Master of Science, The Ohio State University, 2007, Graduate School

Committee: Not Provided (Other) Subjects:

Doctor of Philosophy, The Ohio State University, 1986, Graduate School

Committee: Not Provided (Other) Subjects: Agriculture

Doctor of Philosophy, The Ohio State University, 1981, Graduate School

Committee: Not Provided (Other) Subjects: Health Sciences

Doctor of Philosophy, The Ohio State University, 1976, Graduate School

Committee: Not Provided (Other) Subjects: Health Sciences

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, 2003, Veterinary Biosciences

Parathyroid Hormone-related Protein (PTHrP) is the causative factor of humoral hypercalcemia of malignancy (HHM) observed in patients with adult T-cell leukemia/lymphoma (ATLL). Human T-Lymphotropic Virus Type-1 (HTLV-1) is the etiology of ATLL. We developed a SCID/beige mouse model of HHM to study the pathogenesis of HHM in ATLL. SCID/beige mice inoculated intraperitoneally with human RV-ATL cells developed lymphoma in the mesentery and multiple organs. RV-ATL cells were immunohistochemically positive for PTHrP and expressed high levels of PTHrP mRNA in a HTLV-1 Tax-independent manner. Mice with lymphoma developed severe hypercalcemia, and their plasma PTHrP concentrations correlated positively with calcium concentrations. Bone densitometry and histomorphometry in lymphoma-bearing mice revealed significant bone loss due to marked increase osteoclastic bone resorption. There was a strong inverse relationship between PTHrP and tax/rex mRNA expression using quantitative RT-PCR in RV-ATL and other HTLV-1 cell lines. The PTHrP gene is regulated by three promoter regions (P1, P2, and P3). Quantitative RT-PCR for alternative PTHrP promoter usage in RV-ATL and HTLV-1 cell lines revealed that P3-initiated transcripts were the most abundant in cells with low tax and high PTHrP mRNA expression. We observed constitutive and specific binding of ETS-1 to an ETS binding site (P3 EBS) in the P3 region using nuclear extracts from RV-ATL cells. Transfection experiments in Jurkat T cells resulted in increased transcription of P3-luciferase constructs in response to PMA and ionomycin mediated through P3 EBS. Stimulation with PMA and ionomycin also induced a protein/DNA complex formation on P3 EBS identical to that observed in RV-ATL cells. Co-transfection with Ets-1 and constitutively active Mek-1 expression vectors in Jurkat T cells resulted in a robust induction of luciferase activity under the regulation of P3. The activation was mediated by P3 EBS. Nuclear extracts from Jurkat T c (open full item for complete abstract)

Committee: Thomas Rosol (Advisor) Subjects: