Nasopharyngeal carcinoma: genetic changes, Epstein-Barr virus infection, or both. A clinical and molecular study of 36 patients

Correlation of microvascular density and proliferation index in undifferentiated nasopharyngeal carcinoma

Background: Undifferentiated nasopharyngeal carcinoma is a highly malignant tumor with an endemic distribution. Several histologic parameters have been studied to provide prognostic information for patient management. Both proliferation index and microvascular density are commonly determined on such tumors, but the relationship between these two parameters has not been studied fully. Objectives: Determine the association between microvascular density and cellular proliferation in undifferentiated nasopharyngeal carcinoma. Methods: A series of 60 cases were studied in patients of Southeast Asian origin. Cellular proliferation was determined using Ki67 immunostaining, and vessel proliferation using CD31 immunostaining in terms of areas of increased staining (‘hot spots’). Ki67 results were scored on a scale of 0-4+ and CD31 results as a microvascular density/mm2. Results: The mean of the microvascular density was 22/mm2 in the Ki67-negative group (25 cases). In the Ki67- positive group (35 cases), the mean was 35/mm2. The difference between the positive and negative group was statistically significant (p <0.001). Microvascular density significantly increased as the Ki67 score increased (p<0.001). However, the ‘hot spots’ for microvascular density in tissue sections did not correspond to areas of increased cellular proliferation. Conclusion: Pathologists usually determine only one of these two prognostic factors when dealing with undifferentiated nasopharyngeal carcinoma. The proliferation index is suggested because it is easier to perform and can be done on small biopsies not to contain enough surface area for microvascular density determination.

Modes of infection and oncogenesis by the Epstein-Barr virus

The EBV is a human γ-herpesvirus associated with various neoplasms. It is responsible for causing cancers of B, T, and NK cells as well as cells of epithelial origin. Such diversity in target cells and the complicated steps of oncogenesis are perplexing when we speculate about the mechanisms of action of EBV-positive cancers. Here, we first note three common features that contribute to the development and maintenance of EBV-positive cancers: effects of EBV oncogenes, immunosuppression and evasion/exploitation of the immune system, and genetic and epigenetic predisposition/alteration of the host genome. Then, we demonstrate the mechanisms of oncogenesis and the means by which each EBV-positive cancer develops, with particular focus on the mode of EBV infection. The EBV has two alternative life cycles: lytic and latent. The latter is categorized into four programs (latency types 0-III) in which latent viral genes are expressed differentially depending on the tissue of origin and state of cells. The production of viral latent genes tends to decrease with an increase in time, and, in an approximate manner, the expression levels of viral genes are inversely correlated with the degree of abnormalities in the host genome. Occasional execution of the viral lytic cycle also contributes to oncogenesis. Understanding this life cycle of the EBV and its relevance in oncogenesis may provide valuable clues to the development of effective therapies for the associated cancers.

[Lifecycles of EBV and cancer]

Epstein-Barr virus (EBV) is a member of gamma-herpesvirus, which can cause various types of tumor. Coexisting with the host for a long period of time, it has evolved unique and sophisticated strategy for survival by taking complicated, tactical modes of infection. Such modes include latent and lytic infections, and latent state is further categorized into four types. Differences and transitions in such lifestyles are significantly associated not only with virus amplification, but also with pathology and advancement of the disorders. I here review oncogenesis and pathogenesis of EBV-related disorders, especially focusing on our recent results on the modes of EBV infection.

Periostin, a stroma-associated protein, correlates with tumor invasiveness and progression in nasopharyngeal carcinoma

Recently, the tumor microenvironment is increasingly recognized as playing an important role in cancer proliferation, invasion, and metastasis. To screen stroma-associated proteins involved in nasopharyngeal carcinoma (NPC) carcinogenesis, laser capture microdissection (LCM) and quantitative proteomic analysis were employed to assess different protein expression of the stroma between NPC and normal nasopharyngeal mucosa (NNM). In this study, periostin was identified to be significantly up-regulated in NPC stroma compared with NNM stroma and the result was further confirmed by Western blotting. Immunohistochemistry showed that over-expression of periostin was frequently observed in the stroma of NPC and matched lymph node metastases (LNM) compared with the stroma of NNM. Statistical analysis showed over-expression of periostin was significantly associated with advanced clinical stage (P < 0.001) and lymph node metastasis (P < 0.001) and decreased overall survival (P < 0.001) in NPC. Cox regression analysis indicated over-expression of periostin was an independent prognostic factor. Furthermore, ectopic expression of periostin was used to examine its effect on invasiveness of NPC cell in vitro and the result showed that periostin was able to promote invasiveness of NPC cell. In conclusion, periostin expression is correlated with tumor stage, lymph node metastasis, and patient survival. Periostin is a potential biomarker for the differentiation and prognosis of NPC, and it might play an important role in the progression of NPC.

