Linkage of a nasopharyngeal carcinoma susceptibility locus to the HLA region

Familial nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) has a striking geographical and ethnical distribution. It occurs with high frequency in southern China and Southeast Asia. Family clustering was also observed in NPC and a typical family with 15 NPC cases was introduced in this paper. Epidemiological and genetic studies have been carried out in the previous decades and vast information was accumulated for familiar NPC, in terms of risk factors, inheritance mode, and involvement of gene polymorphisms. The major findings in this field were summarized. Furthermore, future directions leading to understanding the genetic mechanism of the familial form of NPC was also discussed.

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.

Risk of invasive cervical cancer associated with polymorphic HLA DR/DQ haplotypes

The genes encoding human leukocyte antigens (HLA) have shown to be associated with cervical neoplasia. To obtain reliable data on HLA associations with cervical tumors, the study should be performed within a strictly defined cohort. To investigate the population attributable risk of cervical cancer associated with the HLA class II haplotypes DR15 and DQ6 (DQA1*0102 and DQB1*0602), we performed a nested case-control study of 85 women who developed invasive cervical cancer and 120 healthy women from a population-based cohort of Swedish women. The relative risks of cervical cancer among DR15 and DQ6-positive women were 3.73 [confidence interval (CI): 1.8-7.4] and 4.33 (CI: 2.1-8.5), corresponding to population attributable proportions of 27.9% and 30.8%, respectively. A susceptibility locus in the HLA class II region is involved in a substantial fraction of the etiology of cervical cancer.

Genome-wide scan for familial nasopharyngeal carcinoma reveals evidence of linkage to chromosome 4

Nasopharyngeal carcinoma (NPC) occurs with high frequency in Asian populations, especially among people of Cantonese ancestry. In areas with high incidence, NPC clusters in families, which suggests that both geography and genetics may influence disease risk. Although the HLA-Bw46 locus is associated with increased risk of NPC, no predisposing genes have been identified so far. Here we report the results of a genome-wide search carried out in families at high risk of NPC from Guangdong Province, China. Parametric analyses provide evidence of linkage to the D4S405 marker on chromosome 4 with a logarithm of odds for linkage (lod) score of 3.06 and a heterogeneity-adjusted lod (hlod) score of 3.21. Fine mapping with additional markers flanking D4S405 resulted in a lod score of 3.54 and hlod score of 3.67 for the region 4p15.1-q12. Multipoint nonparametric linkage analysis gives lod scores of 3.54 at D4S405 (P = 5.4 x 10(-5)) and 4.2 at D4S3002 (P = 1.1 x 10(-5)), which is positioned 4.5 cM away from D4S405. When Epstein Barr virus antibody titer was included as a covariate, the lod scores reached 4.70 (P = 2.0 x 10(-5)) and 5.36 (P = 4.36 x 10(-6)) for D4S405 and D4S3002, respectively. Our findings provide evidence of a major susceptibility locus for NPC on chromosome 4 in a subset of families.

Definition of three minimal deleted regions by comprehensive allelotyping and mutational screening of FHIT,p16(INK4A), and p19(ARF) genes in nasopharyngeal carcinoma

BACKGROUND

Recurrent deletion on a chromosomal location in tumor cells can be detected by frequent allelic loss and generally is considered to be an indication of the existence of a tumor suppressor gene (TSG) in the region. In the current study, using fluorescent-labeled, high-density microsatellite markers for allelotyping, the authors pinpointed three minimal deleted regions (MDRs) and screened mutations of putative TSGs on chromosomes 3, 9, and 11 in nasopharyngeal carcinoma (NPC) cases occurring in Taiwan.

METHODS

A total of 133 informative microsatellite markers were used on chromosomes 3, 9, and 11 with an average marker density of 4 centimorgans (cM) for the allelotyping of genomic DNAs isolated from NPC tissues and their corresponding lymphocytes in 48 patients. The correlation between allelic loss and the clinicopathologic parameters of NPC tissues was examined. In addition, putative TSGs including FHIT, p16(INK4a), and p19(ARF) were selected for mutation screening to investigate their potential participation in NPC tumorigenesis.

RESULTS

Of 3787 informative allelotyping data, 25 frequent allelic losses (or loss of heterozygosity [LOH]) in 13 cytogenetic loci were identified based on a deletion frequency that was greater than the average of allelic loss on that particular chromosome. Several significant associations were determined after statistical analysis of the correlation between allelic loss and clinicopathologic parameters. The allelic losses by D9S318 and D11S1304 were associated with N2/N3 (P = 0.035 and P = 0.005, respectively), and those by D9S905 and D11S1304 were associated with grouped American Joint Committee on Cancer (AJCC) Stage III/IV samples (P = 0.022 and P = 0.017, respectively) of NPC tissues. In addition, three MDRs were revealed on 3p25.3-24.1 (< 19 cM), 3p23-21.31 (< 9 cM), and 11q22.1-23.2 (< 8 cM). To examine somatic mutations in previously reported TSGs located near these frequent LOH loci, three candidate genes, p16(INK4a), p19(ARF), and FHIT, were analyzed. Point mutations in the coding region of FHIT and in the intron 1 splicing acceptor site of both p16(INK4a) and p19(ARF) were detected in NPC cell lines. Sequence analysis of both p16(INK4a) and p19(ARF) transcripts revealed that the point mutation resulted in skipping of exon 2 and the generation of shorter transcripts.

