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.

No description available.

No description available.

La capacité des cellules à être invasives et métastasiques est une caractéristique fondamentale de la malignité tumorale. Nous avons récemment montré que le facteur d’ADP-ribosylation 1 (ARF1) est surexprimé dans les lignées cellulaires hautement invasives du cancer du sein et que la stimulation du récepteur au facteur de croissance épidermique (EGFR) peut activer cette isoforme pour contrôler la migration ainsi que la prolifération. Cependant, le rôle de cette GTPase dans la régulation du processus d’invasion cellulaire et les mécanismes moléculaires associés demeure inconnu. Nous avions comme objectifs dans cette thèse, de définir les voies de signalisation sous le contrôle d’ARF1 dans les cellules de cancer du sein et démontrer que l’expression et l’activation de cette GTPase est associée à un phénotype hautement invasif. Nos études démontrent que la modulation de l'expression et l'activité d’ARF1 affecte la capacité des cellules MDA-MB-231 (pour M. D. Anderson-metastatic breast-231), une ligne hautement invasive, à dégrader la matrice extracellulaire via l'activité de la métalloprotéinase MMP-9. ARF1 contrôle les deux principales structures impliquées dans l'invasion, en jouant sur la maturation d’invadopodes ainsi que la relâche de microvésicules membranaires. D’un point de vue mécanistique, l'axe de signalisation ARF1, RhoA-RhoC et la chaine légère de la myosine (MLC) explique ces phénomènes. De plus, nous démontrons que l'un des mécanismes par lequel ARF1 régule la migration est en contrôlant l'assemblage des points adhésions focaux et ce, dans plusieurs types de cellules cancéreuses du sein. ARF1, en étant un membre du complexe d’adhésion, réglemente le recrutement et l’activité de protéines clés à la β1-intégrine tels que la paxilline, la talin et la kinase d’adhésion focale (FAK). Pour finir, nous rapportons que ARF1 et ARF6 ont un rôle majeur dans la transition épithélio-mésenchymateuse. ARF1 est retrouvé fortement exprimé dans les tissus de sous-types les plus agressifs et les plus avancés de cancer du sein. Dans un modèle murin, la modulation à la baisse de l’expression d’ARF1 dans les cellules MDA-MB-231 corrèle avec la diminution de croissance des tumeurs primaires et l’installation des métastases pulmonaires. De plus, nous rapportons que la surexpression des ARF dans des cellules non invasives, les MCF7 (pour Michigan Cancer Foundation-7), permet la nidification de métastases. En effet, dans les MCF7, ARF1 contrôle l’adhésion intercellulaire via la β-caténine et l’E-cadhérine, promeut l’activation de l’oncogène Ras (pour Rat Sarcoma/ Rat Fibrosarcoma virus) et l’expression de plusieurs inducteurs de transition épithélio-mésenchymateuse comme snail et slug. De plus, ARF1 contrôle l’invasion, la prolifération cellulaire et même la résistance à certains agents chimio-thérapeutiques. Globalement, nos études identifient ARF1 comme un interrupteur moléculaire de la progression tumorale et suggèrent que la limitation de son expression/activité pourrait améliorer le devenir des patients atteints du cancer du sein. / Invasive and metastatic chapacities are fundamental features for tumor malignancy. We have recently shown that the ADP-ribosylation factor 1 (ARF1) is over-expressed in highly invasive breast cancer cell lines and stimulation of the epidermal growth factor receptor (EGFR) may activate this isoform to regulate migration and proliferation. However, the role of this GTPase in regulating cell invasion process and related molecular mechanisms remain unknown. In this thesis, we had as objectives, to define the signaling pathways under the control ARF1 in breast cancer cells and show that the expression and activation of the GTPase is associated with highly invasive phenotype. Our studies show that the modulation of the expression and activity of ARF1 affect the ability of MDA-MB-231 cells (M. D. Anderson-metastatic breast-231), a