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

Virus-specific T-cells from third party or transplant donors for treatment of EBV lymphoproliferative diseases arising post hematopoietic cell or solid organ transplantation

EBV+ lymphomas constitute a significant cause of morbidity and mortality in recipients of allogeneic hematopoietic cell (HCT) and solid organ transplants (SOT). Phase I and II trials have shown that in HCT recipients, adoptive transfer of EBV-specific T-cells from the HCT donor can safely induce durable remissions of EBV+ lymphomas including 70->90% of patients who have failed to respond to treatment with Rituximab. More recently, EBV-specific T-cells generated from allogeneic 3rd party donors have also been shown to induce durable remission of EBV+ lymphomas in Rituximab refractory HCT and SOT recipients. In this review, we compare results of phase I and II trials of 3rd party and donor derived EBV-specific T-cells. We focus on the attributes and limitations of each product in terms of access, safety, responses achieved and durability. The limited data available regarding donor and host factors contributing to T cell persistence is also described. We examine factors contributing to treatment failures and approaches to prevent or salvage relapse. Lastly, we summarize strategies to further improve results for virus-specific immunotherapies for post-transplant EBV lymphomas.

Radiosensitivity-Related Genes and Clinical Characteristics of Nasopharyngeal Carcinoma

Materials and Methods

Clinicopathological data of 185 patients with NPC treated at Nanfang Hospital of Southern Medical University between January 2013 and December 2014 were retrospectively analyzed. SPSS statistical software was used to analyze the clinicopathological data related to radiotherapy efficacy. Three patients who achieved complete remission and three with disease progression after CRT were selected. Differentially expressed genes (DEGs) were screened via mRNA microarray analysis of primary diagnostic endoscopy specimens.

Results

The peripheral blood leukocyte count, platelet count, and EBV-DNA copy number in NPC patients who were resistant to radiotherapy were higher than those in NPC patients who were sensitive to radiotherapy. The RobustRankAggreg (RRA) analysis method identified 392 DEGs, and the 66 most closely related genes among the DEGs were identified from the PPI network.

Conclusion

The results of this study indicate that screening for DEGs and pathways in NPC using integrated in silico analyses can help identify a series of genetic and clinical signatures for NPC patients treated with neoadjuvant chemotherapy followed by concurrent chemoradiotherapy.

Epstein-Barr virus BALF3 mediates genomic instability and progressive malignancy in nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is a head and neck cancer prevalent throughout Southern China and Southeast Asia. Patient death following relapse after primary treatment remains all too common but the cause of NPC relapse is unclear. Clinical and epidemiological studies have revealed the high correlation among NPC development, Epstein-Barr virus (EBV) reactivation and host genomic instability. Previously, recurrent EBV reactivation was shown to cause massive genetic alterations and enhancement of tumor progression in NPC cells and these may be required for NPC relapse. Here, EBV BALF3 has the ability to induce micronuclei and DNA strand breaks. After recurrent expression of BALF3 in NPC cells, genomic copy number aberrations, determined by array-based comparative genomic hybridization, had accumulated to a significant extent and tumorigenic features, such as cell migration, cell invasion and spheroid formation, increased with the rounds of induction. In parallel experiments, cells after highly recurrent induction developed into larger tumor nodules than control cells when inoculated into NOD/SCID mice. Furthermore, RNA microarrays showed that differential expression of multiple cancer capability-related genes and oncogenes increased with recurrent BALF3 expression and these changes correlated with genetic aberrations. Therefore, EBV BALF3 is a potential factor that mediates the impact of EBV on NPC relapse.

Characterization of NOL7 gene point mutations, promoter methylation, and protein expression in cervical cancer

NOL7 is a putative tumor suppressor gene localized to 6p23, a region with frequent loss of heterozygosity in a number of cancers, including cervical cancer (CC). We have previously demonstrated that reintroduction of NOL7 into CC cells altered the angiogenic phenotype and suppressed tumor growth in vivo by 95%. Therefore, to understand its mechanism of inactivation in CC, we investigated the genetic and epigenetic regulation of NOL7. NOL7 mRNA and protein levels were assessed in 13 CC cell lines and 23 consecutive CC specimens by real-time quantitative polymerase chain reaction, western blotting, and immunohistochemistry. Methylation of the NOL7 promoter was analyzed by bisulfite sequencing and mutations were identified through direct sequencing. A CpG island with multiple CpG dinucleotides spanned the 5' untranslated region and first exon of NOL7. However, bisulfite sequencing failed to identify persistent sites of methylation. Mutational sequencing revealed that 40% of the CC specimens and 31% of the CC cell lines harbored somatic mutations that may affect the in vivo function of NOL7. Endogenous NOL7 mRNA and protein expression in CC cell lines were significantly decreased in 46% of the CC cell lines. Finally, immunohistochemistry demonstrated strong NOL7 nucleolar staining in normal tissues that decreased with histologic progression toward CC. NOL7 is inactivated in CC in accordance with the Knudson 2-hit hypothesis through loss of heterozygosity and mutation. Together with evidence of its in vivo tumor suppression, these data support the hypothesis that NOL7 is the legitimate tumor suppressor gene located on 6p23.

The synergistic effect of chemical carcinogens enhances Epstein-Barr virus reactivation and tumor progression of nasopharyngeal carcinoma cells

Seroepidemiological studies imply a correlation between Epstein-Barr virus (EBV) reactivation and the development of nasopharyngeal carcinoma (NPC). N-nitroso compounds, phorbols, and butyrates are chemicals found in food and herb samples collected from NPC high-risk areas. These chemicals have been reported to be risk factors contributing to the development of NPC, however, the underlying mechanism is not fully understood. We have demonstrated previously that low dose N-methyl-N’-nitro-N-nitrosoguanidine (MNNG, 0.1 µg/ml) had a synergistic effect with 12-O-tetradecanoylphorbol-13-acetate (TPA) and sodium butyrate (SB) in enhancing EBV reactivation and genome instability in NPC cells harboring EBV. Considering that residents in NPC high-risk areas may contact regularly with these chemical carcinogens, it is vital to elucidate the relation between chemicals and EBV and their contributions to the carcinogenesis of NPC. In this study, we constructed a cell culture model to show that genome instability, alterations of cancer hallmark gene expression, and tumorigenicity were increased after recurrent EBV reactivation in NPC cells following combined treatment of TPA/SB and MNNG. NPC cells latently infected with EBV, NA, and the corresponding EBV-negative cell, NPC-TW01, were periodically treated with MNNG, TPA/SB, or TPA/SB combined with MNNG. With chemically-induced recurrent reactivation of EBV, the degree of genome instability was significantly enhanced in NA cells treated with a combination of TPA/SB and MNNG than those treated individually. The Matrigel invasiveness, as well as the tumorigenicity in mouse, was also enhanced in NA cells after recurrent EBV reactivation. Expression profile analysis by microarray indicates that many carcinogenesis-related genes were altered after recurrent EBV reactivation, and several aberrations observed in cell lines correspond to alterations in NPC lesions. These results indicate that cooperation between chemical carcinogens can enhance the reactivation of EBV and, over recurrent reactivations, lead to alteration of cancer hallmark gene expression with resultant enhancement of tumorigenesis in NPC.

