Effects of sapienic acid on MAPK pathway in melanoma cells

Melanoma, an aggressive form of skin cancer, is an important cause of morbidity and mortality, and its incidence is increasing worldwide. Clarifying the signaling pathways in cancer cells is very helpful in understanding the positive and negative aspects of the treatments to be applied. It has been accepted that membrane lipids have important contributions in the signal transduction process. The amount of fatty acids in the membrane can affect the fluidity as well as change the activation of membrane proteins involved in intracellular pathways. MAPK signal transduction pathways regulate different cellular functions such as proliferation, differentiation, apoptosis, cell-cell adhesion, inflammation, metastasis and invasion in response to various environmental signals and are the main pathways targeted in cancer research. Studies have shown that the amount of sapienic acid (SA), which is naturally produced in the sebum of the skin, in the membrane vesicles of cancer cells is increased compared to normal cells. Although it is naturally found in skin sebum, there is no study in the literature on the effect of SA on the pathways involved in skin cancer. For this reason, we aimed to investigate the effect of SA on the MAPK pathway by exogenous administration to a melanoma cell line. A375 cell lines with malignant melanoma character were used to examine the effects of SA on the MAPK pathway. The cytotoxic effect of SA on A375 cell lines was determined by MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrasodium bromide] assay. Cells were incubated at different time intervals with varying concentrations of SA, the concentration that killed 50% of the cells (IC50 value) was determined by cytotoxicity test, and the cells were photographed with an inverted microscope to see their effects on the cell. In A375 cell lines with MM, short incubations of 0 min, 30 min, 1, 2 and 3 hours, as well as 24 and 48 hours incubations, total protein measurement was made by Bradford method. The proliferative effects of SA were investigated as a result of the epidermal growth factor receptor (EGFR) effect on the cell membrane and a series of effects on the MAPK pathway. Specific protein bands in the MAPK pathway with EGFR were obtained by Western Blot analysis. The TBARS kit was used to measure the level of malondialdehyde (MDA), which is a by-product of lipid peroxidation of SA and reflects the magnitude of oxidative stress. Superoxide Dismutase (SOD) enzyme activities were calculated using the SOD kit. In our study, it was observed that SA had cytotoxic effects on A375 cells as a result of long-term incubations. As a result of short and long-term incubations, it was determined that SA stimulated the MAPK pathway in A375 cells. It proves that bioactive lipids have two opposing effects on the MAPK pathway in cancer prognosis. It is important for the evaluation of chemotherapeutic treatments because sapienic acid has different effects in determined doses and time intervals. Keywords: Sapienic Acid; Malignant Melanoma; MAPK Pathway; Oxidative Stress; Lipid Peroxidation