highly invasive line, to degrade the extracellular matrix via the activity of the metalloproteinase MMP-9. ARF1 controls the two main structures involved in the invasion, playing on invadopodia maturation and shedding of membrane microvesicles. The molecular mechanisms involve the regulation of RhoA and RhoC activity by ARF1 and the following downtream events associated with and the myosin light chain (MLC) phosphorylation. Furthermore, we demonstrate that ARF1 also regulates migration by controlling the assembly of focal adhesion complexes in many types of breast cancer cells. ARF1, also prensent in adhesion complexes, regulates the recruitment and activity of key proteins such as paxillin, talin and focal adhesion kinase (FAK) to β1 integrin. Finally, we report that ARF1 and ARF6 play a major role in the epithelial-mesenchymal transition (EMT). ARF1 is found highly expressed in tumor tissue of the most aggressive and advanced subtypes of breast cancer. Lowered expression of ARF1 in vivo in the MDA-MB-231 cells impars tumor growth in primary tumors and inhibits lung metastasis. We report that upregulation of the ARF in non-invasive cells, MCF7 (Michigan Cancer Foundation-7) induce metastasis nidification. Indeed, we show in MCF7 that ARF1 controls intercellular adhesion via the β-catenin and E-cadherin, promotes Ras (Rat Sarcoma/ Rat Fibrosarcoma virus) oncogene activation, and conrols expression of several epithelial-mesenchymal transition markers such as snail and slug. Moreover, we demonstrate that ARF1 controls invasion, proliferation and even resistance to certain chemo-therapeutic agents, in MCF7 cells. Overall, our studies identify ARF1, as a molecular switch of tumor progression and suggest that limiting its expression / activity could improve the outcome of breast cancer patients.

La réparation endovasculaire (EVAR) est une technique minimalement invasive permettant de traiter l’anévrisme de l’aorte abdominale (AAA) par l’entremise d’un stent- graft (SG). L’utilisation d’EVAR est actuellement limitée par de fréquentes complications liées à une guérison inadéquate autour de l’implant. Ce manque de guérison est principalement dû au type de recouvrement polymérique des SG, au milieu pro-apoptotique des AAA et à l’accès réduit aux nutriments et à l’oxygène après EVAR. L’objectif de cette thèse consistait à concevoir un revêtement bioactif permettant d’inhiber l’apoptose et stimuler la croissance des cellules musculaires lisses vasculaires (CMLV), pour ainsi favoriser la guérison des tissus vasculaires autour des SG. La chondroïtine-4-sulfate (CS) a d’abord été choisie, car elle a été identifiée comme un médiateur important de la réparation vasculaire. Il a été démontré que la CS en solution influence directement la résistance à l’apoptose des CMLV, en plus de favoriser la différenciation myofibroblastique chez les fibroblastes. Dans le cadre de ce projet, un premier revêtement à base de CS et de collagène a été créé. Bien que le revêtement permettait d’induire une résistance à l’apoptose chez les CMLV, il se désintégrait trop rapidement dans des conditions aqueuses. Une nouvelle méthodologie a donc été adaptée afin de greffer la CS directement sur des surfaces aminées, à l’aide d’un système utilisant un carbodiimide. Dans le but d’accroître la croissance des CMLV à la surface des revêtements, le facteur de croissance de l’épiderme (EGF) a ensuite été sélectionné. En plus de ses propriétés mitogéniques et chimiotactiques, l’EGF stimule la production d’éléments de la matrice extracellulaire, comme le collagène et la fibronectine. De plus, l’activation du récepteur de l’EGF inhibe également l’apoptose des CMLV. L’EGF a donc été greffé sur la CS. Le revêtement de CS+EGF a démontré une bonne uniformité et bioactivité sur des surfaces de verre aminé. iii iv Dans une 3ème étape, afin de permettre de transposer ce revêtement bioactif sur des implants, plusieurs méthodes permettant de créer des groupements d’amines primaires sur les biomatériaux polymériques