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

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.

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.

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).

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.