L'inhibidor de carboxipeptidasa de patata (PCI) és un antagonista de l'EGF. Un dels problemes del PCI, però, és la baixa afinitat per l'EGFR en comparació amb el lligand natural. En aquest treball s'han dissenyat nous bloquejadors de la via ErbB partint de l'estructura de l'EGF per tal d'augmentar l'afinitat d'unió. S'ha determinat que les variants tenen reduïda la capacitat d'activació del receptor però segueixen promovent la proliferació cel·lular. Tot i així, s'ha obtingut una variant, l'EGF Truncat, que tot i no estar correctament plegada, és la que ofereix uns millors. També s'ha dut a terme un tractament combinat entre el PCI i un inhibidor de tirosin quinases d'aquesta mateixa via, l'Iressa. Els resultats han posat de manifest que hi ha un antagonisme entre els dos tractaments. Aquesta és la primera vegada que s'associa de forma directa un tipus de tractament amb una resistència associada a l'activació de la producció autocrina de lligands, i representa un avenç molt important en la recerca oncològica. / Potato carboxypeptidase inhibitor (PCI) is an EGF antagonist. One of the main problems of PCI is its low affinity for EGFR in comparison to the natural ligand. In this study, blockers of the ErbB pathway have been designed taking as a model the EGF structure, in order to increase binding affinity. It has been observed that the variants have less ability to activate the receptor but they still promote cell proliferation. Nevertheless, the variant called Truncated EGF, although being unfolded, is the one that shows best perspectives.A combined treatment using PCI and a tyrosine kinase inhibitor of the same pathway, Iressa, has also been carried out. Results have shown that there is an antagonism between both treatments. This is the first time that a treatment is associated to resistance involving autocrine loop activation of ligands, and it represents a very important finding in the oncologic research.

Les cancers hépatiques, bronchiques et mammaires sont responsables de 35 % de décès par le cancer en 2012. Les études sur des facteurs contribuant à la progression tumorale devraient approfondir nos connaissances sur la biologie de ces cancers et ouvrir de nouvelles voies pour le développement de stratégies thérapeutiques. Dans ce contexte, nous avons étudié l'impact de la neurotensine (NTS) et de son récepteur NTSR1 sur la progression tumorale et son rôle potentiel pour de futures applications cliniques. J’ai initié ce projet dans le carcinome hépatocellulaire (CHC) et participé aux projets dans le cancer du poumon et du sein qui avaient été initiés par les anciens doctorants de l’équipe. Dans le CHC, sur une série de 73 patients, la NTS et le NTSR1 ont été détectés dans respectivement 56 % et 64 % des cas. En utilisant deux modèles cellulaires nous avons montré que l’expression du NTSR1 est une cible de la voie wnt/β-caténine. Le couple NTS/NTSR1 augmente l’expression et l’activation de l’EGFR et favorise la croissance des tumeurs expérimentales et la capacité de migration et d’invasion des cellules. La régulation entre le complexe NTS/NTSR1 et les récepteurs des HERs a également été observée dans les cancers bronchiques et mammaires, la NTS induit l'expression et l'activation constitutive des récepteurs EGFR, HER2 et HER3, par l'intermédiaire de l'activation des métalloprotéinases qui libèrent les ligands “EGF-like” spécifiques d'EGFR et d’HER3. L’activation constitutive des HER par le couple NTS/NTSR1 mime les mutations activatrices des HERs, ainsi la réponse des tumeurs aux inhibiteurs de tyrosine kinase est potentialisée dans le cancer du poumon, du sein et du foie. / In 2012, Liver, lung and breast cancers represented 30% of new cancer cases, and 35% of cancer related deaths. Identification of factors contributing to tumor progression can strengthen our understanding of the cancer biology and suggest new therapeutic strategies. In this context, we studied the impact of neurotensin (NTS) and its receptor NTSR1 on tumor progression and its potential clinical application. I have initiated the project in hepatocellular carcinoma (HCC) and participated in the projects on lung and breast cancers initiated by former PhD students. In HCC, on a series of 73 patients, NTS and NTSR1 were detected in 56% and 64% of the cases, respectively. Meanwhile, I showed that NTSR1 expression is the target of the Wnt/¦Â-catenin pathway. The NTS / NTSR1 complex increases the expression and activation of EGFR and promotes the growth of experimental tumors and the ability of the cell for migration and invasion. The regulation between the NTS/NTSR1 complex and EGF receptors were also thoroughly studied in lung and mammary cancers. Indeed, NTS induced the expression and the constitutive activation of EGFR, HER2, and HER3, through the activation of metalloproteinases which released specific "EGF-like" ligands for EGFR and HER3. Constitutive activation of HERs by the NTS/NTSR1 complex mimics the activating mutations of HERs and therefore potentiates the tumor response to tyrosine kinase inhibitors treatment in liver, lung and breast cancers.

