Effects of Tunicamycin and N-acetylcysteine on Expression of Autophagy Markers and Cell Viability in MDA-MB-231 Breast Cancer Cells

The worldwide incidence rate for cancer has been rising. However, the molecular mechanisms involved in tumor growth and metastasis are unclear. Autophagy is a cellular pathway that leads to cell death or survival depending on the specific condition of the tumor cells. The aim of this study was to evaluate the effects of activation or inhibition of the autophagy pathway using tunicamycin or N-acetylcysteine on cell viability in the MDA-MB-231 breast cancer cell line.

MDA-MB-231 cells were cultured in the presence of different doses of tunicamycin or N-acetylcysteine. Then, a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide (MTT) assay was performed for the evaluation of tumor cell viability. Real-time PCR was carried out to evaluate the expression of the genes encoding for Becline-1 and the mammalian target of rapamycin (mTOR) (as autophagy markers) in the MDA-MB-231 cell line. The LC3-II to LC3-I ratio and p62 were measured with western blotting.

Tunicamycin significantly increased autophagy markers and inhibited cell viability in a time- and dose-dependent manner. A negative significant correlation was observed between the expression of autophagy markers and cell viability. However, N-acetylcysteine resulted in decreased autophagy and increased cell viability just at a concentration of 2mM.

Tunicamycin leads to activation of the autophagy pathway, resulting in a decrease in cell viability in breast cancer cells (MDA-MB-231); and N-acetylcysteine, at a low concentration, can inhibit autophagy and increase cell viability. Thus, the autophagy pathway can be considered a target in cancer treatment.