Upregulation of miR-21 and miR-106b in plasma and tissues as a possible prognostic marker in aggressive breast cancer

Abstract

Background: The miRNAs are referred to small non-coding RNAs (consisting of 18 to 25 nucleotides). Functional studies have shown their functions to be oncogenes or tumor suppressor genes in different types of cancers. The miR-106b and miR-21 have been identified to participate in the biological behaviors of cells. This study aimed to evaluate the tissue and plasma levels of miR-21 and miR-106b in patients with breast cancer who were diagnosed with ductal carcinoma. Methods: In total, 40 cases of breast cancer patients 180 samples were examined in this project. Samples included ductal carcinoma breast tumors (n=40), normal breast tissues of the margin of the tumor (n=40) and 20 samples from unaffected mammary tissue of females undergoing reduction mammoplasty (control group), plasma samples of patients with breast cancer (n=40), and plasma of non-affected individuals (n=40). The expression levels of miR-106b and miR-21 were determined using SYBR Green real-time RT-PCR assay in breast tissues and plasma of cancerous patients in comparison to the controls. Results: MiR-106b and miR-21 revealed much higher expression in tissues and plasma of patients with breast cancer in comparison to that in the group of control (P<0.001). High levels of mir-106b and miR-21 expression in plasma and tumor tissues were highly correlated with tumors in higher stages and lymph node involvement (P<0.0001). Conclusions: Based on the obtained results, upregulation of miR-106b and miR-21 in the plasma of patients with breast cancer can act as a possible non-invasive biomarker for breast cancer prognosis. Further follow-up studies are required to confirm this.