Thesis (doctoral)--Lund University, 1998. / Thesis statement on t.p. verso. Includes bibliographical references.

Thesis (M.S.)--Ball State University, 2009. / Title from PDF t.p. (viewed on June 07, 2010). Includes bibliographical references (p. 141-147).

Thesis (doctoral)--Rijksuniversiteit te Utrecht, 1963. / "Appendices" (1 v.) inserted in pocket at end. eContent provider-neutral record in process. Description based on print version record.

Thesis (Ph. D. in Chemistry)--Vanderbilt University, Aug. 2005. / Title from title screen. Includes bibliographical references.

Thesis (Ph. D.)--Miami University, Dept. of Chemistry and Biochemistry, 2004. / Title from second page of PDF document. Includes bibliographical references.

Thesis (Ph. D.)--Illinois State University, 2005. / Title from title page screen, viewed September 27, 2006. Dissertation Committee: Brian J. Wilkinson (chair), Radheshyam K. Jayaswal, Wade A. Nichols, Alan J. Katz, David L. Williams. Includes bibliographical references and abstract. Also available in print.

Thesis (MSc (Mathematics))--University of Stellenbsoch, 2009. / Please refer to full text for abstract

Heat shock protein 90 (HSP90), a conserved molecular chaperone, has become a potential molecular target for cancer therapeutics. HSP90 inhibition (HSP90i) causes inhibition of several oncogenic pathways simultaneously and leads to anti-cancer activities in multiple cancers including in triple-negative breast cancer (TNBC). TNBC is a subtype of breast cancer with poor prognosis and lack of approved targeted therapies. Although HSP90i has shown promising initial clinical data, resistance to HSP90i can still arise in TNBC patients and its resistance mechanisms are not yet understood. In this study, using an in vitro system, we report for the first time the isolation of TNBC cells with acquired resistance to HSP90i. Proteome and whole transcriptome profiling, and a bioactive small molecule screen were performed to identify the molecular basis of resistance to HSP90i and potential therapeutic approaches to overcome acquired resistance to HSP90i in TNBC cells. Two independent HSP90i-resistant clones were acquired through prolonged exposure of a TNBC cell line (Hs578T) to HSP90i. The clones showed significant resistance to HSP90i, notably to resorcinol-based HSP90i. The HSP90i-resistant clones also shared genomic sequence variants, suggesting a pre-existing population of resistant cells within the parental cells. We demonstrate that upregulated expression of UGT1A9, possibly due to an increased intrinsic oxidative stress, is associated with acquired resistance to resorcinol-based HSP90i in TNBC cells, and sensitivity to HSP90i can be restored with a competitive inhibitor of UGT1A9. The HSP90i-resistant clones also exhibited slower growth and upregulated IL6- mediated JAK2-STAT3 survival signalling pathway, which might contribute to the crossresistance to chemotherapeutics and other targeted therapies seen in the clones. Finally, we demonstrate that inhibition of JAK2-STAT3 signalling pathway is able to increase the cytotoxic effects of HSP90i to TNBC cells. We conclude that by using in vitro assays, we are able to identify potential mechanisms of acquired resistance to HSP90i in TNBC cells. We propose that expression of UGT1A9 or STAT3 might be a potential biomarker of sensitivity to HSP90i in TNBC cells. A combined inhibition of HSP90 and JAK2 might be a potential therapeutic approach for the development of effective targeted therapies in TNBC patients.