The dominance of China 1 in the spectrum of Epstein-Barr virus strains from Cantonese patients with nasopharyngeal carcinoma

Nasopharyngeal carcinoma is a disease with a remarkable geographic and ethnic distribution, and has a high incidence in southern China. Infection with Epstein-Barr virus (EBV) is an important contributing factor. The profile of EBV strains in Cantonese patients from Guangdong, the nasopharyngeal carcinoma endemic region in southern China, is described on the sequence variations in latent membrane protein 1 carboxyl-terminus. The results show that China 1 was the dominant EBV strain detected in both the tumor biopsies and samples of throat washings, whereas multiple strains, including China 1, China 2, B95-8, and Med, were detected in blood samples. In addition, a new strain named China 4 was found in blood samples. These findings suggest that the host population is susceptible to the predominant China 1 strain in the nasopharyngeal carcinoma endemic region of China, but its relationship with the host remains to be characterized further.

Nasopharyngeal carcinoma

Imaging plays an important role in the staging of nasopharyngeal carcinoma. Accurate staging is necessary, as the treatment is directly dependent on stage. Clinical examination provides information on mucosal involvement but is unable to determine the deep extension or the presence of skull base invasion or intracranial spread. The intent of this manuscript is to provide information of the specific imaging findings that will directly affect the stage and treatment of nasopharyngeal carcinoma as well as post-treatment complications.

Distribution of Epstein-Barr virus genotypes in throat washings, sera, peripheral blood lymphocytes and in EBV positive tumor biopsies from Slovenian patients with nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is a malignancy closely associated with Epstein-Barr virus (EBV). It is prevalent among the Chinese of Southern China, whereas outside China, the position seems to be different. The aim of this study was to determine the distribution of EBV genotypes in the patients with NPC in Slovenia, which is a nonendemic area. Detection of EBV was undertaken by testing the throat washes, sera, peripheral blood lymphocytes (PBLs), and biopsies of primary tumors of 48 patients with NPC in Slovenia. The sera of 20 patients with serologically confirmed primary EBV infection served as a control clinical material. The analysis of genotypes was carried out on three regions of EBV genome; BamHI WYH, BamHI I, and BamHI F, using the polymerase chain reaction (PCR) and restriction fragment length polymorphism (RFLP). The results show that, in Slovenia, the predominant combination of EBV genotypes based on the differences in the three genomic regions is ADF. This combination was found in 56 out of 103 different EBV positive clinical samples (throat washes, sera, PBLs, and tumor biopsies) of patients with NPC and in 15 out of 17 sera of patients with primary EBV infection. Very low number of genotypes C and f were detected, in spite of the fact that these two genotypes were considered to be associated with the development and/or maintenance of NPC in Southern China. Genotype f was found in only two tumor biopsies; in all other clinical samples (throat washes, sera and PBLs), genotype F was detected. Genotype C was proven in 31/103 clinical samples, with the highest percentage in tumor biopsies (37.5%). As in the NPC patients from other countries (Alaska is an exception), genotype A was predominant and was detected in 86/103 clinical samples. Genotype B was found in 15 clinical samples of patients with NPC and in 3 the two genotypes A and B were found. In comparison to China, these results show different EBV genotypes distribution. It seems that the genetic disposition of human population is an important factor that may contribute to different susceptibility for specific EBV genotypes.

The expression of p63 is associated with the differential stage in nasopharyngeal carcinoma and EBV infection

Background

Nasopharyngeal carcinoma (NPC) is common among Southern Chinese and the main histology is the undifferentiated carcinoma associated with Epstein-Barr virus (EBV) infection. p63 is a recently proved member of the p53 family based on the structural similarity to p53, but its function in NPC is still unknown. This study was aimed to investigate the association between p63 and NPC.

Results

p63 was expressed in 100%(202/202) of nasopharyngeal carcinoma (NPC) tissues but not in 29 nasopharynx inflammation and 17 non-cancerous nasopharyngeal epidermises on a tissue microarray by immunohistostaining. Further investigation suggested that the p63 expression was associated with the differential stage of NPC: p63 strong staining in Keratinizing squamous cell carcinoma, differentiated non-keratinizing NPC and undifferentiated non-keratinizing NPC presented the percentage of 5/8 (62.5%), 43/48 (92.5%) and 50/50 (100%), respectively. A significant difference (p = 0.001) existed between the keratinizing and non-keratinizing groups. No pathogenic mutations were detected in p63 gene in 12 primary NPC tissues and matched peripheral blood lymphocytes (PBL). Half-life measurement study revealed distinct stability of p63 protein in the different cell lines, especially between the carcinoma cell lines with EBV infection and the non-cancerous cell lines. The results of immunoprecipitation suggested a direct interaction between Epstein-Barr virus nuclear antigen 5 (EBNA-5) and p63 protein in NPC, and this binding would increase the stability of p63.

Conclusion

Our data suggested p63 might be used as an adjunct diagnostic marker of NPC and contributed a new way to understand the contribution of the EBV in the pathogenesis of NPC.

