The effect of oleuropein on apoptotic pathway regulators in breast cancer cells

In spite of advancements in breast cancer therapy, this disease is still one of the significant causes of women fatalities globally. Dysregulation of miRNA plays a pivotal role in the initiation and progression of cancer. Therefore, the administration of herbal compounds with anticancer effects through controlling microRNA expression can be considered as a promising therapy for cancer. Oleuropein is the most prevalent phenolic compound in olive. Given its domestic consumption, low cost, and nontoxicity for human beings, oleuropein can be used in combination with the standard chemotherapy drugs. To this end, we examined the effect of oleuropein on two breast cancer cell lines (MCF7 and MDA-MB-231). Our findings revealed that oleuropein significantly decreased cell viability in a dose- and time-dependent manner, while it increased the apoptosis in MCF7 and MDA-MB-231 cells. In the presence of oleuropein, the expression levels of miR-125b, miR-16, miR-34a, p53, p21, and TNFRS10B increased, while that of bcl-2, mcl1, miR-221, miR-29a and miR-21 decreased. The findings pointed out that oeluropein may induce apoptosis via not only increasing the expression of pro-apoptotic genes and tumor suppressor miRNAs, but also decreasing the expression of anti-apoptotic genes and oncomiR. Consequently, oleuropein can be regarded as a suitable herbal medication for cancer therapy.