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Lung cancer is a leading cause of cancer-related mortality irrespective of gender. The Sulfiredoxin (Srx) and Peroxiredoxin (Prx) are a group of thiol-based antioxidant proteins that plays an essential role in non-small cell lung cancer. Understanding the molecular characteristics of the Srx-Prx interaction may help design the strategies for future development of therapeutic tools. Based on existing literature and preliminary data from our lab, we hypothesized that the Srx plays a critical role in lung carcinogenesis and targeting the Srx-Prx axis or Srx alone may facilitate future development of targeted therapeutics for prevention and treatment of lung cancer. First, we demonstrated the oncogenic role of Srx in urethane-induced lung carcinogenesis in genetically modified FVB mice. The Srx-null mice showed resistance to urethane-induced lung cancer. Second, we demonstrated the Srx and Prx sites important for Srx-Prx interaction. The orientation of this arm is demonstrated to cause some steric hindrance for the Srx-Prx interaction as it substantially reduces the rate of association between Srx and Prx. Finally, we carried out virtual screening to identify molecules that can successfully target Srx-Prx interaction. Multiple in-silico filters were used to minimize the number of chemicals to be tested. We identified ISO1 as an inhibitor of the Srx-Prx interaction. KD value for Srx-ISO1 interaction is calculated to be 42 nM. Together, these data helps to identify an inhibitor (ISO1) of the Srx-Prx interaction that can be further pursued to be developed as a chemotherapeutic tool.

Bone morphogenetic protein (BMP) signalling plays key roles in skin development and also possesses a potent anti-tumour activity in postnatal skin. To study mechanisms of the tumour-suppressive role of BMPs in the skin, a transgenic (TG) mouse model was utilized, in which a transgenic expression of the BMP antagonist Noggin was targeted to the epidermis and hair follicles (HFs) via Keratin 14 promoter. K14-Noggin mice developed spontaneous HF-derived tumours, which resembled human trichofolliculoma. Initiation of the tumours was associated with a marked increase in cell proliferation and an expansion of the hair follicle stem/early progenitor cells. In addition, the TG mice showed hyperplastic changes in the sebaceous glands and the interfollicular epidermis. The epidermal hyperplasia was associated with an increase in the susceptibility to chemically-induced carcinogenesis and earlier malignant transformation of chemically-induced papillomas. Global gene expression profiling revealed that development of the trichofolliculomas was associated with an increase in the expression of the components of several pro-oncogenic signalling pathways (Wnt, Shh, PDGF, Ras, etc.). Specifically, expression of the Wnt ligands and (β-catenin/Lef1) markedly increased at the initiation stage of tumour formation. In contrast, expression of components of the Shh pathway was markedly increased in the fully developed tumours, compared to the tumour placodes. Pharmacological treatment of the TG mice with the Wnt and Shh antagonists resulted in the stage-dependent inhibition of the tumour initiation and progression, respectively. Further studies revealed that BMP signalling antagonizes the activity of the Wnt and Shh pathways via distinct mechanisms, which include direct regulation of the expression of the tumour suppressor Wnt inhibitory factor 1 (Wif1) and indirect effects on the Shh expression. Thus, tumour suppressor activity of the BMPs in skin epithelium depends on the local concentrations of Noggin and is mediated, at least in part, via stage-dependent antagonizing of the Wnt and Shh signalling pathways.

