Although it is generally believed that, under normal conditions, the only source ofimmunoglobulin is mature B lymphocytes, we recently found several epithelium-derived carcinoma cell lines also express immunolglobulin-like protein. We extended our study to biopsy samples of human cervical tissues with various epithelial lesions. By in situ hybridization, we only detected a low level ofmRNA for the immunoglobulin kappa light chain constant region in epithelia with cervicitis. However, in epithelia with dysplasia and carcinoma, the expression of mRNA for the kappa constant region was markedly increased. There was no significant difference in the level of mRNA for the kappa constant region between epithelial dysplasia and carcinoma. The aberrant expression ofimmunoglobulin kappa light chain constant region in dysplastic and cancerous cervical epithelial cells may serve as a marker for malignant cell transformation.

Aim: To elucidate the interference effect of epigallocatechin-3-gallate (EGCG) on targets of nuclear factor _B (NF-_B) signal transduction pathway activated by EB virus encoded latent membrane protein 1 (LMP1) in nasopharyngeal carcinoma (NPC) cell lines. Methods: The survival rates of CNE1 and CNE-LMP1 cell lines after the EGCG treatment were determined by MTT assay. NF-_B activation in CNE1 and CNE-LMP1 cells after EGCG treatment was analyzed by promoter luciferase reporter system. And then nuclear translocation of NF-_B (p65) after the EGCG treatment was analyzed by immunofluorescence and western blotting. Meanwhile, the changes of I_B_ phosphorylation were observed after the EGCG treatment. EGFR promoter activity was analyzed by promoter luciferase reporter system and EGFR phosphorylation was observed by western blotting after the EGCG treatment. Results: EGCG inhibited the survival rates of CNE1 and CNE-LMP1 cells and NF-_B activation caused by LMP1 in CNE-LMP1 cells. EGCG also suppressed the nuclear translocation of NF-_B (p65) and I_B_ phosphorylation. Meanwhile, EGCG inhibited EGFR promoter activity and EGFR phosphorylation. Conclusions: EGCG inhibited not only the dose-dependent survival rate of NPC cells, but also the dose-dependent activation of NF-_B. This inhibition of LMP1-caused NF-_B activation was mediated via the phosphorylative degradation of its inhibitory protein I_B_, and then EGCG inhibited EGFR activity which was a downstream gene from NF-_B. This study suggests that interference effect of EGCG on targets of signal transduction pathway plays an important role in the anticancer function.

The Epstein-Barr virus (EBV) latent membrane protein 1 (LMP1) oncoprotein may cause multiple cellular changes including the induction of epidermal growth factor receptor (EGFR) expression and activation of the NFnB transcription factor. LMP1 increases the levels of both EGFR protein and mRNA, but does not stabilize EGFR mRNA. Thus, the effects of LMP1 are likely to be mediated by the direct activation of the EGFR promoter. In this study, induction of LMP1 increased the EGFR in both protein and promoter levels in a dosedependent manner using tetracycline-regulated LMP1 expression in nasopharyngeal carcinoma (NPC) cell line. Mutational analysis of the LMP1 protein indicated that the C-terminal activation region-1 (CTAR1) domain was mainly involved in the EGFR promoter induction, while CTAR2 was necessary but not sufficient to induce EGFR promoter. Inhibition of LMP1-mediated NFnB activation by constitutive repressive InBa marginally decreased EGFR promoter activity using transiently transfected InBa dominant negative mutant. Promoter mutagenesis analysis demonstrated that two putative NFnB binding sites of EGFR promoter were very necessary for the transcriptional activity of EGFR induced by LMP1, the proximal NFnB binding site was more important than the distal NFnB binding site, and both NFnB binding sites played a cooperative role. Taken together, Epstein-Barr virus latent membrane protein 1 modulated the EGFR promoter activity in a NFnB-dependent manner.

Epstein-Barr virus (EBV) encoded latent membrane protein 1 (LMP1) is essential for the mmortalization of human B cells and is linked etiologically to several human tumors. LMP1 is an integral membrane protein which acts like a constitutively active receptor. It binds tumor necrosis factor (TNF)-receptor-associated factors (TRAFs), activates NFnB and triggers the transcription factor activating protein-1 (AP-1) via the c-Jun N-terminal kinase (JNK) cascade, but its specific contribution to AP-1 has not been elucidated fully. Members of AP-1 family, the Jun and fos related protein, have been shown to directly interact and form heterodimeric complexes. In this report, using a Tet-on LMP1 HNE2 cell line which is a dual-stable LMP1 integrated nasopharyngeal carcinoma (NPC) cell line and the expression of LMP1 in which could be regulated by Tet-on system, we show that Jun B can efficiently form a new heterodimeric complex with the c-Jun protein under the regulation of LMP1, phosphorylation of c-Jun (ser63, ser73) and Jun B involved in the process of the new heterodimeric form. We also find that this heterodimeric form can bind to the AP-1 consensus sequence. Transfection studies suggest that JNK interaction protein (JIP) could inhibit the heterodimer form of c-Jun and Jun B through blocking the AP-1 signaling pathway triggered by LMP1. The interaction and function between c-Jun protein and Jun B protein increase the repertoire of possible regulatory complexes by LMP1 that could play an important role in the regulation of transcription of specific cellular genes in the process of genesis of nasopharyngeal carcinoma.

and mRNA but does not stabilize EGFR mRNA. Thus the effects of LMP1 are likely to be mediated by direct activation of the EGFR promoter. In this study, induction of LMP1 increased the EGFR in both protein and promoter levels in a dose dependent manner using tetracycline-regulated LMP1 expression in nasopharyngeal carcinoma (NPC) cell line. Mutational analysis of the LMP1 protein indicated that the C-terminal activation region-1 (CTAR1) domain was mainly involved in the EGFR promoter induction, while CTAR2 was necessary but not sufficient to induce EGFR promoter. Inhibition of LMP1 mediated NF_B activation by constitutive repressive inhibitory kappa B alpha (I_B_) marginally decreased EGFR promoter activity using transiently transfected I_B_ dominant negative mutant. Promoter mutagenesis analysis demonstrated that two putative NF_B binding sites of EGFR promoter were very necessary for the transcriptional activity of EGFR induced by LMP1, the proximal NF_B binding site was more important than the distal NF_B binding site. Taken together, Epstein–Barr virus latent membrane protein 1 modulated the EGFR promoter activity in a NF_B dependent manner.