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No. of bitstreams: 2 Dissertação - Thiago David Alves Pinto - 2017.pdf: 3530254 bytes, checksum: c69d231fc95105583f213b9560d72667 (MD5) license_rdf: 0 bytes, checksum: d41d8cd98f00b204e9800998ecf8427e (MD5) Previous issue date: 2017-05-19 / Epidermal growth factor receptor inhibitors represent a treatment option with proven efficacy for patients with metastatic colorectal carcinoma. However, patients with activating mutations in KRAS and NRAS have no response. Currently, wild KRAS and NRAS are prerequisite for this therapy. Furthermore, mutation tests are expensive and not easily accessible. EGFR expression by immunohistochemistry predicting the expanded RAS mutation (KRAS and NRAS), may allow the treatment to be instituted through a less costly and more accessible diagnostic method. The objective of this study is to test the correlation between EGFR cytoplasmic-membrane expression and the mutational status of the expanded RAS in colorectal carcinomas. An accuracy analysis was performed on 139 patients with colorectal carcinoma selected from the archives of the Instituto Goiano de Oncologia e Hematologia. The correlation between clinical-pathological data, the mutational state of the expanded RAS and the pattern of EGFR cytoplasmic-membrane expression were investigated. The expanded RAS mutation was detected in 78 (56.1%) cases. EGFR expression was stratified into 23 (16.5%) "Positives", 49 (35.2%) "Negatives" and 67 (48.2%) "Uncertain" cases. There was no significant association between age (p = 0.541 and 0.652), sex (p = 0.388 and 0.540), location (p = 0.393 and 0.098), histological type (p = 0.199 and 0.697), histological grade (p = 0.900 and 0.182) and stage (p = 0.533 and 0.053). The expression of EGFR stratified in "Positives", "Negatives" and "Uncertain" compared to the mutational status of the expanded RAS showed a strong association between the groups (p <0.001). Of the 23 "Positive" cases, 21 (91.3%) showed wild RAS gene. Of the 49 "Negative" cases, 41 (83.7%) presented mutation in the expanded RAS panel. Therefore, our study is pioneer in revealing that the EGFR cytoplasmic-membrane analysis, stratified in "Positives," "Negatives" and "Uncertain", predicts the mutational state of RAS in 51.7% of cases (p <0.001), with 86.1% accuracy. However further studies are needed to determine why nearly half of the cases are still doubtful. More complete analyzes contemplating the amplification of EGFR and mutations in other EGFR / MAPK cascade genes such as BRAF and PIK3CA, could enable a better stratification of the population. / Inibidores do receptor do fator de crescimento epidérmico representam uma opção terapêutica com eficácia comprovada para pacientes com carcinoma colorretal metastático. Porém, pacientes com mutações ativadoras em KRAS e NRAS não apresentam resposta. Atualmente, KRAS e NRAS selvagens são pré-requisito para esta terapêutica. Entretanto, a pesquisa de mutações é de alto custo e pouco acessível. A expressão do EGFR por imuno-histoquímica predizendo a mutação expandida do RAS (KRAS e NRAS) pode permitir que o tratamento seja instituído através de um método diagnóstico menos oneroso e mais acessível. O objetivo desse estudo é testar a correlação entre a expressão do EGFR e o estado mutacional do RAS expandido em carcinomas colorretais. Foi realizada uma análise de acurácia em 139 pacientes com carcinoma colorretal selecionados dos arquivos do Instituto Goiano de Oncologia e Hematologia. Foram pesquisados a correlação entre dados clínico-patológicos, estado mutacional do RAS expandido e padrão de expressão membrano-citoplasmática do EGFR. A mutação do RAS expandido foi detectada em 78 (56,1%) casos. A expressão do EGFR foi estratificada em 23 (16,5%) casos “Positivos”, 49 (35,2%) “Negativos” e 67 (48,2%) “Duvidosos”. Não foi identificada associação significativa em comparação a idade (p=0,541 e 0,652), sexo (p=0,348 e 0,540), localização (p=0,393 e 0,098), tipo histológico (p=0,199 e 0,697), grau histológico (p=0,900 e 0,182) e estadio (p=0,533 e 0,053). A expressão do EGFR estratificada em “Positivos”, “Negativos” e “Duvidosos” em comparação ao estado mutacional do RAS expandido mostrou forte associação entre os grupos (p<0,001). Dos 23 casos “Positivos”, 21 (91,3%) mostraram gene RAS selvagem. Dos 49 casos “Negativos”, 41 (83,7%) apresentaram mutação no painel RAS expandido. Portanto, nosso estudo é pioneiro em revelar que a análise membrano-citoplasmatica do EGFR estratificada em “Positivos”, “Negativos” e “Duvidosos” prediz o estado mutacional do RAS em 51,7% dos casos (p<0,001), com 86,1% de acurácia. Entretanto, novos estudos são necessários para determinar a razão de quase metade dos casos ser ainda duvidosa. Análises mais completas, contemplando a amplificação do EGFR e mutações em outros genes da cascata EGFR/MAPK como BRAF e PIK3CA podem possibilitar uma melhor estratificação desta população.