CONCLUSIONS

High-density allelotyping permitted the discovery of 3 MDRs on 3p25.3-24.1 (< 19 cM), 3p23-21.31 (< 9 cM), and 11q22.1-23.2 (< 8 cM) and a correlation was determined between allelic loss and clinicopathologic parameters of NPC tissues. More important, one somatic mutation in NPC cell lines on the intron 1/exon 2 splicing acceptor site of the INK4a/ARF locus was found to result in exon 2 skipping both p16(INK4a) and p19(ARF) transcripts, which presumably inactivates the functions of both the p16(INK4a) and p19(ARF) proteins.

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.

Microsatellite analyses of loci at 7q31.3-q36 reveal a minimum of two common regions of deletion in nasopharyngeal carcinoma

OBJECTIVE

Our goal was to better define the extent and specificity of deletion in the 7q32-qter chromosomal region in nasopharyngeal carcinoma (NPC).

DESIGN AND SETTING

Polymerase chain reaction-based deletion analysis was performed on DNA samples from 24 paired NPCs and corresponding germlines using 13 microsatellite markers mapped to chromosome subbands 7q31.3-q36.

RESULTS

Loss of heterozygosity of at least 1 marker in this interval was found in 18 (75%) of 24 tumor specimens. Particularly frequent allelic losses were identified at 5 loci: D7S495 (46%), D7S509 (42%), D7S500 (45%), D7S631 (30%), and D7S514 (35%). Two shortest regions of overlap could be identified in this interval, although the most common shortest region of overlap appeared to lie around D7S500 between but not including D7S631 and D7S495, on chromosome subband 7q32.

CONCLUSION

These results suggest that at least 2 putative tumor suppressor genes important in the pathogenesis of NPC are present in the examined interval, an interval that has also been found to harbor deletions in breast and prostate carcinomas.

Genetics and the common cancers

Rare highly penetrant genes cannot account for much of the familial risk for most common cancers, and there is increasing evidence that a high proportion of cancers arise in a susceptible minority who carry low-penetrance genes or gene combinations. The evidence for the existence of such genes and the prospects for identifying them are reviewed.

Association between HLA-A/-B antigens and -DRB1 alleles and nasopharyngeal carcinoma in Tunisia

Using serologic and molecular methods, 45 nasopharyngeal carcinoma (NPC) patients were typed for HLA class I and class II and were compared to 100 unrelated normal Tunisians. Our results showed that the antigen frequency of HLA-B13 and allelic frequencies of DRB1*03, DRB1*15 were significantly higher in the NPC patients than in the control group (15.5 vs. 4; 26.4 vs. 11.5, and 14.4 vs. 6.5%, respectively) probably indicating a positive association with NPC. Moreover, we observed that HLA-A23 was absent in our NPC sample and was present in 18% of normal controls, and HLA-DRB1*11 was less frequent among the patients compared to the controls (5.5 vs. 14%) suggesting a protective effect of this association with NPC.

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.

Biology and disease associations of Epstein-Barr virus

Epstein-Barr virus (EBV) is a human herpesvirus which infects almost all of the world's population subclinically during childhood and thereafter remains in the body for life. The virus colonizes antibody-producing (B) cells, which, as relatively long-lived resting cells, are an ideal site for long-term residence. Here EBV evades recognition and destruction by cytotoxic T cells. EBV is passed to naive hosts in saliva, but how the virus gains access to this route of transmission is not entirely clear. EBV carries a set of latent genes that, when expressed in resting B cells, induce cell proliferation and thereby increase the chances of successful virus colonization of the B-cell system during primary infection and the establishment of persistence. However, if this cell proliferation is not controlled, or if it is accompanied by additional genetic events within the infected cell, it can lead to malignancy. Thus EBV acts as a step in the evolution of an ever-increasing list of malignancies which are broadly of lymphoid or epithelial cell origin. In some of these, such as B-lymphoproliferative disease in the immunocompromised host, the role of the virus is central and well defined; in others, such as Burkitt's lymphoma, essential cofactors have been identified which act in concert with EBV in the evolution of the malignant clone. However, in several diseases in which the presence of EBV has more recently been discovered, the role of the virus is unclear. This review describes recent views on the EBV life cycle and its interlinks with normal B-cell biology, and discusses how this interrelationship may be upset and result in EBV-associated disease.

HLA class II alleles in Chinese patients with hepatocellular carcinoma

BACKGROUND/AIMS

Recent reports of an association between human leucocyte antigens (HLA) and persistence of hepatitis B virus infection, and the familial clustering of hepatocellular carcinoma raise the question of genetic susceptibility. Previous studies have been limited to serological phenotyping of HLA B and DR antigens. The aim of this study was to use molecular genotyping to investigate HLA class II as a risk factor for the development of hepatocellular carcinoma in Hong Kong Chinese.