comme le PET ou le ePTFE ont été étudiées. La polymérisation par plasma a été choisie pour créer le revêtement CS+EGF à la surface de PET. Une fois de plus, celui-ci a permis d’inhiber l’apoptose des CMLV, dans des conditions pro-apoptotiques, et de favoriser la croissance des cellules. Le revêtement de CS et d’EGF, déposé sur des surfaces aminées, possède des caractéristiques biologiques intéressantes et semble donc prometteur pour favoriser une meilleure guérison autour des SG. / Endovascular aneurysm repair (EVAR) is a minimally invasive technique performed to treat abdominal aortic aneurysm (AAA) through the use of a stent-graft (SG). The usage of EVAR is presently limited by postoperative complications related to an incomplete healing of the surrounding tissues. The materials currently used in SG, the pro- apoptotic phathophysiology of AAA and the limited access to nutrients and oxygen, all limit the wound healing process and proper tissue ingrowth around the implant. The main objective of this thesis was to create of a bioactive coating inhibiting cell apoptosis and increasing vascular smooth muscle cells (VSMC) growth, to promote healing of the vascular tissues surrounding SG. Chondroitin sulfate (CS) was chosen since recent findings have shown that this polysaccharide triggers key mechanisms involved in vascular repair. CS in solution was shown to inhibit apoptosis of VSMC, as well as stimulate myofibroblast differentiation. A coating of CS and collagen was first created for the purpose of this work. Although the coating was shown to increase cell resistance to apoptosis with VSMC, it was not stable enough, since it rapidly disintegrated in aqueous solutions. A new methodology was thus proposed, where CS was grafted right on aminated surfaces, through carbodiimide chemistry. Epidermal growth factor (EGF) was then chosen to increase VSMC growth on the coatings. EGF is a known mitogenic and chemotactif growth factor for VSMC. It also stimulates the production of extracellular matrix elements, such as collagen and fibronectin. The activation of EGF receptor (EGFR) also triggers various cell signalling pathways modulating VSMC resistance to apoptosis. EGF was thus grafted on CS. CS+EGF coating on aminated glassed slides was shown to be uniform and bioactive. Finally, several methodologies to produce primary amines on polymeric biomaterials, such as PET and ePTFE, were studied in order to eventually transfer the v vi coating on implants. Plasma polymerization was chosen to create the CS+EGF coating. Once again the coating was shown to decrease VSMC apoptosis, in apoptotic conditions, and favour cell growth. Overall, the CS and EGF coating on aminated surfaces possesses interesting biological features and is a promising avenue to stimulate vascular healing around SG.

<p>Receptor epidermalnog faktora rasta (EGFR) pripada porodici receptora protein-tirozin kinaze čija je aktivacija povezana sa proliferacijom malignih, invazijom, inhibicijom apoptoze, tumorskom angiogenezom i metastatskim &scaron;irenjem stoga ima važnu ulogu u karcinogenezi i tumorskoj progresiji. Aktivirane mutacije se odvijaju oko katalitičkog tirozin kinaza domena. Biopsijski, citolo&scaron;ki i hirur&scaron;ki uzorci se koriste u detekciji EGFR mutacija u momentu postavljanja dijagnoze adenokarcinoma ili karcinoma sa komponentom adenokarcinoma, najpouzdanije lančanom reakcijom polimeraze. Činjenica da primena ciljane molekularne terapije tirozin kinaza inhibitorima kod obolelih sa EGFR mutiranim adenokarcinomom pluća pobolj&scaron;ava prognozu bolesti, postoji rezistencija kod pojedinih tipova EGFR mutacija i povezanost histopatolo&scaron;kim i imunohistohemijskim karakteristikama tumora, da je bronholo&scaron;ki uzorak često jedini uzorak u kome je potrebno odrediti i molekularni profil tumora osnovni cilj ove disertacije bio je da se odredi učestalost i tip EGFR mutacija i povezanost sa karakteristikama adenokarcinoma. Da bi se taj cilj realizovao postavljeni su sekundarni