Biomarkers for use in monitoring responses of nasopharyngeal carcinoma cells to ionizing radiation

Nasopharyngeal carcinoma (NPC) is a common head and neck cancer. The incidence rate is higher in southern China and Southeast Asia in comparison with the Western countries. Radiotherapy is the standard treatment of NPC as the cancer cells are sensitive to ionizing radiation. Radiation treatment has good local control to patients with early NPC. It is essential to monitor the response of the NPC cells to radiation treatment in advance in order to select suitable treatment choice for the patients. This review aims to discuss the potential use of biomarkers in monitoring the responsiveness of NPC cells to radiation treatment.

Anti-angiogenic and tumor-suppressive roles of candidate tumor-suppressor gene, Fibulin-2, in nasopharyngeal carcinoma

Fibulin-2 (FBLN2) has been identified as a candidate tumor-suppressor gene in nasopharyngeal carcinoma (NPC). Originally identified through a chromosome 3 NotI genomic microarray screen, it shows frequent deletion or methylation in NPC. FBLN2 is located on chromosome 3p25.1 and is associated with tumor development through its important interactions with the extracellular matrix (ECM) proteins. FBLN2 encodes two isoforms. The short isoform (FBLN2S) is expressed abundantly in normal tissues, but is dramatically downregulated in NPC, while the long isoform (FBLN2L) is either not detectable or is expressed only at low levels in both normal and tumor tissues. Reintroduction of this FBLN2S inhibited cell proliferation, migration, invasion and angiogenesis in vitro. Furthermore, in vivo studies in nude mice show its expression is associated with tumor and angiogenesis suppression. FBLN2-associated angiogenesis occurs via concomitant downregulation of vascular endothelial growth factor and matrix metalloproteinase 2. This study provides compelling evidence that FBLN2S has an important tumor-suppressive and anti-angiogenic role in NPC.

Identification and functional analysis of NOL7 nuclear and nucleolar localization signals

BACKGROUND

NOL7 is a candidate tumor suppressor that localizes to a chromosomal region 6p23. This locus is frequently lost in a number of malignancies, and consistent loss of NOL7 through loss of heterozygosity and decreased mRNA and protein expression has been observed in tumors and cell lines. Reintroduction of NOL7 into cells resulted in significant suppression of in vivo tumor growth and modulation of the angiogenic phenotype. Further, NOL7 was observed to localize to the nucleus and nucleolus of cells. However, the mechanisms regulating its subcellular localization have not been elucidated.

RESULTS

An in vitro import assay demonstrated that NOL7 requires cytosolic machinery for active nuclear transport. Using sequence homology and prediction algorithms, four putative nuclear localization signals (NLSs) were identified. NOL7 deletion constructs and cytoplasmic pyruvate kinase (PK) fusion proteins confirmed the functionality of three of these NLSs. Site-directed mutagenesis of PK fusions and full-length NOL7 defined the minimal functional regions within each NLS. Further characterization revealed that NLS2 and NLS3 were critical for both the rate and efficiency of nuclear targeting. In addition, four basic clusters within NLS2 and NLS3 were independently capable of nucleolar targeting. The nucleolar occupancy of NOL7 revealed a complex balance of rapid nucleoplasmic shuttling but low nucleolar mobility, suggesting NOL7 may play functional roles in both compartments. In support, targeting to the nucleolar compartment was dependent on the presence of RNA, as depletion of total RNA or rRNA resulted in a nucleoplasmic shift of NOL7.

CONCLUSIONS

These results identify the minimal sequences required for the active targeting of NOL7 to the nucleus and nucleolus. Further, this work characterizes the relative contribution of each sequence to NOL7 nuclear and nucleolar dynamics, the subnuclear constituents that participate in this targeting, and suggests a functional role for NOL7 in both compartments. Taken together, these results identify the requisite protein domains for NOL7 localization, the kinetics that drive this targeting, and suggest NOL7 may function in both the nucleus and nucleolus.

N-methyl-N'-nitro-N-nitrosoguanidine induces and cooperates with 12-O-tetradecanoylphorbol-1,3-acetate/sodium butyrate to enhance Epstein-Barr virus reactivation and genome instability in nasopharyngeal carcinoma cells

Seroepidemiological studies implicate a correlation between Epstein-Barr virus (EBV) reactivation and the development of nasopharyngeal carcinoma (NPC). Moreover, N-nitroso compounds are known chemical carcinogens in preserved foodstuffs and cigarettes and have been implicated as risk factors contributing to the development of NPC. Here, NPC cell lines latently infected with EBV, NA and HA, and the corresponding EBV-negative NPC cell lines, NPC-TW01 and HONE-1, were used as the model system in this study. We demonstrate that the reactivation of EBV increases with increasing concentrations of N-methyl-N'-nitro-N-nitrosoguanidine (MNNG). MNNG at a single non-toxic concentration (0.1μg/ml) did not induce discernible reactivation of EBV, but repeated treatment with this concentration of MNNG significantly induced viral reactivation. Furthermore, low dose MNNG (0.1μg/ml) had a synergistic effect with 12-O-tetradecanoylphorbol-1,3-acetate (TPA)/sodium butyrate (SB) (10ng/ml and 0.75mM, respectively) on EBV reactivation. Through promoter activity assay, MNNG was found to enhance the transcriptional activity of Rta on Rta and Zta promoters. Using siZta to block EBV reactivation, the concomitant induction of genome instability was diminished indicating that reactivation is critical for enhancing genome instability. Co-treatment with TPA/SB and MNNG markedly increased the levels of γH2AX and ROS formation in NPC cells, which may be responsible for the increase of genome instability. Our findings offer a possible mechanism by which N-nitroso compounds induce reactivation of EBV and contribute to malignant progression by enhancing genome instability in NPC cells.

The progress on genetic analysis of nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is a rare malignancy in most parts of the world, but is one of the most common cancers in Southeast Asia. Both genetic and environmental factors contribute to the tumorigenesis of NPC, most notably the consumption of certain salted food items and Epstein-Barr virus infection. This review will focus on the current progress of the genetic analysis of NPC (genetic susceptibilities and somatic alterations). We will review the current advances in genomic technologies and their shaping of the future direction of NPC research.

