Targeting Wnt/EZH2/microRNA-708 signaling pathway inhibits neuroendocrine differentiation in prostate cancer

Jingxuan Shan,Moza K Al-Kowari,Issam Al-Bozom,Lotfi Chouchane,Khalid Al-Rumaihi,Pu Li,Sirin W J Abuaqel,Mariam A Al-Muftah

doi:10.1038/s41420-019-0218-y

Abstract

Prostate cancer (PC) castration resistance has been linked to the differentiation of PC luminal cells into hormone-refractory neuroendocrine (NE) cells. However, the molecular mechanisms controlling the emergence of lethal NE prostate cancer (NEPC) remain unclear. The present study aimed to investigate the mechanisms underlying the transition from prostate adenocarcinoma to NEPC. The microRNA miR-708 was involved in NE differentiation and was downregulated in NEPC cells and tumor specimens. miR-708 targeted Sestrin-3 to inhibit Forkhead Box O1 (FOXO1) phosphorylation, resulting in apoptosis of prostate adenocarcinoma cells and AKT-inactivated NEPC cells, the latter of which was consistent with the progression of tumor xenografts in mice under miR-708 treatment. In silico analysis of PC and NEPC tumor specimens suggested that the polycomb repressive complex subunit Enhancer of zeste homolog 2 (EZH2) was particularly overexpressed in NEPC. Notably, EZH2 bound to the miR-708 promoter and induced its silencing in NEPC. Inhibition of EZH2 prevented NE differentiation of PC cells. EZH2 expression was regulated by both Cyclin Dependent Kinase 1 (CDK1) and Wnt signaling. Silencing transcription factor 4 (TCF4), as a key protein in Wnt signaling, prevented NEPC formation. These results provide a molecular basis for the roles of miR-708 and EZH2 in NE differentiation in PC and highlight a new paradigm in NEPC formation and survival.

Highlights

Prostate cancer (PC) is the second most commonly diagnosed and the fifth leading cause of cancer-related death in men[1]
Conditioning with charcoal-stripped serum provides optimal conditions for induction of NE differentiation ex vivo LNCaP cells are androgen-dependent human PC cells derived from supraclavicular lymph node metastasis, C4–2 cells are androgen-independent aggressively metastatic PC cells isolated from bone[14], and DU145 cells are human androgen-independent cells derived from brain metastasis[15]
CS-FBS-treated cells expressed significantly higher levels of chromogranin A (CgA) and neuron-specific enolase (NSE) compared with control cells and cells treated with IL-6, EPI, or FSK (Fig. 1b–d)

Summary

Introduction

Prostate cancer (PC) is the second most commonly diagnosed and the fifth leading cause of cancer-related death in men[1]. Most patients with PC respond to androgen-ablation therapies, which exploit the androgensensitivity of PC cells by either lowering serum androgen levels or blocking androgen receptor (AR) activity, resulting in apoptotic cancer cell death. These treatments include gonadropin-releasing hormone analogs, which. NE differentiation is an oncogenic process leading to NEPC cells, which are epithelial-type prostate cells that share morphological and functional characteristics with neurons. NEPC cells secrete neuronal markers, such as chromogranin A (CgA) and neuron-specific enolase (NSE)[9] They increase the proliferation of neighboring non-NE cancer cells in a paracrine manner, through the provision of hormonal peptide-mediated growth factors and anti-apoptotic properties[10].

Methods

Results

Conclusion