Tumorigenesis is a multistep process, during which cells acquire a series of mutations that lead to unrestrained cell growth and proliferation, inhibition of cell differentiation, and evasion of cell death. Growing tumors stimulate angiogenesis, providing them with nutrients and oxygen. Ultimately, tumor cells invade the surrounding tissue and metastasize; a process responsible for about 90% of cancer-related deaths. Adhesion G protein-coupled receptors (aGPCRs) modulate the cellular processes closely related to tumor cell biology, such as adhesion and detachment, migration, polarity, and guidance. Soon after first being described, individual human aGPCRs were found to be involved in tumorigenesis. Twenty-five years ago, CD97/ADGRE5 was discovered to be induced in one of the most severe tumors, dedifferentiated anaplastic thyroid carcinoma. After decades of research, the time has come to review our knowledge of the presence and function of CD97 in cancer. In summary, CD97 is obviously induced or altered in many tumor entities; this has been shown consistently in nearly one hundred published studies. However, its high expression at circulating and tumor-infiltrating immune cells renders the systemic targeting of CD97 in tumors difficult.

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No description available.

Les cellules stromales mésenchymateuses (CSM) possèdent de nombreux atouts pour la thérapie cellulaire du cerveau. Nous avons tout d'abord démontré que les CSM ne migraient pas dans le cerveau de rats sains alors qu'elles étaient attirées par une lésion située à grande distance de leur site d'implantation. Nous avons également confirmé que la faible survie et différenciation neuronale des cellules in vivo constituent les obstacles majeurs à la thérapie cellulaire du cerveau. Par conséquent, nous nous sommes ensuite attachés à améliorer le potentiel de différenciation neuronal des CSM avant transplantation, à l'aide d'un pré-traitement en « epidermal growth factor » (EGF) et « basic fibroblast growth factor » (bFGF) in vitro. Finalement, nous avons associé des CSM à des vecteurs polymériques, les microcarriers pharmacologiquement actifs (MPA), afin de favoriser la survie, la différenciation neuronale et les capacités de réparation tissulaire des cellules après transplantation. Ces microsphères de PLGA ont ainsi été enrobées d'une surface biomimétique de laminine, après en avoir démontré les bénéfices sur la différenciation neuronale des CSM in vitro. Des CSM ont ensuite été mises en contact avec des MPA enrobées de laminine et libérant une neurotrophine, avant transplantation dans un modèle animal de la maladie de Parkinson. D'importants effets fonctionnels ont été observés par rapport à la greffe de cellules seules, et cette stratégie est la première à démontrer l'intérêt de cellules souches adultes associées à des vecteurs polymériques bioactifs pour protéger le système nerveux central dans le contexte de la maladie de Parkinson.

<p>Thyroid growth and function is partly regulated by growth factors binding to receptors on the cell surface. In the present thesis, the transforming growth factor-β (TGF-β) superfamily members have been studied for their role in regulation of growth and differentiation of both normal and neoplastic thyroid epithelial cells.</p><p>TGF-β1 is a negative regulator of thyrocyte growth and function. However, the importance of other TGF-β superfamily members has not been fully investigated. TGF-β1, activin A, bone morphogenetic protein (BMP)-7 and their receptors were found to be expressed in porcine thyrocytes. In addition to TGF-β1, activin A was also found to be a negative regulator of thyroid growth and function, and both stimulated phosphorylation and nuclear translocation of Smad proteins. Furthermore, TGF-β1 and epidermal growth factor (EGF) demonstrated a synergistic negative effect on thyrocyte differentiation. Simultaneous addition of the two factors resulted in a loss of the transepithelial resistance and expression of the epithelial marker E-cadherin. This was followed by a transient expression of N-cadherin.</p><p>Despite the extremely malignant character of anaplastic thyroid carcinoma (ATC) tumor cells, established cell lines are still responsive to TGF-β1. A majority of the cell lines were also found to be growth inhibited by BMP-7. BMP-7 induced cell cycle arrest of the ATC cell line HTh 74 in a dose- and cell density-dependent manner. This was associated with upregulation of p21^CIP1 and p27^KIP1, decreased cyclin-dependent kinase (Cdk) activity and hypophosphorylation of the retinoblastoma protein (pRb). TGF-β1, and to some extent also BMP-7, induced the expression of N-cadherin and matrix metalloproteinase (MMP)-2 and -9. Stimulation of HTh 74 cells with TGF-β1 increased the migration through a reconstituted basement membrane indicating an increased invasive phenotype of the cells.</p><p>Taken together, these data show that TGF-β superfamily members not only affect growth and function of normal thyroid follicle cells but may also, in combination with EGF, play a role in cell dedifferentiation. This study additionally suggests that the TGF-β superfamily members may be important for the invasive properties of ATC cells.</p>

