CD95 promotes metastatic spread via Sck in pancreatic ductal adenocarcinoma

Cancer stem cells (CSCs) have been implicated in the initiation and maintenance of tumour growth as well as metastasis. Recent reports link stemness to epithelial–mesenchymal transition (EMT) in cancer. However, there is still little knowledge about the molecular markers of those events. In silico analysis of RNA profiles of 36 pancreatic ductal adenocarcinomas (PDAC) reveals an association of the expression of CD95 with EMT and stemness that was validated in CSCs isolated from PDAC surgical specimens. CD95 expression was also higher in metastatic pancreatic cells than in primary PDAC. Pharmacological inhibition of CD95 activity reduced PDAC growth and metastasis in CSC-derived xenografts and in a murine syngeneic model. On the mechanistic level, Sck was identified as a novel molecule indispensable for CD95's induction of cell cycle progression. This study uncovers CD95 as a marker of EMT and stemness in PDAC. It also addresses the molecular mechanism by which CD95 drives tumour growth and opens tantalizing therapeutic possibilities in PDAC.

Saccharomyces cerevisiae as delivery vehicle for a NY-ESO-1 protein vaccine

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Background: Vaccine strategies that target or activate dendritic cells in order to elicit potent cellular immunity are currently the subject of intense research. Here we report that genetically engineered yeast expressing the full-length tumor associated antigen NY-ESO-1 are a versatile host for protein production eliciting MHC class I and II T-cell responses. Methods: The pYD1 yeast display vector was chosen for full length NY-Eso-1 protein (pNY-ESO-1) expression. NY-ESO-1 and SSX-2 (as control) protein were affinity purified on. IFN-g ELISPOT assays were performed in triplicates on nitrocellulose-lined 96-well plates. MHC class I cross-presentation of peptide epitopes was demonstrated by blocking T-cell responses against DCs. For this purpose, antigen or peptide pulsed DCs were labeled with different doses (100, 10, 1 μg/ml) of antibodies specific for HLA-A2/peptide complexes (HLA-A2/ NY-Eso-1157–165; 3M4E5) or an irrelevant antibody (specific for HLA-A2/IMP58–66) as control. Results: Highest level of NY-ESO-1 expression was detected on the cell wall of wt EBY100 strain with lower expression levels on PMT deficient strains PMT-2 and PMT-4. After protein feeding of immature DCs, NY-ESO-1 157–165 peptide cross-presentation was detected by 3M4E5 and an antigen-specific CD8+ T cell clone. There was a strong positive correlation between the amount of Aga2p-NY-ESO-1 protein (0–15μg/ml) and peptide presentation. Specific T-cell recognition of NY-Eso-1 157–165/HLA-A2 complexes was validated by blocking experiments with Fab 3M4E5. Pre-incubation of protein fed DCs with the antibody at different concentrations (0–100 μg/ml) resulted in a significant reduction (p< 0.05) of spot numbers. Efficient presentation and T-cell recognition of epitope 157–165 was only adequately detectable when protein produced by EBY100 wt yeast strain was used (p < 0.05). MHC class II presentation was studied in an autologous setting using a T-cell line recognising the NY-ESO-1 157–170 in HLA-DP4 context revealing that NY-ESO-1 protein produced in yeast was efficiently taken up and presented. Conclusions: Together, these data add further evidence that yeast expressing recombinant proteins can be used for vaccine purposes and that antigen uptake in APC depends on glycoslation of yeast expressed antigens.

No significant financial relationships to disclose.

Control of neuronal branching by the death receptor CD95 (Fas/Apo-1)

The CD95 (Apo-1/Fas)/CD95 ligand (CD95L) system is best characterized as a trigger of apoptosis. Nevertheless, despite broad expression of CD95L and CD95 in the developing brain, absence of functional CD95 (lpr mice) or CD95L (gld mice) does not alter neuronal numbers. Here, we report that in embryonic hippocampal and cortical neurons in vivo and in vitro CD95L does not induce apoptosis. Triggering of CD95 in cultured immature neurons substantially increases neurite branches by promoting their formation. The branching increase occurs in a caspase-independent and death domain-dependent manner and is paralleled by an increase in the nonphosphorylated form of Tau. Most importantly, lpr and gld mutants exhibit a reduced number of dendritic branches in vivo at the time when synapse formation takes place. These data reveal a novel function for the CD95 system and add to the picture of guidance molecules in the developing brain.

Therapeutic neutralization of CD95-ligand and TNF attenuates brain damage in stroke

Stroke is the third most common cause of death in the Western world. The mechanisms of brain damage in the affected areas are largely unknown. Hence, rational treatment strategies are limited. Previous experimental evidence suggested that cerebral lesions were less prominent in CD95 (APO-1/Fas)-deficient (lpr) than in wild-type mice. Additional results strongly suggested that the CD95-ligand (CD95L) was a major cause of neuronal autocrine suicide in the penumbra. These data and the assumption that death-receptor systems might determine stroke-related damage in the brain prompted us to examine these systems in in vitro and in vivo models of ischemia. We showed that hybrids of TNF-deficient and gld mice were strongly resistant towards stroke-induced damage. To determine the mechanism of action of TNF and CD95L, we separately investigated their influence on primary ischemic death and secondary inflammatory injury. Inhibition of both TNF and CD95L in vitro prevented death of primary neurons induced by oxygen-glucose deprivation and reperfusion. The recruitment of inflammatory cells to the ischemic hemisphere was abrogated in the absence of both TNF and CD95L. Significantly, mice injected with a mixture of neutralizing anti-TNF and anti-CD95L antibodies 30 min after induction of stroke showed a marked decrease in both infarct volumes and mortality. Accordingly, the locomotor performance of these animals was not significantly impaired in comparison to sham-operated animals. These data reveal that inhibition of TNF and CD95L blocks stroke-related damage at two levels, the primary ischemic and the secondary inflammatory injury. These results offer new approaches in stroke treatment.