Sporadic breast cancers are mainly attributable to long-term exposure to environmental factors, via a multi-year, multi-step, and multi-path process of tumorigenesis involving cumulative genetic and epigenetic alterations in the chronic carcinogenesis of breast cells from a non-cancerous stage to precancerous and cancerous stages. Epidemiologic and experimental studies have suggested that various dietary compounds like green tea and grape seed may be used as preventive agents for breast cancer control. In this research, I have developed a cellular model that mimics breast cell carcinogenesis chronically induced by cumulative exposures to low doses of environmental carcinogens. I used the chronic carcinogenesis model as a target system to investigate the activity of dietary compounds at non-cytotoxic levels in intervention of cellular carcinogenesis induced by cumulative exposures to pico-molar 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) and benzo[a]pyrene (B[a]P). I used various cancer-associated properties like, reduced dependence on growth factors, anchorage-independent growth, increased cell mobility, and acinar-conformational disruption as measurable endpoints of carcinogenesis. The first part (Part-I) of this dissertation focuses on the understanding the breast cancer progression, importance of environmental carcinogens, role of diet in cancer prevention and importance of epithelial to mesenchymal transition and stem-like cells in chronic carcinogenesis. The next three parts (Part II-IV) focus on understanding the role and mechanisms of dietary compounds in prevention of carcinogenesis and stem-like cell properties. Results in part II revealed the green tea extract at bio-achievable concentration can suppress carcinogen-induced cancerous properties. In Part-III, I compared the four major catechins in green tea extract in suppressing chronic carcinogenesis and the results revealed that epicatechin gallate to be most effective. I also identified that short-term exposure to NNK and B[a]P resulted in elevation of reactive oxygen species, ERK pathway activation and induction of cell proliferation and DNA damage, which can be blocked by green tea catechins. Results in Part-IV describe the roles of properties and markers associated with stem-like cells and the epithelial to mesenchymal transition induced by chronic carcinogenesis and their suppression by green tea catechins and grape seed proanthocyanidin extract. The last section (Part-V) summarizes the findings with their importance and discusses future directions.

This thesis consists of a brief description on cancer, carcinogenesis, the changes in the type and level of dietary fat available in our diets over time and association with the development of certain diseases. The main focus of this research was on omega 6 and omega 3 essential fatty acids (EFA) and their interaction with regards to carcinogenesis.

[Truncated abstract] Introduction: Breast cancer is a heterogeneous disease, resulting in very different outcomes for women with apparently similar tumour characteristics. In order for patients to have optimal treatment, a better understanding of the molecular nature of their disease is required. Aims: The aims of this thesis were: 1) To determine whether methylation of RARβ2, ER, CDH1, BRCA1, CCND2, p16 and TWIST genes are associated with phenotypic features of breast cancer and the prognostic significance of methylation of these genes. 2) To investigate for possible associations between the frequency of methylation at RARβ2, CDH1, ER, BRCA1, CCND2, p16 and TWIST genes and the presence of germ-line variants in the TS, MTHFR, MS, CBS, MTHFD1 and DNMT3B genes, as well as for possible correlations between these polymorphisms and clincopathological features of breast cancer including patient outcome. 3) To determine whether PIK3CA mutations determined clinical phenotype and the prognostic significance of PIK3CA mutations in a large and well characterized cohort of breast cancer patients. Methods: A large and well characterized series of primary breast tumours were selected for methylation of RARβ2, ER, CDH1, BRCA1, CCND2, p16 and TWIST genes using MSP, and for polymorphisms in TS, MTHFR, MS, CBS, MTHFD1 and DNMT3B genes using PCR, PCR-RFLP and PCR-SSCP. Mutations to PIK3CA were detected using F-SSCP. Results and Conclusions: Methylation frequencies ranged from 11% for CCND2 to 84% for ER. More frequent hypermethylation was observed in tumours with poor histological differentiation compared to those with well/moderate differentiation, as well as trends for association with larger tumour size and mutant TP53. Tumours with ER and CDH1 methylation were associated with significantly lower hormone receptor levels, younger age at diagnosis and the presence of mutant p53. TWIST methylation is firstly reported to be associated with significantly older patient age at diagnosis and larger tumour size. Our data suggests that gene methylation may be linked to various pathological features of breast cancer. However, there appears to be little support for a distinctive CpG island methylator phenotype in breast cancer.

Thesis (Ph.D.)--Flinders University, School of Medicine, Dept. of Gastroenterology. / Typescript bound. Includes bibliographical references: (leaves 215-233) Also available in an electronic version via the Web.