Functional characterization of THY1 as a tumor suppressor gene with antiinvasive activity in nasopharyngeal carcinoma

THY1 was previously identified as a candidate tumor suppressor gene (TSG) associated with lymph node metastases in nasopharyngeal carcinoma (NPC) through functional studies. It was identified by oligonucleotide microarray analysis as an interesting differentially expressed gene. However, direct functional evidence is still lacking for THY1 being a TSG in NPC, as in vivo tumorigenicity assays have not been previously reported in our last study of THY1. In this study, a tetracycline-inducible expression vector, pETE-Bsd, was used to obtain stable transfectants of THY1. The stringent in vivo tumorigenicity assay results show that the activation of THY1 suppresses tumor formation of HONE1 cells in nude mice, and the tumor formation ability was restored in the presence of doxycycline (a tetracycline analog), when the gene is shut off. Functional inactivation of this gene is observed in all the tumors derived from the tumorigenic transfectant. The tumor suppressive effect could be repressed by knockdown of THY1 expression in nontumorigenic microcell hybrids. Further studies indicate that expression of THY1 inhibits HONE1 cell growth in vitro by arresting cells in G(0)/G(1) phase. It greatly reduces the ability for anchorage-independent growth. The invasiveness of HONE1 cells was also inhibited by the expression of THY1. These findings suggest that THY1 is a TSG in NPC, which is involved in invasion and shows an association with tumor metastasis. Taken together, THY1 clearly plays an important functional role in tumor suppression in NPC.

Allelic imbalance and abnormal expression of FHIT in endemic nasopharyngeal carcinoma: association with clinicopathological features

The FHIT gene is involved in the pathogenesis of many cancers. The aim of this study was to investigate allelic imbalance (AI) pattern at FHIT locus and alteration of FHIT gene in nasopharyngeal carcinoma (NPC) and analyzed potential correlation between AI, FHIT mRNA expression and clinicopathological factors. We examined AI, including loss of heterozygosity (LOH) and microsatellite instability (MSI), at FHIT locus in 41 cases of NPC by microsatellite analysis and FHIT gene status in 30 cases of NPC by nested reverse transcriptase-polymerase chain reaction and DNA sequencing. The frequencies of LOH and MSI at FHIT locus in NPC were 70.7% (29/41) and 36.6% (15/41), respectively. Thirteen of thirty (43.3%) NPCs exhibited aberrant FHIT transcripts. LOH and abnormal FHIT expression were correlated with advanced clinical stage and higher titers of immunoglobulin (Ig) A against Epstein-Barr virus capsid antigen (EBVCA-IgA) (p < 0.05). Abnormal FHIT expression was also correlated with tumor recurrence (p < 0.05). MSI was correlated with early clinical stage and higher titers of EBVCA-IgA (p < 0.05). AI at FHIT locus is a common event and contributes to genetic imbalance in NPC. The abnormalities of FHIT, presumably associated with genetic imbalance at FHIT locus, might be involved in the development and the tumor recurrence of NPC.

Identification and characterization of the human NOL7 gene promoter

NOL7 is a candidate tumor suppressor gene that localizes to 6p23, a chromosomal region frequently associated with loss of heterozygosity in a number of malignancies including cervical cancer (CC). Re-expression of NOL7 in CC cells suppresses in vivo tumor growth by 95% and alters the angiogenic phenotype by modulating the expression of VEGF and TSP1. Here, we describe the determination of two NOL7 transcriptional start sites (TSS), the cloning of its regulatory promoter region, and the identification of transcription factors that regulate its expression. Using 5' Rapid amplification of complementary DNA ends (RACE), two transcriptional start sites were identified. Deletion analysis determined that the essential elements required for the optimal promoter activity of NOL7 were 560 bp upstream of its translation start site. In silico analysis suggested that the promoter region contained potential binding sites for the SP1, c-Myc and RXRalpha transcription factors as well as an overall GC content of greater than 60%. Chromatin immunoprecipitation (ChIP) confirmed that SP1, c-Myc and RXRalpha bound to the NOL7 promoter region. Finally, we demonstrate that NOL7 expression was positively regulated by c-Myc and RXRalpha. These results demonstrate that the NOL7 promoter region possesses each of the key elements of a TATA-less promoter. In addition, the positive regulation of NOL7 by c-Myc and RXRalpha provides additional mechanistic insights into the potential role of NOL7 in CC and other malignancies.

Independent effect of EBV and cigarette smoking on nasopharyngeal carcinoma: a 20-year follow-up study on 9,622 males without family history in Taiwan

This study aimed to assess independent effects of EBV and cigarette smoking on nasopharyngeal carcinoma, which have never been assessed in long-term follow-up studies. A cohort of 9,622 men was enrolled from 1984 to 1986. Blood samples collected at study entry were tested for antibodies against EBV antigens (anti-EBV) viral capsid antigen immunoglobulin A and DNase. The cigarette smoking habit was inquired through questionnaire interview. Newly developed nasopharyngeal carcinoma cases were ascertained through computerized linkage with national cancer registry profile. Cox's proportional hazard regression analysis was used to estimate multivariate-adjusted hazard ratio with its 95% confidence interval (95% CI). During the follow-up of 173,706 person-years, 32 pathologically confirmed nasopharyngeal carcinoma cases were identified >1 year after recruitment. Increasing serum levels of anti-EBV viral capsid antigen immunoglobulin A and DNase were significantly associated with nasopharyngeal carcinoma risk in a dose-response relationship. The multivariate-adjusted hazard ratio (95% CI) of developing nasopharyngeal carcinoma for low and high antibody levels compared with seronegatives was 9.5 (2.2-40.1) and 21.4 (2.8-161.7), respectively, for anti-EBV viral capsid antigen immunoglobulin A (P < 0.001 for trend), and 1.6 (0.5-4.6) and 16.0 (5.4-47.1), respectively, for anti-EBV DNase (P < 0.001 for trend). The shorter the time interval between study entry and nasopharyngeal carcinoma diagnosis, the higher was the proportion of anti-EBV viral capsid antigen immunoglobulin A among nasopharyngeal carcinoma patients. The multivariate-adjusted hazard ratio (95% CI) was 3.0 (1.3-7.2) for > or =30 pack-years of cumulative cigarette smoking compared with <30 pack-years as the reference. The longer and heavier the cigarette smoking habit, the higher was the nasopharyngeal carcinoma risk. Anti-EBV viral capsid antigen immunoglobulin A, anti-EBV DNase, and long-term heavy cigarette smoking are independent nasopharyngeal carcinoma risk predictors.

