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One of the most challenging questions in the study of cancer is the origin and the nature of the cells that initiate cancer. Accumulated studies have provided many molecular origins of cancers but we still do not know what kind of cells in the tissues transform to cancer cells. Therefore, identifying the cellular origin of these cells is critical for the development of better prognosis, diagnosis and treatment of cancer. A stem cell origin of cancer has been postulated over 150 years. Recent cancer stem cell studies have opened a new window on aspects of the cellular origin of cancer. In this communication, we will address two possible cellular origins of cancer in epithelial tumor development using mouse skin cancer model: tissue specific stem cells, and cells from other organs. To demonstrate contribution of the tissue specific stem cells in tumor development, we monitored the contribution of keratin-15 positive hair follicle bulge stem cells to skin tumor development in the multistage skin carcinogenesis model with Krtl- 15CrePRl;R26R transgenic mice. We found that labeled progeny of the keratin-15 positive bulge stem cells migrate into papillomas and these cells contribute to almost all papilloma samples by 20 weeks of promotion. Additionally, in contrast to the transient contribution of bulge-derived cells in skin wound healing, consistent percentage of the bulge-derived cells stay in the papillomas over 20 weeks. Furthermore, papillomas have heterogeneous expression of the codon 61 signature Ha-ras mutation, with approximately 30 percent of bulge-derived regions expressing the mutation. To determine the contribution of exogenous sources in skin tumor development, we examined bone marrow-derived cells (BMDCs) in the skin tumors from the allogeneic gender-mismatched bone marrow transplantation recipient mice after chemical skin carcinogenesis. We observed that genetically marked (EGFP) BMDCs were detected in the epithelial part of skin wounds and also skin tumors, and we found greater degree of BMDC contribution in chronic ulcer-related skin lesions. Lastly, an in-vitro assay demonstrated plasticity of BMDCs by inducing keratin-14 expressing cells from mesenchymal stem cells. These results demonstrated that hair follicle bulge stem cells and also BMDCs are able to contribute to skin tumor development.

