Triple Negative Breast Cancer (TNBC) is the most difficult type of breast cancer to treat because the chance of recurring is high and survival is typically less than 5 years. Due to lack of the usual molecular targets- estrogen and progesterone receptors and human epidermal growth factor receptor-2- anti-hormonal therapy is eliminated as a possible treatment for TNBC since the tumor does not grow by hormonal stimuli. Standard chemotherapy of TNBC has poor outcomes. Photodynamic therapy (PDT) is an alternative treatment for TNBC. In this study, we examined the properties of several potential photosensitizers for photodynamic therapy in vitro on Triple Negative Breast Cancer cells. The dose response curve for light-dependent cell death of TNBC cells showed an LD50 of &gt;90 micromolar for each of the 4 new photosensitizers we tested. Our next experiment asked where they locate in the cell. The porphyrin derivatives appear to accumulate in membranous organelles. We also examined the mechanism by which the cells die using a TUNEL assay for DNA fragmentation and staining for activated caspase 3. It appears that a significant fraction of the cells dying after treatment with the clinically-tested photosensitizer Foscan and light are dying by apoptosis.

Where, how and how much: Novel porphyrins for photodynamic therapy of triple negative breast cancer

2019 Spring National Meeting

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