Abstract Basement membranes (BM) underlie epithelia and endothelia and surround many tissues. In cutaneous BM epithelial cells are attached to the stroma via multiprotein complexes called hemidesmosomes (HD). Collagen XVII and integrin α6β4 are components of HD and they bind to laminin 332, a component of anchoring filaments, extracellularly. The main interest of this study is the function of collagen XVII and its interactions with these proteins. What is known about the function of collagen XVII is mostly derived from its role as an adhesive component in cutaneous HD. Here we demonstrate for the first time that collagen XVII is expressed by podocytes in the human and murine glomerulus and that mutant mice lacking collagen XVII in addition to small size, blisters and diffuse hair loss, also have deficient glomerular development and a high mortality rate. We also show for the first time at the protein level that collagen XVII is expressed, and probably has a functional interaction with laminin 332, in normal colon epithelia. We demonstrate that collagen XVII is expressed by the invasive cells of human colorectal carcinoma (CRC) samples and its immunostaining is increased in metastasis in CRC. The higher proportion of collagen XVII positive tumor cells correlates with decreased disease-free survival and cancer-specific survival times and we also suggest a functional interaction between collagen XVII and laminin 332 in CRC. Previous studies have suggested that collagen XVII participates in keratinocyte migration by affecting the correlation of HD disassembly and assembly, its expression is increased in squamous cell carcinoma (SCC) and it may have a role in cell adhesion and migration in SCC carcinogenesis. Here we demonstrate upregulated collagen XVII, integrin β4 and laminin γ2 expression in actinic keratosis, Bowen’s disease and SCC. The expression of collagen XVII was increased with a high degree of variation, especially in samples taken from areas where SCC is particularly invasive. We also demonstrate in the SCC-25 cell line that lack of collagen XVII or integrin β4 severely disrupts the adhesion, migration and invasivity of these cells. Taken together, in this study we show that collagen XVII is needed for normal glomerular development, is expressed in normal colon epithelia and participates in CRC and SCC carcinogenesis together with laminin 332 and integrin β4. / Tiivistelmä Tyvikalvot sijaitsevat epiteelin ja endoteelin alla ja ympäröivät monia kudoksia. Ihon tyvikalvossa epiteelisoluja alla olevaan verinahkaan kiinnittää rakenne, jota kutsutaan hemidesmosomiksi (HD). Kollageeni XVII ja integriin α6β4 ovat HD:n rakenneproteiineja. Ne kiinnittyvät solun ulkopuolella laminiin 332 nimiseen proteiiniin, joka muodostaa ankkurifilamentit. Kollageeni XVII ilmentyminen ja toiminta yhdessä näiden kahden proteiinin kanssa on tämän tutkimuksen keskeisin kohde. Valtaosa tutkimuksista, jotka käsittelevät kollageeni XVII:ää, koskevat sen toimintaa ihon