Promoter hypermethylation of CCNA1, RARRES1, and HRASLS3 in nasopharyngeal carcinoma

In search for putative tumor suppressor genes critical of nasopharyngeal carcinoma (NPC), we analyzed the available information from the expression profiling in conjunction with the comprehensive alleotyping published data relevant to this malignancy. Integration of this information suggested eight potential candidate tumor suppressor genes, CCNA1, HRASLS3, RARRES1, CLMN, EML1, TSC22, LOH11CR2A and MCC. However, to confirm the above observations, we chose to investigate if promoter hypermethylation of these candidate genes would be one of the mechanisms responsible for the de-regulation of gene expression in NPC in addition to the loss of genetic materials. In this study, we detected consistent hypermethylation of the 5' element of CCNA1, RARRES1, and HRASLS in NPC tissues with prevalence of 48%, 51%, and 17%, respectively. Moreover, we found a similar profile of promoter hypermethylation in primary cultured NPC cells but none in normal nasopharyngeal epithelium or leukocytes, which further substantiate our hypothesis. Our data indicate that CCNA1, RARRES1, and HRASLS3 may be the putative tumor suppressor genes in NPC.

Identification of tumor suppressive activity by irradiation microcell-mediated chromosome transfer and involvement of alpha B-crystallin in nasopharyngeal carcinoma

In previous studies, we successfully refined nasopharyngeal carcinoma (NPC) critical regions (CRs) mapping to chromosome 11q13 and 11q22-23. The chromosome 11 fragment containing the 1.8 Mb NPC CR at 11q13 (CR1), the CR at 11q22.3 mapped near D11S2000 (CR2), part of the CR at 11q23.1-11q23.2 overlapping with D11S1300 and D11S1391 (CR3), and the CR at cell adhesion molecule 1 (CADM1) locus (CR4), was chosen as the chromosome 11 donor cell line for the present study. Gamma irradiation was applied to cleave this truncated chromosome into smaller fragments and a new panel of donor cells containing further deleted fragments was produced. Subclones XMCH3.2 and XMCH3.4 were chosen for subsequent transfer to HONE1 cells; each contains a single copy of deleted chromosome 11 fragment with or without CR2 and the THY1 locus, previously shown to be involved in NPC. Both resultant chromosome 11 fragments in XMCH3.2 and XMCH3.4 caused tumor suppression. The association of alpha B-crystallin (CRYAB), a gene identified as being differentially expressed by gene profiling of NPC and an immortalized nasopharyngeal epithelial cell line, and which is located near CR3, was found to be associated with tumor suppression in all the tumor-suppressive hybrids. In addition, the expression level of this gene was down-regulated in the 7 NPC cell lines and in 5 out of 14 normal/tumor tissue pairs in the present study. Both promoter hypermethylation and allelic loss may be involved in the inactivation of this gene, suggesting its possible role in NPC development.

Genetic polymorphisms of TLR3 are associated with Nasopharyngeal carcinoma risk in Cantonese population

Background

Nasopharyngeal carcinoma is endemic in Southern China, displays a strong relationship with genetic susceptibility and associates with Epstein-Barr virus infection. Toll-like receptor 3 (TLR3) plays an important role in the antivirus response. Therefore, we examined the association between TLR3 gene polymorphisms and NPC susceptibility.

Methods

We performed a case-control study of 434 NPC cases and 512 healthy controls matched on age, sex and residence. Both cases and controls are of Cantonese origin from Southern China. Genetic variants in TLR3 were determined by polymerase chain reaction (PCR)-based DNA direct sequencing and four SNPs were genotyped in all samples.

Results

Our results showed that allele C for SNP 829A/C increased NPC risk significantly ((p = 0.0068, OR = 1.49, 95%CI:1.10–2.00). When adjusted for age, gender and VCA-IgA antibody titers, the NPC risk was reduced significantly among individuals who carried the haplotype "ATCT" compared to those who carried the most common haplotype "ACCT" (p = 0.0054, OR = 0.028; 95% CI (0.002–0.341).

Conclusion

The TLR3 polymorphisms may be relevant to NPC susceptibility in the Cantonese population, although the reduction in NPC risk is modest and the biological mechanism of the observed association merits further investigation.

Frequent allelic loss at the FRA3B site in endemic nasopharyngeal carcinoma: association with clinical features and Epstein-Barr virus infection

In this study, we aimed to precisely define the patterns of allelic loss at the FRA3B site in endemic nasopharyngeal carcinoma and to determine whether an association exists between allelic loss, clinicopathological features and Epstein-Barr virus infection. We examined the loss of heterozygosity in 40 cases of nasopharyngeal carcinoma from an endemic area in southern China, using eight high dense, polymorphic, microsatellite markers within or flanking the FRA3B site. Loss of heterozygosity at the FRA3B region was shown in 31 (77.5 per cent) primary tumours. Loss of heterozygosity was found most frequently at the D3S1300 (55.6 per cent) and D3S2757 (50.0 per cent) loci. The common area of deletion was located between the D3S4103 and D3S4260 loci. In nasopharyngeal carcinoma, loss of heterozygosity at the FRA3B/fragile histidine triad locus correlated with the following clinicopathological parameters: tumour T-stage, lymph node status, clinical stage, tumour differentiation and serum antibody titres of immunoglobulin (Ig) A against Epstein-Barr virus capsid antigen. Significantly frequent loss of heterozygosity was observed in nasopharyngeal carcinoma with tumour stages T3 and T4, lymph node metastasis and advanced tumour-node-metastasis staging (III and IV). Very frequent loss of heterozygosity was also observed to correlate with World Health Organization type III nasopharyngeal carcinoma histopathology. We also found that nasopharyngeal carcinoma patients with high titres of IgA against Epstein-Barr virus capsid antigen showed very frequent loss of heterozygosity. Allelic loss at the FRA3B site occurs significantly more commonly in endemic nasopharyngeal carcinoma patients. This suggests that the region between D3S4103 and D3S4260 may represent a preferential molecular target in nasopharyngeal carcinogenesis.

The enigmatic epidemiology of nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) has a unique and complex etiology that is not completely understood. Although NPC is rare in most populations, it is a leading form of cancer in a few well-defined populations, including natives of southern China, Southeast Asia, the Arctic, and the Middle East/North Africa. The distinctive racial/ethnic and geographic distribution of NPC worldwide suggests that both environmental factors and genetic traits contribute to its development. This review aims to summarize the current knowledge regarding the epidemiology of NPC and to propose new avenues of research that could help illuminate the causes and ultimately the prevention of this remarkable disease. Well-established risk factors for NPC include elevated antibody titers against the Epstein-Barr virus, consumption of salt-preserved fish, a family history of NPC, and certain human leukocyte antigen class I genotypes. Consumption of other preserved foods, tobacco smoking, and a history of chronic respiratory tract conditions may be associated with elevated NPC risk, whereas consumption of fresh fruits and vegetables and other human leukocyte antigen genotypes may be associated with decreased risk. Evidence for a causal role of various inhalants, herbal medicines, and occupational exposures is inconsistent. Other than dietary modification, no concrete preventive measures for NPC exist. Given the unresolved gaps in understanding of NPC, there is a clear need for large-scale, population-based molecular epidemiologic studies to elucidate how environmental, viral, and genetic factors interact in both the development and the prevention of this disease.

