Medicine and Health Sciences Commons^™

Trim24-Regulated Estrogen Response Is Dependent On Specific Histone Modifications In Breast Cancer Cells, Teresa T. Yiu

Dissertations & Theses (Open Access)

In this dissertation, I discovered that function of TRIM24 as a co-activator

of ERα-mediated transcriptional activation is dependent on specific histone

modifications in tumorigenic human breast cancer-derived MCF7 cells. In the first

part, I proved that TRIM24-PHD finger domain, which recognizes unmethylated

histone H3 lysine K4 (H3K4me0), is critical for ERα-regulated transcription.

Therefore, when LSD1-mediated demethylation of H3K4 is inhibited, activation of

TRIM24-regulated ERα target genes is greatly impaired. Importantly, I

demonstrated that TRIM24 and LSD1 are cyclically recruited to estrogen

responsive elements (EREs) in a time-dependent manner upon estrogen

induction, and depletion of their expression exert corresponding time-dependent

effect …

Regulation Of The Heat Shock Response By Thiol-Reactive Compounds In The Yeast Saccharomyces Cerevisiae, Yanyu Wang

Dissertations & Theses (Open Access)

Cells govern their activities and modulate their interactions with the environment to achieve homeostasis. The heat shock response (HSR) is one of the most well studied fundamental cellular responses to environmental and physiological challenges, resulting in rapid synthesis of heat shock proteins (HSPs), which serve to protect cellular constituents from the deleterious effects of stress. In addition to its role in cytoprotection, the HSR also influences lifespan and is associated with a variety of human diseases including cancer, aging and neurodegenerative disorders. In most eukaryotes, the HSR is primarily mediated by the highly conserved transcription factor HSF1, which recognizes target …

Characterization Of A Novel Role For The Tousled- Like Kinase In Kinetochore Assembly And Function In Caenorhabditis Elegans, Jessica M. De Orbeta

Dissertations & Theses (Open Access)

Chromosome segregation is a critical step during cell division to avoid aneuploidy and promote proper organismal development. Correct sister chromatid positioning and separation during mitosis helps to achieve faithful transmission of genetic material to daughter cells. This prevents improper chromosome partitioning that can potentially result in extrachromosomal fragments, increasing the tumorigenic potential of the cells. The kinetochore is a protenaicious structure responsible for the initiation and orchestration of chromosome movement during mitosis. This highly conserved structure among eukaryotes is required for chromosome attachment to the mitotic spindle and failure to assemble the kinetochore results in aberrant chromosome segregation. Thus elucidating …

Genetic Analysis Of The Hippo Pathway In Mouse Liver, Li Lu

Dissertations & Theses (Open Access)

Cancer therapy and tumor treatment remain unsolved puzzles. Genetic screening for tumor suppressor genes in Drosophila revealed the Hippo-signaling pathway as a kinase cascade consisting of five core components. Disrupting the pathway by deleting the main component genes breaks the balance of cell proliferation and apoptosis and results in epithelial tissue tumorigenesis. The pathway is therefore believed to be a tumor suppressor pathway. However, a corresponding role in mammals is yet to be determined. Our lab began to investigate the tumor suppression function of the potent mammalian Hippo pathway by putting floxed alleles into the mouse genome flanking the functional-domain-expressing …

Biochemical Characterization Of Binding Partners Of Two Hsp70 Co-Chaperones In Saccharomyces Cerevisiae, Jacob Verghese

Dissertations & Theses (Open Access)

Cells are exposed to a variety of environmental and physiological changes including temperature, pH and nutrient availability. These changes cause stress to cells, which results in protein misfolding and altered cellular protein homeostasis. How proteins fold into their three-dimensional functional structure is a fundamental biological process with important relevance to human health. Misfolded and aggregated proteins are linked to multiple neurodegenerative diseases, cardiovascular disease and cystic fibrosis. To combat proteotoxic stress, cells deploy an array of molecular chaperones that assist in the repair or removal of misfolded proteins.

