ABSTRACT
Breast cancer remains the most prevalent malignancy among women
worldwide, and the search for reliable biomarkers to enhance early detection
and monitor therapeutic response remains a clinical necessity. Among
potential candidates, microRNA-21 (miR-21) has gained considerable
attention as an oncogenic regulator involved in tumor proliferation, invasion,
and therapy resistance. This study aimed to evaluate the diagnostic potential
and therapeutic relevance of circulating miR-21 in breast cancer patients.
Blood samples were obtained from 50 breast cancer patients and 25
healthy volunteers, in addition to 10 samples were collected from patients of
paired pre- and post-therapy. Circulating miRNAs were isolated using the
Presto™️ miRNA Purification Kit, reverse transcribed with EasyScript®️ One-
Step SuperMix, and quantified by qRT-PCR.
Circulating miR-21 levels were significantly elevated in breast cancer
patients compared with healthy controls (6.148-fold, p<0.0001),
demonstrating excellent diagnostic performance (ROC-AUC = 1.0). Post-
therapy samples showed an approximately 50% reduction in miR-21
expression (p<0.0004). Significant correlations were observed between
metastasis and TNM stage (p=0.015) and between ER and PR expression
(p<0.001). Circulating miR-21 shows strong potential as a sensitive biomarker
for breast cancer diagnosis and as an indicator of therapeutic response.
