Loss of exosomal miR-146a-5p from cancer-associated fibroblasts after androgen deprivation therapy contributes to prostate cancer metastasis

Yu Zhang,Mao Ding,Jing Zhao,Yifeng Jing,Sheng Zhao,Yiming Su,Chenyi Jiang,Xiaohai Wang,Yuan Ruan,Bangmin Han,Di Cui,Gaozhen Jia,Shujie Xia

doi:10.1186/s13046-020-01761-1

Abstract

BackgroundAndrogen deprivation therapy (ADT) is the backbone of therapy for advanced prostate cancer (PCa). Despite the good initial response, castration resistance and metastatic progression will inevitably occur. Cancer-associated fibroblasts (CAFs) may be implicated in promoting metastasis of PCa after ADT. Our aim is to investigate the role and mechanism of CAFs-derived exosomes involving in metastasis of PCa after ADT.MethodsPCa cells were co-cultured with exosomes derived from 10 nM dihydrotestosterone (DHT)-treated (simulating the high androgen level of prostate cancer microenvironment) or ethanol (ETOH) -treated (simulating the castration level of prostate cancer microenvironment after ADT) CAFs, and their migration and invasion differences under castration condition were examined both in vitro and in vivo. The miRNA profiles of exosomes derived from DHT-treated CAFs and matched ETOH-treated CAFs were analysed via next generation sequencing. The transfer of exosomal miR-146a-5p from CAFs to PCa cells was identified by fluorescent microscopy. The function and direct target gene of exosomal miR-146a-5p in PCa cells were confirmed through Transwell assays, luciferase reporter, and western blot.ResultsCompared with DHT-treated CAFs, exosomes derived from ETOH-treated CAFs dramatically increased migration and invasion of PCa cells under castration condition. MiR-146a-5p level in exosomes from ETOH-treated CAFs was significantly reduced. The loss of miR-146a-5p may strengthen the epithelial-mesenchymal transition (EMT) to accelerate cancer cells metastasis by modulating epidermal growth factor receptor (EGFR)/ERK pathway.ConclusionsCAFs-derived exosomal miR-146a-5p confers metastasis in PCa cells under ADT through the EGFR/ERK pathway and it may present a new treatment for PCa.

Highlights

Androgen deprivation therapy (ADT) is the backbone of therapy for advanced prostate cancer (PCa)
We performed immunofluorescence to detect the expression of Cancerassociated fibroblasts (CAFs) markers such as α-SMA, FAP, and Vimentin (Fig. 1a and Additional file 2: Figure S2a). we used western blotting assay to detect the androgen receptor (AR) expression in CAFs and found that Androgen receptor (AR) was expressed in all CAFs but at a lower level than LNCaP cells (Additional file 2: Figure S2b)
Previous study showed that inhibiting AR signalling in CAFs might promote PCa cell migration by enhanced secretion of CCL2 and CXCL8 [11], we would like to determine whether exosomes derived from CAF exposed to androgen deprivation might promote migration or invasion of PCa cells

Summary

Introduction

Androgen deprivation therapy (ADT) is the backbone of therapy for advanced prostate cancer (PCa). Androgen deprivation therapy (ADT), including surgical or chemical castration, is the backbone of treatment for all stages of recurrent prostate cancer [2]. Recent researches revealed that in the microenvironment of prostate cancer, cancer-associated fibroblasts (CAFs) are among the most crucial components and are reported to promote tumorigenesis and progression [4,5,6]. Several studies demonstrated that CAFs could promote androgen independence and metastatic progression in prostate cancer [7,8,9]. Bianca et al revealed that inhibiting AR signalling in CAFs could promote prostate cancer cell migration by secreting CCL2 and CXCL8 [11]. Damien et al described that AR signalling in CAFs inhibits prostate cancer cell invasion via maintaining the extracellular matrix (ECM) [12]. The roles of AR in CAFs are still controversial and have been a hot topic in prostate cancer research

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