Common variations in TERT-CLPTM1L locus are reproducibly associated with the risk of nasopharyngeal carcinoma in Chinese populations

Associations between single nucleotide polymorphisms (SNPs) at 5p15 (TERT-CLPTM1L) and multiple cancer types have been reported. We examined whether polymorphisms in the TERT-CLPTM1L locus were related to the risk of developing nasopharyngeal carcinoma (NPC) among Chinese populations. In the first stage, 26 tag SNPs were genotyped in a Guangxi population (855 patients and 1036 controls). In the second stage, the SNPs, which showed significant association, were further genotyped in a Guangdong population (997 patients and 972 controls). Functional analyses were conducted to verify the biological relevance of the associated polymorphism. In the 1st stage, four SNPs (rs2736098, rs2735845, rs402710, and rs401681) were significantly associated with the risk of developing NPC. After the 2nd stage validation, rs2735845 and rs401681 were independently associated with the risk of developing NPC in the additive model (rs2735845, OR = 1.19, 95% CI = 1.04–1.37, P = 0.011; rs401681, OR = 0.85, 95% CI = 0.74–0.99, P = 0.034). Furthermore, we observed higher CLPTM1L messenger RNA levels in fetal mesenchymal stem cells from the rs2735845 G allele carriers compared with that from non-carriers. In addition, using an immunohistochemistry assay, we observed higher TERT and CLPTM1L levels in NPC tissues compared with that in non-cancerous nasopharyngeal tissues. Our findings suggest that polymorphisms in the TERT-CLPTM1L locus may play a role in mediating the susceptibility to NPC in Chinese populations.     

The protective role of polymorphism MKK4-1304 T>G in nasopharyngeal carcinoma is modulated by Epstein-Barr virus' infection status

MKK4 is a candidate tumor suppressor, which acts as a critical mediator of Epstein-Barr Virus (EBV)-induced c-Jun N-terminal kinase (JNK) activation. Functional polymorphism MKK4 -1304T>G has been showed to be protective in colorectal cancer or lung cancer. We hypothesized that genetic variants in the MKK4 promoter were associated with the risk of nasopharyngeal carcinoma (NPC). Two common polymorphisms in MKK4, -1304T>G and -1044A>T were genotyped in two independent case-control panels of Eastern and Southern Chinese populations, totally containing 1237 NPC and 1328 controls. We found that compared to the most common -1304TT genotype, carriers of variant genotypes (-1304TG+GG) were associated with a significantly reduced risk for NPC in total subjects (adjusted OR = 0.78; 95%CI = 0.67-0.94). Further stratification analysis showed that the protective effect was more pronounced in EBV negative status (adjusted OR = 0.51; 95%CI = 0.41-0.68) but restrained in those with EBV infection (adjusted OR = 1.05; 95%CI = 0.88-1.26), and that the -1304GG variant genotypes interacted with EBV negative status on reducing cancer risk (p = 0.011). However, no significant association was observed between the -1044A>T polymorphism and risk of NPC. Our data suggest that the protective role of genetic variant MKK4 -1304T>G is restrained in NPC with EBV infection. These findings implicate the role of EBV and MKK4 -1304 T>G interaction as a causative factor for the NPC.     

Variants at chromosome 20 (ASIP locus) and melanoma risk

Agouti signaling protein (ASIP) locus on chromosome 20q11 is implicated, as shown by genome‐wide association studies, in phenotype variation and melanoma risk. We genotyped 837 melanoma cases and 1,154 controls for 21 single nucleotide polymorphisms (SNPs) informative for 495 polymorphisms at the locus. Our data showed an increased risk of melanoma (odds ratio [OR] 1.27, 95% confidence interval [95% CI] 1.03–1.57) in carriers of the rs4911414 variant, located 120 kb upstream of ASIP. The main effect of rs4911414, as reported previously, was in tandem with a 10 kb adjacent polymorphism rs1015362; two constituted risk‐associated haplotype/diplotype. Except for rs1015363, none of the 12 tagging SNPs, genotyped to cover 239.9 kb region with polymorphisms linked to rs4911414 and rs1015362, were associated with melanoma. Our data confirmed a previous association of melanoma risk (OR 1.82, 95% CI 1.37–2.41) with rs4911442, located in intron 5 of the nuclear receptor coactivator 6 (NCOA6) gene. The rs910871, one of the six variants, genotyped to cover NCOA6, showed an association with melanoma risk (OR 1.33, 95% CI 1.04–1.70). Both, rs4911442 and rs910871 were in moderate linkage with a, previously reported, risk‐associated rs910873 polymorphism. A haplotype from the variants within NCOA6 showed an association with risk of melanoma (OR 1.49, 95% CI 1.17–1.88). Interaction between risk‐associated polymorphisms and previously genotyped melanocortin receptor 1 (MC1R) variants, in our study, was not statistically significant. Nevertheless, the carriers of the variant alleles over the background of MC1R variants were at a higher risk than the carriers not enriched for MC1R variants. Our data confirmed the association of different variants at chromosome 20q11 with melanoma risk.     

