Mir-34a Mimics Are Potential Therapeutic Agents for p53-Mutated and Chemo-Resistant Brain Tumour Cells

Chemotherapeutic drug resistance and relapse remains a major challenge for paediatric (medulloblastoma) and adult (glioblastoma) brain tumour treatment. Medulloblastoma tumours and cell lines with mutations in the p53 signalling pathway have been shown to be specifically insensitive to DNA damaging agents. The aim of this study was to investigate the potential of triggering cell death in p53 mutated medulloblastoma cells by a direct activation of pro-death signalling downstream of p53 activation. Since non-coding microRNAs (miRNAs) have the ability to fine tune the expression of a variety of target genes, orchestrating multiple downstream effects, we hypothesised that triggering the expression of a p53 target miRNA could induce cell death in chemo-resistant cells. Treatment with etoposide, increased miR-34a levels in a p53-dependent fashion and the level of miR-34a transcription was correlated with the cell sensitivity to etoposide. miR-34a activity was validated by measuring the expression levels of one of its well described target: the NADH dependent sirtuin1 (SIRT1). Whilst drugs directly targeting SIRT1, were potent to trigger cell death at high concentrations only, introduction of synthetic miR-34a mimics was able to induce cell death in p53 mutated medulloblastoma and glioblastoma cell lines. Our results show that the need of a functional p53 signaling pathway can be bypassed by direct activation of miR-34a in brain tumour cells

Remote sensing reveals how armed conflict regressed woody vegetation cover and ecosystem restoration efforts in Tigray (Ethiopia)

In recent years, armed conflicts are globally on the rise, causing drastic human and environmental harm. The Tigray war in Ethiopia is one of the recent violent conflicts that has abruptly reversed decades of ecosystem restoration efforts. This paper analyzes changes in woody vegetation cover during the period of armed conflict (2020–2022) using remote sensing techniques, supplemented by field testimony and secondary data. Extent of woody vegetation cover was analyzed using Normalized Difference Vegetation Index (NDVI) thresholding method from Sentinel 2 images in Google Earth Engine, and scale of de-electrification was qualitatively analyzed from Black Marble HD nighttime lights dataset, acquired from NASA's Black Marble team. The magnitude, direction as well as the mechanisms of change in woody vegetation cover varied across the region and over time. Tigray's woody vegetation cover fluctuated within 20% of the landmass. Mainly scattered to mountainous areas, the dry Afromontane forest cover declined from about 17% in 2020 to 15% in 2021, and 12% in 2022. About 17% of the overall decline was observed between 500 m and 2000 m elevation, where there is higher anthropogenic pressure. Land restoration practices meant to avert land degradation and desertification were interrupted and the area turned warfare ground. In many areas, forests were burned, the trees cut and the area became barren. The suspension of public services such as electricity for household or industrial use created heavy reliance on firewood and charcoal, further threatening to compound weather and climate. The magnitude of disturbance in a region that is already at a very high risk of desertification requires urgent national and international attention. Continued ecosystem disturbance could eventually make the domain part of a wider desert connecting the Sahel to the Afar Triangle, a scenario which may render the area uninhabitable.</p

Bispecific antibodies tethering innate receptors induce human tolerant-dendritic cells and regulatory T cells

There is an urgent need for alternative therapies targeting human dendritic cells (DCs) that could reverse inflammatory syndromes in many autoimmune and inflammatory diseases and organ transplantations. Here, we describe a bispecific antibody (bsAb) strategy tethering two pathogen-recognition receptors at the surface of human DCs. This cross-linking switches DCs into a tolerant profile able to induce regulatory T-cell differentiation. The bsAbs, not parental Abs, induced interleukin 10 and transforming growth factor β1 secretion in monocyte-derived DCs and human peripheral blood mononuclear cells. In addition, they induced interleukin 10 secretion by synovial fluid cells in rheumatoid arthritis and gout patients. This concept of bsAb-induced tethering of surface pathogen-recognition receptors switching cell properties opens a new therapeutic avenue for controlling inflammation and restoring immune tolerance

African Linguistics in Central and Eastern Europe, and in the Nordic Countries

Non peer reviewe

Contrôle de l'autophagie selon le niveau énergétique et nutritionnel de la cellule chez les mammifères (rôle des kinases AMPK et mTOR)

PARIS-BIUSJ-Thèses (751052125) / SudocSudocFranceF

[PI3 kinases and the control of autophagia]

