoscopy. The patterns of contact endoscopic images corresponded well with the histologic findings. Contact endoscopy is an accurate and reliable office-based procedure, which allows for in-vivo diagnosis of nasopharyngeal carcinoma.

Cloning of a novel gene associated with human nasopharyngeal carcinoma

One EST N27741 with high expression in normal adult nasopharynx tissues but low expression in adult poorly differentiated squamous nasopharyngeal carcinoma has been selected out by the high-density cDNA array expression profiling technique. The differential expression has been confirmed by RT-PCR. One novel gene of 1096 bp has been cloned based on this EST. Bioinformatics analysis found that the new gene sequence contains a whole reading frame encoding 256 amino acids. There is a stop codon TAA in front of the 5′ end start codon, and a tailing signal AATAAA and poly A tail at the 3′ end. There is no homologous known gene found after searching by blasting this sequence to non-redundancy nucleotide database. Therefore it is considered a novel gene related to nasopharyngeal carcinoma.

Elevated expression of thyroid hormone receptor alpha 2 (c-erb A- alpha 2) in nasopharyngeal carcinoma.

Differential display was used to identify genes differentially expressed between cultured normal nasal epithelial cells and nasopharyngeal carcinoma (NPC) cell lines. A 130 bp cDNA fragment showing homology with thyroid hormone receptor α2 (TR-α2 or c-erb A-α2) was identified in NPC cell lines. Northern blot analysis using the 130 bp cDNA fragment and a TR-α2 specific cDNA containing part of the coding region as probes, we were able to detect a 2.7 kb transcript corresponding to that of TR-α2 in NPC cell lines but not in normal nasal epithelial cells. RNA in situ hybridization was used to detect TR-α2 expression in clinical biopsies obtained from NPC patients and non-tumour controls. TR-α2 mRNA was detected in 1 out of 24 (4.2%) normal nasopharynx epithelium biopsies, in 5 out of 27 (18.5%) primary and 15 out of 24 (62.5%) recurrent tumours. The positive rate of TR-α2 expression in recurrent NPC biopsies was significantly higher than that in normal nasopharynx epithelium (P < 0.00001). The relevance of the elevated expression of TR-α2 in the pathogenesis process of NPC was discussed. © 2000 Cancer Research Campaign http://www.bjcancer.com

Profiling gene expression patterns of nasopharyngeal carcinoma and normal nasopharynx tissues with cDNA microarray

5 μg of total RNAs from normal nasopharynx and nasopharyngeal carcinoma tissue have been labeled with α-32P-dCTP during reverse transcription. The synthesized cDNA probes have been hybridized to high-density cDNA microarray containing 5184 genes or expression sequence tags (ESTs). Then image analysis software has been applied to comparing their expression profiles. Results show that 187 ESTs were of density value above 200 in nasopharyngeal carcinoma tissue while there were 307 such ESTs in normal nasopharynx tissue; 38 ESTs were strongly expressed in nasopharynx, but weakly expressed in nasopharyngeal carcinoma; 48 ESTs were strongly expressed in nasopharyngeal carcinoma, but weakly expressed in normal nasopharynx. These results suggest that there may exist some new differentially expressed genes involved in nasopharyngeal carcinoma development. Furthermore, the results strongly indicate that high-density cDNA microarray is a powerful and efficient tool for large-scale screening differentially expressed genes.

11C-acetate clearance in nasopharyngeal carcinoma.