Association of ERCC1 polymorphisms and susceptibility to nasopharyngeal carcinoma

The normal function of excision repair cross complementing group 1 (ERCC1) is essential for maintaining genomic integrity and preventing cellular neoplastic transformation, and multiple studies have reported an association between ERCC1 polymorphisms and increased risk of cancers. To test whether the genetic variants of ERCC1 gene modify the risk of nasopharyngeal carcinoma (NPC), we compared the 8092 C > A and 19007 C > T single nucleotide polymorphisms (SNPs) and the haplotypes of ERCC1 between 267 patients with NPC and 304 healthy controls. Linkage disequilibrium was observed between the two SNPs loci (D' = 0.861). Significant differences of allele frequencies were found for ERCC1 8092C > A between the cases and controls. Individuals with 8092 C allele showed 1.411-fold (OR = 1.411, 95% CI, 1.076-1.850, P = 0.014) increased risk of developing NPC, and the CC haplotype was associated with a significantly increased risk of NPC (OR = 1.712; 95% CI, 1.211-2.421; P = 0.013). No interactions were found between 8092C > A polymorphism and genders, smoking status and alcohol consumption. These results suggested that the polymorphism of ERCC1 8092 C > A might be a contributing factor in the development of NPC in Chinese population.     

鼻咽癌发生发展过程中EBER1表达的研究

目的：探讨ＥＢＶ与鼻咽癌发生发展的关系及其病理学意义。方法：应用原位杂交技术检测５０例鼻咽癌石蜡切片组织中ＥＢＥＲ１的表达及分布状况。结果：正常鼻咽粘膜上皮及其单纯性增生、鳞状化生上皮ＥＢＥＲ１表达均阴性,鼻咽癌组织中表达率为９８％（４９／５０）,且在转移灶中不丢失。鼻咽异型增生上皮亦可表达ＥＢＥＲ１阳性信号（１６／２０）,结论：ＥＢＶ与鼻咽癌关系密切,ＥＢＶ可能在鼻咽上皮的恶性转化过程中起重要作用,鼻咽上皮的异型性改变尤其是ＥＢＥＲ１阳性者可认为是癌前病变,随访监测可能有利于早期发现鼻咽癌。     

Human genetic variants of homologous recombination repair genes first found to be associated with Epstein-Barr virus antibody titers in healthy Cantonese

Epstein-Barr virus (EBV) infection is a major risk factor for nasopharyngeal carcinoma (NPC). Despite high prevalence of infection among the general population worldwide, only a small proportion of infected individuals presents with seropositivity for EBV-specific IgA antibodies. This seropositive subgroup of EBV carriers has an elevated cumulative risk for NPC during their lifetime. Previous studies reported that the host homologous recombination repair (HRR) system participates in EBV lytic replication, suggesting a potential mechanism to influence EBV reactivation status and thus seropositivity. To investigate whether genetic variants of HRR genes are associated with the serostatus in a healthy population, we investigated the association between seropositivity for anti-VCA-IgA and 156 tagging SNPs in 35 genes connected with HRR in an observational study among 755 healthy Cantonese speakers in southern China. Six variant alleles of MDC1, RAD54L, TP53BP1, RPA1, LIG3 and RFC1 exhibited associations with seropositivity (p(trend) from 0.0085 to 0.00027). Our study provides evidence that genetic variation within the HRR might affect an individual's propensity for EBV seropositive status of anti-VCA IgA antibody.     

