Rôle du CD46 dans le développement et la fonction des lymphocytes T régulateurs naturels

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Rôle des tachykinines dans la modulation de l'apoptose des lymphocytes T CD4+ induite par l'activation de Fas

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Développement des lymphocytes T : mécanismes de différenciation extrathymique

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.

Les lymphocytes T mémoires... une question de survie

Mémoire numérisé par la Direction des bibliothèques de l'Université de Montréal.

Traitement du cancer par transfert adoptif de lymphocytes T dirigés contre un antigène mineur d'histocompatibilité

Thèse numérisée par la Direction des bibliothèques de l'Université de Montréal.

Enhancement of the Cytotoxic Effect of Anticancer Agent by Cytochrome c Functionalised Hybrid Nanoparticles in Hepatocellular Cancer Cells

Treatment of hepatocellular cancer with chemotherapeutic agents has limited successin clinical practice and their efficient IC50 concentration would require extremely highdoses of drug administration which could not be tolerated due to systemic side effects.In order to potentiate the efficacy of anticancer agents we explored the potentialof co-treatment with pro-apoptotic Cytochrome c which activates the apoptoticpathway downstream of p53 that is frequently mutated in cancer. To this end weused hybrid iron oxide-gold nanoparticles as a drug delivery system to facilitate theinternalisation of Cytochrome c into cultured HepG2 hepatocellular carcinoma cells.Our results showed that Cytochrome c can be easily conjugated to the gold shell ofthe nanoparticles which are readily taken up by the cells. We used Cytochrome cin concentration (0.2μgmL-1) below the threshold required to induce apoptosis onits own. When the conjugate was administered to cells treated by doxorubicin, itsignificantly reduced its IC50 concentration from 9μgmL-1 to 3.5μgmL-1 as detectedby cell viability assay, and the efficiency of doxorubicin on decreasing viability ofHepG2 cells was significantly enhanced in the lower concentration range between0.01μgmL-1 to 5μgmL-1. The results demonstrate the potential of the application oftherapeutic proteins in activating the apoptotic pathway to complement conventionalchemotherapy to increase its efficacy. The application of hybrid iron oxide-goldnanoparticles can also augment the specificity of drug targeting and could serve as amodel drug delivery system for pro-apoptotic protein targeting and delivery.

An in vitro investigation on the cytotoxic and nuclear receptor transcriptional activity of the mycotoxins fumonisin B1 and beauvericin

Fumonisin B1 (FB1) and beauvericin (BEA) are secondary metabolites of filamentous fungi, which under appropriate temperature and humidity conditions may develop on various foods and feeds. To date few studies have been performed to evaluate the toxicological and endocrine disrupting effects of FB1 and BEA. The present study makes use of various in vitro bioassays including; oestrogen, androgen, progestagen and glucocorticoid reporter gene assays (RGAs) for the study of nuclear receptor transcriptional activity, the thiazolyl blue tetrazolium bromide (MTT) assay to monitor cytotoxicity and high content analysis (HCA) for the detection of pre-lethal toxicity in the RGA and Caco-2 human colon adenocarcinoma cells. At the receptor level, 0.001-10μM BEA or FB1 did not induce any agonist responses in the RGAs. However at non-cytotoxic concentrations, an antagonistic effect was exhibited by FB1 on the androgen nuclear receptor transcriptional activity at 10μM and BEA on the progestagen and glucocorticoid receptors at 1μM. MTT analysis showed no decrease in cell viability at any concentration of FB1, whereas BEA showed a significant decrease in viability at 10μM. HCA analysis confirmed that the reduction in the progestagen receptor transcriptional activity at 1μM BEA was not due to pre-lethal toxicity. In addition, BEA (10μM) induced significant toxicity in both the TM-Luc (progestagen responsive) and Caco-2 cells.

Avaliação do efeito citotóxico da lectina da esponja marinha Cliona varians contra células de leucemia mielóide crônica

In this study, a BCR-ABL expressing human chronic myelogenous leukaemia cell line (K562) was used to investigate the antitumoral potential of a novel lectin (CvL) purified from the marine sponge Cliona varians. CvL inhibited the growth of K562 cells with an IC50 value of 70 g/ml, but was ineffective to normal human peripheral blood lymphocytes in the same range of concentrations tested (180 g/ml). Cell death occurred after 72 h of exposure to the lectin and with sign of apoptosis as analysed by DAPI staining. Investigation of the possible effectors of this process showed that cell death occurred in the presence of Bcl-2 and Bax expression, and involved a caspase-independent pathway. Confocal fluorescence microscopy indicated a major role for the lysosomal protease cathepsin B in mediating cell death. Accordingly, pre-incubation of K562 cells with the cathepsin inhibitor L-trans-epoxysuccinyl-L-leucylamido-(4-guanidino)butane (E-64) abolished the cytotoxic effect of CvL. Furthermore, we found upregulation of tumor necrosis factor receptor 1 (TNFR1) and down-modulation of p65 subunit of nuclear factor kappa B (NFB) expression in CvL-treated cells. These effects were accompanied by increased levels of p21 and downmodulation of pRb, suggesting that CvL is capable of cell cycle arrest. Collectively, these findings suggest that cathepsin B acts as death mediator in CvL-induced cytotoxicity possibly in a still uncharacterized connection with the membrane death receptor pathway

Valeur pronostique de CD73 et des lymphocytes T CD8 et optimisation de la vaccination de type GVAX dans le cancer de la prostate

