EBV–encoded miRNAs can sensitize nasopharyngeal carcinoma to chemotherapeutic drugs by targeting BRCA1

Nasopharyngeal carcinoma (NPC) is an Epstein‐Barr virus (EBV)‐associated epithelial malignancy. The high expression of BART‐miRNAs (miR‐BARTs) during latent EBV infection in NPC strongly supports their pathological importance in cancer progression. Recently, we found that several BART‐miRNAs work co‐operatively to modulate the DNA damage response (DDR) by reducing Ataxia‐telangiectasia‐mutated (ATM) activity. In this study, we further investigated the role of miR‐BARTs on DDR. The immunohistochemical study showed that the DNA repair gene, BRCA1, is consistently down‐regulated in primary NPCs. Using computer prediction programs and a series of reporter assays, we subsequently identified the negative regulatory role of BART2‐3p, BART12, BART17‐5p and BART19‐3p in BRCA1 expression. The ectopic expression of these four miR‐BARTs suppressed endogenous BRCA1 expression in EBV‐negative epithelial cell lines, whereas BRCA1 expression was enhanced by repressing endogenous miR‐BARTs activities in C666‐1 cells. More importantly, suppressing BRCA1 expression in nasopharyngeal epithelial cell lines using miR‐BART17‐5p and miR‐BART19‐3p mimics reduced the DNA repair capability and increased the cell sensitivity to the DNA‐damaging chemotherapeutic drugs, cisplatin and doxorubicin. Our findings suggest that miR‐BARTs play a novel role in DDR and may facilitate the development of effective NPC therapies.     

T cell lymphoproliferative disorders associated with anti-tumor necrosis factor alpha antibody therapy for ulcerative colitis: literature summary

The enhanced risk of development of lymphoproliferative disorders in patients with inflammatory bowel disease has been attributed to immunosuppressive/immunomodulatory therapies. Infliximab is a chimeric monoclonal immunoglobulin G1 antibody directed against tumor necrosis factor alpha (TNF-α) that was approved by the Food and Drug Administration (FDA) in 1998 as an effective therapeutic agent against inflammatory bowel disease. Malignant lymphomas of both B and T cell lineage have been described in patients undergoing therapy involving TNF-α blockade. To date, eight cases of Epstein–Barr virus (EBV)-negative hepatosplenic T cell lymphoma associated with infliximab have been reported to the FDA’s Adverse Event Reporting System, as well as several other T cell lymphoproliferative disorders with aggressive clinical outcomes. We present the histologic, immunophenotypic, and molecular features of a T cell lymphoproliferative disorder involving the axillary lymph node of a 33-year-old male following infliximab treatment for ulcerative colitis. These EBV-negative lymphomas suggest that lymphoproliferative disorders following infliximab treatment for inflammatory bowel disease may involve EBV-independent immune dysregulation. The spectrum of lymphoproliferative disorders associated with infliximab and the potential mechanisms by which they occur are discussed.     

A mutation in Epstein-Barr virus LMP2A reveals a role for phospholipase D in B-Cell antigen receptor trafficking

Epstein-Barr virus (EBV) latent infection of B cells blocks the interrelated signaling and antigen-trafficking functions of the BCR through the activity of its latent membrane protein 2A (LMP2A). At present, the molecular mechanisms by which LMP2A exerts its control of BCR functions are only poorly understood. Earlier studies showed that in B cells expressing LMP2A containing a tyrosine mutation at position 112 in its cytoplasmic domain (Y112-LMP2A), the BCR could initiate signaling but could not properly traffic antigen for processing. Here, we show that BCR signaling in Y112-LMP2A-expressing cells is attenuated with a reduction in both the degree and duration of phosphorylation of key components of the BCR signaling cascade including Syk, BLNK, PI3K, and Btk. Notably, Y112-LMP2A expression completely blocked the BCR-induced activation of phospholipase D (PLD), a lipase implicated in the intracellular trafficking of a variety of surface receptors. We show that blocking PLD activity, by expressing Y112-LMP2A, treating cells with the PLD inhibitor 1-butanol or reducing PLD expression by siRNA, blocked BCR trafficking to class II-containing compartments. Moreover, Y112-LMP2A expression blocked the recruitment of phosphorylated forms of the downstream BCR signaling components, Erk and JNK, through both PLD-dependent and PLD-independent mechanisms. Thus, the investigation of the mechanism by which Y112-LMP2A blocks BCR function revealed an essential role for PLD in BCR trafficking for antigen processing.     