Hsp70, an evolutionarily conserved molecular chaperone, promotes protein folding and helps maintain …

A Study On The Function Of 14-3-3sigma In Regulating Cancer Energy Metabolism, Liem M. Phan, Liem M. Phan

Dissertations & Theses (Open Access)

Metabolic reprogramming has been shown to be a major cancer hallmark providing tumor cells with significant advantages for survival, proliferation, growth, metastasis and resistance against anti-cancer therapies. Glycolysis, glutaminolysis and mitochondrial biogenesis are among the most essential cancer metabolic alterations because these pathways provide cancer cells with not only energy but also crucial metabolites to support large-scale biosynthesis, rapid proliferation and tumorigenesis. In this study, we find that 14-3-3σ suppresses all these three metabolic processes by promoting the degradation of their main driver, c-Myc. In fact, 14-3-3s significantly enhances c-Myc poly-ubiquitination and subsequent degradation, reduces c-Myc transcriptional activity, and down-regulates …

Anti-Tumor Effects Of The Notch Pathway In Gastrointestinal Stromal Tumors, Amaury G. Dumont

Dissertations & Theses (Open Access)

Gastrointestinal Stromal Tumors (GIST) are sarcomas driven by gain-of-function mutations of KIT or PDGFRA. Although, the introduction of tyrosine kinase inhibitors has dramatically changed the history of this disease, evidences emerge that inhibition of KIT or PDGFRA are not sufficient to cure patients. The developmental pathway Notch has a critical role in the cell fate, regulating cell proliferation and differentiation. Dysregulation of Notch pathway has been implicated in a wide variety of cancers functioning as a tumor promoter or a tumor suppressor in a cell context dependent manner.

Given that Notch activation deregulates the morphogenesis of mesenchymal cells in …

Role Of Stat3 In Keratinocyte Stem Cells During Skin Tumorigenesis, Dharanija Rao

Dissertations & Theses (Open Access)

STATs play crucial roles in a wide variety of biological functions, including development, proliferation, differentiation, migration and in cancer development. In the present study, we examined the impact of Stat3 deletion or activation on behavior of keratinocytes, including keratinocyte stem cells (KSCs). Deletion of Stat3 specifically in the bulge region of the hair follicle using K15.CrePR1 X Stat3^fl/fl mice led to decreased tumor development by altering survival of bulge region KSCs. To further understand the role of KSCs in skin tumorigenesis, K5.Stat3C transgenic (Tg) mice which express a constitutively active/dimerized form of Stat3 called Stat3C via the bovine keratin …

Identification And Analysis Of A Novel Role For The Tousled-Like Kinase In Regulating Mitotic Spindle Dynamics, Jason R. Ford

Dissertations & Theses (Open Access)

Deregulation of kinase activity is one example of how cells become cancerous by evading evolutionary constraints. The Tousled kinase (Tsl) was initially identified in Arabidopsis thaliana as a developmentally important kinase. There are two mammalian orthologues of Tsl and one orthologue in C. elegans, TLK-1, which is essential for embryonic viability and germ cell development. Depletion of TLK-1 leads to embryonic arrest large, distended nuclei, and ultimately embryonic lethality. Prior to terminal arrest, TLK-1-depleted embryos undergo aberrant mitoses characterized by poor metaphase chromosome alignment, delayed mitotic progression, lagging chromosomes, and supernumerary centrosomes.

I discovered an unanticipated requirement for TLK-1 …

Platelets And Anti-Angiogenic Resistance In Ovarian Carcinoma, Justin N. Bottsford-Miller

Dissertations & Theses (Open Access)

Background: Resistance to targeted anti-angiogenic therapy is a growing clinical concern given the disappointing clinical impact of anti-angiogenic. Platelets represent a component of the tumor microenvironment that are implicated in metastasis and represent a significant reservoir of angiogenic regulators. Thrombocytosis has been shown to be caused by malignancy and associated with adverse clinical outcomes, however the causal connections between these associations remain to be identified.