Frequent hypermethylation of RASSF1A and TSLC1, and high viral load of Epstein-Barr Virus DNA in nasopharyngeal carcinoma and matched tumor-adjacent tissues

We examined the promoter hypermethylation of tumor-suppressor genes RASSF1A and TSLC1, quantitated EBV DNA load in nasopharyngeal carcinoma (NPC) tissues (T tissues), and matched tumor-adjacent tissues outside 0.5 cm (P tissues) and outside 1.0 cm (Z tissues) to evaluate the role of promoter hypermethylation of RASSF1A and TSLC1 as well as viral load in the pathogenesis of NPC. Methylation-specific polymerase chain reaction (PCR) for RASSF1A and TSLC1 and quantitative real-time PCR analysis of EBV DNA were performed on matched T, P, and Z tissues (n = 28) as well as chronic nasopharyngitis tissues (n = 8). Hypermethylated RASSF1A was frequently detected in the T (82%) and P tissues (75%), but less frequently in Z tissues (46%). he average quantities of EBV DNA (copies/microg DNA) in matched T, P, and Z tissues were 673,000, 90,000, and 7000. The differences of promoter hypermethylation of RASSF1A and EBV viral load among T, P, and Z tissues were statistically significant, with more frequent methylation and higher viral load detected when tissues examined were nearer to the NPC tissues. Our results suggest that aberrant hypermethylation of RASSF1A and high EBV load might be important events in NPC pathogenesis, and they may be useful molecular diagnostic markers for this cancer.

Epstein-Barr virus and cancer

EBV was the first human virus to be directly implicated in carcinogenesis. It infects >90% of the world's population. Although most humans coexist with the virus without serious sequelae, a small proportion will develop tumors. Normal host populations can have vastly different susceptibility to EBV-related tumors as demonstrated by geographical and immunological variations in the prevalence of these cancers. EBV has been implicated in the pathogenesis of Burkitt's lymphoma, Hodgkin's disease, non-Hodgkin's lymphoma, nasopharyngeal carcinoma, and lymphomas, as well as leiomyosarcomas arising in immunocompromised individuals. The presence of this virus has also been associated with epithelial malignancies arising in the gastric region and the breast, although some of this work remains in dispute. EBV uses its viral proteins, the actions of which mimic several growth factors, transcription factors, and antiapoptotic factors, to usurp control of the cellular pathways that regulate diverse homeostatic cellular functions. Recent advances in antiviral therapeutics, application of monoclonal antibodies, and generation of EBV-specific CTLs are beginning to show promise in the treatment of EBV-related disorders.

Gamma herpesviruses: pathogenesis of infection and cell signaling

Altered cell signaling is the molecular basis for cell proliferation occurring in association with several gamma herpesvirus infections. Three gamma herpesviruses, namely EBV/HHV-4, KSHV/HHV-8 and the MHV-68 (and/or MHV-72) and their unusual cell-pirated gene products are discussed in this respect. The EBV, KSHV as well as the MHV DNA may persist lifelong in an episomal form in the host carrier cells (mainly in lymphocytes but also in macrophages, in non-hornifying squamous epithelium and/or in blood vessel endothelial cells). Under conditions of extremely limited transcription, the EBV-infected cells express EBNA1 (EB nuclear antigen 1), the KSHV infected cells express LANA1 (latent nuclear antigen 1), while the MHV DNA carrier cells express the latency-associated protein M2. With the full set of latency-associated proteins expressed, EBV carrier cells synthesize additional EBNAs and at least one LMP (latent membrane protein 1). The latent KSHV carrier cells, in addition to LANA1, may express a viral cyclin, a viral Fas-DD-like ICE inhibitor protein (vFLIP) and a virus-specific transformation protein called kaposin (K12). In MHV latency with a wide expression of latency-associated proteins, the carrier cells express a LANA analogue (ORF73), the M3 protein, the K3/IE (immediate early) proteins and M11/bcl-2 homologue proteins. During the period of limited gene expression, the latency-associated proteins serve mainly for the maintenance of the latent episomal DNA (a typical example is EBNA1). In contrast, during latency with a broader spectrum gene expression, the virus-encoded products activate transcription of otherwise silenced cellular genes, which leads to the synthesis of enzymes capable of promoting not only viral but also cellular DNA replication. Thus, the latency-associated proteins block apoptosis and drive host cells towards division and immortalization. Proliferation of hemopoetic cells, which had become gamma herpesvirus DNA carriers, can be initiated and strongly enhanced in the presence of inflammatory cytokines and by virus-encoded analogues of interleukins, chemokines and IFN regulator proteins. At early stages of tumor formation, many proliferating hemopoetic and/or endothelium cells, which had became transcriptionally active under the influence of chemokines and cytokines, may not yet be infected. In contrast, at later stages of oncogenesis, the virus-encoded proteins, inducing false signaling and activating the proliferation pathways, bring the previously infected cells into full transformation burst.

Molecular pathology parameters in human nasopharyngeal carcinoma

BACKGROUND

To derive a better understanding of the biologic behavior of nasopharyngeal carcinoma (NPC), the authors evaluated a number of molecular variables to address the hypothesis that p53 dysfunction in NPC is associated with Epstein-Barr virus (EBV), increased tumor angiogenesis, lower likelihood of apoptosis, and poorer clinical outcome.

MATERIALS

The biopsy samples from 87 NPC patients were obtained and sections were made to detect EBV, using in-situ hybridization; the authors used immunohistochemistry to assess p53, p21(WAF1/CIP1) expression, and microvessel density count (MVD). In situ end labelling was used to evaluate apoptosis and necrosis. Analyses were conducted on the association between each of these variables as well as clinical outcome, including survival and local control.

