Acifidication Induced Cell Death in MDA-MB-231 Triple Negative Human Breast Cancer Cells Using O-Nitrobenzaldehyde




Holliday, Steve Dale

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This study investigated the use of light activation of the small molecule o-Nitrobenzaldehyde (o-NBA) to produce lethal levels of acidity in MDA-MB-231 triple negative breast cancer cells. o-NBA is a small molecule, that when excited with U.V. light, releases an H+ ion and forms a stable intermediate. Previous work had shown that o-NBA rapidly crosses the cell membrane, and when bath applied and excited with an appropriate light source, can be used to induce acidification in the cells of interest. By varying the concentration of o-NBA and the duration of the light exposure, varying levels of acidification can be produced. Previous unpublished work in our lab showed that a sufficient concentration of o-NBA could be used to induce acidity driven cell death in MCF-7 human breast cancer cells. Due to the greater unmet clinical need for effective treatments for triple negative breast cancers and the known dysregulation of intracellular pH regulation in aggressive cancers, we expanded our work to MDA-MB-231 cells. This study used the fluorescent pH sensitive dye BCECF to confirm that our o-NBA acidification process produced a drop in pH, which was between 0.15 and 0.40 pH units, in MDA-MB-231 cells. We then used the apoptosis marker Annexin V and the necrosis marker 7- AAD to confirm cell death in response to the o-NBA treatment. We found that our acidification method resulted in 60% of treated cells showing markers for cell death in 3 hours (n = 22), which was significantly than cells treated with un-activated o-NBA, 32% of which showed cell death markers in the same time period (n=27). Cells exposed to the activation light and control cells in our marker dye solution over the same time period showed minimal cell death (4 and 8%, n= 77 and n=44, respectively). We showed that o-NBA activation can cause cell death in MDA-MB231 cells. This research indicates that o-NBA driven acidification may be a viable method for inducing cell death in difficult to treat cancers such as triple negative breast cancers.


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Integrative Biology