ciljevi odnosno da se: izvr&scaron;i histopatolo&scaron;ka reklasifikacija adenokarcinoma pluća na osnovu kriterijuma koje je postavila internacionalna asocijacija za proučavanje carcinoma pluća, američko torakalno dru&scaron;tvo i evropsko respiratorno dru&scaron;tvo; odredi ekspresija TTF-1 u adenokarcinomu pluća i povezanost sa EGFR mutacionim statusom; odredi učestalost, tip i povezanost EGFR mutacija sa predominantnim tipom adenokarcinoma i utvrdi da li bronhoskopska biopsija može da bude reprezentativni uzorak za određivanje EGFR mutacionog statusa. Histopatolo&scaron;ka građa adenokarcinoma pluća u hirur&scaron;kim uzorcima je heterogenija u odnosu na biopsijske uzorke i ta razlika je statistički značajna (p&lt;0,001). Acinarno predominantni tip je najzastupljeniji u hirur&scaron;kim i biopsijskim uzorcima bez statistički značajne razlike u raspodeli predominantnih tipova u njima (p=0,65883). Predominantni tip u primarnom tumoru određuje predominantni tip u limfogenim metastazama. EGFR mutacije tipa insercija na egzonu 21 i L858R mutacija na egzonu 20 su detektovane kod tri od 60 (5%) bolesnika u pet od 120 uzoraka (tri hirur&scaron;ka i dva biopsijska uzorka), če&scaron;će kod žena, starijih od 60 godina, pu&scaron;ača i u solidno predominantnom tipu. Ne postoji statistički značajna razlika u koncentraciji izolovane DNK između EGFR mutiranih i wt EGFR adenokarcinoma u biopsijskim (p=0,132) i hirur&scaron;kim uzorcima (p=0,641). Procenat invalidnih rezultata prilikom određivanja EGFR mutacionog statusa u je veći u biopsijskim uzorcima u odnosu na hirur&scaron;ke uzorke. Postoji statistički značajna razlika izmeĐu broja TTF-1 pozitivnih i TTF-1 negativnih adenokarcinoma (p&lt;0,001), ali ne i u raspodeli ovih bolesnika prema polovima (p=0,1231), prosečnoj starosti, pu&scaron;ačkim navikama (p=0,6488) i prosečnoj veličini tumora (p=0,21). Postoji pozitivna korelacija između TTF-1 pozitivne ekspresije i EGFR mutacionog statusa stoga TTF-1 pozitivna ekspresija može da bude prediktor pozitivnog EGFR mutacionog statusa. Bronhoskopska biopsija je reprezentativni uzorak za određivanje EGFR mutacionog statusa zato &scaron;to: većina dijagnostičkih biopsijskih uzoraka ima vi&scaron;e od 100 očuvanih tumorskih ćelija, nema razlike u raspodeli predominantnih tipova u odnosu na hirur&scaron;ke uzorke, EGFR mutacije se detektuju u uzorcima sa manje od 100 tumorskih ćelija i manje od 20% volumenske gustine tumorskog tkiva, razlika između koncentracije izolovane DNK u EGFR mutiranim i wt EGFR adenokarcinomima u biopsijskim i hirur&scaron;kim uzorcima nije statistički značajna (p=0,132 i p=0,641).</p> / <p>Epidermal growth factor receptor (EGFR) belongs to the family of protein-tyrosin kinase family, whose activation is associated with the proliferation of malignant cells, invasion, inhibition of apoptosis, tumor angiogenesis and metastatic spread and thus plays an important role in carcinogenesis and tumor progression. Activated mutations take place around the catalytic tyrosine kinase domain. Biopsy, cytological and surgical specimens are used for the detection of EGFR mutations at the time of diagnosis of adenocarcinoma or carcinoma with an adenocarcinoma component, most reliably using a polymerase chain reaction. The fact that the application of molecular tyrosin kinase inhibitor therapy to patients with EGFR mutated lung adenocarcinoma improves the prognosis of the disease, there is resistance in certain types of EGFR mutations and connection with histopathological and immunohistochemical characteristics of tumor, that the bronchoscopic specimen is often the only specimen in which it is necessary to determine the molecular profile of the tumor, the primary objective of this thesis is to determine the frequency and type of EGFR mutations and their connection with the characteristics of adenocarcinoma. In order to realize this objective, the following secondary objectives have been set: to execute histopathological reclassification of lung adenocarcinoma