RESULTS

There was a highly significant association between EBV-encoded RNA (EBER) positivity with p53 over-expression in that only 1 out of 32 p53 over-expressing tumors was EBER negative, as opposed to 19 out of 48 p53 negative tumors being EBER negative (P = 0.001). In addition, EBER positivity was highly associated with World Health Organization (WHO) type 3 NPC, Asian/Chinese ethnicity, a lower apoptotic index, and p21 over-expression. p53 over-expression was associated with a higher MVD count. Controlling for age and nodal status, EBER positivity was associated with both improved overall survival (P = 0.02), and disease-free survival (P = 0.04). In contrast, the presence of tumor necrosis was associated with an inferior local control (P = 0.03).

CONCLUSION

p53 protein was over-expressed in approximately one third of NPC samples in the current study, and this correlated significantly with the presence of EBER. Epstein-Barr virus status was also associated with WHO type 3 NPC, Asian/Chinese ethnicity, and induction of p21. The presence of EBV appeared to predict for improved survival, the mechanism of which remains to be elucidated in this biologically complex disease.

Coupled particle light scattering: a new technique for serodiagnosis of Epstein-Barr virus infection

The Coupled Particle Light Scattering technique was evaluated for serological diagnosis of Epstein-Barr Virus (EBV) infection. Two hundred ninety-six patient sera selected from several clinical categories (acute infection, non-primary infection, interfering non-EBV infection, non-infected) were tested for IgM and IgG antibodies (anti-VCA, anti-EBNA and anti-EA). Determination of EBV IgG with Copalis multiplex was accurate when compared with Enzygnost Anti-EBV/IgG ELISA. Although the sensitivity of Copalis IgM for acute infections was 100% a positive IgM result did not always indicate an acute infection. Strong reactivity to IgG EA (ratio 3, 1) and IgG VCA (ratio 13, 3) correlated with persistent infection or reactivation. The CopalisI has many advantages over the existing methods, such as the possibility to measure three semi-quantitative IgG responses to three different EBV antigens simultaneously.

Cytochrome P450 2E1 polymorphism and nasopharyngeal carcinoma development in Thailand: a correlative study

BACKGROUND

Nasopharyngeal carcinoma (NPC) is a rare tumor in most parts of the world but occurs at relatively high frequency among people of Chinese descent. The cytochrome P450 2E1 enzyme (CYP2E1) is responsible for the metabolic activation of nitrosamines, and has been shown to be a susceptibility gene for NPC development in Taiwan [RR = 2.6; 95%CI = 1.2-5.7]. Since there has been only one report of this link, it was decided to investigate the susceptibility of CYP2E1 to NPC development in other populations. Therefore, the correlation between the RsaI polymorphism of this gene and NPC was studied in-patients including Thai and Chinese in Thailand. The present study comprised 217 cases diagnosed with NPC and 297 healthy controls.

RESULTS

Similar to the result found in Taiwanese, a homozygous uncut genotype demonstrated a higher relative risk both when all cases were analyzed [RR = 2.19; 95%CI = 0.62-8.68] or individual racial groups, Thai [RR = 1.51; 95%CI = 0.08-90.06] or Chinese [RR = 1.99; 95%CI = 0.39-10.87]. The ethnicity-adjusted odds ratio is 2.39 with 95%CI, 0.72-7.89.

CONCLUSIONS

Though our finding was not statistically significant due to the moderate sample size of the study, similarity to the study in Taiwan with only a slight loss in precision was demonstrated. The higher RR found for the same genotype in distinct populations confirmed that CYP2E1 is one of several NPC susceptibility genes and that the RsaI minus variant is one mutation that affects phenotype.

Poor prognosis in nasopharyngeal cancer patients with low glucose-6-phosphate-dehydrogenase activity

Nasopharyngeal carcinoma (NPC) is endemic among well-defined ethnic groups in several world regions, such as Southeastern China and Taiwan. Glucose-6-phosphate-dehydrogenase (G6PD)- deficiency, a sex-linked disorder, is one of the most common enzymopathies in Taiwan. The major role of G6PD is to generate NADPH to protect cells from oxidative damage, which is a major contributing factor to certain degenerative diseases, such as aging and cancer. In view of the coincidence of epidemic distribution of NPC and G6PD deficiency, as well as the house-keeping function of G6PD in cellular oxidative defense, we investigated the correlation of G6PD activity with NPC. The stage of NPC was classified by AJCC (1997) criteria. G6PD levels were determined in 108 NPC male patients and 75 healthy male individuals. The mean G6PD level of NPC patients was 218.9 U/10(12) RBC or 7.53 U/g hemoglobin (Hb), being much lower than in normal individuals (260.6 U/10(12) erythrocytes (RBC) or 8.92 U / gHb). The level of G6PD activity had no correlation with tumor stage or lymph node or distant metastasis, but was significantly correlated with tumor recurrence (P = 0.004 when using G6PD = 130 U/10(12) RBC as cutoff value). These results indicated that low G6PD activity in patients with NPC is associated with poor prognosis.

