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Objective: Regulatory T cells (Tregs) are critical factors that impair antitumor immunity. Epstein–Barr virus (EBV)-encoded latent membrane protein 1 (LMP1) is one of the most pathogenic factors in nasopharyngeal carcinoma (NPC). However, the role of EBV-encoded LMP1 in regulating Treg generation in NPC remains unclear. Materials and Methods: The in vitro stability of activated Tregs (aTregs) influenced by LMP1 was analyzed by flow cytometry. The inhibitory effects of LMP1-HONE1 antigen-induced aTregs on tumor-associated antigen (TAA)-specific T cells were analyzed in vitro and in vivo. Finally, the expression of LMP1, Foxp3, and enhancer of zeste homolog 2 (EZH2) were analyzed in samples from 86 NPC patients by immunohistochemistry and immunofluorescence. Results: LMP1 upregulated the expression of EZH2, which increased the stability of aTregs in vitro. EZH2 inhibitor, DZnep, depleted LMP1-HONE1 antigen-induced aTregs in vitro and led to potent TAA-specific T cell antitumor immunity in vivo. In NPC tissues, LMP1 expression level was positively correlated with the number of EZH2+ Tregs, which was positively correlated with clinical stage and overall survival. Conclusions: EZH2 is essential for maintaining the stability and inhibitory functions of aTregs that are induced by EBV-encoded LMP1 in NPC
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Non-Hodgkin’s Lymphoma is a haematological malignancy with various etiological factors and one among them is Epstein Barr Virus. The expression of Epstein-Barr virus in Non-Hodgkin’s lymphoma can be identified by immunohistochemistry for detection of Epstein-Barr virus latent membrane protein (LMP-1). In our study, we are trying to clarify the extent of expression LMP-1 in our population. This can be used as a prognostic marker and for therapeutic interventions targeting EBV encoded proteins. We wanted to determine the proportion of LMP1 (EBV marker) expression in Non-Hodgkin’s Lymphoma and evaluate the association of LMP1 expression in B cell and T cell type of NHL.METHODSThis is a cross sectional analytical study conducted at Department of Pathology, Govt. Medical College, Kottayam, from December 2017 to May 2019. A total of 67 cases were studied. All of them were histopathologically diagnosed Non-Hodgkin’s Lymphoma specimens received in the Department of Pathology, Govt. Medical College, Kottayam, during the study period of 18 months. NHL was subtyped into B cell type and T cell type. LMP-1 immunohistochemistry was done on all cases to assess its expression. Then analysis was done using SPSS software and strength of association between LMP 1 positivity and cell type was calculated using Chi square test and Fisher’s exact test.RESULTSMean age of Non-Hodgkin’s lymphoma is 57.82 +/- 7.4 in this study. Minimum age is 2 years and maximum age is 89 years. The present study had 10.4 % LMP 1 positive cases. Of which there were 6% moderately stained positive cases, 3% of weakly stained cases and 1.5% cases of intensely stained cases. Among NHL 86.6% cases were B cell lymphoma and 13.4% cases of T cell lymphoma. And they had a LMP 1 positivity of 10.3% and 11.1 % respectively. But there was no significant association between LMP 1 positivity and cell type according to our study.CONCLUSIONSThe present study was done to determine the proportion of LMP 1 expression in Non-Hodgkin’s Lymphoma and to find out whether there is any association between LMP1 expression in B cell and T cell type of NHL. LMP 1 was positive in 10.4% of NHL and there was no association between LMP 1 positivity in B cell and T cell Lymphoma. This suggest that EBV might play a role in pathogenesis of NHL.
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Latent membrane protein 1 (LMP1) as a product of human herpesvirus 4 encoding is closely related to the occurrence and development of various tumors. However, the articles related to hematological tumors are rare. This review focuses on the correlation between LMP1 and hematological tumors and the progress of treatment.
