miR-518f-5p decreases tetraspanin CD9 protein levels and differentially affects non-tumourigenic prostate and prostate cancer cell migration and adhesion

// Danielle R. Bond 1, 4 , Crystal Naudin 1, 3 , Adam P. Carroll 1, 5 , Belinda J. Goldie 1, 2 , Joshua S. Brzozowski 1 , Helen M. Jankowski 1 , Murray J. Cairns 1, 5 , Leonie K. Ashman 1 , Christopher J. Scarlett 4 and Judith Weidenhofer 1 1 School of Biomedical Science and Pharmacy, The University of Newcastle and Hunter Medical Research Institute (HMRI), NSW, Newcastle, Australia 2 Department of Biochemistry and Molecular Biology, Monash University, Clayton, Australia 3 Department of Pediatrics, Emory University, Atlanta, GA, USA 4 School of Environmental and Life Sciences, The University of Newcastle and Hunter Medical Research Institute (HMRI), NSW, Newcastle, Australia 5 Schizophrenia Research Institute, Sydney, NSW, Australia Correspondence to: Judith Weidenhofer, email: judith.weidenhofer@newcastle.edu.au Keywords: miR-518f-5p; prostate cancer; CD9; transcript regulation; metastasis Received: May 26, 2017      Accepted: November 15, 2017      Published: December 07, 2017 ABSTRACT Tetraspanin CD9 is generally considered to be a metastasis suppressor, with decreased levels associated with progression and metastasis in many advanced stage cancers. Little is known about the cause of CD9 dysregulation in prostate cancer, however there are several miRNA-binding sites in the 3´UTR of the transcript suggesting it could be post-transcriptionally regulated. Using microarrays and luciferase assays in tumourigenic and non-tumourigenic prostate cell lines we identified miR-518f-5p as a regulator of the CD9 3'UTR gene expression, and decreased expression of endogenous CD9 in non-tumorigenic prostate RWPE1 and prostate cancer DU145 cells. This resulted in differential functional effects, in which RWPE1 cells showed increased migration and decreased adhesion to extracellular matrix substrates, whereas DU145 cells showed decreased migration and increased adhesion. Moreover, overexpression of miR-518f-5p significantly increased proliferation between 48h and 72h in normal RWPE1 cells, with no effect on tumourigenic DU145 cell proliferation. These results show that tetraspanin CD9 is regulated by miRNAs in prostate cell lines and that due to differential functional effects in non-tumourigenic versus tumourigenic prostate cells, miR-518f-5p may be an effective biomarker and/or therapeutic target for prostate cancer progression.