The aetiology of nasopharyngeal carcinoma

Nasopharyngeal carcinoma is a disease with a remarkable racial and geographical distribution. In most parts of the world it is a rare condition and in only a handful of places does this low risk profile alter. These include the Southern Chinese, Eskimos and other Arctic natives, inhabitants of South-East Asia and also the populations of North Africa and Kuwait.

Telomerase activity is frequently found in metaplastic and malignant human nasopharyngeal tissues

Telomerase is a specialized ribonucleoprotein polymerase that directs the synthesis of telomere repeats at chromosome ends. Accumulating evidence has indicated that telomerase is stringently repressed in normal human somatic tissues but reactivated in cancers and immortal cells, suggesting that reactivation of telomerase plays an important role in carcinogenesis. In this study, the status of telomerase activity in diseased human nasopharyngeal lesions was determined by the telomeric repeat amplification protocol (TRAP). Fifty-four patients participated including 17 inflammation or hyperplasia, eight with squamous metaplasia, and 29 with different stages of carcinomas. Telomerase activity was detected in 1 of 17 (5.9%) inflammatory or lymphoid hyperplastic tissues, 3 of 8 (37.5%) squamous metaplastic, and 25 of 29 (86.2%) carcinoma tissues. The differences in telomerase expression in these groups is statistically significant (P < 0.001). Levels of telomerase activity correlated with tumour stage (P = 0.024). These results suggest that telomerase reactivation plays a role in the carcinogenesis of nasopharyngeal cancer. Since telomerase activity is found in the majority of nasopharyngeal cancers and a subset of metaplasia, this enzyme may be served as a reference to monitoring the status of abnormal nasopharyngeal tissues.

Alterations on chromosome 3 in endemic and nonendemic nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is endemic in parts of southern China and is etiologically associated with Epstein-Barr virus (EBV) infection as well as other dietary and environmental factors. Loss of heterozygosity (LOH) on chromosome 3p has been described in NPC from the endemic region. In this study, tumors originating from both the NPC nonendemic area of northern China and the endemic area in southern China were analyzed for LOH at 8 microsatellite markers on chromosome 3. Allele loss was detected at D3S1300 in 3p14.2 in more than 50% of tumors from both the endemic and nonendemic areas, suggesting that LOH at this locus probably does not account for the endemicity of NPC in southern China. The 3p14.2 region encompasses FHIT, a candidate tumor suppressor gene previously shown to be rearranged in several NPC cell lines. In this study, analysis of FHIT gene structure and transcription in primary tumors did not support a role for FHIT in NPC. However, the high frequency of allele loss at 3p14.2 in NPC from endemic and nonendemic regions supports the possibility that an important tumor suppressor gene other than FHIT complements EBV transformation and resides in this region.

Epstein-barr virus-associated malignancies: epidemiologic patterns and etiologic implications

Epstein-Barr virus (EBV), a ubiquitous B-lymphotrophic herpesvirus, has been found in the tumor cells of a heterogeneous group of malignancies (Burkitt's lymphoma, lymphomas associated with immunosuppression, other non-Hodgkin's lymphomas, Hodgkin's disease, nasopharyngeal carcinoma, gastric adenocarcinoma, lymphoepithelioma-like carcinomas, and immunodeficiency-related leiomyosarcoma). As the epidemiologic characteristics of these cancers have not been considered together, this review seeks to relate their incidence patterns and risk factors to EBV biology and virus-host interaction in an attempt to help elucidate factors involved in EBV-related carcinogenesis. We include a brief review of EBV virology and primary infection to provide a biologic context for considering the epidemiology, summarize the most salient epidemiologic features of each malignancy, synthesize epidemiologic data by risk factor to uncover commonalities and informative contrasts across the diseases, and propose hypotheses regarding etiologic mechanisms, based on the possible effect of the risk factors at various stages in the viral life cycle.

Detection of recurrent chromosomal gains and losses in primary nasopharyngeal carcinoma by comparative genomic hybridisation

Nasopharyngeal carcinoma (NPC) is a common cancer in Southern China but rare in Western countries. To search for genetic alterations in NPC, we examined a series of 20 primary tumours with comparative genomic hybridisation. The identified common chromosomal alterations included gain of chromosomes 1q, 8, 12, 19 and 20 as well as loss of chromosomes 1p, 3p, 9p, 9q, 11q, 13q, 14q and 16q. In concordance with our previous loss of heterozygosity studies in primary NPC, a high incidence of loss was detected on chromosomes 3p (75%), 11q (70%) and 14q (65%). Losses of 9q (60%), 13q (50%) and 16q (40%) were also identified. Novel chromosomal gains were observed on chromosome 12, with a high frequency (70%). Current analysis has revealed a comprehensive profile of the chromosomal regions showing losses and gains in primary NPC. Our findings may provide an entry point for conducting further investigations to locate the putative tumour-suppresser genes and oncogenes that may be involved in the tumourigenesis of NPC.