Ο καρκίνος της ουροδόχου κύστης αποτελεί την 4η κατά συχνότητα μορφή καρκίνου στους άνδρες στο Δυτικό κόσμο, ακολουθώντας τον καρκίνο του προστάτη, του πνεύμονα και του κόλου. Η επιφανειακή μορφή του καρκίνου της κύστεως έχει το ιδιαίτερο χαρακτηριστικό των πολύ συχνών υποτροπών, οι οποίες ευθύνονται για τη μεγάλη νοσηρότητα της νόσου. Οι πολύ συχνές υποτροπές έχουν, όπως εύκολα γίνεται αντιληπτό, τεράστιο κοινωνικοοικονομικό κόστος, εφ’ όσον ένα σημαντικό τμήμα των πασχόντων αποτελεί μέρος του οικονομικά ενεργού πληθυσμού. Η καρκινογένεση δεν είναι μια απλή διαδικασία, αλλά μια αλληλουχία αλλαγών οι οποίες αφορούν τους κυτταρικούς μηχανισμούς αύξησης, διαφοροποίησης και απόπτωσης και οδηγούν στη μετατροπή ενός φυσιολογικού κυττάρου σε νεοπλασματικό. Ως «Χημειοπρόληψη» ορίζεται η χρήση ειδικών φυσικών ή συνθετικών χημικών ουσιών που μπορούν να παρέμβουν σε κάποια από τα μοριακά αυτά γεγονότα και να προλάβουν, καταστείλουν ή αναστρέψουν, την εξέλιξη προκαρκινικών βλαβών σε διηθητικό καρκίνο. Η διαφορά στην επίπτωση του νεοπλάσματος και τα διαφορετικά κλινικοπαθολογοανατομικά χαρακτηριστικά του καρκίνου της ουροδόχου κύστεως ανάμεσα στα δύο φύλα, υποδεικνύουν ένα σημαντικό ρόλο των ορμονών του φύλου στην παθογένεια του νεοπλάσματος. Υποθέσεις μόνο γίνονται για τη σημασία των οιστρογόνων στην ανάπτυξη καρκίνου της ουροδόχου κύστεως, αφού ακόμα ο ρόλος τους δεν έχει αποσαφηνιστεί. Τα οιστρογόνα ασκούν τη δράση τους μέσω των υποδοχέων τους (ERα, ERβ) οι οποίοι αποτελούν μέλη μιας υπεροικογένειας μεταγραφικών παραγόντων, των πυρηνικών υποδοχέων. Οι πυρηνικοί υποδοχείς ρυθμίζουν τη γονιδιακή έκφραση μέσω θετικής ή αρνητικής παρεμβάσεως στη δράση άλλων μεταγραφικών παραγόντων, όπως του NFκB, με τη βοήθεια ενός μηχανισμού που ονομάζεται cross-talk. Αν και η φλεγμονή με την καρκινογένεση έχουν αναγνωρισμένη σχέση από παλιά, συνδέθηκαν άμεσα με την παρατήρηση ότι υπερέκφραση του γονιδίου για το ένζυμο κυκλοοξυγενάση-2 (COX-2), αποτελεί πρώιμο γεγονός της καρκινογένεσης (Greten et al, 2004). Η COX-2, όπως επίσης και ο μεταγραφικός παράγοντας NFκB, που σχετίζεται με τη φλεγμονή, έχει διαπιστωθεί ότι συμμετέχουν στις διαδικασίες της καρκινογένεσης.. Η σύνδεση των οιστρογόνων στους οιστρογόνικους υποδοχείς επάγει τη δέσμευση συν-ρυθμιστικών παραγόντων, οι οποίοι διακρίνονται σε δύο μεγάλες κατηγορίες τους συν-ενεργοποιητές (coactivators), όπως p300 και τους συν-καταστολείς (corepressors), όπως NCoR. Κατά την παρούσα εργασία μελετήθηκε η μεμονωμένη όσο και η συνδυαστική έκφραση των πέντε παραπάνω μορίων στο φυσιολογικό επιθήλιο και στα καρκινώματα διαφόρων Grade, σε ιστικά δείγματα από 140 ασθενείς που υποβλήθηκαν σε διαγνωστική βιοψία διουρηθρική εκτομή νεοπλάσματος κύστεως ή ριζική κυστεκομή. Η μέθοδος που εφαρμόστηκε ήταν η ανοϊστοχημεία σε τομές παραφίνης, η οποία λόγω του μορφολογικού της χαρακτήρα επέτρεψε τη λήψη δεδομένων για τη σχετική εντόπιση των μορίων στους ενδοκυττάριους χώρους, τις ενδοεπιθηλιακές στιβάδες, τις φυσιολογικές ή παθολογικές ιστολογικές βαθμίδες και το επιθηλιακό ή μεσεγχυματικό διαμέρισμα. Ο παράγοντας NFκB (υπομονάδα p65) εμφάνισε μεικτή υποκυττάρια εντόπιση. Στην παρούσα ανοσοϊστοχημική μελέτη το επίπεδο της έκφρασης του NFκB στον πυρήνα των καρκινικών κυττάρων παρουσίαζε μια στατιστικά σημαντική συνολική αύξηση στα τρία επίπεδα διαφοροποίησης των καρκινωμάτων. Τα καρκινώματα χαμηλής διαφοροποίησης παρουσίαζαν ισχυρότερη ανοσοθετικότητα του NFκB από τα μετρίας και καλής διαφοροποίησης. Η αύξηση της πυρηνικής εντόπισης του NFκB συνδυάζεται με ταυτόχρονη ελάττωση της κυτταροπλασματικής, γεγονός που επιβεβαιώνει τη βιολογική δράση του. Ο πυρηνικός υποδοχέας ERβ, που εντοπίζεται στο πυρήνα των καλώς διαφοροποιημένων καρκινικών κυττάρων, είναι στατιστικά σημαντικά αυξημένος σε σχέση με λιγότερο διαφοροποιημένα νεοπλασματικά κύτταρα. Στην παρούσα ανοσοϊστοχημική μελέτη τα κύτταρα του φυσιολογικού επιθηλίου της ουροδόχου κύστης, εκφράζουν έντονα τον πυρηνικό υποδοχέα και κατά την πρόοδο της καρκινογένεσης η έκφραση του ελαττώνεται, παράλληλα με την απώλεια της διαφοροποίησης των καρκινικών κυττάρων. Στην εξέλιξη της καρκινογένεσης, η COX-2 επάγεται σταθερά, σύμφωνα με τα αποτελέσματα της παρούσας εργασίας, με διαδοχικές αυξήσεις που συνοδεύουν όλα τα στάδια της προοδευτικής αποδιαφοροποίησης των κυττάρων. Η πυρηνική έκφραση του p300 αυξάνεται σταδιακά καθώς τα καρκινώματα αποκτούν χαρακτήρες αποδιαφοροποίησης, συσχέτιση στατιστικώς σημαντική. Η πυρηνική έκφραση του NCoR ελαττώνεται σταδιακά καθώς τα καρκινώματα αποκτούν χαρακτήρες αποδιαφοροποίησης, συσχέτιση στατιστικώς σημαντική, σύμφωνα με τα ευρήματα της παρούσας μελέτης. Στις υπόλοιπες συσχετίσεις μελετήθηκε η συν-έκφραση πλέον των παραγόντων σε κάθε ασθενή, με σκοπό την εξαγωγή συμπερασμάτων για ενδεχόμενη αλληλεπίδραση τους. Αναλυτικότερα, παρατηρήθηκε στα καρκινώματα της ουροδόχου κύστεως ισχυρή θετική συσχέτιση του NFκB με την έκφραση της COX-2, υποδηλώνοντας τον υποστηρικτικό ρόλο των δύο αυτών παραγόντων στην πρόοδο της καρκινογένεσης. Από τη συσχέτιση NFκB και ERβ προέκυψε κατασταλτική επίδραση του πρώτου στην ογκοανασταλτική δράση του δεύτερου, υποδηλώνοντας σχέση ανταγωνισμού στη δέσμευση συνπαραγόντων και