Developing tools for paper-based cultures to interrogate oxygen's role in cancer progression Public Deposited

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  • March 22, 2019
Creator
  • Boyce, Matthew
    • Affiliation: College of Arts and Sciences, Department of Chemistry
Abstract
  • Oxygen plays a direct role in controlling cellular phenotype and invasiveness through hypoxia-inducible transcription factors. These factors, which induce signaling pathways under low-oxygen tensions (i.e., hypoxia), are involved with the maintenance of healthy tissue but also contribute to cancer progression. Poor vascularization within rapidly growing tumors leads to the production of atypical gradients of oxygen, which induces heterogeneity within the tumor population and selects for increasingly aggressive phenotypes. To better understand the relationship between extracellular oxygen tension and cancer cell phenotype, in vitro models are needed. Paper-based cultures are an emerging platform capable of generating thick, tissue-like constructs of cells by simply stacking together cell-laden paper scaffolds. Controlling the diffusion of medium into these cultures results in the formation of oxygen, nutrient, and waste gradients through diffusion-consumption mechanisms similar to tumorous tissue. After prolonged incubation, these cultures can be disassembled by peeling the scaffolds apart, and individual scaffolds can be analyzed. The ease of generating gradients and disassembling the cultures into individual layers makes this platform well suited for analyzing cell phenotype relative to placement along an oxygen gradient. In this work, PBCs were used to explore the relationship between oxygen gradients and cancer chemosensitivity. Quantification of oxygen gradients within PBCs was performed using luminescent oxygen-sensors. Development and characterization of these sensors confirmed their high sensitive at low oxygen tensions, photostablility, and compatibility with prolonged cultures. These sensors were used to measure oxygen gradients in PBCs containing different densities of a colon carcinoma cell line, HCT-116. Dosing these cultures with a cytotoxic molecule, SN-38, showed regional differences chemosensivitiy with cells in hypoxic regions exhibiting increased chemoresistance. In addition to studying gradients in PBCs, we also fabricated a fluidic device capable of generating oxygen gradients across static three-dimensional (3D) cultures. Currently, PBCs are unable to generate oxygen gradients without also generating nutrient and waste gradients. With this device, we can decouple oxygen gradients from nutrient and waste gradients, and study changes in cell phenotype in real-time relative to the cell’s location in an oxygen gradient.
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Advisor
  • Glish, Gary
  • Jorgenson, James
  • Hummon, Amanda
  • Walker, Glenn
  • Lockett, Matthew
Degree
  • Doctor of Philosophy
Degree granting institution
  • University of North Carolina at Chapel Hill
Graduation year
  • 2018
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