Human papillomavirus may be common within nasopharyngeal carcinoma of Caucasian Americans: investigation of Epstein-Barr virus and human papillomavirus in eastern and western nasopharyngeal carcinoma using ligation-dependent polymerase chain reaction

BACKGROUND

Nasopharyngeal carcinoma (NPC), particularly those tumors endemic to the Far East, commonly harbor Epstein-Barr virus (EBV), thought to serve as an important oncogenic promoter. Human papillomavirus (HPV) is associated with a proportion of upper aerodigestive tract carcinomas. We hypothesized that HPV might also contribute to the pathogenesis of NPC, and we queried whether geographic and racial distinctions may be identified between NPC of the Far East versus those diagnosed in Caucasian American patients with regard to the interrelationship of histologic subtype and viral infection.

MATERIALS AND METHODS

Formalin-fixed paraffin-embedded tissue (FFPET) from 30 patients (6 Caucasian Americans, 1 Chinese American, 14 and 9 patients from Korea and China, respectively) were studied using the ligation-dependent polymerase chain reaction (LD-PCR). These cases were histologically classified according to the World Health Organization (WHO) schema for NPC. Consensus target probes complementary to the L1 region of over 30 HPV types, as well as target probes complementary to EBER-1 (EBV-related nontranslated latency-associated RNA), were used to amplify target sequences.

RESULTS

Seven of 30 NPC (23%) contained HPV sequences. There were 6 Caucasian American patients with NPC; 3 cases (50%) were HPV positive (HPV+). Two of these Caucasian Americans had WHO type I tumors: one was HPV+ and EBV negative (EBV-) and the other was HPV-/EBV+. The remaining Caucasian American NPCs were WHO-II/III tumors which tested as follows: two were coinfected with HPV and EBV, the other two contained EBER but not HPV sequences. The single Oriental American patient had a WHO-III NPC which was HPV-/EBV+. Of the Eastern NPC patients, 4 (1 WHO-I, 3 WHO-II/III) of 23 (17%) NPCs contained HPV sequences as well as EBV. Conclusion. Human papillomavirus appears to be uncommonly (17%) associated with NPC in patients from the Far East and was detected more often (50%) in NPC from American Caucasian patients. Some of these tumors conformed to our perceptions and expectations of NPC (eg, WHO-I tumors being EBV-/HPV+ and WHO-III tumors being EBV+/HPV-), but other tumors did not conform to these expectations (eg, WHO-III NPC occasionally harboring both HPV and EBV). There appears to be a broad profile in the relationship between HPV, EBV, and NPC histologic subtype. Unfortunately, the number of American Caucasian cases studied are too small to allow for strong conclusions.

Carcinoma of the nasopharynx

Nasopharyngeal carcinoma (NPC) is an intriguing disease that shows a distinct geographical distribution with well-defined, high-risk ethnic groups. This neoplasm exhibits strong associations with the Epstein-Barr virus, dietary and genetic factors. Radiation therapy is the mainstay of treatment and imaging plays a central role in tumor mapping and radiation therapy planning. NPC provides an excellent model for the study of normal and pathological anatomy of the skull base. It also provides an excellent model in the study of consequences of radiation therapy.

Chromosomal abnormalities of a new nasopharyngeal carcinoma cell line (NPC-BM1) derived from a bone marrow metastatic lesion

An epithelial cell line, NPC-BM1, was established from a bone marrow biopsy of a female Taiwanese patient with nasopharyngeal carcinoma (NPC). Histopathology of the bone marrow biopsy and xenografts grown in severe combined immunodeficiency mice showed that the tumor was a nonkeratinizing, poorly differentiated carcinoma. NPC-BM1 cells grown as monolayers had a doubling time of 28.5 hours. Chromosome analysis showed that NPC-BM1 had the following features: 1) hypotetraploidy with a modal chromosome number of 87 (84-90); 2) numerically and structurally normal chromosomes 18; 3) numerical abnormalities without apparent structural alterations on chromosomes 14, 16, 17, 19, and 20; 4) ten structural abnormalities, t(1;9)(p11;q11), t(3;?;4)(p13;?;q13), add(4p),del(6p), i(8) [corrected] (q10),der(?)t(?;12),(?;p12),[corrected] add(21)(p11), del(X)(q24), add(X)(q22), and marker 1 (M1), in all metaphases examined, which were found to be present in two to five cell lines from primary NPC tumors reported previously; and 5) four other abnormalities, t(2;?;2)(p11.2;?;q21),t(11;22)(q11;q11),i(22)(q10), and marker 2 (M2), unique to this metastatic cell line. To the best of our knowledge, NPC-BM1 is the first NPC cell line derived from a distant metastatic site. Further evaluation of this cell line and additional metastatic NPC cell lines as well as primary NPC cell lines with respect to relations between the timing, karyotypic anomalies, and immunobiological characteristics in NPC progression and metastasis is warranted.

Lymphoepithelioma-like carcinoma of the uterine cervix: association with Epstein-Barr virus and human papillomavirus

BACKGROUND

The presence of Epstein-Barr virus (EBV) has not been documented in previous reports of lymphoepithelioma-like carcinoma (LELC) of the uterine cervix by either polymerase chain reaction or in situ hybridization, and the histogenesis of the tumor remains unknown. Additionally, a relationship between human papillomavirus (HPV) and cervical LELC also has not been reported.

