Em diversos casos, o câncer bucal é precedido por lesões pré-malignas, como por exemplo, a leucoplasia, sendo que o tabaco é um fator de risco. No entanto, apesar deste potencial negativo, há estudos limitados em fumantes e não fumantes sobre o desenvolvimento de displasia para carcinoma. Sabe-se que o principal componente do factor de transcrição AP-1, a proteína c-Jun e a sua forma fosforilada (p-c-Jun), participam do ciclo celular e que sua inibição compromete a proliferação celular. A proteína p27 tem sido demonstrada como inibidora de quinase, e sabe-se que tem sua expressão diminuída durante a carcinogênese. A expressão diminuída de p27 tem sido relacionada a um pior prognóstico em carcinoma epidermóide. O objetivo deste estudo foi verificar a expressão das proteínas c-Jun, p-c-Jun e p27, em lesões potencialmente malignas diagnosticadas clinicamente como leucoplasia de pacientes fumantes e não fumantes. Foram selecionados 73 casos diagnosticados clinicamente como leucoplasias, os quais foram divididos nos seguintes grupos: leucoplasia com e sem displasia epitelial, e entre fumantes e não fumantes (perfazendo 4 grupos). Cortes histológicos das lesões foram classificados segundo o sistema de graduação binário, e subsequentemente submetidos à técnica imunohistoquímica da estreptoavidina-biotina. Avaliou-se também a associação da proliferação celular pela c-Jun, p-c-Jun e p27 com o tabagismo, presença e ausência de displasia, localização e gênero. O presente estudo verificou que ocorrência de displasia epitelial em baixo e alto risco não teve associação com o hábito de fumar do paciente (p= 0,5430). Avaliando apenas a imunorreatividade das proteínas c-Jun, p-c-Jun e p27 individualmente observouse que a expressão destas não teve associação com a condição fumante do paciente (p> 0,05). Porém, ao compararmos a imunomarcação de c-Jun e p-c-Jun entre si, no total da amostra (p=0,0448) e somente para displasia em fumantes (p=0,0165), nota-se significativamente menor expressão de p-c-Jun. Comparando c-Jun e p27 nas displasias em não fumantes, houve significativamente maior expressão de c-Jun e menor expressão de p27 (p=0,0079). A análise do Teste binomial de duas proporções revelou que as regiões de língua e assoalho bucal estavam associadas à ocorrência de lesões displásicas quando comparadas a lesões não displásicas (p<0,0001). Concluiu-se que não houve correlação entre fumo e grau de displasia. A expressão das proteínas c-Jun, p-c-Jun e p27 foi independente da condição fumante do paciente. / In Several cases, the oral cancer is preceded by-malignant lesions potentially, such as leukoplakia, and that tobacco is a risk factor. However, despite this negative potential, there are limited studies in smokers and nonsmokers on the development of dysplasia to carcinoma. It is known that the main component of the transcription factor AP-1, c-Jun protein and its phosphorylated form (pc-Jun), participate in cell cycle inhibition and their committed cell proliferation. The p27 protein has been shown to inhibit kinase, and it is known that their expression is decreased during carcinogenesis. The decreased expression of p27 has been linked to poor prognosis in squamous cell carcinoma. The aim of this study was to evaluate the expression of proteins c-Jun, pc-Jun and p27 in potentially malignant lesions from smokers and non-smokers, diagnosed clinically as leukoplakiaa in smokers and nonsmokers. We selected 73 cases diagnosed clinically as leukoplakia, which were divided into the following groups: leukoplakia with and without dysplasia, and between smokers and nonsmokers (totaling 4 groups). Histological lesions were classified according to the binary grading system, and subsequently subjected to immunohistochemistry technique streptavidin-biotin. We also evaluated the association of cell proliferation of c-Jun, pc-Jun and p27 with smoking, presence and absence of dysplasia, location and gender. This study found that the occurrence of epithelial dysplasia in low-and high-risk had no association with the patient\'s smoking habit (p = 0,5430). When evaluating the immunoreactivity of the proteins c-Jun, p27 and pc-Jun alone it was observed that the expression of them was also independent of the condition of the patient smoking (p> 0,05). However, when comparing the immunostaining of c-Jun and pc-Jun together, for the total sample (p = 0,0448) and only for dysplasia in smokers (p = 0,0165), there was significantly lower expression of pc-Jun. Comparing p27 and c-Jun in dysplasias in nonsmokers, there was significantly higher expression of c-Jun and reduced expression of p27 (p = 0,0079). The analysis of two binomial proportions test revealed that the lesions in the tongue and floor of the mouth were more prone to be dysplastic (p <0.0001). It was concluded that there was no correlation between smoking and degree of dysplasia. The expression of c-Jun, p27 and pc-Jun proteins was independent of smoking habit of the patient. The anatomoclinical aspects combined with the expressions of c-Jun and p27 may assist the pathologist in directing the histopathological diagnosis.