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AIM: To investigate the effects of TNF receptor-associated death domains (TRADD) of latent membrane protein 1 (LMP1) on the proliferation of nasopharyngeal cancer SP18 cells.METHODS: The SP18-LMP1 cells and SP18-LMP1TRADD cells, which expressed LMP1 and LMP1 TRADD proteins, respectively, were established.The proliferation of SP18 cells affected by LMP1TRADD was detected by cell counting to analyze the cell growth curve, and by colony formation assay, soft agar formation assay, and flow cytometry.Moreover, the expression profile of differential genes between SP18-LMP1 cells and SP18-LMP1TRADD cells was analyzed by gene chips.RESULTS: The cell growth curve, and the results of colony formation and soft agar formation displayed that the growth velocity and colony forming ability of SP18-LMP1 cells were stronger than those of SP18-LMP1TRADD cells (P<0.01).The results of flow cytometry analysis showed that the proliferation index of SP18-LMP1 cells was higher than that of SP18-LMP1TRADD cells (P<0.01).Sixty-three differentially expressed genes associated with cell proliferation were screened out, in which 33 genes were up-regulated and 30 were down-regulated in the SP18-LMP1TRADD cells.CONCLUSION: TRADD active region is an important functional site of LMP1 to promote the proliferation of SP18 cells.LMP1 may improve the cell proliferation index and induce the proliferation of SP18 cells through TRADD.
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Objective To explore the clinical significance of the serum Epstein-Barr virus determined nuclear antigen 1 (EBNA1)/latent membrane protein 1 (LMP1) in patients with extranodal NK/T-cell lymphoma,nasal type (ENKL).Methods The serum EBNA1 and LMP1 were detected by realtime PCR in 36 ENKL patients hospitalized in Beijing Tongren Hospital from August 2010 to August 2013.Twenty healthy volunteers were recruited as controls.Results The median serum EBNA1 was 1.9 × 104 (ranged from 0 to 11.0 × 104) copies/μl in ENKL patients and 8.0 (ranged from 0 to 43.8) copies/μl in healthy volunteers.The median serum LMP1 was 3.9 × 103 (ranged from 118.3 to 24.0 × 103) copies/μl in ENKL patients and 3.3 (ranged from 0 to 33.3) copies/μl in healthy volunteers.Both EBNA1 and LMP1 were higher in ENKL patients than healthy volunteers (all P ＜ 0.01).The median EBNA1 and LMP1 in ENKL patients posttreatment were 1.0 × 103 (ranged from 0 to 2.0 × 103) copies/μl and 300.8(ranged from 0 to 825.7) copies/μl respectively,which were both significantly decreased than pretreatment (all P ＜ 0.05).The EBNA1 and LMP1 were decreased in effective treatment group versus ineffective treatment group (P ＜0.05).The serum EBNA1 and LMP1 were positively correlated with lactic dehydrogenase (LDH) level (r =0.364,0.546 ; P =0.040,0.012).Conclusions (1) The measurement of EBNA1/LMP1 may be useful in evaluating the therapeutic effect.(2)The serum EBNA1/LMP1 may reflect the tumor load in ENKL patients.
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Objective To investigate the distribution characteristics of the Epstein-Barr virus (EBV)in lymphomas.Methods 438 cases of lymphomas were reclassified according to the WHO classification of lymphoma (2008).ALK1,CD3,CD5,CD7,CD10,CD15,CD20,CD23,CD30,CD43,CD56,CD68,CD79,CD99,CyclinD1,EMA,IgD,TdT,Vs38C and LMP-1 were detected by in situ hybridization of EBER and immunohistochemistry.Results In B cell lymphoma,T and NK cell lymphoma and Hodgkin' s lymphoma (HL),the positive rates of EBER were 5.4 ％ (14/261),16.5 ％ (19/115) and 59.7 ％ (37/62),respectively,and the positive rates of LMP-1 were 5.4 ％ (14/261),5.2 ％ (6/115) and 59.7 ％ (37/62).In DLBCL patients,EBER expression in the older group was significantly higher than that in the younger one [13.2 ％ (7/53) vs 1.2 ％ (1/81),P ＜ 0.05].The expression of EBER and LMP-1 were inconsistent in T and NK cell lymphomas,and the positive rate of EBER was significantly higher than that of LMP-1 (P ＜ 0.05).EBER was all positive in 5 cases of NK/T cell lymphoma-nasal type.The expression of EBER and LMP-1 were consistent in HL.Conclusion The EBV infection was associated with the classification of the lymphoma.The EBV infection was the highest in NK/T cell lymphoma-nasal type,and the next was in HL.Due to the consistency of EBER and LMP-1 expression in the HL,economically,LMP-1 may replace EBER as the indicator of EBV.EBV might play an important role in the occurrence and development of NK/T cell lymphoma-nasal type,HL and so on.