κατάληψης ίδιων περιοχών στους υποκινητές γονιδίων, ενώ δεν αναδείχθηκε συνομιλία ανάμεσα στον ERβ και COX-2. Τέλος αποκαλύφθηκε συνεργική δράση του NFκB με τον p300 στην καρκινογένεση, με τον ERβ και NCoR να χάνουν την ικανότητα πρόκλησης κυτταρικής διαφοροποίησης και άρα την προστατευτική επίδρασή τους. Η έκφραση του ERβ συσχετίστηκε με την ιστοπαθολογική βαρύτητα, ανά βαθμό έκφρασης των συνρυθμιστών p300 και NCoR, ώστε να διευκρινιστεί εάν η συγκέντρωση τους στα κύτταρα είναι καθοριστικός παράγοντας για την επίδραση του πυρηνικού υποδοχέα στον ιστολογικό φαινότυπο. Η επεξεργασία των δεδομένων φανερώνει αρνητική συσχέτιση της προόδου της καρκινογένεσης με την πυρηνική έκφραση του ERβ, αλλά μόνο όταν τα κύτταρα υπερεκφράζουν παράλληλα τον p300. Η απώλεια της έκφρασης του NCoR αναστέλλει την ενεργοποίηση του πυρηνικού υποδοχέα ERβ, γεγονός που διαπιστώθηκε και στην παρούσα μελέτη κατά τη διάρκεια της απώλεια διαφοροποίησης των καρκινικών κυττάρων της ουροδόχου κύστης. Επομένως, το τελικό αποτέλεσμα της δράσης του ERβ εξαρτάται από τον ανταγωνισμό των ενεργοποιητών και καταστολέων για τις ίδιες θέσεις σύνδεσης στο μόριο του ERβ. Συνολικά, η χρήση αγωνιστών των ERβ και NCoR με παράλληλη αναστολή των NFκB, COX2 και NCoR, θα είχε πιθανότατα ευνοϊκό αποτέλεσμα στην αναστροφή της καρκινογένεσης στην ουροδόχο κύστη. Ειδικές παράμετροι του χημειοπροληπτικού σχήματος, θα ήταν ωφέλιμο να τροποποιούνται ύστερα από εξατομικευμένη αξιολόγηση του δικτύου των πέντε παραγόντων. / Backround Bladder cancer is the forth most common malignancy among men in the Western World, following prostate, lung, and colon cancer. However, due to the highly recurrent nature of the disease, bladder cancer is the most prevalent and the most expensive per patient treated. Carcinogenesis is a complicated multistage process that gradually deprives normal cells of their natural phenotype, resulting in tissue disturbance, from which tumors finally emerge. During its lengthy course it is accompanied by an evenly prolonged inflammatory response. Chemoprevention pursues the arrest of both processes, by means of pharmacological targetting key molecules, involved in cell growth, differentiation and apoptosis, as well as in chronic inflammation. Nuclear Hormone Receptors are appropriate targets, as they are induced by ligand binding to mediate gene transcription. Epidemiological and molecular data support the possible role of ERβ and NFκB between the two collateral processes, providing evidence for target-specific chemopreventive strategies. ERβ promotes cellular differentiation and restriction of inflammation. Nuclear receptor coregulators provide a great level of sophistication in the dynamic process of transcriptional regulation. The transcriptional coactivator p300 is a ubiquitous nuclear protein and transcriptional cofactor with intrinsic acetyltransferase activity. NCoR is a protein that contain distinct functional domains responsible for interaction with NRs, and activation of HDAC proteins, ultimately resulting in targeted repression of transcription The inducible transcription factor NF-κB, immediately after being released from a cytoplasmic inhibitor, translocates into nucleus, where it enhances transcription of anti-apoptotic and pro-inflammatory genes. COX-2, an enzyme often induced in neoplastic conditions, perpetuates the chronic inflammatory state in the epithelium and its microenvironment, by means of prostaglandin synthesis. Elucidation of the molecular networks implicated in estrogen signaling is very important in view of the potential use of selective estrogen receptor modulators in chemoprevention and targeted anticancer therapy. Materials and Methods. In our retrospective study we included 111 consecutive patients (74 males and 37 females), aged 23-90 years (mean 70±10) diagnosed with TCC of the bladder by either biopsies, transurethral resection of bladder tumor, or radical cystectomies, between 2000 and 2002 from the Urological Department of Urology of University Hospital of Patras, Greece. None of the patients had received any preoperative intravesical therapy. Bladder tumors were graded and staged according to the World Health Organization (WHO) grading. Paraffin section immunohistochemistry was utilized and relative expression was estimated in intracellular compartments, intraepithelial layers, and histologic categories. NF-κB(p65 subunit) demonstrated mixed subcellular presence, COX2 cytoplasmic whereas ERβ, p300 and NCoR staining patterns were nuclear. NF-κB and COX-2, were constantly upregulated as tumorigenesis progressed. Results NF-κB, COX-2 and p300 expression correlated positively with progression of carcinogenesis, suggesting a potential involvement in bladder tumorigenesis. On the contrary, ERβ and NCoR were severely diminished in cancer, compared to normal epithelium, and they were affected by tumor Grade. The remaining correlations are based on coexpression analysis of the aforementioned factors, individually for each patient, to permit judgement of molecular interactions. In detail, an inverse staining between ERβ and nuclear p65 immunoreactivity was observed and we could suggest that