High uPAR and Low miR-221 Expression Predict Poor Disease-Free Survival in Triple-Negative Breast Cancer

Background: Triple-negative breast cancer (TNBC) is associated with poor prognosis and limited targeted treatment options. The urokinase plasminogen activator receptor (uPAR) contributes to tumor aggressiveness and may be regulated by microRNAs such as miR-221. This study aimed to evaluate the prognostic relevance of uPAR mRNA and miR-221 expression in TNBC. Methods: uPAR mRNA and miR-221 expression levels were quantified by real-time PCR in tumor tissues from 101 patients with TNBC. Associations with clinicopathological parameters and disease-free survival (DFS) were analyzed using univariate and multivariable Cox regression models. In silico analyses of publicly available datasets were performed for validation and, in addition, for further miR-221 target prediction. Results: In both univariate and multivariable analyses, high uPAR mRNA expression was associated with shorter DFS, whereas, in contrast, elevated miR-221 expression correlated with improved DFS. No inverse correlation between uPAR and miR-221 expression was observed, making a direct regulatory miR-221/uPAR axis in TNBC unlikely. Still, combined analysis revealed a pronounced additive prognostic effect, with high uPAR and low miR-221 expression identifying patients with the poorest DFS. These findings were supported by in silico analysis with publicly available patient data. Finally, other potential miR-221 targets were identified by applying in silico target prediction. Conclusions: uPAR and miR-221 represent independent prognostic markers in TNBC. Their combined expression provides additional prognostic value for disease-free survival and supports their potential relevance as biomarkers and therapeutic targets in TNBC.