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Objective To investigate the expression of Epstein-Barr virus(EBV)-latent membrane protein 1 (LMP1) in chronic atrophic gastritis (CAG) with intestinal metaplasia and discuss its effect on gastric cancer.Methods Immunohistochemistry was used to examine the expression of EBV-LMP1 in 45 cases of chronic superficial gastritis(CSG),63 cases of CAG with intestinal metaplasia and 36 cases of gastric cancer.Results There was no expression of EBV-LMP1 in CSG and gastric cancer,while the positive rate of EBV-LMP1 in CAG with intestinal metaplasia was 36.5％ (23/63) and EBV-LMP1 was mainly stained in the cell nucleus.The expression of EBV-LMP1 in CAG with intestinal metaplasia was significantly higher than that in CSG and gastric cancer,and there was significant difference (P =0.000).Conclusions EBV-LMP1 is expressed in CAG with intestinal metaplasia.The expression of EBV-LMP1 is significantly higher than that in CSG and gastric cancer indicating that EBV infection in gastric carcinogenesis may play an important role in the early stages.
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Epstein-Barr virus (EBV) latent infection transforms B lymphocytes into proliferating lymphoblastoid cell lines (LCLs). EBV latent infection membrane protein 1 (LMP1) is required for EBV-mediated B lymphocyte transformation, and LMP1-induced NF-kappaB activation is essential for LCL survival. Previously, it was reported that the level of reactive oxygen species (ROS) and the expression of apoptosis signal-regulating kinase 1 (ASK1) are elevated in EBV-positive Burkitt's lymphoma (BL) cells, the potential role of ASK1 in LMP1-induced NF-kappaB activation was thus investigated in this study. In EBV-positive BL cells, ASK1 was highly expressed and activated. In addition, TRAF6-ASK1 interaction was significantly increased in EBV-positive BL cells. Interestingly, the expression of LMP1 alone facilitated ASK1 activation. The expression of a dominant negative ASK1 mutant (ASK1KM) strongly blocked LMP1-induced NF-kappaB activation. Furthermore, LMP1-induced NF-kappaB activation was significantly reduced in ASK1 knock out (ASK1-/-) mouse embryonic fibroblasts (MEFs). Taken together, these results demonstrate that ASK1 is activated by LMP1 and is critical for LMP1-induced NF-kappaB activation.
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Animals , Mice , B-Lymphocytes , Burkitt Lymphoma , Cell Line , Fibroblasts , Herpesvirus 4, Human , Lymphocyte Activation , MAP Kinase Kinase Kinase 5 , Membrane Proteins , NF-kappa B , Reactive Oxygen SpeciesABSTRACT
Objective: To investigate the effects of Epstein-Barr virus-latent membrane protein 1 (LMP1) and p38 mediating epithelial-mesenchymal transition of nasopharyngeal carcinoma (NPC), and to elucidate its relationship with tumor metastasis. Methods: The expression levels of E-cadherin, vimentin, LMP1 and p38 in NPC tissues and cell lines were detected by immunohistochemistry, immunocytochemistry, RT-PCR and Western blotting. The invasion and migration abilities of NPC cell lines were examined by Transwell assay. Results: The positive expression rates of E-cadherin in different NPC tissues and lymph node metastases were decreased (P<0.01), whereas the positive expression rates of vimentin and LMP1 were increased (P<0.001). The difference in the positive expression rate of p38 was not statistically significant (P<0.05).The expression of LMP1 was negatively associated with the expression of E-cadherin in NPC tissues (P<0.05). In cervical lymph node metastasis, the expression of LMP1, which had no association with the expression of E-cadherin (P<0.05), was associated with the expression of vimentin (P<0.05). The expressions of E-cadherin mRNA and protein were suppressed in CNE1-GL and CNE2Z cells, whereas the expressions of vimentin mRNA and protein were increased. The expression level of LMP1 protein was high in CNE1-GL and CNE2Z cells, and the expression level of p38 protein was high in CNE1-GL cells. Transwell assay showed that LMP1 could promote the migration and invasion abilities of NPC cells (P<0.001). Conclusion: LMP1 can induce EMT and enhance the metastatic potential of nasopharyngeal carcinoma. Copyright© 2011 by Tumor.
