Medicine and Health Sciences Commons^™

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 …

Regulation Of Toxin Synthesis By Clostridium Difficile, Charles Darkoh

Dissertations & Theses (Open Access)

Clostridium difficile is the leading definable cause of nosocomial diarrhea worldwide due to its virulence, multi-drug resistance, spore-forming ability, and environmental persistence. The incidence of C. difficile infection (CDI) has been increasing exponentially in the last decade. Virulent strains of C. difficile produce either toxin A and/or toxin B, which are essential for the pathogenesis of this bacterium. Current methods for diagnosing CDI are mostly qualitative tests that detect the bacterium, the toxins, or the toxin genes. These methods do not differentiate virulent C. difficile strains that produce active toxins from non-virulent strains that do not produce toxins or produce …

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 …

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 …

The Histone Deacetylase Inhibitor, Ms-275, Sensitizes Metastatic Osteosarcoma To Fasl-Induced Cell Death: A Role For C-Flip, Krithi R. Bindal

Dissertations & Theses (Open Access)

The purpose of this study was to determine the effects of the histone deacetylase inhibitor, MS-275, on the Fas signaling pathway and susceptibility of osteosarcoma (OS) to Fas ligand (FasL)-induced cell death. OS metastasizes almost exclusively to the lungs. We have shown that Fas expression in OS cells is inversely correlated with their metastatic potential. Fas⁺ cells are rapidly eliminated when they enter the lungs via interaction with FasL, which is constitutively expressed in the lungs. Fas^- OS cells escape this FasL-induced apoptosis and survive in the lung microenvironment. Moreover, upregulation of Fas in established OS lung metastases …

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 …