METHODS

We determined HLA DRB1, DQA1, DQB1 and DPB1 alleles in 123 hepatitis B surface antigen positive patients (84 with hepatocellular carcinoma and 39 without) and 124 matched controls.

RESULTS

The alleles DRB1*1501 (36% of HCC patients versus 19% of controls, odds ratio=2.44), DQA1*0102 (42% versus 26%, odds ratio=2.07), and DPB1*0501 (80% versus 63%, odds ratio=2.35) were significantly more common in patients with hepatocellular carcinoma, and DQA1*03 (36% versus 56%, odds ratio=0.53), DQB1*0302 (4.% versus 13%, odds ratio=0.25) and DPB1*0201 (14% versus 29%, odds ratio=0.4) were found at significantly lower frequencies.

CONCLUSIONS

Although none of these associations was significant after correction for multiple testing, this report suggests that further investigations are warranted.

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.

Human leukocyte antigens related to Epstein-Barr virus-associated gastric carcinoma in Japanese patients

To assess the association between specific types of human leukocyte antigen and the risk of Epstein-Barr virus (EBV)-associated gastric carcinoma, serological typing for major histocompatibility complex class I and class II antigens was performed for 110 EBV-positive and 155 EBV-negative gastric carcinoma cases. In class I analysis, the frequency of B59 in the EBV-positive cases was higher than for the EBV-negative cases (odds ratio (OR) 3.06; 95% confidence interval (CI) 1.02-9.23). For class II antigens, DQ3 and DR9 frequencies in the EBV-positive cases were higher (OR 1.94; 95% CI 1.16-3.24 and OR 1.93; 95% CI 1.11-3.37, respectively), whereas DR11 frequency was lower than found in the EBV-negative cases (OR 0.10; 95% CI 0.01-0.79). After adjusting for multiple comparisons, only DR11 frequency remained significantly lower in the EBV-positive cases (P = 0.04), and the association of DQ3 was marginally significant (P = 0.05). These results suggest that the presence of DR11-restricted cytotoxic T cells (CTLs) related to EBV-associated gastric carcinoma, or a deficiency of DR11 and a high frequency of DQ3 may be genetic markers for a population at greater risk of EBV-associated gastric carcinoma. However, further extensive studies to more cases and DNA typing are needed because our findings in this study are exploratory.

The incidence of small abdominal aortic aneurysms and the change in normal infrarenal aortic diameter: implications for screening

AIM

to study the incidence of small abdominal aortic aneurysms (AAA), and to investigate what proportion of normal infrarenal aortic diameters (IAD) expand with age.

METHODS

longitudinal follow-up in a population-based aneurysm screening programme. The infrarenal aortic diameter (IAD) was measured by ultrasound. A second scan was performed in subjects with a normal aorta after an average of 5.5 years.

RESULTS

data were analysed from 4072 subjects, 464 with a small AAA and 3608 with a normal aorta. The infrarenal aorta expanded in 15% of subjects, but significant growth (>5 mm) occurred in only 7%. Age and initial diameter were independent predictors for aortic dilatation. The effect of diameter at first screen was non-linear. The relative risk for expansion increased dramatically for IADs over 2.5 cm (test for departure of trend: chi2=52, p<0.0001). The effect of age was also non-linear, the risk of expansion was highest in the 60-69 year old age group; test for departure of trend (chi2=13, p=0.002). The incidence of new aneurysms was 3.5 per 1000 person-years (py) (95% CI: 2.8-4.4). The highest incidence of new aneurysms was found in the 60 to 69 year old age group.

CONCLUSION

only a small proportion of the population is prone to aortic dilatation. Patients over 70 with an IAD <2.5 cm can be discharged from follow-up.

Genetic susceptibility to breast cancer: HLA DQB*03032 and HLA DRB1*11 may represent protective alleles

Tumors are believed to emerge only when immune surveillance fails. We wished to ascertain whether the failure to inherit putative protective alleles of HLA class II genes is linked to the development of breast cancer. We molecularly typed HLA DPB1, DQB1, DRB1, and DRB3 alleles in 176 Caucasian women diagnosed with early-onset breast cancer and in 215 ethnically matched controls. HLA DQB*03032 was identified in 7% of controls but in no patients with early-onset breast cancer (P = 0.0001). HLA DRB1*11 alleles were also significantly overrepresented (P < 0.0001) in controls (16. 3%) as compared with patients with early-onset breast cancer (3.5%). HLA DQB*03032 and HLA DRB1*11 alleles may have a protective role in human breast cancer.

