Medicine and Health Sciences Commons^™

Uncovering Molecular Targets To Overcome Immunosuppression In Non-Small Cell Lung Cancer With Acquired Tki Resistance, Sonia A. Patel

Dissertations & Theses (Open Access)

Non-small cell lung cancer (NSCLC) remains the leading cause of cancer-related deaths worldwide. Targeted therapeutic agents, such as epidermal-like growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) or monoclonal antibodies targeting vascular endothelial growth factor (VEGF/R), can effectively inhibit upregulated signaling pathways driving tumorigenesis in NSCLC and many other cancers. Unfortunately, however, resistance to such targeted therapies inevitably arise in most patients and can occur through a variety of resistance mechanisms including genomic alterations and upregulation of bypass pathways. Additionally, patients who have acquired resistance to these targeted agents typically have tumors characterized by an immunosuppressive tumor microenvironment and thus …

Med12 Is A Critical Regulator Of Neural Crest Lineage And Nervous System Myelination, Fatma Betul Aksoy Yasar

Dissertations & Theses (Open Access)

The Mediator complex (MED) is a multi-subunit protein complex integral to the eukaryotic transcription machinery. MED12 is a Cdk8- regulatory kinase module subunit directly implicated in human disease and is genetically altered in neurological disease and cancer. Numerous attempts at generating an in vivo system to study the role of Med12 failed due to embryonic lethality associated with germline or developmental disruption of Med12 gene. To understand the cellular and molecular processes associated with its role in disease, we generated multiple mouse models with targeted depletion of MED12 in distinct cellular lineages. Our genetically engineered models with induced and conditional …

Risk-Factor Induced Changes In The Breast Microenvironment Facilitate Inflammatory Breast Cancer Progression And Lymphovascular Invasion, Wintana Balema, Wintana Balema

Dissertations & Theses (Open Access)

Inflammatory breast cancer (IBC) is a rapidly progressing, rare and highly lethal form of breast cancer. IBC is a clinical diagnosis, requiring >1/3 involvement on the affected breast and/or skin by erythema, and disease onset of < 6 months. The clinical symptoms of IBC vary in severity and presentation, these include redness, warmth, skin thickening and bruised or pink/purple discoloration appearance and skin changes such as peau d’orange. These skin symptoms are not attributed to inflammation, rather IBC is characterized by florid lymphovascular tumor emboli clogging dermal lymphatics. This leads to “classic” symptoms of breast swelling and skin edema or discoloration. To date, unique genomic drivers which differentiate IBC from non-IBC invasive breast cancers have not been identified highlighting a role for the microenvironment. Several epidemiological studies have unveiled subtype-specific risk factors associated with IBC that are known to alter the microenvironment. Obesity is an established risk factor for all subtypes of IBC. Never-breastfeeding increases risk for developing the most aggressive, triple-negative IBC. Further, never breastfeeding is associated with later clinical stage and worse outcomes. We worked to model these overlapping risk factors to understand microenvironment changes that may lead to the lymphatic change’s indicative of IBC.

First, we investigated the association of a “classic” triad of clinical IBC signs with overall survival among patients to demonstrate the most overt clinical findings of lymphatic involvement were impacting prognosis. We evaluated a triad of IBC signs, including swollen involved breast, nipple change, and diffuse skin change, using breast medical photographs from patients enrolled on a prospective IBC registry. We reported that the …

Ankyrin Dependent Mitochondrial Function And Bioenergetics In The Heart, Janani Subramaniam, Janani Subramaniam

Dissertations & Theses (Open Access)

ANK2 mutations in patients are associated with numerous arrhythmias, cardiomyopathies, and other heart defects. In the heart, AnkB, the protein encoded by ANK2, clusters relevant ion channels and cell adhesion molecules in several important domains; however, its role at Mitochondria Associated ER/SR Membranes (MAMs) has yet to be investigated. MAMs are crucial to mitochondrial function and metabolism and are signaling hubs implicated in various cardiac pathologies. Among several functions, these sites mediate the direct transfer of calcium from the ER/SR to the mitochondria to modulate ATP synthesis. Given that mitochondrial function and energy production are paramount to cardiovascular heath, …

Yap And Taz Are Required For Neural Crest-Derived Cardiovascular Development, Shannon Erhardt

Dissertations & Theses (Open Access)

Congenital heart defects (CHDs) are the most common human birth defect, occurring in ~1/100 newborns, and are a leading cause of early infant death. Cardiac neural crest cells (NCCs) are a migratory and multipotent cell population known to aid in the development of the cardiac outflow tract (OFT), valves, and interventricular septum, during embryogenesis. Yap and Taz are downstream effectors of the fundamental Hippo signaling pathway and are vital for proper organ and tissue development, yet their role in neural crest (NC)-derived heart formation is still largely unknown. We generated Yap and Taz conditional knockout (CKO) mice using a Cre-lox …

Investigation Of Genomic Instability Induced By G-Quadruplexes In The Absence Of Functional Topoisomerase 1 In Yeast, Alexandra Berroyer

Dissertations & Theses (Open Access)

Topoisomerase 1 (Top1) is an enzyme that removes transcriptionally generated negative supercoils by binding and nicking DNA. Since transcription of guanine-rich DNA leads to the formation of G-quadruplex (G4) structures, Top1’s function likely suppresses G4-formation. In support of this, Top1 significantly reduces co-transcriptional G4 DNA-associated genomic instability at a model G4-motif in Saccharomyces cerevisiae. However, whether Top1 suppresses G4-formation on a genome-wide scale in yeast remains unexplored. Therefore, I aimed to uncover if deletion of Top1 enhances genome-wide G4-formation in S. cerevisiae. As an approach to quantify global G4-formation, I expressed the G4-specific antibody BG4 from a yeast …

Modulation Of Kras Structure And Dynamics By Kras Ubiquitination And Membrane Depolarization, Vinay Nair

Dissertations & Theses (Open Access)

KRAS, a 21 kDa small GTPase protein, functions as a molecular switch playing a key role in regulating cell proliferation. Dysregulation of KRAS signaling by oncogenic mutations leads to uncontrolled cell proliferation, a hallmark of cancer cells. Attempts to therapeutically target oncogenic KRAS have led to limited success resulting in a need to identify new mechanisms to targeting KRAS. The interaction of KRAS with its regulators, effectors, and the membrane present one such avenue. In this study, we investigated how post-translational covalent and environmental modifications could modulate these interactions of KRAS. Using computational molecular dynamics simulations, nuclear magnetic resonance spectroscopy …

Computational Approaches To Understand Chemoresistance & Tumor Evolution Using Longitudinal Clinical Data And Lineage Tracing, Sahil Seth

Dissertations & Theses (Open Access)

Tumors are highly heterogeneous and dynamic, continually adapting and evolving in response to their microenvironment as well as external perturbations. Multi-region (spatial) and single cell sequencing has enabled us to anatomize the heterogeneity further and provide evidence of its association with chemo and drug resistance. To investigate this further we took two different approaches to understand the chemo-resistance, and functional heterogeneity in Triple negative breast cancer (TNBC) and Pancreatic ductal carcinoma in situ (PDAC) from an evolutionary perspective.

The first approach was to leverage tumor profiling from an ongoing randomized clinical trial in triple-negative breast cancer (ARTEMIS) to assess mechanisms …

Mutant Kras Alters Extracellular Vesicle Microrna Sorting In Pancreatic Cystic Neoplasms, Rachel L. Dittmar

Dissertations & Theses (Open Access)

Pancreatic ductal adenocarcinoma (PDAC) is among the deadliest cancers by organ site with a 5-year survival rate of just 10.8%. This is largely because most patients do not experience symptoms until the disease has already metastasized. The best hope to cure PDAC is surgery, which can only be done with a curative intent at an early stage when the disease is localized. There are no reliable circulating, body-fluid-based biomarkers to detect early stage PDAC or its precursor lesions in a timely manner for effective surgical intervention. When potential PDAC precursor lesions, such as mucinous pancreatic cysts are found, there are …

