Abstract 1409: Reprogramming the alternative polyadenylation of an oncogenic transcription factor as a therapeutic strategy for prostate cancer

Abstract Alternative polyadenylation (APA) of mRNAs is emerging as a powerful new player in cancer biology, driving aggressive cancer behavior by reshaping how oncogenes are regulated. In particular, altered APA typically fuels cancer growth by shortening the 3'UTR of oncogenes, thus altering mRNA stability and reducing the ability of miRNAs to suppress cancer-promoting genes. This marks APA as a new hallmark of cancer malignancy and a promising novel therapeutic target. We focused on prostate cancer (PCa), the tumor with the highest incidence in male population worldwide, and on NFYA oncogene, a driver of aggressive PCa. NFYA encodes for the regulatory subunit of the transcription factor NF-Y, a key player in cell cycle regulation and a well-established actor in cancer. We determined that NFYA undergoes 3’UTR shortening in PCa cells, thus resulting in increased protein level by means of enhanced mRNA stability, reduced nuclear retention, and attenuation of miRNA-mediated repression. Thus, it was of interest to investigate the effect of APA on the remodeling of the quantity and activity of NF-YA oncoprotein in PCa cells, and how this influences PCa behavior and aggressiveness. To explore this process, we aimed to reprogram NFYA APA towards 3’UTR lengthening in PCa cells and evaluated the effects on PCa cell features. Through CRISPR/Cas9 editing and non-degrading antisense oligonucleotides (ASO), we abrogated the usage of the polyadenylation signal (PAS) of the most abundant NFYA 3'UTR isoform, which led to a shift towards increased utilization of the longest NFYA 3’UTR and decreased NF-YA protein. This, in turn, curbed PCa cell proliferation. Similarly, ASO-treated cells forced to use only the most distal PAS displayed reduced protein level and impaired cell growth. Therefore, these findings highlight APA as a crucial post-transcriptional mechanism regulating NF-YA activity in PCa. Moreover, they provide the proof-of-concept for a possible APA-directed and gene-specific therapy. This is further strengthened by the emerging application of ASOs in the clinics, which opens the possibility of their use to therapeutically manipulate the effects of APA in PCa. Overall, our results build the biological rationale for the development of novel and innovative therapeutic opportunities for aggressive PCa based on NFYA APA modulation, possibly combined with standard therapies, which could help treatment optimization and improve patients’ survival in the medium-long term. Citation Format: Giulia Pagani, Chiara Casirati, Stefania Fornezza, Roberta Cacioppo, Paolo Gandellini. Reprogramming the alternative polyadenylation of an oncogenic transcription factor as a therapeutic strategy for prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 1409.