there is a reciprocal transactivation between ERβ and activated NFκB. COX-2 was positively associated in bladder carcinomas with NFκB, a finding which may denote the nuclear factor contribution to the enzyme induction. A correlation has been established, when correlating the expression of ERβ with the coregulators, positive with NCoR and negative with p300, indicating a potential role of these key molecules in bladder carcinogenesis. Furthermore, p300 and NCoR, may not be strictly segregated and in bladder cancer cells interact directly, since, according to biochemical purification studies, p300 is capable of directed negative interaction with NCoR. Conclusions The inhibition of ERβ in combination with the antiapoptotic properties of NFκB may contribute to the pathogenesis of TCC. Selective ERβ and NCoR agonist and agents-inhibitors of NFκB, COX2 and p300 may represent a possible new treatment strategy, by virtue of their role in bladder carcinogenesis. Subtle variations in the chemopreventive regimen, based on personalized molecular profiling, would hopefully achieve a patient-tailored therapeutic approach.

Submitted by Adriana Ávila de Almeida null (celdrica2003@yahoo.com.br) on 2018-03-23T16:45:45Z No. of bitstreams: 1 Tese Final - Adriana Ávila de Almeida.pdf: 2506211 bytes, checksum: e38a3f026d55d541be0fd2ec9142a2a2 (MD5) / Approved for entry into archive by Silvana Alvarez null (silvana@ict.unesp.br) on 2018-04-03T21:06:34Z (GMT) No. of bitstreams: 1 almeida_aa_dr.sjc.pdf: 2506211 bytes, checksum: e38a3f026d55d541be0fd2ec9142a2a2 (MD5) / Made available in DSpace on 2018-04-03T21:06:34Z (GMT). No. of bitstreams: 1 almeida_aa_dr.sjc.pdf: 2506211 bytes, checksum: e38a3f026d55d541be0fd2ec9142a2a2 (MD5) Previous issue date: 2018-02-05 / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Os carcinógenos do tabaco estão relacionados a diversos tipos de câncer incluindo o carcinoma de células escamosas (CCE) bucal. Aliado ao álcool, o tabaco contribui para o desfecho desfavorável destes casos. A susceptibilidade individual ao câncer pode estar relacionada a expressão das enzimas que metabolizam tais carcinógenos. O objetivo deste trabalho é avaliar a expressão dos genes CYP1A1, CYP1B1, CYP2A6 e CYP2E1 no CCE bucal por meio de qPCR. Foram coletadas amostras de 32 indivíduos com CCE e de 15 controles submetidos a cirurgias bucais por lesões benignas. Foram constituídos quatro grupos: Grupo CCE fumante (n=26), Grupo CCE não fumante (n=6), Grupo controle fumante (n=9) e Grupo controle não fumante (n=6). O Teste de Fagerström para Dependência a Cigarros (TFDC) foi usado para avaliar a dependência nicotínica (DN) e AUDIT para avaliação do consumo de etílicos. Houve diminuição da expressão do gene CYP1B1 nos casos de CCE comparados aos controles. Foram encontradas diferenças estaticamente significativas de expressão gênica de CYP1B1 entre os Grupos CCE fumante e controle fumante (p=0,0018), Grupo CCE não fumante e controle não fumante (p=0,0079) e CCE fumante com CCE não fumante (p=0,0385) e entre os quatro grupos (p<0,0001). Houve diminuição da expressão do CYP2A6 no Grupo CCE fumante em relação ao Grupo controle, mas apenas um paciente do Grupo controle expressou este gene. Houve aumento da expressão de CYP2E1 entre os Grupos CCE fumante e controle fumante (p=0,0424). Concluindo, foi encontrada grande variabilidade interindividual no estudo da expressão dos genes estudados. Houve maior expressão de CYP1A1 e CYP2E1 em amostras de indivíduos fumantes com CCE. Os genes CYP1B1 e CYP2A6 estavam menos expressos no Grupo CCE fumante em relação ao Grupo controle. Para os genes CYP1B1 e CYP2E1 foram encontrados valores significativos na correlação entre a expressão gênica e parâmetros demográficos e de perfil tabágico no Grupo controle fumante, e do AUDIT no Grupo CCE não fumante. O gene CYP2E1, além de estar relacionado ao metabolismo do álcool, também deve ser considerado importante marcador do metabolismo dos carcinógenos derivados do tabaco. / Tobacco carcinogens are related to various types of cancer, including oral squamous cell carcinoma (OSCC). Allied to alcohol, tobacco contributes to the unfavorable outcome of the cases. Individual cancer susceptibility may be related to an expression of the enzymes that metabolize such carcinogens. The aim of this work is to evaluate the expression of the genes CYP1A1, CYP1B1, CYP2A6 and CYP2E1 on OSCC by qPCR. Samples were collected from 32 individuals with OSCC and 15 controls submitted to oral surgeries due to benign lesions. There were four groups: Smoker SCC group (n = 26), nonsmoker SCC group (n = 6), Smoker control group (n = 9) and nonsmoker control group (n = 6). The Fagerström Test for Cigarette Dependence (TFCD) was used to evaluate nicotinic dependence (ND) and AUDIT for the evaluation of alcohol consumption. There was a decrease in CYP1B1 gene expression in cases of SCC compared to controls. (P = 0.0018); smoker CCE and non-smoker control (p = 0.0079); smoker SCC with nonsmoker SCC (p = 0.0385) and between the four groups (p <0.0001). There was a decreased expression in CYP2A6 in the smoker SCC Group compared to the control group, but