Specific latent membrane protein 1 gene sequences in type 1 and type 2 Epstein-Barr virus from nasopharyngeal carcinoma in Hong Kong

We reported previously that a characteristic Epstein-Barr virus latent membrane protein 1 (EBV-LMP1) gene was associated with nasopharyngeal carcinoma (NPC) in Hong Kong. It showed a 30 bp deletion at the carboxyl terminus with specific amino acid substitution Asp at codon 335 with reference to Gly in B95-8 LMP1. This deletion variant Asp335 was present in over 90% of NPC biopsy specimens. The present study attempted to determine the whole encoding sequence of the LMP1 gene in different EBV isolates from NPC, and its relation with EBV types. We found that 92% (34/37) of primary NPC tumours harboured EBV-1 and possessed the LMP1 deletion variant, of which 86% were Asp335 and 6% were Gly335. EBV-2 was present in 8% (3/37) of tumours and all contained the retention variant of the LMP1 gene. Sequencing of the whole encoding region of the LMP1 gene revealed that the deletion variant Asp335 and deletion variant Gly335 carried similar sequences. They showed 43 common nucleotide substitutions in 41 codons with reference to B95-8. The retention variant showed 52 base changes in 46 codons compared with B95-8. The amino acid alterations in both the deletion and retention variants were mostly clustered at the transmembrane domain of the protein. Furthermore, half of the substitutions were common to both variants, suggesting a common evolutionary selection pressure. Nonetheless, the 2 LMP1 variants showed differences in nucleotide alterations and were associated with different EBV types, suggesting the presence of 2 distinct EBV strains in Hong Kong NPC. Int. J. Cancer 76:399–406, 1998.© 1998 Wiley-Liss, Inc.     

Generation of monoclonal antibodies against Hong Kong nasopharyngeal carcinoma-associated Epstein-Barr virus latent membrane protein 1 (LMP1)

A panel of monoclonal antibodies specific to Hong Kong Chinese nasopharyngeal carcinoma (NPC)-associated Epstein-Barr virus (EBV) latent membrane protein 1 (LMP1) variants has been generated. These monoclonal antibodies not only differentiate the Hong Kong Chinese NPC-associated LMP1 variants from the prototype B95-8 LMP1, derived from Caucasian infectious mononucleosis, but also differentiate the 2 highly homologous LMP1 deletion variants commonly found in Hong Kong primary NPC. The predominant deletion type variant, DV-Asp335, is characterized by an aspartic acid at residue 335 located in the cytoplasmic C-terminal region, whereas the other minor deletion variant, DV-Gly335, has a glycine in the same residue position. 335D is hitherto found predominantly in LMP1 of the China 1 strain in association with NPC in the Chinese populations located in southern China and Malaysia. These antibodies, which are applicable in ELISA, immunofluorescence, immunoprecipitation, immunoblotting and immunohistochemistry on paraffin sections, are the first variant-specific anti-LMP1 monoclonal antibodies produced, and will be useful in investigating the functional significance of 335D in NPC.     

Cancer risk to the gastric corpus in Japanese, its correlation with interleukin-1beta gene polymorphism (+3953*T) and Epstein-Barr virus infection

Polymorphisms of interleukin-1 (IL-1) genes have been reported to modify the risk of gastric carcinoma (GC) in Caucasians. The significance of IL-1beta gene polymorphisms was evaluated in Japanese GC patients with or without infection of Helicobacter pylori and Epstein Barr virus (EBV) with special reference to the topographic features of GC. IL-1beta gene polymorphisms at positions -511 and +3953 were evaluated by PCR-RFLP and a penta-allelic polymorphism of IL-1RA by PCR in healthy controls (n = 103) and GC (n =140; corpus 95, antrum 45). EBV-infection was determined in the neoplastic tissues by EBER1 in situ hybridization, and H. pylori infection in nonneoplastic gastric mucosa by PCR targeting of the H. pylori urease A gene. GC consisted of EBV-associated (n = 24) and EBV-negative (n = 116) patients, whereas H. pylori infection was positive in 130 cases. Among IL-1beta gene polymorphisms, genotype IL-1beta+3953 C/T was more frequent in the EBV-negative (21%) and corpus GC (23%) patients, compared to the controls (10%), respectively, although there was no genotype IL-1beta+3953 T/T in either group. Thus, the effect of IL-1beta+3953 T was statistically significant in logistic regression models adjusted for age in EBV negativity (odds ratio [OR] 2.27, 95% confidence interval [CI] 1.02-5.05) and in the corpus GC (2.70, 1.19-6.12) with highest OR 3.55 (1.54-8.23) in EBV-negative corpus GC. There was no significant influence of IL-1 gene polymorphism in EBV-associated GC, but it occurred predominantly in the corpus (24/24) compared to EBV-negative GC (71/116) (p = 0.00002). There was no correlation between H. pylori infection and IL-1 gene polymorphism in GC. The cancer risk of the gastric corpus in Japanese is influenced by IL-1beta+3953 polymorphisms. On the other hand, the risk of EBV-associated GC, which occurs predominantly in the corpus, is not influenced by this pro-inflammatory polymorphism.     

