Lee Fah Yap

Expression of the Epstein-Barr Virus-Encoded Epstein-Barr Virus Nuclear Antigen 1 in Hodgkin's Lymphoma Cells Mediates Up-Regulation of CCL20 and the Migration of Regulatory T Cells

In approximately 50% of patients with Hodgkins lymphoma (HL), the Epstein-Barr virus (EBV), an oncogenic herpesvirus, is present in tumor cells. After microarray profiling of both HL tumors and cell lines, we found that EBV infection increased the expression of the chemokine CCL20 in both primary Hodgkin and Reed-Sternberg cells and Hodgkin and Reed-Sternberg cell-derived cell lines. Additionally, this up-regulation could be mediated by the EBV nuclear antigen 1 protein. The higher levels of CCL20 in the supernatants of EBV-infected HL cell lines increased the migration of CD4(+) lymphocytes that expressed FOXP3, a marker of regulatory T cells (Tregs), which are specialized CD4(+) T cells that inhibit effector CD4(+) and CD8(+) T cells. In HL, an increased number of Tregs is associated with the loss of EBV-specific immunity. Our results identify a mechanism by which EBV can recruit Tregs to the microenvironment of HL by inducing the expression of CCL20 and, by doing so, prevent immune responses against the virus-infected tumor population. Further investigation of how EBV recruits and modifies Tregs will contribute not only to our understanding of the pathogenesis of virus-associated tumors but also to the development of therapeutic strategies designed to manipulate Treg activity.

Epstein-Barr virus: more than 50 years old and still providing surprises

It is more than 50 years since the Epstein–Barr virus (EBV), the first human tumour virus, was discovered. EBV has subsequently been found to be associated with a diverse range of tumours of both lymphoid and epithelial origin. Progress in the molecular analysis of EBV has revealed fundamental mechanisms of more general relevance to the oncogenic process. This Timeline article highlights key milestones in the 50-year history of EBV and discusses how this virus provides a paradigm for exploiting insights at the molecular level in the diagnosis, treatment and prevention of cancer.

The Epstein–Barr virus and the pathogenesis of lymphoma

Since the discovery in 1964 of the Epstein–Barr virus (EBV) in African Burkitt lymphoma, this virus has been associated with a remarkably diverse range of cancer types. Because EBV persists in the B cells of the asymptomatic host, it can easily be envisaged how it contributes to the development of B‐cell lymphomas. However, EBV is also found in other cancers, including T‐cell/natural killer cell lymphomas and several epithelial malignancies. Explaining the aetiological role of EBV is challenging, partly because the virus probably contributes differently to each tumour and partly because the available disease models cannot adequately recapitulate the subtle variations in the virus–host balance that exist between the different EBV‐associated cancers. A further challenge is to identify the co‐factors involved; because most persistently infected individuals will never develop an EBV‐associated cancer, the virus cannot be working alone. This article will review what is known about the contribution of EBV to lymphoma development. Copyright

A genome-wide association study identifies ITGA9 conferring risk of nasopharyngeal carcinoma

To identify a gene(s) susceptible to nasopharyngeal carcinoma (NPC), we carried out a genome-wide association study (GWAS) through genotyping of more than 500 000 tag single-nucleotide polymorphisms (SNPs), using an initial sample set of 111 unrelated NPC patients and 260 controls of a Malaysian Chinese population. We further evaluated the top 200 SNPs showing the smallest P-values, using a replication sample set that consisted of 168 cases and 252 controls. The combined analysis of the two sets of samples found an SNP in intron 3 of the ITGA9 (integrin-α 9) gene, rs2212020, to be strongly associated with NPC (P=8.27 × 10−7, odds ratio (OR)=2.24, 95% confidence intervals (CI)=1.59–3.15). The gene is located at 3p21 which is commonly deleted in NPC cells. We subsequently genotyped additional 19 tag SNPs within a 40-kb linkage disequilibrium (LD) block surrounding this landmark SNP. Among them, SNP rs189897 showed the strongest association with a P-value of 6.85 × 10−8 (OR=3.18, 95% CI=1.94–5.21), suggesting that a genetic variation(s) in ITGA9 may influence susceptibility to NPC in the Malaysian Chinese population.

Upregulation of Eps8 in oral squamous cell carcinoma promotes cell migration and invasion through integrin-dependent Rac1 activation

Oral squamous cell carcinoma (OSCC) is a lethal disease and early death usually occurs as a result of local invasion and regional lymph node metastases. Current treatment regimens are, to a certain degree, inadequate, with a 5-year mortality rate of around 50% and novel therapeutic targets are urgently required. Using expression microarrays, we identified the eps8 gene as being overexpressed in OSCC cell lines relative to normal oral keratinocytes, and confirmed these findings using RT–PCR and western blotting. In human tissues, we found that Eps8 was upregulated in OSCC (32% of primary tumors) compared with normal oral mucosa, and that expression correlated significantly with lymph node metastasis (P=0.032), suggesting a disease-promoting effect. Using OSCC cell lines, we assessed the functional role of Eps8 in tumor cells. Although suppression of Eps8 produced no effect on cell proliferation, both cell spreading and migration were markedly inhibited. The latter cell functions may be modulated through the small GTP-ase, Rac1 and we used pull-down assays to investigate the role of Eps8 in Rac1 signaling. We found that αvβ6- and α5β1-integrin-dependent activation of Rac1 was mediated through Eps8. Knockdown of either Eps8 or Rac1, inhibited integrin-dependent cell migration similarly and transient expression of constitutively active Rac1 restored migration of cells in which Eps8 expression had been suppressed. We also showed that knockdown of Eps8 inhibited tumor cell invasion in an organotypic model of OSCC. These data suggest that Eps8 and Rac1 are part of an integrated signaling pathway modulating integrin-dependent tumour cell motility and identify Eps8 as a possible therapeutic target.