only one control group patient expressed this gene. There was an increased expression of CYP2E1 between the smoking and nonsmoking SCC groups (p = 0.0424). In conclusion, large interindividual variability was found in the study of the expression of the genes studied. There was greater expression of CYP1A1 and CYP2E1 in samples from smokers with SCC. The CYP1B1 and CYP2A6 genes were less expressed in the smoker SCC Group. Significant values were found for the CYP1B1 and CYP2E1 genes in the correlation between a gene expression and a parameter and a non-smoker control group, non-smoker control group and AUDIT. The CYP2E1 gene, besides being related to alcohol metabolism, should also be considered an important marker of the metabolism of the carcinogens derived from tobacco. / 2016/08633-0

Enquanto lesões cutâneas do líquen plano (LP) são autolimitantes, suas manifestações orais (LPO) têm comportamento crônico, raramente apresentam remissão espontânea, e podem sofrer transformação maligna, embora subsista controvérsia sobre esta ultima questão. A este respeito, alguns autores têm dado ênfase ao envolvimento da Candida spp. na malignização LPO devido à capacidade deste fungo em produzir enzima carcinogênica N-nitrobenzilmetilamina e sua relativa freqüência em lesões LPO. Adicionalmente, foi investigada a xerostomia que, além de ocorrer com maior freqüência em indivíduos da faixa etária em que o LPO é mais prevalente, é considerado fator predisponente à candidose. Portanto, a correlação entre xerostomia e colonização por Candida spp. apresente relevância de ser investigada. O presente estudo objetivou comparar a prevalência de Candida spp. e xerostomia em 37 pacientes com lesões LPO (grupo LPO) com a de 26 pacientes com lesões inflamatórias não-LPO (grupo não-LPO) e com a de 28 indivíduos sem lesões orais (grupo controle-saudável). Pacientes LPO foram predominantemente indivíduos do sexo feminino com média idade de 50 anos. Presença de xerostomia foi evidenciada em 35,1% dos pacientes do grupo LPO, em 38,5% do grupo não-LPO e em 25% do grupo controle-saudável, não havendo diferença estatisticamente significante entre os três grupos (p > 0,05). Nos três grupos, medicação sistêmica e presença de distúrbios emocionais (ansiedade e depressão) não foram estatisticamente significante associados como fatores ao desenvolvimento de xerostomia (p > 0,05). A presença de xerostomia não foi fator estatisticamente significante de predisposição à colonização por Candida spp. nos três grupos. Colonização por Candida spp foi maior no grupo controle-saudável (53,5%) que nos outros grupos (29,7% no LPO e 26,9% no não-LPO), porém, não houve diferença estatisticamente significante (p > 0,05). Formas clínicas do LPO não foram fatores de predisposição à colonização por Candida spp. Espécie mais freqüentemente isolada nos três grupos foi Candida albicans. Formas não-albicans, especificamente a C. dubliniensis, foram encontradas em três indivíduos do grupo controle-saudável. / While cutaneous lesions of lichen planus (LP) are self-limiting, its counterpart oral manifestations (OLP) are chronic, hardly ever undergo spontaneous remission, and may suffer malignant transformation, though this latter issue still bears some controversy. In this respect, some authors have believed that Candida spp. might play a part in the OLP process of malignant transformation since this fungi has the ability to produce carcinogenic N-nitrobenzilmetilamina enzyme and has been found in OLP lesions. Apart that, xerostomia is considered a predisposing factor to candidosis and occurs more frequently in individuals at an aging in which OLP is more prevalent. Therefore, the correlation between xerostomia and candidosis may be worth it investigating. This study aimed at comparing the prevalence of Candida spp. and xerostomia in 37 patients with OLP lesions (OLP group) with that of 26 patients with inflammatory non-OLP disease (non-OLP group) and with that of 28 subjects without oral mucosal lesions (healthy-control group). OLP patients occurred predominantly in females at a mean age of 50 years. Presence of xerostomia was seen in 35.1% of patients in the OLP group, in 38.5% of the non-OLP and in 25% of the healthy-control group with no statistically significant difference among the three groups (p > 0.05). In all the groups, systemic medication and the presence of psychological disorder (anxiety and depression) were not statistically significant factors associated with the development of xerostomia. The presence of xerostomia was not a statistically significant factor at predisposing the colonization by Candida spp. in the three groups (p > 0.05). Colonization by Candida species was higher in healthy-control group (53.5%) than in other groups (29.7% in OLP and 26.9% in non- LPO), but the difference among them did not reach a statistical significance (p > 0. 05). Clinical forms of OLP were not predisposing factors to the colonization by Candida spp. The most frequently isolated species in the three groups were Candida albicans. Non-albicans forms, specifically C. dubliniensis, was found in three patients in the healthy-control group.

