Defense Date
2024
Document Type
Thesis
Degree Name
Master of Science
Department
Biomedical Engineering
First Advisor
Joshua Cohen
Second Advisor
Zvi Schwartz
Third Advisor
Hengbin Wang
Fourth Advisor
Barbara Boyan
Abstract
Laryngeal squamous cell carcinoma (LSCC) has garnered attention as a sex-hormone-dependent cancer with notable responsiveness to 17β-estradiol (E2), in which it’s tumorigenesis can be mediated through estrogen receptors (ER). The ESR1 gene encodes for the classical full-length ERα66, as well as splice variants ERα36 and ERα46. Previous studies have shown that an active vitamin D3metabolite, 24R,25(OH)2D3. has pro-tumorigenic or anti-tumorigenic responses in LSCC cells with different ER profiles, and that the tumor cells have the capability of localized production of vitamin D metabolites at the cellular level when treated with 25(OH)D3-d6 We hypothesized that E2 modulates the local production of 24R,25(OH)2D3 to increase it when 24R,25(OH)2D3 benefits tumorigenesis, or decrease it when 24R,25(OH)2D3 reduces tumorigenesis. We measured the amount of the enzyme CYP24A1, responsible for metabolizing 25(OH)D3 into 24,25(OH)2D3, and the enzyme CYP27B1, responsible for hydroxylating 25(OH)D3 into 1,25(OH)2D3 in UM-SCC-12 (ERα66-positive) and UM-SCC-11A (ERα66-negative) LSCC cell lines by western blot, with or without E2 treatment. Cells were treated with E2 or vehicle for 9 minutes or 24 hours respectively. The cells were then treated with deuterated 25(OH)D3, and the amount of deuterated 1,25(OH)2D3 and 24,25(OH)2D3 secreted by the cells into the cell media was measured via high-performance liquid chromatography-mass spectroscopy (HPLC-MS). E2 differentially regulated the protein levels of the enzymes CYP24A1 and CYP27B1, reducing both CYP24A1 and CYP27B1 levels in UM-SCC-11A cells after 9 minutes of treatment. E2 reduced CYP24A1 levels and increased CYP27B1 levels in UM-SCC-12 cells after 24 hours of treatment. E2 increased the levels of 24,25(OH)2D3 in UM-SCC-12 cells while reducing levels of 24,25(OH)2D3 in UM-SCC-11A cells at 24 hours of E2 treatment. These findings highlight that E2 increases production of 24,25(OH)2D3 in UM-SCC-12 that respond to 24R,25(OH)2D3 treatment in a pro-tumorigenic manner which may result in an increase in the autocrine pro-tumorigenic impact of 24R,25(OH)2D3. In addition, E2 decreases production of 24,25(OH)2D3 in UM-SCC-11A that respond to 24R,25(OH)2D3 treatment in an anti-tumorigenic manner. Furthermore, the findings indicate different ER profiles effect the local production of 24,25(OH)2D3. in the presence of E2 in LSCC.
Rights
© The Author
Is Part Of
VCU University Archives
Is Part Of
VCU Theses and Dissertations
Date of Submission
5-15-2024