The Importance Of Dna Repair Capacity To (And A Model To Predict) Cell Radiosensitivity To Ions, David B. Flint, David B. Flint

Dissertations & Theses (Open Access)

Radiation therapy with ions has a number of advantages over conventional radiation therapy with photons, including favorable depth-dose distributions, greater relative biological effectiveness (RBE) and a lesser dependence on a number of biological factors known to affect radiosensitivity to photons, including DNA repair capacity. Thus, it is expected that an additional benefit of using ions is that they mitigate the great heterogeneities in treatment responses commonly observed in photon therapies.

However, by analyzing the cell survival of human cancer cell lines exposed to clinically relevant photon, proton, and carbon ion beams, we show there is not significantly less relative variability …

Unveiling Global Roles Of G-Quadruplexes And G4-22 In Human Genetics, Ruth Barros De Paula

Dissertations & Theses (Open Access)

G-quadruplexes are non-B DNA structures formed by four or more runs of repeated guanines that confer unique features to living organism’s genomes. These sequences are enriched in regulatory regions, such as promoters and 5’ UTRs, and have distinct regulatory roles in both health and disease states. Even though previous studies showed the impact of G4 in gene expression, none of them summarized the location-specific effect of G4. Also, there is no broad understanding about the most common G4 repeat in the human genome, named here as G4-22, and how it links to the evolution of mammals and their biology. In …

Biases And Blind-Spots In Genome-Wide Crispr-Cas9 Knockout Screens, Merve Dede

Dissertations & Theses (Open Access)

Adaptation of the bacterial CRISPR-Cas9 system to mammalian cells revolutionized the field of functional genomics, enabling genome-scale genetic perturbations to study essential genes, whose loss of function results in a severe fitness defect. There are two types of essential genes in a cell. Core essential genes are absolutely required for growth and proliferation in every cell type. On the other hand, context-dependent essential genes become essential in an environmental or genetic context. The concept of context-dependent gene essentiality is particularly important in cancer, since killing cancer cells selectively without harming surrounding healthy tissue remains a major challenge. The toxicity of …

Molecular Drivers Of Bladder Cancer Motility, Bryan Wehrenberg

Dissertations & Theses (Open Access)

Bladder cancer (BC) progression is measured by the degree of tumor cell invasion into the bladder wall and dissemination to distant sites. The study of BC cell motility will both enable development of anti-invasion therapeutics to limit progression of early-stage disease and improve our understanding of the metastatic process which drives patient mortality in BC. BCs display a great deal of intertumoral heterogeneity, and can be divided into basal and luminal subtypes, which are biologically and clinically distinct entities. Here, I examine the invasion phenotypes of BC as a function of both subtype and epithelial to mesenchymal transition (EMT) status. …

Sine Oculis Homeobox Homolog 1 (Six1) Plays A Critical Role In The Progression Of Pulmonary Fibrosis., Cory Wilson

Dissertations & Theses (Open Access)

Idiopathic pulmonary fibrosis (IPF) is the most common idiopathic interstitial pneumonia with a median survival time of 2-4 years after diagnosis. The alarming mortality rate is due to the lack of effective treatments. IPF is a chronic disease that is characterized by alveolar destruction due to increasing extracellular matrix deposition that leads to poor lung compliance, impaired gas exchange, and ultimately respiratory failure. Repetitive alveolar epithelial injury is a central process to the underlying pathology with injury to the type II alveolar epithelial cells (AT2) specifically being a key player in the pathogenesis of IPF. Recent studies have shown that …

Fibroblast Heterogeneity In Pancreatic Cancer Immunity, Josephine Darpolor

Dissertations & Theses (Open Access)

Fibroblasts are a unique cell type defined by their mesenchymal phenotype and exclusion from epithelial, immune, and endothelial cell subsets. Although well studied in wound healing, cancer associated fibroblasts (CAFs) are incredibly heterogeneous, leading to contradictions as to the roles CAFs play in the tumor microenvironment (TME). CAFs were thought to be a barrier to treatment of pancreatic ductal adenocarcinoma (PDAC). However, general stromal targeting strategies have largely failed in the clinic likely due to the heterogeneity of CAFs in the TME. Therefore, our groups and others have worked to unravel the heterogeneity of CAFs in PDAC. In the works …