Cytolytic CD4 cells: Direct mediators in infectious disease and malignancy

CD4 T cells have traditionally been regarded as helpers and regulators of adaptive immune responses; however, a novel role for CD4 T cells as direct mediators of protection against viral infections has emerged. CD4 T cells with cytolytic potential have been described for almost 40 years, but their role in host protection against infectious disease is only beginning to be realized. In this review, we describe the current literature identifying these cells in patients with various infections, mouse models of viral infection and our own work investigating the development of cytolytic CD4 cells in vivo and in vitro. CD4 CTL are no longer considered an artefact of cell culture and may play a physiological role in viral infections such as EBV, CMV, HIV and influenza. Therefore, vaccine strategies aimed at targeting CD4 CTL should be developed in conjunction with vaccines incorporating B cell and CD8 CTL epitopes.     

NF-kappaB inhibitors induce lytic cytotoxicity in Epstein-Barr virus-positive nasopharyngeal carcinoma cells

Epstein-Barr virus (EBV) infection in tumor cells is generally restricted to the latent forms of viral infection. Switching the latent form of viral infection into the lytic form may induce tumor cell death. An important nuclear factor, nuclear factor (NF)-kappaB, is thought to play an essential role in EBV lytic infection; high levels of NF-kappaB can inhibit EBV lytic replication. In this study, we tested the effect of inducing EBV lytic replication using two NF-kappaB inhibitors: Bay11-7082 and Z-LLF-CHO, to reveal the possibility of targeting EBV-positive cancer therapy with these two NF-kappaB inhibitors. Our results showed that Bay11-7082 and Z-LLF-CHO reactivated EBV in a dose-dependent manner, thus resulting in EBV-positive 5-8F cell death. In contrast, there was no significant effect on EBV-negative HNE3 cells. When ganciclovir was used in combination with either Bay11-7082 or Z-LLF-CHO to treat 5-8F cells, the cytotoxic effect of the NF-kappaB inhibitor was amplified. The finding indicates that inhibiting the NF-kappaB activity of EBV-positive cells can induce lytic replication of EBV and cause lytic cytotoxicity against these cells.     

Induction of apoptosis in Epstein-Barr virus-infected B-lymphocytes by the NF-kappaB inhibitor DHMEQ

Epstein-Barr virus (EBV) causes EBV-associated lymphoproliferative diseases in patients with profound immune suppression. Most of these diseases are life-threatening and the prognosis of AIDS-associated lymphomas is extremely unfavorable. Polyclonal expansion of virus infected B-cell predisposes them to transformation. We investigated the possibility of nuclear factor kappa B (NF-kappaB) inhibition by dehydroxymethylepoxyquinomicin (DHMEQ) for the treatment and prevention of EBV-associated lymphoproliferative diseases. We examined the effect of DHMEQ on apoptosis induction in four EBV-transformed lymphoblastoid cell lines as well as peripheral blood mononuclear cells infected with EBV under immunosuppressed condition. DHMEQ inhibits NF-kappaB activation in EBV-transformed lymphoblastoid cell lines and induces apoptosis by activation of mitochondrial and membranous pathways. Using an in vivo NOD/SCIDgammac mouse model, we showed that DHMEQ has a potent inhibitory effect on the growth of lymphoblastoid cells. In addition, DHMEQ selectively purges EBV-infected cells expressing latent membrane protein (LMP) 1 from peripheral blood mononuclear cells and inhibits the outgrowth of lymphoblastoid cells. These results suggest that NF-kappaB is a molecular target for the treatment and prevention of EBV-associated lymphoproliferative diseases. As a potent NF-kappaB inhibitor, DHMEQ is a potential compound for applying this strategy in clinical medicine.     

Epstein-Barr病毒胸苷激酶在大肠杆菌表达的研究

研究重组EB病毒胸苷激酶(thymidine kinase of     

应用H.E染色的鼻咽癌细胞涂片进行DNA含量测定和EB病毒基因原位杂交的研究

分析鼻咽癌常规 H.E染色细胞涂片分别作 Feulgen染色检测 DNA含量和原位杂交检测 EB病毒编码 RNAs(EBERs)的效果 ;将常规 HE染色的 9例正常鼻咽细胞涂片和 38例鼻咽癌细胞涂片用 1%酸性酒精褪色 ,然后作 Feulgen染色 ,应用图象分析仪测定涂片细胞 DNA含量 ,并将 38例鼻咽癌细胞病例的阳性涂片进行 EBERs原位杂交检测 ;结果显示正常鼻咽细胞均为 DNA二倍体核型 ,38例癌阳性涂片中呈 DNA二倍体者 6例 ,DNA非二倍体者 32例 (84.2 % ) ,癌细胞核 EBERs阳性者 35例 (92 .1% ) ;结果表明 HE染色的鼻咽癌细胞学涂片经褪色后作 Feulgen染色和原位杂交检测 ,能较满意进行 DNA和 EBERs分析 ,表明常规 H.E染色和褪色处理均不影响 Feulgen染色和 EB病毒原位杂交的质量效果。本检测方法可靠、可行 ,适用于常规染色细胞学样本的回顾性研究和随访研究 ,并可用于鼻咽癌可疑病人的诊断和鉴别诊断