Master of Science, The Ohio State University, 2022, Animal Sciences

The dairy cow requires a fully grown and developed udder to produce copious amounts of milk during lactation. Most mammary growth and development occurs during the animal's first gestation, however coupled at this time is the increased prevalence of intramammary infections (IMI). Such IMI are expected to impair mammary growth and shortchange development, negatively impacting future milk production. Dairy heifers represent a significant financial investment for producers and therefore should enter first lactation healthy so that they yield maximal return on investment. However, how these IMI affect mammary gland growth and development in rapidly growing and developing mammary glands has not been investigated. The objectives of these works were to histologically compare uninfected and Staphylococcus aureus-infected mammary glands by quantifying tissue areas occupied by different tissue types and determine whether infection status affects the degree of cellular proliferation and apoptosis in rapidly growing mammary glands. Non-lactating dairy heifers (n = 16) were administered estradiol and progesterone for 14 d to stimulate mammary growth and development and 2 quarters of each heifer were either infused with Staphylococcus aureus (CHALL) or served as an uninfected control (UNINF) on d 8. Heifers were randomly euthanized on either the last day of hormonal injections (GRO), or 13 d post-injections (DEV) and mammary iii tissues were collected from the center and edge parenchymal regions of each mammary gland. In GRO tissues, CHALL quarters had less epithelial tissue area and greater tissue area occupied by intralobular stroma, coinciding with the greater percentage of apoptotic mammary epithelial cells (MEC) and lower percentage of apoptotic stromal cells compared to UNINF quarters. Additionally, edge parenchyma contained a greater percentage of apoptotic stromal cells compared to center parenchyma. Coinciding with this observ (open full item for complete abstract)

Committee: Benjamin Enger (Advisor); R. Michael Akers (Committee Member); Sheila Jacobi (Committee Member) Subjects: Animal Sciences

PhD, University of Cincinnati, 2018, Medicine: Cancer and Cell Biology

Breast cancer is the most common cancer and the second leading cause of cancer-related deaths in women in the United States. Advances in early detection and treatments have improved the outcome of patients with localized/regional disease; however, more than 40,000 patients with aggressive distant breast cancers succumb to this disease each year. This highlights the lack of effectiveness of current treatments in advanced metastatic disease and the need to gain further insight of the mechanisms leading to aggressive breast cancer to develop effective therapies to prevent breast cancer progression and decrease disease mortality. Research on mammary gland development has significantly contributed to understand breast cancer, with cellular processes, cell-to-cell interactions, and pathways important for proper mammary gland development been found deregulated in breast cancer. The RON receptor tyrosine kinase and its ligand HGFL have been recently implicated in breast cancer. However, knowledge of the role of RON and HGFL in regulating mammary gland development and breast cancer progression is limited. Studies presented in this thesis have provided valuable insights that have aided our understanding of the importance and complexity of the HGFL-RON signaling in normal mammary gland development and breast cancer. Studies discussed here have identified novel HGFL-RON-mediated interactions between mammary epithelial cells/tumor cells and cells within the microenvironment that are crucial for proper mammary gland development and breast cancer progression. In addition, studies examining the role of HGFL-RON signaling in mammary gland development provided valuable information about the different cellular compartments where HGFL-RON signaling occurs and led to the studies examining the cell-type specific functions of HGFL-RON signaling in breast cancer progression. Studies discussed in this thesis revealed that activation of HGFL-RON signaling in tumor epithelial cells, breast ca (open full item for complete abstract)

Committee: Susan Waltz Ph.D. (Committee Chair); Jun-Lin Guan Ph.D. (Committee Member); Simon Hogan Ph.D. (Committee Member); Shao-Chun Wang Ph.D. (Committee Member); Susanne Wells Ph.D. (Committee Member) Subjects: Cellular Biology

PhD, University of Cincinnati, 2014, Medicine: Toxicology (Environmental Health)

The vitamin D3 receptor (VDR) is an established negative regulator of mammary gland development and breast cancer as VDR null mice exhibit enhanced epithelial growth during pubertal breast development and are more susceptible to induced carcinogenesis in the mammary gland. Furthermore, the actions of VDR in the breast are largely dependent on the ligand, vitamin D3. However, it is estimated that over 1 billion people worldwide are vitamin D3 deficient or insufficient, including millions of growing children. Despite the alarming number of people with low systemic vitamin D3 levels, little is known about the repercussions of inadequate VDR signaling during critical times of growth and development, such as mammary gland development, and future disease risk. In this dissertation, we studied the cell-type specific contributions of VDR signaling in the breast during mammary gland development and the protective role of VDR in an aggressive form of breast cancer mediated by oncogenic Ron receptor tyrosine kinase overexpression. We show that VDR signaling in both mammary epithelial cells and adipocytes govern ductal outgrowth through the regulation of epithelial cell proliferation and apoptosis within terminal end buds. Mechanistically, adipocytes secrete growth regulatory cytokines such as IL-6 in response to vitamin D3 for VDR-mediated paracrine regulation of epithelial cell fate. In the context of breast cancer, oncogenic Ron is overexpressed in roughly 50% of all human cases. Ron-mediated mammary tumorigenesis requires activation of downstream ß-catenin signaling, which we demonstrate to be antagonized by vitamin D3 through the VDR. Both mammary gland hyperplasia and tumor onset were significantly delayed with VDR signaling and correlated with decreased levels of ß-catenin target genes involved in growth regulation and invasion. Moreover, vitamin D3-dependent VDR signaling increased expression of dickkopf-related protein 1, an extracellular inhibitor of canonical Wnt/ß-c (open full item for complete abstract)