keratinosyyteissä. Tässä tutkimuksessa osoitimme ensi kertaa, että hiiren ja ihmisen munuaiskerästen podosyyttisolut ilmentävät kollageeni XVII. Geenimanipuloidut hiiret, joilta kollageeni XVII oli poistettu, olivat pieniä, kehittivät rakkuloita ja karvattomuutta, niillä oli korkea kuolleisuus ja niiden munuaiskerästen kehitys oli häiriintynyt. Kollageeni XVII esiintymistä proteiinitasolla, sekä mahdollista toiminnallista yhteyttä laminiin 332:een, ei aiemmin ole osoitettu paksusuolen epiteelissä. Havaitsimme, että paksu- ja peräsuolen adenokarsinooman (CRC) invasiivinen solukko ilmentää kollageeni XVII:ää, kollageeni XVII esiintyminen on merkittävän voimakasta CRC:n metastasoinnin yhteydessä ja lisääntynyt kollageeni XVII esiintyminen lyhentää syöpävapaata aikaa ja heikentää syöpäspesifistä selviytymistä. Myös CRC:ssä kollageeni XVII toiminta voi liittyä laminiini 332:een. Aiempien tutkimusten mukaan kollageeni XVII osallistuu keratinosyyttien migratioon vaikuttamalla toimivien HD:ien määrään. Sen määrän on havaittu olevan korkeampi okasolusyövässä (SCC) ja sen on ehdotettu osallistuvan syöpäsolujen adheesioon ja migraatioon SCC:n kehittyessä. Me osoitimme kohonneen kollageeni XVII, integriini β4 ja laminiini γ2 ilmenemisen aktiinisessa keratoosissa, Bowenin taudissa sekä SCC:ssä. Kollageeni XVII määrä oli korkea, mutta vaihteli paljon, sekä hiiren että ihmisen invasiivisilla SCC alueilla. Havaitsimme myös SCC-25 solulinjalla, että kollageeni XVII tai integriini β4 puutos häiritsee vakavasti solujen adheesiota, migraatiota ja invaasiota. Yhteenvetona tässä työssä osoitimme, että kollageeni XVII:ää tarvitaan munuaiskerästen kehittymisessä, sitä esiintyy paksusuolen epiteelissä, ja että kollageeni XVII osallistuu CRC:n ja SCC:n kehittymiseen yhdessä integriini β4:n ja laminiini 332:n kanssa.

In der vorliegenden Arbeit werden mit den Jahren 2005/2006 und 2007 qualitätsrelevante Parameter von Patienten mit einem kolorektalen Karzinom vor und unmittelbar nach Gründung des Darmzentrums an der Universitätsklinik Leipzig analysiert. Ziel dieser Arbeit war es zu untersuchen, welchen Einfluss die Gründung eines zertifizierten Darmzentrums kurzfristig auf die Behandlungsqualität von Patienten mit einem kolorektalen Karzinom hat. Die durch die Deutsche Krebsgesellschaft festgelegten Struktur- bzw. Ergebnisparameter wurden für die Jahre 2005 und 2006 retrospektiv - ab 2007 kontinuierlich erfasst. Die meisten, aber nicht alle Anforderungen der Deutschen Krebsgesellschaft wurden erreicht, bzw. umgesetzt. So zeigte sich eine bessere Dokumentation der Behandlung, insbesondere in der Pathologie. Ausserdem konnte eine Zunahme der Fallzahlen verzeichnet werden. Die Ergebnisse der Arbeit zeigen, dass durch eine Zertifizierung als Darmzentrum zunächst eine Verbesserung der Dokumentation und Standardisierung der Therapie bewirkt werden kann. Kurzfristig kann in einigen, aber nicht allen Behandlungsparametern, eine Qualitätsverbesserung, insbesondere in der Chirurgie, erreicht werden.

