Multiple myeloma (MM) is a virtually incurable B cell malignancy of the bone marrow. One important part of tumor progression and an obstacle for successful therapy is resistance to apoptosis. To combat this resistance, the mechanisms of apoptosis and survival in MM must be better defined. In this thesis, we identified Fas up-regulation as a mechanism underlying interferon (IFN)-mediated sensitization to Fas-induced apoptosis in the MM cell line U-266-1970. IFN treatment induced activation of signal transducer and activator of transcription (Stat)1 but, intriguingly, also attenuated activation of MM survival factor Stat3. Exploring the role of Stat1 further, we established sub-lines of U-266-1970 with a stable over-expression of Stat1 and of its active mutant Stat1C. These sub-lines displayed a decreased expression and activation of Stat3, and an altered expression of apoptosis-related genes Harakiri, Bcl-2 and Mcl-1. In a drug library screening, Stat1 over-expression was associated with an increased sensitivity to Fas-induced apoptosis and, conversely, an increased resistance to several drugs, including the cyclin dependent kinase (cdk)1 inhibitor CGP74514A. We conclude that Stat1 over-expression does not confer a general resistance or sensitivity to apoptosis in MM, but may strongly affect the response to some specific drugs. We also explored the effects of picropodophyllin (PPP), an inhibitor of the insulin-like growth factor I (IGF-I) receptor tyrosine kinase (RTK), in MM. PPP selectively inhibited the IGF-I RTK activity without inhibiting the insulin RTK activity. Furthermore, PPP potently induced cell cycle arrest and apoptosis in all MM cell lines and patient samples tested, also in the presence of survival factors IGF-I and IL-6. We conclude that PPP has great therapeutic potential in MM Finally, we examined the expression and regulation of the inhibitors of apoptosis proteins (IAPs) in a panel of MM cell lines and patient samples. The glucocorticoid dexamethasone, which is used in MM therapy, induced a transient up-regulation and a subsequent down-regulation of c-IAP2, as well as a down-regulation of XIAP, possibly influencing the sensitivity to apoptosis induced by this drug. Supporting this notion, abrogation of IGF-IR signaling by PPP, which sensitizes MM cells to dexamethasone-induced apoptosis, enhanced the down-regulation of c-IAP2 and XIAP.

Diss. (sammanfattning) Linköping : Linköpings universitet, 2008. / Härtill 4 uppsatser.

Para verificar a expressão das proteínas Fas e Bcl-2 em linfócitos e suas correlações com a atividade da doença foram avaliados 38 pacientes com lúpus eritematoso sistêmico de início na infância e 25 controles sem doença autoimune. Observou-se que as porcentagens de linfócitos T CD3+ e CD8+ e linfócitos B que expressavam a proteína Fas e a intensidade média de fluorescência da proteína Bcl-2 nos linfócitos T CD3+, CD4+ e CD8+ dos pacientes com lúpus foram significativamente maiores quando comparadas aos controles. Os pacientes com doença ativa apresentavam porcentagens de linfócitos B que expressavam a proteína Fas significativamente maiores que os pacientes com doença inativa e os controles e houve correlação direta entre estas porcentagens e o SLEDAI (p=0.02, r=0.38) / In order to verify the expression of Fas and Bcl-2 proteins on lymphocytes and their relationship with disease activity 38 patients with juvenile-onset systemic lupus erythematosus and 25 healthy controls were studied. The measurements showed that percentages of lymphocytes T CD3+ and CD8+ and B lymphocytes positively stained for Fas antigen and mean fluorescence intensity of Bcl-2 on CD3+, CD4+ and CD8+ T cells from lupus patients were significantly increased compared to healthy controls. Lupus patients with active disease presented percentages of lymphocytes B positive for Fas antigen significantly higher compared to patients with inactive disease and healthy controls and there was a statistically significant direct correlation between these percentages and SLEDAI score (p=0.02, r=0.38).

Para verificar a expressão das proteínas Fas e Bcl-2 em linfócitos e suas correlações com a atividade da doença foram avaliados 38 pacientes com lúpus eritematoso sistêmico de início na infância e 25 controles sem doença autoimune. Observou-se que as porcentagens de linfócitos T CD3+ e CD8+ e linfócitos B que expressavam a proteína Fas e a intensidade média de fluorescência da proteína Bcl-2 nos linfócitos T CD3+, CD4+ e CD8+ dos pacientes com lúpus foram significativamente maiores quando comparadas aos controles. Os pacientes com doença ativa apresentavam porcentagens de linfócitos B que expressavam a proteína Fas significativamente maiores que os pacientes com doença inativa e os controles e houve correlação direta entre estas porcentagens e o SLEDAI (p=0.02, r=0.38) / In order to verify the expression of Fas and Bcl-2 proteins on lymphocytes and their relationship with disease activity 38 patients with juvenile-onset systemic lupus erythematosus and 25 healthy controls were studied. The measurements showed that percentages of lymphocytes T CD3+ and CD8+ and B lymphocytes positively stained for Fas antigen and mean fluorescence intensity of Bcl-2 on CD3+, CD4+ and CD8+ T cells from lupus patients were significantly increased compared to healthy controls. Lupus patients with active disease presented percentages of lymphocytes B positive for Fas antigen significantly higher compared to patients with inactive disease and healthy controls and there was a statistically significant direct correlation between these percentages and SLEDAI score (p=0.02, r=0.38).