The xeroderma pigmentosum group C gene polymorphisms and genetic susceptibility of nasopharyngeal carcinoma

Aims. Nasopharyngeal cancer (NPC) is a multi-factorial disease, and the genetic background may be a crucial etiologic factor. The xeroderma pigmentosum complementation group C (XPC) is mainly involved in DNA damage repair, and the sequence variants in XPC gene may modulate DNA repair capacity and consequently lead to an individual's susceptibility to NPC. The aims of this study were to examine the association between XPC Val499Ala, Lys939Gln, PAT polymorphisms and the genetic susceptibility of nasopharyngeal carcinoma (NPC) in Chinese population. Methods. We analyzed the three XPC gene polymorphisms in 153 patients with NPC and 168 age- and sex-matched controls in a Chinese population, using a polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) procedure. Results. There were significant differences in the genotype and allele distribution of XPC Val499Ala among cases and controls. The 499Val allele carriers were associated with a significantly increased risk of NPC compared with the non-carriers (OR=1.603; 95%CI, 1.160∼2.216, p=0.005). Consistent with the results of the genotype analysis, the 499Val/939Lys/PAT-haplotype was associated with a significantly increased risk of NPC as compared with the 499Ala/939Lys/PAT-haplotype (OR=1.901; 95% CI, 1.284∼2.814, p=0.002).The interaction between the Val499Ala polymorphism and gender or smoking status did not been found in NPC risk. Conclusions. Our data demonstrated that XPC 499Val allele and its haplotype were strongly associated with NPC, which indicated that Val499Ala polymorphism may be a contributing factor in the NPC development.     

Epstein-barr virus genotypes in NPC biopsies from North Africa

The genotypes of Epstein-Barr virus (EBV) were investigated in North African nasopharyngeal carcinoma (NPC) biopsies, nasopharyngeal chronic inflammation (NCI) biopsies, and saliva of healthy individuals from Algeria and Tunisia where there is an intermediate incidence of NPC. The prevalence of A-type virus in NPC, NCI biopsies and saliva of healthy individuals was found in these regions by means of a PCR assay. Restriction enzyme polymorphism analysis by Southern blotting revealed that all North African EBV variants have a conserved restriction site on BamHI W'-1′ and XhoI LMP gene. No additional BamHI enzyme site on the BamHI-F fragment was observed; however, the presence of an extra BamHI site on the BamHI-H fragment giving 2 H1 and H2 fragment-like EBV M-ABA strains was found. All EBV strains present in NPC or NCI biopsies at all ages were homogeneous in these polymorphisms and no correlation was observed between the EBV genotypes from NPC patients and clinical stages of the cancer. These characteristics revealed a significant difference between the EBV variants common in Chinese NPC and those in North African NPC.     

Multigene pathway‐based analyses identify nasopharyngeal carcinoma risk associations for cumulative adverse effects of TERT‐CLPTM1L and DNA double‐strand breaks repair

