Bachelor of Science (BS), Ohio University, 2024, Biological Sciences

Parathyroid hormone-related protein (PTHrP) is a hormone originally discovered in cancer patients as a cause of cancer-associated hypercalcemia. PTHrP was then unexpectedly found to be in many normal tissues of the body. PTHrP is similar in function and structure to the well-known hormone, parathyroid hormone (PTH). Previous studies showed that removing the nuclear localization sequence (NLS) and the C-terminus domains of PTHrP in mice (PTHrP 1- 66) caused severe abnormalities including lack of skeletal formation and decreased hematopoiesis (Toribio et al., 2010). These mice usually die within 5 days. Due to the dwarfism of these mice, this thesis explores the relationship of how reduced PTHrP affects the growth hormone (GH) and insulin-like growth factor 1 (IGF-1) axis in the liver of mice. Using quantitative polymerase chain reaction (qPCR) and RNA-sequencing, we found that IGF-1 was decreased in the liver and serum. We also found that GH in serum and its mRNA was normal to increased. The RNA-seq data also showed that the growth hormone receptor (GHR) was slightly downregulated, but genes downstream from the GHR were variably modified. Unexpectedly, the RNA-seq data showed that the most downregulated pathway was the cell cycle pathway.

Committee: Thomas J. Rosol (Advisor) Subjects: Biology

Master of Science, The Ohio State University, 2017, Comparative and Veterinary Medicine

Chronic kidney disease (CKD) is associated with hyperphosphatemia, reduced vitamin D metabolite concentrations, and hyperparathyroidism. This syndrome is known as CKD-mineral and bone disorder (CKD-MBD). Recently it has been shown that increased fibroblast growth factor-23 (FGF23) concentration is one of the earliest biomarkers of CKD in people and cats. It is an independent risk factor for both progression of kidney disease and survival time in humans and cats. FGF23 information in healthy and CKD dogs is lacking. The primary objective of this study was to measure FGF23 concentration in dogs with different stages of CKD and to determine its association with factors involved in CKD-MBD, including phosphate and parathyroid hormone (PTH) concentrations. A secondary aim was to validate an ELISA for measurement of canine plasma FGF23. Thirty-two client-owned dogs with naturally occurring CKD and 10 healthy control dogs were enrolled in this prospective cross-sectional study. A human FGF23 ELISA was used to measure plasma FGF23 and its association with creatinine, phosphate, calcium, and PTH was determined. Plasma FGF23 concentration increased with severity of kidney disease and was significantly different between IRIS stages 1 and 2 versus stages 3 and 4 (P <0.0001). Increased plasma FGF23 concentration occurred more frequently than hyperparathyroidism or hyperphosphatemia in this cohort. Serum creatinine and phosphate concentrations were the strongest independent predictors of FGF23 concentration. Plasma FGF23 concentration increased in CKD dogs as disease progressed. Plasma FGF23 concentration appears to be useful for further study of the pathophysiology of canine CKD-MBD.

Committee: Valerie Parker (Advisor); Ramiro Toribio (Committee Member); Catherine Langston (Committee Member); Dennis Chew (Committee Member) Subjects: Veterinary Services

Master of Science, The Ohio State University, 2016, Comparative and Veterinary Medicine

Primary hyperparathyroidism (PHPTH) results in excessive secretion of parathyroid hormone (PTH) causing hypercalcemia. Vitamin D also contributes to calcium regulation. People with PHPTH and vitamin D deficiency have more severe disease as seen with higher preoperative calcium and longer duration of postoperative hypocalcemia. In people and dogs, a decrease of more than 50% of intraoperative PTH concentration 10 minutes after parathyroidectomy is associated with complete surgical resection of the autonomously functioning gland. Post-operative hypocalcemia after parathyroidectomy necessitates immediate medical intervention and prolonged hospitalization. Distinct pre-operative predictors of postoperative hypocalcemia have not been identified in veterinary medicine. The objective of this study was to prospectively monitor the trends in PTH concentrations and vitamin D metabolites and determine predictive factors for the development of postoperative hypocalcemia. Our hypothesis was that dogs with a greater than 75% percent change between baseline and intraoperative PTH concentrations will be more likely to develop hypocalcemia in the immediate post-operative period. A second hypothesis is that dogs with low vitamin D status will be more likely to develop postoperative hypocalcemia. Dogs that developed postoperative hypocalcemia had a significantly larger decrease in PTH concentration than dogs that remained normocalcemic (p<0.008). All dogs had low preoperative calcidiol concentration. This is the first prospective study examining vitamin D and preoperative factors in dogs with PHPTH as predictors of postoperative hypocalcemia.

Committee: Kathleen Ham DVM, MS, DACVS (Advisor); Dennis Chew DVM, MS, DACVIM (Committee Member); Chen Gilor DVM, PhD, DACVIM (Committee Member) Subjects: Animal Sciences; Animals; Endocrinology; Medicine; Veterinary Services