<p>Physico-chemical characterisation of structure and stability of liposomes intended for drug delivery is the central issue in this thesis. In addition, targeted liposomes to be used in boron neutron capture therapy (BNCT) were developed.</p><p>Lysolipids and fatty acids are products formed upon hydrolysis of PC-lipids. The aggregate structure formed upon mixing lysolipids, fatty acids and EPC were characterised by means of cryo-TEM. A relatively monodisperse population of unilamellar liposomes was detected in mixtures containing equimolar concentration of the three components. </p><p>The interactions between alternative steric stabilisers (PEO-PPO-PEO copolymers) and conventional PC-and pH-sensitive PE-liposomes were investigated. Whereas the PE-liposomes could be stabilised by the PEO-PPO-PEO copolymers, the PC-liposomes showed an enhanced permeability concomitant with the PEO-PPO-PEO adsorption.</p><p>Permeability effects induced by different PEG-stabilisers on EPC liposomes were shown to be dependent on the length of the PEG chain but also on the linkage used to connect the PEG polymer with the hydrophobic membrane anchor.</p><p>An efficient drug delivery requires, in most cases, an accumulation of the drug in the cell cytoplasm. The mechanism behind cytosolic drug delivery from pH-sensitive liposomes was investigated. The results suggest that a destabilisation of the endosome membrane, due to an incorporation of non-lamellar forming lipids, may allow the drug to be released. </p><p>Furthermore, sterically stabilised liposomes intended for targeted BNCT have been characterised and optimised concerning loading and retention of boronated drugs. </p>

Thyroid growth and function is partly regulated by growth factors binding to receptors on the cell surface. In the present thesis, the transforming growth factor-β (TGF-β) superfamily members have been studied for their role in regulation of growth and differentiation of both normal and neoplastic thyroid epithelial cells. TGF-β1 is a negative regulator of thyrocyte growth and function. However, the importance of other TGF-β superfamily members has not been fully investigated. TGF-β1, activin A, bone morphogenetic protein (BMP)-7 and their receptors were found to be expressed in porcine thyrocytes. In addition to TGF-β1, activin A was also found to be a negative regulator of thyroid growth and function, and both stimulated phosphorylation and nuclear translocation of Smad proteins. Furthermore, TGF-β1 and epidermal growth factor (EGF) demonstrated a synergistic negative effect on thyrocyte differentiation. Simultaneous addition of the two factors resulted in a loss of the transepithelial resistance and expression of the epithelial marker E-cadherin. This was followed by a transient expression of N-cadherin. Despite the extremely malignant character of anaplastic thyroid carcinoma (ATC) tumor cells, established cell lines are still responsive to TGF-β1. A majority of the cell lines were also found to be growth inhibited by BMP-7. BMP-7 induced cell cycle arrest of the ATC cell line HTh 74 in a dose- and cell density-dependent manner. This was associated with upregulation of p21CIP1 and p27KIP1, decreased cyclin-dependent kinase (Cdk) activity and hypophosphorylation of the retinoblastoma protein (pRb). TGF-β1, and to some extent also BMP-7, induced the expression of N-cadherin and matrix metalloproteinase (MMP)-2 and -9. Stimulation of HTh 74 cells with TGF-β1 increased the migration through a reconstituted basement membrane indicating an increased invasive phenotype of the cells. Taken together, these data show that TGF-β superfamily members not only affect growth and function of normal thyroid follicle cells but may also, in combination with EGF, play a role in cell dedifferentiation. This study additionally suggests that the TGF-β superfamily members may be important for the invasive properties of ATC cells.

Physico-chemical characterisation of structure and stability of liposomes intended for drug delivery is the central issue in this thesis. In addition, targeted liposomes to be used in boron neutron capture therapy (BNCT) were developed. Lysolipids and fatty acids are products formed upon hydrolysis of PC-lipids. The aggregate structure formed upon mixing lysolipids, fatty acids and EPC were characterised by means of cryo-TEM. A relatively monodisperse population of unilamellar liposomes was detected in mixtures containing equimolar concentration of the three components. The interactions between alternative steric stabilisers (PEO-PPO-PEO copolymers) and conventional PC-and pH-sensitive PE-liposomes were investigated. Whereas the PE-liposomes could be stabilised by the PEO-PPO-PEO copolymers, the PC-liposomes showed an enhanced permeability concomitant with the PEO-PPO-PEO adsorption. Permeability effects induced by different PEG-stabilisers on EPC liposomes were shown to be dependent on the length of the PEG chain but also on the linkage used to connect the PEG polymer with the hydrophobic membrane anchor. An efficient drug delivery requires, in most cases, an accumulation of the drug in the cell cytoplasm. The mechanism behind cytosolic drug delivery from pH-sensitive liposomes was investigated. The results suggest that a destabilisation of the endosome membrane, due to an incorporation of non-lamellar forming lipids, may allow the drug to be released. Furthermore, sterically stabilised liposomes intended for targeted BNCT have been characterised and optimised concerning loading and retention of boronated drugs.