Breast cancer treatments have developed greatly in the past years. However, even with these treatments, breast cancer continues to be a threat to many. There are instances wherein these treatments do not completely get rid of the cancer cells, which could lead to metastasis or tumor recurrence. Cancer cells that result from these events usually end up resistant to previously used treatments.
The focus of this study was to determine if citral could be used to induce a form of cell death called apoptosis in these drug-resistant breast cancer cells. To replicate breast cancer in vitro, the breast cancer cell line MDA-MB-231 was used.
Cytotoxicity of citral on MDA-MB-231 cells was determined using the MTT assay. In addition to this they also used MDA-MB-231 cells to form spheroids that mimic drug-resistant breast cancer cells. Results of these assays showed that the citral's cytotoxic effect on breast cancer cells is dose-dependent and that citral can kill drug-resistant breast cancer cells.
MDA-MB-231 spheroids were also subjected to Annexin V/ 7 AAD flow cytometry to determine if citral can cause them to undergo apoptosis. The results of this experiment reveals that adding citral will induce early and late apoptosis in the cells. The dosage-dependence of citral's effect can also be observed in this experiment.
Aldefluor assay was also done to determine if aldehyde dehydrogenase positive cells, which have been linked with drug-resistance, can be inhibited. Less number of cells were observed for the secondary spheroids. This means that ability of drug-resistant cells to self-renew was reduced.
Lastly, quantitative real time-PCR and western blot were performed to determine the potential mechanism for citral effect. These experiments look into the genes that are expressed in the citral-treated cancer cells. Based on the results of these experiments, citral was able to reduce the ability of spheroids to self-renew. Aside from this, the down-regulation of Wnt/?-catenin pathway was also observed.
Overall, this study proves that citral can be used to treat drug-resistant breast cancer cells. It does so by inducing apoptosis, as well as, inhibiting growth and self-renewal. This cytotoxic activity of citral is facilitated by the down-regulation of the Wnt/beta-catenin pathway. (Related: Plant phytonutrients shown to alter genes that halt cancer metastasis.)
Aside from its potential as a cancer treatment, citral has many other benefits, such as:
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