Abstract 2363: MicroRNA-1205 modulates FRYL/Aurora A kinase protein-protein interaction in prostate cancer cells

High mortality rates of prostate cancer (PCa) are associated with metastatic castration-resistant prostate cancer (mCRPC) due to the maintenance of androgen receptor (AR) signaling despite androgen deprivation therapies (ADTs). Resistance to second generation ADTs leads to the progression to AR-independent treatment related-neuroendocrine PCa (t-NEPC), which is observed in nearly 1 in 5 men with mCRPC and is associated with very poor outcomes. PCa neuroendocrine differentiation (PCND) occurs in t-NEPC that is characterized by amplification of Aurora A kinase (AurA). However, the mechanisms that drive t-NEPC are poorly understood. Further understanding PCND in ADT resistance may prevent poorer outcomes. The 8q24 chromosomal locus is an important PCa susceptibility region containing genetic variants associated with increased PCa incidence and aggressiveness. PVT1 is a gene located within this region that encodes microRNA-1205 (miR-1205), whose function is largely unknown. We previously reported miR-1205 underexpression in a cohort of histologically confirmed PCa tissue when compared to normal tissue and that exogenous miR-1205 significantly inhibited tumor growth in CRPC in vivo, suggesting that miR-1205 is a tumor suppressor. To understand the molecular mechanism of miR-1205, we first identfied Fry-like (FRYL) as a direct molecular target of miR-1205. FRYL is predicted to regulate dendritic branching which led us to hypothesize that it is involved in PCND. A Weill Cornell Medicine cohort of 29 benign prostate, 66 localized PCa, 73 CRPC, and 36 NEPC samples whose transcriptome was profiled by RNA-seq, we observed significant overexpression of FRYL in NEPC when compared to localized PCa and benign prostate. After validating FRYL as a target, we examined miR-1205 regulation of FRYL in PCND by culturing LNCaP androgen sensitive PCa cells under androgen deprivation conditions. We observed FRYL mRNA overexpression and significant underexpression of miR-1205 in LNCaP-PCND cells when compared to undifferentiated LNCaP cells. To further characterize this mechanism, miR-1205 was inhibited in RWPE-1 non-tumorigenic and LNCaP cells. As a result, FRYL and AurA protein expression was increased along with NEPC marker expression (Neuron specific enolase 2) when compared to cells transfected with a negative control, suggesting that miR-1205 targets FRYL and AurA to promote PCND. However, RNA pulldown analysis showed that AurA is not a direct target of miR-1205. We observed that FRYL and AurA interaction occurs in LNCaP but not in RWPE-1 cells via co-immunoprecipitation. Interestingly, transfection with miR-1205 mimic inhibits FRYL expression, but not AurA in LNCaP. However, miR-1205 mimic inhibits AurA binding to FRYL. Altogether, these data show that miR-1205 modulates FRYL:AurA protein interaction suggesting that miR-1205 regulation of FRYL:AurA interactions may be important in PCND and t-NEPC. Citation Format: Michelle K. Naidoo, Fayola Levine, Princesca Dorsaint, Andrea Sboner, Olorunseun Ogunwobi. MicroRNA-1205 modulates FRYL/Aurora A kinase protein-protein interaction in prostate cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2363.