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Der Cholesterin-Stoffwechsel ist sehr streng auf zellulärer Ebene reguliert und ist essentiell für das Zellwachstum. MicroRNAs (miRNAs), eine Klasse nicht-kodierender RNAs, wurden als kritische Regulatoren der Genexpression identifiziert und entfalten ihre Wirkung vorwiegend auf posttranskriptioneller Ebene. Aktuelle Arbeiten aus der Gruppe um Fernández-Hernando haben gezeigt, dass hsa-miR-33a und hsa-miR-33b, miRNAs die in den Intronsequenzen der Gene für die Sterol-regulatorischen Element- Bindungsproteine (SREBP-2 und SREBP -1) lokalisiert sind, den Cholesterin-Stoffwechsel im Einklang mit ihren Wirtsgenen regulieren. Gleichermaßen inhibiert miR-33 Schlüsselenzyme in der Regulation der Fettsäureoxidation, einschließlich CROT, CPT1A, HADHB, SIRT6, AMPKα, genauso wie IRS2, eine wesentliche Komponente des Insulin-Signalwegs in der Leber. Diese Studie zeigt, dass hsa-miR-33 Familienmitglieder nicht nur Gene in Cholesterin- und Fettsäure-Stoffwechsel sowie Insulin-Signalwege regulieren, sondern zusätzlich die Expression von Genen des Zellzyklus und der Zellproliferation modulieren. miR-33 inhibiert die Expression der CDK6 und CCND1, wodurch sowohol die Zellproliferation als auch die Zellzyklusprogression verringert wird. Die Überexpression von miR-33 induziert einen signifikanten G1 Zellzyklusarrest. Durch eine Inhibierung der miR-33 Expression mittels 2''F/MOE-modifiziert Phosphorothioat-Backbone Antisense-Oligonukleotiden, wird die Leberregeneration nach partieller Hepatektomie (PH) in Mäusen verbessert, was auf eine wichtige Rolle für miR-33 in der Regulation der Hepatozytenproliferation während der Leberregeneration hinweist. Zusammengefasst zeigen diese Daten, dass Srebf/miR-33 Locus kooperieren, um Zellproliferation und Zellzyklusprogression zu regulieren, und könnte somit auch relevant für die menschliche Leberregeneration sein. / Cholesterol metabolism is tightly regulated at the cellular level and is essential for cellular growth. Cellular imbalances of cholesterol and fatty acid metabolism lead to pathological processes, including atherosclerosis and metabolic syndrome. MicroRNAs (miRNAs), a class of noncoding RNAs, have emerged as critical regulators of gene expression acting predominantly at posttranscriptional level. Recent work from Fernández-Hernando´s group and others has shown that hsa-miR-33a and hsa-miR-33b, miRNAs located within intronic sequences of the sterol regulatory element-binding protein (SREBP-2 and SREBP-1) genes, respectively, regulate cholesterol metabolism in concert with their host genes. Similarly, miR-33 targets key enzymes involved in the regulation of fatty acid oxidation including CROT, CPT1A, HADHB, SIRT6 and AMPKα, likewise, IRS2, an essential component of the insulin- signaling pathway in the liver. This study shows that hsa-miR-33 family members not only regulate genes involved in cholesterol and fatty acid metabolism and insulin signaling, but in addition modulate the expression of genes involved in cell cycle regulation and cell proliferation. Thus, miR-33 inhibited the expression of CDK6 and CCND1, thereby reducing cell proliferation and cell cycle progression. Over-expression of miR-33 induced a significant G1 cell cycle arrest and most importantly, inhibition of miR-33 expression using 2’F/MOE-modified phosphorothioate backbone antisense oligonucleotides improved liver regeneration after partial hepatectomy (PH) in mice, suggesting an important role for miR-33 in regulating hepatocyte proliferation during liver regeneration. Altogether, these data establish that Srebf/miR-33 locus may co-operate to regulate cell proliferation, cell cycle progression and may also be relevant to human liver regeneration.

