Date of Award


Document Type




First Reader

Dr. Tim Hayes

Second Reader

Dr. Ruth Plymale

Third Reader

Dr. Myra Houser


Triple negative breast cancer is an aggressive family of cancers that are extremely difficult to treat. Therefore, the prognosis for most patients with TNBC is poor. The goal of this research is to determine if photodynamic therapy could be a possible option for TNBC in the future using MDA-MB231 cells. MDA-MB231 cells were originally isolated from a patient with triple negative breast cancer and have been used for many studies, so they would work well for this study. Photodynamic therapy uses compounds called photosensitizing agents which are taken up by all tissues in the body and then activated by light. This creates a reactive oxygen species in the cell which is thought to cause cell death. To quantify cell death, an MTT assay was performed. The assay showed concentration-dependent cell death in the plates that were exposed to light. The plates that weren't exposed to light showed some dark toxicity at the highest concentrations. However, the cell death due to dark toxicity is small compared to cell death seen in the cells exposed to light. In addition to measuring cell death, experiments were performed to determine the mechanism of cell death. Antibodies were used to stain the cell for DNA fragmentation, which is a sign of apoptosis. The cells were also co-stained with four antibodies to test for the mechanism of cell death. The results from the antibody-staining assays suggested that the cells were dying mostly by caspase-mediated apoptosis. In addition, staining for oxidative damage and autophagy were also seen.



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