Ce travail rapporte la synthèse et l'évaluation biologique des molécules hybrides de type isocombrétastatine A-4/belinostat. L'évaluation biologique de cette nouvelle série nous a permis d'identifier deux molécules inhibitrices de la polymérisation de la tubuline ainsi que de la HDAC8 possédant une puissante activité anti-proliférative dans la gamme du nanomolaire. De plus, nous démontrons que le système de catalyseur PtO2/PTSA-MeOH/H2O est très efficace pour convertir les alcynes internes et terminaux en cétones et qu’il est compatible avec une grande variété de groupes fonctionnels. / In this work, we report the synthesis and biological evaluation of isocombretastatin A-4/belinostat hybrid molecules. The biological evaluation of these new series has identified two molecules with potent anti-proliferative activity in the nanomolar range, which exhibit inhibitory activity on tubulin assembly and HDAC8. Second, we demonstrate that the PtO2/PTSA-MeOH/H2O catalyst system is very efficient in converting internal and terminal alkynes to ketones and that it is compatible with a wide variety of functional groups.

Zinc-binding proteins represent approximately one tenth of the proteome and a good portion of them are zinc-dependent hydrolases. This thesis focuses on biochemical and structural characterization of glutamate carboxypeptidase II (GCPII) and histone deacetylase 6 (HDAC6), two members of the zinc-dependent metallohydrolase superfamily. We describe here their interactions with natural substrates and inhibitors. GCPII is a homodimeric membrane protease catalyzing hydrolytic cleavage of glutamate from the neurotransmitter N-acetylaspartylglutamate (NAAG) and dietary folates in the central and peripheral nervous systems and small intestine, respectively. This enzyme is associated with several neurological disorders and also presents an ideal target for imaging and treatment of prostate cancer. GCPII inhibitors typically consist of a zinc-binding group (ZBG) linked to an S1' docking moiety (a glutamate moiety or its isostere). As such, these compounds are highly hydrophilic molecules therefore unable to cross the blood-brain barrier and this hampers targeting GCPII to the central nervous system. Different approaches are adopted to alter the S1' docking moiety of the existing inhibitors. As a part of this thesis, we present different strategies relying on replacement of the canonical P1' glutamate residue...

Indiana University-Purdue University Indianapolis (IUPUI) / Friedreich’s Ataxia (FRDA) is a rare and poorly understood autosomal recessive disease caused by a pathological deficiency of the mitochondrial protein frataxin. Patients suffer neurodegeneration, ataxia, diabetes, and heart failure. In an effort to understand the mechanisms of heart failure in FRDA, we investigated the role of the protein modification acetylation, which is highly abundant on mitochondrial proteins and has been implicated in regulating intermediary metabolism. Using mouse models of FRDA, we found that cardiac frataxin deficiency causes progressive hyperacetylation of mitochondrial proteins which is correlated with loss of respiratory chain subunits and an altered mitochondrial redox state. Mitochondrial protein hyperacetylation could be reversed by the mitochondria-localized deacetylase SIRT3 in vitro, suggesting a defect in endogenous SIRT3 activity. Consistently, frataxin-deficient cardiac mitochondria showed significantly decreased rates of fatty acid oxidation and complete oxidation to carbon dioxide. However, the degree of protein hyperacetylation in FRDA could not be fully explained by SIRT3 loss. Our data suggested that intermediary metabolites and perhaps acetyl-CoA, which is required for protein acetylation, are accumulating in frataxin-deficient mitochondria. Upon testing the hypothesis that mitochondrial protein acetylation is non-enzymatic, we found that the minimal chemical conditions of the mitochondrial matrix are sufficient to cause widespread non-enzymatic protein acetylation in vitro. These data suggest that mitochondrial protein hyperacetylation in FRDA cardiomyopathy mediates progressive post-translational suppression of mitochondrial oxidative pathways which is caused by a combination of SIRT3 deficiency and, likely, an accumulation of unoxidized acetyl-CoA capable of initiating non-enzymatic protein acetylation. These findings provide novel insight into the mechanisms underlying a poorly understood and fatal cardiomyopathy and highlight a fundamental biochemical mechanism that had been previously overlooked in biological systems.

