Cancer Biology Commons^™

Pi3kδ Inhibition Alters Cd8 T Cell Differentiation And Reprograms The Tumor Microenvironment Following Adoptive Immunotherapy, Alexandrea Joy Turnquist

Dartmouth College Ph.D Dissertations

T cell exhaustion remains a significant barrier to effective adoptive cell therapy in solid tumors. Here, we demonstrate that in vitro treatment with the PI3Kδ inhibitor CAL-101 generates T cells with enhanced stemness and metabolic fitness, though the stemness of these cells is not dependent on HIF-1α -dependent mechanisms. These cells show increased mitochondrial dependence and spare respiratory capacity while maintaining normal basal metabolism. Under chronic antigen stimulation, CAL-101-treated T cells, including human T cells, resist terminal exhaustion and maintain stem-like properties. Using single-cell RNA sequencing and spatial transcriptomics of B16 melanoma tumors, we found that CAL-101-treated T cells preferentially …

Immune Suppression And Epigenetic Reprogramming In Epithelial-Mesenchymal Transition, Hanxu Lu

Dartmouth College Ph.D Dissertations

Epithelial-mesenchymal transition (EMT) is increasingly recognized as a dynamic spectrum of cellular programthat contributes to tumor progression, metastasis, and therapeutic resistance. Rather than existing as discrete epithelial or mesenchymal phenotypes, tumor cells undergo intermediate EMT states in which epithelial and mesenchymal features are partially and variably expressed. In this thesis, I studied EMT state heterogeneity through two complementary and integrated dimensions: tumor-immune interactions and the dynamic remodeling of epigenetic programs across the EMT spectrum. Using a clonal EMT model derived from the murine triple-negative 4T1 mammary carcinoma cell line, including epithelial, intermediate, and mesenchymal states that are stably maintained in …

Novel Combination Therapies For Estrogen Receptor-Positive Breast Cancer Driven By Rational Molecular Mechanisms, Anneka Lila Johnson

Dartmouth College Ph.D Dissertations

Breast cancer (BC) is the most common non-keratinocyte cancer diagnosed in women in the United States with approximately 300,000 new cases diagnosed each year. Despite a myriad of treatment options, BC remains the second-most deadly cancer. Estrogen receptor-positive (ER+) BC comprises 60-70% of BC diagnoses and is treated with endocrine therapies that limit ER signaling. Despite endocrine therapy options, ~1/3 of patients experience recurrence within 10-20 years of diagnosis. Novel therapeutic strategies are required to limit BC recurrence-related morbidity and mortality.

Radiotherapy is used as an adjuvant treatment for ER+ BC patients prior to the use of endocrine therapy. Radiation …

Identification And Therapeutic Targeting Of Metabolic Alterations In Estrogen Receptor-Positive Breast Cancer, Steven Tau

Dartmouth College Ph.D Dissertations

Estrogen receptor-positive breast cancer remains one of the most frequently diagnosed cancers in women. Despite adjuvant endocrine therapy reducing the rate of recurrence, there remains a significant proportion of patients whose breast cancer will recur years to decades after the initial diagnosis. The underlying biology of tumor cells in the period between initiation of adjuvant therapy and recurrence is relatively unexplored, preventing the development of better treatment options. From a genome-wide screening approach, we identified and characterized broad metabolic reprogramming associated with the persistent cell state. We demonstrate that a decreased ability to metabolize glucose in turn pushes a higher …

Near-Infrared Paired-Agent Imaging For In Vivo Quantification Of Receptor Occupancy In Tumor, Yichen Feng

Dartmouth College Ph.D Dissertations

Accurate assessment of drug receptor occupancy (RO) holds significant importance in both drug development and personalized medicine, as it facilitates quantitative characterization of dose-response relationship for a given drug. This information not only aids appropriate dose selection for clinical trials but also guides personalized dose optimization in precision medicine.

Molecular imaging, utilizing receptor-specific imaging agents for tissue visualization, has emerged as the major option for in vivo measurement of tissue RO. Nonetheless, the abnormal yet complex structure and hemodynamics of tumors often lead to substantial non-specific uptake and retention of imaging agents, thus introducing significant bias to RO measurements. To …

Exploring 3d Genome Interaction And Epigenetic Regulation Via Swi/Snf Complex And Deep Learning Models, Ruoyun Wang

Dartmouth College Ph.D Dissertations

The three-dimensional organization of the genome is fundamental in regulating gene expression and maintaining cellular function. This organization's complexities, influenced by epigenetic marks and chromatin remodeling complexes, are crucial for understanding genomic regulation. Among these, the SWI/SNF complexes are key, facilitating chromatin accessibility and regulating gene activity across cell types. The first part of my dissertation focuses on SWI/SNF complexes, exploring their role in chromatin remodeling and their impact on 3D genome architecture. Utilizing next-generation sequencing (NGS) techniques, this section investigates the interplay between these complexes and chromatin structure. During my research on the SWI/SNF complex, I was intrigued by …

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 …

Chromatin Regulation By Swi/Snf Remodelers In Somatic Stem Cell Maintenance And Transformation, Luke Thomas Deary

Dartmouth College Ph.D Dissertations

Cell identity is defined by the epigenome, whereby chromatin regulators work in concert to promote gene expression programs that serve a cell’s specialized purpose. Mutations in chromatin regulators are amongst the most frequent drivers of human disease, underscoring the importance of understanding their activities in maintaining cell identity and tissue function. In particular, mutations in subunits of the evolutionarily conserved SWI/SNF chromatin remodeling complexes drive diseases across human tissues in both development and adult tissue maintenance5. Three major SWI/SNF complexes exist: BAF, PBAF, and GBAF, which differ in their composition and genomic targeting but share an ATP-dependent catalytic activity to …

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 …