This study assessed 11C-acetate turnover (clearance) in nasopharyngeal carcinoma (NPC). Data were acquired by dynamic PET after the intravenous injection of 4.625 MBq.kg-1 body weight of 11C-acetate for 30 min. Tomograms were reconstructed and evaluated visually. A time-activity curve of the nasopharynx and neck was generated and the clearance rate of 11C-acetate from the nasopharynx in the slow phase and from NPC was calculated using 0.693/T1/2. Ten patients with nasopharyngeal carcinoma and nine normal subjects were studied. The clearance of 11C-acetate from the normal nasopharynx was rapid and biexponential, in contrast to the rapid uptake followed by extremely slow clearance in patients with NPC. The clearance rate (mean +/- S.D.) was 0.0074 +/- 0.0042 in NPC and 0.0263 +/- 0.0152 in controls in the slow phase, being significantly different between the two groups with no overlap. All nasopharyngeal carcinomas were clearly visualized, in contrast to no obvious retention in the normal nasopharynx. Our initial results indicate that 11C-acetate clearance can be used to differentiate nasopharyngeal carcinoma from a normal nasopharynx. This finding may lead to new applications of 11C-acetate in oncology.

Fluorine-18 fluoromisonidazole tumour to muscle retention ratio for the detection of hypoxia in nasopharyngeal carcinoma

In vivo demonstration of hypoxia is of significance for tumour patient management. Fluorine-18 fluoromisonidazole ([18F]FMISO) is a proven hypoxic imaging agent. We developed an [18F]FMISO tumour to muscle retention ratio (TMRR) for the detection of tumour hypoxia in nasopharyngeal carcinoma (NPC). Data were acquired by positron emission tomography (PET) of the nasopharynx and neck after intravenous injection of 370 MBq of [18F]FMISO. Two imaging protocols were adopted: a long protocol for comprehensive dynamic information and a short protocol for a simple, clinically convenient imaging procedure. Tomograms were reconstructed and evaluated visually. ROI analysis on the basis of time-activity curve evaluation was performed to calculate the TMRR of NPC or cervical nodal metastases (CNMs) in relation to the suboccipital muscles at 2 h. The calculation of the TMRR was exactly the same for both the long and the short protocol as two 30-min composite frames had been created immediately after intravenous injection and 2 h after injection of [18F]FMISO in the long protocol. The normal tissue to muscle retention ratio (NTMRR) was derived similarly from the normal nasopharynx. The data of 12 controls and 24 patients with NPC were analysed. The long protocol was used in 15 patients, and the short protocol in nine. In controls, the mean NTMRR+/-1 SD was 0.96+/-0.14. The mean TMRRs for NPC and CNMs were 2.56+/-1.50 and 1.35+/-0.51, respectively; these values were significantly higher than the mean NTMRR for normal controls (P<0.005 in each case). At the retention threshold value of 1.24, tumour hypoxia occurred in 100% of the primary lesions of NPC and 58% of CNMs. The TMRR for undifferentiated carcinoma was significantly lower than that for non-keratinized carcinoma (P<0.05). The [18F]FMISO TMRR is a simple and clinically useful index for detecting tumour hypoxia in NPC.

Detection of an epstein‐barr‐virus variant in T‐cell‐lymphoma tissues identical to the distinct strain observed in nasopharyngeal carcinoma in the taiwanese population

An EBV variant has been identified in NPC tissues in Taiwan. This EBV variant contains a point mutation in exon I of the LMP I gene. This mutation results in the loss of an XhoI site at nt 169,426, which is present in strain B95-8. In addition, this variant contains a 30-bp deletion in exon 3 of the gene. The recent demonstration of the prevalence of EBV-containing nasal and peripheral T-cell lymphoma in this region drove us to evaluate the presence of this NPC-EBV strain in 7 cases of T-cell lymphoma, as well as in 48 NPC tissues, 2 cases of Hodgkin's disease and I B-cell lymphoma. Four samples of normal lymph node tissue, 40 of normal nasopharynx tissue and 78 throat washings of healthy individuals were included for comparison. We used sequence-specific primers and the polymerase chain reaction (PCR) method to amplify LMP I gene fragments containing these variations. Mutations were then confirmed by restriction-enzyme digestion and the DNA sequencing analysis. Our results showed that 57 of 58 tumor-tissues samples were EBV-positive. Among them, 56, including 6 T-cell-lymphoma samples, belonged to the NPC strain. This strain of EBV was also present in 92% of EBV-positive normal nasopharynx tissues and in 84% of EBV-positive throat washings of the healthy individuals tested. These results suggest that the NPC-EBV strain is prominently present in Taiwan.