Impact Of Epa And Dha Supplementation And 15-Lox-1 Expression On Colitis And Colitis-Associated Colorectal Cancer, Jonathan Jaoude

Dissertations & Theses (Open Access)

Inflammatory bowel disease (IBD) patients not only suffer from colitis but also from increased morbidity and mortality of colitis-associated colorectal cancer (CAC). The enzyme 15-lipoxygenase-1 (15-LOX-1) is crucial to converting omega-3 fatty acid derivatives eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) to resolvins, potent anti-inflammatory products. 15-LOX-1 effects on the conversion of EPA and DHA to resolvins that subsequently exert anti-inflammatory and anti-tumorigenic effects have received little attention. To address this knowledge gap, we hypothesize that 15-LOX-1 expression in colonic epithelial cells is essential for resolvin biosynthesis from EPA and DHA to modulate immunophenotype, limit inflammation, promote resolution, and help …

Uncovering The Zeb1 Interactome To Identify Novel Regulators Of Metastatic Non-Small Cell Lung Cancer, Roxsan Manshouri

Dissertations & Theses (Open Access)

Non-small cell lung cancer (NSCLC) is the leading cause of cancer-related death in the United States, due in part to the robust affinity of lung cancer cells to metastasize. Understanding the processes that contribute to metastasis provides promise for the discovery of novel therapeutic targets. Epithelial-tomesenchymal transition (EMT) is a proposed model for the initiation of metastasis. During EMT cell adhesion and polarity is reduced, allowing epithelial cancer cells to dissociate from the primary tumor and invade distant organs. The transcription factor zinc finger E-box-binding homeobox 1 (ZEB1) has been reported to uniquely correlate with NSCLC disease progression and to …

The Role Of Membrane Domains In Protein And Lipid Sorting During Endocytic Traffic, Blanca B. Diaz-Rohrer

Dissertations & Theses (Open Access)

The lipid and protein composition of the plasma membrane (PM) must be tightly controlled to maintain cellular functionality, despite constant, rapid endocytosis. Because de novo synthesis of proteins and lipids is energetically costly, the cell depends on active recycling to return endocytosed membrane components back to the PM. For most proteins, the mechanisms and pathways of their PM retention remain unknown. The work presented here shows that association with ordered membrane microdomains is fully sufficient for PM recycling and that abrogation of raft partitioning leads to their degradation in lysosomes. These findings support a model wherein ordered membrane domains mediate …

Investigating The Role Of Cd109 In Pancreatic Ductal Adenocarcinoma, Mennatallah Shaheen

Dissertations & Theses (Open Access)

Pancreatic Ductal Adenocarcinoma (PDAC) is the 3rd leading cause of cancer death in the US. We performed loss of function genomic screening on a cohort of four patient derived PDAC cell populations and our data shows a cell surface receptor CD109 to be a common vulnerability, the biologic role of which in PDAC is yet unstudied and largely unknown. We hypothesized that CD109 expression provides PDAC cells with a survival advantage, and promotes cancer progression through activation of downstream signaling. We believe therefore that targeting CD109 could improve PDAC patients’ survival. Here we report that CD109 plays a role in …

Role Of C-Met And Egfr In Acquired Resistance To Parp Inhibitors In Triple-Negative Breast Cancer, Clinton Yam

Dissertations & Theses (Open Access)

Triple-negative breast cancer is associated with a poor prognosis and treatment options are limited. The Poly (ADP-ribose) polymerase (PARP) inhibitors, olaparib and talazoparib, were recently approved for metastatic breast cancer (including triple-negative breast cancer) in patients with a germline BRCA1/2 mutation. Despite impressive response rates of ~60%, the prolongation in median progression-free survival with PARP inhibitors is modest, suggesting the emergence of resistance. We previously demonstrated that c-MET contributes to intrinsic resistance to PARP inhibitors in triple-negative breast cancer. However, whether c-MET plays a role in acquired resistance to PARP inhibitors in triple-negative breast cancer remains unclear. Here, we show …

