CpG methylation of the major Epstein-Barr virus latency promoter in Burkitt's lymphoma and Hodgkin's disease

Abstract

The Epstein-Barr virus (EBV) latency C promoter drives expression of a family of viral proteins commonly targeted by CD8 cytotoxic T cells. These proteins are not generally expressed in African Burkitt's lymphoma and in EBV-associated Hodgkin's disease. The failure to express these proteins is almost certainly an important factor in the evasion of immunosurveillance by EBV-associated tumors. In a previous study, we have shown that transcriptional activation of the C promoter is inhibited by methylation of a particular CpG site upstream of the promoter that prevents binding of a cellular protein (CBF2), and we have shown that this and adjacent CpG sites are methylated in a Burkitt's lymphoma cell line. In the present study, we show that CpG sites in the CBF2 binding region are predominantly methylated in African Burkitt's lymphoma and in EBV-associated Hodgkin's disease. In addition, we present the first direct evidence that the C promoter is transcriptionally silent in Burkitt's lymphoma. In contrast, we show a complete absence of methylation in the CBF2 binding region in a case of reversible EBV-associated B-cell lymphoma arising in an immunocompromised patient whose tumor shows C promoter transcriptional activity. By inhibiting expression of highly antigenic viral proteins, methylation of transcriptional control sequences may veil the presence of virus in tumor tissue from CD8(+) cytotoxic T-cell immune surveillance and thus facilitate viral tumorigenesis.

High‐density methylation of p14ARF and p16INK4A in Epstein‐Barr virus–associated gastric carcinoma

“…One of the important functions of DNA methylation is genome defense against foreign invaders in mammalian cells 18, 19. EBV infection may induce Dnmt3a/3b‐independent methylation in infected cells, which would primarily methylate the viral promoter genes and suppress the viral latent genes 20, 21. Further studies are necessary to clarify the mechanisms of hypermethylation in EBVaGC, including the putative role of EBV gene products.…”

Latency pattern of Epstein‐Barr virus and methylation status in Epstein‐Barr virus‐associated hemophagocytic syndrome

“…Methylation-associated transcriptional repression is also recognized in viral DNA, including DNA of EBV, Marek disease virus [Hayashi et al, 1994] and simian foamy virus type 3 [Schweizer et al, 1993], and may play a role in normal differentiation and tumorigenesis [Nonkwelo and Long, 1993;Tao et al, 1998b]. An inverse relationship between methylation and transcriptional activity has been demonstrated for several EBV promoters (Wp [Bell et al, 1998;Kirby et al, 2000;Tierney et al, 2000a,b], Cp [Robertson et al, 1995[Robertson et al, , 1996Robertson and Ambinder, 1997a,b;Salamon et al, 2001] and promoters for LMP1 [Falk et al, 1998] and BHRF1 [Nonkwelo and Long, 1993]).…”

“…Except for one clone from pt 3 (clone 16), it was apparent that the Cp region in EBV-associated hemophagocytic syndrome was hyper-methylated, regardless of disease stage or patient. Several mechanisms that regulate Cp activity have been described [Robertson et al, 1995[Robertson et al, , 1996Robertson and Ambinder, 1997a,b;Salamon et al, 2001]. Activity of Cp is autoregulated by both EBNA1 and EBNA2.…”

“…EBNA2 transcribed from Wp upregulates Cp, drives expression of the EBNA family of nuclear proteins in latency III, and also contributes to the positive regulation of the LMP2A, LMP2B, and LMP1 promoters. Cp can also be regulated by the binding of two cellular factors, CBF2 and EBNA2-interacting protein RBP-Jk/CBF1 [Robertson et al, 1995[Robertson et al, , 1996Robertson and Ambinder, 1997a,b;Fuentes-Panana and Ling, 1998;Zhou et al, 2000;Salamon et al, 2001]. The binding activity of CBF2 to EBNA2 is inhibited by CpG methylation, but the binding activity of CBF1 is not inhibited [Robertson et al, 1995].…”

“…Levels of methylation are generally related inversely to levels of transcriptional activity. Methylation is also important in the gene regulation of EBV by using the host-cell methylation system [Robertson et al, 1995[Robertson et al, , 1996Robertson and Ambinder, 1997a,b;Schaefer et al, 1997;Paulson and Speck, 1999;Tierney et al, 2000a;Salamon et al, 2001]. Tierney et al [2000a] reported that Wp was hypermethylated and that Cp was completely unmethylated in most patients with infectious mononucleosis.…”