Analysis of epstein‐barr virus infection in nasopharyngeal biopsies from a group at high risk of nasopharyngeal carcinoma

Although Epstein-Barr virus (EBV) is consistently associated with the epithelial malignancy nasopharyngeal carcinoma (NPC), it is not clear to what extent the normal virus carrier state involves infection of nasopharyngeal epithelium. We attempted to examine this question by screening 26 nasopharyngeal punch biopsies from EBV-carrying Chinese Malaysians who had presented with clinical symptoms possibly indicative of NPC, but in whom histological analysis of an adjacent biopsy had revealed no evidence of tumour. Assays included (i) in situ hybridization with 35S-labelled riboprobes specific for EBERs (rather than with BamHI W DNA probes which can give false-positive results); (ii) cDNA amplification across defined splice junctions of the EBNA1 and BamHI A transcripts expressed in latently-infected NPC cells and of the BHRF1 lytic-cycle transcript; and (iii) immunostaining for the immediate early lytic-cycle protein BZLF1. Of the 26 biopsies examined, all 23 showing normal nasopharyngeal histology were consistently negative for both latent and lytic-cycle markers. The other 3 cases were all positive for EBNA1 and BamHI A transcripts; these RNAs were almost certainly of tumour rather than normal-cell origin since these particular biopsies were the only ones to reveal localized foci of EBER-positive NPC cells; such biopsies were again negative for lytic-cycle markers. We provisionally conclude that EBV infection of the normal nasopharynx is not a regular feature of the virus carrier state and that screening nasopharyngeal biopsies for viral RNA markers of the latent cycle could be useful in NPC diagnosis.

Expression of HLA-DR antigens in nasopharyngeal carcinoma: an immunohistological analysis of the tumour cells and infiltrating lymphocytes.

A panel of conventional and monoclonal antibodies was used to examine the immunohistological characteristics of malignant epithelial cells and infiltrating lymphocytes in frozen sections of nasopharyngeal carcinoma (NPC) biopsies from 10 Tunisian patients. Three main categories of cells were identified. (1) Tumour cells which were positive for Epstein-Barr nuclear antigen, HLA-ABC and keratin determinants. In most samples, the tumour cells also expressed variable amounts of HLA-DR antigens. The presence of HLA-DR antigens has not been previously reported in NPC and may be a contributory factor in effecting the transfer of Epstein-Barr virus to the epithelial cells. (2) Infiltrating lymphocytes which were mainly composed of T inducer (T4+) and T suppressor/cytotoxic (T8+) cells although one sample contained predominantly immature T cells expressing the HTA-I+ cortical thymocyte phenotype. Few B cells or natural killer cells were demonstrated. (3) Large HTA-I+ dendritic cells which were invariably present within the tumour masses. These were morphologically and phenotypically similar to antigen presenting Langerhans cells which are usually located in the skin but also found in other epithelial sites. These cells may be a residual population from the normal nasopharynx or represent part of a specific immunological response to the presence of Epstein-Barr virus in the epithelial cells.

Infection of human epithelial cell lines by Epstein-Barr virus. Interaction between epithelial cell and B lymphocyte.

The pathogenesis of nasopharyngeal carcinoma caused by the Epstein-Barr virus (EBV) has been studied experimentally by infecting monolayer cells derived from human normal nasopharynx with the B-lymphotropic EBV. Direct EBV infection of the cell sheets derived from the human nasopharynx resulted in the appearance of EBV-associated nuclear antigen-positive floating cells, suggesting that the monolayer cells have been transformed. Since these cells seemed to be of the B-type lymphocyte, it may be assumed that there must have been B lymphocytes among the cells of the monolayer which have undergone transformation by the virus. EBV infection of fused human epithelial cells (Ad-AH and D98-AH cells) and B-lymphoblastoid cells (BJAB cells) showed that the EBV receptors had been maintained for no longer than 24 h even when heterokaryons and hybrid cells were formed.