No description available.

Diss. (sammanfattning) Linköping : Linköpings universitet, 2007. / Härtill 4 uppsatser.

MicroRNAs (miRNAs) sind endogenene kurze RNA-Moleküle, die zentrale Aufgaben bei der Regulation der eukaryotischen Zellhomöostase erfüllen. MiRNAs wurden bereits als potente Immunregulatoren beschrieben. Trotz dieser Erkenntnisse blieb die Rolle dieser kurzen RNA Moleküle in Infektionen mit Mycobacterium tuberculosis weitgehend unerforscht. Im Rahmen dieser Arbeit wurde ein miRNA-Expressionsprofil von Makrophagen generiert, die mit Mycobacterium tuberculosis infiziert waren. Dies ermöglichte die Identifizierung von miRNAs, welche bei der Infektion differenziell reguliert waren. Anhand eines ex-vivo-Modells von Todesrezeptor-induzierter Apoptose konnte gezeigt werden, dass miRNA-133b apoptoseresitente Zellen empfindlich gegen Tumornekrosefaktor-alpha (TNFalpha), TNF-related apoptosis-inducing ligand (TRAIL) oder CD95 ligand (Fas/APO1 ligand) induzierte Zytotoxizität machte. Eine umfassende Studie führte zur Identifizierung der anti-apoptotischen Proteine Fas apoptosis inhibitory molecule (FAIM) und glutathione-S-transferase pi (GSTP1) als direkte Zielgene für miRNA-133b. Desweiteren zeigte sich die Expression von Osteoprotegerin (OPG) und Fettsäuresynthase (FASN), als miRNA-133b abhängig. Dies unterstrich die pleiotrope Art der pro-apoptotischen Aktivität dieser miRNA. Die Expression von miRNA-133b wurde durch Mitglieder der Toll-like Rezeptor (TLR)-Familie aktiviert. MiRNA-133b Transfektion führte zu einer verstärkten Aktivierung des Transkriptionsfaktors nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kappaB). Diese resultierte in erhöhten Mengen an Interleukinen 6 und 8 (IL6/8). Diese Ergebnisse stellen die erste detaillierte Charakterisierung von miRNA-133b im Zusammenhang der Todesrezeptor-vermittelten Apoptose und der angeborenen Immunität dar. Die erforschten molekularen Wechselwirkungen ergänzen und bereichern das Verständnis über die regulatorischen molekularen Mechanismen, die mit der Tumorentstehung und Entzündung verbunden sind. / MicroRNAs (miRNAs) are endogenous short RNA molecules which perform essential tasks in the regulation of eukaryotic cell homeostasis. During the past few years miRNAs have emerged as very potent immune regulators. Despite the consequences of this discovery for our understanding of immune response regulation hitherto virtually nothing is known about miRNA function during innate immunity to Mycobacterium tuberculosis. Herein, a miRNA expression profile of human macrophages infected with Mycobacterium tuberculosis was generated. This led to the identification of miRNAs being differentially regulated during infection. By using an experimental ex-vivo model of death receptor (DR)-induced apoptosis it could be demonstrated that miRNA-133b rendered apoptosis-resistant cells sensitive to tumor necrosis factor-alpha (TNFalpha)-, TNF-related apoptosis-inducing ligand (TRAIL)- or CD95 ligand (Fas/APO1 ligand)-activated cytotoxicity. Comprehensive analysis led to the discovery of the anti-apoptotic proteins Fas apoptosis inhibitory molecule (FAIM) and glutathione-S-transferase pi (GSTP1) as direct miRNA-133b targets. Moreover, underlining the pleiotropic and synergistic nature of miRNA activity, the expression of osteoprotegerin (OPG) and fatty acid synthase (FASN) could be further proven as miRNA-133b dependent. Expression of miRNA-133b increased following innate immune activation by members of the Toll-like receptor (TLR) family. MiRNA-133b enhanced the activity of the transcription factor nuclear factor kappa-light-chain-enhancer of activated B cells (NF-kappaB). This translated into increased levels of the pro-inflammatory interleukins 6 and 8 (IL6/8). The results presented in this work represent the first detailed characterization of miRNA-133b in the context of DR-mediated apoptosis and innate immunity. The molecular interactions dissected herein improve the understanding of the regulatory processes associated with tumorigenesis and the immune response.

No description available.