CD73 est un ecto-enzyme qui a été associé à la suppression de l'immunité anti-tumorale. Ses valeurs pronostiques et thérapeutiques ont été mises de l'avant dans plusieurs types de cancer. La première hypothèse du projet est que l'expression de CD73 dans la tumeur prédit le pronostic des patients atteints du cancer de la prostate. L'expression de CD73 a été étudiée par immunofluorescence dans des échantillons de tumeur. Puis, des analyses univariées et multivariées ont été conduites pour déterminer si l'expression de CD73 permet de prédire la récidive biochimique des patients. Nous avons déterminé que CD73 prédit indépendamment le pronostic des patients atteints du cancer de la prostate. De plus, nous avons déterminé que son expression dans le tissu normal adjacent ou dans la tumeur prédit différemment la survenue de la récidive biochimique. La deuxième hypothèse est que l'inhibition de CD73 permet d'améliorer l'efficacité d'un vaccin thérapeutique contre le cancer de la prostate. L'effet d'un vaccin de type GVAX a été étudié dans des souris CD73KO ou en combinaison avec un anticorps ciblant CD73. Nous avons observé que l'efficacité du vaccin était augmentée dans les souris où CD73 était absent. Cependant, la combinaison avec l'anti-CD73 n'a pas permis d'améliorer l'efficacité.

Wild mushrooms and their mycelia as sources of bioactive compounds: antioxidant, anti-inflammatory and cytotoxic properties

Mushrooms are an important source of natural compounds with acknowledged bioactivity. Pleurotus eryngii (DC.) Quél., in particular, is widely recognized for its organoleptic quality and favorable health effects, being commercially produced in great extent. On the other hand, Suillus bellinii (Inzenga) Watling is an ectomycorrhizal symbiont, whose main properties were only reported in a scarce number of publications. Some current trends point toward using the mycelia and the culture media as potential sources of bioactive compounds, in addition to the fruiting bodies. Accordingly, P. eryngii and S. bellinii were studied for their composition in phenolic acids and sterols, antioxidant capacity (scavenging DPPH radicals, reducing power, β-carotene bleaching inhibition and TBARS formation inhibition), anti-inflammatory effect (by down-regulating LPS-stimulated NO in RAW264.7 cells) and anti-proliferative activity (using MCF-7, NCI-H460, HeLa, HepG2 and PLP2 cell lines). Overall, S. bellinii mycelia showed higher contents of ergosterol and phenolic compounds (which were also detected in higher quantity in its fruiting body) and stronger antioxidant activity than P. eryngii. On the other hand, P. eryngii mycelia showed anti-inflammatory (absent in S. bellinii mycelia) and a cytotoxicity similar (sometimes superior) to its fruiting bodies, in opposition to S. bellinii, whose mycelia presented a decreased anti-proliferative activity. Furthermore, the assayed species showed differences in the growth rate and yielded biomass of their mycelia, which should also be considered in further applications.

Biological activities (antibacterial, antifungal and cytotoxic) of secondary metabolites of Ircinia spp.

Sponges are the most primitive of the multicellular, These organisms don’t have any mechanical defense system, so their early appearance in evolution has given them a lot of time for the development of advanced secondary metabolites as chemical defense system. Sponges have the potential to provide drugs from chemical components against diseases. In this investigation the sponge samples, which it is Ircina spp., were collected at depth of 15- 24 meter, from locations on the coastline of Island Kish in Persian Gulf of Iran. For identifying natural components, methanolic and diethyletter were used as extraction solvents, after removal of the solvents, the GC/MS spectra of the fraction were obtained. Then in vitro cytotoxic, antimicrobial and antifungal were identified. In vitro cytotoxity screening, by XTT assay, against KB/ C359 and HUT-56/ C365 cell line, was conducted in this study in 1 - 544 μg/ml. IC54 for winter diethyletter extract was 325 μg/ml, winter methanolic extract was 364 μg/ml, IC54 for summer diethyletter extract was 544 μg/ml, and summer methanolic extract was 454 μg/ml in HUT-56. IC54 for winter diethyletter extract was 454 μg/ml, winter methanolic extract was 444 μg/ml, IC54 for summer diethyletter extract was 344 μg/ml, and summer methanolic extract was 424 μg/ml in KB. In vitro antimicrobial activity by Broth Dilution Methods against clinical gram-positives and gram negatives (Escherichia coli, Pseudomonas aeruginosa, Staphylococcus aureus and Bacillus subtilis). The results conducted that the MIC values of winter diethyletter extract for Escherichia coli 24mg/ml, the MIC values of winter diethyletter extract for Escherichia coli 24mg/ml, the MIC and MBC values of winter diethyletter extract for Staphylococcus aureus was 2mg/ml and 24mg/ml. The MIC and MBC values of winter diethyletter extract for Bacillus subtilis was 1.5 mg/ml and 2mg/ml. In vitro antifungal activity by Broth Dilution Methods against clinical pathogens; Candida albicans and Aspergillus fumigatus. The results conducted that the aqueous extracts didn’t have any antifungal activities on pathogens, the MFC of the summer and winter diethyletter extract was 30 mg/ml and 2 mg/ml A. fumigates, the summer and winter methanolic extract was 0722 mg/ml and 2 mg/ml A. fumigates, the summer and winter methanolic was 4/75mg/ml, MFC 5 mg/ml on C. albicans.