Rôle des espèces réactives de l'oxygène dans l'induction de mécanismes d'adaptation au cadmium dans les cellules CACO-2

Le cadmium (Cd) est un métal toxique, inducteur de stress oxydatif, dont la principale source de contamination pour l'humain non-fumeur est la nourriture. L'épithélium intestinal est la première barrière de l'organisme franchie par le Cd ingéré. Lors de sa phase proliférative, la lignée cellulaire Caco-2 est représentative des précurseurs d'entérocytes et, lors de sa phase différenciée, des entérocytes matures de l'épithélium intestinal. Un prétraitement de 24 h à 10 µM de Cd induit une tolérance au Cd dans les cellules prolifératives, mais pas dans les cellules Caco-2 différenciées alors que ces dernières sont, de façon naturelle, moins sensibles. Les objectifs de cette étude sont d'évaluer, en fonction du stade de différenciation entérocytaire, le rôle du stress oxydatif dans l'induction de cette tolérance et dans la toxicité aiguë du Cd, ainsi que de comparer la tolérance induite par le Zinc (Zn) à celle induite par le Cd. Les hypothèses de cette étude sont: i) le stress oxydatif est impliqué dans le mécanisme de résistance acquise des cellules prolifératives, ii) la MT-lIa et la HSP70 ne sont pas essentielles à ce processus de résistance et iii) les résistances acquises induites par le Zn et le Cd impliquent des processus différents. La méthodologie de cette étude comprend des techniques de culture cellulaire, des tests de viabilité cellulaire, des analyses d'expression de la MT-lIa et de la HSP70 par RT-PCR, des dosages de contenus en thiols intracellulaires et d'activité de la catalase (CAT) et de la glutathion peroxidase (GSH-Px), des mesures d'accumulation cellulaire de

Autophagy drives fibroblast senescence through MTORC2 regulation

Sustained macroautophagy/autophagy favors the differentiation of fibroblasts into myofibroblasts. Cellular senescence, another means of responding to long-term cellular stress, has also been linked to myofibroblast differentiation and fibrosis. Here, we evaluate the relationship between senescence and myofibroblast differentiation in the context of sustained autophagy. We analyzed markers of cell cycle arrest/senescence in fibroblasts in vitro, where autophagy was triggered by serum starvation (SS). Autophagic fibroblasts expressed the senescence biomarkers CDKN1A/p21 and CDKN2A/p16 and exhibited increased senescenceassociated GLB1/beta-galactosidase activity. Inhibition of autophagy in serum-starved fibroblasts with 3-methyladenine, LY294002, or ATG7 (autophagy related 7) silencing prevented the expression of senescence-associated markers. Similarly, suppressing MTORC2 activation using rapamycin or by silencing RICTOR also prevented senescence hallmarks. Immunofluorescence microscopy showed that senescence and myofibroblast differentiation were induced in different cells, suggesting mutually exclusive activation of senescence and myofibroblast differentiation. Reactive oxygen species (ROS) are known inducers of senescence and exposing fibroblasts to ROS scavengers decreased ROS production during SS, inhibited autophagy, and significantly reduced the expression of senescence and myofibroblast differentiation markers. ROS scavengers also curbed the AKT1 phosphorylation at Ser473, an MTORC2 target, establishing the importance of ROS in fuelling MTORC2 activation. Inhibition of senescence by shRNA to TP53/p53 and shRNA CDKN2A/p16 increased myofibroblast differentiation, suggesting a negative feedback loop of senescence on autophagy-induced myofibroblast differentiation. Collectively, our results identify ROS as central inducers of MTORC2 activation during chronic autophagy, which in turn fuels senescence activation and myofibroblast differentiation in distinct cellular subpopulations

DCBLD1 is associated with the integrin signaling pathway and has prognostic value in non-small cell lung and invasive breast carcinoma

Abstract Germline single nucleotide polymorphisms in the promoter region of the DCBLD1 gene are associated with non-smoking cases of both non-small cell lung carcinoma (NSCLC) and human papillomavirus-negative head and neck cancer. However the clinical relevance and function of DCBLD1 remain unclear. This multicenter retrospective study was designed to evaluate the prognostic value and function of DCBLD1 in the four main solid cancers: NSCLC, invasive breast carcinoma, colorectal adenocarcinoma and prostate adenocarcinoma. We included the following cohorts: GSE81089 NSCLC, METABRIC invasive breast carcinoma, GSE14333 colorectal adenocarcinoma, GSE70770 prostate adenocarcinoma and The Cancer Genome Atlas (TCGA) Firehose Legacy cohorts of all four cancers. DCBLD1 gene expression was associated with a worse overall survival in multivariate analyses for both NSCLC cohorts (TCGA: P = 0.03 and GSE81089: P = 0.04) and both invasive breast carcinoma cohorts (TCGA: P = 0.02 and METABRIC: P < 0.001). Patients with high DCBLD1 expression showed an upregulation of the integrin signaling pathway in comparison to those with low DCBLD1 expression in the TCGA NSCLC cohort (FDR = 5.16 × 10–14) and TCGA invasive breast carcinoma cohort (FDR = 1.94 × 10–05)