Second malignant tumors in patients with nasopharyngeal carcinoma and their association with Epstein-Barr virus

Since previous published studies about second malignant tumors (SMTs) in nasopharyngeal carcinoma (NPC) patients usually included a limited sample size and did not attain consistent results, we conducted a large retrospective study in a cohort of 1,549 patients to assess the risk of SMT in NPC patients following radiotherapy (RT) in Taiwan. The follow-up period ranged from 2 to 16 years, with a median of 7 years. Thirty-nine patients developed SMTs during the 7,145 person-year follow-up [standardized incidence ratio (SIR): 2. 8; 95% confidence interval (CI): 2.0 to 3.9]. Increased risks of developing SMTs were observed for head and neck (H/N) cancer (SIR: 16.5; 95% CI: 10.0 to 26.8), gastric cancer (SIR: 5.5; 95% CI: 2.2 to 11.4) and leukemia (SIR: 9; 95% CI: 1.9 to 26.3). Paraffin-embedded specimens of secondary H/N cancer (11), secondary gastric cancer (6) and their corresponding NPC specimens were examined by EBER in situ hybridization to assess the association between Epstein-Barr virus (EBV) and these SMTs. Twenty-six primary H/N and 5 gastric cancer specimens were chosen as the control groups. In H/N cancer, EBV was detected in 3.8% of the primary cancers and 9.1% of the secondary cancers. All the positive specimens resulted from hypopharyngeal cancer. Of the secondary gastric cancers, only 1 case (16.6%) was associated with EBV. None of the primary gastric cancers was associated with EBV. Our results indicate an increased risk of developing SMTs, with a preference for head and neck cancer, gastric cancer and leukemia, in NPC patients after RT in Taiwan. Only a small proportion of the secondary H/N and gastric cancers was associated with EBV.

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.

A functional investigation of tumor suppressor gene activities in a nasopharyngeal carcinoma cell line HONE1 using a monochromosome transfer approach

Monochromosome transfers of selected chromosomes into a nasopharyngeal carcinoma (NPC) cell line were performed to determine if tumor suppressing activity for NPC mapped to chromosomes 9, 11, and 17. Current information from cytogenetic and molecular allelotyping studies indicate that these chromosomes may harbor potential tumor suppressor genes vital to NPC. The present results show the importance of CDKN2A on chromosome 9 in NPC development. There was no functional suppression of tumor development in nude mice with microcell hybrids harboring the newly transferred chromosome 9 containing an interstitial deletion at 9p21, whereas transfection of CDKN2A into the NPC HONE1 cells resulted in obvious growth suppression. Whereas intact chromosome 17 transfers into HONE1 cells showed no functional suppression of tumor formation, chromosome 11 was able to do so. Molecular analysis of chromosome 11 tumor segregants indicated that at least two tumor suppressive regions mapping to 11q13 and 11q22-23 may be critical for the development of NPC.

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 (EBV) and human disease: facts, opinions and problems

The human herpesvirus, Epstein-Barr virus (EBV), has classically been associated with two pathologies with frequencies approaching 100%. One of these, Burkitt's lymphoma (BL), is of B-cell origin and the other, nasopharyngeal carcinoma (NPC), is a tumour of poorly differentiated epithelial cells. More recently, EBV had been identified with frequencies from a few percent to 100% (in one case) with a variety of other malignancies. These include Hodgkin's disease (HD; where in the west, the frequency of association is about 50%), sino-nasal T-cell lymphomas, lymphoepitheliomas, some sarcomas and breast cancers, other cancers from the head and neck, and lymphomas arising in patients with immune dysfunctions. Since EBV is ubiquitous, with the vast majority of the world's population having met and seroconverted to the virus, the diversity of tumours with which it has now been associated represents a substantial health burden. In a recent IARC monograph, EBV was classified as a group 1 carcinogen. Here, the data on BL and NPC, as they relate to geographical restrictions, viral strain variation, co-factors in disease, and genetic components are reexamined. We raise the question whether in their origins, these tumours genuinely reflect distinct and independent events, as deemed at present, or may represent a response by different cell types to common extracellular factors. For example, a situation in Kenya apparently existed in the past, where both BL and NPC were observed in ethnic Africans with roughly equal frequencies; more recently, in Kenya, EBV has been identified in nearly 100% of the tumours in children with HD. We also consider tumours where the viral association is reportedly of low frequency, and offer explanations for these data, including the possibility of loss of the viral genome once malignancy has been initiated. If this phenomenon occurs as a frequent secondary event, EBV could be an even greater health risk than presently believed.

Frequent c-myc and Int-2 overrepresentations in nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is a commonly occurring tumor in southern China. Although several causative factors have now been recognized, the genetic basis underlying its tumorigenesis is still unclear. To identify potential chromosomal aberrations for further investigations, comparative genomic hybridization (CGH) analysis was applied to the study of genomic imbalances in 10 NPC biopsy specimens. Before CGH analysis, the tumor cell content within the biopsy specimens was enriched by tissue microdissection, and universal genome amplification was performed on the recovered DNA. Recurrent chromosomal gains were detected on 1q (6 of 10 cases), 2q (5 of 10 cases), 3q (7 of 10 cases), 6p (8 of 10 cases), 6q (5 of 10 cases), 7q11.2 (4 of 10 cases), 8q (6 of 10 cases), 11q13, 12, and 15q (8 of 10 cases each), 17q (6 of 10 cases), and 20q (5 of 10 cases). Common losses were identified on 3p (5 of 10 cases), 9p (5 of 10 cases), 11q14-qter (8 of 10 cases), and 14q (5 of 10 cases). Among these aberrations, 7, 8, and 11 gains were further investigated on a series of NPC tissue samples, by interphase fluorescent in situ hybridization (FISH), for the incidence of alpha-satellites: 7, 8, and 11 c-myc and Int-2. Low-level increases of alpha-satellite 7 (9 of 34 cases; 26.5%), alpha-satellite 8 (15 of 34 cases; 44%), and alpha-satellite 11 (8 of 32 cases; 25%) were detected, whereas high-level copy gains of c-myc (21 of 34 cases; 62%) and Int-2 (26 of 34 cases; 76.5%) were more frequently found. Our series is the first to identify genomic overrepresentations of c-myc and Int-2 in NPC. The high incidence of Int-2 amplifications strongly suggests a role of this proto-oncogene in the pathogenesis of NPC.