La progression métastatique des cancers est responsable de 90% des décès liés à la maladie. Cette cascade est initiée par l’invasion des cellules cancéreuses du stroma péritumoral, et conduit à leur dissémination dans l’organisme.Mon travail de thèse a eu pour but d’identifier les mécanismes moléculaires et cellulaires régulant l’invasion des cancers colorectaux (CRC), qui est le 2ème cancer le plus répandu dans le monde. Grâce à une analyse réalisée sur des échantillons humains de tumeurs primaires, nous avons révélés que les cellules de CRC utilisent un mode d’invasion collective dans lequel elles gardent une architecture glandulaire spécifique des épithelia. Afin d’étudier les voies de signalisation régulant cette invasion, nous avons utilisé des modèles organotypiques récapitulant l’architecture des glandes de CRC (cystes de Caco-2 et tumoroïdes de xénogreffes derivés de patients) dans des tests d’invasion utilisant du collagen-I. Du fait de son rôle central dans la régulation de la motilité cellulaire, la voie des RhoGTPases était un bon candidat à la régulation de l’invasion collective des CRC. Dans un screen utilisant des siRNA ciblant tous les effecteurs connus des RhoGTPases, seule la déplétion des protéines kinases ROCK a déclenché l’invasion collective dans notre système expérimental. Nous avons démontré que l’inhibition de ROCK2 et non de ROCK1 était suffisante pour induire la formation de cellules leader, permettant la polarisation leader/follower requise pour l’invasion collective. Nos résultats montrent que l’inhibition de ROCK2 déclenche l’invasion collective par l’inhibition de MyosinII combinée à l’activation du facteur d’échange nucléotide guanine (GEF), FARP2, et de RAC1. Notre étude permet donc d’identifier FARP2 comme un nouvel effecteur de ROCK2 et le positionne comme un nouveau médiateur du crosstalk entre RhoA et RAC1 dans la régulation de l’invasion collective des CRC. En conclusion, nous avons décrit une nouvelle voie de signalisation dépendante de ROCK2 contrôlant l’invasion collective de glandes de CRC. De façon intéressante, notre étude révèle un rôle anti-invasive de ROCK2 contredisant son rôle pro-invasive décrit dans l’invasion de cellules individuelles. Cela suggère que ROCK2 assure des rôles distincts en fonction du mode d’invasion adopté par les cellules cancéreuses et remet en question le bénéfice thérapeutique de l’inhibition de ROCK proposé pour bloquer l’invasion des cellules cancéreuses. / Metastatic progression of cancer is responsible for 90% of the disease related death. It is a multi-step process which is initiated by invasion of the peritumoral stroma by cancer cells and which leads to the dissemination of cancer cells in the organism.My PhD work aimed at identifying the molecular and cellular process driving colorectal carcinoma (CRC) invasion, which is the 2nd most frequent cancer worldwide. Our analysis of live and human primary cancer specimen revealed that CRC cells used a collective mode of invasion to disseminate, in which cells retain an epithelium specific -glandular architecture. To investigate the signaling pathways regulating this mode of invasion, we used 3D organotypic models recapitulating the features of CRC glands (Caco-2 cysts and Patient derived Xenografts (PDX) tumoroids) in collagen-I based organotypic invasion assays and in microscopy-based analyses. Because of its central role in the regulation of cell motility, we postulated that RhoGTPases signaling pathways could control the collective of CRC. In a siRNA based- screen targeting all the known effectors of RhoGTPases we found that only ROCK kinases downregulation induced collective invasion in our experimental settings. We demonstrated that ROCK2 but not ROCK1 inhibition was sufficient to promote Leader cell formation, which induced the leader/follower polarization necessary for collective invasion. Our results revealed that ROCK2 inhibition triggered collective invasion through the concomitant inhibition of MyosinII and activation of the guanine nucleotide exchange factor (GEF) FARP2 and the RhoGTPase RAC1. We therefore identify FARP2 as a new effector of ROCK2 and a mediator of the RhoA-RAC1 crosstalk in the regulation of collective invasion. In conclusion our study proposes a new ROCK dependent-signaling pathway in the regulation of collective invasion of highly polarized CRC glands models. Importantly, we found ROCK2 to be an anti-invasive protein which is in contradiction with its described pro-invasive role in single cell invasion. This suggests distinct roles of ROCK which may depend on the mode of invasion adopted by the cells and questions the benefice of proposed ROCK inhibition strategies to block cancer cell invasion.