Committee: Shuk-Mei Ho Ph.D. (Committee Chair); Nira Ben-Jonathan Ph.D. (Committee Member); Mary Beth Genter Ph.D. (Committee Member); Susan Kasper Ph.D. (Committee Member); Susan Waltz Ph.D. (Committee Member); Glendon Michael Zinser Ph.D. (Committee Member) Subjects: Developmental Biology

PhD, University of Cincinnati, 2009, Medicine : Cell and Molecular Biology

The Ron receptor tyrosine kinase is overexpressed in many human cancers including colorectal and breast, and studies have established Ron as a predictor of disease outcome and as a therapeutic target. Ron overexpression and constitutive activation contributes to the tumorigenic properties of human colon cancer cells. Moreover, metastatic dissemination of colon cancer cells from primary orthotopic tumors in mice can be reduced upon Ron knockdown. The majority of hereditary and sporadic colorectal cancers harbor aberrant Apc/β-catenin signaling, however, the relationship between Ron, Apc, and β-catenin signaling in intestinal tumorigenesis is not well understood. We sought to test the requirement of Ron tyrosine kinase signaling for initiation of intestinal tumors in vivo using a well-characterized mouse model of mutant Apc-driven intestinal tumorigenesis. By generating (ApcMin/+ mice with a targeted deletion of the tyrosine kinase domain of Ron (RonTK-/-), we found that Ron is not required for intestinal adenoma formation, and that Ron loss increases tumor burden in a large fraction of mice. Unexpectedly, the loss of Ron in non-transformed intestinal epithelium significantly increases crypt cell proliferation, which may lead to an increased susceptibility to tumor initiation in this model. β-catenin localization and target gene expression were not significantly altered in ApcMin/+;RonTK-/- mouse tumors or normal intestine compared to controls, suggesting that Ron is not required for β-catenin signaling in this model. Like in colon cancer, Ron overexpression has also been observed in approximately half of human breast cancers. Mammary-specific overexpression of Ron in mice results in mammary carcinomas in 100% of mice that metastasize to the lungs and liver, supporting the conclusion that Ron overexpression is a causal oncogenic factor in breast cancer. Interestingly, mammary glands from virgin mice with aberrant Ron expression have dilated mammary ducts and sparse du (open full item for complete abstract)

Committee: Susan Waltz PhD (Committee Chair); Kathleen Goss PhD (Committee Member); Christopher Wylie PhD (Committee Member); Nelson Horseman PhD (Committee Member); Erik Knudsen PhD (Committee Member); Sohaib Khan PhD (Committee Member) Subjects: Cellular Biology

Doctor of Philosophy, Case Western Reserve University, 2011, Pharmacology

Breast cancer is a heterogeneous disease with distinct subtypes that are predictive of patient prognosis. Luminal subtype tumors confer the most favorable prognosis due to ERα-positivity and response to endocrine therapies. In contrast, basal-like subtype tumors confer the worst prognosis due to intrinsic resistance to chemotherapy and the lack of targeted therapies. The forkhead box transcription factor, FOXA1, is found exclusively in luminal tumors, and positively correlates with ERα and survival. Prior to our study, FOXA1 was known to mediate the development of many tissues and be required for ERα transcriptional activity in breast cancer cells. Given these findings, along with the requirement for ERα in mammary morphogenesis, we hypothesized that FOXA1 would be similarly necessary in this process. Using Foxa1 null mice, we found FOXA1 is required for hormone-induced ductal invasion. Mammary glands null for Foxa1 lack epithelial ERα. The regulation of ERα by FOXA1 is similarly observed in breast cancer cells. These results revealed that FOXA1 is not only required for ERα activity, but also for its expression, and provided a mechanism for the ductal phenotype in Foxa1 knockout glands. The positive correlation between FOXA1 and ERα in breast tumors is significant, but not perfect. FOXA1 is also expressed in luminal breast tumors and cell lines in the absence of ERα prompting us to investigate an ERα-independent role for FOXA1 in maintaining the luminal subtype. FOXA1 silencing in ERα-positive and ERα-negative luminal breast cancer cells decreases luminal gene expression, and concomitantly increases basal gene expression. These cells are also more aggressive in vitro, indicating a shift toward the basal phenotype. FOXA1 binds to a subset of basal genes, and thus, is likely orchestrating repression of these genes at the transcriptional level. These data implicate FOXA1 as a mediator of breast cellular plasticity, and suggest that therapeutically reducing FOXA1 in lu (open full item for complete abstract)

Committee: Ruth Keri PhD (Advisor); Monica Montano PhD (Committee Chair); Noa Noy PhD (Committee Member); Richard Hanson PhD (Committee Member); Mark Jackson PhD (Committee Member) Subjects: Biomedical Research; Developmental Biology; Oncology; Pharmacology