Microsatellite Instability in Nasopharyngeal and Lymphoepithelial Carcinomas of the Head and Neck

Lymphoepithelial carcinoma (LEC) is a descriptive diagnosis for an undifferentiated carcinoma that has a typical morphologic appearance of large vesicular cells with prominent nucleoli and infiltrating lymphocytes. Tumors with this histopathologic appearance in the head and neck can be categorized as either those that occur in endemic areas, such as Southeast Asia and are associated with Epstein-Barr virus (EBV) infection, or those that occur in other countries and are less commonly associated with EBV. The molecular changes in endemic EBV-related LEC have been fairly well studied and include both alterations in tumor suppressor genes and 1 report of high levels of microsatellite instability. In nonendemic LECs arising in western countries, there is very little data related to molecular mutational profiles. In this study, we examined 19 cases of LEC from the United States for evidence of microsatellite instability at the DNA level and for alterations in the DNA mismatch repair (MMR) system at the immunohistochemical staining level. Only 3/19 cases showed high-level microsatellite instability and only 1 of these showed an alteration in the DNA MMR protein expression hMLH1. These data suggest that alterations in DNA MMR system are not a common mechanism of tumorigenesis in LEC of the head and neck in a nonendemic country.

Construction of evolutionary tree models for nasopharyngeal carcinoma using comparative genomic hybridization data

Nasopharyngeal carcinoma (NPC) is a malignancy associated with remarkable racial and geographic factors. The development and progression of NPC may involve the accumulation of multiple genetic alterations over a long time. For understanding the putative order of genetic alteration in NPC tumorigenesis, we used evolutionary tree models (branching and distance-based tree models) to analyze comparative genomic hybridization (CGH) data of previously published NPC cases (n = 103). Consistent loss of 3p for both tree models was an important early event in NPC progression. Chromosome 12 gain was another important early event, and may represent a subclass different from 3p- derived subclasses of NPC. The tree models also suggested that at least two subclasses of 3p- derived NPC, one marked by 1q+, 9p-, and 13q- and the other marked by 14q-, 16q-, 9q-, and 1p-.

BCL2 family of apoptosis-related genes: functions and clinical implications in cancer

One of the most effective ways to combat different types of cancer is through early diagnosis and administration of effective treatment, followed by efficient monitoring that will allow physicians to detect relapsing disease and treat it at the earliest possible time. Apoptosis, a normal physiological form of cell death, is critically involved in the regulation of cellular homeostasis. Dysregulation of programmed cell death mechanisms plays an important role in the pathogenesis and progression of cancer as well as in the responses of tumours to therapeutic interventions. Many members of the BCL2 (B-cell CLL/lymphoma 2; Bcl-2) family of apoptosis-related genes have been found to be differentially expressed in various malignancies, and some are useful prognostic cancer biomarkers. We have recently cloned a new member of this family, BCL2L12, which was found to be differentially expressed in many tumours. Most of the BCL2 family genes have been found to play a central regulatory role in apoptosis induction. Results have made it clear that a number of coordinating alterations in the BCL2 family of genes must occur to inhibit apoptosis and provoke carcinogenesis in a wide variety of cancers. However, more research is required to increase our understanding of the extent to which and the mechanisms by which they are involved in cancer development, providing the basis for earlier and more accurate cancer diagnosis, prognosis and therapeutic intervention that targets the apoptosis pathways. In the present review, we describe current knowledge of the function and molecular characteristics of a series of classic but also newly discovered genes of the BCL2 family as well as their implications in cancer development, prognosis and treatment.

Sequence Variants in Toll-Like Receptor 10 Are Associated with Nasopharyngeal Carcinoma Risk

Nasopharyngeal carcinoma (NPC) is a common malignancy in southern China and Southeast Asia. Genetic susceptibility is a major factor in determining the individual risk of NPC in these areas. To test the association between NPC and variants in Toll-like receptor 10 (TLR10), we conducted a hospital-based case-control study in a Cantonese-speaking population in Guangdong province. Seven single nucleotide polymorphisms in TLR10, selected with a tagging algorithm, were genotyped. When assessing each unique haplotype compared with the most common haplotype, "GAGTGAA," with the expectation-maximization algorithm in Haplo.stats, the risk of developing NPC was significantly elevated among men who carried the haplotype "GCGTGGC" (P = 0.005). After adjusting for age, gender, and VCA-IgA antibody titers, this association was more significant (P = 0.0007). To further assess the overall differences of haplotype frequency profiles between cases and healthy controls, the global score test, considering all haplotypes and adjusting for age, gender, and VCA-IgA antibody titers, gave a haplo score of 27.52 with P = 0.002. The haplotype specific odds ratio was 2.66 (confidence interval, 1.34-3.82) for GCGTGGC. We concluded that in this Cantonese population-based study, haplotype GCGTGGC with frequency of 11.4% in TLR10 was found to be associated with NPC and this association was statistically significant after adjusting for age, gender, and VCA-IgA antibody titers. It is possible that this is not a causal haplotype for NPC; rather, it is in strong linkage disequilibrium with a causal single nucleotide polymorphism in close proximity.

Purification of novel UBAP1 protein and its decreased expression on nasopharyngeal carcinoma tissue microarray

Recently, the UBAPl gene, a putative nasopharyngeal carcinoma (NPC) related gene, which is located at human chromosome 9p21-22 where loss of heterozygosity frequently occurs in NPC, was cloned. The present study aimed to explore the purification approach to UBAP1 protein and its expression pattern in NPC with tissue microarray. The full length coding sequence of UBAP1 was subcloned into a prokaryotic expression vector, pGEX-4T-2, and expressed in Escherichia coli as a GST-fusion protein. With modification of the purification method, GST-UBAP1 fusion protein achieved a high level of purity. The New Zealand rabbit was immunized with the purified fusion protein to prepare polyclonal antiserum following standard protocols. With this antiserum, high-throughput analysis of UBAP1 protein expression using immunohistochemistry was performed on self-made tissue microarrays consisting of 316 nasopharyngeal specimens from 148 NPC and 168 non-cancerous nasopharyngeal epithelia with different morphological features. Consequently, we found that there was a significant decrease in the percentage of positive expression in all NPC on protein levels for UBAP1 (23%), compared to that of the non-NPC (89%) (P<0.01). The result suggests that UBAP1 might be a potential effective diagnosis candidate for NPC and decreased expression of UBAP1 protein is a possible point of dysfunction along the pathogenesis pathway for NPC that may contribute to malignant transformation.