Les infections génitales par les virus du papillome humains (HPV) sont les infections virales sexuellement transmises, les plus communes chez les femmes en âge de procréer. Il est désormais bien établi que l’infection persistante par les HPV classés «à haut risque» est l’un des facteurs indispensables au développement de lésions précancéreuses et cancéreuses du col de l’utérus. Ces HPV semblent aussi être impliqués dans le développement d’autres cancers de la région ano-génitale et pourraient être également impliqués dans les cancers de la tête et du cou. Durant cette dernière décennie, des études croissantes tendent à établir un rôle étiologique des HPV dans les dysfonctionnements gestationnels. La détection des ADN HPV dans les placentas issus d’avortements spontanés et leur capacité exceptionnelle à se répliquer in vitro dans les cellules trophoblastiques cultivées en monocouche, ont apporté de nouvelles perspectives quant à la possibilité que le placenta pourrait constituer aussi un tropisme naturel des infections par HPV.<p>Six jours après la fécondation et suite à l’accolement du blastocyste à l’épithélium utérin, le trophoblaste s’engage dans des processus actifs de prolifération, d’invasion et de différenciation complexe pour la construction de l’interface physiologique indispensable aux échanges essentiels entre la mère et l’enfant ;le placenta. De façon intéressante, ses propriétés sont similaires à celles de la cellule tumorale maligne. Néanmoins, ses mécanismes sont étroitement régulés dans le trophoblaste, à la fois dans l’espace et le temps, assurant un développement normal à chaque étape de la grossesse.<p>Devant toutes ces données, nous avions émis l’hypothèse que l’expression des protéines précoces E5, E6 et E7 d’HPV de type 16 (de haut risque), pourraient modifier le développement des trophoblastes infectés. Les résultats obtenus durant ce travail de doctorat démontrent que la protéine virale E5, hautement hydrophobe, est cytotoxique et affecte la viabilité du trophoblaste. Cette cytotoxicité est neutralisée, et la viabilité est améliorée, lorsque les oncoprotéines majeures E6 et E7 sont exprimées en présence de la protéine E5. Lorsque toutes les protéines précoces sont exprimées sous le contrôle de leur propre promoteur (LCR), la viabilité est favorisée. Ces observations ont été confirmées dans les cellules cervicales également. Il a été précédemment rapporté que les oncoprotéines E6 et E7 affectaient l’adhésion du trophoblaste aux cellules endométriales. Dans le présent travail, il a été retrouvé que la protéine E5 diminuait elle aussi l’adhésion, non seulement aux cellules endométriales, mais aussi au support de culture cellulaire. Les capacités de migration et d’invasion de la matrice extracellulaire sont augmentées par l’expression de E5 et dans une plus large proportion par l’expression de E6 et E7. Des résultats similaires ont été obtenus lorsque toutes les protéines de la région précoces sont exprimées sous le contrôle de leur propre promoteur (LCR). La diminution de l’expression de la E-cadhérine est considérée comme un marqueur de malignité et de mauvais pronostic pour les cancers. Nous avons démontré que l’expression de E5, E6 ou de E7, inhibait l’expression de la E-cadhérine, reflétant l’impact des oncoprotéines du virus HPV-16 sur la diminution de l’adhésion et l’augmentation du pouvoir invasif des cellules trophoblastiques. L’investigation d’autres marqueurs de malignité et de tolérance immunitaire, l’étude de l’impact du virus HPV-6 (de bas risque) sur la migration et l’invasion des cellules trophoblastiques, et l’étude de la capacité des protéines précoces d’HPV-16 à influencer l’entrée des particules virales, ont fait l’objet de résultats préliminaires, ouvrant de larges perspectives.<p><p><p>Genital Human Papillomavirus (HPV) infections are the most common sexually transmitted infections amongst women on the age of reproduction. It is well established that persistent infection with high-risk HPVs is the necessary factor in the causation of precancerous and cancerous cervical lesions. High-risk HPVs have also been reported to be involved in the causation of head and neck cancers and other anogenital cancers. On this last decade, growing data are attempting to study the potential etiological association of HPV with gestational dysfunctions. The detection of HPV DNA in placentas resulting from spontaneous abortions and the unique ability of multiple HPV types to replicate in vitro in trophoblastic cells cultured in a monolayer system, rise new questions over the HPV tropism. <p>Six days following fertilization and once the apposition of the blastocyst on the uterine wall takes place, the trophoblast, in a very active and complex process, starts to proliferate, invade and to differentiate in order to build a physiological interface; the placenta, from where multiple mother/foetus exchanges occur. Interestingly, the way that the trophoblast behaves is very similar to malignant tumoural cells. However, the trophoblast obeys to strict spatial-temporal regulatory confines, insuring a proper development all along the pregnancy.<p>In regard to these data, we hypothesised that the expression of the high-risk HPV type 16 oncoproteins E5, E6 and E7, might modify the development of the infected trophoblast. During my Ph.D study, I demonstrated that the highly hydrophobic protein E5 is localized in many interne membranes compartments of the transfected trophoblast. E5 affects the viability of transiently and stably transfected trophoblastic cells. E6 and E7, favouring cell growth, neutralised the E5 cytotoxic effect. All HPV-16 early proteins, when expressed under the control of their endogenous promoter (LCR), favoured trophoblastic growth. These observations were also observed in cervical cell lines. In addition, E5 decreased the adhesiveness of trophoblastic cells to the tissue culture plastic and to endometrial cells similarly as previously described for E6 and E7. Cells expressing E6, E7 and in less extend E5 favoured chemotaxic migration and matrigel invasion compared to the cells expressing the LacZ control. These effects were also observed when early proteins were expressed under the control of their own viral promoter (LCR). Interestingly, the E-cadherin was down regulated in trophoblastic cells expressing E5, E6 and E7. In conclusion, HPV-16 early proteins enhanced trophoblastic growth and intensify the malignant phenotype by impairing cell adhesion leading to increased cellular motile and invasive properties. HPV-16 E5 participated, with E6 and E7, in these changes by impairing E-cadherin expression, a hallmark of malignant progression. Additional preliminary results consisting on the investigation of other markers of malignancy and immune tolerance, on studying the impact of the low-risk HPV type 6 early proteins on the migratory and invasive properties of trophoblastic cells and on the study of the ability of HPV-16 to influence the entry of virus particules, allowed to open wide perspectives.<p><p><p> / Doctorat en Sciences / info:eu-repo/semantics/nonPublished

published_or_final_version / Pathology / Master / Master of Philosophy

The studies described in this thesis investigated the relationship between DNA repair mechanisms, aflatoxin B1 (AFB1)-induced DNA damage and carcinogenesis. Mice deficient in 8-oxoguanine glycosylase (OGG1, the rate-limiting enzyme in repair of oxidized guanine), mice heterozygous for OGG1, and wild type mice, were exposed to a single tumourigenic dose (50 mg/kg) of AFB1. Neither ogg1 genotype nor AFB1 treatment affected levels of oxidized guanine in lung or liver 2 h post-treatment. ogg1 (-/-) mice had increased susceptibility to AFB1 toxicity, as reflected by increased mortality within one week of AFB1 exposure. AFB1 treatment did not significantly increase lung or liver tumourigenesis compared to DMSO controls. No difference was observed between ogg1 genotypes, although a non-significant trend towards AFB1-treated ogg1 (-/-) mice being more susceptible to tumourigenicity was apparent. Overall, deletion of ogg1 did not significantly affect AFB1-induced DNA damage or tumourigenicity, suggesting that oxidized guanine may not be a major contributor to AFB1-induced tumourigenesis. The effects of AFB1 on DNA repair were assessed in p53 (a protein implicated in regulation of DNA repair) wild type and heterozygous mice. p53 (+/+) mice treated with 0, 0.2 or 1.0 ppm AFB1 for 26 weeks had increased nucleotide excision repair (NER) activities in lung and liver compared to control, which may represent an adaptive response to AFB1-derived DNA adducts. In p53 (+/-) mice, the AFB1-induced increase in NER was significantly attenuated, suggesting that loss of one allele of p53 limits the ability of NER to up-regulate in response to AFB1-induced DNA damage. Twenty-six week exposure to AFB1 did not affect base excision repair (BER) in p53 (+/+) mouse lung or liver compared to control. BER was significantly decreased in livers from mice exposed to 1.0 ppm AFB1 compared to those exposed to 0.2 ppm AFB1, a result that was not due to liver cell death or to altered levels of OGG1 protein. In lungs and livers of p53 (+/-) mice, BER activity was unchanged by AFB1. As such, the difference in BER response between 0.2 ppm and 1.0 ppm AFB1 treatment seen in the p53 (+/+) mice appears to be p53 dependent. / Thesis (Ph.D, Pharmacology & Toxicology) -- Queen's University, 2013-10-17 22:24:31.577