Lipoxygenases convert polyunsaturated fatty acids into biologically active metabolites such as inflammatory mediators—prostaglandins and leukotrienes. The inhibition of lipoxygenases is increasingly employed in the treatment of cancer. We evaluated the anticancer potential of two novel 5-lipoxygenase inhibitors, named CarbZDNaph and CarbZDChin, which are analogues of the commercially available inhibitor Rev-5901. The in vitro segment of this study was conducted on a mouse colorectal carcinoma cell line—CT26CL25. For an in vivo model, we induced tumors in BALB/c mice by the implantation of CT26CL25 cells, and we treated the animals with potential inhibitors. A 48 h treatment resulted in diminished cell viability. Calculated IC50 values (halfmaximal inhibitory concentrations) were 25 µM, 15 µM and 30 µM for CarbZDNaph, CarbZDChin and Rev-5901, respectively. The detailed analysis of mechanism revealed an induction of caspasedependent apoptosis and autophagy. In the presence of chloroquine, an autophagy inhibitor, we observed an increased mortality of cells, implying a cytoprotective role of autophagy. Our in vivo experiment reports tumor growth attenuation in animals treated with CarbZDChin. Compounds CarbZDNaph and Rev-5901 lacked an in vivo efficacy. The results presented in this study display a strong effect of compound CarbZDChin on malignant cell growth. Having in mind the important role of inflammation in cancer development, these results have a significant impact and are worthy of further evaluation.

All cells are equipped to sense changes in their environment and make adaptive responses according to the stimuli. Signal recognition usually occurs at the cell membrane (with the exception of steroid signalling) where the ligand, which can be a small molecule, a peptide or a protein, binds its cognate receptor. This results in a change in the conformation of the receptor which in turn can regulate the production of second messengers. Second messengers can now modulate specific pathways which control gene expression and modify various aspects of cell behaviour. The signalling cascade is terminated by the removal of second messenger and/or by desensitisation of the receptor to the extracellular signal. Cyclic guanosine monophosphate (cGMP) was first identified in the rat urine and since then has emerged as an important second messenger regulating diverse cell processes. Subsequent to its discovery in mammalian cells, enzymes responsible for its synthesis (guanylyl cyclases), hydrolysis (phosphodiesterases) and its most common effectors (cGMP-dependent protein kinases) were identified. Guanylyl cyclases exist in two forms, cytosolic and membrane bound. Both have a conserved guanylyl cyclase domain, but differ in their choice of ligands, overall structure and tissue localization. It is now known that cytosolic and the membrane-bound forms are involved in eliciting distinct cellular responses. Receptor guanylyl cyclase C (GC-C) was identified as the target for a family of heat-stable enterotoxin toxins (ST) produced by enterotoxigenic E.coli. Stable toxin-mediated diarrhoeas are observed frequently in infants and contribute significantly to the incidence of Travellers’ Diarrhea. Early studies demonstrated that the effects of ST were mediated by an increase in intracellular cGMP levels in intestinal cells, and the receptor for ST was almost exclusively expressed in the apical microvilli of the intestinal brush-border epithelia. Effectors of cGMP in intestinal cells include protein kinase G (PKG), cyclic nucleotide gated ion channel 3 (CNG), and the cystic fibrosis transmembrane conductance regulator (CFTR). ST is an exogenous ligand which serves as a hyperagonist for GC-C, in comparison with the endogenous ligands guanylin and uroguanylin, which maintain fluid-ion homeostasis in the intestinal epithelia. The GC-C/cGMP signal transduction pathway also modulates intestinal cell proliferation along the crypt-villus axis by exerting a cytostatic effect on the epithelial cells, thereby regulating their turnover and neoplastic transformation. The current study describes in molecular detail two signalling pathways, one impinging on and one emerging from GC-C, which regulate colonic cell proliferation. The first part identifies the cross-talk and cross-regulation of GC-C and c-src. The second part delves into the molecular basis of GC-C/cGMP-mediated cytostasis and its effect on colonic tumorigenesis. Cross-talk between signalling pathways is believed to play a key role in regulating cell physiology. Phosphorylation of signalling molecules by protein kinases is frequently used as a means of achieving this cross-regulation. Aberrant hyperactivation of the c-src tyrosine kinase is an early event in the progression of colorectal cancer, and activated c-src specifically phosphorylates a number of proteins in the cell. It was found that c-src can phosphorylate GC-C in T84 colorectal carcinoma cells, as well as in the rat intestinal epithelia. Tyrosine phosphorylation of GC-C resulted in attenuation of ligand-mediated cGMP production; an effect which was reversed by chemical or transcriptional knockdown of c-src. These effects were found to be cell line-independent