Background: Metastatic melanoma remains a life-threatening disease because most tumours develop resistance in response to conventional treatment. Even though targeted drugs represent promising therapeutics, the clinical outcome remains poor, with high relapse rates coinciding with pronounced metastatic outgrowth. Therefore, successful therapy is still challenging, and alternative treatment options are demanded as first or second line therapy to overcome acquired resistance. In this context, cell death induction by the tumour-selective death ligand TRAIL (Tumour necrosis factor-Related Apoptosis-Inducing Ligand) might serve as an alternative single or co-treatment option. Unfortunately, melanoma cells were shown to stay largely resistant against conventional TRAIL treatment and the first-generation TRAIL-based therapeutics failed in clinical trials due to the limited therapeutic activity in patients. To overcome this therapeutic limitation, a second-generation hexavalent TRAIL receptor agonist IZI1551 has been developed showing increased bioactivity thereby enhancing the cytotoxic effects on cancer cells. Questions and Hypothesis. We hypothesized that cells that do not receive the full but only a sublethal drug-dose may not only be responsible for drug resistance but may also confer tumour relapse and metastatic outgrowth. By switching the signal transduction from pro-apoptotic to anti-apoptotic and pro-survival, these cells may foster an aggressive phenotype with enhanced proliferation and migration. Therefore, an in depth understanding of the underlying mechanisms of emerging drug resistance that may additionally trigger secondary metastasis formation is required to identify new therapeutic targets and alternative treatment options. Methodology. Melanoma cell lines were conditioned to the TRAIL receptor agonist IZI1551 and the expression of members of the anti-apoptotic NFκB and MAPK pathways as well as of the TRAIL receptor-driven apoptotic pathway were investigated by semi-quantitative Western-blot analysis. Protein expression/activation data of parental IZI1551-sensitive versus conditioned IZI1551-resistant melanoma cells were implemented into a network topology derived from literature. A Dynamic Bayesian Network (DBN) model was combined with a sophisticated regularisation strategy resulting in sparse and context-sensitive networks to identify cell line-specific deregulations within the signalling network. Predictions of the model were confirmed by siRNA-mediated knock down. Enhanced proliferation and migration of resistant-cells were investigated by proliferation, clonogenic, and scratch assays. Following the 2D studies, migration and invasion were monitored by confocal microscopy in 3D migration/invasion assays and 3D spheroids models. Expression of pro-metastatic cell adhesion molecules was evaluated by flow cytometry. In order to identify potential regulators of the aggressive phenotype, quantitative transcriptome analysis (RNA-seq) was performed. The therapeutic outcome of the new identified treatment options with IZI1551 alone or in combination with Smac mimetics or bortezomib was evaluated by cell death detection ELISA. Results. In this thesis, IZI1551 was shown to induce pronounced apoptotic cell death in melanoma cells compared to mutation specific targeted kinase inhibitors, as being used in the clinic. Comparing IZI1551-sensitive to IZI1551-resistant melanoma cells, the DBN model accurately predicted activation of NFκB in concert with upregulation of the anti-apoptotic protein XIAP to be the key mediator of IZI1551 resistance. Moreover, XIAP was identified to serve as a potential biomarker for TRAIL responsiveness. According to these findings, human melanoma cell lines were re-sensitised to TRAIL in vitro by co-application of the IAP antagonists Smac mimetics as well as bortezomib, a proteasome inhibitor currently used in cancer treatment. In addition, by triggering survival instead of apoptotic signalling pathways, resistant cells caused an aggressive phenotype with enhanced proliferation and migration/invasion into 3D collagen matrices, coinciding with upregulation of the cell adhesion molecules MelCAM and αVβ3 integrin, which are known to promote tumour progression and metastasis. Combining in silico studies of RNA-seq and protein expression data, YAP, an intracellular transducer of mechanical stimuli, and its upstream regulator FAK, a component of the focal adhesion complex, were identified as key promoters of proliferation and migration. Conclusions. Identification of new biomolecular markers or targets combining experimental and computational approaches is a promising avenue to assess the effects of drug combinations and to identify responders to selected combination therapies. In this thesis, IZI1551 was identified as an alternative treatment option for metastatic melanoma. Our data also suggest that XIAP expression may serve as a potential predictive marker for the sensitivity of tumour cells to TRAIL-induced apoptosis. Above this, we demonstrated that three alternative treatment options with IZI1551 in combination with Smac mimetics, bortezomib or FAK inhibitors may represent a promising approach for the treatment of TRAIL-resistant melanomas and to prevent undesired metastatic outgrowth.

