Cecad

Recent studies impressively showed the diagnostic potential of seroreactivity patterns for different tumor types, offering the prospect for low-cost screening of numerous tumor types simultaneously. One of the major challenges toward this goal is to prove that seroreactivity profiles do not only allow for identifying a tumor but also allow for distinguishing tumors from other pathologies of the same organ. We chose glioma as a model system and tested 325 sera (88 glioma, 95 intracranial tumors, 60 other brain pathologies, and 82 healthy controls) for seroreactivity on a panel of 35 antigens. We were able to discriminate between glioma and all other sera with cross-validated specificity of 86.1%, sensitivity of 85.2%, and accuracy of 85.8%. We obtained comparably good results for the separation of glioma versus nontumor brain pathologies and glioma versus other intracranial tumors. Our study provides first evidence that seroreactivity patterns allow for an accurate discrimination between a tumor and pathologies of the same organ even between different tumor types of the same organ.

Resistance toward apoptotic stimuli mediated by overexpression of antiapoptotic factors or extracellular survival signals is considered to be responsible for accumulation of malignant B cells in chronic lymphocytic leukemia (CLL). TOSO was identified as overexpressed candidate gene in CLL, applying unit-transformation assays of publicly available microarray datasets. Based on CLL samples from 106 patients, TOSO was identified to exhibit elevated relative expression (RE) of 6.8 compared with healthy donor B cells using quantitative real-time polymerase chain reaction (PCR; P = .004). High levels of TOSO expression in CLL correlated with high leukocyte count, advanced Binet stage, previous need for chemotherapy, and unmutated IgV(H) status. CD38(+) CLL subsets harboring proliferative activity showed enhanced TOSO expression. We evaluated functional mechanisms of aberrant TOSO expression and identified TOSO expression significantly induced by B-cell receptor (BCR) stimulation compared with control cells (RE; 8.25 vs 4.86; P = .01). In contrast, CD40L signaling significantly reduced TOSO expression (RE, 2.60; P = .01). In summary, we show that the antiapoptotic factor TOSO is associated with progressive disease and enhanced in the proliferative CD38(+) CLL subset. Both association with unmutated IgV(H) and the specific induction of TOSO via the BCR suggest autoreactive BCR signaling as a key mediator of apoptosis resistance in CLL.

A variety of genetic and epigenetic abnormalities were characterized over the last years in Hodgkin and Reed-Sternberg (H-RS) cells of classic Hodgkin Lymphoma (cHL). It was speculated that simultaneous inhibition of multiple signalling pathways might be a promising strategy to target this tumor entity. In the present study we tested the effect of histone deacetylase (HDAC) inhibition using depsipeptide (also known as romidepsin, FK228, FR901228 or NSC-630176) in cHL cell lines in vitro. Molecular mechanisms of toxicity were analyzed using RNA expression analysis and functional assays. It is shown that depsipeptide is effective at submicromolar concentrations and acts mainly by apoptosis induction, upregulation of p21 and cell cycle inhibition in G2/M. Of special note, HDAC mediated toxicity in H-RS cells does not require RelA/p65 downregulation, which was previously shown to drive the malignant phenotype of H-RS cells. In summary, depsipeptide induced protein acetylation results in transcriptional changes of a large number of pathogenetically relevant genes and increased RelA/p65 binding activity in cHL cell lines. Our preclinical data suggest that HDAC inhibition using depsipeptide might be a promising approach for the treatment of cHL patients.

CD200 plays a key role in regulating the immune system and has been shown to be upregulated on the surface of different tumors including chronic lymphocytic leukemia. In this study we addressed the effects of CD200 over-expression in CLL cells on autologous T cells in a mixed lymphocyte reaction system. We used native and CD40 ligand (CD40L)-stimulated CLL cells as antigen-presenting cells (APCs) to expand autologous T cells of 14 patients. T cell proliferation over 3 weeks of in vitro culture was significantly enhanced compared to control cells when using CD40L-stimulated APCs and the anti-CD200 antibody 1B9 (p=0.0004). CD200 blockade was further shown to stimulate antigen-specific T cell responses towards the CLL-associated antigen fibromodulin (p=0.04). Finally, the number of CD4+/CD25high/FOXP3+ T cells (T(reg)) was significantly decreased adding anti-CD200 antibody (p=0.04). In summary, CD200 blockade may provide therapeutic benefits in CLL by augmenting an antigen-specific T cell response with suppression of regulatory T cells.

Chronic lymphocytic leukemia (CLL) is characterised by resistance to apoptotic stimuli, mediated by overexpression of anti-apoptotic factors or extracellular survival signals. In this context, TOSO, also known as Fas-inhibitory molecule 3, was identified as a candidate gene over-expressed in CLL. TOSO is a transmembrane protein that inhibits Fas-mediated apoptosis by binding Fas-associated death domain via its C-terminal intracellular domain. In CLL, high levels of TOSO expression have been correlated with more aggressive disease, being associated with high leukocyte count, advanced Binet stage, need for chemotherapy and unmutated IgV(H) gene status. Also, the CD38(+) CLL subset with proliferative activity showed enhanced TOSO expression. B-cell receptor-stimulation was identified as positive regulator of TOSO expression, potentially providing a functional mechanism for aberrant TOSO expression in CLL. In contrast, CD40-ligand signalling reduces expression of TOSO, possibly explaining previously observed Fas-sensitisation by CD40-ligand in gene therapy trials. Both the association with unmutated IgV(H) gene status and the specific induction of TOSO via the BCR suggest autoreactive BCR signalling involving TOSO as a mediator of resistance to apoptosis in CLL. Further studies will reveal the functional context of TOSO in CLL and B cell biology. Surface expression of TOSO will enable antibody-based targeting of this novel CLL-antigen.

MicroRNAs (miRNAs) are small, gene encoded RNAs which are able to influence gene expression in binding to the 3'UTR of mRNAs. Compared to healthy tissues, the global expression of miRNAs in cancerous tissue is frequently down-regulated. Likewise in chronic lymphocytic leukemia (CLL), down-regulation of several miRNAs has been reported. Analysis of miRNA promoters for epigenetic modifications revealed a stronger methylation of down-regulated miRNAs in CLL. To date, several target genes affected by deregulated miRNAs have been identified that have impact on CLL pathogenesis. The best-described consequence of miRNA deregulation is for miRNA-15/16 cluster deletion, which is frequently down-regulated in a subgroup of patients with CLL carrying 13q14 deletion. So far, models for miRNA deregulation have addressed just single miRNAs. For assessment of complete miRNA deregulation, further evaluation of the results from microarray studies is needed. Previously we identified the oncogene PLAG1, whose expression is affected by various miRNAs deregulated in CLL. The involvement of miRNAs in PLAG1 expression was shown to be relevant in pleomorphic adenomas of the salivary gland, too. As PLAG1 is highly overexpressed, and its target genes appear to be deregulated in CLL, e.g. BCL-2, PLAG1 is a putative new relevant oncogene involved in the pathogenesis of CLL.

We would like to complement our recently reported data on the detection of the Merkel cell polyomavirus (MCPyV) in chronic lymphocytic leukemia (CLL) cells. 1 We have shown that MCPyV could be identified by PCR in highly purified CLL cells of 19 of 70 (27.1%) CLL patients. In 6 cases, ...