[Effect of Epstein-Barr virus-encoded latent membrane protein 1 on ß-catenin transcriptional activity and expression in nasopharyngeal carcinoma].

OBJECTIVE: To investigate the contribution of latent membrane protein (LMP)1 to nasopharyngeal carcinogenesis via Wnt/ß-catenin signal pathway. METHODS: The recombinant plasmid pHA2-LMP1 was constructed; immunofluorescence staining, Dual-Luciferase Reporter Assay, Western blot and immunohistochemistry staining were used to study the effect of LMP1 on the transcriptional activity and expression of ß-catenin. RESULTS: (1) Abnormal expression of ß-catenin was obtained in 38 cases (50.7%, 38/75), LMP1 expression was obtained in 38 cases (50.7%, 38/75). There was significantly positive correlation between LMP1 expression and abnormal expression of ß-catenin in nasopharyngeal carcinoma tissue (P = 0.008). (2) The expression of ß-catenin in nuclei of NPC cell line CNE1 and CNE2 transfected with pHA2-LMP1 plasmid dramatically increased, and the expression was remarkable in poorly-differentiated NPC cell line CNE2 than that of well-differentiated CNE1 cells. (3) LMP1 expression dramatically increased the transcriptional activity of ß-catenin in CNE1 and CNE2 cells transfected with pHA2-LMP1 and was in a time-dependent. The transcriptional activity of ß-catenin was higher in poorly-defferentiated cell line CNE2 than that of well-differentiated NPC cell line CNE1. (4) LMP1 expression did not affect the total protein expression level of ß-catenin in both CNE1 and CNE2 cell lines. CONCLUSION: EB virus-encoded LMP1 may be involved in the pathogenesis of NPC via ß-catenin signal pathway.

[Correlation of Epstein-Barr virus-encoded latent membrane protein 1 (LMP1) to fascin and phosphorylated Stat3 in nasopharyngeal carcinoma].

BACKGROUND & OBJECTIVE: Latent membrane protein 1 (LMP1) of Epstein-Barr (EB) virus is an important oncogene. Fascin is an actin cross-linking protein involved in cell migration and adhesion. Phosphorylated signal transducer and activator of transcription 3 (pStat3) is a member of STATs family, which is closely related to tumorigenesis. This study was to investigate expressions of LMP1, Fascin and pStat3 in nasopharyngeal carcinoma (NPC) tissues and lymph node metastases of NPC, thus to explore their correlations to the initiation and progression of NPC. METHODS: Expressions of EBV-encoded small RNA (EBER), LMP1, Fascin, pStat3, p53, Ki-67 and Bcl-2 were detected in 43 NPC tissues (21 with and 22 without lymph node metastases) and 21 corresponding lymph node metastases using in situ hybridization or immunohistochemistry (IHC). Data were statistically analyzed. Expressions of pStat3 and Fascin were measured in the NPC cell line CNE1 transfected with LMP1-expressing plasmid using Western blot. RESULTS: Positive EBER expression was detected in all 43 NPC tissues and 21 lymph node metastases in NPC. The expression rates of LMP1, Fascin, pStat3, p53, Ki-67, and Bcl-2 were 69.8% (30/43), 93.0% (40/43), 72.1% (31/43), 90.7% (39/43), 88.4% (38/43) and 88.4% (38/43)in 43 NPC tissues, respectively. LMP1 expression was positively correlated with the expression level of Fascin, pStat3, p53, Ki-67 and Bcl-2 in 43 NPC cases(P < 0.05). LMP1 was found in 10 out of 21 (46.7%) lymph node metastases in NPC. In addition, LMP1 expression dramatically increased pStat3 and Fascin in CNE1 cells. CONCLUSIONS: LMP1 is expressed in lymph node metastatases in NPC. The expression of LMP1 is positively correlated with Fascin, pStat3 and the proliferation index of tumor cells. Moreover, LMP1 up-regulates pStat3 and Fascin in NPC cells.

[Analysis of Epstein-Barr virus BamH I "f" variant in nodal metastasis of nasopharyngeal carcinoma].

OBJECTIVE: To investigate the Epstein-Barr virus (EBV) BamH I "f" variant in primary nasopharyngeal carcinoma (NPC) and its metastases in lymph nodes (LN). METHODS: In situ hybridization was used to detect EBV-encoded small RNA (EBER) expression in 21 paired paraffin-embedded tissue from primary NPC and their lymph node metastases and 22 primary NPC without lymph node metastasis. PCR and restriction fragment length polymorphism (RFLP) assay were used to detect EBV BamH I "f" variant in all cases of NPCs, lymph node metastases and 50 cases of chronic inflammation of nasopharynx from Canton. RESULTS: All cases of NPCs and their lymph node metastases showed EBER expression, indicating a high EBV-positive rate in Cantonese NPC patients. EBV BamH I "f" variant was found in 11 cases (52.4%, 11/21) of primary NPCs with LN metastasis, 12 cases (57.1%, 12/21) of the LN metastases, and 18 cases (81.8%, 18/22) of primary NPCs without LN metastasis. However, of the 50 cases of chronic inflammation of nasopharynx, only one case (2.1%, 1/47) demonstrated BamH I "f" variant. The frequency of BamH I "f" variant in NPC was therefore dramatically higher than that in chronic inflammation of nasopharynx. It is of note that atypical hyperplasia was observed in a few epithelial cells from the case of chronic inflammation of nasopharynx expressing BamH I "f" variant. CONCLUSIONS: The frequency of EBV BamH I "f" variant in NPC is significantly higher than that in chronic inflammation of nasopharynx. It is the first demonstration that the BamH I "f" variant is also present in the LN metastases of NPC. The frequency of BamH I "f" variant in metastatic NPC of the lymph node is almost equal to that of primary NPCs.