MiR-221 Is Specifically Elevated in PC3 Cells and its Deletion Reduces Adhesion, Motility and Growth

Abstract

Background/aim: MiR-221, often described both as an oncogenic microRNA and as a tumour suppressor, targets mRNAs involved in carcinogenesis. While other oncogenic microRNAs showed correlations with prostate cancer cell lines' aggressiveness, miR-221 showed an unusual overexpression in PC3.

Materials and methods: CRISPR was used to delete miR-221 from PC3 cells. Analysing the characteristics of PC3^miR-221del cells, a reduced growth rate and expression of cell-cycle genes was observed. In global gene expression/ontology analysis of PC3^miR-221del cells, cell-cell and cell-substrate adhesion pathways were found to be greatly affected. In addition, reduced levels of adhesion, invasion and motility for PC3^miR-221del cells, a change in F-actin localisation and a reduction of EMT markers were observed.

Results: The tumour suppressor gene, DIRAS3, was a predicted target of miR-221. In PC3^miR-221del cells DIRAS3 was up-regulated at the gene and protein level. Ectopic expression of DIRAS3 in PC3^wt cells recapitulated the cellular morphology changes seen in PC3^miR-221del cells. DIRAS3 3'UTR was more stable in PC3^miR-221del cells, as measured by semi-quantitative PCR and luciferase fusion reporter assays.

Conclusion: MiR-221 promotes aggressiveness of PC3 cells by down-regulating DIRAS3, and promoting epithelial-to-mesenchymal transition.

Keywords: CRISPR; MicroRNA; PC3; prostate.