Global gene expression profile of nasopharyngeal carcinoma by laser capture microdissection and complementary DNA microarrays

A number of genetic and epigenetic changes underlying the development of nasopharyngeal carcinomas have recently been identified. However, there is still limited information on the nature of the genes and gene products whose aberrant expression and activity promote the malignant conversion of nasopharyngeal epithelium. Here, we have performed a genome-wide transcriptome analysis by probing cDNA microarrays with fluorescent-labeled amplified RNA derived from laser capture microdissected cells procured from normal nasopharyngeal epithelium and areas of metaplasia-dysplasia and carcinoma from EBV-associated nasopharyngeal carcinomas. This approach enabled the identification of genes differentially expressed in each cell population, as well as numerous genes whose expression can help explain the aggressive clinical nature of this tumor type. For example, genes indicating cell cycle aberrations (cyclin D2, cyclin B1, activator of S-phase kinase, and the cell cycle checkpoint kinase, CHK1) and invasive-metastatic potential (matrix metalloproteinase 11, v-Ral, and integrin beta(4)) were highly expressed in tumor cells. In contrast, genes underexpressed in tumors included genes involved in apoptosis (B-cell CLL/lymphoma 6, secretory leukocyte protease inhibitor, and calpastatin), cell structure (keratin 7 and carcinoembryonic antigen-related cell adhesion molecule 6), and putative tumor suppressor genes (H-Ras-like suppressor 3, retinoic acid receptor responder 1, and growth arrested specific 8) among others. Gene expression patterns also suggested alterations in the Wnt/beta-catenin and transforming growth factor beta pathways in nasopharyngeal carcinoma. Thus, expression profiles indicate that aberrant expression of growth, survival, and invasion-promoting genes may contribute to the molecular pathogenesis of nasopharyngeal carcinoma. Ultimately, this approach may facilitate the identification of clinical useful markers of disease progression and novel potential therapeutic targets for nasopharyngeal carcinoma.

NGX6 gene inhibits cell proliferation and plays a negative role in EGFR pathway in nasopharyngeal carcinoma cells

Nasopharyngeal carcinoma (NPC) is a common cancer in South China but is rare in other parts of the world. A novel NPC-related gene was isolated by location candidate cloning strategy, whose expression was down-regulated in NPC. This gene was designated human NGX6 (Genbank accession AF188239) and encoded a predicted protein of 338 amino acids that harbors an EGF-like domain. The effects of NGX6 on cells from human NPC cell line HNE1 were investigated. The cells transfected with NGX6 had a markedly high expression of NGX6, leading to significant decrease in cell proliferation and the capability to form colonies in soft agar, delaying the G0-G1 cell cycle progression. Flow cytometry assay indicated that the expression of cyclin D1 significantly decreased in NGX6-transfected HNE1 cells as well as cyclin A and E. There was a delay in tumor formation and a dramatic reduction in tumor size when cells transfected with NGX6 were injected into nude mice. In another way, we found NGX6 played a negative role in EGFR Ras/Mek/MAPK pathway. We propose that NGX6, as an EGF-like domain gene, could delay cell cycle G0-G1 progression and thus inhibit cell proliferation by negatively regulating EGFR pathway in NPC cells and down-regulating the expression of cyclin D1 and E.

Serum EBV DNA as a Biomarker in Primary Nasopharyngeal Carcinoma of Indian Origin

BACKGROUND

Nasopharyngeal carcinoma (NPC) is a unique tumor due to its etiology and endemic distribution. Ethnic and regional factors are found to strongly influence the risk of disease; however, there have been no well-conducted studies on Indian patients. The present study assesses the relationship between Epstein-Barr Virus (EBV) and sporadic Indian NPC and the role of serum EBV DNA in NPC detection.

METHODS

Primers directed against non-polymorphic Epstein-Barr nuclear antigen-1 (EBNA-1) gene were used to detect the presence of EBV DNA from fresh tissue and serum in NPC, using PCR.

RESULTS

EBV DNA was detected in 69% of the biopsies and 58% of the serum of the NPC patients. With respect to histology, WHO Type III NPC, WHO Type II tumors and WHO I tumors showed 100%, 72.2% and 33% EBV positivity, respectively. EBV positivity was also observed in 23% (6/26) of benign samples. All biopsies of patients with positive serum samples were positive for EBV DNA.

CONCLUSION

EBV infection was found in sporadic NPC of South Indian origin, which confirms the etiological role of EBV in NPC. Detection of EBNA-1 in the serum and corresponding tissues of NPC patients suggests that the serum EBV DNA originates from NPC and also indicates the benefit of circulating viral DNA as an early marker in the diagnosis of NPC. Serum DNA-PCR methods can be extrapolated to follow-up studies involving tumor regression or to assess the response to various therapies.

Quantification of circulating DNA in the plasma and serum of cancer patients

A variety of tumor-genetic alterations have been identified circulating free-form in the plasma and serum of cancer patients that may have diagnostic and prognostic implications. Currently, no consensus exists as to whether plasma or serum is preferable for circulating nucleic acid analysis, and the impact of collection and processing on yield is unknown. We prospectively assessed DNA content in paired plasma and serum obtained from 10 patients with AJCC stage IV advanced metastatic melanoma. Blood (30 mL) was collected from each patient as follows: 10 mL each was processed immediately for serum and plasma and an additional 10 mL was incubated overnight at 37 degrees C and processed for serum. In addition, blood was collected from 25 normal healthy donor volunteers to determine the concentration of free DNA circulating in paired plasma and serum. DNA was isolated from 800 microl of plasma or serum and quantified. Median-free DNA concentrations were fourfold greater in serum than in the corresponding plasma sample. Serum isolated from blood allowed to clot overnight yielded four times more DNA than serum processed immediately. Among normal healthy volunteers, only serum contained detectable free DNA. These findings provide conclusive evidence that elevated levels of circulating DNA could be identified consistently in patients with cancer than in normal healthy donors. Furthermore, the method of blood processing may significantly affect the levels of circulating nucleic acids and impact the investigator's results. Significant consideration must be given to the methods by which circulating nucleic acids are obtained for clinical analysis.

Chromosome 13q12 region critical for the viability and growth of nasopharyngeal carcinoma hybrids

Allelic losses of chromosome 13 are often detected in nasopharyngeal carcinoma (NPC) and other cancers, implicating the presence of possible tumor suppressor genes (TSGs) on this chromosome. To identify candidate regions from larger and multiple lost areas observed from direct tumor studies, the technique of monochromosome transfer was utilized to provide functional evidence to verify and define these deletion findings. An intact chromosome 13 was transferred into the NPC HONE1 cell line. Resultant hybrids were used to map putative TSG activity. A critical region at 13q12 was non-randomly eliminated in all surviving microcell hybrids around the marker D13S893; these hybrids were uniformly tumorigenic. Although a known TSG, BRCA2, is mapped close to this critical region, no aberrant expression of this gene was detected in microcell hybrids and other NPC cell lines. These results suggest that at least one novel growth control gene on chromosome 13q12, which is not the BRCA2 gene, is essential for hybrid selection and may play a critical role in tumorigenicity.