Materials and Methods: Following IRB approval, patient data were collected on patients from four U.S. centers and platelet levels through and after therapy were considered as indicators of recurrence of disease. In vitro effects of …

Transcriptional Regulation Of Profilin Is Required For Drosophila Larval Wound Closure, Amanda Brock

Dissertations & Theses (Open Access)

Injury is an inevitable part of life, making wound healing essential for survival. In postembryonic skin, wound closure requires that epidermal cells recognize the presence of a gap and change their behavior to migrate across it. In Drosophila larvae, wound closure requires two signaling pathways (the Jun N-terminal kinase (JNK) pathway and the Pvr receptor tyrosine kinase signaling pathway) and regulation of the actin cytoskeleton. In this and other systems, it remains unclear how the signaling pathways that initiate wound closure connect to the actin regulators that help execute wound- induced cell migrations. Here we show that chickadee, which encodes …

Chronic Stress Promotes Tumor Growth Through Increased Bdnf Production And Neo-Innervation, Julie K. Allen

Dissertations & Theses (Open Access)

Background: Activation of the sympathetic nervous system (SNS) in response to chronic biobehavioral stress results in high levels of catecholamines and persistent activation of adrenergic signaling, which promotes tumor growth and progression. However it is unknown how catecholamine levels within the tumor exceed systemic levels in circulation. I hypothesized that neo-innervation of tumors is required for stress-mediated effects on tumor growth.

Results: First, I examined whether sympathetic nerves are present in human ovarian cancer samples as well as orthotopic ovarian cancer models. Immunohistochemical (IHC) staining for neurofilament revealed that catecholaminergic neurons are present within tumor tissue. In order to determine …

Role Of Trp Channels In Mediating The Calcium Signaling Response Of Brain Endothelial Cells To Mechanical Stretch, Jonathan Berrout

Dissertations & Theses (Open Access)

Traumatic brain injury (TBI) often results in disruption of the blood brain barrier (BBB), which is an integral component to maintaining the central nervous system homeostasis. Recently cytosolic calcium levels ([Ca²⁺]i), observed to elevate following TBI, have been shown to influence endothelial barrier integrity. However, the mechanism by which TBI-induced calcium signaling alters the endothelial barrier remains unknown. In the present study, an in vitro BBB model was utilized to address this issue. Exposure of cells to biaxial mechanical stretch, in the range expected for TBI, resulted in a rapid cytosolic calcium increase. Modulation of intracellular and extracellular …

Elucidating The Igfbp2 Signaling Pathway In Glioma Development And Progression, Kristen M. Holmes

Dissertations & Theses (Open Access)

Diffuse gliomas are highly lethal central nervous system malignancies which, unfortunately, are the most common primary brain tumor and also the least responsive to the very few therapeutic modalities currently available to treat them. IGFBP2 is a newly recognized oncogene that is operative in multiple cancer types, including glioma, and shows promise for a targeted therapeutic approach. Elevated IGFBP2 expression is present in high-grade glioma and correlates with poor survival. We have previously demonstrated that IGFBP2 induces glioma development and progression in a spontaneous glioma mouse model, which highlighted its significance and potential for future therapy. However, we did not …

Identification And Characterization Of Distinct Populations Of Clonogenic Bone Marrow Stromal Cells Capable Of Transferring The Hematopoietic Microenvironment In Vivo And Supporting Lt-Hscs In Vitro, Colby Suire

Dissertations & Theses (Open Access)

Bone marrow (BM) stromal cells are ascribed two key functions, 1) stem cells for non-hematopoietic tissues (MSC) and 2) as components of the hematopoietic stem cell niche. Current approaches studying the stromal cell system in the mouse are complicated by the low yield of clonogenic progenitors (CFU-F). Given the perivascular location of MSC in BM, we developed an alternative methodology to isolate MSC from mBM. An intact ‘plug’ of bone marrow is expelled from bones and enzymatically disaggregated to yield a single cell suspension. The recovery of CFU-F (1917.95+199) reproducibly exceeds that obtained using the standard BM flushing technique (14.32+1.9) …