Nierenzellkarzinome (RCC) gehören zu den häufigsten malignen Tumoren weltweit. Aufgrund der alarmierend hohen Inzidenz- und Sterberate besteht ein dringender Bedarf an neuen therapeutischen Targets zur Behandlung von RCCs. Punktmutationen in der Codesequenz von Proteinen führen zu einer Anhäufung von fehlgefalteten Proteinen in Tumorzellen und erfordern eine stärkere Kontrolle der Proteinqualität. Das Ubiquitin-Proteasome-System (UPS) bietet daher ein ideales therapeutisches Target für die RCC Therapie. Aktuelle Veröffentlichungen deuten auf eine Deregulation des COP9 Signalosome (CSN)-Cullin-RING-Ubiquitin-Ligase-(CRL)-Signalweges hin, einem Bestandteil des UPS. In der vorliegenden Arbeit wurden ausgewählte Komponenten des CSN-CRL Signalweges im RCC Gewebe und in vier RCC Zelllinien untersucht. In immunohistochemischen Studien am klarzelligen RCC-Gewebe konnte keine Hochregulierung einer einzelnen CSN-Untereinheit gezeigt werden. Höchstwahrscheinlich ist der gesamte CSN-Komplex im klarzelligen Nierenkarzinom im Vergleich zu nicht-malignem Nierengewebe stärker exprimiert. Die Untersuchung von vier RCC-Zelllinien zeigte eine interessante Deregulierung der CAND1-Skp2-p27 Achse in einer der Zelllinien. 786-O Zellen wiesen zwei p27Kip1 (p27) Varianten (p27V109G und p27I119T), eine Erhöhung des Skp2 und eine Reduktion des CAND1 Levels auf. Die Expression und Lokalisation von CAND1 wurde weiter in einer größeren RCC-Kohorte untersucht. Dabei zeigte sich eine negative Korrelation zwischen einer hohen zytosolischen CAND1 Expression und dem Gesamtüberleben von Patienten mit klarzelligen renalen Tumoren. Beide p27 Varianten werden durch das UPS abgebaut und binden an das CSN, Skp2, Cdks sowie an Cyclin E. Interessanterweise zeigte die p27 Mutanten beinhaltende Zelllinie 786-O eine höhere Proliferationsrate als die p27-Wildtyp-Zelllinie A498. In einem im Rahmen dieser Arbeit entwickelten Genotypisierungs-Assay konnte eine große RCC-Kohorte nach den beiden p27-Mutanten untersucht werden. In 42,5% der RCC Patienten konnte die Mutante p27V109G heterozygot nachgewiesen werden. Die Präsenz der beiden Mutanten p27V109 und p27I119T im RCC-Gewebe sowie die veränderte Expression von Skp2 und CAND1 machen den CSN-CRL Signalweg zu einem attraktiven therapeutischen Target für die Behandlung von Patienten mit Nierenzellkarzinom. / Renal cell carcinomas (RCC) belong to the most common malignant tumors worldwide. Alarming high incidence and mortality rates elucidate the urgent need for new therapeutic targets in RCCs. Point mutations in protein coding sequences lead to numerous unfolded proteins in cancer cells, requiring effective protein quality control. Therefore, components of the ubiquitin proteasome system (UPS) might be a promising new approach for RCC therapy. Recent publications in renal cancers point to a deregulated COP9 signalosome (CSN)-Cullin-RING Ubiquitin Ligase (CRL) pathway, a segment of the UPS. In the present thesis, selected components of the CSN-CRL pathway were studied in RCC tissues and four RCC cell lines. Immunohistochemistry results did not show an overexpression of a single CSN subunit in clear cell RCC tissues (ccRCC). However, it seems that the CSN holo complex is upregulated in analyzed ccRCCs. Examination of four RCC cell lines revealed a deregulation of the CAND1-Skp2-p27 axis in 786-O cells. These cells harbor two p27Kip1 (p27) mutants (p27V109G and p27I119T), high Skp2 and decreased CAND1 levels. Expression and localization of CAND1 was studied in a larger cohort of RCC tissues and revealed high cytosolic levels of CAND1 to be negatively correlated with overall survival in ccRCC patients. Both p27 variants were found to be degraded by the UPS and bound to the CSN, Skp2, Cdks and cyclin E. Interestingly, 786-O cells appear to grow 3-fold faster than A496 cells expressing p27wt. Further, a large cohort of RCC was screened for both p27 variants using a genotyping assay, specifically designed within the present thesis. 42.5% of the RCC patients harbor p27V109G heterozygously. The occurrence of p27V109G and p27I119T in RCC tissues as well as changed expression of Skp2 and CAND1 make the CSN-CRL pathway an attractive therapeutic target for the treatment of patients with RCC.