O isoprenóide geraniol (GO) apresentou atividade quimiopreventiva quando administrado continuamente durante as fases de iniciação e pós-iniciação em modelo de carcinogênese experimental de cólon por meio da redução do número de focos de criptas aberrantes (FCAs) totais FCAs &#8805; 4 criptas e aumento de apoptose no cólon distal. Dessa forma, optou-se por avaliar os eventuais efeitos de três doses de GO (GO1: 25mg/100g de peso corpóreo [p.c.], G02: 50 mg/100g de p.c. e G03: 100 mg/100g de p.c.) em categorias de lesões pré-neoplásicas (LPNs) induzidas por dimetilhidrazina (DMH) durante a fase de pós-iniciação tardia de modelo de carcinogênese experimental de cólon, caracterizada por apresentar lesões mais avançadas e com alto grau de alterações celulares morfológicas, bioquímicas e moleculares denominadas de displasia. Para isso, analisamos diferentes biomarcadores como: FCAs totais e FCAs < ou &#8805; 4 criptas em cólons corados com azul de metileno; focos depletados ou positivos de mucina (FPMs ou FDMs) em cólons corados com azul de toluidina; FCAs convencionais ou displásicos por meio de análise histopatológica em cortes corados com hematoxilina e eosina (HE) e focos positivos ou negativos para beta-catenina (FPBCs ou FNBCs) citoplasmática e/ou nuclear por meio de imunoistoquímica. Além disso, células apoptóticas foram identificadas utilizando-se critérios morfológicos clássicos em FCAs &#8805; 4 no cólon distaI e a expressão de genes envolvidos na carcinogênese de cólon foi avaliada por meio de RT-PCR: HMGCoA-redutase na mucosa colônica e K-Ras e c-myc em FCAs microdissecados. Em relação ao grupo controle, foi possível observar que o grupo tratado com a maior dose de GO (G03) reduziu a freqüência de FCAs &#8805; 4 criptas e FDMs, além de aumentar a apoptose em FCAs &#8805; 4 displásicos no cólon distaI (p &#8804; 0,05). Já, em relação aos outros biomarcadores e às expressões de HMGCoA-redutase, K-Ras e c-myc não observamos diferenças estatísticas entre os tratamentos (p > 0,05). A partir desses resultados, podemos concluir que a dose de 100 mg/100 g de p.c. de GO mostrou ser mais interessante do ponto de vista quimiopreventivo com efeitos observados principalmente no cólon distaI, onde há maiores relatos de incidência de adenocarcinomas colônicos, tanto em animais quanto em humanos. Assim, a indução da morte celular programada em FCAs &#8805; 4 preferencialmente displásicos poderia representar um mecanismo importante de atuação de G03 na redução da freqüência de FCAs &#8805; 4 criptas e de FDMs (também utilizado como marcador de displasia) durante a fase de pós-iniciação tardia de modelo de carcinogênese experimental de cólon. / The isoprenoid geraniol (GO) showed chemopreventive activity when administered continuously during the initiation and post-initiation phases in an experimental model of colon carcinogenesis by reducing the number of total aberrant crypt foci (ACF) and ACFs &#8805; 4 crypts, as well as increasing apoptosis in the distal colon. We therefore chose to evaluate the effects of three different doses of GO (GO1: 25 mg/100 g body weight [b.w.], GO2: 50 mg/100 g b.w. and GO3: 100 mg/100 g of b.w.) on preneoplastic lesions (PNLs) induced by dimethylhydrazine (DMH) during late post-initiation in an experimental model of colon carcinogenesis that is characterized by more advanced lesions and a higher degree of cellular alterations morphological, biochemical and molecular (dysplasia) than previous models. For this study, we analyzed the following biomarkers: total ACFs, ACFs < 4 crypts, and ACFs &#8805; 4 erypts in colons stained with methylene blue; mucin-depleted or mucin-positive foci (MDFs or MPFs) in colons stained with toluidine blue; ACFs, through conventional or dysplastie histopathological analysis of sections stained with hematoxylin and eosin (HE); and cytoplasmic vs. nuclear foci reactivity for beta-catenin (foci positive for beta-eatenin (FPBC) or foci negative for beta catenin (FNBC)) using immunohistochemistry. Additionally, apoptotic cells were identified using classical morphologic criteria in ACFs &#8805; 4 crypts in the distal colon, and the expression of several genes involved in colon carcinogenesis was assessed by RT-PCR, including HMG-CoA reductase in the colonic mucosa and K-Ras and c-myc in microdissected ACFs. Relative to the control group, we observed that the group receiving the highest dose of GO (GO3 group) had a reduced frequency of both ACFs &#8805; 4 crypts and MDFs and that apoptosis increased in dysplastic ACFs &#8805; 4 crypts in the distal colon (p < 0, 05). Expression of HMG-CoA reductase, K-Ras and c-myc did not differ between treatments (p > 0, 05). Based on these results, we conclude that the 100 mg/100 g b.w. dose of GO is the most promising, as it shows evidence of chemopreventive effects mainly in the distal colon, which is a region that is reported to have a higher incidence of colonic adenocarcinomas, both in animaIs and in humans. lnduction of programmed cell death by GO3 in ACFs &#8805; 4 specifically dysplastic could represent an important mechanism of action in reducing the frequency of both ACFs &#8805; 4 crypts and MDFs during late post-initiation in this experimental model of colon carcinogenesis.

