Abstract 3783: Role of microRNA 28-3p in prostate cancer progression

Abstract

Abstract Prostate cancer (PCa) is a leading cause of cancer incidence and mortality among men. Prostate cancer is driven by androgens acting via androgen receptor (AR). Therefore, this cancer is treated with androgen deprivation therapy (ADT) initially. However, the cancer rapidly evolves to be resistant to ADT and progresses to a more invasive stage referred to as ‘Castration Resistant prostate cancer’ (CRPC). CRPC is treated with second generation of AR pathway inhibitors such as Enzalutamide and Abiraterone. These treatments are effective initially. However, drug resistance develops in a significant fraction of patients and the cancer undergoes ‘neuroendocrine trans-differentiation (NED) to a lethal variant called ‘neuroendocrine prostate cancer’ (NEPC). As a result of NED, PCa cells express neuronal markers such as synaptophysin, chromogranin A and enolase. The molecular basis of NED is not yet fully defined. With a focus on identifying the role of microRNAs (miRNAs) in NEPC, we performed small RNA sequencing in CRPC tumors with and without NED. This sequencing identified miR-28-3p to be significantly downregulated in CRPC-NE samples as compared to CRPC-adenocarcinomas (CRPC-Adeno). In view of this, we examined the role of this miRNA in NEPC. Analyses of TCGA data of prostate adenocarcinomas suggest that miR 28-3p has an oncogenic role in primary prostate tumors. However, its expression declines in tumors with increasing Gleason score. We profiled the expression of miR-28-3p in patient-derived xenograft models and clinical CRPC-NE and CRPC-Adeno tissues by real time PCR. Our profiling showed a trend towards downregulation with increased NED. Basal expression of miR 28-3p in various prostate cancer cell lines showed an elevated level in androgen dependent cell lines whereas significantly less expression in NEPC cell lines, LASCPC-01 and NCI-H660. In this study, we generated PC3 cell line that stably expresses miR-28 for understanding its functional role in regulating PCa. Preliminary functional assays including cell viability assay, cell cycle studies and invasion and migration assay suggest a tumor suppressor role of miR-28-3p in advanced prostate cancer. In conclusion, our data shows that miR 28-3p potentially has a biphasic role in PCa, where it is oncogenic in early stages and acts as a tumor suppressor in late stage PCa. Citation Format: Amritha Sreekumar, Sharanjot Saini. Role of microRNA 28-3p in prostate cancer progression. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3783.