Up‐regulation of miR‐539 impedes PCa cell proliferation, migration and invasion through the inhibition of the TGF‐β signalling pathway. A, proliferation of DU145 cells transfected with SB‐431542, miR‐539 inhibitor, DMSO, miR‐539 inhibitor + DMSO and miR‐539 inhibitor + SB‐431542 measured by MTT assay; B, migration of DU145 cells transfected with SB‐431542, miR‐539 inhibitor, DMSO, miR‐539 inhibitor + DMSO and miR‐539 inhibitor + SB‐431542 measured by scratch test, C, invasion of DU145 cells transfected with SB‐431542, miR‐539 inhibitor, DMSO and miR‐539 inhibitor + SB‐431542 measured by transwell assay; D, Western blot analysis of vimentin, E‐cadherin, c‐Myc, Smad4, Snail1 and SLUG proteins in DU145 cell lines transfected with SB‐431542, miR‐539 inhibitor, DMSO, miR‐539 inhibitor + DMSO and miR‐539 inhibitor + SB‐431542; *P < 0.05, compared with the DMSO group; # P < 0.05, compared with the miR‐539 inhibitor + DMSO group