Em diversos casos, o câncer bucal é precedido por lesões pré-malignas, como por exemplo, a leucoplasia, sendo que o tabaco é um fator de risco. No entanto, apesar deste potencial negativo, há estudos limitados em fumantes e não fumantes sobre o desenvolvimento de displasia para carcinoma. Sabe-se que o principal componente do factor de transcrição AP-1, a proteína c-Jun e a sua forma fosforilada (p-c-Jun), participam do ciclo celular e que sua inibição compromete a proliferação celular. A proteína p27 tem sido demonstrada como inibidora de quinase, e sabe-se que tem sua expressão diminuída durante a carcinogênese. A expressão diminuída de p27 tem sido relacionada a um pior prognóstico em carcinoma epidermóide. O objetivo deste estudo foi verificar a expressão das proteínas c-Jun, p-c-Jun e p27, em lesões potencialmente malignas diagnosticadas clinicamente como leucoplasia de pacientes fumantes e não fumantes. Foram selecionados 73 casos diagnosticados clinicamente como leucoplasias, os quais foram divididos nos seguintes grupos: leucoplasia com e sem displasia epitelial, e entre fumantes e não fumantes (perfazendo 4 grupos). Cortes histológicos das lesões foram classificados segundo o sistema de graduação binário, e subsequentemente submetidos à técnica imunohistoquímica da estreptoavidina-biotina. Avaliou-se também a associação da proliferação celular pela c-Jun, p-c-Jun e p27 com o tabagismo, presença e ausência de displasia, localização e gênero. O presente estudo verificou que ocorrência de displasia epitelial em baixo e alto risco não teve associação com o hábito de fumar do paciente (p= 0,5430). Avaliando apenas a imunorreatividade das proteínas c-Jun, p-c-Jun e p27 individualmente observouse que a expressão destas não teve associação com a condição fumante do paciente (p> 0,05). Porém, ao compararmos a imunomarcação de c-Jun e p-c-Jun entre si, no total da amostra (p=0,0448) e somente para displasia em fumantes (p=0,0165), nota-se significativamente menor expressão de p-c-Jun. Comparando c-Jun e p27 nas displasias em não fumantes, houve significativamente maior expressão de c-Jun e menor expressão de p27 (p=0,0079). A análise do Teste binomial de duas proporções revelou que as regiões de língua e assoalho bucal estavam associadas à ocorrência de lesões displásicas quando comparadas a lesões não displásicas (p<0,0001). Concluiu-se que não houve correlação entre fumo e grau de displasia. A expressão das proteínas c-Jun, p-c-Jun e p27 foi independente da condição fumante do paciente. / In Several cases, the oral cancer is preceded by-malignant lesions potentially, such as leukoplakia, and that tobacco is a risk factor. However, despite this negative potential, there are limited studies in smokers and nonsmokers on the development of dysplasia to carcinoma. It is known that the main component of the transcription factor AP-1, c-Jun protein and its phosphorylated form (pc-Jun), participate in cell cycle inhibition and their committed cell proliferation. The p27 protein has been shown to inhibit kinase, and it is known that their expression is decreased during carcinogenesis. The decreased expression of p27 has been linked to poor prognosis in squamous cell carcinoma. The aim of this study was to evaluate the expression of proteins c-Jun, pc-Jun and p27 in potentially malignant lesions from smokers and non-smokers, diagnosed clinically as leukoplakiaa in smokers and nonsmokers. We selected 73 cases diagnosed clinically as leukoplakia, which were divided into the following groups: leukoplakia with and without dysplasia, and between smokers and nonsmokers (totaling 4 groups). Histological lesions were classified according to the binary grading system, and subsequently subjected to immunohistochemistry technique streptavidin-biotin. We also evaluated the association of cell proliferation of c-Jun, pc-Jun and p27 with smoking, presence and absence of dysplasia, location and gender. This study found that the occurrence of epithelial dysplasia in low-and high-risk had no association with the patient\'s smoking habit (p = 0,5430). When evaluating the immunoreactivity of the proteins c-Jun, p27 and pc-Jun alone it was observed that the expression of them was also independent of the condition of the patient smoking (p> 0,05). However, when comparing the immunostaining of c-Jun and pc-Jun together, for the total sample (p = 0,0448) and only for dysplasia in smokers (p = 0,0165), there was significantly lower expression of pc-Jun. Comparing p27 and c-Jun in dysplasias in nonsmokers, there was significantly higher expression of c-Jun and reduced expression of p27 (p = 0,0079). The analysis of two binomial proportions test revealed that the lesions in the tongue and floor of the mouth were more prone to be dysplastic (p <0.0001). It was concluded that there was no correlation between smoking and degree of dysplasia. The expression of c-Jun, p27 and pc-Jun proteins was independent of smoking habit of the patient. The anatomoclinical aspects combined with the expressions of c-Jun and p27 may assist the pathologist in directing the histopathological diagnosis.

Les concentrations d’oxygène (O2) dans la moelle osseuse hématopoïétique, sont très inférieures à celle de l’air (20% d’O2) puisqu’elles vont de 4% dans les zones juxta-vasculaires à 0,1% près de l’endoste, où siègent les cellules souches hématopoïétiques (CSH), essentiellement quiescentes. Ce paramètre physiologique, rarement pris en compte, est un élément important dans la régulation de l’hématopoïèse. Les effets bénéfiques des faibles concentrations d’oxygène sur le maintien des cellules souches hématopoïétiques sont maintenant bien établis. Par contre, la réponse du compartiment des progéniteurs aux faibles concentrations d’oxygène est moins examinée mais très discutée, certains montrant une différenciation associée à un blocage de la prolifération alors que d’autres montrent leur disparition de la culture probablement par apoptose. C’est dans ce contexte que se place ces travaux qui visent à approfondir les effets des faibles concentrations en oxygène (de 3 à 0,1%) sur ce compartiment. La culture pendant 72h à 0,1% O2 de la lignée murine de progéniteurs hématopoïétiques non leucémiques FDCP-Mix entraîne leur arrêt progressif en quiescence (Ki-67 négatif) de ces cellules sans induction d’apoptose. Cet arrêt est associé à la différenciation granulocytaire d’une majorité de la population. Dans ces mêmes conditions de culture persiste une population restreinte de cellules qui s¹auto-renouvellent lentement et qui sont capables après repiquage en culture à 20% d’O2 de repeupler une culture liquide et de former des colonies en milieu semi-solide. Ces changements fonctionnels sont associés aux modifications de protéines du cycle cellulaire impliquées dans la quiescence cellulaire : p27KIP1, pRb et CDK. Cette caractérisation permet désormais d’utiliser cette lignée comme modèle pour l’étude des équilibres fondamentaux au maintien de l’homéostasie hématopoïétique. / Oxygen concentrations (O2) in hematopoietic bone marrow vary from 4% in capillaries to less than 0.1% in subendosteum, where hematopoietic where mostly quiescent stem cells reside. This physiological factor, rarely investigated, is an essential piece of hematopoiesis regulation. The beneficial effects of low oxygen concentrations on the maintenance of hematopoietic stem cells are now well established. In contrast, the effects of low O2 concentration on the progenitors compartment, were much less explored and are then more controversial: some articles evidence a pro-differentiative effect related to a cell proliferation blockade while others observe their rapid disappearance from cultures probably due to apoptosis. In this particular context takes place this work which aims to investigate the low oxygen concentration effect (from 3% to 0.1%) on this precise compartment. Culture of the murine non-leukemic hematopoietic progenitor cell line FDCP-Mix line at 0.1% O2 during 72h induces a progressive G0 quiescence blockade (Ki-67 negative) without apoptosis increase. This G0 cell cycle arrest is correlated with the granulo-monocytic differentiation of most cells. In the mean time a minor population of self-renewing cells continues to cycle slowly as evidenced by their 5-FU sensitivity in primary culture and by their capacity to give rise to colonies and to repopulate liquid cultures when replated in cultures at 20% O2. G0 quiescence and granulocytic differentiation induced by low O2 concentrations is associated with cell cycle protein modifications: p27KIP1, pRb, CDK. This characterization allows FDCP-Mix usage as model to investigate fundamental balances responsible for hematopoietic long-term maintenance.