Le séquençage de nombreux génomes eucaryotes indique que l’augmentation de la «biocomplexité» au cours de l’évolution n’est pas directement corrélée à l’accroissement du nombre de gènes. En d’autres termes, nous sommes plus que la somme de nos gènes et l’ère post-génomique actuelle promet de cerner de façon plus précise les bases moléculaires de notre identité. A cet égard, il semble de plus en plus clair que l’épigénétique est riche d’une information qui se superpose à celle du code génétique. L’information épigénétique est principalement véhiculée par des modifications de l’ADN et des histones. La modification majeure de l’ADN est la méthylation de la cytosine qui est la marque d’une chromatine transcriptionnellement silencieuse. Quant aux histones, différentes modifications posttraductionnelles ont été décrites, comme l’acétylation, la phosphorylation, la méthylation et l’ubiquitinylation. L’ensemble de ces modifications constituerait un «code histone», dont le décryptage n’en est qu’à ses prémices, permettant d’associer à chaque combinaison de modifications un état particulier de la chromatine, et ainsi de l’expression génique. La méthylation des histones a longtemps été considérée comme irréversible mais l'identification récente de déméthylases des histones spécifiques de certains sites a révélé que cette modification est régulée de façon dynamique et réversible. La découverte de ces enzymes a ouvert de nouveaux axes de recherche dans le domaine de l'épigénétique (Klose and Zhang, 2007). <p><p>Au cours de ma thèse de doctorat, nous nous sommes intéressés à la déméthylase PADI4 (peptidylarginine déiminase 4) qui convertit des résidus arginines des histones H3 et H4, associés à l'activation des gènes, en résidus citrullines, ce qui a pour conséquence d'entraîner une répression transcriptionnelle. Cette réaction porte le nom plus particulier de déimination/citrullination des histones. A l’heure actuelle, il est primordial de cerner comment la déméthylation des histones, et plus précisément la peptidylarginine deiminase 4 (PADI4), réprime la transcription. <p><p>Dans un premier temps, nous avons mis en évidence un lien mécanistique entre la deméthylation et la désacétylation des histones. Nous avons montré que PADI4 interagit avec l’histone désacétylase HDAC1. Cette enzyme est responsable du décrochage des groupements acétyls des histones, conduisant à la fermeture de la chromatine. Des expériences d’immunoprécipitation de la chromatine indiquent que PADI4 et HDAC1 s’associent au promoteur du gène de réponse aux oetrogènes pS2 simultanément et de manière cyclique. L’utilisation d’une construction shRNA dirigée contre la protéine endogène HDAC1 indique que la liaison de PADI4 au promoteur du gène pS2 est dépendante de la présence de HDAC1.<p><p>Dans la deuxième partie de notre travail, un lien mécanistique entre la déméthylation des histones par PADI4 et la méthylation de l’ADN a été mis en évidence. La méthylation de l’ADN est catalysée par des enzymes, appelées méthyltransférases de l’ADN (DNMTs), qui transfèrent des résidus méthyls sur les cytosines. Nous avons montré que la protéine DNMT3A interagit avec PADI4. Nous avons également démontré que l’enzyme PADI4 était capable de citrulliner/déiminer (convertir des résidus arginines en résidus citrullines) la méthyltransférase de l’ADN DNMT3A in vitro et que cette citrullination de la protéine DNMT3A par PADI4 stabiliserait DNMT3A in vivo.<p><p>Enfin, nos récents travaux révèlent une relation mécanistique entre la protéine MeCP2, interprète des signaux de méthylation de l’ADN, et la protéine polycomb EZH2. Celle-ci possède une activité méthyltransférase d’histone sur les lysines 27 de l’histone H3. Nos données montrent que MeCP2 interagit avec EZH2 et que ces protéines fixent des régions promotrices communes. De plus, la déplétion en MeCP2 affecte la présence de EZH2 au niveau de ces régions communes.<p><p>En conclusion, ce travail de thèse devrait permettre une meilleure compréhension des mécanismes moléculaires de l’épigénétique. Plus particulièrement, il devrait aider à mieux cerner comment la première histone déméthylase décrite, la peptidylarginine déiminase 4 ou PADI4, verrouille l’expression génique.<p> / Doctorat en Sciences biomédicales et pharmaceutiques / info:eu-repo/semantics/nonPublished

