Emily Kech

Introduction. In the United States, women have a 1 in 8 lifetime risk of developing breast cancer¹. Acquired or inherited mutations in DNA can cause normal breast cells to become cancerous². Factors such as increasing age, female gender, obesity, alcohol consumption, and lack of exercise are known to increase risk^2-3. ω-3 and ω-6 fatty acids are essential polyunsaturated fatty acids (PUFAs) important in maintaining the structure and functionality of the cell membrane⁴. Studies have found that the total amount of ω-3 fatty acids along with the ω-3 to ω-6 ratio consumed are important risk-reducing factors^4-5. A better understanding of the role of ω-3 PUFAs in breast cancer could lead to the potential decrease in breast cancer risk. Methods. HB4a (untransformed) and HB4aC5.2 (HER-2-overexpressing) breast cancer cells were treated with DHA, an ω-3 PUFA, and confocal microscopy was used to visualize lipid rafts⁶. Downstream protein levels were determined through Western blotting, and translocation of pro-apoptotic protein BAD to the mitochondria was visualized with flow cytometry⁶. MDA-MB-231 triple-negative breast cancer cells were treated with various DHA concentrations and cell viability was analyzed by MTT assay while Western blotting was utilized to determine the expression of inflammasome pathway components⁷. The amount of caspase-1 was assessed with flow cytometry, IL-1β secretion by ELISA, and active gasdermin D through Western blotting⁷. Additionally, cells were stained using propidium iodide to test for pore formation⁷. Results. The oncogenic transformation of HB4aC5.2 cells resulted in an increase in lipid raft formation which was disrupted by DHA treatment⁶. Stimulation by DHA was found to inhibit activation of Akt and ERK1/2 downstream proteins and increase BAD expression in the mitochondria, thereby potentiating the induction of apoptosis⁶. DHA treatment decreased MDA-MB-231 cell viability, increased ASC protein levels, and reduced pro-caspase-1 and pro-IL-1β expression, suggesting their cleavage or activation⁷. Furthermore, DHA increased levels of caspase-1, IL-β secretion, and active gasdermin D in association with pyroptosis induction and significantly enhanced membrane pore formation⁷. Conclusions. In HB4aC5.2 cells, DHA treatment was found to disrupt lipid raft formation, block HER-2 signaling, and result in cell apoptosis. The viability of MDA-MB-231 cells was decreased through ω-3 DHA treatment without affecting that of normal cells. DHA was determined to trigger pyroptosis through the presence of pyroptosis markers, membrane pore formation, and subsequent cell death. Studies suggest that DHA, through its induction of cell death, could be used in the future as a therapeutic agent for breast cancer.

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