Targeting of FK506 binding protein 5 by miR-203 affects the progression of breast cancer via regulating the fatty acid degradation pathway and potential drug-repurposing.

Increasing number of studies have suggested that microRNA (miR)-203 is a potential prognostic marker for breast cancer. However, the specific molecular mechanism underlying the effects of miR-203 remains unknown. The present study aimed to explore the molecular target and underlying mechanisms of action of miR-203 in breast cancer via bioinformatics analysis and cellular assays, such as wound healing assay and western blotting. In the present study, 17 candidate target genes of miR-203 were identified in the downregulated differentially expressed genes from Affymetrix microarray and TargetScan 7.2 database. Subsequently, FK506 binding protein 5 (FKBP5) was considered as the miR-203 target by 3 different hub gene analysis methods (EcCentricity, Betweenness and Stress). FKBP5 protein expression was significantly downregulated in SUM159 cells transfected with miR-203 mimics compared with SUM159 cells transfected with miR-203 negative control (NC) in western blot analysis. High expression of FKBP5 was associated with poor prognosis in breast cancer based on the results obtained from the Kaplan-Meier Plotter database. In addition, the wound healing assay indicated that the inhibition of migration due to miR-203 overexpression in SUM159 cells was reversed by FKBP5 overexpression. These results suggested that miR-203 may directly target FKBP5. In addition, Gene Set Enrichment Analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analysis revealed that miR-203 might play a role in breast cancer via the 'fatty acid degradation' KEGG pathway. Notably, the levels of fatty acids were significantly reduced in SUM159 cells transfected with miR-203 mimics compared with SUM159 cells transfected with miR-203 NC when assessed by the fatty acid content assay. Finally, virtual screening analysis revealed that ZINC000003944422 may be a potential inhibitor of FKBP5. In summary, the present study demonstrated that miR-203 may directly target FKBP5 in breast cancer via fatty acid degradation and potential drugs, hence providing a novel treatment approach for breast cancer.