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

Danielle R Bond,Christopher J Scarlett,Crystal Naudin,Helen M Jankowski,Belinda J Goldie,Adam P Carroll,Joshua S Brzozowski,Leonie K Ashman,Murray J Cairns,Judith Weidenhofer

doi:10.18632/oncotarget.23118

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.

Highlights

Prostate cancer affects 1 in 7 men worldwide [1], with around 5% of all new cases diagnosed with advanced stage metastatic prostate cancer for which the 5-year survival rate is only 30% [2], reflecting the lack of curative therapies for this group
The level of CD9 mRNA and protein was determined in a panel of non-tumorigenic (PrEC, RWPE1 and BPH-1) and tumorigenic (LNCaP, PC3, DU145 and WPE1-NB26) prostate cell lines
The aggressive prostate cancer cells had the lowest levels of CD9 cell surface protein (Figure 1D) and total CD9 protein levels compared to non-tumorigenic RWPE1 cells (Figure 1B and 1C)

Summary

Introduction

Prostate cancer affects 1 in 7 men worldwide [1], with around 5% of all new cases diagnosed with advanced stage metastatic prostate cancer for which the 5-year survival rate is only 30% [2], reflecting the lack of curative therapies for this group. Several members of the tetraspanin family of proteins have been implicated in cancer, metastatic cancers [3] and are potential novel drug target candidates to inhibit prostate cancer progression. CD9 knockout mice crossed onto the TRAMP prostate cancer mouse model led to a significant decrease in spontaneous metastasis to the liver [6], thereby implicating CD9 in prostate cancer progression and metastasis. The discrepancy between these two studies warrants further investigation of CD9 in prostate cancer to clarify if CD9 acts as a metastasis suppressor

Objectives

Methods

Results

Conclusion