No description available.

Breast cancer is the most prevalent cancer type among Canadian women. Breast cancers originate from the malignant transformation of mammary epithelial cells, which causes them to adopt an uncontrolled cell proliferation phenotype. My research suggests that the activity of specific ion channels (KV10.1, KCa3.1 and TRPM8) contribute to the proliferation of MCF-7 cells, a cell line commonly used to study breast cancer in vitro. Pharmacologically inhibiting the activities of KV10.1 or KCa3.1 channels decreased basal, but not estrogen-stimulated [3H]-thymidine incorporation, demonstrating that these channels contribute to MCF-7 cell proliferation. One way K+ channel activity is hypothesized to control cell proliferation is via regulation of membrane potential-dependent Ca2+ influx. Inhibition of KCa3.1 but not KV10.1 channel activity resulted in a membrane potential-dependent decrease in basal Ca2+ influx, suggesting that the way in which KCa3.1 channels contribute to cell proliferation is via regulating Ca2+ influx. In addition, my research also demonstrated that TRAM-34 increased or decreased cell proliferation depending on the concentration used and mitogenesis by TRAM-34 was blocked by estrogen receptor antagonists. TRAM-34 increased progesterone receptor mRNA expression, decreased estrogen receptor-alpha mRNA expression and reduced the binding of radiolabelled estrogen to estrogen receptor protein, in each case mimicking the effects of estrogen. Our finding that TRAM-34 is able to activate the estrogen receptor suggests a novel action of this supposedly specific K+ channel inhibitor and raises concerns of interpretation in its use. TRPM8 channels were also identified in MCF-7 cells, where they appeared to be important Ca2+ entry pathways. Inhibiting the activity of TRPM8 pharmacologically, as well as knocking down TRPM8 mRNA expression decreased cell proliferation, indicating that TRPM8 also contributed to MCF-7 cell proliferation. In conclusion, my research demonstrates that the activities of KV10.1, KCa3.1 and TRPM8 channels contribute to basal breast cancer cell proliferation. These findings suggest that the activity of specific ion channels may be potential targets for future therapeutic agents to treat breast cancer.

No description available.

No description available.

La Fibrose Kystique, causée par des mutations du canal CFTR, mène à la dysfonction du transport des fluides et des ions causant la déshydratation du liquide de surface des voies aériennes et ainsi une défaillance de la clairance mucocilliaire. Ce défaut entraine l’accumulation et l’épaississement du mucus au niveau des bronches qui devient alors un environnement idéal pour le développement d’infections chroniques et d’inflammation qui sont associées à la destruction progressive de l’épithélium chez les patients Fibrose Kystique. Même si leur rôle dans les processus lésionnels est très bien connu, l’impact de médiateurs inflammatoires sur la capacité de réparation ne l’est cependant pas. L’objectif de ma maitrise était donc d’étudier la régulation des mécanismes de réparation de l’épithélium bronchique sain et Fibrose Kystique par le facteur de nécrose tumoral (TNF)-alpha, une cytokine pro-inflammatoire cruciale dans l’initiation et la propagation de la réponse inflammatoire chez les patients FK. À l’aide d’un modèle de plaies mécaniques, nous avons montré que le TNF-alpha stimule la réparation de l’épithélium bronchique sain (NuLi-1) et Fibrose Kystique (CuFi-1). De façon surprenante, l’exposition chronique au TNF-alpha augmente cette stimulation tout comme le taux de migration cellulaire pendant la réparation. Cette augmentation de réparation semble être médiée par l’activation de la métalloprotéinase MMP-9, la relâche d’EGF par les cellules épithéliales et ainsi l’activation de la voie d’EGFR. De plus, l’activation de la réparation par le TNF-alpha semble aussi impliquer l’activation des canaux K+, dont nous avons démontré le rôle important dans la réparation. Contrairement à son effet sur la migration cellulaire et sur la réparation, le TNF-alpha diminue la prolifération cellulaire. En somme, en plus de son rôle dans les processus lésionnels, le TNF-alpha semble avoir un rôle complexe dans les processus de réparation puisqu’il stimule la migration et ralentit la prolifération cellulaire. / Cystic fibrosis (CF) pathology, caused by mutations of cftr gene, leads to ion and fluid transport dysfunction that results in mucus thickening and accumulation in the airways. This mucus accumulation promotes bacterial infection and airway inflammation associated with progressive airway epithelial damage in CF patients, unfortunately leading to respiratory failure. However, the effect of inflammatory products on the repair capacity of respiratory epithelia is unclear. Thus, the objective of my project was to study the regulation of normal and CF bronchial epithelial repair mechanisms by tumor necrosis factor-alpha (TNF)-alpha, a major component of inflammation initiation and propagation in CF. With a wound healing model, we observed that TNF-alpha stimulated the non-CF (NuLi-1) and CF (CuFi-1) bronchial wound healing rate. Surprisingly, chronic exposure to TNF-alpha enhanced this stimulation as well as the migration rate during repair. This wound healing rate stimulation by TNF-alpha seems to be due to metalloproteinase MMP-9 activation, EGF shedding by epithelial cells and subsequent EGFR transactivation. Furthermore, we recently reported a crucial relationship between the EGF response and K+ channel function, both controlling bronchial repair. We now show that TNF-alpha wound healing stimulation also implicated KvLQT1 and KATP currents activation. In contrast to its effect on cell migration, TNF-alpha downregulate cell proliferation. Thus, in addition to its recognized role in the inflammatory response leading to epithelial injury, TNF-a could exert complex actions on repair mechanisms of CF airway epithelia by upregulating cell migration while downregulating proliferation.