based on the criteria set by the International Association for the Study of Lung Cancer, the American Thoracic Society and European Respiratory Society; determine the expression of TTF-1 in lung adenocarcinoma and connection with EGFR mutation status; determine the frequency, type and connection of EGFR mutations with predominant type of adenocarcinoma and confirm whether bronchoscopic biopsy may be a representative specimen for the determination of EGFR mutation status. Histopathological material of lung adenocarcinoma in surgical specimens is more heterogeneous in relation to biopsy specimens and such difference is statistically significant (p&lt;0,001). Acinar predominant type is the most common in surgical and biopsy specimens with no statistically significant differences in the distribution of predominant type among them (p=0,65883). The predominant type in the primary tumor determines the predominant type in lymphatic metastases. EGFR mutations in the type of insertions on exon 21 and L858R mutations on exon 20 have been detected in three out of 60 (5%) of patients in five out of 120 specimens (three surgical and two biopsy samples), more often in women older than 60, smokers and in a solid predominant type. There are no statistically significant differences in the concentration of isolated DNA between EGFR mutated and wt EGFR adenocarcinoma in biopsy (p=0,132) and surgical specimens (p=0,641). The percentage of invalid results in determining the EGFR mutation status is higher in biopsy specimens compared to the surgical specimens. There is a statistically significant difference between the number of TTF-1 positive and TTF-1 negative adenocarcinoma (p&lt;0,001), but not in the distribution of these patients according to gender (p=0,1231), average age, smoking habits (p=0,6488) and average tumor size (p-0,21). There is a positive correlation between TTF-1 positive expression and EGFR mutation status and therefore TTF-1 positive expression can be a predictor of positive EGFR mutation status. Bronchoscopic biopsy is a representative sample for the determination of EGFR mutation status because: most diagnostic biopsy specimens have more than 100 preserved tumor cells, there is no difference in the distribution of predominant types in relation to surgical specimens, EGFR mutations are detected in samples with less than 100 tumor cells and less than 20% of volume density of tumor tissue, the difference between the concentration of isolated DNA in EGFR mutated and wt EGFR adenocarcinoma in biopsy and surgical specimens is not statistically significant (p=0,132 and p=0,641).</p>

Dans un contexte où la forte prévalence du cancer du sein chez les femmes demeure depuis plusieurs années un enjeu de société majeur, les nouvelles stratégies visant à réduire la mortalité associée à cette maladie sont le sujet de nombreuses recherches scientifiques. Les facteurs d’ADP-ribosylation sont des petites protéines G monomériques importantes pour la réorganisation du cytosquelette d’actine, le remodelage des lipides membranaires et la formation de vésicules. Notre laboratoire a précédemment montré qu’ARF1 est surexprimée dans les cellules hautement invasives du cancer du sein et contribue à leur phénotype migratoire accru. Dans le cadre de ce mémoire, nous avons défini le rôle de cette GTPase dans la migration de telles lignées cellulaires. Pour ce faire, nous avons étudié le rôle d’ARF1 dans l’activation de Rac1, un membre de la famille des GTPases Rho connu pour son implication dans la formation de lamellipodes ainsi que dans la migration cellulaire. Globalement, nous avons déterminé que l’activation d’ARF1 permet l’activation subséquente de Rac1 ainsi que de la voie de signalisation nécessaire au processus de migration. Par une approche d’interférence à l’ARN dans les cellules MDA-MB-231, nous avons d’abord montré la contribution essentielle de Rac1 la migration dépendante d’ARF1. Puis, de façon à établir le mécanisme derrière cette régulation, nous avons montré que