Problématique: Le virus du papillome humain (VPH) est présent dans près de 50% des cancers de l’oropharynx. Le potentiel oncogénique du VPH est encodé dans les oncoprotéines E6 et E7, qui agissent en modulant différents gènes, dont les gènes suppresseurs de tumeur p53 et pRb. Les cellules VPH positives démontrent une altération au niveau de la signalisation de la réponse aux dommages à l’ADN (RDA), un mécanisme de contrôle dans l’arrêt de la croissance des cellules ayant subit des dommages au niveau de leur ADN. Hypothèse et objectifs : Nous croyons que les défauts au niveau de la RDA des cancers VPH positifs peuvent être exploités afin de sensibiliser préférentiellement les cellules cancéreuses aux traitements de radiothérapie. Cette stratégie de recherche nécessite l’élaboration d’un modèle cellulaire de carcinogenèse isogénique pour le cancer de l’oropharynx que nous proposons de développer et de caractériser. L’étude vise à dériver des lignées isogéniques à partir de kératinocytes primaires et cellules épithéliales de l’oropharynx pour ensuite valider la carcinogenèse de notre modèle in vitro & in vivo Méthodologie : Des lignées cellulaires de kératinocytes primaires et de cellules épithéliales de l’oropharynx ont été successivement modifiées par transduction afin de présenter les mutations associées aux cancers de l’oropharynx induits par le VPH. Les cellules ont été modifiées avec des lentivirus codants pour la télomérase (hTERT), les oncogènes E6, E7 et RasV12. Afin de valider la cancérogenèse in vitro de notre modèle, des études d’invasion en matrigel et de croissance sans ancrage en agar mou ont été réalisées. Les populations cellulaires transformées ont été ensuite introduites dans des souris immunodéficientes afin d’évaluer leur tumorogénicité in vivo. Résultats : À partir des plasmides recombinés construits par méthodes de clonage traditionnelle et de recombinaison « Gateway », nous avons produit des lentivirus codants pour la télomérase humaine (hTERT), les oncogènes viraux E6 et E7 et l’oncogène Ras. Les kératinocytes primaires et cellules épithéliales de l’oropharynx ont été infectés successivement par transduction et sélectionnés. Nous avons validé l’expression de nos transgènes par méthode d’immunofluorescence, de Western Blot et de réaction de polymérisation en chaîne quantitative en temps réel (qRT-PCR). Nous avons établi trois lignées des cellules épithéliales de l’oropharynx (HNOE) à partir d’échantillons tissulaires prélevés lors d’amygdalectomie (HNOE42, HNO45, HNOE46). Les cellules transduites avec le lentivirus exprimant le promoteur fort CMV/TO de l’oncogène RasV12 ont présenté un changement morphologique compatible avec une sénescence prématurée induite par l’oncogène Ras. En exprimant des quantités plus faibles du RasV12 mutant, la lignée cellulaire HEKn hTERT-E6-E7 PGK RasV12 a réussi à échapper à la sénescence induite par l’oncogène Ras. La population cellulaire exprimant HEKn hTERT-E6-E7-PGK RasV12 a présenté un phénotype malin en culture et à l’étude d'invasion, mais n’a pas démontré de résultats positifs à l’étude de croissance sans ancrage en agar mou ni en xénogreffe en souris immunodéficientes. Conclusion : Nos résultats démontrent qu’en présence des oncogènes viraux E6 et E7, il y a un troisième mécanisme suppresseur de tumeur qui médie la sénescence induite par l’oncogène Ras. Nous avons identifié que la présence de E6 seule ne suffit pas à immortaliser les kératinocytes primaires humains (HEKn). Nous n’avons pas réussi à créer un modèle in vitro de carcinogenèse pour les cancers de l’oropharynx induits par le VPH. / Background: Human papillomavirus (HPV) is present in almost 50% of all oropharyngeal cancers. The oncogenic potential of HPV is encoded by the E6 and E7 oncoproteins, which act by modulating different genes, including tumour suppressor genes p53 