MicroRNA‐147b induces neuroendocrine differentiation of prostate cancer cells by targeting ribosomal protein RPS15A

Abstract

Background Prostate cancer (PCa) is the leading cause of cancer related deaths in men, often androgen deprivation therapy (ADT) leads to the progression of androgen independent PCa (AIPC) which further leads to Neuroendocrine PCa (NEPC). Identifying the molecular mechanisms which navigate the neuroendocrine differentiation (NED) of PCa cells is clinically relevant. It has been suggested that the micro RNAs (miRNAs) play an important role in the regulation of intrinsic mechanisms relevant to tumor progression, resistance as a result leads to poor prognosis. miR‐147b has been transpiring as one of the deregulated miRNAs associated with the occurrence of multiple cancers. The present study has studied the role of miRNA‐147b in inducing NEPC. Methods To investigate the functional role of miR‐147b in NEPC, we have expressed miRNA mimics or inhibitors in PCa cells and monitored the progression of NEPC along with PCa cell proliferation and survival. The molecular mechanism miRNA‐147b follows was studied using western blot and reverse transcription polymerase chain analysis. miRNA target prediction using bioinformatics tools followed by target validation using luciferase reporter assays was performed. Results In the present study, we found that miR‐147b is highly expressed in AIPC cell lines in particular neuroendocrine cells NCI‐H660 and NE‐LNCaP derived from LNCaP. Mechanistic studies revealed that overexpression of miR‐147b or miRNA mimics induced NED in LNCaP cells in in‐vitro while its inhibitor reversed the NE features (increased NE markers and reduced prostate specific antigen) of PC3, NCI‐H660 and NE‐LNCaP cells. In addition, miR‐147b reduced the proliferation rate of LNCaP cells via elevated p27kip1 and lowered cyclin D1 for promoting differentiation. In reporter assays, we have identified ribosomal protein S15A (RPS15A) is a direct target of miRNA‐147b and RPS15A expression was negatively regulated by miR‐147b in PCa cells. Furthermore, we also report that RPS15A is downregulated in NEPC cells and its expression is inversely correlated with NE markers. Conclusion Targeting the miR‐147b ‐ RPS15A axis may overcome the progression of NEPC and serve as a novel therapeutic target to attenuate NED progression of PCa.

Targeting Key Players of Neuroendocrine Differentiation in Prostate Cancer

“…The RNA-binding protein LIN28B can also be targeted with a series of small molecule inhibitors (Ln7, Ln15 and Ln115) that have shown ability to block CSC characteristics and suppress SOX2 expression [162]. Inhibition of miR-147b, miR-194 and miR-32 leads to the reversal of NE features and suppresses growth of PC cell lines [74,75,78]. As mentioned before, MYCN regulates the miR-421/ATM pathway to promote development of therapeutic resistance in NEPC.…”

“…On the other hand, upregulation of miR-194 and miR-147b is commonly observed in NEPC. miR-194 targets FOXA1 [74] while miR-147b targets the Ribosomal Protein S15a (RPS15A), which is downregulated in NEPC cells and inversely correlates with NE markers [75]. Additional miRNAs involved in NEPC are the miR-708, miR-106b~25 cluster, miR-32 and miR-204.…”

Targeting Key Players of Neuroendocrine Differentiation in Prostate Cancer

“…On the other hand, upregulation of miR-194 and miR-147b is commonly observed in NEPC. miR-194 targets FOXA1 [ 79 ], while miR-147b targets the Ribosomal Protein S15a (RPS15A), which is downregulated in NEPC cells and inversely correlates with NE markers [ 80 ]. Additional miRNAs involved in NEPC are the miR-708, miR-106b~25 cluster, miR-32 and miR-204.…”

“…The RNA-binding protein LIN28B can also be targeted with a series of small molecule inhibitors (Ln7, Ln15 and Ln115) that have shown the ability to block CSC characteristics and suppress SOX2 expression [ 173 ]. Inhibition of miR-147b, miR-194 and miR-32 leads to the reversal of NE features and suppresses the growth of PC cell lines [ 79 , 80 , 83 ]. As mentioned before, MYCN regulates the miR-421/ATM pathway to promote the development of therapeutic resistance in NEPC.…”