As the so-called “Mothership of the Human Genome,” the cell nucleus must keep all vital genetic information safe, but accessible, inside a strong protective envelope. The inner membrane of the nuclear envelope is lined by tough but adaptable proteins called lamins. While lamins polymerize into fibrous structures that hold up the “walls” of the nucleus, they also serve as an internal scaffold for the complex machinery involved in DNA replication and gene expression. It is in this later role that we have been looking for clues to premature and possibly to normal aging. One type of lamins, Lamin A is made through an unusual pathway involving a lipid dependent cleavage of a larger precursor called prelamin A. The functional significance of this processing pathway is that prelamin A cannot assemble and is inhibitory of proper lamina formation. Pathological cases of immature lamin A accumulation include Hutchinson-Gilford progeria syndrome (HGPS) or Progeria characterized by premature aging and Restrictive Dermopathy (RD), a lethal prenatal disease. We have previously shown that accumulation of prelamin A leads to cell cycle arrest and drastic changes in expression of genes involved in cell cycle control, among those, several members of the FoxO family of transcription factors. The goal of this study was to determine the mechanisms by which accumulation of uncleavable prelamin A activates FoxO-mediated cell cycle arrest. Cells expressing an uncleavable form of Lamin A in an inducible manner were used to determine subcellular distribution of FoxO3a upon accumulation of prelamin A. This was done by indirect immunofluorescence and Western blotting. The proliferation rate of these cells and controls expressing wild type Lamin A was also determined by measuring the incorporation of BrdU into DNA. During these experiments, it was hypothesized and observed that overexpression of prelamin A leads to redistribution of FoxO3a from the cytoplasm of the cell to the nucleoplasm. Expression of FoxO3a target genes was accordingly increased, leading to a decrease in cell proliferation. The information obtained from this study could not only be of interest in broadening our knowledge of the mechanisms of quiescence and aging in general, but also could inform the discussion of the use of several therapeutics for the treatment of Progeria and other diseases that result from the accumulation of prelamin A.

Κατά τη διάρκεια του κυτταρικού κύκλου ένας από τους σημαντικότερους μηχανισμούς ρύθμισης της ομοιόστασης των πρωτεϊνικών μορίων είναι η ελεγχόμενη στο χώρο και στο χρόνο αποδόμηση τους. Οποιαδήποτε ανωμαλία στη ρύθμιση των μηχανισμών αποδόμησης των πρωτεϊνών μπορεί να προκαλέσει σημαντική βλάβη στη λειτουργία του κυττάρου και να οδηγήσει σε κακοήθη εξαλλαγή του. Η αποδόμηση των κύκλινο-εξατώμενων αναστολέων του κυτταρικού κύκλου, p27 και p21, έχει δειχθεί να αυξάνει κατά την καρκινογένεση. Αν και η πρωτεόλυση των p27 και p21 έχει δειχθεί να μεσολαβείται από διαφορετικά μονοπάτια ωστόσο το περισσότερο γνωστό και καλύτερα τεκμηριωμένο είναι το μονοπάτι μέσω του συμπλόκου SCF (Skp2-cul1-Skp1) Ε3 λιγάσης της ουβικουιτίνης. Αρχικά οι πρωτεΐνες p27 και p21 φωσφορυλιώνονται από το σύμπλκο κυκλίνης Ε/Α-CDK2 στη θρεονίνη 187 (Thr187) και στη σερίνη 130 (Ser130) αντίστοιχα, και εν συνεχεία αναγνωρίζονται από το σύμπλοκο SCFSkp2, το οποίο διευκολύνει την πολύ-ουβικουιτινυλίωση και την αποδόμηση των πρωτεϊνών στο πρωτεόσωμα. Στη παρούσα εργασία μελετήθηκε η έκφραση των πρωτεϊνών: p27, p21, Skp2, cul1, pThr187-p27, κυκλίνη Α, κυκλίνη Ε και CDK2 σε 135 περιπτώσεις Β-λεμφωμάτων με Επιθετική [66 ΔΛΜΒΚ (35 λεμφαδενικά και 31 εξωλεμφαδενικά), 13 ΛΚΜ (8 κλασσικά και 5 βλαστικά) και 5 με ΛΛ βαθμού 3α/β)] και Ήπια βιολογική συμπεριφορά [9 ΛΛ (3 βαθμού 1, 6 βαθμού 2), 20 ΛΟΖ (12 λεμφαδενικά 6 εξωλεμφαδενικά, 2 σπληνικά) και 22 ΛΜΚ]. Η έκφραση της p27 παρατηρήθηκε μέγιστη στα ήπια λεμφώματα. Ωστόσο σε αρκετές περιπτώσεις επιθετικού λεμφώματος, κυρίως ΔΛΜΒΚ (~40%, >30%), η έκφραση της p27 βρέθηκε αυξημένη. Επιπλέον, σε όλες τις περιπτώσεις λεμφωμάτων εκτός του λεμφοζιδιακού και της οριακής ζώνης, παρουσιάστηκε αδυναμία αρνητικής συσχέτισης μεταξύ της p27 και της Skp2. Η μέγιστη έκφραση της p21, αντίθετα με την p27, παρατηρήθηκε στα ΔΛΜΒΚ, γεγονός που συνδέει την p21 με επιθετικότερη νόσο. Η πρωτεΐνη p21 δεν έδειξε να συσχετίζεται με τις πρωτεΐνες που είναι υπεύθυνες για την αποδόμηση της, γεγονός που πιθανόν να υποδεικνύει ότι στα Β-λεμφώματα που μελετήθηκαν η p21 δεν πρωτεολύεται από το