Indiana University-Purdue University Indianapolis (IUPUI) / Cytokines are extracellular proteins that mediate communication between cells. T helper cell subsets secrete specific cytokines that promote the development of inflammation. Naïve CD4+ T cells activated and primed in the presence of TGF-β and IL-4 predominantly secrete IL-9, a cytokine that acts as a growth factor for T cells and mast cells, and promotes allergic inflammation. The transcription factors downstream of TGF-β- and IL-4-induced signaling, and that are required for expression of IL-9, have not been previously examined. IL-4 signaling induces the expression of IRF4, a transcription factor required for the development of Th9 cells. IL-4 and the downstream-activated factor STAT6 also interfere with the expression of the transcription factors T-bet and Foxp3 that inhibit IL-9 production from Th9 cells. The TGF-β pathway induces the expression of PU.1, another transcription factor required for Th9 development. In the absence of PU.1 there is increased association of a subset of histone deacetylases to the Il9 promoter. In developing Th9 cells, PU.1 can bind to the Il9 promoter and recruit specific histone acetyltransferases, including Gcn5 to the Il9 gene. Gcn5 functionally contributes to Il9 expression as IL-9 production is diminished when Gcn5 expression is reduced, although other cytokines expressed by Th9 cells are not affected. While Gcn5 is not required for PU.1 or IRF4 binding to Il9, it is important for controlling histone acetylation at the Il9 gene promoter. Together these data define the STAT6-dependent transcription factor network in Th9 cells and the mechanism of PU.1-dependent IL-9 induction in Th9 cells and might indicate that targeting IL-9 regulation is a viable approach for treating inflammatory disease.

Non-Small Cell Lung Cancer (NSCLC), which accounts for 80% of all lung cancer cases, is associated with resistance to chemotherapy and poor prognosis. Exploitation of NSCLC-upregulated pathways that can either be targeted by novel therapeutics or used to improve the tumour-delivery of current chemotherapeutics are required. Among the matrix metalloproteinases (MMPs) that are essential for tumour development, MMP10 is a potential candidate as a therapeutic target based on its expression and contribution to NSCLC development. This research aims to explore the expression and functions of MMP10 in the tumour microenvironment of NSCLC and evaluate the potential of MMP10 as a target for therapeutic intervention. Herein, MMP10 expression at gene and protein levels were analysed in a panel of NSCLC cell lines using RT-PCR and Western blotting analysis. To determine MMP10 functional relevance, an in vitro angiogenesis assay using cell conditioned media was carried out. To identify specific peptide sequences for the design of prodrugs rationalised to be MMP10 activated, in vitro substrate cleavage studies were performed using a mass spectrometry approach to differentiate between MMP10 and the structurally similar MMP3. This study demonstrates that MMP10 is highly expressed in NSCLC and that high levels of MMP10 are associated with induction of angiogenesis, a crucial process supporting tumour growth. In addition to the achievement of having been able to differentiate between closely similar MMP3 and MMP10 through carefully monitoring the hydrolysis rate of compound 444259 (a known MMP substrate), data generated herein provides the basis for further studies to exploit MMP10 as a prodrug-activator. / Full text was made available at the end of the embargo period, 12th Dec 2019

New chimeric inhibitors targeting the epidermal growth factor (EGFR) and histone deacetylases (HDACs) were synthesized and tested for antineoplastic efficiency in solid cancer (prostate and hepatocellular carcinoma) and leukemia/lymphoma cell models. The most promising compounds, 3BrQuin-SAHA and 3ClQuin-SAHA, showed strong inhibition of tumor cell growth at one-digit micromolar concentrations with IC50 values similar to or lower than those of clinically established reference compounds SAHA and gefitinib. Target-specific EGFR and HDAC inhibition was demonstrated in cell-free kinase assays andWestern blot analyses, while unspecific cytotoxic effects could not be observed in LDH release measurements. Proapoptotic formation of reactive oxygen species and caspase-3 activity induction in PCa and HCC cell lines DU145 and Hep-G2 seem to be further aspects of the modes of action. Antiangiogenic potency was recognized after applying the chimeric inhibitors on strongly vascularized chorioallantoic membranes of fertilized chicken eggs (CAM assay). The novel combination of two drug pharmacophores against the EGFR and HDACs in one single molecule was shown to have pronounced antineoplastic effects on tumor growth in both solid and leukemia/lymphoma cell models. The promising results merit further investigations to further decipher the underlying modes of action of the novel chimeric inhibitors and their suitability for new clinical approaches in tumor treatment.