PUMA in head and neck cancer

Genetic alterations of p53, which monitors DNA damage and operates cellular checkpoints, is a major factor in the development of many types of cancer in human. PUMA, a direct mediator of p53-associated apoptosis, was recently identified. The PUMA gene was mapped to chromosomal arm 19q, a region frequently deleted in head/neck and lung cancers. We analyzed 30 primary tumors (15 head/neck and 15 lung) for loss of heterozygosity (LOH) at 19q using seven widely spaced microsatellite markers. LOH in at least one marker was present in 8 (56%) of the head/neck and 4 (26.6%) of the lung cancer samples. Overall, D19S408 and D19S412, showed the highest rates of allelic loss (23.3 and 16.6%, respectively). We then sequenced the entire coding region of the PUMA gene in all the 30 primary tumors and in 10 head/neck cancer cell lines. No mutations of PUMA were detected in any samples examined, regardless of the mutational status of the p53 gene. Forced expression of wild-type PUMA in JHU-012 and JHU-013 head/neck cancer cell lines significantly inhibited colony formation. Although PUMA suppresses tumor cell growth in head/neck cancer, it does not appear to be a direct target of inactivation in head and neck tumorigenesis.

Identification of tissue-specific genes in nasopharyngeal epithelial tissue and differentially expressed genes in nasopharyngeal carcinoma by suppression subtractive hybridization and cDNA microarray

Suppression subtractive hybridization (SSH) was performed for isolation of tissue-specific genes in nasopharyngeal epithelial tissue, by use of cDNAs from human adult nasopharyngeal epithelial tissue as tester and mixed cDNAs from esophagus, lung, liver, heart, stomach, spleen, skeletal muscle, kidney, and skin as drivers. Fourteen differentially expressed genes in nasopharyngeal epithelial tissue were obtained. Among these genes, LPLUNC1 and SPLUNC1 were confirmed to be specifically expressed in nasopharyngeal epithelial tissue and the trachea. A novel transcript of SPLUNC1, which we designate NASG, was found. We also combined SSH and cDNA microarray hybridization to identify genes whose expressions were altered in nasopharyngeal carcinoma (NPC). We used NPC cell line HNE1 and primary human embryo nasopharyngeal epithelial cells in one SSH experiment, and NPC biopsies and normal adult nasopharyngeal epithelial tissue in another. Some 1,200 SSH inserts from four subtractive cDNA libraries were arrayed onto nylon membranes by use of robotic printing. Differential gene expression was verified by hybridizing of the membranes with radioactively labeled first-strand cDNA from NPC cell line HNE1, primary human embryo nasopharyngeal epithelial cells, NPC biopsies, and normal adult nasopharyngeal epithelial tissue. Seventeen differentially expressed genes in NPC were obtained. Among these genes, we identified SPLUNC1 and LPLUNC1 to be down-expressed in NPC biopsies (34/48, 33/48).

Monochromosome transfer provides functional evidence for growth-suppressive genes on chromosome 14 in nasopharyngeal carcinoma

In many cancers, including nasopharyngeal carcinoma (NPC), extensive and multiple regions of allelic loss occur on chromosome 14. However, to date no functionally conclusive tumor suppressor genes have yet been identified on this chromosome. Through use of the monochromosome transfer technique, this study provides functional evidence for the importance of two discrete regions of chromosome 14. A newly established A9 mouse donor cell line containing an intact copy of chromosome 14 was used for transfer of this intact chromosome into the NPC HONE1 cell line. Twelve independently established microcell hybrids demonstrated uniform loss of specific chromosome 14 loci from both endogenous and exogenous alleles. By microsatellite typing and fluorescence in situ hybridization with BAC probes, the two critical regions were localized to 14q11.2-13.1 and 14q32.1. Selective elimination of these regions during hybrid selection was strongly associated with both hybrid survival and tumor growth in vivo. This functional evidence now narrows down the candidate areas for further studies and suggests that at least two hitherto unidentified growth-related genes localized on two critical regions of chromosome arm 14q play an important role in tumorigenesis.

Polymeric immunoglobulin receptor polymorphisms and risk of nasopharyngeal cancer

BACKGROUND

Epstein-Barr virus (EBV) associated nasopharyngeal cancer (NPC) is an important squamous cell cancer endemic in Southeast Asia and the Far East and can be considered a multifactorial genetic disease. This research explores potential associations between nasopharyngeal epithelial EBV receptor and NPC susceptibility. To prove the hypothesis, we evaluated two candidate genes, complement receptor 2 (CR2) and polymeric immunoglobulin receptor (PIGR) by using 4 SNPs, CR2IVS2-848C-->T, PIGRIVS3-156G-->T, PIGR1093G-->A and PIGR1739C-->T, to genotype 175 cases and 317 controls, divided into Thai, Chinese and Thai-Chinese based on their respective ethnic origins.

RESULTS

The results obtained indicated that PIGR is an NPC susceptibility gene. The risk association pertaining to each ethnic group was detected for homozygous PIGR1739C with a significant ethnic group adjusted OR (95%CI) of 2.71(1.72-4.23) and p < 0.00001. Haplotype of the two missense PIGR SNPs, 1093G-->A and 1739C-->T, and sequence analyses have confirmed the role of the nucleotide PIGR1739 and excluded possibility of an additional significant nonsynonymous NPC susceptibility SNP.

CONCLUSIONS

We present genetic evidence leading to hypothesize a possibility of PIGR to function as the EBV nasopharyngeal epithelium receptor via IgA-EBV complex transcytosis failure. The PIGR1739C-->T is a missense mutation changing alanine to valine near endoproteolytic cleavage site. This variant could alter the efficiency of PIGR to release IgA-EBV complex and consequently increase the susceptibility of populations in endemic areas to develop NPC.

Genetic and epigenetic changes in nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is a malignancy with remarkable racial and geographic distribution. The development of this EBV-associated cancer likely involves cumulative genetic and epigenetic changes in a background of predisposed genetic and environmental factors. Genome-wide studies have unravelled multiple chromosomal abnormalities with involvement of specific oncogenes and tumour suppressor genes. Alterations of genes such as Ras association domain family 1A (RASSF1A), p16/INK4A, p14/ARF suggest that multiple cellular pathways were dysregulated in the NPC cells. Studies on the precancerous lesions revealed early genetic changes and a critical role of EBV latent infection in the development of this cancer. Based on the existing findings, a pathogenetic model for NPC is proposed.

