Chemokine CXCL13 is overexpressed in the tumour tissue and in the peripheral blood of breast cancer patients

The abilities of chemokines in orchestrating cellular migration are utilised by different (patho-)biological networks including malignancies. However, except for CXCR4/CXCL12, little is known about the relation between tumour-related chemokine expression and the development and progression of solid tumours like breast cancer. In this study, microarray analyses revealed the overexpression of chemokine CXCL13 in breast cancer specimens. This finding was confirmed by real-time polymerase chain reaction in a larger set of samples (n=34) and cell lines, and was validated on the protein level performing Western blot, ELISA, and immunohistochemistry. Levels of CXCR5, the receptor for CXCL13, were low in malignant and healthy breast tissues, and surface expression was not detected in vitro. However, we observed a strong (P=0.0004) correlation between the expressions of CXCL13 and CXCR5 in breast cancer tissues, indicating a biologically relevant role of CXCR5 in vivo. Finally, we detected significantly elevated serum concentrations of CXCL13 in patients with metastatic disease (n=54) as compared with controls (n=44) and disease-free patients (n=48). In conclusion, CXCL13 is overexpressed within breast cancer tissues, and increased serum levels of this cytokine can be found in breast cancer patients with metastatic disease pointing to a role of CXCL13 in the progression of breast cancer, suggesting that CXCL13 might serve as a useful therapeutic target and/or diagnostic marker in this malignancy

Multiparameter Characterization Confirms Apoptosis as the Primary Cause of Reduced Self-renewal Capacity in Cultured Human Fetal Neural Stem Cells

Background: Human fetal striatum-derived neural stem cells (hfsNSCs) are important in regenerative medicine; however, their ability to self-renew diminishes quickly following passages in culture. Typically when hfsNSC-derived neurospheres are dissociated by accutase, more than 90% of the cells survive, but only 6-8% of the cells are able to form secondary neurospheres. Our hypothesis is that the hfsNSCs that are unable to form new neurospheres become apoptotic. Methods/Results: Because the NSC apoptosis process has never been characterized in detail, we characterized hfsNSC apoptosis using multiparameter analysis and determined that the majority of hfsNSCs undergo apoptosis after passaging, which leads to a reduction in self-renewal. The replacement of trituration with vortexing decreases apoptosis, increases self-renewal, and does not affect NSC differentiation. When we used live cell staining with Annexin V, Hoechst 33342, and PI together, the apoptotic index was in agreement with what could be obtained using fixed-cell staining methods, including TUNEL and activated caspase-3 immunocytochemistry. NSC apoptosis could be divided into 9 stage types based on our live cell assay. Several types during early and late stages had similar staining profiles that could be further discriminated based on cell size. Conclusion: Apoptosis largely contributes to the low self-renewal of neurospheres, and replacing trituration with vortexing aided in alleviating NSC apoptosis. Multiparameter analysis is required for the identification of NSC apoptosis, particularly when live cell staining is used

Intravenously Delivered Allogeneic Mesenchymal Stem Cells Bidirectionally Regulate Inflammation and Induce Neurotrophic Effects in Distal Middle Cerebral Artery Occlusion Rats Within the First 7 Days After Stroke

Background/Aims: Neurotrophic effects and immunosuppression are the main therapeutic mechanisms of mesenchymal stem cells (MSCs) in stroke treatment. Neurotrophins are produced by graft cells, host neurons, astrocytes, and even microglia/macrophages. Meanwhile, MSCs can increase inflammation if they are not sufficiently induced by pro-inflammatory cytokines. We examined whether intravenously transplanted bone marrow MSCs (BM-MSCs) increase inflammation in distal middle cerebral artery occlusion (dMCAO) rats, how long the increased inflammation effect persists for, and what the final therapeutic outcomes will be. We also tested the neurotrophic role of BM-MSCs and attempted to identify the neurotrophin-producing cells. Methods: At 1 h after dMCAO was performed on Sprague-Dawley rats, allogeneic BM-MSCs were transplanted intravenously. The infarct volume was examined by Tetrazolium Red staining at 2 days (day 2), and the behavioral tests (cylinder test and grid walking test) were performed at 2, 4 (day 4) and 7 days (day 7) after transplantation. The concentrations of inflammation related cytokines and neurotrophins in the ischemic cortex, ipsilateral striatum, and serum, were measured using ELISA at days 2-7. The cell source of neurotrophins was observed by immunohistochemistry. Results: The transplanted cells were mainly found in the infarct border zone (IBZ) of the brain. Infarct volume was reduced and behavioral outcomes were improved at 2 days after ischemia. In the striatum and circulation, BM-MSC transplantation increased inflammation at day 2 and decreased it at day 7. At days 2-7, insulin-like growth factor-1 (IGF-1) and brain-derived neurotrophic factor (BDNF) concentrations in the ischemic core of the cortex were significantly higher in the BM-MSC group than in the ischemia vehicle group. IGF-1 and BDNF were derived mainly from host microglia/macrophages in the ischemic core, and transplanted cells in the IBZ. At day 2, BM-MSC transplantation significantly increased the number of IGF-1+CD68+ and BDNF+Iba-1+ double positive cells in the ischemic core cortex. Conclusions: Although increased inflammation, BM-MSCs were still beneficial to dMCAO recovery at day 2. The immunopromoting effect of MSCs was transient and shifted to an immunosuppressive action at day 7. The neurotrophic factors IGF-1 and BDNF, which were mainly derived from transplanted BM-MSCs and host microglia/macrophages, contributed to the therapeutic effects from day 2 to day 7

Reconstitution of the DTX3L-PARP9 complex reveals determinants for high affinity heterodimerization and multimeric assembly

Abstract Ubiquitination and ADP-ribosylation are post-translational modifications that play major roles in pathways including the DNA damage response and viral infection. The enzymes responsible for these modifications are therefore potential targets for therapeutic intervention. DTX3L is an E3 Ubiquitin ligase that forms a heterodimer with PARP9. In addition to its ubiquitin ligase activity, DTX3L–PARP9 also acts as an ADP-ribosyl transferase for Gly76 on the C-terminus of ubiquitin. NAD⁺-dependent ADP-ribosylation of ubiquitin by DTX3L–PARP9 prevents ubiquitin from conjugating to protein substrates. To gain insight into how DTX3L–PARP9 generates these post-translational modifications, we produced recombinant forms of DTX3L and PARP9 and studied their physical interactions. We show the DTX3L D3 domain (230–510) mediates the interaction with PARP9 with nanomolar affinity and an apparent 1 : 1 stoichiometry. We also show that DTX3L and PARP9 assemble into a higher molecular weight oligomer, and that this is mediated by the DTX3L N-terminal region (1–200). Lastly, we show that ADP-ribosylation of ubiquitin at Gly76 is reversible in vitro by several Macrodomain-type hydrolases. Our study provides a framework to understand how DTX3L–PARP9 mediates ADP-ribosylation and ubiquitination through both intra- and inter-subunit interactions