l’inhibition de l’expression endogène d’ARF1 altère l’activation de Rac1 dépendante de l’EGF. Nous avons ensuite examiné les conséquences d’une telle inhibition sur les partenaires d’interaction de Rac1. Nous avons découvert qu’ARF1 et Rac1 forment un complexe constitutif, puis qu’ARF1est nécessaire à l’association de Rac1 à IRSp53, une protéine importante dans la formation de lamellipodes. La translocation dépendante de l’EGF du complexe Rac1/IRSp53 à la membrane plasmique est également sous le contrôle d’ARF1. En conclusion, cette étude fournit un nouveau mécanisme par lequel ARF1 régule la migration cellulaire et identifie cette GTPase en tant que cible pharmacologique prometteuse pour freiner le développement des métastases chez les patients atteints du cancer du sein. / ADP-ribosylation factors (ARFs) are monomeric G proteins important for actin cytoskeleton reorganization, lipid membrane remodeling, and vesicule formation. Our laboratory has previously shown that ARF1 is overexpressed in highly invasive breast cancer cells and contribute to their enhanced proliferation and migration phenotype. In this study, we propose to define the role of ARF1 on the activation of Rac1, an important member of the Rho family of GTPases implicated in the formation of lamellipodia and in the migration process. Globally, we evaluated whether ARF1 activation could affect Rac1 activation and the signaling pathway necessary for cell migration. Using an RNAi approach in MDA-MB-231 breast cancer cells, we first determined the essential contribution of Rac1 in ARF1-dependant migration. Mechanistically, endogenous inhibition of ARF1 expression altered EGF-dependent Rac1 activation. We next investigated the consequences of such effect on Rac1 interaction partners. We showed that ARF1 and Rac1 are constitutively complexed but that ARF1 is necessary for EGF-dependent Rac1 association with IRSp53, an essential protein for lamellipodia formation. When unable to interact, Rac1/IRSp53 complex translocation to plasma membrane was considerably inhibited. In conclusion, this study provides a new mechanism by which ARF1 regulates cell migration and identifies this GTPase as a promising pharmacological target to reduce metastasis formation in breast cancer patients.

Little is known about the signaling pathways that contribute to treatment response in advanced stage head and neck tumors. Increased expression of epidermal growth factor receptor (EGFR) and downstream pathways such as nuclear factor kappa B (NFκB) are implicated in aggressive tumor phenotypes and limited response to therapy. This study explored the rationale for combining the proteasome inhibitor bortezomib with the EGFR inhibitor gefitinib in a subset of head and neck squamous cell carcinomas with high EGFR gene amplification. Drug responses of gefitinib and bortezomib as single agents and in combination within head and neck squamous cell carcinoma cell lines were analyzed using MTS assays. The effects of gefitinib on the activation of EGFR and itsthree major downstream pathways, Akt, STAT3 and MAPK were determined by western blotting. The activation status of NFκB and the effects of bortezomib on the canonical pathway were assessed by DNA binding assays. Resistance to lower doses of gefitinib was associated with elevated EGFR and activated Akt expression. Gefitinib was able to effectively inhibit activation of STAT3, Akt and MAPK in HNSCC to varying degrees depending on EGFR expression status. Bortezomib treatment inhibited TNFα –induced nuclear NFκB/RelA expression but demonstrated variability in levels of baseline nuclear NFκB/RelA expression between sensitive and resistant cell lines. Bortezomib effectively suppresses NFκB/RelA nuclear activation but demonstrates additional modes of cellular toxicity beyond the NFκB pathway in sensitive cell lines. Further understanding of tumor response to the targeted inhibitors gefitinib and bortezomib may provide novel approaches in managing HNSCCs.

No description available.