IgA protease production as a characteristic distinguishing pathogenic from harmless neisseriaceae.

IgA proteases are extracellular enzymes of bacteria that have human immunoglobulin A of the IgA1 subclass as their only known substrate. The identification of this enzyme in neisseria prompted us to determine whether IgA protease production correlates with pathogenicity within this genus. Multiple clinical isolates of Neisseria gonorrhoeae, N. meningitidis and eight species of non-pathogenic neisseria that commonly colonize the normal human nasopharynx were examined for IgA protease activity. All N. gonorrhoeae and N. meningitidis strains were enzyme positive; all non-pathogenic strains were negative. Among meningococci, the enzyme occurred in strains carried harmlessly in the nasopharynx as well as those isolated from systemic infections. Because mucosal immune defense is largely mediated by antibodies of the IgA isotype, the finding that IgA protease activity is linked specifically to the pathogenic neisseria suggests that the enzyme may be involved in the pathogenesis of neisserial infection.

Contrast nasopharyngography of angiofibromata.

PHYSICAL examination of the nasopharynx is often inadequate, even in the most cooperative patient. This is especially true in the youthful patient in whom a nasopharyngeal angiofibroma is suspected. Contrast nasopharyngography is a safe, simple, and painless procedure that yields useful information especially where arteriography is unavailable or unfeasible. Contrast nasopharyngography was first described in 1934 by Ruedi and Zuppinger.1The only recent reports of this method in the English literature are those of Jing and McGraw2who describe the normal and abnormal nasopharynx and Morgan and Evison3who report their experience in the follow-up of two nasopharyngeal carcinomas. Contrast nasopharyngography of nasopharyngeal angiofibromata has not been previously described in the literature. That is the purpose of this report. Materials and Method No special equipment or preparation is necessary. It is advisable to obtain a sinus series before this study to avoid bothersome residual contrast material. The

Alterations in the bacterial flora of the throat during oral therapy with aureomycin.

THE BACTERIAL flora of the normal nasopharynx may be altered significantly during the therapeutic administration of sulfadiazine, 1 penicillin 2 or streptomycin. 3 Usually these changes are specific and selective, so that species of organisms which are highly susceptible to the drug are eliminated rapidly. More resistant groups of bacteria, which may be present in small numbers before therapy or may enter after therapy is begun, then multiply and become the predominant organisms during the first week of treatment. If these relatively drug-fast organisms are pathogenic, they may initiate a new bacterial infection in the patient during the course of treatment for the primary disease. 4 Furthermore, these strains may be transmitted to others, causing infections that require different antibacterial drugs for treatment. 5 Studies of the effect of aureomycin on the normal flora of the body have been limited to the micro-organisms in the gastrointestinal 6 and genital tracts. 7 Collins, Gocke and Finland, 8

Variations in the Fermentative Capacity of Neisseriae

Apart from the meningococcus and gonococcus, adequate characterization of the aerobic gram-negative diplococci is lacking. The American scheme as described in Bergey's Manual of Determinative Bacteriology (Breed et al?) presents six distinct species, while the British school (Wilson and Miles) favors the establishment of one species, Neisseria pharyngis, which would include all of the saprophytic neisseriae with the possible exception of N. catarrhalis. These divergent interpretations have their origin in numerous publications with conflicting data relative to pigmentation, colonial structure and biochemical activity of gram-negative cocci of the normal nasopharynx. The subject is reviewed by Wilson and Miles. A possible explanation of discrepancies in the biochemical determinations (carbohydrate fermentations) may be found in the manner of performance of such tests and, more specifically, in the nature of the media employed, since individual preference has been exercised in the selection of the basal medium to which carbohydrates were added. It has been found that the nitrogen component of a medium may influence carbohydrate utilization (Orla-Jensen, Sadler, Eagles and Pendray, Katznelson, Burrows and Salmoiraghi). This investigation was undertaken to determine the effect of a variety of basal media on the fermentative ability of 10 cultures of nonpathogenic aerobic neisseriae.