and pRb. The process of inactivation of p53 and pRb is largely responsible for the genomic instability that contributes to malignant transformation of cells. HPV-positive cancer cells show an alteration in their DNA Damage Response (DDR) signalling pathway that allows them to inhibit key tumour suppressor genes and to ignore DNA damage signals. Hypothesis and objectives: We believe that these DDR defects can be exploited to preferentially sensitize cancerous cells to radiotherapy by using a defined cell culture model. We propose to characterize a defined cell culture model for HPV induced oropharyngeal cancer. Derive isogenic cell culture lines from primary skin keratinocytes and oropharyngeal epithelial cells. and to validate the carcinogenesis of our model in vitro and in vivo. Methods: We propose to use primary skin keratinocytes and oropharyngeal epithelial cells which will be sequentially modified by transduction using a Gateway Lentiviral System to present the mutations associated with HPV induced oropharyngeal cancer. The cells will be modified with lentivirus encoding the human telomerase (hTERT), E6, E7 and Ras oncogenes. To validate the in vitro carcinogenesis of our model, we will assess anchorage independent growth and invasiveness by means of soft agar medium and matrigel studies. To assess in vivo tumorigenicity, the transformed cell populations will be introduced into immunodeficient mice. Results: We constructed recombinant lentivector plasmids using traditional cloning and Gateway recombination methods. Using the constructed lentivectors, we generated lentiviruses encoding the catalytic subunit for human telomerase (hTERT), the E6 and E7 viral oncogenes and Ras oncogene. Primary keratinocytes and oropharyngeal epithelial cells were infected successively by transduction with the above-mentioned lentiviruses and then underwent selection. We validated the expression of our transgenes by methods of immunofluorescence, Western blot and real-time quantitative polymerase chain reaction (qRT-PCR). We have successfully established and kept in culture three lines of epithelial oropharyngeal cells (HNOE42, HNOE45, HNOE46) from tissue samples collected during tonsillectomy. Cells transduced with lentivirus expressing CMV/TO, a strong promoter for the RasV12 oncogene, showed morphological changes compatible with premature Ras oncogene induced senescence. Cell line HEKn hTERT-E6-E7 PGK RasV12 managed to escape Ras oncogene induced senescence by expressing lower amount of mutated RasV12. The HEKn hTERT-E6-E7-PGK RasV12 cell line presented a malignant phenotype in culture and on matrigel invasion assay. However, soft agar assay for anchorage independent cell growth and xenograft assay in immunodeficient mice were both negative for tumorigenicity. Conclusion: Our results demonstrate that in the presence of E6 and E7, a third tumor suppressor mechanism mediates Ras oncogene induced senescence. Furthermore, we have found that the presence of E6 alone is not sufficient to immortalize primary human keratinocytes (HEKn). We have not managed to create an in vitro carcinogenesis cell culture model for HPV induced oropharyngeal cancer.

O consumo de álcool vem sendo associado a um aumento do risco de câncer e a uma situação de estresse oxidativo. Os metabólitos responsáveis por tais processos permanecem em discussão. Neste trabalho, caracterizamos novos metabólitos radicalares do etanol e examinamos suas interações com ácidos nucléicos. Primeiramente, demonstramos que os radicais 1-hidroxietila e 2-hidroxietila produzidos durante a oxidação do etanol por sistemas Fenton alquilam DNA e RNA in vitro produzindo os adutos 8-(1-HE)Gua e 8-(2-HE)Gua, respectivamente. Esses adutos foram sintetizados e caracterizados quimicamente. Também, demonstramos que acetaldeído, o principal metabólito do etanol, é oxidado por