Ganoderma lucidum is a popular herbal medicine used in China to promote health. Modern studies have disclosed that the active ingredients of Ganoderma can exhibit several effects, including antitumor effects and immunomodulation. The present study evaluated the antitumor effects of self-prepared Ganoderma extracts and spores oil, and investigated the possible underlying mechanisms by observing the effects of the extracts and oil on topoisomerases and the cell cycle. The results showed that Ganoderma extracts and spores oil presented dose-dependent inhibitory effects on tumor cells. The half maximal inhibitory concentration (IC50) values of Ganoderma extracts on HL60, K562 and SGC-7901 cells for 24 h were 0.44, 0.39 and 0.90 mg/ml, respectively; for Ganoderma spores oil, the IC50 values were 1.13, 2.27 and 6.29 mg/ml, respectively. In the in vivo study, the inhibitory rates of Ganoderma extracts (4 g/kg/d, intragastrically) on S180 and H22 cells were 39.1 and 44.6%, respectively, and for Ganoderma spores oil (1.2 g/kg/d, intragastrically) the inhibitory rates were 30.9 and 44.9%, respectively. Ganoderma extracts and spores oil inhibited the activities of topoisomerase I and II. Ganoderma spores oil was shown block the cell cycle at the transition between the G1 and S phases and induce a marked decrease in cyclin D1 levels in K562 cells, with no significant change in cyclin E level. These results suggest that the Ganoderma extracts and spores oil possessed antitumor effects in the in vitro and in vivo studies. The antitumor mechanisms of the extracts and spores oil were associated with inhibitory effects on topoisomerase I and II activities, and for Ganoderma spores oil, the antitumor effects may also be associated with decreased cyclin D1 levels, thus inducing G1 arrest in the cell cycle.

Celecoxib é um antiinflamatório não esteroidal (AINE), inibidor seletivo da ciclooxigenase-2 (COX-2) usado em pesquisas recentes como agente anticarcinogênico. Os seus efeitos anti-neoplásicos dependem por um lado da sua capacidade de inibir a COX-2, mas por outro lado também age por mecanismos que independem da COX-2, em resumo o seu mecanismo de ação ainda não é completamente conhecido. O objetivo desta tese foi estudar os efeitos do celecoxib sobre as taxas de apoptose e os índices de proliferação celular de quatro linhagens celulares, Hn-6, Hn-19, Hn-30, Hn-31, de CECP e uma linhagem de queratinócitos mutada (HaCat), além de verificar se há correlação entre a expressão das proteínas COX-2, pAkt, ß-catenina, CD1 e NFKB e a inibição da proliferação celular. As células foram divididas em dois grupos: a, grupo controle; b, células cultivadas tratadas com celecoxib. A análise da expressão das proteínas pAkt, NFKB, ß-catenina, COX-2 e CD1 foi feita através da técnica de Western-blot. A indução de apoptose foi estudada com o Kit de Anexina. A proliferação celular foi monitorada através de curva de crescimento, com contagem celular na câmara de Neubauer e com o teste de viabilidade celular (Kit Cell Titer96) e a localização intracelular das proteínas foi avaliada por imunofluorescência. Os resultados mostraram significante aumento no índice celular de apoptose e diminuição da proliferação celular. Após o tratamento com celecoxib, a imunofluorescência mostrou que a proteína CD1 teve diminuição da expressão nuclear, a ß-catenina exibiu discreto aumento citoplasmático, o pAkt também passou a ser expresso no citoplasma da Hn6, enquanto as outras proteínas estudadas mantiveram o mesmo padrão de localização na célula. O western blot complementou os resultados da imunofluorescência indicando uma diminuição nos níveis de CD1. / Celecoxib, a cyclooxygenase-2 (COX-2) selective nonsteroidal anti-inflammatory drug, is a new anticarcinogenic agent. Its antitumor effects depend on the one hand on its COX-2-inhibiting potency, but on the other hand on COX-2-independent mechanisms, which until now have not been fully understood. The aim of this research was to study the effects of celecoxib in growth inhibition and apoptosis induction in four Head and Neck Squamous Cell Carcinoma (HNSCC) cell lines, HN6, HN19, HN30, HN31 and HaCat an immortalized keratinocyte cell line, and verify if there is a correlation between the growth inhibition and the expression of COX-2, pAkt, ß-catenin, CD1 and NFKB. The Western Blot was used to analyze the COX-2, pAkt, ß-catenin, CD1 and NFKB protein expression level. Apoptosis induction was studied with the Annexin V kit. The cell lines proliferation will be measured through a growth curve with the Neubauer chamber and MTS method (KitCell Titer96), the proteins intracellular site was assed by immunofluorescence technic. The same cell lines without any treatment were used as controls. Results showed a significant increase in apoptotic cells index, and growth inhibition in cell lines treated with celecoxib. The proteins localization was determined through immunofluorescence. In control group the CD1 was located mostly in nucleus, after treatment CD1 nuclear localization was reduced, it could also be noticed an increase in cytoplasmic expression of ß-catenin in all cell lines while pAkt cytoplasmic increase was present exclusevely in Hn6, the other proteins maintained their cellular localization,. The Western Blot results showed considerable reduction in CD1 levels with exception of Hn19 cell line.

