Epstein-Barr Virus Latent Membrane Protein 1 Induces Cancer Stem/Progenitor-Like Cells in Nasopharyngeal Epithelial Cell Lines

Recent studies suggest the existence of cancer stem cells (CSC) and cancer progenitor cells (CPC), although strict definitions of neither CSC nor CPC have been developed. We have produced evidence that the principal oncoprotein of Epstein-Barr virus (EBV), latent membrane protein 1 (LMP1), which is associated with human malignancies, especially nasopharyngeal carcinoma (NPC), promotes tumor cell invasion and metastasis, as well as the epithelial-mesenchymal transition (EMT). However, whether LMP1 is involved in the development of CSC/CPC is still unclear. This study investigates whether the expression of EBV-LMP1 is related to the development of CSC/CPC. Analysis of cancer stem cell markers reveals that LMP1 induces the CD44high CD24low CSC/CPC-like phenotype as well as self-renewal abilities in LMP1-expressing epithelial cell lines. In addition, we show here that LMP1 induction in epithelial cells causes high tumorigenicity and rapid cellular proliferation. Furthermore, we found that LMP1 expression increased the expression of several CPC markers as well as producing increased levels of EMT markers. Our findings indicate that LMP1 can induce a CPC-like rather than a CSC-like phenotype in epithelial cells and suggest that LMP1-induced phenotypic changes contribute to the development of NPC

MUC1 Induced by Epstein-Barr Virus Latent Membrane Protein 1 Causes Dissociation of the Cell-Matrix Interaction and Cellular Invasiveness via STAT Signaling

Disruption of cellular adhesion is an essential pathobiologic step leading to tumor dissemination. Mucin 1 (MUC1) is a mucinous glycoprotein expressed at the surfaces of epithelial cells in many tissues and their carcinomas. MUC1 plays crucial roles in tumor invasion and metastasis, especially in opposing cell adhesion. We have shown that virus infection, specifically by the human tumor virus Epstein-Barr virus (EBV) induces a spectrum of cellular invasiveness and metastasis factors. Here we show that expression of MUC1 is increased in diverse latently EBV-infected cell lines that express latent membrane protein 1 (LMP1), the main viral oncoprotein, and that the level of MUC1 was suppressed by expression of a dominant-negative mutant of LMP1. Expression of LMP1 in EBV-negative nasopharyngeal cell lines induces expression of MUC1 through activation of the MUC1 promoter via binding of STAT1 and STAT3. Finally, LMP1 reduces cell adhesion ability, which is restored by inhibition of MUC1 expression with MUC1 small interfering RNA (siRNA). In addition, LMP1 increases cell invasiveness, which is suppressed by MUC1 siRNA. Thus, LMP1 induces MUC1, a factor important in an early step of detachment and release of tumor cells, which along with induction of other invasiveness and angiogenic factors may combine to act in a complex sequential process that culminates in metastasis of EBV-infected tumor cells

LINE-1 hypomethylation status of circulating cell-free DNA in plasma as a biomarker for colorectal cancer.

Colorectal cancer (CRC) is a serious public health problem and non-invasive biomarkers improving diagnosis or therapy are strongly required. Circulating cell-free DNA (cfDNA) has been a promising target for this purpose. In this study, we evaluated the potential of long interspersed nuclear element-1 (LINE-1) hypomethylation as a blood biomarker for CRC. LINE-1 hypomethylation level in plasma cfDNA in 114 CRC patients was retrospectively examined by absolute quantitative analysis of methylated alleles real-time PCR, and was expressed using LINE-1 hypomethylation index (LHI) [unmethylated copy number/ (methylated copy number + unmethylated copy number)]. Greater LHI values indicated enhanced hypomethylation. In our clinicopathological analysis, CRC patients with large tumors (≥6.0 cm), advanced N stage (≥2), and distant metastasis (M1) had statistically significantly higher cfDNA LHI than other CRC patients, suggesting cfDNA LHI as a disease progression biomarker for CRC. Furthermore, early stage I/II (n = 57) as well as advanced stage III/IV (n =57) CRC patients had significantly higher cfDNA LHI than healthy donors (n=53) [stage I/II: median 0.369 (95% confidence interval, 0.360-0.380) vs. 0.332 (0.325-0.339), P \u3c 0.0001; stage III/IV: 0.372 (0.365-0.388) vs. 0.332 (0.325-0.339), P \u3c 0.0001]. The receiver operating characteristic analysis showed that cfDNA LHI had the detection capacity of CRC with area under the curve(AUC) of 0.79 and 0.83 in stage I/II and stage III/IV CRC patients, respectively. The present study demonstrated for the first time the potential of plasma cfDNA LHI as a novel biomarker for CRC, particularly for early stage detection

Epstein-Barr Virus latent membrane protein 1 induces Snail and epithelial–mesenchymal transition in metastatic nasopharyngeal carcinoma

Background:Epstein-Barr Virus (EBV)-associated nasopharyngeal carcinoma (NPC) is distinctive among head-and-neck cancers in its undifferentiated histopathology and highly metastatic character. We have recently investigated the involvement of epithelial–mesenchymal transition (EMT) in NPC. In a previous study, we found a close association of expression of LMP1, the principal EBV oncoprotein, with expression of Twist and induction of EMT.Methods:We analysed expression of Snail in 41 NPC tissues by immunohistochemistry. The role of Twist as well as Snail in EMT of NPC was investigated by using NP69SV40T human nasopharyngeal cells.Results:In NPC tissues, overexpression of Snail is associated with expression of LMP1 in carcinomatous cells. In addition, expression of Snail positively correlated with metastasis and independently correlated inversely with expression of E-cadherin. Expression of Twist had no association with expression of E-cadherin. Further, in a human nasopharyngeal cell line, LMP1 induces EMT and its associated cellular motility and invasiveness. Expression of Snail is induced by LMP1 in these cells, and small hairpin RNA (shRNA) to Snail reversed the cellular changes. By contrast, Twist did not produce EMT in these nasopharyngeal cells.Conclusions:This study strengthens the association of EMT with the metastatic behaviour of NPC. These results suggest that induction of Snail by the EBV oncoprotein LMP1 has a pivotal role in EMT in NPC

Epstein-Barr virus infection and chronic lymphocytic leukemia: a possible progression factor?

Epstein-Barr virus is pathogenically associated with a well defined group of lymphoid and epithelial tumors in which the virus directly drives transformation of infected cells. Recent evidence however indicates that this virus may infect a subpopulation of tumor cells in patients with chronic lymphocytic leukemia (CLL) and EBV infection has been also associated with Richter transformation in a fraction of cases. We herein review available data suggesting a possible role of EBV as a direct or micro-environmental progression factor in a subset of CLL