sistemas Fenton, peroxinitrito, xantina oxidase, partículas submitocondriais e ratos a radicais acetila e metila. Esses radicais foram caracterizados e seus mecanismos de formação elucidados, pelo menos in vitro. A possibilidade do radical 1-hidroxietila alquilar ácidos nucléicos in vivo foi também examinada. Inesperadamente, o aduto 8-(1-HE)Gua foi detectado em RNA e DNA do fígado de ratos controle e seus níveis não foram significativamente alterados após administração aguda de etanol. Esses resultados sugerem que os radicais 1-hidroxietila, acetila e metila são importantes metabólitos do etanol in vivo mas atacam preferencialmente outras biomoléculas que não ácidos nucléicos. / Alcohol consumption has been associated with increased cancer risk and an oxidative stress condition. Ethanol metabolites responsible for these processes remain debatable. Here, we characterized novel radical metabolites of ethanol and examined their interactions with nucleic acids. First, we demonstrated that the 1-hydroxyethyl and 2-hydroxyethyl radical produced from ethanol oxidation by Fenton systems alkylated DNA and RNA in vitro to produce 8-(1HE)Gua and 8-(2-HE)Gua, respectively. Both adducts were synthesized and structurally characterized. Next, we demonstrated that acetaldehyde, the main ethanol metabolite, is oxidized by Fenton systems, peroxynitrite, xanthine oxidase, submitochondrial particles and whole rats to acetyl and methyl radicals. These radicals were characterized and their production mechanisms in vitro elucidated. The possibility of the 1-hydroxyethyl radical alkylating nucleic acids in vivo was also examined. Unexpectedly, the adduct 8-(1-HE)Gua was detected in RNA and DNA from liver of control rats and their levels were not increased by acute ethanol treatment. Overall, the results suggest that the radicals 1-hydroxyethyl, acetyl and methyl are important ethanol metabolites in vivo but they preferentially attack biomolecules other than nucleic acids.

Como neoplasia maligna que mais acomete a cavidade oral, o carcinoma epidermóide gera infinidade de estudos acerca de sua gênese e progressão. O variado perfil genético e protéico observado leva a freqüente insucesso nas terapias adotadas, contribuindo para pobres prognósticos. Este estudo visa compreender melhor o papel da proteína Akt, tida como chave para a proliferação de diversas neoplasias, frente ao estímulo das células derivadas de carcinoma epidermóide humano em cultura (HaCat, HN6, HN19, HN30, HN31) com EGF 10ng/ml e TGF β 5ng/ml. Para tanto, analisou-se a expressão de pAkt, ciclina D1, Bad, caspase-3 e PTEN, através de imunofluorescência, western-blot e imunoprecipitação. Os resultados mostraram aumento da expressão de pAkt e ciclina D1 frente ao tratamento com EGF, bem como diminuição de Bad e PTEN, com exceção de HN31. A imunoprecipitação revelou neste caso que pAkt previne a apoptose através de inativação direta de Bad. Já nas células tratadas com TGF β , obtivemos resultados diferentes do esperado para este supressor de tumor. A expressão de pAkt mostrou-se aumentada nas linhagens celulares, mas estável em HN19 e HN31. Ciclina D1 mostrou aumento em HN6 e HN30, manutenção em HaCat e HN19 e diminuição em HN31. HaCat mostrou queda dos níveis de caspase-3 e Bad, manutenção em HN6, aumento em HN30, aumento somente de Bad em HN31 e HN19 com níveis inalterados após o tratamento para ambas as proteínas. Estes achados sugerem o importante papel desempenhado pelo EGF nas linhagens de carcinoma epidermóide estudadas, e como esta via é importante candidata a ser visada em tratamentos quimioterápicos. A ação do TGF β mostrou discrepâncias, revelando seu comportamento dúbio frente os diversos tipos celulares, e sugerindo possível relação entre este receptor e a via do pAkt, o que requer estudos mais apropriados. A baixa ocorrência de apoptose também