DNA typing of HLA class II genes (HLA-DR, -DQ and -DP) in Japanese patients with histiocytic necrotizing lymphadenitis (Kikuchi's disease)

The pathogenesis of histiocytic necrotizing lymphadenitis (HNL), which was reported first by Kikuchi et al. and Fujimoto et al. in 1972, is as yet unknown. HNL is frequently reported in Asian countries including Japan, however it is rare in Europe and North America. To elucidate whether the human leukocyte antigen (HLA) alleles and haplotypes are associated with HNL, we performed DNA typing of HLA class II genes (HLA-DR, -DQ, and -DP) in 86 patients with HNL and 525 unrelated healthy Japanese controls with polymerase chain reaction using sequence-specific oligonucleotide probes (PCR-SSOP). In this study, we found DPA1*01 and DPB1*0202 allele frequencies in HLA class II genes are significantly higher in HNL patients than in normal controls. It is known that the frequency of DPB1*0202 alleles is extremely low or absent in Caucasians (e.g., French 0.4%, Italian 0.8%) and Negroid (e.g., South African 0%, Hottentot 0%), but relatively frequent in Asians (e.g., Korean 9.9%, Japanese 4.5%). Previous reports have said the incidence of HNL is frequent in Asians but rare in other races. In light of this background, HLA class II genes of HNL and the incidence of HNL in Asian countries, including Japan, might have a positive relationship to DPA1*01 and DPB1*0202 allele.

Genetic susceptibility to HPV infection and cervical cancer

Squamous cell carcinoma of the cervix (SCCC) is one of the leading causes of death in developing countries. Infection with high-risk human papillomavirus (HPV) is the major risk factor to develop malignant lesions in the cervix. Polymorphisms of the MHC and p53 genes seem to influence the outcome of HPV infection and progression to SCCC, although controversial data have been reported. MHC are highly polymorphic genes that encode molecules involved in antigen presentation, playing a key role in immune regulation, while p53 is a tumor suppressor gene that regulates cell proliferation. The HPV E6 protein from high-risk types binds p53 and mediates its degradation by the ubiquitin pathway. The role of these polymorphisms in genetic susceptibility to HPV infection and to SCCC remains under investigation.

The complete genomic sequence of 424,015 bp at the centromeric end of the HLA class I region: gene content and polymorphism

We report here the genomic sequence of the centromeric portion of HLA class I, extending 424,015 bp from tumor necrosis factor alpha to a newly identified gene approximately 20 kb telomeric of Otf-3. As a source of DNA, we used cosmids centromeric of HLA-B that had been mapped previously with conventional restriction digestion and fingerprinting and previously characterized yeast artificial chromosomes subcloned into cosmids and mapped with multiple complete digest methodologies. The data presented provide a description of the gene content of centromeric HLA class I including new data on intron, promoter and flanking sequences of previously described genes, and a description of putative new genes that remain to be characterized beyond the structural information uncovered. A complete accounting of the repeat structure including abundant di-, tri-, and tetranucleotide microsatellite loci yielded access to precisely localized mapping tools for the major histocompatibility complex. Comparative analysis of a highly polymorphic region between HLA-B and -C was carried out by sequencing over 40 kb of overlapping sequence from two haplotypes. The levels of variation observed were much higher than those seen in other regions of the genome and indeed were higher than those observed between allelic HLA class I loci.

Nasopharyngeal carcinoma in Malaysian Chinese: salted fish and other dietary exposures

We interviewed 282 histologically confirmed cases of nasopharyngeal carcinoma (NPC) in Chinese residents of Selangor and the Federal Territory, Malaysia, and an equal number of Chinese age-, sex-, and length-of-residence-matched controls sampled from the general population. Consumption of 55 dietary items during childhood, and 5 years pre-diagnosis of NPC, was analyzed by univariate and multivariate methods. Four salted preserved foods (fish, leafy vegetables, egg and root), fresh pork/beef organ meats and beer and liquor consumption exhibited strong positive associations, and 4 vegetable/fruit combinations strong negative associations with NPC. Factor analysis and multivariable modeling using estimated factor scores strongly supported separate effects on NPC of vegetables/fruits, salted preserved foods, pork/beef organ meats and beer/liquor consumption. Multivariable modeling associated NPC most clearly with high consumption of salted fish, salted eggs, pork/beef liver and beer and low consumption of Chinese flowering cabbage, oranges/tangerines and shrimp. A strong residual association of social class with NPC remained after adjustment for diet, which is consistent with a substantial role for non-dietary environmental factors.