Celecoxib é um antiinflamatório não esteroidal (AINE), inibidor seletivo da ciclooxigenase-2 (COX-2) usado em pesquisas recentes como agente anticarcinogênico. Os seus efeitos anti-neoplásicos dependem por um lado da sua capacidade de inibir a COX-2, mas por outro lado também age por mecanismos que independem da COX-2, em resumo o seu mecanismo de ação ainda não é completamente conhecido. O objetivo desta tese foi estudar os efeitos do celecoxib sobre as taxas de apoptose e os índices de proliferação celular de quatro linhagens celulares, Hn-6, Hn-19, Hn-30, Hn-31, de CECP e uma linhagem de queratinócitos mutada (HaCat), além de verificar se há correlação entre a expressão das proteínas COX-2, pAkt, ß-catenina, CD1 e NFKB e a inibição da proliferação celular. As células foram divididas em dois grupos: a, grupo controle; b, células cultivadas tratadas com celecoxib. A análise da expressão das proteínas pAkt, NFKB, ß-catenina, COX-2 e CD1 foi feita através da técnica de Western-blot. A indução de apoptose foi estudada com o Kit de Anexina. A proliferação celular foi monitorada através de curva de crescimento, com contagem celular na câmara de Neubauer e com o teste de viabilidade celular (Kit Cell Titer96) e a localização intracelular das proteínas foi avaliada por imunofluorescência. Os resultados mostraram significante aumento no índice celular de apoptose e diminuição da proliferação celular. Após o tratamento com celecoxib, a imunofluorescência mostrou que a proteína CD1 teve diminuição da expressão nuclear, a ß-catenina exibiu discreto aumento citoplasmático, o pAkt também passou a ser expresso no citoplasma da Hn6, enquanto as outras proteínas estudadas mantiveram o mesmo padrão de localização na célula. O western blot complementou os resultados da imunofluorescência indicando uma diminuição nos níveis de CD1. / Celecoxib, a cyclooxygenase-2 (COX-2) selective nonsteroidal anti-inflammatory drug, is a new anticarcinogenic agent. Its antitumor effects depend on the one hand on its COX-2-inhibiting potency, but on the other hand on COX-2-independent mechanisms, which until now have not been fully understood. The aim of this research was to study the effects of celecoxib in growth inhibition and apoptosis induction in four Head and Neck Squamous Cell Carcinoma (HNSCC) cell lines, HN6, HN19, HN30, HN31 and HaCat an immortalized keratinocyte cell line, and verify if there is a correlation between the growth inhibition and the expression of COX-2, pAkt, ß-catenin, CD1 and NFKB. The Western Blot was used to analyze the COX-2, pAkt, ß-catenin, CD1 and NFKB protein expression level. Apoptosis induction was studied with the Annexin V kit. The cell lines proliferation will be measured through a growth curve with the Neubauer chamber and MTS method (KitCell Titer96), the proteins intracellular site was assed by immunofluorescence technic. The same cell lines without any treatment were used as controls. Results showed a significant increase in apoptotic cells index, and growth inhibition in cell lines treated with celecoxib. The proteins localization was determined through immunofluorescence. In control group the CD1 was located mostly in nucleus, after treatment CD1 nuclear localization was reduced, it could also be noticed an increase in cytoplasmic expression of ß-catenin in all cell lines while pAkt cytoplasmic increase was present exclusevely in Hn6, the other proteins maintained their cellular localization,. The Western Blot results showed considerable reduction in CD1 levels with exception of Hn19 cell line.