and relied only on the extent of c-src expression and activation in the cell. Mutational analysis revealed GC-C to be phosphorylated on a conserved tyrosine residue (Y820) in the guanylyl cyclase domain. The sequence of GC-C around Y820 allowed for efficient phosphorylation by c-src, and indeed, kinase assays indicated that the affinity of c-src for the GC-C Y820 peptide was one of the highest reported till date. A phospho-mimetic mutation at this site, which mimics a constitutively phosphorylated receptor, resulted in a sharp reduction of guanylyl cyclase activity of the receptor, reiterating the inhibitory role of Y820 phosphorylation on GC-C activity. Phosphorylation of GC-C at Y820 generated a docking site for the SH2 domain of c-src which could interact and thereby co-localize with GC-C on the cell membrane. Intriguingly, this interaction resulted in activation of c-src, setting-up a feed-forward loop of inhibitory GC-C phosphorylation and c-src activation. Treatment of colorectal carcinoma cells with ligands for GC-C reduces cell proliferation and inhibits tumorigenesis. It was observed that this cytostatic effect can be modulated by the status of c-src activation, and consequently, the fraction of tyrosine phosphorylated GC-C in these cells. Since activation of c-src is a frequent event in intestinal neoplasia, phosphorylation of GC-C by active c-src may be one of the means by which the cytostatic effects of GC-C agonists (guanylin and uroguanylin) in the intestine are bypassed, thereby leading to cancer progression. Colonisation of the gut with enteropathogenic microorganisms induces secretion of IFNγ from the host mucosal immune system, which subsequently activates c-src in intestinal epithelial cells. Ligand-stimulated activity of GC-C was found to be reduced in IFNγ treated cells. This could be one of the host defence mechanisms initiated in response to enterotoxigenic E. coli infection. These results provide the first evidence of cross-talk between a receptor guanylyl cyclase and a tyrosine kinase that results in heterologous desensitisation of the receptor. Populations with a higher incidence of enterotoxigenic E.coli infections appear to be protected from intestinal neoplasia. It was found that mice lacking GC-C, and therefore unable to respond to ST, displayed an increased cell proliferation in colonic crypts and enhanced carcinogen-induced aberrant crypt foci formation, which is a surrogate marker for colorectal carcinogenesis. However, pharmacological elevation of cGMP was able to efficiently induce cytostasis even in GC-C knockout mice, indicating a key role for cGMP in regulating colonic cell proliferation. Through microarray analyses, genes regulated by ST-induced GC-C activation in T84 colorectal carcinoma cells were identified. Genes involved in a number of cellular pathways were differentially expressed, including those involved in signal transduction, protein and solute secretion, transcriptional regulation and extracellular matrix formation. One of the genes found to be significantly up-regulated was the cell-cycle inhibitor, p21. The increase in p21 expression was validated at both the transcript and protein level. This p53-independent up-regulation of p21 was coupled to the activation of the cGMP-responsive kinase, PKGII, since knockdown of PKGII using specific siRNAs abolished ST-induced p21 induction. Activation of PKGII led to phosphorylation and activation of the stress responsive p38 MAPK. Similar to what was seen following knockdown of PKGII, inhibition of p38 MAPK activity attenuated the up-regulation of p21 in response to cGMP, indicating that PKGII and p38 MAPK could be a part of a pathway regulating p21 expression. It was found that active p38 MAPK phosphorylated the ubiquitous transcription factor SP1, enhancing its occupancy at the proximal p21 promoter. Therefore, SP1 could be one of the factors linking cGMP to transcription of the p21 mRNA. Chronic activation of GC-C led to nuclear accumulation of p21 in colonic cells, which entered a quiescent state. These cells arrested in the G1 phase of the cell cycle, consequent to p21-dependent inhibition of the G1 cyclin-CDK complexes. A fraction of these quiescent cells stochastically initiated a cGMP-dependent senescence programme and displayed all the hallmarks of senescent cells, including flattened cell morphology, expression of SA- galactosidase and formation of senescence-associated heterochromatic foci. Activation of senescence and loss of tumorigenicity in these cells was crucially dependent on the up-regulation of p21. This irreversible exit from the cell cycle due to cGMP-mediated activation of the PKGII/p38/p21 axis was well correlated with reduced colonic polyp formation in mice exposed to ST. In summary, these observations may provide a possible explanation for the low incidence of colorectal carcinoma seen in countries with a high incidence of ST-mediated diarrhoea. Interestingly, c-src mediated tyrosine phosphorylation of GC-C prevented p21 accumulation following ligand application. The findings described in this thesis may have important implications in understanding the molecular mechanisms involved in the progression and treatment of colorectal cancer.