L’Homme est exposé tout au long de sa vie à de nombreux contaminants présents dans l’environnement et l’alimentation généralement à faibles doses et en mélanges. L’évaluation des risques pose problème dans la mesure où il est bien établi qu’il existe des différences de réponse entre l’homme et l’animal. Quelle que soit la voie d’exposition, de par son rôle majeur dans la biotransformation des xénobiotiques, le foie est considéré comme un organe cible pour de nombreuses classes de produits chimiques potentiellement cytotoxiques, génotoxiques voire cancérogènes. Nous avons utilisé la lignée de cellules hépatiques humaines HepaRG non transformées pour évaluer la toxicité chronique et/ou le pouvoir cancérogène de pesticides et de composés génotoxiques présents dans l’environnement. Cette lignée est la seule connue pour avoir conservé des propriétés proches des hépatocytes humains en culture primaire. Dans une première partie nous avons confirmé le maintien de ses capacités fonctionnelles à confluence par l’analyse du transcriptome et de la biocinétique de 4 médicaments, après traitements quotidiens pendant 14 jours. Nous avons ensuite recherché les effets de mélanges de pesticides après des expositions aiguës et répétées. Nous avons ainsi montré que : 1. l’isomalathion, une impureté majeure du malathion, joue un rôle prépondérant sur la toxicité hépatique de ce dernier et qu’il inhibe la carboxylesterase impliquée dans le métabolisme des deux composés; 2. l’endosulfan et le méthoxychlore, deux organochlorés métabolisés par les CYP3A4 et 2B6, agissent de manière synergique sur leur cytotoxicité après une exposition unique ou répétée. De plus, alors que l'activité du CYP3A4 est inhibée de manière réversible par l’endosulfan, le méthoxychlore l’augmente. En revanche, l’activité du CYP2B6 est induite par les deux pesticides. Lorsqu’ils sont en mélange équimolaire un effet additif ou antagoniste est observé sur l'activité du CYP3A4 et du CYP2B6 respectivement quelle que soit la durée de l’exposition. Enfin, dans une troisième partie, nous avons exposé des cellules HepaRG pendant une quinzaine de passages à de faibles doses de deux contaminants génotoxiques nécessitant une bioactivation, l’aflatoxine B1 et une amine aromatique hétérocyclique, le PhiP, et démontré l’acquisition de propriétés de cellules transformées (par exemple croissance sur agar, migration dans le test de griffure et surexpression de gènes associés au cancer). Au total, nos résultats démontrent tout l’intérêt que représente la lignée hépatique humaine HepaRG métaboliquement compétentes pour l’étude de la toxicité chronique et/ou le potentiel cancérogène des contaminants de l’environnement. Ils ont permis de mettre en évidence d’interactions entre des pesticides en mélanges binaires et pour la première fois d’analyser le potentiel cancérogène de contaminants génotoxiques dans une lignée hépatique humaine. / Humans are exposed throughout their life to many environmental and food contaminants, usually at low doses and in mixtures. Risk assessment remains questionable as it is well established that there are differences in the response to chemicals between humans and animals. Regardless of the route of exposure, due to its major role in xenobiotic biotransformation, the liver is considered as a target organ for many classes of chemicals potentially cytotoxic, genotoxic or carcinogenic. We used the HepaRG cell line to evaluate chronic toxicity and/or carcinogenicity of pesticides and genotoxic compounds. This cell line is the only one known to exhibit properties similar to those of human hepatocytes in primary culture. In the first part we confirmed the maintenance of functional capacities of these cells at confluence by transcriptomic and biokinetic analysis of several drugs after a 14-day treatment. We then investigated the effects of mixtures of pesticides after acute and repeated exposures. We showed that : 1. Isomalathion, a major impurity of malathion, played a leading role on liver toxicity and inhibited carboxylesterase that is involved in the metabolism of these two compounds; 2. Endosulfan and methoxychlor, two organochlorines, metabolized by CYP3A4 and CYP2B6, acted synergistically on their cytotoxicity after single or repeated exposure. Moreover, whereas activity of CYP3A4 was reversibly inhibited by endosulfan and increased by methoxychlor. By contrast, CYP2B6 activity was induced by these two pesticides while in equimolar mixtures, they caused additive or antagonistic effects on CYP3A4 and CYP2B6 activities respectively, regardless of the duration of exposure. Finally, in the third part, we exposed HepaRG cells for up to 15 passages to low doses of two genotoxic contaminants which required bioactivation, aflatoxin B1 and heterocyclic aromatic amine, PhIP, and demonstrated the appearance of properties of transformed cells (e.g. growth on agar, cell migration in the wound healing test and overexpression of a number of genes associated with cancer). Altogether, our results demonstrate the great potential interest that represents the metabolically competent human liver cell line HepaRG for the study of chronic toxicity and/or carcinogenic potential of environmental contaminants. They highlight possible interactions between pesticides in binary mixtures and for the first time, demonstrate that the carcinogenic potential of genotoxic contaminants can be analyzed in an human hepatic cell line.