Indiana University-Purdue University Indianapolis (IUPUI) / Fluoridation of community water supplies for the purpose of preventing dental caries remains one of the top 10 public health interventions of the last century. However, exposure (ingestion) of greater than optimal amounts of fluoride from a variety of sources has led to an increase in the prevalence of dental fluorosis. We propose that dental fluorosis represents a complex condition caused by environmental and genetic factors. Purpose: To assess the role of genetics in the pathogenesis of dental fluorosis using genetically separate inbred strains of mice. Methods: Twelve genealogically disparate strains of mice were treated with 0 ppm, 25 ppm, and 50 ppm of fluoride in their drinking water. Each mouse was given weekly dental fluorosis evaluations. After 60 days of treatment, femurs were collected for fluoride analysis. Mandibular incisors were isolated for quantitative light induced fluorescence (QLF) studies and fluoride analysis. Digital and 35 mm images were taken of all mouse incisors in order to apply and compare the Dean's Index and the modified Thylstrup and Fejerskov Index (TFI), both indices of dental fluorosis. Skeletal radiographs were taken on the euthanized mice and later examined for extra skeletal calcifications and other gross bony deformities. Results: Differences in dental fluorosis susceptibility/resistance were identified between the strains, ranging from mild, moderate, to severe dental fluorosis. Furthermore, we found clustering of strains into distinct phenotypic groups. The A/J mouse strain was highly susceptible, with a rapid onset and severe development of dental fluorosis compared with the other strains tested. The 129P3/J mouse strain was least affected with negligible dental fluorosis. From the skeletal radiographs, no gross skeletal lesions or evidence of bone dysplasia were noted. Similar body burden of fluoride, as judged from analysis of mineralized tissues, was seen in all strains despite differences in their predispositions to develop dental fluorosis. Both the Dean's and TF indices are useful for classifying the stage or severity of fluorosis in mice, and there are advantages to the use of digital images over conventional 35 mm slide images. Both indices correlate well with the amount of fluoride exposure during amelogenesis; however, these indices are not promising indicators of fluoride burden during amelogenesis. Conclusions: QLF proved to be an innovative and useful tool for the quantification of dental fluorosis. Furthermore, these observations support the role of a genetic component in the pathogenesis of fluorosis.

The Role of TvTrxR in Drug Resistance and Characterization of TvRad51 in Homologous Recombination in Trichomonas vaginalis Abstract By Melissa Hopper University of the Pacific 2016 In recent years, prevalence of metronidazole-resistant cases of Trichomonas vaginalis has been on the rise. With nearly 10% of strains resistant to metronidazole, new treatments to combat this parasite have become a necessity. FDA-approved drug screens have identified the compound, auranofin, as an effective agent against similar protozoans. The mechanism of inhibition by auranofin has been found to proceed through inhibition of the thioredoxin-based anti-oxidant pathway, targeting the enzyme thioredoxin reductase (TrxR). In this study, auranofin was found to be an effective inhibitor of T. vaginalis TrxR activity. Auranofin was also found to be an effective inhibitor of several trichomonad strains in culture, exhibiting IC50 values comparable to metronidazole. These studies indicate that auranofin is a promising agent for treatment of trichomoniasis. Another aspect of T. vaginalis biology addressed in this study is the ability of T. vaginalis to carry out homologous recombination (HR), a process used to repair double-stranded breaks in DNA. The protein radiation sensitive protein 51 (Rad51) plays a crucial role in the process of HR in mitotic and meiotic recombination. In this study, experiments were carried out to elucidate the role of T. vaginalis Rad51 in homologous recombination. TvRad51 was found to exhibit nuclear localization and was capable of carrying out ATP hydrolysis. Rad51 was shown to be up-regulated at the protein level in T. vaginalis in response to treatment with DNA-damaging agents. In addition, TvRad51 was capable of binding the BRC repeat region of TvBRCA2. These results indicate that T. vaginalis upregulates expression of Rad51 protein in response to certain forms of DNA damage and TvRad51 may be capable of carrying out HR mediated by different binding partners.

Multidrug resistance (MDR) is a major obstacle of current chemotherapy. In this study, we investigated the effects ofpolyamines, acetylated polyamines and APAH, a polyamine deacetylase inhibitor, on LS180 cells and the derived MDR LS180 Ad-50 cells. L.ethal concentrations for 20% of the cells (LC20) for N8 -acetylspermidine (N8 - AcSPD) and SPD were 12.5 and 7 times greater for LS180 Ad-50 cells than for LS180 cells, respectively. However, there was no difference in LC20 levels for N1-AcSPD in LS180 and LS180 Ad-50 cells. Addition of 100 nM APAH to N8-AcSPD increased its LC20 to 17 foldgreater in MDR compared to non:·MDR cells. and resulted in increased cell growth at 5 μM N8-AcSPD. Furthermore, exposure to the LC20 concentrations of N8 -AcSPD for 48 hrs caused no significant change of intracellular Rhodamine (Rh) 123 concentrations. Adding 100 nM APAH to this N8 -AcSPD experiment led to a decrease of intracellular Rh123 concentration of 15-20% in both LS 180 and LS 180 Ad-50 cells. These Rh 123 concentrations further decreased in the presence of higher concentrations of APAH. Pretreatment of the cells with APAH did not affect these results. Kinetic studies suggest that APAH may be a non-competitive transport inhibitor of Rh123 transporter.

京都大学 / 0048 / 新制・課程博士 / 博士(理学) / 甲第18110号 / 理博第3988号 / 新制||理||1575(附属図書館) / 30968 / 京都大学大学院理学研究科生物科学専攻 / (主査)准教授 秋山 秋梅, 教授 沼田 英治, 教授 疋田 努 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

京都大学 / 0048 / 新制・課程博士 / 博士(医学) / 甲第19597号 / 医博第4104号 / 新制||医||1014(附属図書館) / 32633 / 京都大学大学院医学研究科医学専攻 / (主査)教授 松田 道行, 教授 野田 亮, 教授 山田 泰広 / 学位規則第4条第1項該当 / Doctor of Medical Science / Kyoto University / DFAM

No description available.

No description available.

No description available.

No description available.