The evaluation of melatonin and EGF interaction on breast cancer metastasis.

Objectives: Metastasis in breast cancer is the first cause of death in patients. The epidermal growth factor (EGF) increases cancer cells' invasion, and migration. Melatonin's inhibitory effects on various types of cancer were confirmed. This study aimed to investigate whether melatonin could apply its impact through the EGF-related pathways or not.

Methods: First, MDA-MB-231 and MCF7 cells were cultured, and then melatonin effects on cell viability were determined by MTT assay. Transwell invasion assay was applied to identify the invasiveness of these breast cancer cell lines under treatment of EGF and melatonin. Real-time RT-PCR then investigated the expression of MMP9 and MMP2 in determined groups. Cell proliferation was also assayed under EGF and melatonin treatment using Ki67 assessment by flow cytometry.

Results: The rate of invasion and migration of EGF-treated cells increased in both groups, in which melatonin caused increased invasion by EGF just in MCF7 cells. MMP9 and MMP2 expression increased significantly in both cell lines under EGF treatment, and melatonin increased these genes' expression in both cell lines (p<0.05). EGF increased the MMP9 and MMP2 gene expression, and melatonin increased EGF-induced expression (p<0.05). The EGF reduced the expression of the Ki67 protein in the MCF7 cell line, which was negatively affected by melatonin and EGF. In contrast, along with melatonin, EGF did not affect the proliferation of the MDA-MB-231 cell line.

Conclusions: The results of this study show that melatonin in the presence of EGF does not show the anti-cancer properties previously described for this substance.