Assessment of Non-Coding RNAs (miR-506 and circRNA 000284) and their Target Gene SNAIL-2 in Breast Tumors: Implications for Prognosis and a Possible Circulating Biomarker

Breast cancer is the most common malignancy among women, and early diagnosis and targeted therapy have garnered significant attention. Non-coding RNAs have emerged as potential diagnostic, prognostic, and treatment biomarkers for breast cancer. This study aimed to evaluate the expression of non-coding RNAs, specifically miR-506 and circular RNA 000284, and their target gene SNAIL-2 in breast cancer patients compared to normal controls. The study also focused on clinicopathological characteristics, and plasma was monitored for expression of circ0000284 to identify a possible accessible cancer-related marker.

Using the SYBR-Green Real-time PCR technique, circ0000284, miR-506, and SNAIL2 expression were analyzed in total RNA extracted from 80 breast tumors compared with normal control. Also, the expression of circ0000284 was monitored in the plasma of breast cancer patients. The association of circ0000284, miR-506, and SNAIL2 expression with clinicopathological characteristics were studied.

The results showed overexpression, down-regulation, and up-regulation of circRNA 000284, miR-506, and SNAIL-2, respectively. These expression changes were associated with advanced stages of the disease and lymph nodal involvement, which are signs of a poor prognosis (<0. 0001). Additionally, a positive direct correlation was observed between circRNA000284 expression in tumors and plasma (<0. 0001). Moreover, it was discovered that circ-0000284 sponged miR-506, causing up-regulation of SNAIL-2 as its mRNA target.

The upregulation of SNAIL-2 as an epithelial-mesenchymal-transition (EMT) factor leads to poor prognosis in breast cancer and is epigenetically regulated by miR-506 and circRNA 000284. Therefore, the overexpression of circRNA000284 in plasma could be considered an indicator of lymph nodal involvement and advanced stages of cancer, and nominated as a poor prognostic biomarker for future considerations.