Date of Award
Master of Science (MS)
Brian W. Booth, PhD
Angela Alexander-Bryant, PhD
Jessica Larsen, PhD
Triple negative breast cancer (TNBC) is the most resilient form of breast cancer, being one of the leading causes of death for women and making up 7% of all cancer deaths. Photodynamic therapy (PDT) offers a minimally invasive solution to TNBC as a passive-targeting treatment that reduces the need for other well established yet harsh treatments that can be taxing on the patient. PDT involves the use of a high-energy red light on the area of a tumor injected with photosensitizers (PS) that generate reactive oxygen species (ROS) in the tumor, triggering cell death. The PS tetra(hydroxyphenyl)chlorin (m-THPC) was used in this study due to its high singlet oxygen yield activated by 660-670 nm. Its hydrophobic nature requires the use of the hydrophilic carrier dextran-grafted-polyacrylamide (D-g-PAA) which allows for systemic circulation of m-THPC. D-g-PAA's pH sensitivity encourages the release of m-THPC from D-g-PAA's active amide group when in the presence of low extracellular pH typical of tumors. Gold nanoparticles (GNPs) were also used in this study as they are effective in causing tumor cell death when in the presence of the thermodynamic changes in the area of the tumor during PDT treatment.
The goal of this study was to determine the best concentration of PDT nanocomposite comprised of D-g-PAA encapsulated with GNP loaded with m-THPC for PDT treatment of the TNBC cell line, MDA-MB-231, with minimum damage to the human breast epithelial cell line, MCF10A. PDT nanocomposite concentration 7.2 µg/mL D-g-PAA+GNP loaded with 0.72 µg/mL m-THPC was determined to be the most effective in treating TNBC after statistical analysis of cell counts and MTT assay, determining that this PDT nanocomposite concentration was twice as effective as the other concentration also considered, 6.0 µg/mL D-g-PAA+GNP loaded with 0.6 µg/mL m-THPC. TUNEL assays were used to confirm that apoptosis was the mode of cell death initiated by nanocomposites. Immunohistochemistry (IHC) staining showed activation of cleaved caspase-9, cleaved caspase-3, and BCL2. All three are in pathways for cell death and initiated following the nanocomposite activation with red light. This study supports that PDT with nanocomposite offers an effective treatment for TNBC in vitro.
Warren, Hunter S., "Photodynamic Therapy to Treat Triple Negative Breast Cancer in Vitro" (2023). All Theses. 4088.