σύμπλοκο SCFSkp2. Η υπερέκφραση της Skp2 στα ΔΛΜΒΚ, ΛΚΜ (κυρίως βλαστικά) και ΛΛ (βαθμού 3) καθώς και η ισχυρή θετική συσχέτιση με το δείκτη πολλαπλασιασμού, την κυκλίνη Α και τη CDK2 προσδίδουν στη πρωτεΐνη χαρακτηριστικά δείκτη επιθετικότητας. H cul1 έδειξε τα υψηλότερα επίπεδα έκφρασης και μία ισχυρή θετική συσχέτιση με την Skp2 στα ΔΛΜΒΚ, υποδεικνύοντας την παρουσία ενεργού SCF συμπλόκου, ωστόσο δεν παρατηρήθηκε παρόμοια συσχέτιση στους άλλους τύπους λεμφώματος. Υπερέκφραση της φωσφορυλιωμένης μορφής της p27 (pThr187-p27), δείχθηκε στα επιθετικότερα λεμφώματα. Επιπλέον, ισχυρή θετική συσχέτιση με το δείκτη πολλαπλασιασμού έδειξε η pThr187-p27, σε όλους τους τύπους λεμφώματος, δείχνοντας μία πιθανή σύνδεση της pThr187-p27 με την επιθετικότητα της νόσου. Συσχέτιση των παραπάνω πρωτεϊνών με τα κλινικά και εργαστηριακά ευρήματα των των ασθενών δείχνουν ότι στα επιθετικά λεμφώματα η υπερέκφραση των Skp2 και pThr187-p27 συνδέεται με βραχύτερο διάστημα ελεύθερο νόσο, ενώ η υπερέκφραση της pThr187-p27 έδειξε να συνδέεται και με πτωχότερη ολική επιβίωση. Επίσης κατά την πολυπαραγοντική ανάλυση, δείχθηκε για πρώτη φορά ότι η έκφραση της pThr187-p27 αποτελεί ανεξάρτητο προγνωστικό παράγοντα για τη συνολική επιβίωση όχι μόνο ανάμεσα στις υπό μελέτη πρωτεΐνες αλλά και σε συνάρτηση με τις κλινικές παραμέτρους στα επιθετικά Β-λεμφώματα / Cell cycle is tightly regulated by a functionally conserved group of proteins which together constitute the basic cell division machinery that controls cell cycle progression. Altered expression of these proteins are almost always detected in human cancer cells. However, aberrant expression of these proteins can be the cause of malignant transformation but also in some cases, can be the consequence of cancer progression. The cell cycle regulators p27 and p21 play a central role in the suppression of tumorigenesis in a variety of human cancers. Of particular importance for the development of human cancers is the ubiquitin dependent degradation of p27 and p21 by the proteasome. This pathway is controlled by many complexes, however the most well studied is the SCFSkp2 complex. p27 and p21 proteins are phosphorylated at a conserved Threonine (T187) and Serine (Ser130) residue by cyclin E/A-cdk2 complexes, respectively, and the Skp2 protein facilitates the polyubiquitylation of p27 and p21 by the SCF complex. In the present study was examined the immunoexpression of p27, p21, Skp2, cul1, pThr187-p27, cyclin Α, cyclin Ε and CDK2 in 135 cases with B-cell Lymphoma with aggressive [66 DLBCL (35 nodal and 31 extranodal), 13 MCL (8 classical and 5 blastic) and 5 FL grade 3α/β)] and indolent biological behaviour [9 FL (3 G1, 6 G2), 20 MZL (12 nodal, 6 extranodal, 2 splenic) and 22 SLL]. P27 was overexpressed in indolent B-cell lymphomas. However, many cases with aggressive B-cell lymphoma, mainly DLBCLs (~40%, >30%),, showed increased expression of p27. In addition, all lymphoma cases except the FLs and MZLs failed to show an inverse correlation between p27 and Skp2. The highest expression of p21 was observed in DLBCL, indicating that p21 expression is associated with more aggressive neoplasias. The levels of p21 expression did not correlate with Skp2 and cul1, indicating that SCFSkp2 complex might not be capable for p21 degradation in B-cell lymphomas. Overexpression of Skp2 in DLBCLs, MCLs (mainly blastic type) and FL (Grade 3), as well as the strong positive correlation with cyclin A and CDK2, indicate that Skp2 may be a putative biomarker of tumor aggressiveness. The expression of cul1 was higher in DLBCLs, and correlate well with the expression of Skp2, indicating the presence of active SCFSkp2 complex. However, a similar correlation was not observed in other lymphoma groups. The phosphorylated form of p27 (pThr187-p27) was overexpressed in aggressive cases. Furthermore, a strong positive correlation between pThr187-p27 and the proliferation index, was observed in all lymphoma cases. This correlation may indicate that pThr187-p27 could be used as a marker of tumor aggressiveness. The correlation of the studied proteins with the clinical and laboratory data showed that in the aggressive lymphomas the expression of Skp2 and pThr187-p27 is associated with poor disease free survival rate, and pThr187-p27 is also associated with shorter overall survival. In the present study, the multivariant cox analysis showed that the expression of pThr187-p27 is an independent prosgnostic factor for the overall survival among other clinical parameters.

