Thesis (Ph.D.)--University of Florida, 2005. / Typescript. Title from title page of source document. Document formatted into pages; contains 162 pages. Includes Vita. Includes bibliographical references.

The dissemination of tumor cells to distant organs i.e. metastasis is an exceedingly complex process leading to 90% of all cancer deaths. Despite being so clinically important, little is known about this process that requires tumor cells to leave the primary tumor site, intravasate and transport through the blood stream, extravasate and colonize at secondary sites leading to distant metastases. Survivin, a member of the IAP (Inhibitor of Apoptosis) family with known functions in apoptosis and mitosis, is highly expressed in aggressive tumors and is associated with poor prognosis and adverse clinical outcome. But the mechanistic role of survivin in metastatic dissemination has not been investigated. In this study, we demonstrate an important and novel role of survivin in activating a broad gene expression program in tumor cells. Of particular importance is the upregulation of a distinct class of cell adhesion molecules, particularly fibronectin. This IAP mediated gene regulation requires synergistic intermolecular cooperation between survivin and its related cofactor molecule, XIAP that results in activation of NF-κB dependent fibronectin gene expression. The binding of fibronectin with its cognate cell surface receptors initiates outside–in signaling leading to the autocrine and paracrine activation of cell motility kinases, FAK and Src, in turn leading to enhanced tumor invasion and metastasis. The importance of survivin and XIAP in the process of metastasis has also been demonstrated in vivousing intrasplenic injections in mouse models. Overall this study is the first to place survivin upstream of transcriptional activation of gene expression particularly fibronectin. In addition, it also demonstrates the importance of survivin-XIAP complex in mediating NF-κB activation which in turn switches on the expression of various target genes involved in tumor metastasis. Hence this study dissects the upstream and downstream requirements of survivin- XIAP complex mediated tumor dissemination and metastasis. Significance of this Study The hallmark of end-stage cancer is metastasis, an incurable condition almost invariably associated with death from disease. Despite a better understanding of the metastatic process, and the identification of key gene expression requirements of this pathway, the development of anti-metastatic therapies has lagged behind, with no viable options being currently offered in the clinical setting. Our findings that Inhibitor of Apoptosis (IAP) proteins functions as metastasis-promoting genes independently of cell survival, but through activation of cell motility could have important ramifications for the broader application of IAP antagonists currently in early clinical trials, as novel anti-metastatic therapies.

Cell adhesion to the extracellular matrix (ECM) provides tissue structure and integrity as well as triggers signals that regulate complex biological processes such as cell cycle progression and tissue-specific cell differentiation. Hence, cell adhesion is critical to numerous physiological and pathological processes, including embryonic development, cancer metastasis, and wound healing, as well as biotechnological applications, such as host responses to implanted devices and integration of tissue-engineered constructs. During the adhesion process, integrin surface receptors bind ECM proteins, cluster, and associate with the actin cytoskeleton. Subsequent strengthening of the integrin/actin cytoskeleton interaction occurs via complexes of proteins known as focal adhesions. Due to the close association between biochemical and biophysical processes within adhesion complexes, mechanical analyses can provide important new insights into structure/function relationships involved in regulating the adhesion process. The objective of this project was to investigate the role of the protein tyrosine kinase FAK in cell adhesion strengthening. Our central hypothesis was that FAK regulates adhesion strengthening by modulating interactions between integrins and FA structural components. Using a novel combination of genetically engineered cells to control the interactions of FAK, a spinning disk adhesion assay with micropatterned substrates to obtain reproducible and sensitive measurements of adhesion strength, and quantitative biochemical assays for analyzing changes in adhesive complexes, we demonstrate that FAK modulates adhesion strengthening via two distinct mechanisms: (1) FAK expression results in elevated integrin activation leading to regulation of strengthening rate and (2) FAK regulates steady-state adhesion strength via vinculin recruitment to focal adhesions. We also show that the autophosphorylation and catalytic sites of FAK are critical to this regulation of adhesion strengthening. This work is significant because it both identifies functional mechanisms of FAK and provides the first evidence that focal adhesion signaling regulates the adhesion strengthening process. Furthermore, this research demonstrates that the dependency of migration on adhesion strength is highly complex and establishes a need for adhesion strengthening metrics in analyzing the functional mechanisms of molecules within adhesion complexes.

Cardiovascular disease is the main cause of death in the United States. Many of these conditions require the grafting or bypassing of compromised blood vessels. To this effect, biological vascular grafts (autografts and allografts) are the first line of action. However, when the patient lacks vasculature suitable for grafting use, several synthetic grafting options are available. The search for an inert biomaterial for vascular grafts has proven to be unsuccessful. This makes the interaction taking place on the blood-biomaterial interface critical for the success of the grafts. This thesis introduces a new bio-inspired approach to tackle the mechanical and biological challenges of vascular material design. The hypothesis of this research is that recombinant fibronectin protein can be stably incorporated onto elastin-mimetic polymers to increase endothelialization. Recombinant elastin, designed to recreate the mechanical properties of natural elastin as a candidate material for vascular graft fabrication, was used as a model surface. Recombinant fibronectin-functionalized elastin-mimetic polymer displayed significant improvement in cell adhesion. Quantification of surface bound recombinant fibronectin verified the concentration dependence of this cell adhesive behavior. Modified elastin-mimetic polymer also demonstrated an enhanced ability to support endothelial cell proliferation. Furthermore, the stability of recombinant fibronectin-modified polymers was assessed. These studies provide the foundation for fabricating elastin-mimetic vascular grafts with improved endothelialization and subsequent biological performance.

Thesis (Ph. D.)--University of Alabama at Birmingham, 2008. / Title from first page of PDF file (viewed June 6, 2008). Includes bibliographical references.

Indiana University-Purdue University Indianapolis (IUPUI) / The impact of tobacco smoking on human health is well documented. The influence of smoking on tooth loss and cardiovascular diseases was investigated in the current study via both epidemiology and in vitro studies. From analyzing the 2006 Behavioral Risk Factor Surveillance System (2006 BRFSS) database, we confirmed that smoking was significantly associated with the number of teeth lost in a dose-dependent manner and smoking cessation reduced the risk when compared to those subjects continuing to smoke. In addition, the virulence factors related to caries were compared between Streptococcus mutans and Streptococcus gordonii in response to cigarette smoking condensate (CSC) treatment. We observed that S. gordonii was more susceptible to CSC treatment than S. mutans. CSC significantly enhanced S. mutans sucrose-dependent and independent adherence. Western blot assays revealed that several bacterial surface proteins including glucosyltransferase (GTF), glucan-binding proteins and antigen I/II, were significantly upregulated for the treated S. mutans. These findings suggested that the oral environment with CSC may favor a cariogenic dominant composition, which may increase the risk for smokers to develop caries. We also found that smoking and oral health status modified each other and synergistically increased the risk of CVD and this joint effect was more pronounced among the youngest age group using the 2006 BRFSS database. To further understand the joint effect, we conducted an in vitro study to investigate bacterial attachment to fibronectin and endothelial cells in response to smoking condensate treatment. Our study clearly demonstrated CSC significantly enhanced S. mutans attachment to both soluble and immobilized fibronectin as well as endothelial cells. Furthermore, our data suggested that bacteria possessed several adhesins that bound to host tissues and endothelial cells also had multiple receptors for bacterial attachment. Among these adhesins, antigen I/II seemed essential for bacterial attachment to endothelial cells without CSC. The knowledge of bacterial attachment to host tissues in the presence of CSC may help in developing different preventive or therapeutic strategies against attachment and colonization of the host by S. mutans.