MicroRNA-466 inhibits tumor growth and bone metastasis in prostate cancer by direct regulation of osteogenic transcription factor RUNX2

Melissa Colden,Rajvir Dahiya,Varahram Shahryari,Gary Stein,Yuichiro Tanaka,Shahana Majid,Sharanjot Saini,Altaf A Dar,Soichiro Yamamura,Priya V Dahiya

doi:10.1038/cddis.2017.15

Abstract

MicroRNAs (miRNAs) have emerged as key players in cancer progression and metastatic initiation yet their importance in regulating prostate cancer (PCa) metastasis to bone has begun to be appreciated. We employed multimodal strategy based on in-house PCa clinical samples, publicly available TCGA cohorts, a panel of cell lines, in silico analyses, and a series of in vitro and in vivo assays to investigate the role of miR-466 in PCa. Expression analyses revealed that miR-466 is under-expressed in PCa compared to normal tissues. Reconstitution of miR-466 in metastatic PCa cell lines impaired their oncogenic functions such as cell proliferation, migration/invasion and induced cell cycle arrest, and apoptosis compared to control miRNA. Conversely, attenuation of miR-466 in normal prostate cells induced tumorigenic characteristics. miR-466 suppressed PCa growth and metastasis through direct targeting of bone-related transcription factor RUNX2. Overexpression of miR-466 caused a marked downregulation of integrated network of RUNX2 target genes such as osteopontin, osteocalcin, ANGPTs, MMP11 including Fyn, pAkt, FAK and vimentin that are known to be involved in migration, invasion, angiogenesis, EMT and metastasis. Xenograft models indicate that miR-466 inhibits primary orthotopic tumor growth and spontaneous metastasis to bone. Receiver operating curve and Kaplan–Meier analyses show that miR-466 expression can discriminate between malignant and normal prostate tissues; and can predict biochemical relapse. In conclusion, our data strongly suggests miR-466-mediated attenuation of RUNX2 as a novel therapeutic approach to regulate PCa growth, particularly metastasis to bone. This study is the first report documenting the anti-bone metastatic role and clinical significance of miR-466 in prostate cancer.

Highlights

Prostate cancer is the second most leading cause of cancer related deaths among American men.[1]
These findings suggest that RUNX2 can imbue neoplastic cells with the capacity to breakdown the architecture of surrounding tissues, potentially releasing tumor supporting factors indicating that RUNX2 may facilitate a bone-mimetic program that helps cells adapt and thrive in this foreign environment
Experimental evidence has demonstrated that RUNX2, a transcription factor essential for osteogenesis, is a key regulator of bone metastasis that becomes highly activated in prostate cancer cells that metastasize to bone.[34,35]

Summary

Introduction

Prostate cancer is the second most leading cause of cancer related deaths among American men.[1]. MiRNA deregulation is an important component of this landscape given the oncogenic and tumor-suppressive functions of miRNAs.[18] Since malignant cells have dysregulated expression of miRNAs, which in turn control or are controlled by the dysregulation of multiple protein-coding oncogenes or tumor suppressor genes, these miRNAs may be important for the development of miRNAbased therapies.[18] In addition miRNAs have great potential as diagnostic and prognostic biomarkers Owing to their tissue specificity, miRNAs have become useful tools for defining the origin of tumors in poorly differentiated cancers.[19] With the advent of miRNA expression profiles, significant efforts have been made to correlate miRNA expression with tumor prognosis.[20,21,22,23] These reports even suggest that expression profiling of miRNAs may be a more accurate method of classifying cancer subtypes than using the expression profiles of protein-coding genes.[22,24] Various studies have established miRNA expression patterns as potential biomarkers for diagnosis, prognosis, personalized therapy, disease management and clinical outcome in various cancers.[25,26,27,28,29,30] To date, 28 645 miRNAs have been identified (http://www.mirbase.org) their role in disease pathogenesis is not well documented.

Methods

Results

Conclusion