Functional evidence for a nasopharyngeal carcinoma tumor suppressor gene that maps at chromosome 3p21.3

Nasopharyngeal carcinoma is a malignancy that is prevalent among populations from Southeast Asia. Epidemiological studies indicate that genetic predisposition, Epstein-Barr virus, and environmental conditions may play a role in determining incidence. Molecular studies have implicated a tumor suppressor gene(s) on the short arm of chromosome 3. In this study we provide functional evidence, via monochromosome transfer, for a tumor suppressor gene(s) activity in chromosome 3p21.3.

DNA typing of HLA class I (HLA-A) and class II genes (HLA-DR, -DQ and -DP) in Japanese patients with gastric cancer

Gastric cancer is multifactorial disease and several reports have described genetic factors involved in pathogenesis of gastric cancer. Recently, it was reported that HLA class II gene DQB1*0301 was strongly associated with gastric cancer in Caucasian population (20). We performed DNA typing of HLA class I (HLA-A) and HLA class II genes (HLA-DR, DQ and DP) to elucidate the HLA alleles or HLA haplotypes associated with gastric cancer in Japanese population using polymerase chain reaction-sequence-specific oligonucleotide probe analysis in 88 unrelated patients with gastric cancer and 525 unrelated healthy controls. We observed slight difference in frequencies of some HLA alleles and haplotypes between gastric cancer patients and controls; however, after Bonferroni correction, statistical significance was not confirmed. It is possible that environmental factors such as diet cover the contribution of genetic factors to the disease in Japanese population, which has a higher frequency of gastric cancer than do Caucasian populations, most likely due to more exposure to environmental risk factors.

A case-control study of risk factors of nasopharyngeal carcinoma

Risk factors and nasopharyngeal carcinoma (NPC) in residents of Guangzhou city were investigated in a case-control study: 104 cases were compared with an equal number of age, sex, and neighborhood-matched controls. The results of multiple conditional regression of logistic model showed that plum vegetable (adjusted OR = 1.81, 95% CI 1.01-3.33), preserved prune (adjusted OR = 2.95, 95% CI 1.04-8.41), no separate kitchen (if >35 years, adjusted OR = 1.98, 95% CI 1.24-3.75), kitchen range without chimney (if >10 years, adjusted OR = 2.72, 95% CI 1.56-4.73) and hereditary factor (adjusted OR = 8.27, 95% CI 1.94-35.54) were significantly associated with an increased risk of NPC. Grape (adjusted OR = 0.31, 95% CI 0.17-0.58) may be a protective factor.

Association between microsatellites within the human MHC and nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) has been known to be associated with specific HLA haplotypes, in particular HLA A2, B46 and A33, B58 haplotypes. A linkage study based on this observation suggested that HLA antigens are not the cause of NPC but that there exists a gene that lies close to if not within the major histocompatibility complex locus and confers a greatly increased relative risk of NPC. Since then, no further work has elucidated the presence of this gene. One of the difficulties faced by researchers has been the size of the region of chromosome implicated. The MHC locus alone is almost 4 Mb in length, and the number of genes encoded within it is numerous. The purpose of our study was thus to reduce the region of DNA in which the NPC susceptibility gene is likely to be. We report that the NPC susceptibility gene may be within the centromeric end of the class-1 and the telomeric end of the class-III regions of the MHC, near the D6S1624 microsatellite locus, where the presence of allele 4 of the microsatellite conferred a 3 1/2-fold increase in the risk of NPC, the highest reported for a single locus, and the presence of allele 1 of the same microsatellite conferred a highly significant protective effect against NPC.

Epstein-Barr virus in gastric carcinoma in Suzhou, China and Osaka, Japan: association with clinico-pathologic factors and HLA-subtype

Information on geographic differences of Epstein-Barr virus (EBV) positivity and association with HLA in gastric carcinoma are limited. Therefore, the association of gastric carcinoma with EBV was examined in 118 patients from Suzhou, China, where the incidence of nasopharyngeal carcinoma (NPC) is high, and in 216 patients from Osaka, Japan, where the incidence of NPC is low, NPC being one of the EBV-associated carcinomas. Expression of HLA-A2 was also examined in some of these cases. The EBV genome was evidenced by PCR and in the tumor cells by in situ hybridization in 7/90 and 9/151 of cases from Suzhou and Osaka, respectively. Immunohistochemistry revealed that cancer cells in all cases with EBV did not express latent membrane protein-I. Type A was found in all cases positive for EBV. Among several histologic and clinical factors, only age of patients showed a correlation with EBV positivity: patients over 60 showed a higher frequency than patients below 60 years of age (p < 0.05). Typing of the HLA-A locus was possible in 16 cases positive for the EBV genome: 3 of 4 cases from Suzhou and 4 of 7 from Osaka were positive for HLA-A2 products. Severe lymphoid cell infiltration was found in 2 of 7 cases and 1 of 4 cases with and without the HLA-A2 type, respectively. The reported frequency of EBV positivity in Chinese living in Taiwan and in Japanese living in Hawaii is higher than in Suzhou, China, and Osaka, Japan, respectively. Our findings suggest that EBV association with gastric carcinoma is influenced by environmental and cultural factors.