<p>We showed previously that histone deacetylase (HDAC) inhibition with MS-275 in the context of boosting oncolytic immunotherapy can drive heightened antitumor responses, leading to increased survival in mouse intracranial melanoma models. However, it is currently unclear how the co-administration of MS-275 directly impacts tumor growth. Here, we investigated the role of MS-275 in preventing the outgrowth of antigen-deficient tumor variants as a result of suboptimal treatment protocols. By adoptively transferring tumor antigen-specific memory T cells (Tm) that were expanded <em>in vivo</em> with recombinant Vesicular Stomatitis Virus (VSV-gp33), we observed complete regression of 5-day old, intradermal B16-gp33 tumors (B16-F10 overexpressing the LCMV GP33-41 epitope); however, the tumors relapsed within a month of treatment. Relapsing tumor explants were able to grow in mice that were prophylactically immunized with recombinant Adenovirus (Ad-gp33), indicating that the tumor could no longer be recognized. Strikingly however, there was zero tumor recurrence if MS-275 was co-administered with Tm and VSV-gp33, suggesting that MS-275 may prevent the emergence and/or escape of antigen loss variants. Such a benefit is lost if the administration of the drug is delayed as little as five days post VSV treatment, suggesting that its synergistic effects coincide with early immune responses and oncolytic activity. Furthermore, transplantation studies of relapsing tumor explants showed that combination treatment was unable to provide tumor protection, confirming that the mechanisms by which MS-275 prevents tumor recurrence are unlikely through direct up-regulation of antigen presentation in low- or non-antigen-expressing variants <em>in vivo</em>. Indeed, CD4 depletion in the absence of MS-275 resulted in sustained tumor regression, implying that immunoregulatory cells such as CD4+ Treg play a prominent role in sustaining tumor regression. Moreover, MS-275 modulates the phenotypic status of tumor-infiltrating MDSCs toward the differentiation of inflammatory macrophages. Taken together, the data suggests that combination therapy with HDACi with oncolytic immunotherapy mediates a synergized immune attack against the tumor through subversion of immunomodulatory mechanisms.</p> / Master of Science in Medical Sciences (MSMS)

Au cours des maladies cardiovasculaires (MCV), il peut se produire divers problèmes de santé, telle que l’insuffisance cardiaque ou encore l’HTA. Ces phénomènes se caractérisent, entre autres, par une augmentation de synthèse d’endotheline-1 (ET-1), un neuropeptide synthétisé par les cellules endothéliales ayant un effet vasoconstricteur sur les cellules musculaires lisses vasculaires (CMLV). Ainsi, la surexpression de ce vasopeptide, mène à terme, au maintien de l’HTA aggravée des sujets, précédée ou concomitante à l’athérosclérose ou à la resténose, cliniquement illustrées par une prolifération et une migration anormale des CMLV de la media vers l’intima des vaisseaux sanguins. Parallèlement, il a été observé que la protéine sirtuine-1 (Sirt-1), membre de la famille des protéines histones déacétylases (HDAC), présente des propriétés anti-athérosclérotiques par sa capacité d’atténuer la prolifération et la migration des CMLV. Des travaux récents ont aussi montré qu’au cours de l’HTA la protéine Sirt-1 est faiblement exprimée dans les CMLV. Son implication dans le développement des pathologies vasculaires semble apparente, mais des études demeurent nécessaires pour décrire son rôle exact dans la pathogenèse des MCV. Dans cette optique, l’objectif de cette étude a été d’observer la variation d’expression de Sirt-1 dans les CMLV, isolées de l’aorte ascendante de rat, en réponse à l’ET-1. On a remarqué qu’une heure de stimulation des CMLV avec l’ET-1 induit une diminution de l’expression de Sirt-1 via l’activation des récepteurs ETA. Ces résultats suggèrent que la capacité d’ET-1 à atténuer l’expression de Sirt-1 serait un éventuel mécanisme d’action avec des effets favorisant les MCV. / Cardiovascular diseases (CVD) are associated with several vascular dysfunctions such as heart failure and hypertension. These phenomena cause increased synthesis of endothelin-1 (ET-1), a neuropeptide, synthesized by endothelial cells which has vasoconstrictor action on vascular smooth muscle cells (VSMC). Overexpression of this vasopeptide leads eventually to hypertension (HTA). This usually happen after atherosclerosis or restenosis, leading to proliferation and migration of VSMC from media to intima. It was shown that during atherosclerosis, the protein sirtuin-1 (Sirt-1), a member of protein histone deacetylases (HDAC), has an anti-atherosclerotic effect due to its ability to diminish proliferation and migration of VSMC. It has also been observed that during hypertension, Sirt-1 was poorly expressed in VSMC. Its role in vascular pathophysiology remains sparsely studied, therefore it’s essential to explore it. In the present study we investigated the expression of Sirt-1 in VSMC isolated from the ascending aorta of rats, in response to ET-1 stimulation. We observed that Sirt-1 expression decreases after 1 hour of stimulation by ET-1 via ETA receptors. In summary, these results suggest that the ability of ET-1 to attenuate Sirt-1 expression in VSMC, may be a potential mechanism for promoting CVD.