La P-glycoprotéine (P-gp) est une protéine transmembranaire de la famille des ATP binding cassette transporteurs. Elle est impliquée dans l’efflux du milieu intracellulaire vers le milieu extracellulaire d’une grande variété de médicaments anticancéreux. Elle peut être responsable de la diminution de la biodisponibilité orale et de la concentration intra-tumorale des médicaments qui en sont substrats. Elle peut notamment être surexprimée par les cellules cancéreuses des adénocarcinomes du colon naïfs de tout traitement, suggérant une résistance naturelle de cette tumeur et également après une chimiothérapie. Notre premier travail in vivo a documenté le caractère substrat de la P-gp de l’evérolimus, inhibiteur de mTOR indiqué dans divers cancers (rein, tumeurs neuroendocrines d’oringine pancréatique et sein), jusqu’à maintenant uniquement étudié dans des modèles in vitro. Une augmentation significative de l’AUC de l’evérolimus administré par voie orale est observée chez des souris mdr1a-/b- comparées à des souris mdr1a+/1b+. Une amélioration significative de la biodisponibilité orale de l’evérolimus est aussi notée chez des souris prétraitées par le lapatinib (Tyverb®), inhibiteur des tyrosines kinases (EGFR et HER2) indiqué dans le cancer du sein, par rapport aux souris ayant reçu l’evérolimus seul. Ce résultat est accompagné d’une inhibition de l’expression de la P-gp intestinale par le lapatinib mesurée par la technique de Western Blot. Enfin, une étude préclinique menée chez des souris porteuses d’une xénogreffe colorectale mutée KRAS montre une activité anti-tumorale certaine des deux médicaments utilisés seuls et en schéma séquentiel. Notre seconde étude a montré pour la première fois que le cétuximab (Erbitux®), anticorps anti-EGFR, inhibe la fonctionnalité de la P-gp dans deux lignées cellulaires surexprimant la P-gp (les cellules IGROV-1 et les HEK P-gp) indépendamment de leur statut EGFR et entraîne chez des souris porteuses d’une xénogreffe colorectale une augmentation significative de la biodisponibilité orale et de la concentration intra-tumorale du SN-38, métabolite actif de l’irinotécan (Campto®) administré par voie orale. Le cétuximab étant prescrit en association avec l’irinotécan chez des patients atteints d’un cancer colorectal métastasé, initialement réfractaire à l’irinotécan, ces résultats pourraient en partie expliquer la réversion de la résistance à l’irinotécan par le cétuximab par une inhibition de l’efflux de la P-gp. Grâce à l’étude de deux associations de médicaments «lapatinib-evérolimus» et «cétuximab-irinotécan», nous avons démontré l’intérêt de l’étude de l’inhibition de la P-gp avec les traitements les plus récents, notamment son rôle dans l’amélioration de la biodisponibilité orale de chimiothérapies utilisées par voie orale. / P-glycoprotein (P-gp) is a membrane transporter and belongs to the ATP-binding cassette (ABC) transporter super family. P-gp decreases oral bioavailability of substrate drugs and can cause multidrug resistance in tumor cells by decreasing intracellular drug levels. P-gp is overexpressed in colorectal carcinoma naturally resistant to chemotherapy. The aim of our first study was to document the in vivo transport of everolimus (Afinitor®), a mTOR inhibitor, by P-gp. A significant increase of everolimus oral bioavaibility was observed in mdr1a-/1b- mice compared to the wild type. In addition, a significant increase of everolimus oral bioavaibility was showed in mice that received a lapatinib pre-treatment (a dual EGFR/HER2 tyrosine kinase inhibitor) compared to mice that received everolimus alone. These results were accompanied by a significant decrease of P-gp expression in duodenum segment in lapatinib pre-treated group as compared to control group. Finally, each drug given alone or in association showed a major antitumor activity in a xenograft model of human colorectal carcinoma with KRAS mutation. Our second study showed for the first time that cetuximab (Erbitux®), a monoclonal antibody directed towards EGFR, inhibits P-gp functionality in two cell lines overexpressing P-gp (IGROV-1 and HEK P-gp cells) independently of EGFR status and leads to significant increases of oral bioavailability and intratumoral concentration of SN-38, the active metabolite of irinotecan (Campto®) in mice bearing colorectal carcinoma xenograft. Cetuximab is used in combination with irinotecan in patients with metastatic colorectal cancer, initially refractory to irinotecan, our results may partly explain the reversion of resistance to irinotecan by inhibiting P-gp efflux by cetuximab. In conclusion, our results showed the interest to study the effect of recent anticancerous drugs on P-gp, including their ability to improve oral bioavailability of oral chemotherapy used.