Mapping of nasopharyngeal carcinoma tumor-suppressive activity to a 1.8-megabase region of chromosome band 11q13

Nasopharyngeal carcinoma (NPC) is a malignancy that is particularly prevalent among populations from Southern China and Southeast Asian countries. Evidence for a genetic contribution to the disease has been documented, although the genetic basis for NPC development is not yet fully understood. Previous functional evidence of tumor-suppressive activity on chromosome band 11q13 in NPC was obtained using a microcell-mediated chromosome-transfer approach with HONE1 NPC cells. In the present study, this region was subjected to a detailed investigation of microcell hybrids and their tumor segregants using microsatellite analysis to narrow down the region of tumor-suppressive activity. Fluorescence in situ hybridization was also performed with BAC and cosmid probes to confirm the microsatellite data. The critical region responsible for tumor suppression was narrowed down to a 1.8-Mb interval, which does not tolerate an additional normal allele by chromosome transfer. One or two alleles from either endogenous or exogenous chromosomes at 11q13 were consistently eliminated during tumor growth. Results of this study suggest that a candidate tumor-suppressor gene, not the MEN1 gene, maps between D11S4907 and GSTP1 in NPC.

Distribution of HLA-B alleles in nasopharyngeal carcinoma patients and normal controls in Thailand

HLA-B frequencies in 54 unrelated nasopharyngeal carcinoma (NPC) patients and 49 healthy random controls in Thailand were investigated by direct DNA sequencing. Similar to previous reports in Chinese NPC patients, HLA-B*4601 was observed at a greater frequency in patients (21/54 (40%)) compared to controls (7/49 (14%). An increase in HLA-B*51012 was also demonstrated. B*51012 was present in 6/54 (11%) NPC patients but was not observed (0%) in controls. B*44032 was associated with a decreased risk. Five out of 54 (9%) NPC patients had B*44032 compared to 14/49 (29%) in the control group.

Serum and tissue c-erb B2, bcl-2, and mutant p53 oncoprotein levels in nasopharyngeal cancer

To date there are no prognostic factors that can account for the biology and disease behavior in nasopharyngeal cancer. Therefore, identification of new factors that can help in predicting the behavior of the disease and characterizing the subgroup with more aggressive tumors more likely to benefitfrom chemotherapy is important. In this study, c-erb B2, bcl-2, and mutant p53 protein levels were investigated in sera and tumor tissue of patients with nasopharyngeal cancer. Serum c-erb B2 levels were significantly higher in the patients than in the healthy subjects. No meaningful difference was observed between the serum and tissue levels of the mutant p53 protein. Tissue bcl-2 concentrations were considerably high. Our results suggest that serum c-erb B2 levels may aid in identifying a subgroup of patients with a poorer response rate to first-line treatment.

Distinct chromosomal aberrations in Epstein-Barr virus-carrying gastric carcinomas tested by comparative genomic hybridization

BACKGROUND & AIMS

Approximately 10% of gastric adenocarcinomas carry the human pathogenic Epstein-Barr virus (EBV). The role of EBV in the pathogenesis of these carcinomas remains to be established.

METHODS

To obtain a comprehensive overview of chromosomal aberrations in EBV-carrying and EBV-negative gastric carcinomas we performed comparative genomic hybridization (CGH) on 44 gastric carcinomas, 10 EBV-positive, and 34 EBV-negative. Additionally, DNA flow cytometry was done.

RESULTS

Loss of chromosome 4p (P < 0.001) and of 11p (P < 0.02) was exclusively restricted to EBV-carrying gastric carcinomas. In addition, loss of 18q (P < 0.02) was significantly more frequent in EBV-carrying gastric carcinomas. The latter involves loci, which have already been linked to gastric carcinogenesis such as the DCC and SMAD4 gene. In contrast, the losses on chromosome 4 and 11 do not yet harbor a gene related to gastric carcinogenesis. No significant correlation was found between DNA-ploidy and the EBV-status. A number of chromosomal aberrations were found at comparable frequencies in both groups, i.e., losses of chromosome 17, 12q, and loss of 1p. Interestingly, gains of 13q (10/34) and 3q (5/34) and loss of 1q (5/34) were solely observed in EBV-negative gastric carcinomas.

CONCLUSIONS

These data indicate that EBV-carrying and EBV-negative gastric carcinomas have different pathogenetic pathways in which EBV might play a crucial role.

Mutation and abnormal expression of the fragile histidine triad gene in nasopharyngeal carcinoma

OBJECTIVE

To determine alterations of fragile histidine triad (FHIT) gene in nasopharyngeal carcinoma and the correlation of FHIT gene with nasopharyngeal carcinogenesis.

STUDY DESIGN

Prospective study.

METHODS

A total of 28 nasopharyngeal carcinoma and 16 normal nasopharyngeal epithelium specimens were examined for abnormalities of FHIT gene by nested reverse-transcriptase-polymerase chain reaction and DNA sequencing.

RESULTS

The deletion of FHIT gene was not observed in 16 normal nasopharyngeal epithelium specimens. In 28 cases of nasopharyngeal carcinoma tissues, 12 (42.9%) exhibited FHIT aberrant transcripts. Complementary DNA sequencing revealed exonic deletion, small DNA insertion, synonymous mutation in exon 8, or frameshift mutation in exon 5.

CONCLUSIONS

The present results suggest that the FHIT gene may play an important role in the pathogenesis of nasopharyngeal carcinoma and may be one of the candidate tumor suppressor genes in nasopharyngeal carcinoma.

Comparative genomic hybridization detects multiple chromosomal amplifications and deletions in undifferentiated embryonal sarcoma of the liver

Undifferentiated embryonal sarcoma (UES) is the third most common hepatic malignancy in children. Previous reports have described a broad range of complex cytogenetic abnormalities in individual cases of hepatic UES. Herein we report the cytogenetic findings of six cases of hepatic UES at our institution analyzed by conventional cytogenetic methods and comparative genomic hybridization (CGH). The CGH demonstrated several chromosomal gains and deletions in each case, but there was no specific abnormality seen in every case. Patterns of chromosomal changes included gains of chromosome 1q (four cases), 5p (four cases), 6q (four cases), 8p (three cases), and 12q (three cases), and losses of chromosome 9p (two cases), 11p (two cases), and chromosome 14 (three cases). The three cases in which CGH showed gains in the 12q region were studied specifically for amplifications of MDM2 and CDK4, two genes that have been shown to be amplified in other soft tissue sarcomas. However, Southern analysis showed no amplification of MDM2 or CDK4 in these three cases. Further analysis will be needed to determine the critical events in the pathogenesis of these malignant pediatric liver tumors.