reforça esta possibilidade, mostrando como a via do Akt é essencial para a progressão neoplásica e pode estar relacionada a mais eventos celulares do que já sabido. / Squamous cell carcinoma raises a great interest regarding carcinogenesis and its proliferative pathways, due to the high incidence and poor prognosis. The broad genetic and proteic profiles contribute to this poor prognosis. The present study aims to better comprehend the role played by pAkt, key protein for the development of many neoplasms. Cell lines derived from oral squamous cell carcinoma (HaCat, HN6, HN19, HN30 and HN31) were induced with 10ng/ml EGF and 5ng/ml TGF β . The expressions of pAkt, cyclin D1, Bad, caspase-3 and PTEN were analyzed through immunofluorescence, western-blot and immunoprecipitation. Results showed higher pAkt and cyclin D1 expression after EGF treatment, as well as a decrease in Bad and PTEN levels, except for HN31. Immunoprecipitation revealed that pAkt prevents apoptosis through Bad direct inactivation. However, TGF β treatment revealed different results, from what expected for this tumor supressor. pAkt expression revealed to be increased in all cells lines, but stable for HN19 and HN31. HaCat exhibited decreased levels of caspase-3 and Bad, which were unaltered in HN6, augmented in HN30. HN31 revealed only Bad increased levels, and no alterations in HN19. These findings suggest the crucial role played by EGF stimulation in the studied cell lines, and a good candidate to be targeted by chemotherapeutical approaches. TGF β treatment showed discrepancies, revealing diverse behaviors in the different cell lines. An exhisting relation between TGF β receptors and pAkt pathway may not be discharged, requiring further studies. The low occurrence of apoptosis reinforces this possibility, showing how important is Akt and related pathways for neoplastic progression, and its possible relation to cellular events not described to date.

O carcinoma epidermóide (CE) representa mais de 90% das neoplasias malignas encontradas na boca. Em casos avançados, quando o controle locoregional já não é possível somente com o tratamento cirúrgico mais a radioterapia, a quimioterapia adjuvante e neoadjuvate torna-se uma importante modalidade de tratamento para aumentar a qualidade de vida e sobrevida desses pacientes. Eventos moleculares que ocorrem durante a carcinogênese assemelham-se àqueles observados no processo da inflamação. Dessa forma, o estudo de substâncias anti-inflamatórias pode ser um importante caminho para o desenvolvimento e aperfeiçoamento de novos agentes quimioterápicos para o câncer. O objetivo deste estudo foi verificar uma possível ação antineoplásica de 2 anti-inflamatórios naturais (óleos de Copaiba e Andiroba) e um sintético (Dexametasona) numa linhagem de carcinoma epidermóide de orofaringe (FaDu), além de verificar se há uma correlação da expressão da proteína NFkB (fator de transcrição de genes envolvidos nos processos de carcinogênese e inflamação) com a inibição da proliferação celular. Para tanto, foram feitas análises quantitativas (curvas de crescimento, curva de viabilidade celular e Western Blot) e qualitativas (imunofluorescência) antes e depois do tratamento celular com os fármacos. O grupo controle foi representado pelas mesmas células (FaDu) cultivadas na ausência dos fármacos pesquisados. Após tratamento foi observado diminuição do crescimento e da viabilidade celular promovida por todos os fármacos, porém com potenciais de ação diferentes. O óleo de Copaíba apresentou uma potente ação inibição da proliferação e indução de apoptose, este último verificado pela positividade do teste Tunel para células apoptóticas. O óleo de Andiroba e Dexametasona promoveram inibição da proliferação dessas células, mas não indução de apoptose, sendo que para o último fármaco a ação foi dependente da concentração