Made available in DSpace on 2014-06-11T19:23:45Z (GMT). No. of bitstreams: 0 Previous issue date: 2007-06-01Bitstream added on 2014-06-13T19:30:16Z : No. of bitstreams: 1 mazon_rc_me_arafcf.pdf: 520188 bytes, checksum: 4af452f70d4ec4f1806399a4a3c1661c (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Universidade Estadual Paulista (UNESP) / O mdm2 parece controlar o tráfego da proteína p53 do núcleo-citoplasma enquanto a proteína p27 é um inibidor de CDK que controla a fase G1 para S do ciclo celular. Em contraste, a catepsina B parece induzir um sinal de apoptose independente de caspase na presença do HPV. Entretanto, a influência da infecção pelo HPV na carcinogênese oral e o envolvimento na desregulação das proteínas do ciclo celular não são claras. Assim, o objetivo deste estudo foi avaliar a associação entre a expressão de proteínas do ciclo celular, p27, mdm2 e catepsina B e câncer oral na presença do HPV. Cinqüenta e cinco biópsias orais representando lesões benignas (LB), lesões potencialmente malignas (LPM) e lesões malignas (LM). A detecção e tipagem do HPV (6/11,16,18, 31 e 33) foi realizada pela reação da polimerase em cadeia (PCR). A expressão quantitativa de p27, mdm2 e catepsina B foi analisada pela reação imunohistoquímica. Vinte e uma (38%) de 55 lesões orais foram positivas para HPV. O DNA do HPV 6/11 foi encontrado em 6 (33%), HPV 16 em 1(5%) e o HPV 18 em 14 (72%). Não foi encontrado HPV 31 e 33. De 55 biópsias, foi encontrada alta expressão de todas as proteínas: o p27 foi encontrado em 37 (67,2%) lesões, mdm2 em 17 (30,9%) e a catepsina B em 37 (67,2%). Entre lesões orais de HPV positivo, uma superexpressão de p27, mdm2 e catepsina B foi encontrada, respectivamente, em 6 (33%) de 18 lesões benignas, 4 (22%) de 18 lesões potencialmente malignas e 11 (57,9%) de 19 lesões malignas. Adicionalmente, o HPV16/18 (11/58%) foi detectado em lesões malignas com alta expressão de todas as proteínas. Nós concluímos que os tipos de HPVs de alto risco devem estar associados com carcinoma oral, bem como, com a superexpressão de p27, mdm2 e catepsina B. Estes resultados sugerem que os tipos de HPVs de alto risco podem desregular o controle do ciclo celular, contribuindo para a carcinogênese oral. / Mdm2 seems to control p53 nucleus-cytoplasm traffic while p27 is a CDK inhibitor which control G1 to S phase of the cell-cycle. In contrast, cathepsin B is reported in HPVinduced apoptotic signalling caspase-independent. However, the influence of HPV infection in oral carcinogenesis and its involvement to this cell-cycle proteins dysfunction remain still unclear. The purpose of this study was to clarify the association between the expression of cell-cycle proteins, p27, mdm2 and cathepsin B and oral cancer HPV-related. Fifty-five oral biopsies presenting benign oral lesions (BL), potentially malignant lesions (PML) and malignant oral lesions (ML). HPV detection and typing (6/11, 16, 18, 31 and 33) was performed using polymerase chain reaction. p27, mdm2 and cathepsin B quantitative expression were performed by immunohistochemistry. Twenty one (38%) of the 55 oral lesions were positive for HPV, of which HPV6/11 DNA was found in 6 (33%), HPV 16 in 1(5%) e o HPV 18 in 14 (72%). No HPV positivity was found to HPV31 and 33. Of the 55 biopsies, a high expression of all proteins was found: to p27 in 37 (67,2%), mdm2 was observed in 17 (30,9%) slides, and cathepsin B in 37 (67,2%). Among HPV-positive oral lesions, an overexpression for mdm2, p27 and cathepsin B was found, respectively, in 6 (33%) out of 18 BL, 4 (22%) out of 18 PML and 11 (57,9%) out of 19 ML. In addition, HPV16/18 (11/58%) was detected in OSSC with high expression of all proteins. We conclude that high-risk HPV types might be associated with oral carcinoma, as well as, with the overexpression of mdm2, p27 and cathepsin B. These results suggest that high-risk HPV types might deregulate cell-cycle control, contribuiting to oral carcinogenesis.