The ATM tumour suppressor gene is down-regulated in EBV-associated nasopharyngeal carcinoma

A micro‐array analysis using biopsies from patients with EBV‐positive undifferentiated nasopharyngeal carcinoma (NPC) and from cancer‐free controls revealed down‐regulation of tumour suppressor genes (TSG) not previously associated with this disease; one such gene was the ataxia telangiectasia mutated (ATM) gene. Q‐PCR confirmed down‐regulation of ATM mRNA and ATM protein expression in tumour cells was weak or absent in almost all cases. In NPC cell lines, however, ATM was down‐regulated only in the EBV‐positive line, C666.1, and in none of five EBV‐negative lines. In vitro infection of EBV‐negative NPC cell lines with a recombinant EBV was followed by the down‐regulation of ATM mRNA and protein, and only EBV‐positive cells showed a defective DNA damage response following γ‐irradiation. Our data suggest that loss of ATM function could be an important step in the pathogenesis of NPC, and may have implications for the treatment of this disease. Copyright

The opposing roles of NOTCH signalling in head and neck cancer: a mini review

NOTCH signalling can exert oncogenic or tumour suppressive effects in both solid and haematological malignancies. Similar to T-cell acute lymphoblastic leukaemia (T-ALL), early studies suggested a pro-tumorigenic role of NOTCH in head and neck squamous cell carcinoma (HNSCC), mainly based on the increased expression levels of the genes within the pathway. Recently, data from exome sequencing analyses unexpectedly pointed to a tumour suppressor role for NOTCH in HNSCC by identifying loss-of-function mutations in the NOTCH1 gene in a significant proportion of patients. These data have questioned the accepted role of NOTCH in HNSCC and the possible rationale of targeting NOTCH in this disease. This review summarises the current information on NOTCH signalling in HNSCC and discusses how this pathway can apparently exert opposing effects within the same disease.

Mechanism for phenol tolerance in phenol-degrading Comamonas testosteroni strain

Comamonas testosteroni P15 and its mutant strain E23 can tolerate and utilize phenol as the sole source of carbon and energy at up to 15 mM and 20 mM, respectively. Compared to the wild type P15, mutant E23 showed higher values of Ks and Ki but a lower μmax value, and had lower phenol hydroxylase and catechol 2,3-dioxygenase activities. Without phenol exposure, mutant E23 demonstrated a two-fold greater amount of cardiolipin than the wild type P15. Upon exposure to phenol, an increase in cardiolipin at the expense of phosphatidylethanolamine was observed in the wild type P15. However, there was no significant difference in major phospholipid contents between mutant E23 cells grown in the presence or absence of phenol. It was noted that the ratio of trans/cis fatty acids of phosphatidylethanolamine and cardiolipin in mutant E23 was 65–70% higher than that in the wild type P15. In the absence of phenol, the degree of saturation of cardiolipin in mutant E23 was 33% higher than that in wild type P15. In contrast to earlier findings, an increase in C16:1 9trans with a simultaneous decrease in C18:1 11cis instead of C16:1 9cis was observed in specific classes of phospholipids.

The antineoplastic properties of FTY720: Evidence for the repurposing of fingolimod

Almost all drugs approved for use in humans possess potentially beneficial ‘off‐target’ effects in addition to their principal activity. In some cases this has allowed for the relatively rapid repurposing of drugs for other indications. In this review we focus on the potential for re‐purposing FTY720 (also known as fingolimod, Gilenya™), an immunomodulatory drug recently approved for the treatment of multiple sclerosis (MS). The therapeutic benefit of FTY720 in MS is largely attributed to the immunosuppressive effects that result from its modulation of sphingosine 1‐phosphate receptor signalling. However, this drug has also been shown to inhibit other cancer‐associated signal transduction pathways in part because of its structural similarity to sphingosine, and consequently shows efficacy as an anti‐cancer agent both in vitro and in vivo. Here, we review the effects of FTY720 on signal transduction pathways and cancer‐related cellular processes, and discuss its potential use as an anti‐cancer drug.

Detection and Screening of Salmonella enteritidis- Infected Chickens with Recombinant Flagellin

Screening and identification of Salmonella enteritidis in commercial poultry flocks have assumed principal roles in preventing transmission of this pathogen to humans from hen eggs. Serologic diagnosis of S. enteritidis infection in commercial flocks currently relies on laboratory-based tests for detection of antibodies to the lipopolysaccharide, whole flagella, and bacteria. We amplified a sequence from the g,m flagellin of S. enteritidis, followed by cloning, expression, and purification of the protein. The recombinant protein was first characterized by western blot and subsequently evaluated as enzyme-linked immunosorbent assay (ELISA) antigen for detection of S. enteritidis infection. A total number of 49 positive sera and 40 negative sera were tested for ELISA validation. A cutoff value of 0.14 was shown to be sufficient to discriminate the negative and positive sera. Results obtained by testing sera raised against different bacterial strains/serotypes further confirmed that this recombinant flagellin-based ELISA was indeed specific for the detection of S. enteritidis. Both sensitivity and specificity of the developed ELISA test were comparable with a commercially available test, indicating that it is a highly promising and reliable diagnostic tool for S. enteritidis infection.