The genetic etiology of nasopharyngeal carcinoma (NPC) and mechanisms for inherited susceptibility remain unclear. To examine genetic risk factors for NPC, we hypothesized that heritable risk is attributable to cumulative effects of multiple common low‐risk variants. With the premise that individual SNPs only confer subtle effects for cancer risk, a multigenic pathway‐based approach was used to systematically examine associations between NPC genetic susceptibility with SNPs in genes in DNA repair pathways and from previously identified cancer genome‐wide association study analyses. This case–control study covers 161 genes/loci and focuses on pathway‐based analyses in 2,349 Hong Kong individuals, allowing stratification according to NPC familial status for meaningful association analysis. Three SNPs (rs401681, rs6774494 and rs3757318) corresponding to TERT/CLPTM1L (OR 95% CI = 0.77, 0.68–0.88), MDS1‐EVI1 (OR 95% CI=0.79 0.69–0.89) and CCDC170 (OR 95% CI = 0.76, 0.66–0.86) conferred modest protective effects individually for NPC risk by the logistic regression analysis after multiple testing adjustment (p_Bonferroni < 0.05). Stratification of NPC according to familial status identified rs2380165 in BLM (OR 95% CI = 1.49, 1.20–1.86, p_Bonferroni < 0.05) association with family history‐positive NPC (FH+ NPC) patients. Multiple SNPs pathway‐based analysis revealed that the combined gene dosage effects for increasing numbers of unfavorable genotypes in TERT‐CLPTM1L and double‐strand break repair (DSBR) conferred elevated risk in FH+ and sporadic NPC patients (ORs per allele, 95% CIs = 1.37, 1.22–1.55, p_Bonferroni = 5.00 × 10^?6; 1.17, 1.09–1.26, p_Bonferroni = 4.58 × 10^?4, respectively, in TERT/NHEJ pathways). Our data suggested cumulative increased NPC risk associations with TERT‐CLPTM1L and DSBR pathways contribute to genetic susceptibility to NPC and have potential translational relevance for patient stratification and therapeutics.     

Polymorphisms of Epstein-Barr virus BHRF1 gene, a homologue of bcl-2

Background and Objective: EBV BamHI fragment H rightward open reading frame 1 (BHRF1), the Epstein-Barr virus (EBV) early gene, is structurally and functionally homologous to the oncogene bcl-2 and may play an important role in the development of EBV-associated tumors. To characterize the polymorphisms of BHRF1 in EBV-associated tumors, we analyzed the sequences of BHRF1 in isolates from nasopharyngeal carcinoma (NPC) and EBV-associated gastric carcinoma (EBVaGC) biopsies as well as throat washing (TW) samp...     

Association of IL-1 polymorphisms and IL-1 serum levels with susceptibility to nasopharyngeal carcinoma

Previous studies demonstrated that the polymorphism of interleukin-1 (IL-1) produce alterations of the protein expression and may contribute to oncogenetic processes. The aim of this study was to investigate the relationship between IL-1A gene polymorphisms and NPC susceptibility and the influence of on IL-1α serum levels in cases versus controls. To test whether the genetic variants of IL-1A gene modify the risk of nasopharyngeal carcinoma (NPC), we compared the -889C/T and rs3783553 polymorphisms between 248 patients with NPC and 296 healthy controls using polymerase chain reaction-restriction fragment length polymorphism. Serum IL-1α levels were measured by enzyme-linked immunosorbent assay. The rs3783553 (TTCA insertion or deletion) polymorphism of the IL-1A gene was significantly associated with the susceptibility to NPC. The variant homozygote genotype +/+ was associated with a significantly reduced risk of NPC as compared with the wild homozygote -/- genotype, and the serum IL-1α levels were significantly lower in individuals with homozygous +/+ genotypes. No association was found between the -889C/T polymorphisms and risk of NPC, and no statistically significant differences were found between rs3783553 polymorphism and clinical pathology indices. The IL-1A rs3783553 polymorphism might contribute to a risk of developing NPC by affecting the serum IL-1α secretion in the Chinese population.     

EBV specific antibody-based and DNA-based assays in serologic diagnosis of nasopharyngeal carcinoma

We assessed 5 EBV specific assays for their capacity to effect serologic diagnosis of suspected NPC. The assays were the immunofluorescent assays, VCA IgA and EA IgA, the enzyme-linked immunosorbent assays specific for EBNA 1 IgA or zta IgG and an EBV DNA assay. Serum samples were taken from 218 symptomatic NPC patients presenting consecutively at a public hospital in Hong Kong, 51 of whom were subsequently diagnosed as having NPC; 4 had EBV-associated lung cancer with similar serology as NPC. The remaining patients included 23 who had other cancers and 140 who had other diseases. Objectives of serodiagnosis under such clinical settings, therefore, are to both exclude and predict a diagnosis of NPC. None of the assays individually can meet both requirements adequately, however. The difficulty was best overcome by combining EBNA 1 IgA and zta IgG. It was shown that 68.3% of the patients gave a confirmed test results, negative or positive, by both tests. A confirmed negative result was associated with a negative predictive value of 99.1%, providing a clear indication to exclude a diagnosis of NPC; a confirmed positive result was associated with a positive predictive value of 86.8%, providing a clear indication to proceed with diagnostic work-up of NPC. The remaining patients gave equivocal test results, being positive for one or the other test, which were associated with a positive predictive value of 43.3% and 24.2%, respectively.     