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AIM: To investigate the differential expression profile between nasopharyngeal carcinoma cell line CNE1 and its steady EBV-LMP1-transfected cell line CNE1-LMP1, and to explore the regulatory effect of LMP1 on oncomiRs expression in CNE1 cell line. METHODS: A microRNA array that targets 132 of the most well studied oncomiRs was used to detect the expression profile of CNE1 and CNE1-LMP1. qRT-PCR assay were used to verify the expression data detected by microarray. RESULTS: Among the restricted 132 miRNAs, 30 were detectable. Among which, 30 were expressed in CNE1-LMP1, 19 in CNE1 and 11 were specifically expressed in CNE1-LMP1. Among the 19 shared miRNAs, the expression level of 6 miRNAs (hsa-miR-19b, hsa-miR-17-3p, hsa-miR-22, hsa-miR-149, hsa-miR-150 and hsa-miR-188) elevated over two folds in CNE1-LMP1. No decrease in miRNA expression more than two folds was observed. qRT-PCR confirmed the expression difference of these six miRNAs (P<0.01). Among the 11 specifically expressed miRNAs in CNE1-LMP1, hsa-miR-122a showed the highest expression level surpassing the internal control sample. CONCLUSION: Our data suggest that LMP1 may play an important role in regulating the expression of miRNAs in tumor, which may be another important pathway employed by LMP1 in the development of nasopharyngeal carcinoma.
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AIM: To investigate the molecular mechanism of Epstein-Barr virus encoded latent membrane protein 1 regulated cellular proliferation in nasopharyngeal epithelial cells. METHODS: The nasopharyngeal epithelial cells NP69 were infected with RV-pLNSX (the empty vector) and RV-LMP1 retroviruses, respectively. Therefore, the NP69-pLNSX and NP69-LMP1 cell lines were established. Sequentially, cellular proliferation of NP69-pLNSX and NP69-LMP1 cells was compared to draw the cellular growth curve. The experiments of plate clone formation and forming of soft agar colony were conducted. Meanwhile, the differential expression of proteins were identified between NP69-pLNSX and NP69-LMP1 cell lines by proteomic methods, and the expression levels of partial identified proteins were verified. RESULTS: (1) LMP1 was able to accelerate cellular proliferation of nasopharyngeal epithelial cell NP69 (n=3, P<0.05). (2) Twenty two proteins (9 up-and 13 down-regulated) of LMP1 mediated regulation were identified from infected NP69 cell lines, and the differential expression of partial identified proteins was confirmed by Western blotting and fluorescent real-time quantitative RT-PCR. CONCLUSION: LMP1 probably mediates the regulation of vimentin protein and keratin 19 protein expression to promote cellular proliferation in NP69 cells.
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Objective:To evaluate the expression of vascular endothelial growth factor C(VEGF-C),Epstein-Barr virus(EBV) latent membrane protein 1(LMP1),cyclooxygenase-2 (COX-2) in nasopharyngeal carcinoma(NPC).Method:LMP1, COX-2 and VEGF-C were detects by immunohistochemical staining for 57 case NPC tissue.Result:The positives rates of LMP1,COX-2 and VEGF-C detected by immunohistochemical staining were 49.1%(28/57), 75.4%(43/57)and 59.6%(34/57), respectively. The expression of LMP1, COX-2 and VEGF-C were correlated to each1 other in NPC(P<0.05).Conclusion:LMP1 and COX-2 may induce expression of VEGF-C directly or LMP1 induce expression of VEGF-C by induce COX-2 expression, may contribute to lymph metastasis and develop NPC.
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To find Epstein-Barr virus (EBV) strains with genetic variations of EBV latent membrane protein 1 (EBV-LMP1) from nasopharyngeal carcinoma (NPC), the full-length DNA of LMP1 genes from 21 NPC biopsies obtained in Hunan province in southern China was amplified and sequenced. Our sequences were compared to those previously reported by the Clustal V method. Results showed that all 21 sequences displayed two amino acid changes most frequently in LMP1 of CD4+ T cell epitopes at codons 144 (F arrow right I, 21/21) and 212 (G arrow right S, 19/21) or (G arrow right N, 2/21). We also show that type A EBV strain is prevalent in the cases of NPC from Hunan province with a 30-bp 18/21 deletion, and we highlight that this deletion resulted in loss of one of the CD4+ T cell-restricted epitopes. The other 3 sequences without this deletion all had a change at codon 344 (G arrow right D). Furthermore, in the major epitope sequence of CD8+ T cells restricted by HLA-A2, all 21 sequences showed changes at codons 126 (L arrow right F) and 129 (M arrow right I). Our study discovered that one of the 21 sequence variations harbored a new change at codon 131 (W arrow right C), and 5/21 specimens showed another novel change at codon 115 (G arrow right A) in the major epitope sequence of CD8+ T cells restricted by HLA-A2. Our study suggests that these sequence variations of NPC-derived LMP1 may lead to a potential escape from host cell immune recognition, protecting latent EBV infection and causing an increase in tumorigenicity.
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Adult , Female , Humans , Male , Middle Aged , Epitopes, T-Lymphocyte/genetics , Genetic Variation , /genetics , Nasopharyngeal Neoplasms/virology , Viral Matrix Proteins/genetics , Amino Acid Sequence , Biopsy , Epitopes, T-Lymphocyte/analysis , Genotype , Polymerase Chain Reaction , Sequence Analysis, DNAABSTRACT
To look for a more stable and convenient way of constructing short hairpin RNA expression vectors targeting the latent membrane protein-1(LMP-1) encoded by Epstein-Barr virus(pshLMP1), and to study the inhibition function of pshLMP1 expression vectors in HNE1 cells, we designed the pshLMP1 expression cassette and pshLMP1 expression vectors by both the annealing method and PCR method and then co-transfected with pEGFP-N1-1158 into HNE1 cells to observe the mRNA and protein levels of LMP-1 genes by green fluorescence analysis, RT-PCR and western blot. pshLMP1 expression vectors were successfully obtained by both methods but better cloning efficiency was achieved and fewer deletions and mutations of nucleotides were achieved with the PCR method. Furthermore, the mRNA and protein levels of LMP-1 genes were down-regulated by pshLMP1 expression vectors. According to our research, we found that the PCR method provides a more efficient way to construct pshLMP1 expression vectors which have the ability to inhibit the function of LMP-1 genes expressed in HNE1 cells, and also provides a novel application of RNA interference technology against-EBV.
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Objective:To investigate the expression of latent membrane protein-1(LMP-1),NET-1,and vascular endothelial growth factor(VEGF)in non-keratin nasopharyngeal carcinoma(NK-NPC)and its clinical significance.Methods :Sixty biopsy specimens from pathologically-confirmed NK-NPC patients,who were treated in the Affilitated Hospital of Nantong University from May 1999 to May 2003,were included in the present study.Using immunohistochemical techniques (Envison two-step),we examined the expression of LMP-1,NET-1 and VEGF protein in the specimens.The relationship between their expression and elnicopathological parameters and the prognosis was anayzed.Ten specimens of chronic nasopharyngitis served as control.Results:(1)The positive rates of LMP-1,NET-1 and VEGF in NK-NPC were significantly higher than those in the chronic nasopharyngitis(P0.05).(3)NET-1 and VEGF expression in NK-NPC specimens were positively correlated with lymph node metastasis and distant metastasis(P
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Interferon regulatory factor 7 (IRF7) is one of the transcriptional factors for the activation of type I Interferon (IFN) genes. It is known that IRF7 and the latent membrane protein 1 (LMP1) of Epstein-Barr virus (EBV) are highly expressed in EBV type III latency cells, and LMP1 induces mRNA expression of IRF7. In this study, the expression pattern of endogenous IRF7 was observed in several B cell lines with or without EBV infection by immunofluorescence staining. IRF7 was localized in the cytoplasm of EBV-negative B cells and EBV type I latency B cell lines. However, IRF7 was located both in the cytoplasm and nucleus of EBV type III latency cell lines. In the Jijoye cell (type III latency cell), IRF7 was colocalized with LMP1 in the cytoplasm in a capping configuration, and their interaction was confirmed by co-immunoprecipitation of LMP1 and IRF7. This colocalization was confirmed by co-transfection of IRF7 and LMP1 plasmids in EBV-negative B cells. These results suggest that the IRF7 and LMP1 interact with each other, and this may relate to the mechanism whereby LMP1 exerts functional effects in B-lymphocytes.