METHODS

In this article, the authors describe the clinical and histopathologic findings for 15 patients with cervical carcinoma that had a histologic pattern of LELC. The polymerase chain reaction detected the presence of EBV and HPV DNA sequences in cervical LELC.

RESULTS

All 15 tumors showed a typical syncytial growth pattern of undifferentiated cells with prominent lymphocytic infiltration. The detection rate of the EBV gene sequence in tissue samples from patients with LELC was more frequent than that in control patients with squamous cell carcinoma of the cervix (11 of 15 patients, 73.3%, vs. 4 of 15 patients, 26.7%; P = 0.01). However, the detection rate of HPV-16 and HPV-18 DNA was significantly lower in patients with LELC tumors than in patients with cervical squamous cell carcinoma (3 of 15 patients, 20.0%, vs. 12 of 15 patients, 80.0%; P = 0.001). After a median follow-up of 3.9 years (range, 1.8-5.3 years), the 15 patients showed no evidence of disease or metastasis after radical hysterectomy or radiotherapy.

CONCLUSIONS

The finding of EBV associations in cervical LELC supports the hypothesis that EBV may be involved in the pathogenesis of tumors that arise in the cervix. It is possible that cervical LELC may follow a different pathway in the pathogenesis of LELC in Asian women as compared with the more common forms of squamous cell carcinoma.

Nasopharyngeal carcinoma, with emphasis on its relationship to Epstein-Barr virus

Nasopharyngeal carcinoma (NPC) is an epithelial tumor with a distinct geographic distribution and characteristic histologic appearance. It is rare in Europe and North America, but it is among the most common cancers in southern China. Genetic predisposition, environmental factors, and Epstein-Barr virus (EBV) all have been associated with the pathogenesis of this tumor. There is an increasing body of evidence that among all these factors, EBV appears to be the strongest and most consistently related factor. According to the current sensitive in situ hybridization methods for the detection of EBV-encoded small RNAs (EBER), almost 100% of cases of NPC, irrespective of their histologic subtypes, have demonstrable EBERs in the nuclei of the tumor cells. In this review paper, we discuss the predisposing genetic and environmental factors and the role of EBV in the pathogenesis of this tumor with particular emphasis on the role of EBV.

Deletions of the short arm of chromosome 3 in solid tumors and the search for suppressor genes

The concept that cells can become malignant upon the elimination of parts of chromosomes inhibiting cell division dates back to Boveri in 1914. Deletions occurring in tumor cells are therefore considered a first indication of possible locations of tumor suppressor gene. Approaches used to localize and identify the paradigm of tumor suppressors, RB1, have also been applied to localize tumor suppressor genes on 3p, the short arm of chromosome 3. This review discusses the methodological advantages and limitations of the various approaches. From a review of the literature on losses of 3p in different types of solid tumors it appears that some tumor types show involvement of the same region, while between others the regions involved clearly differ. Also discussed are results of functional assays of tumor suppression by transfer of part of chromosome 3 into tumor cell lines. The likelihood that a common region of deletions would contain a tumor suppressor is strongly enhanced by coincidence of that region with a chromosome fragment suppressing tumorigenicity upon introduction in tumor cells. Such a situation exists for a region in 3p21.3 as well as for one or more in 3p12-p14. The former region is considered the location of a lung cancer suppressor. The same gene or a different one in the same region may also play a role in the development of other cancers including renal cell cancer. In the latter cancer, there may be additional roles of the VHL region and/or a 3p12-p14 region. The breakpoint region of a t(3;8) originally found to be constitutively present in a family with hereditary renal cell cancer now seems to be excluded from such a role. Specific genes on 3p have been suggested to act as suppressor genes based on either their location in a common deletion region, a markedly reduced expression or presence of aberrant transcripts, their capacity to suppress tumorigenicity upon transfection in to tumor cells, the presumed function of the gene product, or a combination of several of these criteria. A number of genes are evaluated for their possible role as a tumor suppressor according to these criteria. General agreement on such a role seems to exist only for VHL. Though hMLH1 plays an obvious role in the development of specific mismatch repair-deficient cancers, it cannot revert the tumor phenotype and therefore cannot be considered a proper tumor suppressor. The involvement of VHL and MLH1 also in some specific hereditary cancers allowed to successfully apply linkage analysis for their localization. TGFBR2 might well have a tumor suppressor function. It does reduce tumorigenicity upon transfection. Other 3p genes coding for receptor proteins THRB and RARB, are unlikely candidates for tumor suppression. Present observations on a possible association of FHIT with tumor development leave a number of questions unanswered, so that provisionally it cannot be considered a tumor suppressor. Regions that have been identified as crucial in solid tumor development appear to be at the edge of synteny blocks that have been rearranged through the chromosome evolution which led to the formation of human chromosome 3. Although this may merely represent a chance occurrence, it might also reflect areas of genomic instability.