Quantification and visualization of aerosols in ear, nose, and throat exam and flexible laryngoscopy

OBJECTIVE: To measure and visualize aerosol generation during ear, nose, and throat (ENT) exam and flexible laryngoscopy, as safety recommendations are currently to defer routine and low‐priority examinations. METHODS: Aerosols generated during ENT examination and flexible laryngoscopy were quantified by laser aerosol spectrometry and visualized live by high‐speed imaging during those procedures for three participants who were tested three times for each test. RESULTS: Routine ENT examination and flexible laryngoscopy produce aerosols at levels comparable to normal breathing and speech. CONCLUSION: During ENT examination and flexible laryngoscopy, the practitioner should wear a surgical mask and potentially contaminated surfaces should be cleaned after the procedure. For flexible laryngoscopy, it is recommended in addition that the patient wear a mask over the mouth in case the procedure induces a sneeze. The time during which the patient is unmasked should be minimized. In these settings, the risk to the practitioner is minimal unless the patient is sneezing or symptomatic. LEVEL OF EVIDENCE:

Senolytic Targeting of Bcl-2 Anti-Apoptotic Family Increases Cell Death in Irradiated Sarcoma Cells

Radiotherapy (RT) is a key component of cancer treatment. Most of the time, radiation is given after surgery but for soft-tissue sarcomas (STS), pre-surgical radiation is commonly utilized. However, despite improvements in RT accuracy, the rate of local recurrence remains high and is the major cause of death for patients with STS. A better understanding of cell fates in response to RT could provide new therapeutic options to enhance tumour cell killing by RT and facilitate surgical resection. Here, we showed that irradiated STS cell cultures do not die but instead undergo therapy-induced senescence (TIS), which is characterized by proliferation arrest, senescence-associated &beta;-galactosidase activity, secretion of inflammatory cytokines and persistent DNA damage. STS-TIS was also associated with increased levels of the anti-apoptotic Bcl-2 family of proteins which rendered cells targetable using senolytic Bcl-2 inhibitors. As oppose to radiation alone, the addition of senolytic agents Venetoclax (ABT-199) or Navitoclax (ABT-263) after irradiation induced a rapid apoptotic cell death in STS monolayer cultures and in a more complex three-dimensional culture model. Together, these data suggest a new promising therapeutic approach for sarcoma patients who receive neoadjuvant RT. The addition of senolytic agents to radiation treatments may significantly reduce tumour volume prior to surgery and thereby improve the clinical outcome of patients

Senolytic Targeting of Bcl-2 Anti-Apoptotic Family Increases Cell Death in Irradiated Sarcoma Cells

Radiotherapy (RT) is a key component of cancer treatment. Most of the time, radiation is given after surgery but for soft-tissue sarcomas (STS), pre-surgical radiation is commonly utilized. However, despite improvements in RT accuracy, the rate of local recurrence remains high and is the major cause of death for patients with STS. A better understanding of cell fates in response to RT could provide new therapeutic options to enhance tumour cell killing by RT and facilitate surgical resection. Here, we showed that irradiated STS cell cultures do not die but instead undergo therapy-induced senescence (TIS), which is characterized by proliferation arrest, senescence-associated &beta;-galactosidase activity, secretion of inflammatory cytokines and persistent DNA damage. STS-TIS was also associated with increased levels of the anti-apoptotic Bcl-2 family of proteins which rendered cells targetable using senolytic Bcl-2 inhibitors. As oppose to radiation alone, the addition of senolytic agents Venetoclax (ABT-199) or Navitoclax (ABT-263) after irradiation induced a rapid apoptotic cell death in STS monolayer cultures and in a more complex three-dimensional culture model. Together, these data suggest a new promising therapeutic approach for sarcoma patients who receive neoadjuvant RT. The addition of senolytic agents to radiation treatments may significantly reduce tumour volume prior to surgery and thereby improve the clinical outcome of patients

Enhancing Blue Emission in Ce Doped Silicon Oxynitrides Based Electroluminescent Devices