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.

IL-33 participa em diversas doenças com funções pró-inflamatórias e protetoras, de acordo com o contexto do microambiente. Com relação a biologia tumoral, o papel de IL-33 ainda é controverso. Estudos demonstraram que IL-33 possui efeitos pró e anti-inflamatórios em diferentes modelos animais de câncer. A presença desta citocina no estroma favorece a imunossupressão pela ativação de células T reguladoras e células mieloides supressoras. IL- 33 pode em outras situações promover a imunogenicidade e a resposta imune antitumoral de tipo 1 através das células T citotóxicas e células Natural Killers. Contudo o efeito preciso de IL-33 em diferentes tipos de câncer permanece incerto. Sendo assim, compreender o papel de IL-33 na imunobiologia do câncer, poderia direcionar esta citocina como um possível alvo em imunoterapias contra o câncer. Considerando, portanto, a pluralidade desta citocina no desenvolvimento de uma resposta imune, no presente estudo buscamos avaliar os efeitos do tratamento com anti-IL-33 em modelo experimental de carcinoma espinocelular de pele em camundongos BALB/c de linhagem selvagem. Ao final dos protocolos de indução e tratamento, a análise histopatológica revelou que o tratamento com anti-IL-33 levou a menor incidência de carcinoma espinocelular in situ e diminuição das atipias celulares e, consequentemente, do grau de displasia. O tratamento com anti-IL-33 levou a aumento nos percentuais de células B e diminuição nas percentagens de linfócitos T CD4+, células dendríticas, células TREG e macrófagos isolados do microambiente tumoral. Ademais, o tratamento com anti-IL-33 levou a aumento na percentagem de linfócitos T CD4+ produtores de IFN- e menor percentagem de linfócitos T CD4+ e CD8+ produtores de IL-4 nos linfonodos. Em camundongos submetidos ao tratamento, observou-se menor produção de TGF- no microambiente tumoral, sem interferir de modo significativo com a produção de IFN-, IL-4, IL-10 e IL-17. Os nossos resultados indicam que o tratamento com anti-IL-33 poderia ser alvo de novos estudos em busca de estratégias terapêuticas para o carcinoma espinocelular de pele. / IL-33 participates in several diseases with pro-inflammatory and protective functions, according to the context of the microenvironment. Related to tumor biology, the role of IL-33 is still controversial. Studies have shown that IL-33 has pro and anti-inflammatory effects in different animal models of cancer. Its presence in the stromal and tumor serum increases the immunosuppression by the activation of regulatory T cells and myeloid-derived suppressor cells. On the other hand, the intracellular form in tumor cells promotes immunogenicity and the antitumor type 1 immune response through cytotoxic T cells and natural killer cells. However, the precise effect of IL-33 on cancer conditions remains uncertain. Thus, understanding its role in the immunobiology of cancer could target this cytokine as a marker in cancer immunotherapies. Considering, the range of IL-33 in the development of an immune response, this study aims to evaluate the effects of the anti-IL-33 treatment on wild type BALB/c mouse squamous cell carcinoma (SSCC) development. Histopathological analysis revealed that anti-IL-33 treatment decreased the dysplasia. In addition, anti-IL-33 treatment showed an increasing percentage of B cells and reduced the percentage of CD4+ T lymphocytes, dendritic cells, TREG cells and macrophages in the tumor microenvironment. In the lymph node, anti-IL-33 treatment induced a shift towards the TH1 type cytokine profile and reduced the percentage of IL-4 expressing CD4+ and CD8+ cells. Additionally, anti-IL-33 treatment showed a reduced TGF- production in the tumor microenvironment, but with no changes to the IFN-, IL-4, IL-10 e IL-17 production. Taken together these results indicate that anti-IL-33 treatment could be the subject of further studies of therapeutic strategies for squamous cell carcinoma of the skin.