Doctor of Philosophy, The Ohio State University, 2009, Veterinary Biosciences

Humoral hypercalcemia of malignancy (HHM) is a debilitating syndrome seen in patients with neoplasia of squamous epithelial cell origin. The highest prevalence of HHM is associated with squamous-cell carcinoma of the lung (SCCs) and ranges from 27-66%. HHM results from increased synthesis and secretion of parathyroid hormone-related hormone (PTHrP). The mechanisms that activate PTHrP gene expression in tumors associated with HHM have yet to be identified. The contribution of the epidermal growth factor receptor (EGFR) to HHM in the human lung SCC cell lines, RWGT2 and HARA was investigated. To test the relationship between EGFR activity and PTHrP gene expression, PTHrP mRNA levels were measured by Q-RT-PCR following treatment of lung SCC lines with the EGFR tyrosine kinase inhibitor (TKI) PD153035, anti-amphiregulin antibodies as well as with EGF-ligands. Overall, PTHrP expression was significantly increased with EGF-ligand treatment. The in vivo relationship between EGFR and PTHrP gene expression was investigated using xenograft HARA and RWGT2 HHM models. Hypercalcemic mice were treated with the TKI, gefitinib. RWGT2 plasma calcium levels were significantly reduced at all time points when compared to pretreatment and control values. In conclusion, autocrine activation of PTHrP gene expression is mediated through the EGFR in the RWGT2 line, however, our results indicated that the major mechanism of HHM induction in the HARA model was not through EGFR but rather the high concentrations of PTHrP secreted by the HARA line were significantly influenced by exogenous factors. The role of a known regulator of calcium homeostasis in humans, the calcium-sensing receptor (CaR) was investigated. Our experiments evaluate evidence for the expression of the CaR in human lung SCC. We examined if PTHrP secretion and HHM occurs in response to CaR stimulation in the RWGT2, HARA and BEN Australia SCCs. We find that CaR is expressed in lung SCCs and stimulation with extracellular calci (open full item for complete abstract)

Committee: Thomas J. Rosol PhD (Advisor); John Foley PhD (Committee Member); Michael Lairmore PhD (Committee Member); Michael Oglesbee PhD (Committee Member) Subjects: Oncology

Doctor of Philosophy, The Ohio State University, 2005, Veterinary Biosciences

Squamous cell carcinoma (SCC) is a malignant tumor of keratinocytes. Head and neck SCC (H/N SCC) is a common diagnosis in the cat. SCCs often secrete parathyroid hormone related-protein (PTHrP) which induces osteoclastic resorption and contributes to bone destruction. Bone resorption results in the release of transforming growth factor-Β (TGF-Β), which regulates PTHrP via Smad signaling proteins.We developed a PTHrP-secreting feline oropharyngeal SCC cell line (SCCF1). Treatment of cells with TGF-Β increased PTHrP production. A segment of feline PTHrP had a high degree of homology to human and canine PTHrP cDNA and predicted amino acid sequence. PTHrP mRNA was alternatively spliced to the 1-139 and 1-141 isoforms. A mouse xenograft model of feline oral SCC was developed using luciferase-expressing SCCF1 cells. This allowed serial in vivo monitoring of tumor growth using bioluminescent imaging. Using a human pulmonary SCC line (HARA) in an intratibial metastasis model, we investigated the role of tumor-produced PTHrP in the growth of HARA in bone. We disrupted normal osteoclast function by treatment with zoledronic acid or osteoprotegerin. Tumor burden in bone was decreased with either treatment. Osteoclast numbers along tumor-associated bone were not decreased. High local levels of PTHrP may have partially antagonized the anti-osteoclast effects of either drug. Chemical induction of skin tumors in mice heterozygous for Smad2 and Smad3 was used to investigate the role of disruption of the TGF-Β signaling pathway on the development of SCC. Smad3± mice developed fewer tumors than wild-type mice, suggesting an oncogene role. Smad2± mice formed less-differentiated tumors than wild-type mice, supporting a tumor-suppressor role. There was a significant difference in tumor type between the two groups, suggesting that Smad2 and Smad3 regulate different targets. In conclusion, we propose the use of the cat as a natural model for human H/N SCC. In vitro and in vivo studies usi (open full item for complete abstract)

Committee: Thomas Rosol (Advisor) Subjects:

Doctor of Philosophy, Case Western Reserve University, 1990, Biology

Parathyroid hormone has been shown to bind to the β subunit of the proton transporting ATPase found in mitochondria and bacteria. This binding has been examined further with purified F1 ATPase enzyme, submitochondrial particles, and intact mitochondria. PTH specifically causes a three fold activation of ATPase activity of isolated rat kidney mitochondria. Oxidized forms and fragments of PTH were less effective at activating this activity than 1-34 or 1-84 PTH. PTH caused a 12% activation of submitochondrial particle ATPase only when the natural ATPase inhibitor was present and only at pH 6.7. No activation of purified F1 ATPase was observed. Specific binding of the iodinated PTH analog (Nle8,18Tyr34) -bPTH (1-34) could be observed with submitochondrial particles and purified F1 ATPase (K ds of 100 nM and 1 μM, respectively). However, the affinity was lower than with the plasma membrane PTH receptor from bovine kidney. Oxidation of methionine 18 reduced the affinity 60% in the membranes, particles, and pure enzyme; oxidation of methionine 8 reduced the affinity 95%, and oxidation of both methionines decreased binding to undetectable levels. The 3-34 and 7-34 PTH fragments were found to bind the ATPase with higher affinity than expected (K ds of 0.16 and 0.5 4 μM, respectively). The stoichiometry of PTH binding is one molecule per enzyme molecule. PTH reduced the chemical crosslinking of the ATP analog, FSBA, to the α subunit of this enzyme, but did not alter labeling of the enzyme with BzATP, suggesting a PTH interaction with a nucleotide binding site. Direct chemical crosslinking of PTH to the ATPase with the photoactivatable crosslinker SASD was used to study PTH binding. Sequencing of CNBr fragments of PTH-crosslinked β subunit has shown that the sites of PTH interaction with the β subunit are in regions of the molecule that have been implicated as being near noncatalytic ATP binding sites. These studies suggest that PTH binds at a unique site on the β subunit whi (open full item for complete abstract)

Committee: James Zull (Advisor) Subjects: Biology, General