Introdução: A ciclina D1 constitui um importante regulador do ciclo celular e pode funcionar como co-regulador de transcrição. A superexpressão da ciclina D1 tem sido associada ao desenvolvimento e progressão do câncer. A degradação irregular da ciclina D1 pode ser responsável pelos seus níveis elevados em algumas neoplasias malignas. A ciclina D1, além disso, modula indiretamente a estrutura da cromatina e transcrição de genes envolvidos na proliferação e diferenciação. Mutações, amplificação e superexpressão da ciclina D1, que alteram a progressão do ciclo celular, são observadas frequentemente em várias apresentações de neoplasias malignas, incluindo o carcinoma epidermóide de laringe, e as elucidações inferidas destas observações podem trazer melhor entendimento à oncogênese. Objetivo: O objetivo deste estudo foi comparar a expressão imunoistoquímica de ciclina D1 e a ocorrência de metástase linfática em estádios III e IV de carcinoma epidermóide de laringe. Métodos: Estudo retrospectivo, coorte longitudinal, por avaliação imunoistoquímica e quantificação digital da imunoexpressão nuclear e citoplasmática de ciclina D1 em espécimes de tumor preservados em parafina oriundos de pacientes consecutivos submetidos à cirurgia oncológica radical, entre 1999 e 2004. A sobrevida global dos pacientes foi avaliada, bem como a idade, sexo, tabagismo, estado de comprometimento linfático, grau de diferenciação e estadiamento (pTNM). A análise estatística teve como significância valores de p< 0.05. A curva de sobrevida foi elaborada utilizando o método de Kaplan-Meier. Resultados: Houve imunomarcação citoplasmática em 566 (1,2%) células, imunomarcação nuclear em 13788 (29,6%) células, a relação do IPc e IPn foi de 0,007 (0,7%), ausência de imunomarcação celular foi observada em 32210 (69,1%) células, perfazendo um total de 46554 (100%) células investigadas. Entre os 28 (59,5%) casos que não apresentaram metástase linfática, o IPn foi de 26,8 (9,7 - 46,9) e o IPc foi de 0,1 (0 0,3); naqueles 19 (40,4%) em que foi observada metástase linfática, o IPn foi de 26,7 (16,7 39,0) e o IPc foi de 0,3 (0 - 1,0). Conclusões: Não houve associação estatisticamente significante entre expressão nuclear e citoplasmática de ciclina D1, em carcinoma epidermóide primário de laringe, e ocorrência de metástase linfática cervical, graus de diferenciação histológica, bem como recidiva loco-regional e metástase hematogênica. O presente estudo não subsidia a superexpressão de ciclina D1 como fator limitante de sobrevida global / Background: Cyclin D1 is an important regulator of cell cycle progression and can function as a transcriptional co-regulator. The overexpression of cyclin D1 has been linked to the development and progression of cancer. Abnormal cyclin D1 degradation appears to be responsible for the increased levels of cyclin D1 in several cancers. Recent findings have identified novel mechanisms involved in the regulation of cyclin D1 stability. Cyclin D1 belongs to the family of cyclin proteins which function as the regulatory subunits of cyclin/cyclin dependent kinase (Cdk) holoenzymes that regulate entry into and progression through the cell cycle. Cyclin D1 expression is induced upon stimulation by growth factors (e.g. EGF, IGF-I/II), aminoacids, hormones, and oncogenes such as Ras, Src, ErbB2, and SV40 T antigen. Cdk4 and Cdk6 can partner with cyclin D1 in early to mid-G1 phase to phosphorylate and inactivate the cell cycle inhibitory function of the retinoblastoma protein (pRB) in cooperation with cyclin E/Cdk2. Cyclin D1 is also known to modulate local chromatin structure and transcription of genes involved in proliferation and differentiation through CDK-independent association with histone acetylases (e.g. CBP, P/CAF) and deacetylases. Mutations, amplification or overexpression of cyclin D1, which alters cell cycle progression, are observed frequently in a variety of tumors, including laryngeal squamous cell carcinoma, and may contribute to oncogenesis. Methods: This was a retrospective study by immunohistochemical determination of cyclin D1 in fixated and paraffin-embedded tumour especimens from 47 consecutive patients with squamous cell carcinoma in larynx treated by curative oncological surgery from 1999 to 2004. Survival