Schizophrenia is a devastating psychiatric disorder that affects approximately 1% of the population. The main treatments for schizophrenia are antipsychotic drugs that target dopamine receptors, yet the underlying biological mechanisms through which they alleviate the symptoms of schizophrenia remain ill defined. In this study, we used microarray analysis to profile the expression changes of thousands of genes simultaneously, following antipsychotic drug treatment of mice. Mice were treated chronically (28 days), or for a novel intermediate time-point (7 days), with one of three antipsychotic drugs: clozapine, haloperidol or olanzapine. The use of three drugs enabled us to discern antipsychotic-specific effects co-regulated by multiple drugs, rather than the side effects of individual compounds. Transcript profiling and validation by quantitative PCR of whole brain tissue revealed antipsychotic drug regulation of genes in diverse biological pathways, including: dopamine metabolism, neuropeptide and second-messenger signalling, neurogenesis, synaptic plasticity, cell adhesion, myelination, and voltage-gated ion channels. The regulation of voltage-gated channels by antipsychotic drugs has been suggested previously by electrophysiological studies, although thorough analysis has not been undertaken in vivo. Therefore, the second aim of this study was to characterise the regional mRNA and protein expression of two genes altered by multiple APDs, the voltage-gated potassium channel ??-subunit (Kcna1) and voltage-gated potassium channel interacting protein (Kchip3). Regional characterisation and expression analyses were carried out by immunohistochemistry, in situ hybridisation, and Western blot analysis of mouse brain regions of interest to schizophrenia and its treatment. Following 7-day haloperidol treatment we observed up-regulation of Kcna1 in the striatum and dentate gyrus, with increased protein in the striatum, hippocampus and midbrain; and down-regulation of Kchip3 in the striatum, with decreased protein in the cortex, hippocampus and midbrain. These studies implicate voltage-gated potassium channels in the antipsychotic drug regulation of midbrain dopaminergic neuronal activity, adult neurogenesis and/or striatothalamic GABAergic neuronal inhibition. These findings indicate that regulation of potassium channels may underlie some of the mechanisms of action of antipsychotic drugs, and that voltage-gated ion channels may provide alternative drug targets for the treatment of schizophrenia.

Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.

Thesis (Ph. D.)--Ohio State University, 2007. / Full text release at OhioLINK's ETD Center delayed at author's request

Thesis (Ph. D.)--University of Virginia, 2008. / Includes bibliographical references. Also available online through Digital Dissertations.

Thesis (Ph. D.)--University of Missouri-Columbia, 2007. / The entire dissertation/thesis text is included in the research.pdf file; the official abstract appears in the short.pdf file (which also appears in the research.pdf); a non-technical general description, or public abstract, appears in the public.pdf file. Vita. "August 2007" Includes bibliographical references.