e tempo. Também pôde-se observar uma diminuição da expressão e marcação nuclear do NFkB por western Blot e imunofluorescência, respectivamente, após tratamento com os três antiinflamatórios. Os óleos de Copaíba e Andiroba e a Dexametasona, anti-inflamatórios naturais e sintético, respectivamente, promoveram ação de inibição da proliferação celular da linhagem FaDu, tendo uma relação com os níveis diminuídos da proteína NFkB que é responsável pela regulação de genes envolvidos nos processos de proliferação e sobrevivência celular. / Squamous cell carcinoma represents more than 90% of oral cavity malignancies. In advanced cases, when locoregional control is not possible using only surgery and radiotherapy adjuvant chemotherapy may play an important role to improve the quality of life and survival of these patients. Molecular events that occur during carcinogenesis are similar to those observed in the inflammatory process. So, the study of anti-inflammatory substances may be an important way for the development of new chemotherapeutic drugs for cancer. The aim of this study was to analyze a possible antitumoral effect of 2 natural anti-inflammatory oils (Copaiba and Andiroba) and a synthetic drug (dexamethasone) in a cell lineage of oropharynx squamous cell carcinoma (FaDu). Moreover, we tried to correlate NFkB protein expression with the inhibition of cell proliferation. Drugs effects were evaluated through quantitative methods (Western Blot method, growth and cell viability curves) and qualitative analyses (Immunofluorescence methods) before and after cell treatment. The control group was represented by the same cells (FaDu) grown in the absence of the drugs studied. After treatment all drugs promoted reduced growth and cell viability but with different potential actions. Copaiba oil showed a potent anti-proliferation action and to be inductor of apoptosis; the latter checked by testing positive for Tunel apoptotic cells. Andiroba oil and Dexamethasone promoted inhibition of cell proliferation, but not induction of apoptosis. The Dexamethasone action was time and dose dependent. There was a decrease expression and nuclear staining of NFkB by Western Blot and Immunofluorescence methods, respectively, after treatment with three anti-inflammatory substances. Oils of Copaiba and Andiroba and the dexamethasone promoted inhibition of cell proliferation FaDu lineage, showing an association with the level of expression of NFkB, which regulate genes that are involved in proliferation and cell survival.

O processo da carcinogênese é provocado por múltiplos estágios, envolvendo desordens potencialmente malignas, iniciação, invasão, progressão e metástase. O prognóstico do carcinoma epidermoide de boca (CEB) ainda permanece desfavorável devido ao diagnóstico tardio. Para mitigar esta complicação, biomarcadores tem sido utilizados para ajudar no diagnóstico precoce e entender melhor a influência sobre a carcinogênese oral, onde vias de sinalização são ativadas, principalmente a PI3K/AKT. MIF foi relacionada a progressão de diversos tipos cânceres, porém pouco se sabe seu papel na evolução do CEB. Por isso, o objetivo deste estudo foi identificar e caracterizar através do padrão de expressão imuno-histoquímico proteínas participantes da via de sinalização de PI3K/AKT: AKT1 e PAKT e sua associação com a expressão de MIF em fragmento de mucosa, hiperqueratose sem e com displasia e CEB correlacionando com a progressão da doença e características clinico-demográficos. Foram utilizados 73 blocos de parafina, avaliados quanto à porcentagem da expressão de cada marcador e coletados os dados clínicos epidemiológicos referentes para correlaciona-los à imunomarcação. A imunonopositividade ocorreu nos casos de mucosa normal, sem e com displasia e CEB. Nos casos de mucosa normal foram positivos para PAKT (50%), AKT (60%), MIF (80%). Em sem displasia, foi observado imunomarcação para PAKT (50%) e MIF (50%). Com displasia houve marcação PAKT (81,81%) e MIF (81%). Nos espécimes de CEB ocorreu em PAKT(100%), AKT (95,23%) e MIF (90,5%). Todos os anticorpos tiveram alta expressão no CEB em comparação com a mucosa normal (p<0,0001), sem displasia (p<0,0001) e com displasia (p<0,0001). Observou-se também influência sobre o fator de risco como tabagismo, etilismo e etnia, respectivamente para os grupos sem displasia, CEB e com displasia. Assim, estas proteínas podem ser consideradas potenciais marcadores preditores do CEB. / The carcinogenesis process is caused by multiple stages, involving potentially malignant disorders, initiation, invasion, progression and metastasis. The prognosis of squamous cell carcinoma (CEB) remains unfavorable due to late diagnosis. To mitigate this complication, biomarkers have been used to aid in early diagnosis and better understand the influence on oral carcinogenesis, which are activated signaling pathways, particularly PI3K / AKT. MIF was related to progression of many types cancers, but its role in the evolution of CEB is little known. Therefore, the aim of this study was to identify and characterize by the expression pattern of immunohistochemical participants proteins signaling pathway PI3K / AKT: AKT1 and PAKT and its association with MIF expression in normal mucosa, hyperkeratosis with and without dysplasia and CEB correlating with the progression of the disease and clinical and demographic characteristics. 73 paraffin blocks were used, in which evaluated the percentage of expression of each marker and collected epidemiological clinical data to correlate them to immunostaining. The imunonopositividade occurred in cases of normal mucosa, hyperkeratosis with and without dysplasia. In cases of normal mucosa were positive for PAKT (50%), AKT (60%), MIF (80%). In no dysplasia, immunostaining was observed PAKT (50%) and MIF (50%). With dysplasia was marking PAKT (81.81%) and MIF (81%). In CEB specimens occurred in PAKT (100%), AKT (95.23%) and MIF (90.5%). All antibodies had high expression in the CEB compared to normal mucosa (p <0.0001) without dysplasia (p <0.0001), and dysplasia (p <0.0001). It was also observed influence on the risk factors such as smoking, alcohol consumption and the ethnicity, respectively, for with dysplasia groups, CEB and without dysplasia. Thus, these proteins can be considered potential early diagnostic markers of CEB.

Protein kinase A (PKA) is an important enzyme inside the body; it is responsible for phosphorylation of gene regulatory elements and thus regulation of gene expression inside the nucleus. Malfunction of PKA affects transcriptional and translational levels of cell signaling ligands, leading to abnormal activity of various signaling pathways. PKA holoenzyme is composed of two regulatory and two catalytic subunits; four main regulatory subunit isoforms (R1α, R1β, R2α and R2β) and four main catalytic subunit isoforms (Cα, Cβ, Cγ and Prkx) of PKA have been identified. Mutations in these subunits lead to altered total PKA activities and PKAT-I to PKAT-II ratios, leading to diseases both in human and mice. These diseases include Carney Complex (CNC), fibrous dysplasia (FD) and Cushing syndrome. We studied the effect of PKA subunit mutations on intracellular PKA activities, PKAT-I to PKAT-II ratios, and bone and adrenal gland phenotypes in transgenic mouse models. Firstly, we generated whole-body transgenic mice single or double heterozygous for PKA regulatory subunits. Tail vertebral bone lesions including osteosarcomas, osteochondromas and osteochondrosarcomas were found in these mice and we found that mutations in different PKA subunits affect bone lesion formation, new bone generation, and bone organization and mineralization in mouse tail