La sénescence cellulaire, ou l’arrêt irréversible de la prolifération, influence des processus physiologiques et pathologiques, comme le cancer. Parmi les caractéristiques de la sénescence, se retrouve le PSAS ou phénotype sécrétoire associé à la sénescence. Le PSAS est composé d’une variété de cytokines, facteurs de croissance et protéases. Ses actions pro- et anti-tumorale sont connues, mais l’on ignore laquelle prédomine. Mes travaux s’attardent aux effets du PSAS sur l’induction de la sénescence dans les cellules environnantes et à sa régulation. Nous avons démontré que le PSAS ne synergise pas avec la dysfonction télomérique chronique ou aigue, afin de causer un arrêt de croissance. Également, l’étude du mécanisme responsable de l’induction de la sénescence par stress à la chromatine, suggère que la kinase c-Abl n’est pas requise pour cette voie, contrairement à des publications antérieures. Mes travaux éclairent les mécanismes d’action et la régulation du PSAS dans la sénescence induite par dysfonction télomérique et par stress à la chromatine. / Cellular senescence, or irreversible proliferation arrest, is known for its influence on physiological and pathological processes, such as cancer. Among the features found in the senescent phenotype is the inflammatory secretome, also known as the senescence associated secretory phenotype (SASP). The SASP consists of a variety of factors such as cytokines, growth factors and proteases. It is widely recognized that SASP can have either a pro- or anti-tumor effect, but it is not clear which one predominates. My work focused on the SASP effects on the induction of senescence in surrounding cells and its regulation mechanisms. We demonstrated that the SASP does not synergize with chronic or induced telomere dysfunction to cause cellular proliferation arrest. Also, study of chromatin stress-induced senescence mechanism suggests that kinase c-Abl is not required for this pathway, contrary to what had been previously published. My work helps understand the regulatory and working mechanisms of the SASP in chromatin stress-induced and telomere dysfunction-induced senescence models.

Pubertal timing displays wide, normally distributed variation in a healthy population of sexually maturing adolescents. However, like many complex traits, factors contributing to the variation are not well understood. Epigenetic regulation may contribute to some of the population variation. The role that epigenetics, specifically DNA methylation and histone acetylation, may play in regulating pubertal timing was investigated in C57BL/6 female mice: investigating whether population variation in pubertal timing among inbred mice could be explained by environmental factors; whether perturbing the epigenome using a histone deacetylase inhibitor or methyl-donor would alter pubertal timing; and examining genome-wide methylation patterns in hypothalami of early versus late maturing mice. Results demonstrate that measurable micro-environmental factors have only negligible effects on pubertal timing; pubertal timing was significantly altered by administration of epigenetic modifying agents; differences in methylation patterns are subtle. This initial evidence supports the involvement of epigenetic mechanisms in regulating pubertal timing.