Le cycle cellulaire est un processus finement régulé à différents niveaux. p27 est un inhibiteur des complexes cyclines/CDK et cette fonction lui confère un rôle antiprolifératif lorsqu'il est localisé dans le noyau. De nombreuses études ont montré que p27 se comporte comme un suppresseur de tumeur lorsqu'il est localisé dans le noyau des cellules via l'inhibition des cyclines/CDK. De manière surprenante, p27 a également des fonctions oncogéniques dans certaines situations, notamment lorsqu'il est présent dans le cytoplasme. Il s'avère qu'en plus de ses fonctions de régulateur du cycle cellulaire, p27 est également impliqué dans la régulation d'autres processus cellulaires, comme la migration, la cytocinèse, la transcription ou encore l'autophagie et la différenciation. Durant ma thèse, j'ai caractérisé deux de ces nouvelles fonctions en mettant en lumière un rôle de p27 dans la régula.on des invadopodes ainsi que dans l'oncogenèse pancréatique.Mon premier objectif a été de comprendre la fonction de l'interaction de p27 avec la protéine Cortactine, un nouveau partenaire de p27.Cette protéine joue un rôle important dans la régulation de l'invasion cellulaire. J'ai confirmé cette interaction dans différents types cellulaires et observé une colocalisation au niveau des invadopodes. J'ai également cartographié leurs domaines d'interaction respectifs et montré que l'interaction de p27 avec Cortactine était induite par une stimulation avec du sérum. L'interaction p27/Cortactine permet le recrutement de PAK1, une sérine/thréonine kinase impliqué dans l'invasion cellulaire et favorisant notamment le renouvellement des invadopodes, sur Cortactine. J'ai également observé que les cellules invalidées pour p27 présentent de nombreux invadopodes et dégradent la matrice extracellulaire de manière très importante par rapport aux cellules exprimant p27. Par des approches d'inhibiteurs et de siARN j'ai mis en évidence que ce phénotype implique la voie Rac1/PAK1/phospho-Ser113-Cortactine qui est sous-activée en l'absence de p27 à cause du défaut de recrutement de PAK1 sur Cortactine, stabilisant ainsi les invadopodes. Mon second objectif a été d'étudier les mécanismes par lesquels p27 régule l'oncogenèse pancréatique. En effet, différentes études cliniques ou chez la souris ont montré que la localisation nucléaire de p27 était requise pour son rôle de suppresseur de tumeur dans le pancréas. Or nous avons constaté dans un modèle murin génétique d'oncogenèse pancréatique induite par l'activation de K-Ras que p27 était exclu du noyau avant l'apparition des premières lésions, suggérant un rôle précoce dans l'oncogenèse de ce tissu. De manière surprenante, l'étude comparative par immunomarquage de pancréas de souris p27+/+, p27-/- et p27CK-/CK-, un modèle de souris knock-in où p27 n'est plus capable d'inhiber les cyclines/CDK, n'a pas montré d'effet de p27 sur la prolifération dans le pancréas exocrine. Par contre, ces études ont montré une localisation anormale de plusieurs marqueurs de polarité acinaire ainsi qu'une réexpression des facteurs de transcription Sox9 et Pdx1, impliqués dans le processus de transdifférenciation cellulaire à l'origine de l'oncogenèse pancréatique appelée métaplasie acino-canalaire. Nous avons montré que p27 régulait de manière directe la transcription de Sox9 en interagissant avec son promoteur, suggérant que p27 participe normalement à la répression transcriptionnelle de Sox9 dans le noyau, réprimant ainsi la métaplasie acino-canalaire.Ainsi, mes travaux de thèse ont permis l'identification de deux nouvelles fonctions de p27. Une fonction oncogénique, indépendante de son activité d'inhibiteur des CDK/cyclines, par laquelle p27 régule la protéine Cortactine, et par ce biais les invadopodes et l'invasion ainsi qu'une fonction de suppresseur de tumeur dépendante des cyclines/CDK via la répression de la transcription de Sox9 dans les cellules acinaires du pancréas. / Cell cycle is a tightly regulated process. One level of regulation is provided by p27, a cyclin/ CDK inhibitor and as such, p27 has an antiproliferative function. Several studies have shown that p27 is a tumor suppressor when it is located in the nucleus via the inhibition of cyclins/ CDKs. Surprisingly, p27 may also play oncogenic roles depending on the cellular context, especially when it is excluded from the nucleus. In fact, several lines of evidence indicate that p27 functions extend beyond cell cycle regulation and that p27 also regulates cell migration, cytokinesis, transcription, autophagy and stemness/differenciation. During my PhD, I have characterized two novel p27 functions, one in the regulation of invadopodia, and the second in pancreatic oncogenesis.My first aim was to investigate the function of the interaction between p27 and Cortactin, a new p27-interacting protein which is an important regulator of cell invasion. I confirmed this interaction in different cell lines and found that p27 and Cortactin colocalized in invadopodia. I have mapped the domains mediating the interaction in both proteins and found that this interaction is induced after serum stimulation. p27 allows the recruitment of PAK1, a serine/ threonine kinase involved in cell invasion which promotes invadopodia turnover, on Cortactin. I also found that p27 knock-out cells have an increased number of invadopodia and degrade extracellular matrix more efficiently than wild-type cells. Using inhibitors and siRNAs I have shown that this phenotype involves the Rac1/PAK1/phospho-Ser113-Cortac.n pathway, which is underactivated in absence of p27 due to the PAK1/Cortactin interaction defect, causing a stabilization of invadopodia.My second aim was to study the mechanism by which p27 regulates pancreatic oncogenesis. Severals studies in the clinic or in animal models have shown that nuclear localization of p27 is required for its tumor suppressor function in the pancreas. In a genetic mouse model of K- Ras driven pancreatic oncogenesis, I found that p27 was excluded from the nucleus before the apparition of lesions, suggesting an early function in oncogenesis in this tissue. Surprisingly, comparative studies of pancreas from p27+/+, p27-/- and p27CK-/CK- (a knock- in mouse model where p27 no longer binds cyclins/CDKs) mice by immunostaining did not show any difference in proliferation in the exocrine pancreas. However, these studies have shown the mislocalization of different acinar polarity markers and the re-expression of two transcription factors, Sox9 and Pdx1, which are involved in acinar-to-ductal metaplasia, a cell transdifferenciation process thought to be the underlying cause of pancreatic oncogenesis. I have found that p27 regulates Sox9 transcription and directly interacts with its promoter, suggesting that p27 participates in the transcriptionnal repression of Sox9 in normal conditions to prevent acinar-to-ductal metaplasia. Overall, my PhD work has allowed the identification of two novel roles of p27. An oncogenic function, independent of its cyclin/CDK inhibitory activity, by which p27 regulates Cortac.n, invadopodia and cell invasion and a tumor suppressor function dependent of cyclin/CDK via the repression of Sox9 transcription in pancreas acinar cells.

