Abstract 4301: ENO1 as a potential target for anti-cancer therapy: Insights into its role in neuroendocrine prostate cancer cell growth and survival

Prostate cancer (PCa) is the second most commonly diagnosed cancer and the leading cause of cancer-related death among men in the United States. Taxane-based chemotherapy with docetaxel (DTX) and cabazitaxel is used as last-line treatment for metastatic castration-resistant prostate cancer (mCRPC). However, these drugs often fail due to the development of chemoresistance. The prostate-specific membrane antigen (PSMA) has emerged as a critical target for theranostics (imaging + therapy) in mCRPC. Nonetheless, around 30% of patients show a limited response, particularly those with low or absent PSMA expression. Given the limitations of targeting PSMA in certain patients, exploring alternative molecular targets such as Enolase (isoforms ENO1 and ENO2) could enhance therapeutic options for patients with mCRPC. ENO1, an enzyme involved in glycolysis, demonstrates potential as an alternative target for mCRPC treatment as it is found on the surface of various tumors. We hypothesized that ENO1 is abundant on the surface of neuroendocrine-like prostate cancer (NEPC-L) cell lines, and that targeting this protein will disrupt key metabolic pathways, resulting in significant anti-cancer effects and reduced tumor growth. Western blot analysis revealed that DTX-sensitive PCa cell lines expressing NEPC markers also express both ENO1 and ENO2. In contrast, DTX-resistant NEPC-L cells expressed ENO1, with limited ENO2 expression, indicating a potential metabolic vulnerability in these cells due to ENO2 downregulation. Additionally, we observed that the cell surface localization of ENO1 in DTX-resistant NEPC-L cell lines varied according to glucose levels. High glucose levels, common in metabolically active metastatic tumors, promoted the cell surface localization of ENO1. By contrast, cells cultured in normal glucose conditions demonstrated lower levels of ENO1 cell surface abundance, likely due to inhibition of the c-MYC oncogene and upregulation of MBP1, a small variant of ENO1 that suppresses c-MYC mediated transcriptional induction of ENO1. We also determined if genetic silencing of ENO1 affects the proliferation and clonogenic ability of NEPC-L cells. Preliminary results following MTT and Clonogenic Assays indicated that ENO1 knockdown with specific siRNAs significantly reduced cell proliferation and clonogenic ability and altered cellular morphology, while preserving cell viability, compared to scramble negative control siRNA. This indicated that while genetic targeting of ENO1 may not necessarily impact tumor cell survival, it could have a dramatic inhibitory effect on tumor growth. Future experiments will explore if ENO1 knockdown re-sensitizes NEPC-L cells to DTX treatment, inhibits tumor-sphere formation, and modifies the stemness properties of these cells, supporting its potential as a novel therapeutic target in patients with drug-resistant NEPC. Citation Format: Krystal Rubi Santiago Torres, Alfonso Duran, Kristen Whitley, Shriya Roy, Frankis Almaguel, Carlos A. Casiano. ENO1 as a potential target for anti-cancer therapy: Insights into its role in neuroendocrine prostate cancer cell growth and survival [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 4301.