Abstract PR09: MicroRNA-1205 regulation of FRYL and aggressive prostate cancer in men of African ancestry
Authors: Naidoo Michelle K. , Levine Fayola , Gillot Tamara , Ali Thahmina , Krampis Konstantinos , Orunmuyi Akintunde , Olapade-Olaopa E.O. , Ogunwobi Olorunseun O. 
Published: August 2020

Men of African ancestry (moAA) have increased likelihood for development of aggressive prostate cancer (PCa). PCa deaths are often associated with castration-resistant prostate cancer (CRPC) due to maintenance of androgen receptor (AR) signaling in PCa cells following androgen ablation therapy (ADT). The 8q24 chromosomal locus is a highly susceptible PCa region that carries risk genetic variants associated with increased incidence of aggressive PCa in moAA. This region also carries frequent amplifications of the PVT1 gene, a nonprotein coding gene that encodes microRNA-1205 whose function was previously unknown. We examined miR-1205 mRNA expression in a cohort of normal (n=22), benign prostatic hyperplasia (n=42), and PCa (n=26) histologically confirmed prostatic tissues obtained from prostatectomy or transrectal biopsies of moAA in Ibadan, Nigeria. A Tukey post hoc test revealed decreased miR-1205 expression in benign prostatic hyperplasia (4.61 ± 7.5) and PCa (3.39 ± 3.53) when compared to normal tissues (6.55 ± 9.5), suggesting that miR-1205 may function as a tumor suppressor and loss of miR-1205 is characteristic of PCa in moAA. In vitro studies revealed decreased miR-1205 expression in CRPC (C4-2B and 22RV1) cells when compared to non-CRPC (LNCaP) cells, suggesting a role for miR-1205 in CRPC. Furthermore, we observed significant inhibition of tumor growth in NOD/SCID gamma mice implanted with C4-2B cells that were administered our novel synthetic analog of miR-1205 (patent pending) when compared to mice treated with a scramble oligonucleotide, indicating that miR-1205 can suppress CRPC tumors. We identified Fry-like (FRYL) as a putative target of miR-1205 using a miSVR computer algorithm and subsequently observed FRYL and AR overexpression in prostate tumors compared to normal tissue from fourteen PCa patients when whole-transcriptome analysis was performed using the Galaxy web platform. Moreover, FRYL was overexpressed in CRPC cells when compared with non-CRPC cells, further suggesting a role in CRPC development. C4-2B cells transfected with miR-1205 and the 3′ UTR of FRYL in a luciferase expressing vector revealed a significant decrease in luciferase activity when compared to control cells, indicating direct binding of miR-1205 to the 3′ UTR of FRYL. These observations strongly suggest that miR-1205 acts as a tumor suppressor by directly targeting FRYL mRNA in PCa cells. FRYL is predicted to regulate dendritic branching, leading to our hypothesis that FRYL plays a role in the development of PCa with neuroendocrine differentiation (PCND), a resulting mechanism due to ADT resistance. We observed that FRYL mRNA was overexpressed and miR-1205 was significantly underexpressed after fourteen days of inducing PCND in LNCaP cells, suggesting that miR-1205 regulation of FRYL mRNA may play a role in PCND development. Further understanding miR-1205 regulation of FRYL may provide novel insights into the molecular mechanisms of aggressive PCa.

This abstract is also being presented as Poster B068.

Citation Format: Michelle K. Naidoo, Fayola Levine, Tamara Gillot, Thahmina Ali, Konstantinos Krampis, Akintunde Orunmuyi, E.O. Olapade-Olaopa, Olorunseun O. Ogunwobi. MicroRNA-1205 regulation of FRYL and aggressive prostate cancer in men of African ancestry [abstract]. In: Proceedings of the Eleventh AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2018 Nov 2-5; New Orleans, LA. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2020;29(6 Suppl):Abstract nr PR09.