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.

Familial Burkitt's lymphoma in Papua New Guinea

A study of Burkitt's lymphoma (BL) in Papua New Guinea for the years 1958-87 revealed four instances of familial BL. Incident cases occurred within 1 year of each other in the four families. Personal follow-up was possible for three of these families whose pedigrees showed that two or more siblings were affected. There was no significant variation of the incidence of BL by year of diagnosis or month of onset. There was significant variation in annual average incidence of BL between the three provinces studied, with the highest incidence in the Nuku and Lumi census districts (of the West Sepik Province). This is the first report of familial BL outside Africa.

Relations between nasopharyngeal carcinoma and magnesium and other alkaline earth elements in soils in China

Comparison of maps shows a striking geographical relation between high mortality rates from nasopharyngeal cancer in China and low contents of magnesium, calcium and strontium in the soil. We suggest that deficiencies of these elements in the soil could be indirect markers of aetiological factors, e.g. inhalable carcinogens of local natural origin. A search for such factors could be fruitful in further studies of environmental factors in the aetiology of nasopharyngeal carcinoma.

Different HLA-DR-DQ haplotypes are associated with cervical intraepithelial neoplasia among human papillomavirus type-16 seropositive and seronegative Swedish women

To analyze whether HLA may be a determinant of the risk of developing cervical cancer precursor lesions, the association between HLA and cervical neoplasia among HPV16-seropositive and -negative subjects was determined in a population-based cohort in the Västerbotten county of Northern Sweden. HLA genotyping of DR and DQ was done by PCR in 74 patients and 164 healthy controls matched for age, sex and area of residence. The presence of DQA1*0102 was weakly associated with cervical neoplasia in HPV16-seropositive patients. DQB1*0602 was weakly associated with disease in all patients, but was strongly increased among HPV16-seropositive patients compared to HPV16-seropositive controls. DR15 had an association with disease that was particularly strong among HPV16-seropositive subjects. The haplotype DQA1*0102-DQB1*0602 (DQ6) was also weakly associated with disease in all patients and significantly increased among HPV16-positive patients when compared to HPV16-positive controls. A similar association was seen when analysis was restricted to CIN 2-3 patients. DQA1*0501-DQB1*0301 (DQ7) was more common among HPV16-negative patients than among HPV16-negative controls and was also more common among HPV16-negative patients than among HPV16-positive patients. In conclusion, DQA1*0102-DQB1*0602 (DQ6) is associated with an increased risk of cervical neoplasia among HPV16-seropositive subjects and DQA1*0501-DQB1*0301 (DQ7) with an increased risk among HPV16-seronegative subjects.

Family history of cancer is a risk factor for squamous cell carcinoma of the head and neck in Brazil: a case-control study

To determine the role of familial factors in head and neck cancer, we analysed data from a hospital-based case-control study of squamous cell carcinoma of the head and neck in Brazil. There were 754 cases of squamous cell carcinoma of the head and neck (SCCHN) and 1,507 age- and gender-matched hospital-based controls with non-malignant diseases. Subjects provided information on the occurrence of cancer in first-degree relatives, as well as about other risk factors, including tobacco and alcohol consumption. Relative risks (RRs) were estimated for developing mouth, pharynx and larynx cancer when cancers in relatives were observed. RRs were adjusted for age, sex, city of admission and alcohol and tobacco consumption. The RR for developing SCCHN if a first-degree relative had cancer at any site was significantly elevated at 1.97. The RR was 3.65 (95% CI: 1.97-6.76) if the relative had head and neck cancer. Significantly elevated risks for developing head and neck cancer were associated with siblings with head and neck cancer (RR = 8.57) and, to a lesser extent, with fathers with head and neck cancer (RR = 2.49). There was no significantly increased risk associated with mothers with head and neck cancer, but these tumours were rare among mothers. Our data show that familial, possibly genetic, factors are important in the aetiology of head and neck cancer.

The ecology and pathology of Epstein-Barr virus

Epstein-Barr virus achieves its ubiquitous and uniform epidemiological distribution by a dual strategy of latency to guarantee lifelong persistence and intermittent replication to guarantee transmission. These two functions appear to dictate residence in different cell types: latency in B lymphocytes and replication in epithelial cells. Both of these cell compartments are potential sites for EBV-associated malignancies.

HLA-A2 allelic microvariants in nasopharyngeal carcinoma

HLA-A2-positive nasopharyngeal carcinoma (NPC; n = 38) and normal control (n = 51) populations were analysed by high-resolution oligotyping to identify A2 allelic microvariants. Within the control group, A*0207 was found to be the most common allele, accounting for 50% of the A2 frequency in normals. In contrast, this allele was found to be present in only 23% of NPC cases, suggesting a protective effect. Of these 9 NPC patients with A*0207, all were associated with B46, unlike in the control group, where it can be found associated with non-B46 antigens. Another allele, A*0201, which was thought to be protective against NPC was in fact present in 39.5% of NPC patients, more than twice the frequency in controls. These data confirm that A*0201 is not a protective allele for NPC, and other factors such as the A*0207, non-B46 haplotype are of greater importance.