Regulation Of Protein Degradation In The Heart By Amp-Activated Protein Kinase, Kedryn K. Baskin, Kedryn K. Baskin

Dissertations & Theses (Open Access)

The degradation of proteins by the ubiquitin proteasome system is essential for cellular homeostasis in the heart. An important regulator of metabolic homeostasis is AMP-activated protein kinase (AMPK). During nutrient deprivation, AMPK is activated and intracellular proteolysis is enhanced through the ubiquitin proteasome system (UPS). Whether AMPK plays a role in protein degradation through the UPS in the heart is not known. Here I present data in support of the hypothesis that AMPK transcriptionally regulates key players in the UPS, which, under extreme conditions can be detrimental to the heart. The ubiquitin ligases MAFbx /Atrogin-1 and MuRF1, key regulators of …

Microrna Regulation Of Prostate Cancer Stem/Progenitor Cells And Prostate Cancer Development, Can Liu

Dissertations & Theses (Open Access)

Most human tumors contain a population of cells with stem cell properties, called cancer stem cells (CSCs), which are believed to be responsible for tumor establishment, metastasis, and resistance to clinical therapy. It’s crucial to understand the regulatory mechanisms unique to CSCs, so that we may design CSC-specific therapeutics. Recent discoveries of microRNA (miRNA) have provided a new avenue in understanding the regulatory mechanisms of cancer. However, how miRNAs may regulate CSCs is still poorly understood. Here, we present miRNA expression profiling in six populations of prostate cancer (PCa) stem/progenitor cells that possess distinct tumorigenic properties. Six miRNAs were identified …

Increased Geranylgeranylated K-Ras Contributes To Antineoplastic Effects Of Farnesyltransferase Inhibitors., Mandy A. Hall

Dissertations & Theses (Open Access)

The Ras family of small GTPases (N-, H-, and K-Ras) is a group of important signaling mediators. Ras is frequently activated in some cancers, while others maintain low level activity to achieve optimal cell growth. In cells with endogenously low levels of active Ras, increasing Ras signaling through the ERK and p38 MAPK pathways can cause growth arrest or cell death. Ras requires prenylation – the addition of a 15-carbon (farnesyl) or 20-carbon (geranylgeranyl) group – to keep the protein anchored into membranes for effective signaling. N- and K-Ras can be alternatively geranylgeranylated (GG’d) if farnesylation is inhibited but are …

Regulation Of Protein Degradation In The Heart By Amp-Activated Protein Kinase, Kedryn K. Baskin

Dissertations & Theses (Open Access)

The degradation of proteins by the ubiquitin proteasome system is essential for cellular homeostasis in the heart. An important regulator of metabolic homeostasis is AMP-activated protein kinase (AMPK). During nutrient deprivation, AMPK is activated and intracellular proteolysis is enhanced through the ubiquitin proteasome system (UPS). Whether AMPK plays a role in protein degradation through the UPS in the heart is not known. Here I present data in support of the hypothesis that AMPK transcriptionally regulates key players in the UPS, which, under extreme conditions can be detrimental to the heart. The ubiquitin ligases MAFbx /Atrogin-1 and MuRF1, key regulators of …

Induced-Pluripotent Stem-Derived Neuronal Progenitor Cells As A Novel Treatment For Neurodegenerative Diseases, Dennisse A. Gonzalez-Romero

Dissertations & Theses (Open Access)

Cellular therapies, as neuronal progenitor (NP) cells grafting, are promising therapies for patients affected with neurodegenerative diseases like Creutzfeldt-Jakob Disease (CJD). At this time there is no effective treatment or cure for CJD. The disease is inevitably fatal and affected people usually die within months of the appearance of the first clinical symptoms. Compelling evidence indicate that the hallmark event in the disease is the conversion of the normal prion protein (termed PrP^C) into the disease-associated, misfolded form (called PrP^Sc). Thus, a reasonable therapeutic target would be to prevent PrP misfolding and prion replication. This strategy …