International audienceCe-doped SiO x N y and SiAlON matrices are promising materials for blue LED applications. The uniqueness of this approach stems from the fact that SiO x N y , as a host, combines specific properties of individual SiO x and SiN y matrices like solubility, efficient emission, 5 eV gap, with a broad excitation range from 400 nm to 500 nm of Ce 3+ ions due to the 4f-5d transitions. Furthermore, the co-doping with aluminum enhances the Ce 3+ emission. In this work, we fabricated electroluminescent devices using SiO x N y :Ce 3+ and SiAlON:Ce 3+ as active layers and investigated the resulting emission under optical and electrical excitations as a function of nitrogen, cerium and aluminum concentrations. I-V measurements were conducted to determine the SiO x N y :Ce 3+ layer electrical parameters. Charge transport through the devices obeys the Poole-Frenkel conduction mechanism. It was demonstrated that by optimizing the SiO x N y :Ce 3+ growth parameters, an improvement of electroluminescence yield can be achieved with a maximum intensity obtained for devices with cerium content of 4 at.%. Rare earth (RE) doped silicon based materials have been extensively investigated in the past few years. Various hosts were doped with Er 3+ ions that emit at 1.5 μm corresponding to the maximum transparency of silica used in telecommunications. 1 For the Ce 3+ ion, up to date, only a few studies have been reported on its electrolu-minescence (EL). 2 Among the silicon-based matrices, silica (SiO 2) and silicon nitride (Si 3 N 4) have been explored; however, each of them present certain advantages and drawbacks. In the case of silica matrices , achievement of strong RE 3+ ions emission is limited by a low excitation cross section, 3 a low RE solubility as well as RE clusters formation. 4,5 However, the main drawback limiting SiO 2 : RE 3+ light emitting applications comes from the large bandgap of the matrix (∼9 eV) resulting in low electrical conductivity. On the other hand, Si 3 N 4 with a smaller energy bandgap (4 eV) and reduced tendency of the RE to form clusters, seems to be more suitable for RE doping. 6-8 However, despite these advantages, the emission efficiency from RE 3+ ions in a nitride matrix is much lower than in silica matrix. 9 To capitalize on the RE doping advantages offered by both oxide and nitride silicon matrices, a Ce-doped SiO x N y matrix has been explored by Ramirez et al. 10 It was reported that the maximum EL peak from Ce 3+ ion shifted from 400 nm to 476 nm as function of the nitrogen concentration (i.e. the nephelauxetic effect). 10,11 Koao et al. showed that aluminum co-doping Ce-doped SiO 2 glasses lead to an enhancement of photoluminescence emission. 12 In this work, Ce-doped Si(Al)O x N y layers with a typical thickness of 50 nm were grown by sputter de-position. Photoluminescence (PL) from the SiO x N y :Ce 3+ layers and EL from this active layer were examined for device performance as a function of growth parameters and material composition. Experimental Active layer preparation.-The devices were fabricated in a few step processes. First, the Ce-doped SiO x N y active layer was grown by magnetron reactive sputtering with 8 sccm for Ar and 2 sccm for N 2 on 2-inch diameter (001) p-type silicon wafers. During the growth, the chamber base pressure was fixed at 3 mTorr and the substrate temperature was at room temperature (RT). Additional information on the growth process can be found in the following Reference 11. z Samples were deposited from CeO 2 , Al and Si targets with density of power varied from 0 to 2.1 W.cm −2 , 0.3 to 0.75 W.cm −2 and fixed at 4.5 W/cm 2 , respectively. As-deposited films were then thermally annealed in the 600°C to 1200°C temperature range for 1 h, in nitrogen atmosphere at ambient pressure. Device fabrication.-Figure 1 illustrates the typical fabricated device structure with the indicated specific layers thicknesses. The individual indium tin oxide (ITO) top electrical contacts were deposited on the SiO x N y :Ce 3+ layer by electron beam evaporation using a shadow mask having a set of circular holes with a diameter of 200 μm. In 2 O 3 /SnO 2 (90%/10%) pellets with a diameter of 1 mm or 2 mm were used as sputtering targets. An oxygen flux was maintained in the sputtering chamber during deposition cycle to prevent the formation of oxygen defects in the transparent conducting layer, which would potentially cause EL from ITO layer. The ITO layer thickness was 200 nm. The SiO x N y :Ce 3+ /ITO structure was heated up at a ramp rate of 15°C/min from RT to 600°C and annealed for 1 h in a nitrogen atmosphere at ambient pressure. The bottom metal contact, a 200-nm-thick Al layer, was deposited at RT on the back of the silicon substrate. Figure 1. Schematic layout of fabricated Al/p-Si/SiO x N y :Ce 3+ /ITO device

Single Nucleotide Polymorphism rs6942067 Is a Risk Factor in Young and in Non-Smoking Patients with HPV Negative Head and Neck Squamous Cell Carcinoma

Genetic factors behind the increasing incidence of human papillomavirus (HPV) negative head and neck squamous cell carcinoma (HNSCC) in young non-smokers are suspected, but have not been identified. Recently, rs6942067, a single nucleotide polymorphism (SNP) located upstream of the DCBLD1 gene, was found associated with non-smoking lung adenocarcinoma. To validate if this SNP is also implicated in HNSCC, participants of The Cancer Genome Atlas HNSCC cohort were investigated for rs6942067 status, associated DCBLD1 expression, and clinical characteristics. Occurrence of the rs6942067 GG genotype is significantly higher in young and in HPV negative non-smoking HNSCC than in other HNSCC. Additionally, rs6942067 GG is associated with higher DCBLD1 expression in HNSCC and patients with high DCBLD1 expression have a worse overall survival at three years, both in univariate and multivariate analysis. Furthermore, high DCBLD1 expression is associated with activation of the integrin signaling pathway and its phosphorylation with EGFR and MET. Collectively, these findings suggest that DCBLD1 plays a critical role in HNSCC and demonstrate an association between rs6942067 and clinical characteristics of young age and HPV negative non-smoking status in HNSCC patients