abstract: Infectious diseases are a leading cause of death worldwide. With the development of drugs, vaccines and antibiotics, it was believed that for the first time in human history diseases would no longer be a major cause of mortality. Newly emerging diseases, re-emerging diseases and the emergence of microorganisms resistant to existing treatment have forced us to re-evaluate our optimistic perspective. In this study, a simple mathematical framework for super-infection is considered in order to explore the transmission dynamics of drug-resistance. Through its theoretical analysis, we identify the conditions necessary for the coexistence between sensitive strains and drug-resistant strains. Farther, in order to investigate the effectiveness of control measures, the model is extended so as to include vaccination and treatment. The impact that these preventive and control measures may have on its disease dynamics is evaluated. Theoretical results being confirmed via numerical simulations. Our theoretical results on two-strain drug-resistance models are applied in the context of Malaria, antimalarial drugs, and the administration of a possible partially effective vaccine. The objective is to develop a monitoring epidemiological framework that help evaluate the impact of antimalarial drugs and partially-effective vaccine in reducing the disease burden at the population level. Optimal control theory is applied in the context of this framework in order to assess the impact of time dependent cost-effective treatment efforts. It is shown that cost-effective combinations of treatment efforts depend on the population size, cost of implementing treatment controls, and the parameters of the model. We use these results to identify optimal control strategies for several scenarios. / Dissertation/Thesis / Ph.D. Applied Mathematics for the Life and Social Sciences 2011

O desenvolvimento de resistência a múltiplas drogas na terapêutica do câncer é um importante obstáculo para o tratamento efetivo. Os mecanismos de resistência a múltiplas drogas ocasionam a redução intracelular de agentes quimioterápicos e, por conseqüência, estão envolvidos no fracasso no tratamento do câncer. Os principais genes envolvidos neste fenômeno são: o gene MDR1(multiple drug resisctance), que codifica uma glicoproteína de alto peso molecular, a P-gp; o gene MRP1, que codifica uma glicoproteína de 190 Kda, denominada proteína associada à resistência a múltiplas drogas; e o gene da LRP (proteína relacionada à resistência de pulmão). Alguns estudos sugerem que o colesterol pode estar envolvido diretamente com o fenômeno de resistência a múltiplas drogas, e que os lipídeos podem influenciar várias e complexas funções no MDR, por afetarem o transporte de drogas através da membrana plasmática. Além disso, células tumorais tem maior necessidade de colesterol devido a uma taxa de multiplicação mais elevada que as células normais. Neste estudo analisou-se a expressão dos genes MDR1, MRP1 e LRP em células de sarcoma uterino resistentes à doxorrubicina, e a influência de lipoproteínas. Houve aumento da expressão dos genes MDR1, MRP1 e LRP nas células tratadas com a LDL, sendo mais expressivo o gene MDR1. A HDL diminuiu a expressão dos genes MRP1 e LRP. No entanto, o gene MDR1 teve sua expressão diminuída somente em concentrações maiores. As células cultivadas em meio sem soro fetal apresentaram um elevado aumento na expressão destes genes. Em conclusão, as lipoproteínas podem modular a expressão dos genes MDR1, MRP1 e LRP e, assim, atuar na resistência a múltiplas drogas. / The development of multidrug resistance in anticancer therapy is an obstacle in the efficiency of the treatment. The multidrug resistance mechanism causes reduction of intracellular chemotherapeutical drugs. Therefore, it leads to treatment failure. There are three main multidrug resistance genes: MDR1, which codifies the P-gp (a high weight glycoprotein); MRP1, which codifies a 190 Kda glycoprotein; and, the LRP (lung resistance related protein) gene. Several reports suggest that cholesterol may be directly involved with the multidrug resistance phenomenon and that lipids may affect many complex functions in this regard, as the activity of the drug transport across the plasmatic membrane. Moreover, tumor cells have great cholesterol necessity due to the high cell multiplication rate. Here we described the MDR, MRP, LRP gene expression of a doxorubicin-resistant uterine sarcoma cell line under the influence of lipoproteins. LDL increased the expression of all genes, mainly MDR1. Treatment with HDL led to reduction of MRP and LRP expression. However, the MDR gene expression decreased only by higher concentrations of HDL. Cells grown in serumdeprived medium led to an increased expression of all the studied genes. Therefore, lipoproteins may modulate the MDR, MRP, LRP gene expression and, consequently, the cell resistance to drugs.