Cross-Presentation Is A Source Of Tumor Antigens For Multiple Myeloma Immunotherapy, Alexander A. Perakis

Dissertations & Theses (Open Access)

Cross-presentation is an essential bridge between the innate and adaptive arms of the immune system where antigen presenting cells (APCs) prime cytotoxic T cell responses. We have recently identified cross-presentation as a mechanism by which solid tumors present exogenous antigens. We therefore hypothesized that multiple myeloma would be capable of cross-presentation as these cells are derived from B cells, known APCs. We explored the capacity of multiple myeloma to cross-present PR1, a human leukocyte antigen (HLA)-A2 nonameric peptide that is derived from neutrophil elastase (NE) and proteinase 3 (P3), and the ability to treat multiple myeloma using PR1-targeting immunotherapies. Here …

The Role Of Tumor Suppressor Dear1 In The Acquisition Of Mammary Stem/Progenitor Cell Properties, Uyen Le

Dissertations & Theses (Open Access)

Breast cancer is the most commonly diagnosed cancer in women in America. Ductal carcinoma in situ (DCIS), one of the earliest pre-invasive forms of invasive ductal carcinoma (IDC), has a 30-50% risk of progressing to IDC. Understanding the mechanisms regulating progression from DCIS to IDC would help identify biomarkers to stratify patients at higher risk of progression or metastasis. Cumulative literature suggests the earliest phase of dissemination from the primary tumor is driven by the epithelial-mesenchymal transition (EMT) program. DEAR1 is a tumor suppressor gene which is mutated, undergoes loss of heterozygosity in breast cancer, and is downregulated in DCIS …

The Role Of Perivascular Fibrosis In Post-Stroke Glymphatic Impairment And Cerebral Amyloid Angiopathy, Matthew D. Howe

Dissertations & Theses (Open Access)

In healthy brain tissue, toxic amyloid-β (Aβ) proteins are transported by the pulsatile flow of cerebrospinal fluid (CSF) along perivascular drainage pathways. Ischemic stroke may disrupt this process, leading to a perivascular build-up of Aβ, termed cerebral amyloid angiopathy (CAA). I hypothesize that an abnormal pattern of extracellular matrix deposition within the vascular basement membrane, termed fibrosis, impairs Aβ drainage from the aged brain after stroke. I further hypothesize that inhibition of astrocytic transforming growth factor-β (TGF-β) signaling can reverse these phenotypes. Finally, I also hypothesize that serum biomarkers of perivascular fibrosis can be used to diagnose CAA following intracerebral …

Microrna Functions In Uv-Induced Cutaneous Squamous Cell Carcinoma, Tran Nguyen

Dissertations & Theses (Open Access)

Cutaneous squamous cell carcinoma (cuSCC) is the second most common skin cancer, for which long term UV exposure and chronic wounding are the dominant risk factors. Despite these clinically established connections, little is understood about the early molecular response of human skin to UV exposure and its connection to acute wounding and cuSCC. Thus, our goal is to find common and specific signatures driven by UV-exposure and wounding as a means of developing new approaches for treating and preventing cuSCC.

Here, we perform integrated analyses of RNA-seq and miR-seq on 3 datasets: (1) UV-unexposed and acute UV-exposed human skin, (2) …

The Role Of Merlin And Apicobasal Polarity In Endometrial Development And Homeostasis, Erin Lopez

Dissertations & Theses (Open Access)

Apicobasal polarity and cell adhesion are necessary for the proper formation and organization of epithelial tissues. Merlin couples cell polarity and adhesion through correct localization of the polarity protein Par3 and maturation of apical junctions. Merlin and Par3 are necessary for the development and homeostasis of highly regenerative tissues like the epidermis. The continual repopulation of the endometrium after each menstrual cycle requires a constant reorganization of cell polarity and adhesion. The endometrium consists of a luminal epithelium that postnatally gives rise to the distinct glandular epithelium. Endometrial glands are necessary to secrete nutrients for the pre-implantation embryo. In addition, …

