Abstract 1274: Investigating PLOD2 as a therapeutic target to overcome metastasis in radiorecurrent prostate cancer

Abstract Prostate cancer (PCa) is the second most common cancer in males, with 1 in 8 men developing the disease in their lifetime. For PCa, a common treatment strategy is external beam radiation therapy to the prostate. However, when cancer recurs (radiorecurrent PCa), it often behaves aggressively by invading into surrounding organs or spreading distantly. Radiorecurrent PCa metastasis is therefore a significant cause of morbidity and mortality that must be overcome to improve survival of advanced PCa patients. Proteomic analysis revealed the procollagen enzyme Lysyl Hydroxylase 2 (PLOD2) to be upregulated in our radiorecurrent, and highly aggressive, conventionally fractionated DU145 (DU145-CF) PCa cell line. Given its established function as a mediator of invasion in various other cancers, we sought to characterize the role of PLOD2 in the aggressive phenotype of our radiorecurrent PCa cells. Bioinformatic analysis of clinical data revealed PLOD2 genomic amplification to be significantly associated with biochemical recurrence in PCa patients. Upon further examination in vitro, it was revealed that PLOD2 knockdown significantly reduces matrigel invasion and migration in our radiorecurrent DU145-CF cell line, in addition to numerous other PCa cell lines, including primary cells we derived directly from PCa patients. Using the in vivo chick Chorioallantoic Membrane (CAM) model, we confirmed that PLOD2 knockdown significantly reduces the ability of DU145-CF cells to extravasate from the CAM vasculature into the surrounding stroma, a critical step of the metastatic cascade. To explore mechanisms of metastatic cellular reprogramming downstream of PLOD2, RNA sequencing of DU145-CF cells was conducted; a total of 681 genes were discovered to be dysregulated by PLOD2 knockdown, with their functional analysis suggesting changes in cellular metabolism and respiration. Finally, since PLOD2 is known to be regulated by hypoxia-induced protein HIF1α, we explored whether PLOD2 expression could be inhibited by the HIF1α inhibitor, PX-478. Treatment with PX-478 reduced both HIF1α and PLOD2 protein expression, and significantly reduced invasion, migration, and in vivo extravasation in DU145-CF cells, thereby indicating its potential as a pharmacological inhibitor of HIF1α-associated PLOD2 in radiorecurrent PCa. Together, our results demonstrate for the first time the role of PLOD2 in radiorecurrent PCa invasiveness, and point towards its potential as a therapeutic target to reduce metastasis and improve survival outcomes in PCa patients. Citation Format: Gavin Frame, Hon Leong, Roni Haas, Xiaoyong Huang, Jessica Wright, Paul C. Boutros, Thomas Kislinger, Stanley K. Liu. Investigating PLOD2 as a therapeutic target to overcome metastasis in radiorecurrent prostate cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1274.