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Humans , Viral Matrix Proteins/biosynthesis , Transcriptional Activation , Signal Transduction , RNA, Messenger/metabolism , Plasmids/metabolism , Microscopy, Fluorescence , Interferon Regulatory Factor-7/biosynthesis , Immunoprecipitation , Herpesvirus 4, Human/metabolism , Gene Expression Regulation , Cytoplasm/metabolism , Cell Line, Tumor , B-Lymphocytes/metabolismABSTRACT
Objective To study the expression and activation of signal transducer and activator of transcription 3(STAT3) in human nasopharyngeal carcinoma (NPC) tissues and its relation with the expression of latent membrane protein 1(LMP1) encoded by Epstein-Barr virus.Methods The expressions of LMP1,STAT3 and phosphated STAT3(p-STAT3) in 45 cases of NPC and 27 cases of chronic nasopharyngitis were studied by immunohistochemical method.Correlation between protein expressions was analyzed.Results The positive rates of LMP1,STAT3 and p-STAT3 in NPC were significantly higher than those in chronic nasopharyngitis(P0.05).Conclusion There are overexpression and abnormal activation of STAT3 protein in NPC tissues.LMP1 may play a role in the activation of STAT3.
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BACKGROUND: Epstein-Barr virus (EBV) is associated with various lymphoproliferative disorders and nasopharyngeal carcinoma. Recently, some gastric cancer cells were observed to contain the EBV sequence. We detected EBV in gastric cancer by using PCR to determine the frequency of EBV-associated gastric cancer, and performed immunohistochemical staining for the latent membrane protein (LMP1), p53 and CD44 to investigate the possible mechanism in EBV-associated gastric cancer. METHODS: Eighty-seven formalin-fixed and paraffin-embedded blocks (40 gastric adenocarcinomas, 34 adjacent normal tissues, 13 metastatic lymph nodes) from 40 surgically resected gastric specimens were studied. All patients were diagnosed with gastric cancer at the Kang-Nam St. Mary's Hospital between April 1995 and April 1997. After DNA was extracted from each paraffin block, we performed PCR and immunohistochemical staining for the LMP1, p53 and CD44. RESULTS: EBV was detected in 4 of 40 cases (10%). In 1 of 4 EBV-positive cases, EBV was also detected in a metastatic lymph node. The immunohistochemical staining for the LMP1, p53 and CD44 were negative in all the EBV-positive cancer patients. Of the patients having these cancers, 2 had a poorly differentiated adenocarcinoma with a lymphoepithelioma-like morphology. DISCUSSION: The frequency of EBV-associated gastric cancer is about 10% in Korea. Considering the negative result of the immunohistochemical staining for the LMP1, p53 and CD44, EBV-associated gastric cancer seems to have a different mechanism of tumorigenesis from ordinary gastric cancer or other EBV-associated cancers. This specific mechanism must be determined by further large scale studies.
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Adult , Female , Humans , Male , Middle Aged , Adenocarcinoma/metabolism , Hyaluronan Receptors/metabolism , Herpesvirus 4, Human/isolation & purification , Immunohistochemistry , Polymerase Chain Reaction , Tumor Suppressor Protein p53/metabolism , Stomach Neoplasms/metabolism , Viral Matrix Proteins/metabolismABSTRACT
Epstein-Barr virus is a kind of herpes virus that has oncogenic potential and is related to the tumorgenesis process of various malignancy. Important advances have been obtained on the study of the structure and functions of Epstein-Barr virus(EBV) latent membrane protein 1(LMP1) and signal transduction pathways mediated by LMP1 in recent years. LMP1 could regulate cellular growth, proliferation, transformation, differentiation, transference and apoptosis by means of signal transduction pathways such as NF-?B, AP-1, JAK/STAT, Ets1, MAPK/ATF2 and cyclin dependent kinase.
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Objective:To detect and analyze the Epstein-Barr virus LMPI gene XhoI-site mutation in plasma of patients with nasopharyngeal carcinoma(NPC)in Chongqing of China.Methods:DNA extraction and PCR amplification was used in plasma of 48 NPC patients and 40 control non-NPC cases from Chongqing of China.All the PCR production was digested by enzyme XhoI,then segregated in 8% PAGE.XhoI-site mutation was analyzed by sequencing and comparing with B95-8 cell.Results: The LMP1 was amplified and digested successfully from 48 of 48 NPC cases(100%)and from 38 of 40 non-NPC cases (95%),but none of LMPI XhoI-site mutation was found.Sequencing was performed on 4 LMPI genes from NPC cases and 5 LMP1 genes from non-NPC cases,they showed the presence of the XhoI-site.Conclusions:XhoI-site in EBV LMP1 gene N terminus has no mutation in plasma of NPC or non-NPC cases in Chongqing of China.The precise relationship of XhoI-site mutation and NPC pathogenesis need further investigation.