Increased fucosylation has a pivotal role in multidrug resistance of breast cancer cells through miR-224-3p targeting FUT4.

Fucosylation is the final step in the glycosylation machinery, which produces glycans involved in tumor multidrug resistance development. MicroRNAs (miRNAs) are endogenous negative regulators of gene expression and have been implicated in most cellular processes of tumors, including drug resistance. This study was undertaken to determine the roles of fucosylation and miR-224-3p in multidrug resistance of human breast cancer cell lines. Comparative analysis revealed differential modification patterns of fucosylation of the fucosylated N-glycans in drug-resistant T47D/ADR cells and sensitive line T47D cells. The expressional profiles of fucosyltransferase genes in two pairs of parental and chemoresistant human breast cancer cell lines showed that FUT4 was up-regulated highly in MDR cell lines. Altered level of FUT4 affected the drug-resistant phenotype of T47D and T47D/ADR cells both in vitro and in vivo. By bioinformatics analysis, we identified FUT4 as one of the miR-224-3p-targeted genes. Further studies showed an inverse relationship between of FUT4 and miR-224-3p in parental and ADR-resistant breast cancer cells, wherein miR-224-3p was downregulated in resistant cells. 3'-UTR dual-luciferase reporter assay confirmed that miR-224-3p directly targeted 3'-untranslation region (3'-UTR) of FUT4 mRNA. In addition, miR-224-3p overexpression sensitized T47D/ADR cells to chemotherapeutics and reduced the growth rate of breast cancer xenografts in vivo. Our results indicate that FUT4 and miR-224-3p are crucial regulators of cancer response to chemotherapy, and may serve as therapeutic targets to reverse chemotherapy resistance in breast cancer.