Dysfunction of mitochondria due to environmental carcinogens in nasopharyngeal carcinoma in the ethnic group of Northeast Indian population

Nasopharyngeal carcinoma (NPC) is a rare cancer worldwide, but in India, NPC is uncommon in its subcontinent except in the north-eastern part of the country. NPC is thought to be caused by the combined effects of environmental carcinogens, genetic susceptibility and Epstein-Barr virus (EBV). This is the first study that aimed to examine the selected risk factors, mostly dietary, viral environmental, metabolic gene polymorphisms, mitochondrial DNA (mtDNA) copy number variation and their risk, in subjects who are highly prone to NPC in the ethnic groups of Northeast India, which has included cases, first-degree relatives and controls. The cases and controls were selected from three ethnic groups (Manipuri, Naga and Mizo) of Northeast India with high prevalence of NPC. This case–control family study includes 64 NPC patients, 88 first-degree relatives and 100 controls having no history of cancer. PCR-based detection was done for EBV–latent membrane protein 1 (LMP1) gene and glutathione S-transferase Mu 1 (GSTM1)–glutathione S-transferase theta 1 (GSTT1) polymorphism. A comparative ΔCt method was used for the determination of mtDNA content. An increased risk of 2.00–6.06-folds to NPC was observed with those who intake smoked meat and fish, salted fish and fermented fish; betel nut chewers; tobacco smokers; alcohol drinkers; and those who have kitchen inside the living room, glutathione S-transferase null genotype and EBV infection. The risk of NPC increased in cases with decreased mtDNA copy number (P _trend?=?0.007). A significant difference between GST null genotypes and EBV infection with mtDNA content was found in the cases (P?<?0.0001). The understandings of environment–genetic risk factors and their role in the etiology of NPC are helpful as preventive measures and screening.     

Intake of Cantonese-style salted fish as a cause of nasopharyngeal carcinoma

Ho (1971) of Hong Kong first proposed consumption of Cantonese-style salted fish, a traditional food among southern Chinese, as a possible risk factor for nasopharyngeal carcinoma (NPC) in this high-risk population. Four case-control studies have examined Ho's hypothesis; all results are supportive. The most convincing evidence of a causal association between intake of salted fish and NPC derives from a recent case-control study of young Hong Kong Chinese. It is estimated that over 90% of NPC cases under age 35 in Hong Kong are due to intake of this food during childhood. Preliminary experimental data on Cantonese-style salted fish indicate that N-nitroso compounds may be involved in the carcinogenicity of this human food.     

ASSOCIATION OF pIgR POLYMORPHISMS WITH NASOPHARYNGEAL CARCINOMA

Objective： Epstein-Barr virus （EBV） associated nasopharyngeal carcinoma （NPC） is an important squamous cell cancer endemic in southern China and Southeast Asia. pIgR （polymeric immunoglobulin receptor） gene plays central roles during immune responses and EBV inflammatory and therefore is a good candidate susceptibility gene for NPC. This study is to evaluated potential associations between pIgR gene and NPC susceptibility. Methods： Sequencing was used to identify multiple single nucleotide polymorphisms （SNPs） within the exon regions of pIgR in Guangdong population. Four SNPs were genotyped in 528 NPC patients and 408 normal individuals to perform case-control study. Results： There was no statistical difference in the allele frequencies of each SNP （P〉0.05）. After categorized into 2 groups by age of 45 y, in the group of age below 45 the minor allele T frequency of C888oT was 7%, whereas 4% in controls, with significant difference （P〈0.05）. The Odds Ratio （OR=1.84） also showed higher risk of NPC with individuals carried the minor alleles. Conclusion： The result has proved that SNP C8880T is associated with NPC susceptibility and pIgR gene might play a certain role in oncogenesis and development of NPC.