Upregulation of miR-206 is a potential diagnostic biomarker in breast cancer

Abstract

Breast cancer is one of the most common malignancies, and like most cancers, most cases are caused by somatic mutations. Due to estrogen's role in the growth, differentiation, and division of breast and endometrial cancer cells, tamoxifen is used as an estrogen receptor antagonist in breast cancer cells with estrogen receptor (ER +) has a special place, which unfortunately in one-third of the Cases are resisted. This study aimed to investigate the effect of tamoxifen-treated tumor-derived exosomes on the expression pattern of Twist and Bcl-2 oncogenic genes in fibroblast cells. MCF-7 breast cancer cell line and fibroblast cells were purchased and cultured in a complete culture medium. After the appropriate number of cells was reached, they were treated with the appropriate concentration of tamoxifen. Cellular supernatant was then gathered in flasks, and exosomes were extracted from them. After extracting RNA from exosomes and cDNA synthesis, the expression level of miR-206, Twist-1, and Bcl-2 genes were evaluated using the Real-Time PCR method. The electronic microscope results confirmed the correctness of the exosomes isolated from the tumor cell culture medium. It has also been shown that tamoxifen treatment increases the expression of miR-206 in exosomes derived from breast tumor cells. The control group which has been kept untreated induced the expression level of Twist-1 and Bcl-2 genes time-dependently. However, when tamoxifen-treated tumor-derived exosomes treated the target cells, the expression level of oncogenic miRs Twist-1 and Bcl-2 were declined over time. Overall, this study showed that tamoxifen treatment on breast cancer cells could apply its antioncogenic effects on tumor stromal cells, such as fibroblasts, by altering the expression levels of exosomal microRNAs in tumor cells.