Insights Into The Therapeutic Potential Of Salt Inducible Kinase 1: A Novel Mechanism Of Metabolic Control, Randi Fitzgibbon

Dissertations & Theses (Open Access)

Salt inducible kinase 1 (SIK1) has been considered a stress-inducible kinase since it was first cloned in 1999. Continued efforts since this time have been dedicated to characterizing the structure and function of SIK1. Such research has laid the ground work for our understanding of SIK1 action and regulation in tissue and stimuli dependent manners. The fundamental findings of this dissertation continue in this tradition and include investigations of SIK1 regulatory mechanisms in skeletal muscle cells, the cellular and physiological effects of SIK1 loss of function in vitro and in vivo, and intracellular metabolic and mitochondrial regulation by this …

Involvement Of The Receptor For Advanced Glycation End Products (Rage) In Progression Of Pancreatic Cancer, Nancy Azizian Ms

Dissertations & Theses (Open Access)

Oncogenic KRAS is central to several cancer types including pancreatic ductal adenocarcinoma (PDAC), but has been determined to be “undruggable”. Recent studies have indicated that oncogenic KRAS is not constitutively active but relies on a feed-forward stimulatory mechanism involving inflammation. In the current study we investigated the mechanisms by which, the receptor for advanced glycation end products (RAGE) affects and maintains KRAS activity. We observed that RAGE levels were elevated and there was a shift in the levels of specific isoforms upon inflammation in pancreatic cells and PDAC. Furthermore, RAGE agonists were found to increase Ras activity and downstream signaling …

Mechanisms Underlying The Sensitivity And Resistance Of Gastric Cancer Cells To Met Inhibitors, Rebecca Schroeder

Dissertations & Theses (Open Access)

MET amplification has been clinically credentialed as a therapeutic target in gastric cancer, but the molecular mechanisms underlying sensitivity and resistance to MET inhibitors are still not well understood. Using whole-genome mRNA expression profiling, we identified autophagy as a top molecular pathway that was activated by the MET inhibitor crizotinib in drug-sensitive human gastric cancer cells, and functional studies confirmed that crizotinib increased autophagy levels in the drug sensitive cells in a concentration-dependent manner. We then used chemical and molecular approaches to inhibit autophagy in order to define its role in cell death. The clinically available inhibitor of autophagy, chloroquine, …

Clinical And Therapeutic Significance Of Obesity In Melanoma, Jennifer L. Mcquade

Dissertations & Theses (Open Access)

While the FDA approval of targeted and immune therapies in metastatic melanoma (MM) have dramatically improved outcomes in this disease, de novo and/or acquired resistance can limit the clinical benefit of these agents. The IGF-1/PI3K/AKT pathway has been implicated in resistance to both targeted and immune therapy. The IGF-1/PI3K/AKT pathway has also been shown to play a key role in the pathogenesis of obesity in other malignancies. To date, the impact of energy balance on clinical outcomes and therapeutic response in MM has not been studied. I hypothesized that energy balance would impact the molecular biology, behavior, and drug sensitivity …

Proteomic Identification Of Histone Post-Translational Modifications Induced By Dna Double-Strand Breaks And Novel Proteins Involved In The Dna Damage Response, Pingping Wang

Dissertations & Theses (Open Access)

Inaccurate repair of DNA double-strand breaks (DSBs) can lead to DNA mutation and chromosome rearrangements, causing human diseases such as cancer. Although we know the basic mechanisms of DSB repair, the added complexities in the chromatin context are unclear. This is partially due to the lack of unbiased systems for identifying proteins and post-translational modifications (PTMs) involved in DSB repair. In this work, we established a novel method, termed DSB-ChAP-MS (Double Strand Break-Chromatin Affinity Purification with Mass Spectrometry), for the affinity purification of a sequence-specific single copy endogenous chromosomal locus containing a DSB, followed by the proteomic identification of enriched …