Immune regulation in Epstein-Barr virus-associated diseases

Epstein-Barr virus (EBV) is a member of the human herpesvirus family and, like many other herpesviruses, maintains a lifelong latent association with B lymphocytes and a permissive association with stratified epithelium in the oropharynx. Clinical manifestations of primary EBV infection range from acute infectious mononucleosis to an asymptomatic persistent infection. EBV is also associated with a number of malignancies in humans. This review discusses features of the biology of the virus, both in cell culture systems and in the natural host, before turning to the role of the immune system in controlling EBV infection in healthy individuals and in individuals with EBV-associated diseases. Cytotoxic T cells that recognize virally determined epitopes on infected cells make up the major effector arm and control the persistent infection. In contrast, the options for immune control of EBV-associated malignancies are more restricted. Not only is antigen expression restricted to a single nuclear antigen, EBNA1, but also these tumor cells are unable to process EBV latent antigens, presumably because of a transcriptional defect in antigen-processing genes (such as TAP1 and TAP2). The likelihood of producing a vaccine capable of controlling the acute viral infection and EBV-associated malignancies is also discussed.

No association between HLA-DQ and -DR genotypes with nasopharyngeal carcinoma in southern Chinese

The pathogenesis of nasopharyngeal carcinoma (NPC) is multifactorial. Associations have been reported between HLA and NPC. We studied the HLA-DR and -DQ regions on the molecular level in 136 persons (51 NPC patients and 85 healthy controls) from southern China, a particularly high-prevalence area for NPC. Restriction fragment-length polymorphism (RFLP) was used to genotype the MHC class II DR beta, DQ alpha, and DQ beta regions of the subjects. Polymerase chain reaction (PCR) using sequence-specific primer (SSP) for DQ beta genes was also performed. By RFLP, no significant difference was observed with respect to DRB, DQA, and DQB genes. By PCR SSP typing, we confirmed that there was no significant difference between NPC patients and controls with respect to DQ beta alleles. Our study suggests that HLA-DQ and -DR genes are not associated with NPC in southern Chinese and there may be other gene loci that predispose them to have such a high prevalence of the disease.

Linear epitopes of the replication-activator protein of Epstein-Barr virus recognised by specific serum IgG in nasopharyngeal carcinoma

The linear antigenic epitopes of the Epstein-Barr virus replication activator protein (ZEBRA), recognised by specific serum IgG in nasopharyngeal carcinoma (NPC), were determined. This was achieved by synthesizing the entire amino acid sequence of ZEBRA as a set of 29, 22-residue peptides with an overlap of 14 amino acids. The ZEBRA peptides were tested in enzyme-linked immunosorbent assay (ELISA) for IgG binding in sera from 37 selected NPC patients who had IgG antibodies to the native ZEBRA protein. The most immunogenic epitope was peptide 1 at the amino-terminal end with 36 of the sera reactive against it. Further analysis of peptide 1, using the multipin peptide-scanning technique, defined a 10-amino-acid sequence FTPDPYQVPF, which was strongly bound by IgG. Two other regions of ZEBRA were also identified as immunodominant IgG epitopes, namely peptide 11 (amino acids 82-103) and peptide 19/20 (amino acids 146-175) with 8-13 of the NPC sera reactive against the peptides. The number of peptides reactive with individual NPC serum varies from 1 to 6 or more and there is some correlation between a greater number of peptide (at least 4) bound and a higher (at least 1:40) titre of serum IgA to viral capsid antigen. The immunodominant ZEBRA peptide 1 could be utilised in IgG ELISA for the detection of NPC.

Cancer incidence in Asian migrants to New South Wales, Australia

Cancer incidence during 1972-90 in Asian migrants to New South Wales, Australia, is described. Overall cancer incidence was lower than in the Australia born in most migrant groups, and this reached significance in migrants born in China/Taiwan, the Philippines, Vietnam and India/Sri Lanka, and in male migrants born in Indonesia. For the majority of cancers, rates were more similar to those in the Australia born than to those in the countries of birth. For cancers of the breast, colorectum and prostate, rates were relatively low in the countries of birth, but migrants generally exhibited rates nearer those of the Australia born. For cancers of the liver and cervix and, in India/Sri Lanka-born migrants, of the oral cavity, incidence was relatively high in the countries of birth but tended to be lower, nearer Australia-born rates, in the migrants. For these cancers, environmental factors related to the migrant's adopted country, and migrant selection, appeared to have a major effect on the risk of cancer. For certain other cancers, incidence was more similar to that in the countries of birth. Nasopharyngeal cancer, and lung cancer in females, had high rates in both the countries of birth and in migrants to Australia. Nasopharyngeal cancer rates were highest in China/Taiwan and Hong Kong-born migrants, and were also significantly high in migrants from Malaysia/Singapore, Vietnam and the Philippines. Rates of lung cancer were significantly high in women born in China/Taiwan, and the excess was greater for adenocarcinoma than for squamous cell carcinoma. Melanoma had low rates in both the migrants and in the countries of birth. For these cancers, it was probable that genetic factors, or environmental factors acting prior to migration, were important in causation.