Genomic alterations in nasopharyngeal carcinoma: loss of heterozygosity and Epstein-Barr virus infection

Nasopharyngeal carcinoma is a subset of head and neck squamous cell cancers with unique endemic distribution and aetiological co-factors. Epstein-Barr virus has been revealed to be an important aetiological factor for most nasopharyngeal carcinomas. Nevertheless, additional genetic alterations may be involved in their development and progression. The aim of this study was to determine the likely chromosomal locations of tumour-suppressor genes related to Epstein-Barr virus-associated nasopharyngeal carcinoma. Fifty-six microsatellite polymorphic markers located on every autosomal arm were used to estimate the incidence of loss of heterozygosity in 27 Epstein-Barr virus-associated nasopharyngeal carcinomas. High frequencies of allelic loss were observed on chromosome 3p (75.0%) and 9p (87.0%). Chromosome 9q, 11q, 13q and 14q displayed loss in over 50%, while chromosome 3q, 6p, 16q, 19q and 22q exhibited loss in 35-50%. Furthermore, several other chromosomal arms demonstrated allelic loss in 20-35%. Additionally, 1 of the 27 cases showed microsatellite instability at multiple loci. These findings provide evidence of multiple genetic alterations during cancer development and clues for further studies of tumour-suppressor genes in Epstein-Barr virus-associated nasopharyngeal carcinoma.

Major role for a 3p21 region and lack of involvement of the t(3;8) breakpoint region in the development of renal cell carcinoma suggested by loss of heterozygosity analysis

In a loss of heterozygosity analysis of 3p, we examined 44 sporadic cases of renal cell carcinoma (RCC) and matched normal tissue with 18 markers distributed over the whole p-arm. The majority of these markers clustered in three regions that have been suggested to be involved in the development of RCC, namely the p25 region, where the von Hippel Lindau (VHL) gene is located; the p21 region, which has been identified as a common region of overlap (SRO) of heterozygous deletions; and the p14 region, which is the location of the constitutional t(3;8) breakpoint occurring in an RCC family. Thirty-one out of these 44 tumors were analyzed with 9 additional markers from the 3p12-14 region to further delimit the SRO in this region. Our analysis shows that when deletions were detected the 3p21 region was always included. The 3p21 markers D3F15S2 and UBEIL were always contained within these 3p21 deletions. The t(3;8) breakpoint region showed the lowest percentage of loss of heterozygosity. Moreover, in three cases the t(3;8) breakpoint region retained heterozygosity, whereas a region more proximal to the breakpoint showed allelic losses. This supports exclusion of the t(3;8) region from a role in the development of sporadic RCC. In a number of tumors, two or three 3p regions with allelic losses were present separated by a region of retention of heterozygosity. In these tumors, deletions at 3p21 occurred in combination with deletions of either the VHL region, or the region proximal to the t(3;8), or both, suggestive of multiple gene involvement in the development of sporadic RCC with a primary role of the 3p21 region.

YAC contigs covering an 8-megabase region of 3p deleted in the small-cell lung cancer cell line U2020

Somatic deletions of chromosome 3p occur at high frequencies in cancers of kidney, breast, cervix, head and neck, nasopharynx, and lung. The frequency of 3p deletion in lung cancer approaches 100% among small cell lesions and 70 to 80% in non-small cell lesions. This evidence strongly implies that one or more tumor suppressor genes of potentially widespread significance reside within the deleted region(s). Precise definition of the deleted target region(s) has been difficult due to the extensive area(s) lost and use of markers with low informativeness. However, improved definition remains essential to permit isolation of putative tumor suppressor genes from 3p. The identification of several small, homozygous 3p deletions in lung cancer cell lines has provided a critical resource that will assist this search. The U2020 cell line contains a small homozygous deletion that maps to a very proximal region of 3p and includes the marker D3S3. We previously identified a subset of DNA markers located within the deleted region and determined their relative order by pulsed-field gel mapping studies. In the present report, we describe the development of YAC contigs that span the majority of the deleted region and link up to flanking markers on both sides. The centromere proximal portion of the contig crosses the breakpoint from an X;3 translocation located within 3p12 providing both location and orientation to the map. PCR-based (CA)n microsatellite polymorphisms have been localized within and flanking the deletion region. These markers should greatly facilitate loss-of-heterozygosity studies of this region in human cancer. The contig provides a direct means for isolation of putative tumor suppressor genes from this segment of 3p.

The biology and pathology of selected skull base tumors

This paper describes the pathobiology of some of the more common skull base tumors. In addition to clinicopathologic features, emphasis is placed upon methods of diagnosis utilizing immunoperoxidase stains and molecular markers that may or may not impact upon prognosis.

Cytogenetics of cranial base tumors

Many different tumor types can arise in or invade the skull base. The more common tumors include, but are not limited to, angiofibromas, chondrosarcomas, chordomas, hemangiopericytomas, meningiomas, carcinomas, olfactory neuroblastomas, paragangliomas, pituitary adenomas, and rhabdomyosarcomas. Several of these tumors, including meningiomas, hemangiopericytomas, and rhabdomyosarcomas are characterized by nonrandom cytogenetic abnormalities. In this paper, we review the recognized chromosomal aberrations in cranial base tumors and illustrate the insights that can be gained into the genetic basis of tumor formation using karyotypes from skull base tumors that we have examined. As in tumors in other locations, chromosomal findings may be of diagnostic and prognostic value in cranial base tumors.