Macroautophagy or autophagy is a degradative pathway terminating in the lysosomal compartment after the formation of a cytoplasmic vacuole that engulfs macromolecules and organelles. The recent discovery of the molecular controls of autophagy that are common to eukaryotic cells from yeast to human suggests that the role of autophagy in cell functioning is far beyond its nonselective degradative capacity. The downregulation of autophagy observed in cancer cells is associated with tumor progression. The regulation of autophagy by signalling pathways overlaps with the control of cell growth, proliferation, cell survival and death. Two of these pathways play an important role in control of autophagy, the class I and III PI3K pathways. Several tumor suppressor genes (PTEN, TSC1 and 2, p53) involved in the class I PI3K mTOR signalling network have been shown to stimulate autophagy. In contrast, the oncoproteins involved in this network (Ras, class I PI3K and Akt) have the opposite effect. These findings, together with the discovery that Beclin 1, which forms a complex with the class III PI3K to initiate autophagy, is a tumor suppressor gene product give credibility of the idea that autophagy is a tumor suppressor mechanism. However, cancer cells sometimes mobilize autophagic capacities in response to various stimuli, suggesting that they can also exploit autophagy for their own benefit

Tocilizumab Contributes to the Inflammatory Status of Mature Dendritic Cells through Interleukin-6 Receptor Subunits Modulation

International audienceTocilizumab, a humanized anti-IL-6 receptor α (IL-6Rα) is widely used in the treatment of a panel of pathologies such as adult and juvenile rheumatoid arthritis (RA) and the systemic form of juvenile idiopathic arthritis in children. Its indications are expected to be largely extended to other inflammatory diseases in close future. Dendritic cells (DCs) appear to be deeply involved in the immunopathology of these diseases, yet the effects of tocilizumab on these cells were poorly studied. In this study, we explored the effect of tocilizumab on the regulation of IL-6R subunits [gp130, soluble form of IL-6Rα (sIL-6Rα), and mIL-6Rα] in human monocyte-derived DCs. Human DCs were derived from CD14 + monocytes purified with beads with IL-4 and granulocyte macrophage colony-stimulating factor. Ex vivo cultures of DCs were performed in the presence of tocilizumab. Using lipopolysaccharide (LPS) maturation of DCs, we demonstrated that tocilizumab did not inhibit IL-6 secretion, enhanced mIL-6Rα expression, and largely increased sIL-6Rα secretion. MAPK modulated STAT3 phosphorylation and surface expression of IL-6Rα in LPS-DCs. Tocilizumab had no impact on STAT3 phosphorylation in LPS-DCs while both LPS and IL-6 increased its activation. Tocilizumab modulated the regulation of IL-6R subunits leading to an inflammatory status of DCs and a massive secretion of IL-6Rα. Our results demonstrate that DCs acquire a pro-inflammatory profile following tocilizumab treatment, becoming a major source of IL-6 trans-signaling activation that might explain the poor clinical benefit in some RA patients

Expression of WT p53 does not restore p53 activity in MEB-Med8A cells.

<p>(<b>A–C</b>) D283-MED cells were co-transfected with p53-dsRedXP and MDM2-YFP and imaged using time lapse confocal microscopy. The time of etoposide stimulation is represented by the vertical dotted line. The level of p53 and MDM2 were assessed by measuring fluorescence intensity in single cells over time, which were normalised to the baseline fluorescence measured prior to etoposide addition. (B, C): Example of 5 single cell traces and the average fluorescent intensity (red line) of all cells are shown (N = 2, n = 33). (<b>D–F</b>) MEB-Med8A cells were co-transfected and imaged as in (A–C). (E–F): Example of 5 single cell traces and the average fluorescent intensity (red line) of all cells are shown (N = 2, n = 22). (<b>G</b>) A stack column showing the percentage of MB cells with p53 or MDM2 expression above threshold level upon etoposide treatment. Threshold was calculated as average intensity of untreated control +2 SD. D283 cells (N = 2, n = 33); Med8 cells (N = 2, n = 22).</p

miR-34a-mimic induces cell death in p53 mutated MB and GBM cells.

<p>(<b>A</b>) D283-MED, MEB-Med8A MB, U87MG and T98G cells were transfected with [100 nM] miR-34a mimics or non-specific mimic miRIDIAN control and expressed for 72 hours prior to cell viability assessment by MTS assay. Cell viability was normalised to cells transfected with the non-specific mimic control. Data shown are the mean ± S.E.M of four independent experiments. One-way ANOVA followed by Bonferroni test was performed (*indicates p<0.05). (<b>B</b>) D283-MED and MEB-Med8A MB were transfected with [50 nM] or [100 nM] of miR-34a mimic or [50 nM] of non-specific miRIDIAN control for 48 h. Expression levels of SIRT1, c-Myc and Bcl-2 were assessed by western-blot. (<b>C</b>) 2 gels form independent experiments were quantified by densitometry analysis. The plot shown is the result of the quantification relative to actin levels and normalised to cells transfected with the non-specific miRIDIAN control ± sd. (<b>D</b>) D283-MED and MEB-Med8A MB were treated with [20 µM] etoposide for indicated time points. Expression levels of SIRT1 and c-Myc were assessed by western-blot. (<b>E</b>) 2 gels form independent experiments were quantified by densitometry analysis. The graph shown is the result of the quantification normalised to untreated cells at t0 ± sd.</p