of patients was related to age, gender, nodal status and stage at termination of treatment. Significant differences were considered for p<0.05. Results: Cytoplasmic immunostain was observed in 566 (1,2%) cell, nuclear immunostain in 13788 (29,6%) cell, relationship between PIc and PIn was 0,007 (0,7%), absent cell immunostain was observed in 32210 (69,1%), and total 46554 (100%). Among 28 (59,5%) cases with no lymph node metastasis, PIn was 26,8 (9,7 - 46,9) and PIc was 0,1 (0 0,3); those 19 (40,4%) with lymph node metastasis, had a PIn of 26,7 (16,7 39,0) and PIc of 0,3 (0 -1,0). Conclusions: According to these results, it has been concluded that cyclin D1 showed nuclear and cytoplasmic expression in larynx squamous cell carcinoma; however, tumor cyclin D1 expression was not significantly associated with lymph node metastasis when quantified by quantitative or semiquantitative methods. Besides, cyclin D1 expression showed no influence in overall survival

Thesis (Ph. D.)--University of Washington, 2003. / Vita. Includes bibliographical references (leaves 69-77).

Thesis (Ph. D.)--University of Washington, 2003. / Vita. Includes bibliographical references (leaves 112-124).

Cyclin D1, a proto-oncogene, is required for progression from the G1 phase into the S phase of the cell cycle. Over-expression of cyclin D1 causes an increase in cell cycle progression and cell proliferation, implicating it in a variety of cancers including renal cell carcinoma (RCC). The rodent RCC cell model, QTRRE, and human RCC cell models, ACHN, 786-O and Caki-2, exhibit elevated levels of cyclin D1. Pentoxifylline (PTX), a non-specific phosphodiesterase inhibitor, is an FDA-approved hemorheologic agent used to treat intermittent claudication, stemming from peripheral vascular diseases, as well as other diseases involving defective locoregional blood flow. Treatment of QTRRE, ACHN, 786-O and Caki-2 with PTX caused a time- (0-24 hrs) and dose- (0-1.0 mg/mL) dependent decrease of cyclin D1 protein and p-Rb levels in whole cell lysate as well as cytosolic and nuclear fractions, albeit, to different extents within the models. Concomitant with cyclin D1 and p-Rb decrease, enhanced G1 phase cell cycle arrest was observed in the RCC models. Mechanistic studies in these RCC cell models were carried out to determine PTXs mechanism of action with regard to cyclin D1 protein level decrease. RT-PCR analysis showed no significant changes in cyclin D1 mRNA copy number in time- (0-24 hrs) and dose- (0-1.0 mg/mL) dependent PTX treatments. However, such treatments caused decrease in p-4EBP1 (Ser65), p-4EBP1 (Thr70), and p-4EBP1 (Thr37/46). Because PTX's ability to decrease cyclin D1 protein was prevented in the presence of the proteasome inhibitor, MG-132, studies were performed to determine whether cyclin D1 stability was decreased during PTX treatment. Cyclin D1 degradation is initiated by phosphorylation of residue Thr286 by GSK-3β. Inhibition of GSK-3β with LiCl or knockdown via siRNA in the presence of PTX failed to block cyclin D1 decrease. Moreover, PTX treatment in the presence of MG-132 revealed no significant increase in cyclin D1 p-Thr286 compared to control. Finally, using the protein synthesis inhibitor, CHX, PTX caused no significant decrease in cyclin D1 t₁/₂ (wt-HA and T286A-HA) compared to control. Sorafenib, a broad-spectrum (cRAF, bRAF, KIT, FLT-3, VEGFR-2, VEGFR-3, and PDGFR-β) kinase inhibitor, is FDA-approved for the treatment of RCC. Studies with sorafenib and PTX in the ACHN cell model were carried out to determine PTXs possible adjuvant role in inhibiting cell growth via cyclin D1 decrease and G1 phase arrest. MTS data showed PTX potentiates the anti-proliferative effects of sorafenib. PTX pre-treatment for 24 hrs was also lowered the effective dose of sorafenib from 50 μM to 5 μM. Further, ACHN xenograft tumor volumes from mice treated with PTX and sorafenib displayed significantly higher tumor growth inhibition compared to either drug treatment alone or vehicle. Finally, drug treated ACHN xenograft tissue displayed significantly lower cyclin D1, p-RB and p-4EBP1 levels. These results demonstrate a novel anti-cancer property of PTX and suggest its use as a possible adjuvant therapy in RCC treatment should be further explored.