The emergence of tamoxifen or aromatase inhibitor resistance is a major problem in the treatment of breast cancer. The molecular signaling mechanism of antiestrogen resistance is not clear. Understanding the mechanisms by which resistance to these agents arise could have major clinical implications for preventing or circumventing it. Therefore, in this dissertation we have investigated the molecular mechanisms underlying antiestrogen resistance by studying the contributions of reactive oxygen species (ROS)-induced redox signaling pathways in antiestrogen resistant breast cancer cells. Our hypothesis is that the conversion of breast tumors to a tamoxifen-resistant phenotype is associated with a progressive shift towards a pro-oxidant environment of cells as a result of oxidative stress. The hypothesis of this dissertation was tested in an in vitro 2-D cell culture model employing state of the art biochemical and molecular techniques, including gene overexpression, immunoprecipitation, Western blotting, confocal imaging, ChIP, Real-Time RT-PCR, and anchorage-independent cell growth assays. We observed that tamoxifen (TAM) acts like both an oxidant and an antioxidant. Exposure of tamoxifen resistant LCC2 cell to TAM or 17 beta-estradiol (E2) induced the formation of reactive oxidant species (ROS). The formation of E2-induced ROS was inhibited by co-treatment with TAM, similar to cells pretreated with antioxidants. In LCC2 cells, treatments with either E2 or TAM were capable of inducing cell proliferation which was then inhibited by biological and chemical antioxidants. Exposure of LCC2 cells to tamoxifen resulted in a decrease in p27 expression. The LCC2 cells exposed to TAM showed an increase in p27 phosphorylation on T157 and T187. Conversely, antioxidant treatment showed an increase in p27 expression and a decrease in p27 phosphorylation on T157 and T187 in TAM exposed cells which were similar to the effects of Fulvestrant. In line with previous studies, we showed an increase in the binding of cyclin E–Cdk2 and in the level of p27 in TAM exposed cells that overexpressed biological antioxidants. Together these findings highly suggest that lowering the oxidant state of antiestrogen resistant LCC2 cells, increases LCC2 susceptibility to tamoxifen via the cyclin dependent kinase inhibitor p27.

Indiana University-Purdue University Indianapolis (IUPUI) / Cyclin Dependent Kinase regulation is often manipulated by cancer cells to promote unlimited proliferation. P27 is an important regulator of Cyclin E/CDK 2, which has been found in low amounts in many types of malignant cancers. Lovastatin has been shown to cause cell cycle arrest in the G1 phase of the cell cycle by increasing the P27 protein. There has been some question, however, if lovastatin regulates P27 at the transcriptional or translational level. Although it has been claimed that P27 expression regulation is due to an IRES located in its 5’UTR, other studies suggested that P27 expression is regulated at the level of transcription. To further investigate the regulation mechanism of P27 expression, the 5’-UTR of P27 and its deletion mutants were examined using a luciferase reporter gene in HeLa cells following exposure to lovastatin. It was found that lovastatin stimulated a significant 1.4 fold increase in its promoter activity of the full length 5’UTR (575). Deletion of 35 nucleotides from the 5’ end of the UTR eliminated the lovastatin-induced increase in promoter activity. Further mapping analyses of the first 35 bases showed that two regions, M1 (575-559) and M3 (543-527), were less sensitive to lovastatin than the other mutated constructs. Since M1 and M3 still showed some activity, a construct was created with deletions in both the M1 and M3 regions. This showed no increase in luciferase activity when exposed to lovastatin. Looking at RNA levels, there was a 1.5 fold increase in RNA when the full length 5’UTR was inserted into HeLa cells and exposed to 81 µM of lovastatin. In contrast, there was no increase in RNA when M1/M3 (575-559; 543-527) was inserted into HeLa cells and exposed to 81 µM of lovastatin. In addition, there was a 1.6 fold increase in endogenous P27 RNA levels after HeLa cells were exposed to 81 µM of lovastatin. In all of these experiments, there seems to be two promoters that work cooperatively: M1 (575-559) and M3 (543-527).