Life Sciences Commons^™

Estrogen Receptor (Er) Alpha Regulatory Mechanisms And Therapeutic Strategies In Er+ Breast Cancer, Bianca A. Romo

Dartmouth College Ph.D Dissertations

Breast cancer is among the most frequently diagnosed cancers in the U.S. and is one of the leading causes of cancer-related mortalities, second to lung cancer. Estrogen receptor alpha-positive (ER+) breast cancer accounts for 2/3 of diagnosed cases. Patients diagnosed with this subtype of breast cancer typically undergo endocrine therapy that aims to mitigate the growth-promoting effects of estrogen/ER. While therapies are effective, 1/3 of patients will experience recurrence. To begin addressing this drug-resistant patient population, we investigated potential drug targets involved in response to treatment.

Coregulators have been implicated in the regulation of ER transcriptional activity and subsequently affecting …

Regulation Of The Wnt/Wingless Receptor Lrp6/Arrow By The Deubiquitylating Complex Usp46, Zachary T. Spencer

Dartmouth College Ph.D Dissertations

The evolutionarily conserved Wnt/Wingless signal transduction pathway is critical for the proper development of all animals and implicated in numerous diseases in adulthood. Upon binding of the Wnt/Wingless ligand, a cascade of events culminates in inactivation of the destruction complex, a negative regulator of the pathway, and the subsequent formation of singalosomes which mediate pathway activation. A critical component of signalosome formation is the Wnt/Wingless receptor LRP6/Arrow. Upon canonical pathway activation, LRP6/Arrow undergoes activation via phosphorylation by several kinases and complexes with another Wnt/Wingless receptor Frizzled, along with several cytoplasmic components. While many studies have investigated the regulatory mechanisms of …

Understanding The Implications Of Lineage Plasticity In Breast Cancer Evolution And Chemotherapy Response, Gadisti Aisha Mohamed

Dartmouth College Ph.D Dissertations

Intra-tumoral heterogeneity and the presence of a phenotypically diverse cell population within a single tumor represents a major hurdle in the understanding of tumor progression and dynamics, and complicates the effective diagnosis and management of this disease. One of the ways by which tumors gain intra-tumoral variation is through the acquisition of phenotypic or lineage plasticity, whereby tumor cells evolve away from the lineage of origin and gain altered profiles. These alterations may impart specific survival benefits to different subpopulations of cells, enabling them to proliferate faster, migrate away from the site of the primary tumor or evade drug-induced elimination, …

Cell-Typing And Interaction Analysis Of The Immune Compartment Of The Tumor Microenvironment Using High-Resolution Omics Modalities, Courtney Taylor Schiebout

Dartmouth College Ph.D Dissertations

Single-cell RNA-sequencing (scRNA-seq) has provided a new frontier for the investigation of complex tissues. One ideal candidate for the utilization of this method is the tumor microenvironment (TME). The TME is often host to a complex set of cell populations and behaviors that can be highly influential for cancer inhibition or progression. This is especially true of the immune compartment of the TME: the presence of certain types of immune cells in the TME and their expression profiles can significantly affect cancer prognosis in some cases. By providing individual cell-level gene expression data, scRNA-seq can be highly informative for characterizing …

Characterization Of Cell Type-Specific Molecular Heterogeneity In Cancer Using Multi-Omic Approaches, Min Kyung Lee

Dartmouth College Ph.D Dissertations

Tumors are composed of heterogeneous cell types each with its own unique molecular profiles. Recent advances in single cell genomics technologies have begun to increase our understanding of the molecular heterogeneity that exists in tumors with particular focus on gene expression and chromatin accessibility profiles. However, due to limitations in methods for certain sample types and high cost for single cell genomics, bulk tumor molecular profiling has been and remains widely used. In addition, other facets of single cell epigenomic profiling, particularly methylation and hydroxymethylation, remains underexplored. Thus, investigations to understand the cell type specific epigenetic heterogeneity and the cooperation …

The Roles Of Epithelial–Mesenchymal Plasticity In Tumor Heterogeneity, Metastasis, And Patient Survival In Breast Cancer, Meredith Septer Brown

Dartmouth College Ph.D Dissertations

The Epithelial-to-Mesenchymal transition, a critical cellular process in development, is frequently co-opted by solid tumors to promote invasion and metastasis. In particular, the hybrid or intermediate EMT state, possessing both epithelial and mesenchymal characteristics, is associated with increased cancer stemness and plasticity. Similarly, intra-tumoral heterogeneity in solid tumors, in particular breast cancer, is associated with poor prognosis, tumor growth, proliferation, drug resistance, and metastasis. We sought to understand the link between the generation of intra-tumoral heterogeneity and the intermediate EMT state and their impact on tumor progression and patient prognosis. As part of my thesis work, I developed a model …