<p>The majority of breast tumors express the estrogen receptor (ER), and more than half of these cancers also express the progesterone receptor (PR). While the actions of ER on breast cancer pathogenesis are well understood, those of PR are still unclear. The Women's Health Initiative trial in 2002 brought into focus the alarming result that women receiving both estrogen and progestins as hormone replacement therapy are at greater risk for breast cancer than women receiving estrogen alone. Thus, there is considerable interest in defining the mechanisms that underlie the pharmacological actions of progestins in the normal and malignant breast. </p><p>Progestins facilitate cell cycle progression through multiple mechanisms, one of which is the induction of phosphorylation of the tumor suppressor retinoblastoma (Rb) protein. Stimulation by growth factors induces the transcription of Cyclin D1 which in turn activates the cyclin dependent kinases (CDKs). The Cyclin D1- Cdk4/6 complex phosphorylates the Rb protein, leading to the release of E2F1, which then binds and activates other target genes, leading to G1-S transition of the cell cycle. Given the reported action of PR to activate MAPK signaling, we initially thought that the progestin-induced Rb phosphorylation was mediated by this pathway. However, we turned to an alternate hypothesis based on our data using MEK inhibitors demonstrating that this was not the case. </p><p>Given the primacy of Cyclin D1 in cell cycle control, we then turned our attention to defining the mechanism by which Cyclin D1 expression is regulated by PR. Interestingly, it was determined that progestin mediated up- regulation of Cyclin D1 is rapid, peaking at 6hrs post hormone addition followed by a decrease in expression reaching a nadir at 18hrs. Unexpectedly, we found that contrary to what has been published before, the induction of Cyclin D1 mRNA expression was a primary transcriptional event and we have demonstrated the specific interaction of PR with PREs (progesterone response elements) located on this gene. We have further determined that the half-life of Cyclin D1 mRNA is decreased significantly by progestin addition explaining how the levels of this mRNA following the addition of hormone are quickly attenuated. Thus, when taken together, our data suggest that progestins exert both positive and negative effects on Cyclin D1 mRNA, the uncoupling of which is likely to impact the pathogenesis of breast cancer</p><p>The observation that PR reduces the Cyclin D1 mRNA stability led us to investigate the effects of PR on RNA binding proteins, especially those which are involved in RNA stability. We discovered that PR induces the expression of several RNA binding proteins. Although the work to determine the effects of these RNA binding proteins on CyclinD1 mRNA stability is still ongoing, we have discovered a role for one of the PR-induced RNA binding proteins tristetraprolin (TTP), in the suppression of the inflammation pathway in breast cancer. We found that while TTP was not required for the PR-mediated decrease in Cyclin D1 mRNA stability, overexpression of this tumor suppressive protein was able to inhibit IL-1&#946;-mediated stimulation of inflammatory genes in our breast cancer model. Since it is established that the upregulation of the inflammatory pathway is oncogenic, we are currently exploring the intersection of PR and TTP-mediated signaling on the inflammation transcriptome in breast cancer. </p><p>Thus, collectively these data provide us with a better picture of the poorly understood actions of PR on breast cancer proliferation and tumorigenesis. We believe that further investigation of the studies developed in this thesis will lead to novel and better-targeted approaches to the use of PR as a therapeutic target in the clinic.</p> / Dissertation