INTRODUÇÃO: Os astrocitomas difusamente infiltrativos são os tumores mais freqüentes de Sistema Nervoso Central (SNC) com uma taxa de 5-7 novos casos por 100.000 pessoas ano. São tumores altamente invasivos e estão associados com alterações de alguns genes como EGF (fator de crescimento epidérmico) e o EGFR (receptor do fator de crescimento epidérmico), que podem criar um aumento da atividade mitogênica, acarretando aumento de proliferação e maturação celular, apoptose, angiogênese e metástase. O nível de expressão destes genes pode ser influenciado por alterações genéticas, como a presença de polimorfismos. Uma mudança única de base (SNP) pode alterar a expressão gênica e, sendo assim, estar associada ao aumento do risco de desenvolver astrocitomas. Nesse trabalho, foram analisados 2 SNPs na região não traduzida (c.-191C>A e c.-216G>T) e um SNP no exon 16 (c.2073A>T) do gene EGFR, e um outro SNP na região não traduzida no gene EGF (c.61A>G). Os SNPs foram associados a expressão gênica do EGFR e a sobrevida dos pacientes. MÈTODOS: Foi realizado um estudo caso-controle com 193 casos de astrocitomas difusamente infiltrativos e 200 controles por amplificação por PCR seguido de digestão enzimática. Os produtos digeridos das amostras foram analisados por eletroforese em gel de agarose e poliacrilamida e corados com brometo de etídeo. A expressão gênica foi realizada após extração de RNA do tecido tumoral seguida de transcrição reversa e PCR em tempo real. Testes de qui-quadrado, odds ratio (OR), intervalo de confiança 95% (IC95%), t de Student e curvas de Kaplan-Meier foram realizados para análises estatística. RESULTADOS: A análise das freqüências dos genótipos dos polimorfismos mostrou uma diferença na distribuição entre casos e controles para o polimorfismo c.2073A>T. Pacientes com o genótipo TT apresentou um menor risco para astrocitoma quando comparados com o genótipo AA (OR=0,51, IC95%=0,29-0,99). Nenhuma correlação foi encontrada para os outros polimorfismos analisados. Também não foi encontrada correlação entre os genótipos dos polimorfismos e os níveis de expressão de EGFR e a sobrevida dos pacientes. CONCLUSÃO: Nosso trabalho mostrou haver um possível fator de proteção quando o paciente é portador do genótipo TT, o que pode levar a uma diminuição do risco de desenvolver o tumor. Pacientes com genótipo TT do polimorfismo c.2073A>T do gene EGFR apresentam um menor risco para astrocitomas difusamente infiltrativos do que os com o genótipo AA. / INTRODUCTION: Diffusely infiltrative astrocytomas are the most frequent tumors of the Central Nervous System (CNS) with a rate of 5-7 new cases in 100,000 individuals per year. They are highly invasive, and they are associated to alterations in some genes as EGF (epidermal growth factor) and EGFR (epidermal growth factor receptor), which may increase mitogenic activity, leading to increase of proliferation, cellular maturation, apoptosis, angiogenesis, and metastasis. Genetic alterations, as presence of polymorphisms of single nucleotide change (SNP) could influence their expression level, and thus could be associated to increased risk in developing astrocytomas. In the present study, two SNP of non-coding region (c.-191C>A and c.-216G>T) and one SNP in exon 16 (c.2073A>T) of EGFR, and another SNP of non-coding region of EGF (c.61A>G) were analyzed. The SNPs were associated to EGFR expression level and to survival time. METHOD: a case-control study of 193 of diffusely infiltrative astrocytomas and 200 controls was carried out, with PCR amplification and enzymatic digestion, which products were analyzed in agarose gel or polyacrylamide gel electrophoresis stained by ethidium bromide. EGFR expression level was studied by real time PCR after RNA extraction followed by reverse transcription of tumor tissues compared to epileptic non-neoplastic brain tissues. Stastistical analysis were performed by chi-square, odds ratio (OR), 95% confidence interval (95% CI), Student-t test and Kaplan Meier. RESULTS: The polymorphic genotype frequency was different between case and controls for the polymorphism c.2073A>T. Patients with TT genotype presented lower risk to develop astrocytoma when compared to genotype AA (OR=0.51, CI95%=0.29- 0.99). No other correlation was observed for the remaining studied polymorphisms. There was neither correlation between the polymorphic genotypes and the EGFR expression levels nor with survival time. CONCLUSION: The present study showed a possible protection factor in developing astrocytomas for the patients harboring the genotype TT of c.2073A>T polymorphism of EFGR, thus the patients presenting TT genotype have lower risk to develop diffusely infiltrative astrocytoma than patients presenting the genotype AA.