The aim of the dissertation was to find out the specifics of nursing care in clinical and community practice with patients with colorectal cancer using the model of M. E. Levine. Furthermore, to find out which of these specifics are missing in the mentioned nursing model and to modify the nursing documentation according to the chosen conceptual model of M. E. Levine. In the empirical part we used a combination of qualitative and quantitative research which was carried out as part of the grant project GAJU 048/2015/S. The pre-research, conducted interviews with 8 informants was used to identify the key data for answering research questions and creating a custom-designed questionnaire. A non-standardized questionnaire was distributed across the Czech Republic to 300 patients with colorectal cancer. We also designed nursing documentation, which was verified by focus group with 35 nurses from clinical and community practice. The results show that patients are limited in areas of contact with friends, normal traffic, traveiling, and fear for themselves and their loved ones to maintain social integrity. In the principle of maintaining structural integrity, problems with diet, alcohol consumption, diarrhea, current treatment management, stoma and stoma type have been identified. In the field of energy conservation the influence of length of diagnosis and colonoscopy performed as part of preventive examination, pain sensation, and enough energy for normal daytime life have been confirmed. In the principle of conservation personality integrity, we have found that the length of time determines the fear of getting stoma, learning individuals with the same disease, experiencing negative feelings, and limiting private life. The work provides a comprehensive framework of the issue of patients with colorectal cancer. It provides evidence of the possibility of using M. E. Levine's conceptual model in colorectal cancer patients.

Sodium butyrate (NaBt) is a four-carbon short chain fatty acid, produced naturally in colon as the end product of the bacterial anaerobic metabolism on dietary fibers. It was previously shown that NaBt can induce differentiation and may inhibit proliferation. The objective of this study was to investigate the effect of NaBt-induced differentation on inflammatory pathways in HT29 colon cancer cells. For this purpose, first, cells were treated with varying concentrations of NaBt from 1-5 mM and amount required to induce differentiation was determined as 3 mM. To understand the effect of NaBt on inflammation, the NF-kappaB pathway (p50 and p65) was investigated. Immunofluorescent staining showed increased nuclear translocation of p50 subunit with no remarkable change in subcellular localization of p65 / moreover a synergistic effect was observed when cells were co-treated with NaBt and an NF-kappaB repressor, Bay 11-7085 / implying the formation of repressive p50 homodimers in the nucleus. Our preliminary chromatin immunoprecipitation results showed that p65 recruitment v to the promoters of ICAM-1 was reduced, whereas p50 recruitment was increased. However, analysis of NF-kappaB target genes showed that cells treated with 3 mM NaBt have higher expression of the cytokines IL1-&beta / and TNF-&alpha / , adhesion molecules ICAM-1 and VCAM-1 but not COX-2. These results suggest that NaBt-induced differentiation could cause the emergence of an inflammatory signal in HT29 cells as an anti-tumor mechanism, independent from the NFkappaB activity. This work will be important in understanding the role of SCFAs in the colon microenvironment and may provide alternative therapeutic options in colorectal cancer.

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