vertebrae. Elevated Cβ subunit expression in Parkar1a+/-Prkar2a+/- and Prkar1a+/-Prkar2b+/-double heterozygous mice leads to a less severe vertebral bone lesion phenotype, an increased osteogenic activity and a better bone regeneration activity. We then studied mice with tissue specific knock out of Prkar1a, the gene coding for type I regulatory subunit, specifically in adrenal cortex (AdKO). AdKO mice developed pituitary-independent Cushing syndrome with increased PKA activity. They also demonstrated increased plasma corticosterone levels resistant to dexamethasone suppression. Dietary treatment of both mice with bone lesions and mice with adrenal lesions with COX2 inhibitor Celecoxib led to partial rescue of phenotypes; this is due to inhibition of the positive feedback loop between PKA signaling and inflamasome pathway at COX2 induction level by Celecoxib. / 蛋白激酶A（PKA）是人體中重要的蛋白酶， 它通過燐酸化基因調控元件來實現對細胞核內基因表達的調節。PKA異常影響細胞內信號傳遞因子的基因轉錄和蛋白翻譯水平，從而導致各細胞信號通路的異常活動。PKA全酶由兩個調節亞基和兩個催化亞基組成，目前已經發現的有四個調節亞基 (R1α, R1β, R2α 和R2β) 以及四個催化亞基(Cα, Cβ, Cγ和Prkx)。發生在這些亞基中的基因突變會改變總的PKA活動水平，PKA-I 和PKA-II的比例，在人類和實驗鼠中引起疾病。這些疾病包括卡尼綜合症 （CNC），骨纖維性發育不良（FD）和庫欣綜合症。我們在轉基因鼠模型中研究PKA亞基突變對細胞中PKA總活性， PKA-I和PKA-II比例的影響，以及由此帶來的骨和腎上腺表型的改變和病變。我們首先製造了有一個或兩個PKA亞基雜合性缺失的全身轉基因鼠。在這些轉基因鼠中，我們發現了包括骨肉瘤，骨軟骨瘤和骨軟骨肉瘤在內的尾椎骨病變。研究發現在不同PKA亞基中的基因變異對實驗鼠尾椎骨病變的發生，新骨的形成和骨的結構和纖維化均有影響。在Prkar1a+/-Prkar2a+/-和Prkar1a+/-Prkar2b+/-實驗鼠中我們發現了較高的Cβ催化亞基表達，這兩個基因型因此具有更輕度的骨病變和更強的骨再生能力。我們繼續研究了在腎上腺中敲除了標記PKA 第一調節亞基的Prkar1a基因的實驗鼠 （AdKO）。AdKO實驗鼠中產生了與垂體無關的庫欣綜合症，並伴隨PKA活性的增加。它們還表現出耐地塞米松抑制的血漿皮質酮水平增加。對骨病變或腎上腺病變的實驗鼠通過飲食進行COX2抑制劑塞來昔布的治療可以部分緩解病變表型。這是由對PKA和炎性體的正反饋機制在COX2誘導步驟的抑制造成的。 / Liu, Sisi. / Thesis Ph.D. Chinese University of Hong Kong 2015. / Includes bibliographical references (leaves 115-130). / Abstracts also in Chinese. / Title from PDF title page (viewed on 09, September, 2016). / Detailed summary in vernacular field only.

L’agence internationale de recherche sur le cancer (IARC) a indiqué que le travail posté qui provoquait une disruption circadienne était probablement cancérogène chez l’Homme. Ainsi, une perturbation expérimentale sévère du système circadien accélère-t elle la progression tumorale et pourrait favoriser la cancérogénèse. Durant ma thèse, j’ai démontré que la disruption circadienne résultant d’une mutation ou d’une mise au silence des gènes de l’horloge Per ou Cry accélérait la cancérogénèse hépatique induite par la diéthylnitrosamine, en favorisant l’instabilité génomique, la prolifération cellulaire, et l’inflammation. J’ai montré que l’alimentation programmée ou la dexaméthasone modifiaient la régulation circadienne de ces trois caractéristiques du cancer, suggérant ainsi qu’une intervention thérapeutique ciblant le système circadien pourrait prévenir la cancérogénèse. J’ai ainsi mis en évidence le contrôle circadien de trois mécanismes moléculaires de la cancérogenèse précoce et proposé deux interventions ciblant l’horloge circadienne dans un but de prévention de la cancérogenèse. / The International Agency for Research on Cancer (IARC) concluded that “shift-work that involves circadian disruption is probably carcinogenic to humans”. Severe disruption alteration accelerated tumor progression and enhanced carcinogenesis. During my PhD, I demonstrated that circadian disruption resulting from mutation of Per and Cry clock genes accelerated liver carcinogenesis induced by diethylnitrosamine through promoting genomic instability, cellular proliferation, and inflammation. I showed that meal timing or dexamethasone altered circadian regulation of these three characteristics of cancer, suggesting a therapeutic intervention targeting the circadian system could prevent carcinogenesis. I have thus demonstrated the circadian control of three molecular mechanisms of early carcinogenesis and proposed two interventions targeting the circadian clock for liver carcinogenesis prevention.